DDT 8494 225677556 2008-07-14T21:21:51Z NawlinWiki 301395 icon {{pp-move-vandalism|small=yes}} {{otheruses}} {{Chembox new | Name = '''DDT''' | ImageFile = DDT.svg | ImageSize = 200px | ImageFile1 = DDT-3D-balls.png | ImageFile2 = DDT-3D-vdW.png | ImageName = Chemical structure of DDT | IUPACName = 4,4'-(2,2,2-trichloroethane-<br/>1,1-diyl)bis(chlorobenzene) | Section1 = {{Chembox Identifiers | CASNo = 50-29-3 | SMILES = Clc1ccc(cc1)C(c2ccc(Cl)cc2)C(Cl)(Cl)Cl }} | Section2 = {{Chembox Properties | Formula = C<sub>14</sub>H<sub>9</sub>Cl<sub>5</sub> | MolarMass = 354.49 g/mol | Density = 1.55 g/cm³ <ref name="GESTIS">{{GESTIS|ZVG=12510|CAS=50-29-3|Name=DDT|date=21 October 2007}}</ref> | MeltingPt = 108.5–109 °C <ref name="GESTIS"/> | BoilingPt = 185–187 °C (at 7 Pa) <ref name="GESTIS"/> }} | Section7 = {{Chembox Hazards | EUClass = Yes | EUIndex = | MainHazards = T, N | RPhrases = {{R25}} {{R40}} {{R48/25}} {{R50/53}} | SPhrases = {{(S1/2)}} {{S22}} {{S36/37}} {{S45}} {{S60}} {{S61}} | LD50 = 113 mg/kg (rat) }} }} '''DDT''' (from its trivial name, '''D'''ichloro-'''D'''iphenyl-'''T'''richloroethane) is one of the best known synthetic [[pesticide]]s. It is a chemical with a long, unique, and controversial history. First synthesized in 1874, DDT's insecticidal properties were not discovered until 1939. In the early years of [[World War II]], DDT was used with great effect to control [[mosquito]]es spreading [[malaria]], [[typhus]], and other [[insect]]-borne diseases among both military and civilian populations. The Swiss chemist [[Paul Hermann Müller]] of [[Geigy Pharmaceutical]] was awarded the [[Nobel Prize in Physiology or Medicine]] in 1948 "for his discovery of the high efficiency of DDT as a contact poison against several [[arthropod]]s."<ref name=nobel>[http://nobelprize.org/nobel_prizes/medicine/laureates/1948/ NobelPrize.org: The Nobel Prize in Physiology of Medicine 1948] Accessed July 26, 2007.</ref> After the war, DDT was made available for use as an agricultural [[insecticide]], and soon its production and use skyrocketed.<ref name=EHC9>[http://www.inchem.org/documents/ehc/ehc/ehc009.htm ''Environmental Health Criteria 9: DDT and its derivatives''], World Health Organization, 1979.</ref> In 1962, ''[[Silent Spring]]'' by American biologist [[Rachel Carson]] was published. The book catalogued the environmental impacts of the indiscriminate spraying of DDT in the US and questioned the logic of releasing large amounts of chemicals into the environment without fully understanding their effects on ecology or human health. The book suggested that DDT and other pesticides may cause [[cancer]] and that their agricultural use was a threat to wildlife, particularly birds.<ref name="Silent Spring">{{cite book|title=Silent Spring| first=Rachel| last=Carson| year=1962| publisher=Houghton Mifflin| location=Boston}}</ref> Its publication was one of the signature events in the birth of the [[Environmentalism|environmental movement]]. ''Silent Spring'' resulted in a large public outcry that eventually led to most uses of DDT being banned in the US in 1972.<ref>J. Paull, [http://orgprints.org/10961/ Rachel Carson, A Voice for Organics - the First Hundred Years], Journal of Bio-Dynamics Tasmania, (86) 37-41, 2007.</ref> DDT was subsequently banned for agricultural use worldwide under the [[Stockholm Convention]], but its limited use in [[vector (biology)|disease vector]] [[vector control|control]] continues to this day in certain parts of the world and remains controversial.<ref name="Larson">{{cite journal|last=Larson|first=Kim|date=December 1, 2007|title=Bad Blood|journal=On Earth|issue=Winter 2008|url=http://www.onearth.org/article/bad-blood?|accessdate=June 5, 2008}}</ref> Along with the passage of the [[Endangered Species Act]], the US ban on DDT is cited by scientists as a major factor in the comeback of the [[bald eagle]] in the contiguous US.<ref name="pmid17588911"> E. Stokstad, "Species conservation. Can the bald eagle still soar after it is delisted?", Science 316, 5832 (2007), p. 1689f. [[Digital object identifier|doi]]: [http://www.sciencemag.org/cgi/content/summary/316/5832/1689][http://www.ncbi.nlm.nih.gov/pubmed/17588911]</ref> ==Properties and chemistry== DDT is an [[organochlorine]] insecticide, similar in structure to the pesticides [[dicofol]] and [[methoxychlor]]. It is a highly [[hydrophobic]], colorless, [[crystal]]line solid with a weak, chemical [[odor]]. It is nearly [[soluble|insoluble]] in [[Water (molecule)|water]] but has a good solubility in most [[Organic chemistry|organic]] [[solvent]]s, [[fat]]s, and [[oil (liquid)|oil]]s. DDT does not occur naturally, but is produced by the reaction of [[trichloroethanal|chloral]] (CCl<sub>3</sub>CHO) with [[chlorobenzene]] (C<sub>6</sub>H<sub>5</sub>Cl) in the presence of [[sulfuric acid]], which acts as a [[catalyst]]. Trade names that DDT has been marketed under include include Anofex, Cesarex, Chlorophenothane, Dedelo, Dicophane, Dinocide, Didimac, Digmar, ENT 1506, Genitox, Guesapon, Guesarol, Gexarex, Gyron, Hildit, Ixodex, Kopsol, Kybosh, Neocid, OMS 16, Pentachlorin, Pennsalt, Puritan, Rukseam, R50, and Zerdane. ===Isomers and Related Compounds=== [[Image:OpDDT.png|thumb|''o,p''-DDT, a minor component in commercial DDT.]] Commercial DDT is actually a mixture of several closely related compounds. The major component (77%) is the ''[[Para-|p]]'',''p'' [[isomer]] which is pictured at the top of this article. The ''o'',''p'' isomer (pictured to the right) is also present in significant amounts (15%). [[Dichlorodiphenyldichloroethylene]] (DDE) and [[dichlorodiphenyldichloroethane]] (DDD) make up the balance. DDE and DDD are also the major metabolites and breakdown products of DDT in the environment.<ref name=EHC9/> The term "'''total DDT'''" is often used to refer to the sum of all DDT related compounds (''p,p-''DDT, ''o,p-''DDT, DDE, and DDD) in a sample. ===Production and use statistics=== From 1950 to 1980, when DDT was extensively used in agriculture, more than 40,000 [[tonnes]] were used each year worldwide,<ref name=Geisz>{{cite journal |author=Geisz HN, Dickhut RM, Cochran MA, Fraser WR, Ducklow HW |title=Melting Glaciers: A Probable Source of DDT to the Antarctic Marine Ecosystem |journal=Environ. Sci. Technol. |volume=ASAP |issue= |pages= 3958|year=2005 |month= |doi=10.1021/es702919n |url=http://pubs.acs.org/cgi-bin/abstract.cgi/esthag/asap/abs/es702919n.html |accessdate=2008-05-07}}</ref> and it has been estimated that a total of 1.8 million tonnes of DDT have been produced globally since the 1940s.<ref name="ATSDRc5">[http://www.atsdr.cdc.gov/toxprofiles/tp35-c5.pdf ''Toxicological Profile: for DDT, DDE, and DDE. Chapter Five: Production, Import, Use, and Disposal.''] Agency for Toxic Substances and Disease Registry, September 2002.</ref> In the U.S., where it was manufactured by [[Ciba]],<ref>{{cite news|url=http://www.al.com/news/mobileregister/index.ssf?/base/news/1215162908145190.xml&coll=3|title=McIntosh residents file suit against Ciba|last=DAVID|first=DAVID|date=July 4, 2008|accessdate=2008-07-07}}</ref> [[Montrose Chemical Corporation of California|Montrose Chemical Company]] and [[Velsicol Chemical Corporation]],<ref>{{cite news |url=http://www.themorningsun.com/stories/012708/loc_tests.shtml| title=Tests shed light on how pCBSA got into St. Louis water|last=ROSEMARY|first=ROSEMARY|date=2008-01-27|publisher=Morning Sun|accessdate=2008-05-16}}</ref> production peaked in 1963 at 82,000 tonnes per year.<ref name=EHC9/> More than 600,000 tonnes (1.35 billion lbs) were applied in the U.S. before the 1972 ban, with usage peaking in 1959 with about 36,000 tonnes applied that year.<ref name=EPA1975>[http://www.epa.gov/history/topics/ddt/02.htm DDT Regulatory History: A Brief Survey (to 1975)], U.S. EPA, July 1975.</ref> Currently about 1,000 tonnes of DDT are used annually worldwide in vector control operations.<ref name=Geisz/> India and China are the only countries still producing and exporting the chemical.<ref>{{cite book|title=Farm Chemicals Handbook 2001|publisher=Meister Publishing Company|location=Willoughby Ohio, USA|volume=87|isbn=9991774130}} cited in {{cite news| url=http://www.panna.org/docsPops/docsPops_020501.pdf|title=DDT & Malaria|publisher=International POPs Elimination Network|accessdate=2008-05-16}}</ref> ===Mechanism of action=== DDT is moderately toxic, with a rat [[LD50|LD<sub>50</sub>]] of 113 mg/kg,<ref name = "zvgfrt">World Health Organization, [http://www.who.int/ipcs/publications/pesticides_hazard_rev_3.pdf ''The WHO Recommended Classification of Pesticides by Hazard''], 2005.</ref> and has potent insecticidal properties; it kills by opening [[sodium ion channel]]s in insect [[neuron]]s, causing the neuron to fire spontaneously. This leads to spasms and eventual death. Insects with certain mutations in their sodium channel gene may be resistant to DDT and other similar insecticides. DDT resistance is also conferred by up-regulation of genes expressing [[P450|cytochrome P450]] in some insect species.<ref>{{cite journal |author=Denholm I, Devine GJ, Williamson MS |title=Evolutionary genetics. Insecticide resistance on the move |journal=Science |volume=297 |issue=5590 |pages=2222–3 |year=2002 |pmid=12351778 |doi=10.1126/science.1077266}}</ref> ==History== [[Image:DDT.jpg|thumb|right|250px|Commercial product containing 5% DDT]] First synthesized in 1874 by [[Othmar Zeidler]],<ref>{{cite journal | title = Verbindungen von Chloral mit Brom- und Chlorbenzol | author = Othmar Zeidler | journal = Berichte der deutschen chemischen Gesellschaft | year = 1874 | volume = 7 | issue = 2 | pages = 1180–1181 | doi = 10.1002/cber.18740070278 }}</ref> DDT's insecticidal properties were not discovered until 1939 by the [[Swiss (people)|Swiss]] scientist [[Paul Hermann Müller]], who was awarded the 1948 [[Nobel Prize]] in Physiology and Medicine for his efforts.<ref name=nobel/> ===Use in the 1940s and 1950s=== DDT is the best-known of a number of chlorine-containing [[pesticide]]s used in the 1940s and 1950s. It was used extensively during [[World War II]] by Allied troops in Europe and the Pacific as well as certain civilian populations to control the insect [[Vector (biology)|vector]]s for [[typhus]] and malaria (nearly eliminating typhus as a result). Entire cities in Italy were dusted to control the typhus carried by [[lice]]. DDT also sharply reduced the incidence of [[biting midge]]s in Great Britain, and was used extensively as an agricultural insecticide after 1945. DDT played a small role in the final elimination of malaria in Europe and North America, as malaria had already been eliminated from much of the developed world before the advent of DDT through the use of a range of public health measures and generally increasing health and living standards.<ref>[http://www.onearth.org/article/bad-blood? Bad Blood], Kim Larsen, ''OnEarth'', Winter 2008.</ref> One CDC physician involved in the United States' DDT spraying campaign said of the effort that "we kicked a dying dog."<ref>Shah, Sonia [http://www.thenation.com/doc/20060417/shah “Don’t Blame Environmentalists for Malaria,”] The Nation. April 2006.</ref> But in countries without these advances, it was critical in their eradication of the disease. In 1955, the [[World Health Organization]] commenced a program to eradicate malaria worldwide, relying largely on DDT. The program was initially highly successful, eliminating the disease in "Taiwan, much of the Caribbean, the Balkans, parts of northern Africa, the northern region of Australia, and a large swath of the South Pacific" and dramatically reducing mortality in Sri Lanka and India.<ref name="Gladwell"> {{Citation | last = Gladwell | first = Malcolm | author-link = Malcolm Gladwell | title = The Mosquito Killer | newspaper = The New Yorker | pages = | year = 2001 | date = July 2, 2001 | url = http://www.gladwell.com/2001/2001_07_02_a_ddt.htm}}.</ref> However resistance soon emerged in many insect populations as a consequence of widespread agricultural use of DDT. In many areas, early victories against malaria were partially or completely reversed, and in some cases rates of transmission even increased.<ref name="pmid7278974">{{cite journal |author=Chapin G, Wasserstrom R |title=Agricultural production and malaria resurgence in Central America and India |journal=Nature |volume=293 |issue=5829 |pages=181–5 |year=1981 |pmid=7278974 |doi=10.1038/293181a0}}</ref> The program was successful in eliminating malaria only in areas with "high socio-economic status, well-organized healthcare systems, and relatively less intensive or seasonal malaria transmission".<ref name="AmJTrop">{{Citation | last = Sadasivaiah | first = Shobha | last2 = Tozan | first2 = Yesim | last3 = Breman | first3 = Joel G. | title = Dichlorodiphenyltrichloroethane (DDT) for Indoor Residual Spraying in Africa: How Can It Be Used for Malaria Control? | journal = Am. J. Trop. Med. Hyg. | volume = 77 | issue = Suppl 6 | pages =249–263 | date =2007 | year =2007 | url = http://www.ajtmh.org/cgi/content/full/77/6_Suppl/249}}</ref> DDT was less effective in tropical regions due to the continuous life cycle of mosquitoes and poor infrastructure. It was not pursued at all in sub-Saharan Africa due to these perceived difficulties, with the result that mortality rates in the area were never reduced to the same dramatic extent, and now constitute the bulk of malarial deaths worldwide, especially following the resurgence of the disease as a result of microbe resistance to drug treatments and the spread of the deadly malarial variant caused by ''[[Plasmodium falciparum]]''. The goal of eradication was abandoned in 1969, and attention was focused on controlling and treating the disease. Spraying programs (especially using DDT) were curtailed due to concerns over safety and environmental effects, as well as problems in administrative, managerial and financial implementation, but mostly because mosquitoes were developing resistance to DDT.<ref name="pmid7278974"/> Efforts were shifted from spraying to the use of [[Mosquito net|bednet]]s impregnated with insecticides and other interventions.<ref name="pmid16125595">{{cite journal |author=Rogan WJ, Chen A |title=Health risks and benefits of bis(4-chlorophenyl)-1,1,1-trichloroethane (DDT) |journal=Lancet |volume=366 |issue=9487 |pages=763–73 |year=2005 |pmid=16125595 |doi=10.1016/S0140-6736(05)67182-6}}</ref><ref name="AmJTrop"/> ===''Silent Spring'' and the U.S. ban=== As early as the 1940s, scientists had begun expressing concern over possible hazards associated with DDT, and in the 1950s the government began tightening some of the regulations governing its use.<ref name=EPA1975/> However, these early events received little attention, and it was not until 1957 when the ''[[New York Times]]'' reported an unsuccessful struggle to restrict DDT use in [[Nassau County, New York]] that the issue came to the attention of the popular naturalist-author, [[Rachel Carson]]. [[William Shawn]], editor of ''[[The New Yorker]]'', urged her to write a piece on the subject, which developed into her famous book ''[[Silent Spring]]'', published in 1962.<ref>Lear, Linda (1997). ''Rachel Carson: Witness for Nature.'' New York: Henry Hoyten.</ref> The book argued that [[pesticide]]s, including DDT, were poisoning both wildlife and the environment and were also endangering human health.<ref name="Silent Spring"/> ''Silent Spring'' was a best seller, and public reaction to it launched the modern [[environmentalism|environmental movement]] in the United States. The year after it appeared, [[John F. Kennedy|President Kennedy]] ordered his Science Advisory Committee to investigate Carson's claims. The report the committee issued "add[ed] up to a fairly thorough-going vindication of Rachel Carson’s Silent Spring thesis," in the words of the journal ''[[Science (journal)|Science]]'',<ref name="pmid17810673">{{cite journal |author=Greenberg DS |title=Pesticides: White House Advisory Body Issues Report Recommending Steps to Reduce Hazard to Public |journal=Science (journal) |volume=140 |issue=3569 |pages=878–879 |year=1963 |month=May |pmid=17810673 |doi=10.1126/science.140.3569.878 |url=http://www.sciencemag.org/cgi/pmidlookup?view=long&pmid=17810673 |accessdate=2008-05-21}} cited in {{cite journal|last=Graham Jr.|first=Frank|title=Nature’s Protector and Provocateur|journal=Audubon Magazine|url=http://audubonmagazine.org/books/editorchoice0709.html}}</ref> and recommended a phaseout of "persistent toxic pesticides".<ref name=Michaels2008>{{cite book|last=Michaels|first=David|title=Doubt Is Their Product: How Industry's Assault on Science Threatens Your Health|publisher=Oxford University Press|location=New York|date=2008|isbn=9780195300673}}</ref> DDT became a prime target of the growing anti-chemical and anti-pesticide movements, and in 1967 a group of scientists and lawyers founded the [[Environmental Defense|Environmental Defense Fund]] (EDF) with the specific goal of winning a ban on DDT. [[Victor Yannacone]], Charles Wurster, Art Cooley and others associated with inception of EDF had all witnessed bird kills or declines in bird populations and suspected that DDT was the cause. In their campaign against the chemical, EDF petitioned the government for a ban and filed a series of lawsuits.<ref>[http://www.time.com/time/magazine/article/0,9171,910111-2,00.html "Sue the Bastards"], ''[[TIME]]'' Oct. 18, 1971</ref> Around this time, [[toxicologist]] [[David Peakall]] was measuring [[Dichlorodiphenyldichloroethylene|DDE]] levels in the eggs of [[peregrine falcons]] and [[California condor]]s and finding that increased levels corresponded with thinner shells. In response to an EDF suit, the U.S. District Court of Appeals in 1971 ordered the [[United States Environmental Protection Agency|EPA]] to begin the de-registration procedure for DDT. After an initial six-month review process, [[William Ruckelshaus]], the Agency's first [[Administrator of the Environmental Protection Agency|Administrator]] rejected an immediate suspension of DDT's registration, citing studies from the EPA's internal staff stating that DDT was not an imminent danger to human health and wildlife.<ref name=EPA1975/> However, the findings of these staff members were criticized, as they were performed mostly by economic entomologists inherited from the [[United States Department of Agriculture]], whom many environmentalists felt were biased towards agribusiness and tended to minimize concerns about human health and wildlife. The decision not to ban thus created public controversy.{{Fact|date=May 2008}} The EPA then held seven months of hearings in 1971-1972, with scientists giving evidence both for and against the use of DDT. In the summer of 1972, Ruckelshaus announced the cancellation of most uses of DDT—an exemption allowed for public health uses under some conditions.<ref name=EPA1975/> Despite the ban on its domestic use, DDT continued to be produced in the US for foreign markets until as late as 1985, when over 300 tonnes were exported.<ref name="ATSDRc5"/> Immediately after the cancellation was announced, both EDF and the DDT manufactures filed suit against the EPA, with the industry seeking to overturn the ban, and EDF seeking a comprehensive ban. The cases were consolidated, and in 1973 the [[U.S. Court of Appeals for the District of Columbia]] ruled that the EPA had acted properly in banning DDT.<ref name=EPA1975/> The U.S. DDT ban took place amid a climate of growing public mistrust of industry, with the [[Surgeon General of the United States|Surgeon General]] issuing a report on [[smoking]] in 1964, the [[Cuyahoga River]] catching fire in 1969, the fiasco surrounding the use of [[diethylstilbestrol]] (DES), and the well-publicized decline in the [[bald eagle]] population.<ref name=Michaels2008/> ===Restrictions on usage=== In the 1970s and 1980s, agricultural use of DDT was banned in most developed countries. DDT was first banned in [[Hungary]] in 1968<ref>{{cite web|url=http://www.fvm.hu/main.php?folderID=1564&articleID=6169&ctag=articlelist&iid=1&part=2| title=Selected passages from the history of the hungarian plant protection administration on the 50th anniversary of establishing the county plant protection stations }}</ref> then in [[Norway]] and [[Sweden]] in 1970 and the US in 1972, but was not banned in the [[United Kingdom]] until 1984. The use of DDT in vector control has not been banned, but it has been largely replaced by less [[Persistent organic pollutant|persistent]], and more expensive, alternative insecticides. The [[Stockholm Convention]], ratified in 2001 and effective as of [[17 May]] [[2004]], outlawed several [[persistent organic pollutant]]s, and restricted the use of DDT to vector control. The Convention was signed by 98 countries and is endorsed by most environmental groups. Recognizing that a total elimination of DDT use in many malaria-prone countries is currently unfeasible because there are few affordable or effective alternatives for controlling malaria, the public health use of DDT was exempted from the ban until such alternatives are developed. Malaria Foundation International states: <blockquote>The outcome of the treaty is arguably better than the status quo going into the negotiations over two years ago. For the first time, there is now an insecticide which is restricted to [[vector control]] only, meaning that the selection of resistant mosquitoes will be slower than before.<ref>{{cite web|url=http://www.malaria.org/DDTpage.html| title=MFI second page| publisher=Malaria Foundation International| accessdate=2006-03-15}}</ref></blockquote> About 1,000 [[tonnes]] of DDT per year is still used today in countries where [[mosquito]]-borne [[malaria]] is a serious health problem.<ref> {{Citation | last = Callaway | first = Ewen | title = Melting glaciers release toxic chemical cocktail | newspaper = New Scientist | year = 2008 | date = May 7, 2008 | url = http://environment.newscientist.com/article/dn13848}}.</ref> Use of DDT in public health to control mosquitoes is primarily done inside buildings and through inclusion in household products and selective spraying; this greatly reduces environmental damage compared to the earlier widespread use of DDT in agriculture. It also reduces the risk of resistance to DDT.<ref>{{cite web| url=http://www.malaria.org/DDTcosts.html| title=Is DDT still effective and needed in malaria control?| publisher=Malaria Foundation International| accessdate=2006-03-15}}</ref> This use only requires a small fraction of that previously used in agriculture; for example, to spray 1,700 homes, the required amount of DDT is estimated to be roughly equal to the amount that might have been used on 0.4 km² (100 acres) of cotton during a typical growing season in the U.S.<ref name="Roberts 1997">{{cite journal | url=http://www.cdc.gov/ncidod/eid/vol3no3/roberts.htm | first=Donald R.| last=Roberts | coauthors=Larry L. Laughlin, Paul Hsheih, and Llewellyn J. Legters | title=DDT, global strategies, and a malaria control crisis in South America | journal=Emerging Infectious Diseases | month=July-September | year=1997 | pages=295–302 | volume=3 | issue=3 | pmid=9284373}}</ref> Despite the worldwide ban on agricultural use of DDT, some farmers in India are known to still use it in crop production.<ref>{{cite news | title = Concern over excessive DDT use in Jiribam fields | publisher = The Imphal Free Press | date = 2008-05-05 | url = http://www.kanglaonline.com/index.php?template=headline&newsid=42015&typeid=1 | accessdate = 2008-05-05 }}</ref> ==Environmental impact== DDT is a [[persistent organic pollutant]] with a [[half life]] of 2-15 years, and is immobile in most soils. Its half life is 56 days in lake water and approximately 28 days in river water. Routes of loss and degradation include runoff, volatilization, photolysis and [[biodegradation]] (aerobic and anaerobic). These processes generally occur slowly. Breakdown products in the soil environment are [[dichlorodiphenyldichloroethylene|DDE]] (1,1-dichloro-2,2-bis(p-dichlorodiphenyl)ethylene) and [[Dichloro-diphenyl-dichloroethane|DDD]] (1,1-dichloro-2,2-bis(p-chlorophenyl)ethane), which are also highly persistent and have similar chemical and physical properties.<ref>[http://www.atsdr.cdc.gov/toxprofiles/tp35-c6.pdf Toxicological Profile for DDT, DDE, and DDD; Chapter 6. ASTDR 2002]</ref> These products together are known as "total DDT". DDT and its breakdown products are transported from warmer regions of the world to the [[Arctic]] by the phenomenon of [[global distillation]], where they then accumulate in the region's [[food web]].<ref>{{cite journal|title=The Grasshopper Effect and Tracking Hazardous Air Pollutants|journal=The Science and the Environment Bulletin|publisher=Environment Canada|issue=May/June 1998|url=http://www.ec.gc.ca/science/sandemay/PrintVersion/print2_e.html}}</ref> DDT and its metabolic products DDE and DDD [[biomagnification|magnify]] through the [[food chain]], with [[apex predator]]s such as raptors having a higher concentration of the chemicals, stored mainly in body fat, than other animals sharing the same environment. In the United States, human blood and fat tissue samples collected in the early 1970s showed detectable levels in all samples. A later study of blood samples collected in the latter half of the 1970s (after the U.S. DDT ban) showed that blood levels were declining further, but DDT or metabolites were still seen in a very high proportion of the samples. Biomonitoring conducted by the CDC as recently as 2002 shows that more than half of subjects tested had detectable levels of DDT or metabolites in their blood,<ref>[http://www.cdc.gov/exposurereport National Report on Exposure to Environmental Chemicals. Centers for Disease Control and Prevention 2005.]</ref> and of the 700+ milk samples tested by the [[USDA]] in 2005, 85% had detectable levels of DDE.<ref>USDA, ''Pesticide Data Program Annual Summary Calendar Year 2005'', November 2006.</ref> DDT is a [[toxicant]] across a certain range of [[phylum|phyla]]. In particular, DDT is a major reason for the decline of the [[bald eagle]] in the 1950s and 1960s<ref>http://www.fws.gov/endangered/i/b/msab0h.html</ref><ref name="pmid17588911"/> as well as the [[brown pelican]]<ref>"Endangered and Threatened Wildlife and Plants; 12-Month Petition Finding and Proposed Rule To Remove the Brown Pelican (Pelecanus occidentalis) From the Federal List of Endangered and Threatened Wildlife; Proposed Rule," Fish and Wildlife Service, U.S. Department of the Interior, February 20, 2008. {{USFR|73|9407}}</ref> and the [[peregrine falcon]]. DDT and its breakdown products are toxic to embryos and can disrupt calcium absorption, thereby impairing eggshell quality.<ref>[http://www.epa.gov/R5Super/ecology/html/toxprofiles.htm#pest Toxicity Profiles, Ecological Risk Assessment | Region 5 Superfund | US EPA<!-- Bot generated title -->]</ref> Studies in the 1960s and 1970s failed to find a mechanism for the hypothesized thinning.<ref name="Fox News, 2006">{{cite web|last=Milloy| first=S. J.|year=2006| url=http://www.foxnews.com/story/0,2933,202447,00.html| title=Bald Eagle-DDT Myth Still Flying High|accessdate=2006-07-10}}</ref> However, more recent studies in the 1990s and 2000s have laid the blame at the feet of [[Dichlorodiphenyldichloroethylene|DDE]].<ref name="Guillette, 2006">{{cite web|last=Guillette| first=Louis J., Jr.|year=2006| url= http://www.ehponline.org/members/2005/8045/8045.pdf | title= Endocrine Disrupting Contaminants |accessdate=2007-02-02}}</ref><ref name="Lundholm, 1997">{{cite journal| last=Lundholm| first=C.E.| year=1997| title= DDE-Induced eggshell thinning in birds| journal=Comp Biochem Physiol C Pharmacol Toxicol Endocrinol| issue=118| doi= 10.1016/S0742-8413(97)00105-9| volume= 118| pages= 113}}</ref> Some studies have shown that although DDE levels have fallen dramatically, eggshell thickness remains 10&ndash;12 percent thinner than before DDT was first used.<ref>[http://www.fws.gov/contaminants/examples/AlaskaPeregrine.cfm Division of Environmental Quality<!-- Bot generated title -->]</ref> DDT is also highly toxic to aquatic life, including [[crayfish]], [[daphnia|daphnids]], [[shrimp|sea shrimp]] and many species of [[fish]]. DDT may be moderately toxic to some [[amphibian]] species, especially in the larval stages. In addition to acute toxic effects, DDT may [[bioaccumulate]] significantly in fish and other aquatic species, leading to long-term exposure to high concentrations. ==Effects on human health==<!-- This section is linked from [[Mickey Slim]] --> The effects of DDT on human health are disputed since studies have yielded conflicting results. ===Toxicity=== ====Acute==== *DDT is classified as "moderately toxic" by the US National Toxicological Program<ref>[http://pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC33482 Pesticideinfo.org]</ref> and "moderately hazardous" by WHO, based on the rat oral [[LD50|LD<sub>50</sub>]] of 113 mg/kg.<ref name = "zvgfrt"/> It is not considered to be acutely toxic, and in fact it has been applied directly to clothes or used in soap.<ref>{{cite web| url=http://www.who.int/docstore/water_sanitation_health/vectcontrol/ch25.htm| title=Vector Control - Methods for Use by Individuals and Communities. Lice| year=1997| author=World Health Organization| accessdate=2006-03-15}}</ref> DDT has on rare occasions been administered orally as a treatment for [[barbiturate]] poisoning.<ref>{{cite journal| journal=Clin Toxicol| year=1973| volume=6| issue=2| pages=147–51| title=Use of oral DDT in three human barbiturate intoxications: hepatic enzyme induction by reciprocal detoxicants| last=Rappolt| first=RT| pmid=4715198}}</ref> ====Chronic==== * Occupational exposure to DDT was associated with reduced verbal attention, visuomotor speed, sequencing, and with increased neuropsychological and psychiatric symptoms in a dose-response pattern (ie, per year of DDT application) in retired workers aged 55–70 years in Costa Rica. DDT or DDE concentrations were not determined in this study.<ref>{{cite journal | author=van Wendel de Joode B, Wesseling C, Kromhout H, Monge P, Garcia M, Mergler D | title=Chronic nervous-system effects of long-term occupational exposure to DDT | journal=Lancet | year=2001 | pages=1014–6 | volume=357 | issue=9261 | pmid=11293598 | doi=10.1016/S0140-6736(00)04249-5}}</ref> * Farmers exposed to DDT occupationally have an increased incidence of non-allergic [[asthma]]. <ref>Anthony J Brown, [http://www.sciam.com/article.cfm?alias=pesticide-exposure-tied-t&chanId=sa003&modsrc=reuters Pesticide Exposure Linked to Asthma], Scientific American, Sept 17, 2007.</ref> * [[Organochlorine]] compounds in general and DDE specifically have been linked to [[diabetes]].<ref>{{Citation | last = Jones | first = Oliver AH | last2 = Maguire | first2 = Mahon L | last3 = Griffin | first3 = Julian L | title = Environmental pollution and diabetes: a neglected association | journal = The Lancet | volume = 371 | issue = | pages = 287–288 | date = January 26, 2008 | year = 2008 | url = http://www.sciencedirect.com/science?_ob=MImg&_imagekey=B6T1B-4RNK38J-B-1&_cdi=4886&_user=4420&_orig=browse&_coverDate=02%2F01%2F2008&_sk=996280390&view=c&wchp=dGLbVtb-zSkzS&md5=49ceb153cf41f91572ac41664bcf057e&ie=/sdarticle.pdf | doi = 10.1016/S0140-6736(08)60147-6 }}</ref> A study of Native Americans exposed to DDE primarily from eating contaminated fish found that elevated blood DDE levels were associated with an increased incidence of diabetes. These results are consistent with previous studies on diabetes incidence and organochlorine exposure.<ref> {{Citation | last = Codru | first = Neculai | author-link = | last2 =| first2 = | author2-link = | title = Diabetes in Relation to Serum Levels of Polychlorinated Biphenyls and Chlorinated Pesticides in Adult Native Americans | journal = Environmental Health Perspectives | volume = 115 | issue = | pages =1442–1447 | date = | year = 2007 | url = http://www.ehponline.org/members/2007/10315/10315.pdf}}</ref> A recent study of Mexican Americans yielded similar results.<ref> {{Citation | last = Cox | first = Shanna | author-link = | last2 = ''et al'' | first2 = | author2-link = | title = Prevalence of Self-Reported Diabetes and Exposure to Organochlorine Pesticides among Mexican Americans: Hispanic Health and Nutrition Examination Survey, 1982–1984 | journal = Environmental Health Perspectives | volume = 115 | issue = | pages = 1747–1752 | date = | year = 2007 | url = http://www.ehponline.org/members/2007/10258/10258.pdf}}</ref> ===Cancer=== *In 1987 the [[EPA]] classified DDT as a class B2 ''probable'' human [[carcinogen]] based on "Observation of tumors (generally of the liver) in seven studies in various mouse strains and three studies in rats. DDT is structurally similar to other probable carcinogens, such as DDD and DDE." Regarding the human carcinogenicity data, they stated "The existing epidemiological data are inadequate. Autopsy studies relating tissue levels of DDT to cancer incidence have yielded conflicting results." <ref>{{cite web| url=http://www.epa.gov/iris/subst/0147.htm#woe|title=Integrated Risk Information System p, p'-Dichlorodiphenyltrichloroethane (DDT) (CASRN 50-29-3) __II.A.1. Weight-of-Evidence Characterization| year=1987| author=US EPA| accessdate=2006-04-18}}</ref> *A study of malaria workers who handled DDT occupationally found an elevated risk of cancers of the [[liver]] and [[biliary tract]]. Another study has found a correlation between DDE and liver cancer in white men, but not for women or black men. An association between DDT exposure and [[pancreatic cancer]] has been demonstrated in a few studies, but other studies have found no association. Several studies have looked for associations between DDT and [[multiple myeloma]], and testicular, prostate, endometrial, and colorectal cancers, but none conclusively demonstrated any association.<ref name="pmid16125595"/> *A Canadian study from 2007 found a positive association between DDE and [[non-Hodgkin Lymphoma]].<ref>{{Citation | last = Spinelli | first =John J. | author-link = | last2 =''et al.'' | first2 = | author2-link = | title = Organochlorines and risk of non-Hodgkin lymphoma | journal = Int. J. Cancer | volume = 121 | issue = 12 | pages = 2767–75 | date = 2007 Dec 15 | year = 2007 | url = http://www3.interscience.wiley.com/cgi-bin/abstract/115807299/ABSTRACT | doi = 10.1002/ijc.23005 | pmid = 17722095 }} </ref> *A recent study in the [[Journal of the National Cancer Institute]] concluded that DDE exposure to may be associated with [[testicular cancer]]. The incidence of [[seminoma]] in men with the highest blood levels of DDE was almost double that of men with the lowest levels of DDE.<ref>{{cite news | last = Dunham | first = Will | title = DDT-related chemical linked to testicular cancer | publisher = Reuters | date = 2008-04-29 | url = http://in.reuters.com/article/worldNews/idINIndia-33310120080429 | accessdate = 2008-04-29}}</ref><ref>{{Citation | last = McGlynn | first = Katherine A. | last2 = Quraishi | first2 = Sabah M. | last3 = ''et al.'' | title = Persistent Organochlorine Pesticides and Risk of Testicular Germ Cell Tumors | journal = Journal of the National Cancer Institute | volume = published ahead of print | date = April 29, 2008 | year = 2008 | url = http://jnci.oxfordjournals.org/cgi/content/abstract/djn101v1 | doi = 10.1093/jnci/djn101 | pages = 663 | pmid = 18445826 }}.</ref> ====Breast cancer==== The question of whether DDT or its metabolites can cause [[breast cancer]] has been the subject of numerous investigations. While individual studies have come to conflicting conclusions, the most recent review of all the evidence concludes that exposure to DDT before puberty increases the risk of breast cancer later in life.<ref name="pmid18557596">{{cite journal |author=Clapp RW, Jacobs MM, Loechler EL |title=Environmental and occupational causes of cancer: new evidence 2005-2007 |journal=Rev Environ Health |volume=23 |issue=1 |pages=1–37 |year=2008 |pmid=18557596 |doi= |url= |accessdate=}}</ref> Until recently, almost all studies measured DDT or DDE blood levels at the time of breast cancer diagnosis or after, and taken as a whole, these studies "do not support the hypothesis that exposure to DDT is an important risk factor for breast cancer."<ref name=EHPBreast>[http://www.ehponline.org/members/2007/10260/10260.pdf DDT and Breast Cancer in Young Women: New Data on the Significance of Age at Exposure], Barbara A. Cohn, Mary S. Wolff, ''et al.'', ''Environ. Health Perspect.,'' 115:1406–1414 (2007).</ref> These types of studies have been extensively reviewed: *In 2007, the journal ''Cancer'' published a review of all of the epidemiological studies on breast cancer and DDT and DDE published between 2000 and 2006. The authors state that "Positive findings for well-controlled studies in the early 1990s of associations between breast cancer risk and the insecticide DDT, its breakdown product DDE, and PCBs prompted additional study. Snedeker reviewed studies of DDT/DDE and dieldrin, concluding that existing research strategies provided conflicting and mostly negative evidence…Updating the picture to 2006 provides…essentially unchanged conclusions for DDT/DDE…[I]n light of these findings, additional study of incident breast cancer in association with biological measures of DDE/DDT levels near the time of diagnosis is not a promising avenue."<ref>{{cite journal| url=http://www3.interscience.wiley.com/cgi-bin/fulltext/114261513/HTMLSTART?CRETRY=1&SRETRY=0| journal= Cancer| issue=| month=| year=2007| pages=|title=Environmental pollutants and breast cancer| first=Julia ''et al.''| last=Green Brody}}</ref> *A 2005 review in ''The Lancet,'' states that "In a study in 1993, 37 breast cancer patients had higher serum DDE concentrations (11.8 μg/L) than controls (7.7 μg/L), and results from several subsequent studies supported such an association. However, large epidemiological studies and subsequent pooled and meta-analyses failed to confirm the association."<ref name="pmid16125595"/> *A 2004 meta-analysis of studies on the association of ''p,p'''-DDE and breast cancer concluded that "Overall, these results should be regarded as a strong evidence to discard the putative relationship between p,p'-DDE and breast cancer risk. Nevertheless, the exposure to DDT during critical periods of human development—from conception to adolescence—and individual variations in metabolizing enzymes of DDT or its derivatives are still important areas to be researched in regard to breast cancer development in adulthood.<ref>[http://www.ehponline.org/members/2003/6492/6492.html ''DDE Burden and Breast Cancer Risk: A Meta-Analysis of the Epidemiologic Evidence.''] Malaquías López-Cervantes, Luisa Torres-Sánchez, Aurelio Tobías, and Lizbeth López-Carrillo, ''EHP,'' 112(2): 207-214, '''2004'''.</ref> In contrast to the studies which measured DDT or DDE late in life, a subsequent study was able to assess DDT exposure early in life and track the breast cancer status of the women later in life. This study, released in 2007, found a strong association between exposure to the ''p,p''-isomer of DDT early in life and breast cancer later in life. Exposure to the ''o,p'''-isomer was negatively correlated with breast cancer (''i.e.'' a protective effect was observed), and no association was observed for DDE. Unlike previous studies, this was prospective study in which blood samples were collected from young California mothers in the 1960s while DDT was still in use, and their breast cancer status was then tracked. In addition to suggesting that exposure to the ''p,p''-isomer of DDT is the more significant risk factor of breast cancer, the study also suggests that the timing of exposure is critical. For the subset of women born more than 14 years prior to the introduction of DDT into US agriculture, there was no association between DDT levels and breast cancer. However, for women born more recently—and thus exposed earlier in life—the most ''p,p''-DDT exposed third of women had a fivefold increase in breast cancer incidence over the least exposed third, after correcting for the protective effect of ''o,p''-DDT.<ref name=EHPBreast/><ref>News media articles about this study: (a) [http://www.contracostatimes.com/health/ci_6524706?nclick_check=1 Exposure to DDT is linked to cancer], Douglas Fischer, ''Contra Costa Times,'' August 8th, 2007. (b) [http://www.latimes.com/news/nationworld/nation/la-na-ddt30sep30,0,3451847.story?coll=la-home-nation Study suggests DDT, breast cancer link], Marla Cone, ''LA Times,'' September 30th, 2007.</ref> ===Developmental and reproductive toxicity=== DDT and its breakdown product DDE, like other organochlorines, have been shown to have [[estrogen|xenoestrogen]]ic activity; meaning they are chemically similar enough to estrogens to trigger hormonal responses in animals. This [[endocrine disruptor|endocrine disrupting]] activity has been observed when DDT is used in laboratory studies involving [[mouse|mice]] and [[rat]]s as test [[research subject|subjects]], and available [[epidemiological]] evidence indicates that these effects may be occurring in humans as a result of DDT exposure. In areas where DDT is used for malaria control, infants can be exposed via breastmilk in levels that exceed the W.H.O's [[acceptable daily intake]] value for DDT.<ref>{{cite journal |author=Bouwman H, Sereda B, Meinhardt HM |title=Simultaneous presence of DDT and pyrethroid residues in human breast milk from a malaria endemic area in South Africa |journal=Environ. Pollut. |volume=144 |issue=3 |pages=902–17 |year=2006 |pmid=16564119 |doi=10.1016/j.envpol.2006.02.002}}</ref> <ref name=Ntow>{{cite journal |author=Ntow WJ, Tagoe LM, Drechsel P, Kelderman P, Gijzen HJ, Nyarko E |title=Accumulation of persistent organochlorine contaminants in milk and serum of farmers from Ghana |journal=Environ. Res. |volume=106 |issue=1 |pages=17–26 |year=2008 |pmid=17931619 |doi=10.1016/j.envres.2007.05.020}}</ref> *A review article in ''[[The Lancet]]'' concludes that, "research has shown that exposure to DDT at amounts that would be needed in malaria control might cause preterm birth and early weaning … toxicological evidence shows [[endocrine disruptor|endocrine-disrupting]] properties; human data also indicate possible disruption in semen quality, menstruation, gestational length, and duration of lactation."<ref name="pmid16125595"/> *Human epidemiological studies suggest that DDT exposure is a risk factor for premature birth and low birth weight, and may harm a mother's ability to [[lactation|breast feed]].<ref name="Rogan&Ragan">{{cite journal |author=Rogan WJ, Ragan NB |title=Evidence of effects of environmental chemicals on the endocrine system in children |journal=Pediatrics |volume=112 |issue=1 Pt 2 |pages=247–52 |year=2003 |pmid=12837917 |doi= |url=http://pediatrics.aappublications.org/cgi/pmidlookup?view=long&pmid=12837917}}</ref> Some researchers argue that these effects may cause increases in infant deaths in areas where DDT is used for malaria control, and thus offset any benefit derived from its anti-malarial effects.<ref>{{cite journal |author=Chen A, Rogan WJ |title=Nonmalarial infant deaths and DDT use for malaria control |journal=Emerging Infect. Dis. |volume=9 |issue=8 |pages=960–4 |year=2003 |pmid=12967494 |doi= |url=http://www.cdc.gov/ncidod/EID/vol9no8/03-0082.htm}}</ref><ref>{{cite journal |author=Roberts D, Curtis C, Tren R, Sharp B, Shiff C, Bate R |title=Malaria control and public health |journal=Emerging Infect. Dis. |volume=10 |issue=6 |pages=1170–1; author reply 1171–2 |year=2004 |pmid=15224677 |doi= |url=http://www.cdc.gov/ncidod/eid/vol10no6/03-0787_03-1116.htm}}</ref><ref>Chen A, Rogan WJ. [http://www.cdc.gov/ncidod/eid/vol10no6/03-0787_03-1116.htm Malaria control and public health (replies).] ''Emerging Infectious Disease'', 10(6):1171-1172, June 2004</ref> A recent study, however, failed to confirm the association between exposure and difficulty breastfeeding.<ref>{{cite journal | last = Cupul-Uicab | first = LA | coauthors = ''et al.'' | title = DDE, a Degradation Product of DDT, and Duration of Lactation in a Highly Exposed Area of Mexico | journal = Environ. Health Perspect. | volume = 116 | issue = 2 | pages = 179–183 | publisher = | location = | date = 2008 | url = http://www.ehponline.org/docs/2007/10550/abstract.html | doi = 10.1289/ehp.10550}}</ref> *Several recent studies demonstrate a link between ''in utero'' exposure to DDT or DDE and [[developmental neurotoxicity]] in humans. For example, a 2006 study conducted by the [[University of California, Berkeley]] suggests children who have been exposed to DDT while in the womb have a greater chance of experiencing development problems,<ref>{{cite web| url=http://news.bbc.co.uk/2/hi/health/5145450.stm|title=DDT 'link' to slow child progress| year=2006| author=BBC| accessdate=2006-07-05}}</ref> and other studies have found that even low-levels of DDT or DDE in [[umbilical cord]] serum at birth are associated with decreased attention at infancy<ref>Sharon K. Sagiv, J. Kevin Nugent, T. Berry Brazelton, Anna L. Choi, Paige E. Tolbert, Larisa M. Altshul, and Susan A. Korrick, 2008. [http://www.ehponline.org/docs/2008/10553/abstract.html Prenatal Organochlorine Exposure and Measures of Behavior in Infancy Using the Neonatal Behavioral Assessment Scale (NBAS)], ''[[Environmental Health Perspectives]]'' 116(5):666-673.</ref> and decreased cognitive skills at 4 years of age.<ref>{{cite journal |author=Ribas-Fitó N, Torrent M, Carrizo D, ''et al'' |title=In utero exposure to background concentrations of DDT and cognitive functioning among preschoolers |journal=Am. J. Epidemiol. |volume=164 |issue=10 |pages=955–62 |year=2006 |pmid=16968864 |doi=10.1093/aje/kwj299}}</ref> Similarly, Mexican researchers have demonstrated a link between DDE exposure in the first trimester of pregnancy and retarded [[psychomotor]] development.<ref>{{cite journal |author=Torres-Sánchez L, Rothenberg SJ, Schnaas L, ''et al'' |title=In utero p,p'-DDE exposure and infant neurodevelopment: a perinatal cohort in Mexico |journal=Environ. Health Perspect. |volume=115 |issue=3 |pages=435–9 |year=2007 |pmid=17431495 |doi=10.1289/ehp.9566}}</ref> *A 2007 study documented decreases in [[semen]] quality among South African men from communities where DDT is used to combat endemic malaria. The researchers found statistically significant correlations between increased levels of DDT or DDE in blood plasma and decreases in several measures of semen quality including ejaculate volume, certain motility parameters, and [[sperm count]].<ref>{{cite journal |author=Aneck-Hahn NH, Schulenburg GW, Bornman MS, Farias P, de Jager C |title=Impaired semen quality associated with environmental DDT exposure in young men living in a malaria area in the Limpopo Province, South Africa |journal=J. Androl. |volume=28 |issue=3 |pages=423–34 |year=2007 |pmid=17192596 |doi=10.2164/jandrol.106.001701}}</ref> The same researchers reported similar results in 2006 from a study of men in Mexico.<ref>{{cite journal |author=De Jager C, Farias P, Barraza-Villarreal A, ''et al'' |title=Reduced seminal parameters associated with environmental DDT exposure and p,p'-DDE concentrations in men in Chiapas, Mexico: a cross-sectional study |journal=J. Androl. |volume=27 |issue=1 |pages=16–27 |year=2006 |pmid=16400073 |doi=10.2164/jandrol.05121}}</ref> A review of earlier studies noted that "Studies of populations with a much lower exposure than that seen in current malaria-endemic areas have shown only weak, inconsistent associations between DDE and testosterone amounts, semen quality, and sperm DNA damage."<ref name="pmid16125595"/> *One recent study suggests that women exposed to DDT while in the womb have more difficulty getting pregnant as adults than non-exposed women. On the other hand, prenatal DDE exposure increased the probability of pregnancy.<ref>{{cite journal |author=Cohn BA, Cirillo PM, Wolff MS, ''et al'' |title=DDT and DDE exposure in mothers and time to pregnancy in daughters |journal=Lancet |volume=361 |issue=9376 |pages=2205–6 |year=2003 |pmid=12842376 |doi=10.1016/S0140-6736(03)13776-2}}</ref> *DDT exposure is associated with early pregnancy loss, a type of [[miscarriage]]. A prospective cohort study of Chinese textile workers found "a positive, monotonic, exposure-response association between preconception serum total DDT and the risk of subsequent early pregnancy losses." <ref>{{cite journal |author=Venners SA, Korrick S, Xu X, ''et al'' |title=Preconception serum DDT and pregnancy loss: a prospective study using a biomarker of pregnancy |journal=Am. J. Epidemiol. |volume=162 |issue=8 |pages=709–16 |year=2005 |pmid=16120699 |doi=10.1093/aje/kwi275}}</ref> The median serum DDE level of study group was lower than that typically observed in women living in homes sprayed with DDT, suggesting that these finding are relevant to the debate about DDT and malaria control. <ref>{{cite journal |author=Longnecker MP |title=Invited Commentary: Why DDT matters now |journal=Am. J. Epidemiol. |volume=162 |issue=8 |pages=726–8 |year=2005 |pmid=16120697 |doi=10.1093/aje/kwi277}}</ref> *A case-control study of [[congenital hypothyroidism]] in Japan concluded that ''in utero'' DDT exposure may affect [[thyroid]] hormone levels and "play an important role in the incidence and/or causation of [[cretinism]]."<ref name="pmid17307219">{{cite journal |author=Nagayama J, Kohno H, Kunisue T, ''et al'' |title=Concentrations of organochlorine pollutants in mothers who gave birth to neonates with congenital hypothyroidism |journal=Chemosphere |volume=68 |issue=5 |pages=972–6 |year=2007 |pmid=17307219 |doi=10.1016/j.chemosphere.2007.01.010 |url=http://linkinghub.elsevier.com/retrieve/pii/S0045-6535(07)00040-9}}</ref> Other studies have also found the DDT or DDE interfere with proper thyroid function.<ref name="pmid17933884">{{cite journal |author=Alvarez-Pedrerol M, Ribas-Fito N, Torrent M, Carrizo D, Grimalt JO, Sunyer J |title=Effects of PCBs, p,p'-DDT, p,p'-DDE, HCB and {beta}-HCH on thyroid function in preschoolers |journal=Occup Environ Med |volume= |issue= |pages= |year=2007 |month=October |pmid=17933884 |doi=10.1136/oem.2007.032763 |url= |accessdate=2008-06-19}}</ref><ref name="pmid18560538">{{cite journal |author=Schell LM, Gallo MV, Denham M, Ravenscroft J, Decaprio AP, Carpenter DO |title=Relationship of Thyroid Hormone Levels to Levels of Polychlorinated Biphenyls, Lead, p,p'- DDE, and Other Toxicants in Akwesasne Mohawk Youth |journal=Environ. Health Perspect. |volume=116 |issue=6 |pages=806–13 |year=2008 |month=June |pmid=18560538 |doi=10.1289/ehp.10490 |url= |accessdate=}}</ref> ==DDT use against malaria== The [[World Health Organization]] estimates there are between 300 million and 500 million cases of malaria every year, resulting in more than 1 million deaths,<ref>2005 WHO [http://www.rbm.who.int/wmr2005/html/exsummary_en.htm World Malaria Report] (see bottom of page)</ref> with about 90% of these deaths occurring in [[Africa]], mostly to children under the age of 5. Most prior use of DDT was in [[agriculture]], but the controlled use of DDT continues to this day for the purposes of public health. Current use for disease control requires only a small fraction of the amounts previously used in agriculture, and at these levels the pesticide is much less likely to cause environmental problems. Residual house spraying involves the treatment of all interior walls and ceilings with insecticide, and is particularly effective against mosquitoes, which favour indoor resting before or after feeding. Advocated as the mainstay of malaria eradication programmes in the late 1950s and 1960s, DDT remains a major component of control programmes in southern African states, though many countries have abandoned or curtailed their spraying activities. [[South Africa]], [[Swaziland]], [[Mozambique]] and [[Ecuador]] are examples of countries that have very successfully reduced malaria infestations with DDT. Indeed, the problems facing health officials in their fight against malaria neither begin nor end with DDT. Experts tie the spread of malaria to numerous factors, including a chronic lack of funds in the countries worst hit by malaria, and the resistance of the malaria parasite itself to the drugs traditionally used to treat the illness.<ref>{{cite web| title=The DDT Ban Myth| url=http://info-pollution.com/ddtban.htm| first=Jim| last= Norton| publisher=Info-pollution.com| accessdate=2006-03-15}}</ref> According to [[Richard Tren]], "Malaria surged through Africa in the 1990s, fueled by resistance to chloroquine and other historically effective drugs."<ref>[http://allafrica.com/stories/200805061135.html Africa: One in Three Malaria Drugs Failing], AllAfrica, 6 May 2008</ref> The growth of resistance to DDT and the fear that DDT may be harmful both to humans and the environment led donor countries and various national governments to restrict or curtail the use of DDT in [[Vector (biology)|vector]] control. At the same time, use of DDT as an agricultural insecticide was often unrestricted, and restrictions were often evaded, especially in developing countries where malaria is rife, so that resistance continued to grow.<ref name="pmid7278974"/> A commentary on the current state of global malaria control was published in the May 2007 issue of the [[Journal of the American Medical Association]]. The authors identify "3 critical factors that are currently absent or in too short supply" for making progress in the fight against malaria: "leadership, management, and money," while making no mention of restrictions limiting the use of DDT. They also single out resistance of the malaria parasite to chloroquine as the cause of increasing malaria mortality in sub-Saharan Africa, not restrictions on DDT.<ref>{{cite journal |author=Feachem RG, Sabot OJ |title=Global malaria control in the 21st century: a historic but fleeting opportunity |journal=JAMA |volume=297 |issue=20 |pages=2281–4 |year=2007 |pmid=17519417 |doi=10.1001/jama.297.20.2281}}</ref> Today there is debate among professionals working on malaria control concerning the appropriate role of DDT. The range of disagreement is relatively narrow: Few believe either that large scale spraying should be resumed or that the use of DDT should be abandoned altogether. The debate focuses on the relative merits of DDT and alternative pesticides as well as complementary use of interior wall spraying, insecticide-treated bed-nets, and other mosquito control techniques. Since the appointment of [[Arata Kochi]] as head of its anti-malaria division, the WHO has shifted its position in this controversy, from primary reliance on bed-nets to a policy more favorable to DDT. Until an announcement made on [[16 September]] [[2006]], the policy had recommended indoor spraying of insecticides in areas of seasonal or episodic transmission of malaria, but a new policy also advocates it where continuous, intense transmission of the disease causes the most deaths.<ref>[http://www.who.int/mediacentre/news/releases/2006/pr50/en/index.html WHO | WHO gives indoor use of DDT a clean bill of health for controlling malaria<!-- Bot generated title -->]</ref> In 2007, the WHO clarified its position, saying it is "very much concerned with health consequences from use of DDT" and reaffirmed its commitment to phasing out the use of DDT.<ref>http://www.yubanet.com/artman/publish/article_56180.shtml</ref> ===Overall effectiveness of DDT against malaria=== In the period from 1934-1955 there were 1.5 million cases of malaria in [[Sri Lanka]], resulting in 80,000 deaths. After the country invested in an extensive anti-mosquito program with DDT, there were only 17 cases reported in 1963. Thereafter the program was halted, and malaria in Sri Lanka rebounded to 600,000 cases in 1968 and the first quarter of 1969. Although the country resumed spraying with DDT, many of the local mosquitoes had acquired resistance to DDT in the interim, presumably because of the continued use of DDT for crop protection, so the program was not nearly as effective as it had been before. Switching to the more-expensive [[malathion]] in 1977 reduced the malaria infection rate to 3,000 by 2004. A recent study notes, "DDT and Malathion are no longer recommended since ''An. culicifacies'' and ''An. subpictus'' has been found resistant."<ref>{{cite journal| journal=Malaria Journal| year=2005| volume=4| pages=8| title=Maps of the Sri Lanka malaria situation preceding the tsunami and key aspects to be considered in the emergency phase and beyond| first=Olivier JT| last=Briët| coauthors=Gawrie NL Galappaththy, Flemming Konradsen, Priyanie H Amerasinghe and Felix P Amerasinghe| doi=10.1186/1475-2875-4-8 | pmid=15676073}}</ref> A 2004 editorial in the ''[[British Medical Journal]]'' argues that the campaign against malaria is failing, that funding of malaria control should therefore be increased, and that use of DDT should be considered since DDT has "a remarkable safety record when used in small quantities for indoor spraying in endemic regions."<ref>{{cite journal| title=Roll Back Malaria: a failing global health campaign| first=Gavin| last=Yamey| journal=BMJ| year=2004| volume=328| pages=1086–1087| month=8 May| doi=10.1136/bmj.328.7448.1086 | pmid=15130956}}</ref> One insecticide supply company states on its website: :''DDT is still one of the first and most commonly used insecticides for residual spraying, because of its low cost, high effectiveness, persistence and relative safety to humans. [...] In the past several years, we supplied DDT 75% [[WDP]] to Madagascar, Ethiopia, Eritrea, Sudan, South Africa, Namibia, Solomon Island, Papua New Guinea, Algeria, Thailand, and Myanmar for Malaria Control project, and won a good reputation from WHO and relevant countries' government.''<ref>{{cite web| url=http://www.treated-bednet.com/agro-chemical.htm| title=Yorkool Chemical - Manufacturer/Supplier of DDT, pyrethroid, and microbial insecticides for Malaria Control| accessdate=2006-03-15}}</ref> According to DDT advocate Donald Roberts, malaria cases increased in [[South America]] after countries in that continent stopped using DDT.<ref name="Roberts 1997"/> Other mosquito-borne diseases are also on the rise. Roger Bate claims that until the 1970s, DDT was used to eradicate the ''[[Aedes aegypti]]'' mosquito from most tropical regions of the Americas. The reinvasion of ''Aedes aegypti'' since has brought devastating outbreaks of [[dengue fever]], [[dengue hemorrhagic fever]], and a renewed threat of urban [[yellow fever]].<ref>{{cite web| last=Bate| first=Roger| month=24 April| year=2001| url=http://www.spiked-online.com/Articles/000000005591.htm| title=Without DDT, malaria bites back| publisher=spiked-online.com| accessdate=2006-03-15}}</ref> ===Mosquito resistance to DDT=== Although the publication of ''Silent Spring'' undoubtedly influenced the U.S. ban on DDT in 1972, the reduced usage of DDT in malaria eradication began the decade before because of the emergence of DDT-resistant mosquitoes. Paul Russell, a former head of the Allied Anti-Malaria campaign, observed in 1956 that eradication programs had to be wary of relying on DDT for too long as "resistance has appeared [after] six or seven years."<ref name="Gladwell"/> In some areas DDT has lost much of its effectiveness, especially in areas such as India where outdoor transmission is the predominant form. According to one article by V.P. Sharma, "The declining effectiveness of DDT is a result of several factors which frequently operate in tandem. The first and the most important factor is vector resistance to DDT. All populations of the main vector, ''An. culicifacies'' have become resistant to DDT." In India, with its outdoor sleeping habits and frequent night duties, "the excito-repellent effect of DDT, often reported useful in other countries, actually promotes outdoor transmission."<ref>{{cite journal|title=DDT: The fallen angel| first=V. P.| last=Sharma| journal=Current Science| volume=85| pages=1532–1537| issue=11| month=10 Devember| year=2003| url=http://www.ias.ac.in/currsci/dec102003/1532.pdf}}</ref> Due to this DDT resistance, in [[Sri Lanka]], parts of India, [[Pakistan]], [[Turkey]] and [[Central America]], DDT has already been replaced by [[organophosphate]] or [[carbamate]] insecticides, ''e.g.'' [[malathion]] or [[bendiocarb]]. <ref name = "Curtis"> ''[http://ipmworld.umn.edu/chapters/curtiscf.htm Control of Malaria Vectors in Africa and Asia]'' C.F.Curtis</ref> According to a pesticide industry newsletter, DDT is obsolete for malarial prevention in India not only owing to concerns over its toxicity, but because it has largely lost its effectiveness. Use of DDT for agricultural purposes was banned in India in 1989, and its use for anti-malarial purposes has been declining. Use of DDT in urban areas of India has halted completely. Food supplies and eggshells of large predator birds still show high DDT levels.<ref>{{cite journal| title=No Future in DDT: A case study of India| last=Agarwal| first=Ravi| journal=Pesticide Safety News| month=May| year=2001}}</ref> Parasitology journal articles confirm that malarial vector mosquitoes have become resistant to DDT and HCH in most parts of India.<ref>{{cite journal | last=Sharma | first=V.P. | title=Current scenario of malaria in India | journal=Parassitologia | year=1999 | pages=349–53 | volume=41 | issue=1-3 | pmid=10697882}}</ref> Nevertheless, DDT is still manufactured and used in India.<ref>{{cite web| url=http://www.unce.unr.edu/publications/SP03/SP0316.pdf| title=DDT and DDE: Sources of Exposure and How to Avoid Them| author=Art Fisher, Mark Walker, Pam Powell| format=PDF| accessdate=2006-03-15}}</ref> One study concludes "The overall results of the study revealed that DDT is still a viable insecticide in indoor residual spraying owing to its effectivity in well supervised spray operation and high excito-repellency factor."<ref name="mrc">[http://www.mrcindia.org/journal/422054.pdf]{{Dead link|date=March 2008}}</ref> The initial appearance of this resistance was largely due to the much greater quantity of DDT which had been used for agricultural spraying, rather than the relatively insignificant amounts used for disease prevention. According to one study which attempted to quantify the lives saved due to banning agricultural use of DDT and thereby slowing the spread of DDT resistance: "Correlating the use of DDT in El Salvador with renewed malaria transmission, it can be estimated that at current rates each kilo of insecticide added to the environment will generate 105 new cases of malaria."<ref name="pmid7278974"/> Advocates for continuing use of DDT against malaria state that "Limited use of DDT for public health has continued to be effective in areas where it is used inside homes. As DDT's chief property is repellency, mosquitoes often avoid the DDT treated homes altogether. In so doing, they avoid the exposure that promotes resistance as well. DDT resistance exists in West Africa and in other malarial areas, such as India. Isolated occurrences of DDT resistance have occurred in South Africa, and South Africa continues to monitor for resistance. As the various Departments of Health that use it carefully control DDT use, it is unlikely that resistance will emerge as a major problem."<ref>[http://www.fightingmalaria.org/faq.aspx#will%20mosquitos%20develop%20resistance Africa Fighting Malaria - Frequently Asked Questions<!-- Bot generated title -->]</ref> Studies of malaria-vector mosquitoes trapped while exiting windows in [[KwaZulu-Natal Province]], [[South Africa]] found susceptibility to 4% DDT (the WHO susceptibility standard), in 63% of the samples, compared to the average of 86.5% in the same species caught in the open. The authors concluded that "Finding DDT resistance in the vector ''An. arabiensis'', close to the area where we previously reported pyrethroid-resistance in the vector ''An. funestus'' Giles, indicates an urgent need to develop a strategy of insecticide resistance management for the malaria control programmes of southern Africa." <ref name="Hargreaves">{{cite journal |author=Hargreaves K, Hunt RH, Brooke BD, ''et al'' |title=Anopheles arabiensis and An. quadriannulatus resistance to DDT in South Africa |journal=Med. Vet. Entomol. |volume=17 |issue=4 |pages=417–22 |year=2003 |pmid=14651656 |doi=10.1111/j.1365-2915.2003.00460.x}}</ref> The avoidance of DDT-sprayed walls by mosquitoes is sometimes touted as a beneficial aspect of DDT.<ref name="mrc"/> For example, a 2007 study published in [[PLoS ONE]] reported that DDT-resistant mosquitoes still avoided DDT-treated huts, while entering huts treated with other insecticides to which they were not resistant. The researchers argued that DDT was the best pesticide for use in IRS (even though it did not afford the most protection from mosquitos out of the three test chemicals) because the others pesticides worked primarily by killing or irritating mosquitoes—modes of action the authors presume mosquitoes will develop resistance to.<ref>{{cite journal |author=Grieco JP, Achee NL, Chareonviriyaphap T, ''et al'' |title=A new classification system for the actions of IRS chemicals traditionally used for malaria control |journal=PLoS ONE |volume=2 |issue=1 |pages=e716 |year=2007 |pmid=17684562 |doi=10.1371/journal.pone.0000716}}</ref> Others have argued that the avoidance of DDT sprayed walls by mosquitoes is detrimental to the actual eradication of the disease.<ref name ="Musawenkosi"/> Unlike other insecticides such as pyrethroids, DDT requires a long period of contact before mosquitoes pick up a lethal dose; however its irritant property makes them fly off before this occurs. "For these reasons, when comparisons have been made, better malaria control has generally been achieved with pyrethroids than with DDT." <ref name = "Curtis"/> ===Residents' resistance to use of DDT=== In areas where resistance from residents prevents a high percentage of the homes being effectively sprayed, the effectiveness of the intervention is greatly reduced.<ref name = "Curtis"/><ref name="Gladwell"/> Many residents resist spraying of DDT for various reasons. For instance, the smell lingers,<ref name = "Thurow"> ''[http://www.mindfully.org/Health/Malaria-New-Strain.htm In Malaria War, South Africa Turns To Pesticide Long Banned in the West]'', Roger Thurow, [[Wall Street Journal]], [[July 26]], [[2001]]</ref> and DDT leaves a stain on the walls.<ref name = "bbc">''[http://news.bbc.co.uk/2/hi/africa/1677073.stm DDT and Africa's war on malaria]'', [[BBC]]</ref><ref name ="Musawenkosi">{{cite journal |author=Mabaso ML, Sharp B, Lengeler C |title=Historical review of malarial control in southern African with emphasis on the use of indoor residual house-spraying |journal=Trop. Med. Int. Health |volume=9 |issue=8 |pages=846–56 |year=2004 |pmid=15303988 |doi=10.1111/j.1365-3156.2004.01263.x}}</ref><ref name = "Curtis"/><ref name = "Thurow"/><ref name = "iea"> ''[http://www.fightingmalaria.org/pdfs/malaria_and_DDT_story_IEA.pdf Malaria and the DDT Story]''</ref> While that stain makes it easier to check whether the room has been sprayed it causes some villagers to avoid spraying of their homes <ref name="Gladwell"/><ref name = "iea"/><ref name = "Tren">''[http://www.cato.org/pubs/pas/pa513.pdf South Africa’s War against Malaria Lessons for the Developing World]'', Richard Tren and Roger Bate, [[Cato Institute]]</ref><ref name = "Curtis"/> or to resurface the wall, which eliminates the residual insecticidal effect of the spraying.<ref name ="Musawenkosi"/><ref name = "iea"/><ref name = "Tren"/> "[[Pyrethroid]]s such as [[deltamethrin]] and [[lambda-cyhalothrin]] are … much more acceptable to householders because they leave no visible deposit on walls… therefore rates of refusal of spraying by householders are lower with pyrethroids than with DDT."<ref name = "Curtis"/> In addition, DDT is not suitable for this type of spraying in Western-style [[plaster]]ed or painted walls, only traditional dwellings with unpainted walls made of mud, sticks, [[dung]], thatch, [[clay]], or cement.<ref name="Hargreaves"/><ref name = "Thurow"/><ref name = "Tren"/><ref name = "iea"/>As rural areas of South Africa become more prosperous, there is a shift towards Western style housing, leaving fewer homes suitable for DDT spraying, and necessitating the use of alternative insecticides.<ref name = "Tren"/> Other villagers object to DDT spraying because it does not kill [[cockroach]]es<ref name = "Curtis"/> or [[bedbug]]s;<ref name ="Musawenkosi"/> rather, it excites such pests making them more active,<ref name = "Thurow"/><ref name = "Tren"/><ref name = "iea"/><ref name = "bbc"/><ref name="Gladwell"/> so that often use of another insecticide is additionally required.<ref name = "Tren"/> Pyrethroids such as deltamethrin and lambdacyhalothrin, on the other hand, are more acceptable to residents because they kill these nuisance insects as well as mosquitoes.<ref name = "Curtis"/> DDT has also been known to kill beneficial insects, such as wasps that kill caterpillars that, unchecked, destroy thatched roofs.<ref name="Gladwell"/> As a result, says Dr. [[Avertino Barreto]], chief of [[infectious disease]] control in [[Mozambique]], resistance to DDT spraying is "homegrown", not due to "pressure from environmentalists". "They only want us to use DDT on poor, rural black people," he says. "So whoever suggests DDT use, I say, 'Fine, I'll start spraying in your house first.' "<ref name = "Thurow"/> ===Human exposure associated with DDT spraying for disease vectors=== In the low income areas where malaria eradication is necessary, it is almost impossible to ensure that DDT intended for disease prevention does not get diverted to use on crops, on a totally unregulated basis. "The consequent insecticidal residues in crops at levels unacceptable for the export trade have been an important factor in recent bans of DDT for malaria control in several tropical countries".<ref name = "Curtis"/> Adding to this problem is a lack of skilled personnel and supervision.<ref name ="Musawenkosi"/> Evidence for exposure to DDT is seen in [[South Africa]]<ref>http://whqlibdoc.who.int/bulletin/1990/Vol68-No6/bulletin_1990_68(6)_761-768.pdf</ref><ref>http://whqlibdoc.who.int/bulletin/1994/Vol72-No6/bulletin_1994_72(6)_921-930.pdf</ref>, where in contrast to areas where DDT use has ceased (even where it was used heavily), in areas where DDT is currently in use ostensibly in small amounts for malaria prevention only, DDT levels in men and women were significantly higher than the allowable daily intake.<ref name = "iea"/> [[Breast milk]] from regions where DDT is used for malaria control contains enough DDT to greatly exceed the allowable daily intake of breast feeding infants.<ref>Bouwman, H. ''et al'',[http://whqlibdoc.who.int/bulletin/1992/Vol70-No2/bulletin_1992_70(2)_241-250.pdf]|1992. Transfer of DDT used in malaria control to infants via breast milk. Bulletin of the [[World Health Organization]], 70:241-250</ref><ref name=Ntow/> These levels have been associated with neurological abnormalities in babies ingesting relatively large quantities of DDT in their milk<ref name = "Curtis"/> although toxicity via this mode of intake has not been proved.<ref name = "iea"/> Some researchers have suggested that the negative health effects of exposure to DDT might outweigh the health benefits afforded by anti-malarial properties. For example, scientists with the US [[National Institute of Environmental Health Sciences]] argued in ''The Lancet'' that "Although DDT is generally not toxic to human beings and was banned mainly for ecological reasons, subsequent research has shown that exposure to DDT at amounts that would be needed in malaria control might cause preterm birth and early weaning, abrogating the benefit of reducing infant mortality from malaria...DDT might be useful in controlling malaria, but the evidence of its adverse effects on human health needs appropriate research on whether it achieves a favourable balance of risk versus benefit."<ref name="pmid16125595"/> ===Criticism of restrictions on DDT use=== There are claims that restrictions on the use of DDT in vector control have resulted in substantial numbers of unnecessary deaths due to [[malaria]]. Estimates for the number of deaths that have been caused by an alleged lack of availability of DDT range from hundreds of thousands, according to Nicholas Kristof,<ref>{{cite journal| url=http://query.nytimes.com/gst/abstract.html?res=F40B1EFB3F580C718DDDAA0894DD404482&n=Top%252fOpinion%252fEditorials%2520and%2520Op%252dEd%252fOp%252dEd%252fColumnists%252fNicholas%2520D%2520Kristof| journal= New York Times| month=March 12| year=2005| title=I Have a Nightmare| first=Nicholas D.| last=Kristof| pages=Section A, Page 15 , Column 1}}</ref> to much higher figures. Robert Gwadz of the [[National Institutes of Health]] said in 2007 that "The ban on DDT may have killed 20 million children."<ref>Finkel, Michael, [http://www7.nationalgeographic.com/ngm/0707/feature1/text4.html "Malaria,"] ''National Geographic'', July 2007</ref> [[Paul Driessen (lobbyist)|Paul Driessen]], author of ''Eco-Imperialism: Green Power, Black Death'',<ref>[http://www.eco-imperialism.com/main.php Eco-Imperialism - Green Power. Black Death.]</ref> argues that the epidemic of malaria in Africa not only takes the lives of 2 million people a year, but leaves those who survive malaria unable to contribute to the economy while sick and more vulnerable to subsequent diseases that might kill them. These arguments have been called "outrageous" by former WHO scientist Socrates Litsios, and May Berenbaum, a professor of entomology at the University of Illinois at Urbana-Champaign, says that "to blame environmentalists who oppose DDT for more deaths than Hitler is worse than irresponsible."<ref>[http://www.salon.com/news/feature/2007/06/29/rachel_carson/ Rachel Carson's birthday bashing], Kirsten Weir, Salon.com, June 29, 2007, accessed July 1, 2007.</ref> In May 2008 article in ''[[Prospect (magazine)|Prospect]]'', [[John Quiggin]] and Tim Lambert write that "the most striking feature of the claim against Carson is the ease with which it can be refuted."<ref name="quig">[http://www.prospect-magazine.co.uk/article_details.php?id=10175 Rehabilitating Carson], John Quiggin & Tim Lambert, ''Prospect'', May 2008.</ref> It has been suggested that DDT treatments were used long enough to eliminate insect-borne diseases in the West, but now that it is only needed in poorer nations in Africa, Asia and elsewhere, it has been banned or otherwise restricted. Some environmental groups have been strongly criticized for trying to ban all use of DDT. According to [[Amir Attaran]], many environmentalist groups fought against the public health exception of DDT in the 2001 [[Stockholm Convention]], against the objections of third world governments and many malaria researchers. "Greenpeace, World Wildlife Fund, Physicians for Social Responsibility and over 300 other environmental organizations advocated for a total DDT ban, starting as early as 2007 in some cases."<ref>[http://www.malaria.org/DDTpage.html Malaria Foundation International<!-- Bot generated title -->]</ref> In an opinion piece in ''Nature Medicine'' he strongly objected to what would have been a [[de facto]] ban and stated: "Environmentalists in rich, developed countries gain nothing from DDT, and thus small risks felt at home loom larger than health benefits for the poor tropics. More than 200 environmental groups, including Greenpeace, Physicians for Social Responsibility and the World Wildlife Fund, actively condemn DDT for being "a current source of significant injury to...humans."<ref>{{cite journal |author=Attaran A, Roberts DR, Curtis CF, Kilama WL |title=Balancing risks on the backs of the poor |journal=Nat. Med. |volume=6 |issue=7 |pages=729–31 |year=2000 |pmid=10888909 |doi=10.1038/77438}}</ref> Criticisms of a ban on DDT often refer specifically to the 1972 US ban (with the implication that this constituted a worldwide ban), while ignoring that DDT has not been banned for public health use in most areas of the world where malaria is endemic.<ref>Dr Alan Lymbery and Professor Andrew Thompson, letter in the ''The Australian'', February 2, 2004. [http://kenethmiles.blogspot.com/2004_02_01_kenethmiles_archive.html#107570569615970184]</ref> Reference is also often made to [[Rachel Carson]]'s ''Silent Spring'' even though she never pushed for a ban on DDT. In fact, she devoted a page of the book to consideration of the relationship between DDT and malarial mosquitoes, with cognizance of the development of resistance in the mosquito, concluding: <blockquote>It is more sensible in some cases to take a small amount of damage in preference to having none for a time but paying for it in the long run by losing the very means of fighting [is the advice given in Holland by Dr Briejer in his capacity as director of the Plant Protection Service]. Practical advice should be "Spray as little as you possibly can" rather than "Spray to the limit of your capacity."</blockquote> However, many African nations have been dissuaded from using DDT in part because the European Union has said that their agricultural exports may not be accepted if spraying was "widespread."<ref>{{cite web| url=http://usinfo.state.gov/af/Archive/2006/Apr/27-513274.html| title=U.S. Senator Does a "Slam Dunk" for Africa Malaria Day| author=[[US Department of State]]}}</ref> In addition, developing nations are typically heavily dependent on aid from agencies that made the aid contingent upon non-usage of DDT. The ''British Medical Journal'' of March 11, 2000, reports that the use of DDT in [[Mozambique]] "was stopped several decades ago, because 80% of the country's health budget came from donor funds, and donors refused to allow the use of DDT."<ref>{{cite journal |author=Sidley P |title=Malaria epidemic expected in Mozambique |journal=BMJ |volume=320 |issue=7236 |pages=669 |year=2000 |pmid=10710569 |doi=10.1136/bmj.320.7236.669}}</ref> For instance, the pro-DDT advocacy group [[Africa Fighting Malaria]] maintains that USAID and some other international donor organizations have refused to fund public health DDT programs.<ref name="Africa Fighting Malaria FAQ">{{cite web| url=http://www.fightingmalaria.org/faq.php| title=Africa Fighting Malaria Frequently Asked Questions| accessdate=2006-03-15}}</ref> Similarly, [[Roger Bate]] of AFM asserts that many countries have been coming under pressure from international health and environment agencies to give up DDT or face losing aid grants, and that Belize and Bolivia have gone on record to say that they gave in to pressure on this issue from the US Agency for International Development.<ref>{{cite journal| url=http://www.cid.harvard.edu/cidinthenews/articles/nr_051401.html| year= 2001| journal=National Review| month=May 14|volume= LIII| issue=9| first=Roger| last=Bate| title=A Case of the DDTs: The war against the war against malaria}}</ref> However, according to the [[USAID]] website, "USAID has never had a “policy” as such either “for” or “against” DDT for IRS. The real change in the past two years has been a new interest and emphasis on the use of Indoor Residual Spraying (IRS) in general – with DDT or any other insecticide – as an effective malaria prevention strategy in tropical Africa."<ref>[http://www.usaid.gov/our_work/global_health/id/malaria/techareas/irs.html USAID Health: Infectious Diseases, Malaria, Technical Area, Prevention and Control, Indoor Residual Spraying.]</ref> USAID's Kent R. Hill states that the agency has been misrepresented: :''USAID strongly supports spraying as a preventative measure for malaria and will support the use of DDT when it is scientifically sound and warranted.''<ref>{{cite web| url=http://www.hillnews.com/thehill/export/TheHill/Comment/LetterstotheEditor/111505.html |title=USAID isn’t against using DDT in worldwide malaria battle |author=[[Kent R. Hill]] |accessdate=2006-04-03|year=2005}}</ref> USAID "favored" DDT alternatives in its funding: :''Contrary to popular belief, USAID does not "ban" the use of DDT in its malaria control programs. From a purely technical point of view in terms of effective methods of addressing malaria, USAID and others have not seen DDT as a high priority component of malaria programs for practical reasons. In many cases, indoor residual spraying of DDT, or any other insecticide, is not cost-effective and is very difficult to maintain. In most countries in Africa where USAID provides support to malaria control programs, it has been judged more cost-effective and appropriate to put US government funds into preventing malaria through insecticide-treated nets, which are every bit as effective in preventing malaria and more feasible in countries that do not have existing, strong indoor spraying programs.''<ref>{{cite web| url=http://www.usaid.gov/our_work/global_health/id/malaria/news/afrmal_ddt.html| title=USAID Health: Infectious Diseases, Malaria, News, Africa Malaria Day, USAID Support for Malaria Control in Countries Using DDT| accessdate=2006-03-15| year=2005}}</ref> ===Alternatives to DDT=== ====DDT versus other insecticides==== Those who advocate for increased use of DDT claim that the alternatives to DDT are generally more expensive, more toxic to humans and not always as effective at controlling malaria and insect-borne diseases, and that the petrochemical companies which patent those alternatives push(ed) for DDT's ban simply for their own profits; DDT had entered the public domain, their patented insecticides have not. Actual data on the cost-effectiveness of DDT versus other insecticides and/or means of fighting malaria is, in fact, lacking. One complicating factor is that the relative costs of various measures vary, depending on geographical location and ease of access, the habits of the particular mosquitoes prevalent in each area, the degrees of resistance to various pesticides exhibited by the mosquitoes, and the habits and compliance of the population, among other factors. [[Organophosphate]] or [[carbamate]] insecticides, ''e.g.'' [[malathion]] or [[bendiocarb]], are considerably more expensive than DDT, and malathion requires more frequent respraying. [[Pyrethroid]]s such as [[deltamethrin]] and [[lambdacyhalothrin]] are also more expensive than DDT, but due to their much greater coverage per unit weight, the net cost per house is about the same.<ref name = "Curtis"/> There are some insecticide alternatives to DDT, including [[methoxychlor]] and [[pyrethroid]]s. The environmental and health effects of alternatives are also under scrutiny. Under the [[Stockholm Convention]], these are issue to be addressed when investigating and promoting alternative chemicals. A recent study has found that DDT as well as [[pyrethroid]] residues, such as [[permethrin]] and [[deltamethrin]], were present in breast milk from a malaria controlled area in [[South Africa]]. The DDT was derived from malaria control, but the pattern of pyrethoid pollution indicated exposure via agricultural use, where mothers frequently work in cotton fields, as well as from domestic use of insecticide dusts in vegetable gardens.<ref>{{cite journal |author=Bouwman H, Sereda B, Meinhardt HM |title=Simultaneous presence of DDT and pyrethroid residues in human breast milk from a malaria endemic area in South Africa |journal=Environ. Pollut. |volume=144 |issue=3 |pages=902–17 |year=2006 |pmid=16564119 |doi=10.1016/j.envpol.2006.02.002 |quote=Even if the pyrethroids were at that stage not used for indoor residual application, the authors indicated that such use would result in pyrethoids being taken up by the mothers and excreted in breast milk, thereby exposing breast feeding infants.}}</ref> ====DDT versus non-chemical vector control==== Before DDT, malaria was successfully eradicated or curtailed in several tropical areas by removing or poisoning the breeding grounds of the mosquitoes or the aquatic habitats of the larva stages, for example by filling or applying oil to places with standing water. These methods have seen little application in Africa for more than half a century.<ref>{{cite journal |author=Killeen GF, Fillinger U, Kiche I, Gouagna LC, Knols BG |title=Eradication of Anopheles gambiae from Brazil: lessons for malaria control in Africa? |journal=Lancet Infect Dis |volume=2 |issue=10 |pages=618–27 |year=2002 |pmid=12383612 |doi=10.1016/S1473-3099(02)00397-3}}</ref> The relative effectiveness of IRS (with DDT or alternative insecticides) versus other malaria control techniques (e.g. bednets or prompt access to anti-malarial drugs) varies greatly and is highly dependent on local conditions.<ref name="AmJTrop"/> A study by the World Health Organization released in January 2008 found that mass distribution of insecticide-treated mosquito nets and artemisinin based drugs cut malaria deaths in half in Rwanda and Ethiopia, countries with very high malaria burdens. IRS with DDT was determined to not have played an important role in the reduction of mortality.<ref>[http://www.who.int/malaria/docs/ReportGFImpactMalaria.pdf Impact of long-lasting insecticidal-treated nets (LLINs) and artemisinin-based combination therapies (ACTs) measured using surveillance data in four African countries.] World Health Organization, Jan. 31, 2008. News article about the study: [http://www.sfgate.com/cgi-bin/article.cgi?f=/c/a/2008/02/01/MN4EUPS3D.DTL&type=health Malaria deaths halved in Rwanda and Ethiopia Better drugs, mosquito nets are the crucial tools], David Brown (Washington Post), ''SF Chronicle'', A-12, Feb. 1, 2008.</ref> [[Vietnam]] is an example of a country that has seen a continued decline in malaria cases after switching in 1991 from a poorly funded DDT-based campaign to a program based on prompt treatment, bednets, and the use of pyrethroid group insecticides. Deaths from malaria dropped by 97%.<ref>http://www.afronets.org/files/malaria.pdf World Health Organization, "A story to be shared: The successful fight against malaria in Vietnam," November 6, 2000.</ref> In Mexico, the use of a range of effective and affordable chemical and non-chemical strategies against malaria has been so successful that the Mexican DDT manufacturing plant ceased production voluntarily, due to lack of demand.<ref name="ddt_ipen.pdf">{{cite web| url=http://www.ems.org/malaria/ddt_ipen.pdf| title=404 error| accessdate=2006-03-15}}</ref> Furthermore, while the increased numbers of malaria victims since DDT usage fell out of favor would, at first glance, suggest a 1:1 correlation, many other factors are known to have contributed to the rise in cases. A review of fourteen studies on the subject in sub-Saharan Africa, covering insecticide-treated nets, residual spraying, chemoprophylaxis for children, chemoprophylaxis or intermittent treatment for pregnant women, a hypothetical vaccine, and changing the first line drug for treatment, found decision making limited by the gross lack of information on the costs and effects of many interventions, the very small number of cost-effectiveness analyses available, the lack of evidence on the costs and effects of packages of measures, and the problems in generalizing or comparing studies that relate to specific settings and use different methodologies and outcome measures. The two cost-effectiveness estimates of DDT residual spraying examined were not found to provide an accurate estimate of the cost-effectiveness of DDT spraying; furthermore, the resulting estimates may not be good predictors of cost-effectiveness in current programmes.<ref>{{cite journal| title=The evidence base on the cost-effectiveness of malaria control measures in Africa| author=C. A. Goodman and A. J. Mills| journal=Health Policy and Planning| volume=14| issue=4| pages=301–312| year=1999| url=http://heapol.oxfordjournals.org/cgi/reprint/14/4/301.pdf | pmid=10787646 | doi = 10.1093/heapol/14.4.301 <!--Retrieved from Yahoo! by DOI bot-->}}</ref> However, a study in Thailand found the cost per malaria case prevented of DDT spraying ($1.87 US) to be 21% greater than the cost per case prevented of [[lambdacyhalothrin]]-treated nets ($1.54 US),<ref>{{cite journal| title=Cost-effectiveness and sustainability of lambdacyhalothrin-treated mosquito nets in comparison to DDT spraying for malaria control in western Thailand| last=Kamolratanakul| first=P.| coauthors=P. Butraporn, M. Prasitisuk, C. Prasittisuk, and K. Indaratna| journal=American Journal of Tropical Medicine and Hygiene| year=2001| volume=65| issue=4| pages=279–84 | pmid=11693869 | doi = 10.1046/j.1365-3156.2001.00700.x <!--Retrieved from Yahoo! by DOI bot-->}}</ref> at very least casting some doubt on the unexamined assumption that DDT was the most cost-effective measure to use in all cases. The director of Mexico's malaria control program finds similar results, declaring that it is 25% cheaper for Mexico to spray a house with synthetic pyrethroids than with DDT.<ref name="ddt_ipen.pdf"/> However, another study in South Africa found generally lower costs for DDT spraying than for impregnated nets.<ref>{{cite journal |author=Goodman CA, Mnzava AE, Dlamini SS, Sharp BL, Mthembu DJ, Gumede JK |title=Comparison of the cost and cost-effectiveness of insecticide-treated bednets and residual house-spraying in KwaZulu-Natal, South Africa |journal=Trop. Med. Int. Health |volume=6 |issue=4 |pages=280–95 |year=2001 |pmid=11348519 |doi=10.1046/j.1365-3156.2001.00700.x}}</ref> A more comprehensive approach to measuring cost-effectiveness or efficacy of malarial control would not only measure the cost in dollars of the project, as well as the number of people saved, but would also take into account the negative aspects of insecticide use on human health and ecological damage. One preliminary study regarding the effect of DDT found that it is likely the detriment to human health approaches or exceeds the beneficial reductions in malarial cases, except perhaps in malarial epidemic situations. It is similar to the earlier mentioned study regarding estimated theoretical infant mortality caused by DDT and subject to the criticism also mentioned earlier.<ref>{{cite journal| url=http://www.jcu.edu.au/jrtph/vol/v04corin.pdf| author= Corin, S. E & Weaver, S.A.| year=2005| title=A risk analysis model with an ecological perspective on DDT and malaria control in South Africa| journal=Journal of Rural and Tropical Public Health| volume=4| pages=21–32 | doi = 10.1046/j.1365-3156.2001.00700.x}}</ref> A study in the Solomon Islands found that "although impregnated bed nets cannot entirely replace DDT spraying without substantial increase in incidence, their use permits reduced DDT spraying."<ref>{{cite journal | last = Over | first = M| authorlink = | coauthors = ''et al'' | title = Impregnated nets or ddt residual spraying? Field effectiveness of malaria prevention techniques in solomon islands, 1993-1999. | journal = Am. J. Trop. Med. Hyg. | volume = 71 | issue = 2 Suppl. | pages = 214–23| publisher = | location = | date = 2004 | url = http://www.ajtmh.org/cgi/content/full/71/2_suppl/214 | doi = | pmid = 15331840 | accessdate = 2008-02-02}}</ref> A comparison of four successful programs against malaria in Brazil, India, Eritrea, and Vietnam does not endorse any single strategy but instead states "Common success factors included conducive country conditions, a targeted technical approach using a package of effective tools, data-driven decision-making, active leadership at all levels of government, involvement of communities, decentralized implementation and control of finances, skilled technical and managerial capacity at national and sub-national levels, hands-on technical and programmatic support from partner agencies, and sufficient and flexible financing."<ref>{{cite journal |author=Barat LM |title=Four malaria success stories: how malaria burden was successfully reduced in Brazil, Eritrea, India, and Vietnam |journal=Am. J. Trop. Med. Hyg. |volume=74 |issue=1 |pages=12–6 |year=2006 |pmid=16407339 |doi=}}</ref> DDT resistant mosquitoes have generally proved susceptible to pyrethroids. Thus far, pyrethroid resistance in ''Anopheles'' has not been a major problem.<ref name = "Curtis"/> ==References== {{reflist|2}} ==External links== {{commonscat|DDT}} ===US Government=== * [http://usinfo.state.gov/products/pubs/carson/berenbaum.htm A Persistent Controversy, a Still Valid Warning] - May Berenbaum, head of the entomology department at University of Illinois, Urbana-Champaign * [http://www.epa.gov/history/topics/ddt/01.htm EPA press release - December 31, 1972] * [http://www.epa.gov/history/topics/ddt/index.htm EPA on DDT] ===Toxicity=== *[http://npic.orst.edu/factsheets/ddttech.pdf DDT Technical Fact Sheet - National Pesticide Information Center] *[http://npic.orst.edu/factsheets/ddtgen.pdf DDT General Fact Sheet - National Pesticide Information Center] *[http://www.atsdr.cdc.gov/tfacts35.html Agency for Toxic Substances and Disease Registry: ToxFAQs for DDT, DDE and DDD] *[http://extoxnet.orst.edu/pips/ddt.htm EXTOXNET: Pesticide Information Profiles&mdash;DDT] *[http://www.scorecard.org/chemical-profiles/summary.tcl?edf_substance_id=50-29-3 Scorecard: The Pollution Information Site&mdash;DDT] *[http://www.loe.org/shows/shows.htm?programID=07-P13-00040 Interview with Barbara Cohn, PhD about DDT and breast cancer] ===Environmental impact=== *[http://jan.ucc.nau.edu/doetqp/courses/env440/lectures/lec25/lec25.html Microbial Degradation of Pesticides] *[http://www.fws.gov/contaminants/Info/DDTNews.html US Fish and Wildlife Service Historic News Releases - DDT] *[http://www.inchem.org/documents/ehc/ehc/ehc83.htm DDT and its Derivatives - Environmental Aspects] *[http://umbbd.ahc.umn.edu/ddt/ddt_map.html Aerobic pathway of DDT metabolization] *[http://umbbd.ahc.umn.edu/ddt2/ddt2_map.html Anaerobic pathway of DDT metabolization] *[http://www.inchem.org/documents/jmpr/jmpmono/v00pr03.htm Pesticide residues in food 2000 : DDT] *[http://www.inchem.org/documents/jmpr/jmpmono/v84pr49.htm Pesticide residues in food&mdash;1984] *[http://www.ces.clemson.edu/ees/lee/organochlorines.html Environmental Fate Evaluation of DDT, Chlordane and Lindane] *[http://www.epa.gov/history/publications/formative6.htm EPA: Pesticides and Public Health] ===Politics and DDT=== *[http://www.reason.com/rb/rb010704.shtml DDT, Eggshells, and Me] Article from [[Reason magazine]] *[http://www.frontpagemag.com/Articles/ReadArticle.asp?ID=23262 DDT: The Bald Eagle Lie] Article from [[FrontPageMag.com]] *[http://www.fair.org/index.php?page=3186 ''Rachel Carson, Mass Murderer?: The creation of an anti-environmental myth.''] Aaron Swartz, ''Extra!'', September/October, 2007. *[http://www.salon.com/news/feature/2007/06/29/rachel_carson/ ''Rachel Carson's Birthday Bashing''], Kirsten Weir, [http://www.salon.com Salon.com], June 29, 2007. ===Malaria and DDT=== *[http://www.washingtonpost.com/wp-dyn/content/article/2005/06/04/AR2005060400130.html "If Malaria's the Problem, DDT's Not the Only Answer"], a ''[[Washington Post]]'' column by [[entomologist]] May Berenbaum *[http://www.vega.org.uk/video/programme/87 'Andrew Spielman, Harvard School of Public Health, discusses environmentally friendly control of Malaria and uses of DDT] Freeview video provided by the Vega Science Trust *[http://info-pollution.com/ddtban.htm The DDT ban myth] *[http://www.iea.org.uk/files/upld-publication26pdf?.pdf Malaria and the DDT Story] *[http://www.sourcewatch.org/index.php?title=Malaria_and_DDT Malaria and DDT] *[http://kenethmiles.blogspot.com/2004_02_01_kenethmiles_archive.html#107570569615970184 Putting Myths to Bed] *The [http://www.fightingmalaria.org/news.php?ID=575 Kill Malarial Mosquitoes NOW!] coalition, a project of the international [[NGO]] [[Africa Fighting Malaria]] *[http://www.globalisationinstitute.org/blog/misc/nets-for-fighting-malaria-20051103120/ Nets for fighting malaria] *[http://www.abc.net.au/news/stories/2008/05/31/2261160.htm Ugandan farmers push for DDT ban. Dated 31 May 2008 ABC News] [[Category:Malaria]] [[Category:Organochloride insecticides]] [[Category:Persistent organic pollutants]] [[Category:Environmental effects of pesticides]] [[Category:Insecticides]] [[Category:IARC Group 2B carcinogens]] [[bn:ডিডিটি]] [[bs:DDT]] [[bg:ДДТ]] [[ca:DDT]] [[cs:DDT]] [[da:DDT]] [[de:Dichlordiphenyltrichlorethan]] [[es:DDT]] [[eo:DDT]] [[fr:Dichlorodiphényltrichloroéthane]] [[ko:DDT]] [[it:Diclorodifeniltricloroetano]] [[he:די די טי]] [[hu:DDT]] [[nl:DDT (insecticide)]] [[ja:DDT]] [[no:DDT]] [[nn:DDT]] [[pl:Dichlorodifenylotrichloroetan]] [[pt:DDT]] [[ru:ДДТ]] [[simple:Dichlorodiphenyltrichloroethane]] [[sk:Dichlórdifenyltrichlóretán]] [[sr:ДДТ]] [[fi:DDT]] [[sv:DDT]] [[tr:DDT]] [[zh-yue:滴滴涕]] [[zh:滴滴涕]]