විකිපීඩියා

"ඩී.ඩී.ටී" හි සංශෝධන අතර වෙනස්කම්

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සිංහල නොවන අන්තර්ගතය
 
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උපද්‍රවයට පත්වූ සත්ව විශේෂ පිළිබඳ නීති පනතත් සමඟ DDT සඳහා වූ ඇමරිකානු තහනම විද්යාඥයින් විසින් දකින ලද්දේ ආසන්න ඇමරිකාවේ bald eagle හි නැවත පැමිණීමේ ප්රධාන සාධකයක් ලෙසය.
 
මුලින්ම සංස්ලේෂණය කරන ලද්දේ 1874දී ය. ඩී.ඩී.ටී. වල [[කෘමිනාශක]] ගුණය 1939 වන තුරුම අනාවරණය කරගෙන නොතිබුණි.
 
 
මුලින්ම සංස්ලේෂණය කරන ලද්දේ 1874දී ය. ඩී.ඩී.ටී. වල [[කෘමිනාශක]] ගුණය 1939 වන තුරුම අනාවරණය කරගෙන නොතිබුණි. and it was used with great success in the second half of [[දෙවන ලෝක යුද්ධය]] to control [[malaria]] and [[typhus]] among civilians and troops. The [[Switzerland|Swiss]] chemist [[Paul Hermann Müller]] 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 used 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, American biologist [[Rachel Carson]] wrote ''[[Silent Spring]]''. The book cataloged the environmental impacts of indiscriminate DDT use in the US and questioned the logic of releasing large amounts of chemicals into the environment without fully understanding their effects on the environment or human health. The book suggested that DDT and other pesticides cause [[cancer]] and that their agricultural use was a threat to wildlife, particularly [[bird]]s. Its publication was a signature event in the birth of the [[Environmentalism|environmental movement]]. It produced a large public outcry that led to a 1972 ban in the US.<ref name="Lear"/> DDT was subsequently banned for agricultural use worldwide under the [[Stockholm Convention]], but limited, controversial use in [[Vector (epidemiology)|disease vector]] [[vector control|control]] continues.<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=2008-06-05}}</ref>
 
Along with the [[Endangered Species Act]], the US DDT ban is cited by scientists as a major factor in the comeback of the [[bald eagle]], the [[national bird of the United States]], from near-[[extinction]] in the contiguous US.<ref name="pmid17588911">
{{cite journal |author=Stokstad E |title=Species conservation. Can the bald eagle still soar after it is delisted? |journal=Science |volume=316 |issue=5832 |pages=1689–90 |year=2007 |month=June |pmid=17588911 |doi=10.1126/science.316.5832.1689 |url=http://www.sciencemag.org/cgi/content/summary/316/5832/1689}}</ref>
 
== Properties and chemistry ==
DDT is an [[organochlorine]], similar in structure to the insecticide [[methoxychlor]] and the [[acaricide]] [[dicofol]]. 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)|oils]]. 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 Anofex, Cezarex, Chlorophenothane, Clofenotane, Dicophane, Dinocide, Gesarol, Guesapon, Guesarol, Gyron, Ixodex, Neocid, Neocidol, and Zerdane.<ref name=EHC9/>
 
=== Isomers and related compounds ===
[[ගොනුව:o,p'-dichlorodiphenyltrichloroethane.svg|thumb|''o,p' ''-DDT, a minor component in commercial DDT.]]
Commercial DDT is a mixture of several closely–related compounds. The major component (77%) is the ''[[Arene substitution patterns|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 [[metabolite]]s and breakdown products 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 |pages= 3958|year=2005 |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 have been produced globally since the 1940s.<ref name="ATSDRc5">[http://www.atsdr.cdc.gov/toxprofiles/tp35.html ''Toxicological Profile: for DDT, DDE, and DDE.''] [[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]], Pennwalt<ref name="Oregon DEQ 2009">
[http://www.deq.state.or.us/lq/ECSI/ecsidetail.asp?seqnbr=398 Environmental Cleanup Site Information Database for Arkema (former Pennwalt) facility], Oregon DEQ, April 2009.</ref> 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. Usage peaked in 1959 at about 36,000 tonnes.<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>
 
Today, 4-5,000 tonnes are used globally each year for the control of malaria and [[visceral leishmaniasis]]. [[India]] is the largest consumer. India, [[China]], and [[North Korea]] are the only countries that still produce and export. Production is reportedly rising.<ref name="DDTBP.1/2">{{
cite web|url=http://www.pops.int/documents/ddt/Global%20status%20of%20DDT%20SSC%2020Oct08.pdf|title=Global status of DDT and its alternatives for use in vector control to prevent disease|last=van den Berg|first=Henk|coauthors=Secretariat of the [[Stockholm Convention]]|date=October 23, 2008|publisher=[[Stockholm Convention]]/[[United Nations Environment Programme]]|accessdate=2008-11-22}}</ref>
 
=== Mechanism of insecticide action ===
In insects it opens [[Sodium channel|sodium ion channels]] in [[neuron]]s, causing them to fire spontaneously, which leads to spasms and eventual death. Insects with certain [[mutation]]s in their sodium channel [[gene]] are resistant to DDT and other similar insecticides. DDT resistance is also conferred by up-regulation of genes expressing [[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>
 
In humans, however, it may affect health through [[genotoxicity]] or [[Endocrine disruptor|endocrine disruption]]. ''See [[#Effects_on_human_health|Effects on human health]]''.
 
== ඉතිහාසය ==
[[ගොනුව:DDT jug.jpg|thumb|right|250px|Commercial product containing 5% DDT]]
First synthesized in 1874 by [[Othmar Zeidler]],<ref name=EHC9/> 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/>
 
=== 1940 හා 1950 දශකවලදී භාවිතය ===
ඩීඩීටී is the best–known of several [[ක්ලෝරීන්]]–containing pesticides used in the 1940s and 1950s. With [[pyrethrum]] in short supply, DDT was used extensively during දෙවන ලෝක යුද්ධය by the [[Allies of දෙවන ලෝක යුද්ධය|Allies]] to control the insect [[Vector (epidemiology)|vectors]] of [[typhus]]—nearly eliminating the disease in many parts of [[යුරෝපය]]. In the [[Pacific Ocean|South Pacific]], it was sprayed aerially for malaria control with spectacular effects. While DDT's chemical and insecticidal properties were important factors in these victories, advances in application equipment coupled with a high degree of organization and sufficient manpower were also crucial to the success of these programs.<ref name=Dunlap>{{
cite book|last=Dunlap|first=Thomas R.|title=DDT: Scientists, Citizens, and Public Policy|publisher=Princeton University Press|location=New Jersey|year=1981|isbn=0-691-04680-8}}</ref> In 1945, it was made available to farmers as an agricultural insecticide,<ref name=EHC9/> and it played a minor role in the final elimination of malaria in Europe and [[North America]].<ref name="Larson"/> By the time DDT was introduced in the U.S., the disease had already been brought under control by a variety of other means.<ref name="OreskesErik M. Conway2010">{{
cite book|last1=Oreskes|first1=Naomi|authorlink1=Naomi Oreskes|last2=Erik M. Conway|first2=Erik M|title=[[Merchants of Doubt]]: How a Handful of Scientists Obscured the Truth on Issues from Tobacco Smoke to Global Warming|edition=First|year=2010|publisher=Bloomsbury Press|location=San Francisco, CA|isbn=1-59691-610-9}}</ref> One [[Centers for Disease Control|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>
 
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"<ref name="Gladwell">{{
Cite news |last = Gladwell | first = Malcolm |author-link = Malcolm Gladwell |title = The Mosquito Killer |newspaper = The New Yorker |date = July 2, 2001 |url = http://www.gladwell.com/2001/2001_07_02_a_ddt.htm}}.</ref> and dramatically reducing mortality in [[Sri Lanka]] and India.<ref name=Gordon/> However widespread agricultural use led to resistant insect populations. In many areas, early victories 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">{{
Cite journal |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=1 December 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 applied at all in [[sub-Saharan Africa]] due to these perceived difficulties. Mortality rates in that area never declined to the same dramatic extent, and now constitute the bulk of malarial deaths worldwide, especially following the disease's resurgence as a result of 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 shifted from spraying to the use of [[Mosquito net|bednets]] impregnated with insecticides and other interventions.<ref name="AmJTrop"/><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>
 
=== ''Silent Spring'' හා ඇ.එ. ජ.හි වාරණය ===
As early as the 1940s, scientists in the U.S. 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. The book argued that [[pesticide]]s, including DDT, were poisoning both wildlife and the environment and were also endangering human health.<ref name="Lear">Lear, Linda (1997). ''Rachel Carson: Witness for Nature.'' New York: Henry Hoyten.</ref>
 
''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 |volume=140 |issue=3569 |pages=878–9 |year=1963 |month=May |pmid=17810673 |doi=10.1126/science.140.3569.878 |url=http://www.sciencemag.org/cgi/pmidlookup?view=long&pmid=17810673 }} 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|year=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>{{cite news |title=Sue the Bastards |url=http://www.time.com/time/magazine/article/0,9171,910111-2,00.html |publisher=[[TIME]] |date=October 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.<ref name=Dunlap/>
 
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/> Immediately after the cancellation was announced, both EDF and the DDT manufacturers 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 amidst a 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/>
 
Some uses of DDT continued under the public health exemption. For example, in June 1979, the California Department of Health Services was permitted to use DDT to suppress flea vectors of [[bubonic plague]].<ref name="urlAEI - Short Publications - The Rise, Fall, Rise, and Imminent Fall of DDT">{{cite web |url=http://www.aei.org/outlook/27063 |title=AEI - Short Publications - The Rise, Fall, Rise, and Imminent Fall of DDT }}</ref> DDT also continued to be produced in the US for foreign markets until as late as 1985, when over 300 tonnes were exported.<ref name="ATSDRc5"/>
 
=== භාවිත පිළිවෙත් ===
In the 1970s and 1980s, agricultural use was banned in most developed countries, beginning with [[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 [[ස්වීඩනය]] in 1970, [[ජර්මනිය]] and the [[US]] in 1972, but not in the [[United Kingdom]] until 1984. Vector control use has not been banned, but it has been largely replaced by less persistent alternative insecticides.
 
The [[Stockholm Convention]], which took effect in 2004, outlawed several [[persistent organic pollutant]]s, and restricted DDT use to [[vector control]]. The Convention has been ratified by more than 160 countries and is endorsed by most environmental groups. Recognizing that total elimination in many malaria-prone countries is currently unfeasible because there are few affordable or effective alternatives, public health use is exempt from the ban pending acceptable alternatives. Malaria Foundation International states, "The outcome of the treaty is arguably better than the status quo going into the negotiations...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>
 
Despite the worldwide ban, agricultural use continues in India<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> North Korea, and possibly elsewhere.<ref name="DDTBP.1/2"/>
 
Today, about 4-5,000 [[tonnes]] each year are used for vector control.<ref name="DDTBP.1/2"/> DDT is applied to the inside walls of homes to kill or repel mosquitoes. This intervention, called [[indoor residual spraying]] (IRS), greatly reduces environmental damage. It also reduces the incidence of DDT resistance.<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> For comparison, treating {{convert|40|ha|acre|abbr=off}} of cotton during a typical U.S. growing season requires the same amount of chemical as roughly 1,700 homes.<ref name="Roberts 1997">{{
cite journal | url=http://www.cdc.gov/ncidod/eid/vol3no3/roberts.htm | first=Donald R.| last=Roberts | 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 | doi=10.3201/eid0303.970305 | last2=Laughlin | first2=LL | last3=Hsheih | first3=P | last4=Legters | first4=LJ | pmc=2627649}}</ref>
 
== Environmental impact ==
[[ගොනුව:DDT to DDD and DDE.svg|thumb|upright=1.8|Degradation of DDT to form DDE (by elimination of HCl, left) and DDD (by reductive dechlorination, right)]]
DDT is a [[persistent organic pollutant]] that is extremely [[hydrophobic]] and strongly absorbed by [[soil]]. Depending on conditions, its soil [[half life]] can range from 22 days to 30 years. Routes of loss and degradation include runoff, volatilization, [[photolysis]] and [[aerobic]] and [[anaerobic]] [[biodegradation]]. When applied to [[aquatic ecosystem]]s it is quickly absorbed by organisms and by soil or it evaporates, leaving little DDT dissolved in the water itself. Its breakdown products and metabolites, DDE and DDD, are also highly persistent and have similar chemical and physical properties.<ref name="ATSDRc5"/> 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|format={{Dead link|date=November 2009}}}}</ref>
 
DDT, DDE, and DDD [[biomagnification|magnify]] through the [[food chain]], with [[apex predator]]s such as [[raptor birds]] concentrating more chemicals than other animals in the same environment. They are very [[lipophilicity|lipophilic]] and are stored mainly in body [[fat]]. DDT and DDE are very resistant to metabolism; in humans, their half-lives are 6 and up to 10 years, respectively. In the United States, these chemicals were detected in almost all human blood samples tested by the [[Centers for Disease Control]] in 2005, though their levels have sharply declined since most uses were banned in the US.<ref name="PineRiver">{{
cite journal|last=Eskenazi|first=Brenda|date=May 4, 2009|title=The Pine River Statement: Human Health Consequences of DDT Use|journal=[[Environmental Health Perspectives|Environ. Health Perspect.]] |url=http://www.ehponline.org/members/2009/11748/11748.pdf}}</ref> Estimated dietary intake has also declined,<ref name="PineRiver"/> although FDA food tests commonly detect it.<ref>
USDA, ''Pesticide Data Program Annual Summary Calendar Year 2005'', November 2006.</ref>
 
Marine macroalgae ([[seaweed]]) help [[bioremediation|reduce]] soil toxicity by up to 80% within six weeks.<ref>{{
cite journal|last=D Kantachote, R Naidu, B Williams, N McClure, M Megharaj, I Singleton |date=2004|title=Bioremediation of DDT-contaminated soil: enhancement by seaweed addition|journal=Journal of Chemical Technology & Biotechnology|volume=79|issue=6|pages=632–8|url=http://www3.interscience.wiley.com/journal/108060819/abstract|accessdate=2009-05-26}}</ref>
 
=== Effects on wildlife and eggshell thinning ===
DDT is toxic to a wide range of animals in addition to insects, including marine animals such as [[crayfish]], [[daphnia|daphnids]], [[shrimp|sea shrimp]] and many species of [[fish]]. It is less toxic to mammals, but may be moderately toxic to some [[amphibian]] species, especially in the [[larvae|larval]] stage. Most famously, it is a reproductive toxicant for certain birds species, and it is a major reason for the decline of the [[bald eagle]],<ref name="pmid17588911"/> [[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> [[peregrine falcon]], and [[osprey]].<ref name="ATSDRc5"/> [[Birds of prey]], [[waterfowl]], and [[passerine|song birds]] are more susceptible to [[eggshell]] thinning than [[chicken]]s and [[Galliformes|related species]], and DDE appears to be more potent than DDT.<ref name="ATSDRc5"/>
 
The biological thinning mechanism is not entirely known, but there is strong evidence that p,p'-DDE inhibits [[calcium ATPase]] in the [[membrane]] of the shell gland and reduces the transport of [[කැල්සියම් කාබනේට්]] from [[blood]] into the eggshell gland. This results in a dose-dependent thickness reduction.<ref name="ATSDRc5"/><ref>{{cite book |author=Walker C.H., ''et al'' |title=Principles of ecotoxicology |publisher=CRC/Taylor & Francis |location=Boca Raton, FL |year=2006 |isbn=0-8493-3635-X |edition=3rd}}</ref><ref name="Guillette, 2006">{{
cite web|last=Guillette| first=Louis J., Jr.|year=2006| url= http://www.ehponline.org/members/2005/8045/8045.pdf |format=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> There is also evidence that o,p'-DDT disrupts female reproductive tract development, impairing eggshell quality later.<ref name="pmid17022422">{{
cite journal |author=Holm L, Blomqvist A, Brandt I, Brunström B, Ridderstråle Y, Berg C |title=Embryonic exposure to o,p'-DDT causes eggshell thinning and altered shell gland carbonic anhydrase expression in the domestic hen |journal=Environ. Toxicol. Chem. |volume=25 |issue=10 |pages=2787–93 |year=2006 |month=October |pmid=17022422 |doi= 10.1897/05-619R.1}}</ref> Multiple mechanisms may be at work, or different mechanisms may operate in different species.<ref name="ATSDRc5"/> Some studies show that although DDE levels have fallen dramatically, eggshell thickness remains 10–12 percent thinner than before DDT was first used.<ref>
[http://www.fws.gov/contaminants/examples/AlaskaPeregrine.cfm Division of Environmental Quality]</ref>
 
== මිනිසාගේ සෞඛ්‍යයට ඇති පලපෑම ==
Potential mechanisms of action on humans are genotoxicity and endocrine disruption. DDT may be directly [[genotoxicity|genotoxic]],<ref name=Cohn07>{{
cite journal |coauthors=Cohn BA, Wolff MS, Cirillo PM, Sholtz RI |title=DDT and breast cancer in young women: new data on the significance of age at exposure |journal=Environ. Health Perspect. |volume=115 |issue=10 |pages=1406–14 |year=2007 |month=October |pmid=17938728 |pmc=2022666 |doi=10.1289/ehp.10260 |last1=Cohn |first1=BA }}</ref> but may also induce [[enzyme]]s to produce other genotoxic intermediates and [[DNA adduct]]s.<ref name=Cohn07/> It is an endocrine disruptor; The DDT metabolite [[Dichlorodiphenyldichloroethylene|DDE]] acts as an [[antiandrogen]] (but not as an [[estrogen]]). p,p'-DDT, DDT's main component, has little or no androgenic or estrogenic activity.<ref name=Cohn07/> Minor component o,p'-DDT has weak estrogenic activity.
 
=== තීව්‍ර විෂවීම ===
DDT is classified as "moderately toxic" by the United States [[National Toxicology Program]] (NTP)<ref>[http://pesticideinfo.org/Detail_Chemical.jsp?Rec_Id=PC33482 Pesticideinfo.org]</ref> and "moderately hazardous" by the [[World Health Organization]] (WHO), based on the rat oral [[LD50|{{chem|LD|50}}]] of 113&nbsp;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> 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| doi=10.3109/15563657308990512}}</ref><!-- not about toxicity-->
 
=== Chronic toxicity ===
==== දියවැඩියාව ====
[[Organochlorine]] compounds, generally, and DDT and DDE, specifically, have been linked to [[diabetes]]. A number of studies from the US, Canada, and Sweden have found that the prevalence of the disease in a population increases with serum DDT or DDE levels.<ref>{{Cite journal |last = Jones |first = Oliver AH |last2 = Maguire |first2 = Mahon L |last3 = Griffin |first3 = Julian L |title = Environmental pollution and diabetes: a neglected association |journal = Lancet |volume = 371 |pages = 287–8 |date = January 26, 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 |format=PDF| doi = 10.1016/S0140-6736(08)60147-6 |pmid = 18294985 |issue = 9609 }}</ref><ref>{{cite journal|last=Turyk|first=Mary|date=March 6, 2009|title=Organochlorine Exposure and Incidence of Diabetes in a Cohort of Great Lakes Sport Fish Consumers|journal=Environ. Health Perspect. |url=http://www.ehponline.org/docs/2009/0800281/abstract.html}}</ref><ref>{{Cite journal |last = Codru |first = Neculai |last2 =Schymura| first2 = MJ | title = Diabetes in Relation to Serum Levels of Polychlorinated Biphenyls and Chlorinated Pesticides in Adult Native Americans |journal =Environ. Health Perspect. | volume = 115 |issue = 10| pages =1442–7 |year = 2007 |url = http://www.ehponline.org/members/2007/10315/10315.pdf|format=PDF |pmid = 17938733 |last3 = Negoita |first3 = S |author4 = Akwesasne Task Force on Environment |last5 = Rej |first5 = R |last6 = Carpenter |first6 = DO |doi = 10.1289/ehp.10315 |pmc = 2022671}}</ref><ref>{{Cite journal |last = Cox |first = Shanna |title = Prevalence of Self-Reported Diabetes and Exposure to Organochlorine Pesticides among Mexican Americans: Hispanic Health and Nutrition Examination Survey, 1982–1984 |journal = Environ. Health Perspect | volume = 115 |issue = 12| pages = 1747–52 |year = 2007 |url = http://www.ehponline.org/members/2007/10258/10258.pdf|format=PDF |pmid = 18087594 |last3 = Narayan |first3 = KM |last4 = Marcus |first4 = M |doi = 10.1289/ehp.10258 |pmc = 2137130 |last2 = Niskar |first2 = AS}}</ref><ref name="pmid19654916">{{cite journal |author=Turyk M, Anderson H, Knobeloch L, Imm P, Persky V |title=Organochlorine exposure and incidence of diabetes in a cohort of Great Lakes sport fish consumers |journal=Environ. Health Perspect. |volume=117 |issue=7 |pages=1076–82 |year=2009 |month=July |pmid=19654916 |doi=10.1289/ehp.0800281 |pmc=2717133}}</ref><ref>{{cite journal|last=Philibert|first=Aline|coauthors=Harold Schwartz and Donna Mergler|date=11 December 2009|title=An Exploratory Study of Diabetes in a First Nation Community with Respect to Serum Concentrations of p,p’-DDE and PCBs and Fish Consumption|journal=Int. J. Environ. Res. Public Health|volume=6|issue=12|pages=3179–89|url=http://www.mdpi.com/1660-4601/6/12/3179|doi=10.3390/ijerph6123179|pmid=20049255|pmc=2800343}}</ref>
 
==== Developmental and reproductive toxicity ====
DDT and DDE, like other organochlorines, have been shown to have [[estrogen|xenoestrogenic]] activity, meaning they are chemically similar enough to estrogens to trigger hormonal responses in animals. This [[endocrine disruptor|endocrine disrupting]] activity has been observed in [[mouse|mice]] and [[rat]] toxicological studies, and available [[epidemiological]] evidence indicates that these effects may be occurring in humans as a result of DDT exposure. These effects may cause developmental and reproductive toxicity:
 
* A review article in ''[[The Lancet]]'' states, "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 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 |url=http://pediatrics.aappublications.org/cgi/pmidlookup?view=long&pmid=12837917 |doi=10.1542/peds.112.1.S1.247 |doi_brokendate=2009-11-27}}</ref> Some 21st century researchers argue that these effects may increase infant deaths, offsetting any anti-malarial benefits.<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 |url=http://www.cdc.gov/ncidod/EID/vol9no8/03-0082.htm}}<br />{{
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 |url=http://www.cdc.gov/ncidod/eid/vol10no6/03-0787_03-1116.htm}}<!-- Includes author reply --></ref>
A 2008 study, however, failed to confirm the association between exposure and difficulty breastfeeding.<ref>{{
cite journal |last = Cupul-Uicab |first = LA |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 |year = 2008 |url = http://www.ehponline.org/docs/2007/10550/abstract.html |doi = 10.1289/ehp.10550 |pmid = 18288315 |last2 = Gladen |first2 = BC |last3 = Hernández-Avila |first3 = M |last4 = Weber |first4 = JP |last5 = Longnecker |first5 = MP |pmc = 2235222}}</ref>
 
* Several recent studies demonstrate a link between ''in utero'' exposure to DDT or DDE and developmental neurotoxicity in humans. For example, a 2006 [[University of California, Berkeley]] study suggests that children exposed while in the womb have a greater chance of development problems,<ref>{{
cite web| url=http://news.bbc.co.uk/2/hi/health/5145450.stm|title=DDT 'link' to slow child progress| author=BBC| accessdate=2006-07-05 | date=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>{{
cite journal |author=Sagiv SK, Nugent JK, Brazelton TB, ''et al.'' |title=Prenatal organochlorine exposure and measures of behavior in infancy using the Neonatal Behavioral Assessment Scale (NBAS) |journal=Environ. Health Perspect. |volume=116 |issue=5 |pages=666–73 |year=2008 |month=May |pmid=18470320 |pmc=2367684 |doi=10.1289/ehp.10553 |url=http://www.ehponline.org/docs/2008/10553/abstract.html}}</ref> and decreased cognitive skills at 4 years of age.<ref>{{
cite journal |author=Ribas-Fitó N, Torrent M, Carrizo D |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 linked first trimester DDE exposure to retarded [[psychomotor]] development.<ref>{{
cite journal |author=Torres-Sánchez L, Rothenberg SJ, Schnaas L |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 |pmc=1849908}}</ref>
 
* Other studies document decreases in semen quality among men with high exposures (generally from IRS).<ref name="pmid20053623">{{
cite journal |author=Jurewicz J, Hanke W, Radwan M, Bonde JP |title=Environmental factors and semen quality |journal=Int J Occup Med Environ Health |volume= 22|issue= 4|pages=1–25 |year=2010 |month=January |pmid=20053623 |doi=10.2478/v10001-009-0036-1 |url=}}</ref><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><ref>{{
cite journal |author=De Jager C, Farias P, Barraza-Villarreal A |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>
 
* Studies generally find that high blood DDT or DDE levels do not increase time to pregnancy (TTP.)<ref name="pmid19092487">{{cite journal |author=Harley KG, Marks AR, Bradman A, Barr DB, Eskenazi B |title=DDT Exposure, Work in Agriculture, and Time to Pregnancy Among Farmworkers in California |journal=J. Occup. Environ. Med. |volume=50 |issue=12 |pages=1335–42 |year=2008 |month=December |pmid=19092487 |doi=10.1097/JOM.0b013e31818f684d |url=http://meta.wkhealth.com/pt/pt-core/template-journal/lwwgateway/media/landingpage.htm?an=00043764-200812000-00003 |pmc=2684791}}</ref> There is some evidence that the daughters of highly exposed women may have more difficulty getting pregnant (i.e. increased TTP).<ref>{{cite journal |author=Cohn BA, Cirillo PM, Wolff MS |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 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 |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.<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 Japanese study of [[congenital hypothyroidism]] 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 |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 |year=2007 |month=October |pmid=17933884 |doi=10.1136/oem.2007.032763 }}</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 |pmc=2430238}}</ref>
 
==== වෙනත් ====
Occupational exposure in agriculture and malaria control has been linked to neurological problems (i.e. Parkinsons)<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> and [[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, September 17, 2007.</ref>
 
=== Carcinogenicity ===
DDT is suspected to cause cancer. The NTP classifies it as "reasonably anticipated" the EPA classifies DDT, DDE, and DDD as class B2 "probables" and the [[International Agency for Research on Cancer]] classifies DDT as a "possible" human [[carcinogen]]. These evaluations are based mainly on the results of animal studies.<ref name="ATSDRc5"/><ref name="pmid16125595"/>
 
Epidemiological evidence (i.e. studies in human populations) indicates that DDT causes cancers of the [[Liver cancer|liver]],<ref name="pmid16125595"/><ref name="PineRiver"/> [[Pancreatic cancer|pancreas]]<ref name="pmid16125595"/><ref name="PineRiver"/> and [[Breast Cancer|breast]].<ref name="PineRiver"/> There is mixed evidence that it contributes to [[leukemia]],<ref name="PineRiver"/> [[lymphoma]]<ref name="PineRiver"/><ref>{{
Cite journal |last = Spinelli |first =John J. |title = Organochlorines and risk of non-Hodgkin lymphoma |journal = Int. J. Cancer |volume = 121 |issue = 12 |pages = 2767–75 |date = 2007-12-15 |url = http://www3.interscience.wiley.com/cgi-bin/abstract/115807299/ABSTRACT |doi = 10.1002/ijc.23005 |pmid = 17722095 |last3 = Weber |first3 = JP |last4 = Connors |first4 = JM |last5 = Gascoyne |first5 = RD |last6 = Lai |first6 = AS |last7 = Brooks-Wilson |first7 = AR |last8 = Le |first8 = ND |last9 = Berry |first9 = BR |last2 = Ng |first2 = CH }}</ref> and [[testicular cancer]].<ref name="pmid16125595"/><ref name="PineRiver"/><ref>{{
Cite journal |last = McGlynn |first = Katherine A. |last2 = Quraishi | first2 = Sabah M. |title = Persistent Organochlorine Pesticides and Risk of Testicular Germ Cell Tumors |journal = Journal of the National Cancer Institute |date = April 29, 2008 |url = http://jnci.oxfordjournals.org/cgi/content/abstract/djn101v1 |doi = 10.1093/jnci/djn101 |pages = 663 |pmid = 18445826 |first3 = BI |last4 = Weber |first4 = JP |last5 = Rubertone |first5 = MV |last6 = Erickson |first6 = RL |issue = 9 |last3 = Graubard |volume = 100 }}.</ref>
 
Epidemiological studies suggest that DDT/DDE '''does not''' cause [[multiple myeloma]],<ref name="pmid16125595"/> or cancers of the [[prostate cancer|prostate]],<ref name="pmid16125595"/> [[endometrial cancer|endometrium]],<ref name="pmid16125595"/><ref name="PineRiver"/> [[colorectal cancer|rectum]],<ref name="pmid16125595"/><ref name="PineRiver"/>[[lung cancer|lung]],<ref name="PineRiver"/> [[bladder cancer|bladder]],<ref name="PineRiver"/> or [[stomach cancer|stomach]].<ref name="PineRiver"/>
 
==== පියයුරු පිලිකා ====
The question of whether DDT or DDE are [[risk factors of breast cancer]] has been repeatedly studied. While individual studies conflict, the most recent reviews of all the evidence conclude that pre-puberty exposure increases the risk of subsequent breast cancer.<ref name="PineRiver"/><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 |pmc=2791455 }}</ref> Until recently, almost all studies measured DDT or DDE blood levels at the time of breast cancer diagnosis or after. This study design has been criticized, since the levels at diagnosis do not necessarily correspond to levels when her cancer started.<ref name="pmid18629310">{{
cite journal |author=Verner MA, Charbonneau M, López-Carrillo L, Haddad S |title=Physiologically based pharmacokinetic modeling of persistent organic pollutants for lifetime exposure assessment: a new tool in breast cancer epidemiologic studies |journal=Environ. Health Perspect. |volume=116 |issue=7 |pages=886–92 |year=2008 |month=July |pmid=18629310 |pmc=2453156 |doi=10.1289/ehp.10917 }}</ref> Taken as a whole such studies "do not support the hypothesis that exposure to DDT is an important risk factor for breast cancer."<ref name=Cohn07/> The studies of this design have been extensively reviewed.<ref name="pmid16125595"/><ref>{{
cite journal |author=Brody JG, Moysich KB, Humblet O, Attfield KR, Beehler GP, Rudel RA |title=Environmental pollutants and breast cancer: epidemiologic studies |journal=Cancer |volume=109 |issue=12 Suppl |pages=2667–711 |year=2007 |month=June |pmid=17503436 |doi=10.1002/cncr.22655 |url=http://www3.interscience.wiley.com/cgi-bin/fulltext/114261513/HTMLSTART?CRETRY=1&SRETRY=0}}</ref><ref>{{
cite journal |author=López-Cervantes M, Torres-Sánchez L, Tobías A, López-Carrillo L |title=Dichlorodiphenyldichloroethane burden and breast cancer risk: a meta-analysis of the epidemiologic evidence |journal=Environ. Health Perspect. |volume=112 |issue=2 |pages=207–14 |year=2004 |month=February |pmid=14754575 |pmc=1241830 |url=http://www.ehponline.org/members/2003/6492/6492.html}}</ref>
 
In contrast, a study published in 2007 strongly associated early exposure (the ''p,p''-isomer) and breast cancer later in life. Unlike previous studies, this [[prospective cohort study]] collected blood samples from young mothers in the 1960s while DDT was still in use, and their breast cancer status was then monitored over the years. In addition to suggesting that the ''p,p''-isomer is the more significant risk factor, the study also suggests that the timing of exposure is critical. For the subset of women born more than 14 years before agricultural use, there was no association between DDT and breast cancer. However, for younger women—exposed earlier in life—the third who were exposed most to ''p, p''-DDT 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=Cohn07/><ref>{{cite news |author=Douglas Fischer |title=Exposure to DDT is linked to cancer |url=http://www.contracostatimes.com/health/ci_6524706?nclick_check=1 |publisher=Contra Costa Times |date=August 8th, 2007 }}</ref><ref>{{cite news |author=Marla Cone |title=Study suggests DDT, breast cancer link |url=http://www.latimes.com/news/nationworld/nation/la-na-ddt30sep30,0,3451847.story?coll=la-home-nation |publisher=LA Times |date=September 30th, 2007 }}</ref> These results are supported by animal studies.<ref name="PineRiver"/>
 
== DDT use against malaria ==
[[Malaria]] remains a major public health challenge in many countries. 2008 WHO estimates were 243 million cases, and 863,000 deaths. About 89% of these deaths occur in [[Africa]], and mostly to children under the age of 5.<ref name=wmr09>
2009 WHO [http://whqlibdoc.who.int/publications/2009/9789241563901_eng.pdf World Malaria Report 2009]</ref> DDT is one of many tools that public health officials use to fight the disease. Its use in this context has been called everything from a "miracle weapon [that is] like [[Kryptonite]] to the mosquitoes,"<ref name=salon/> to "toxic colonialism."<ref>{{
cite journal |author=Paull, John |title=Toxic Colonialism |journal=New Scientist |issue=2628 |pages=25 |date=3 November 2007 |url=http://www.newscientist.com/article/mg19626280.400-toxic-colonialism.html/}}</ref>
 
Before DDT, eliminating mosquito breeding grounds by drainage or poisoning with [[Paris green]] or [[pyrethrum]] was sometimes successful in fighting malaria. In parts of the world with rising living standards, the elimination of malaria was often a collateral benefit of the introduction of window screens and improved sanitation.<ref name="Gladwell"/> Today, a variety of usually simultaneous interventions is the norm. These include [[antimalarial drugs]] to prevent or treat infection; improvements in public health infrastructure to quickly diagnose, sequester, and treat infected individuals; [[mosquito net|bednets]] and other methods intended to keep mosquitoes from biting humans; and [[vector control]] strategies<ref name=wmr09/> such as [[larvacide|larvaciding]] with insecticides, ecological controls such as draining mosquito breeding grounds or introducing fish to eat larvae, and [[indoor residual spraying]] with insecticides, possibly including DDT. IRS involves the treatment of all interior walls and ceilings with insecticides, and is particularly effective against mosquitoes, since many species rest on an indoor wall before or after feeding. DDT is one of 12 WHO–approved IRS insecticides. How much of a role DDT should play in this mix of strategies is still controversial.
 
WHO's anti-malaria campaign of the 1950s and 1960s relied heavily on DDT and the results were promising, though temporary. Experts tie the resurgence of malaria to multiple factors, including poor leadership, management and funding of malaria control programs; poverty; civil unrest; and increased [[irrigation]]. The evolution of resistance to first-generation drugs (e.g. [[chloroquine]]) and to insecticides exacerbated the situation.<ref name="DDTBP.1/2"/><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> Resistance was largely fueled by often unrestricted agricultural use. Resistance and the harm both to humans and the environment led many governments to restrict or curtail the use of DDT in vector control as well as agriculture.<ref name="pmid7278974"/>
 
Once the mainstay of anti-malaria campaigns, as of 2008 only 12 countries used DDT, including India and some southern African states,<ref name=wmr09/> though the number is expected to rise.<ref name="DDTBP.1/2"/>
 
=== Overall effectiveness of DDT against malaria ===
When it was first introduced in දෙවන ලෝක යුද්ධය, DDT was very effective in reducing malaria [[morbidity]] and [[mortality rate|mortality]].<ref name=Dunlap/> The WHO's anti-malaria campaign, which consisted mostly of spraying DDT, was initially very successful as well. For example, in [[Sri Lanka]], the program reduced cases from about 3 million per year before spraying to just 29 in 1964. Thereafter the program was halted to save money, and malaria rebounded to 600,000 cases in 1968 and the first quarter of 1969. The country resumed DDT vector control, but the mosquitoes had acquired resistance in the interim, presumably because of continued agricultural use. The program switched to [[malathion]], which though more expensive, proved effective.<ref name=Gordon>{{
cite book|last=Harrison|first=Gordon A|title=Mosquitoes, Malaria, and Man: A History of the Hostilities Since 1880|publisher=Dutton|year=1978|isbn=0525160256}}</ref>
 
Today, DDT remains on the WHO's list of insecticides recommended for IRS. Since the appointment of [[Arata Kochi]] as head of its anti-malaria division, WHO's policy has shifted from recommending IRS only in areas of seasonal or episodic transmission of malaria, to also advocating it in areas of continuous, intense transmission.<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]</ref> The WHO has reaffirmed its commitment to eventually phasing DDT out, aiming "to achieve a 30% cut in the application of DDT world-wide by 2014 and its total phase-out by the early 2020s if not sooner" while simultaneously combating malaria. The WHO plans to implement alternatives to DDT to achieve this goal.<ref>[http://www.who.int/mediacentre/news/releases/2009/malaria_ddt_20090506/en/index.html Countries move toward more sustainable ways to roll back malaria]</ref>
 
South Africa is one country that continues to use DDT under WHO guidelines. In 1996, the country switched to alternative insecticides and malaria incidence increased dramatically. Returning to DDT and introducing new drugs brought malaria back under control.<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| issue=7448| pmc=406307}}</ref> According to DDT advocate Donald Roberts, malaria cases increased in [[South America]] after countries in that continent stopped using DDT. Research data shows a significantly strong negative relationship between DDT residual house sprayings and malaria rates. In a research from 1993 to 1995, Ecuador increased its use of DDT and resulted in a 61% reduction in malaria rates, while each of the other countries that gradually decreased its DDT use had large increase in malaria rates.<ref name="Roberts 1997"/>
 
=== Mosquito resistance ===
Resistance has greatly reduced DDT's effectiveness. WHO guidelines require that absence of resistance must be confirmed before using the chemical.<ref name="IRS-WHO">
[http://whqlibdoc.who.int/hq/2006/WHO_HTM_MAL_2006.1112_eng.pdf Indoor Residual Spraying: Use of Indoor Residual Spraying for Scaling Up Global Malaria Control and Elimination.] World Health Organization, 2006.</ref> Resistance is largely due to agricultural use, in much greater quantities than required for disease prevention. According to one study that attempted to quantify the lives saved by banning agricultural use and thereby slowing the spread of resistance, "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"/>
 
Resistance was noted early in spray campaigns. Paul Russell, a former head of the [[Allies of දෙවන ලෝක යුද්ධය|Allied]] Anti-Malaria campaign, observed in 1956 that "resistance has appeared [after] six or seven years."<ref name="Gladwell"/> DDT has lost much of its effectiveness in Sri Lanka, [[Pakistan]], [[Turkey]] and [[Central America]], and it has largely 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>
 
In many parts of [[India]], DDT has also largely lost its effectiveness.<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> Agricultural uses were banned in 1989, and its anti-malarial use has been declining. Urban use has halted completely.<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> Nevertheless, DDT is still manufactured and used,<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> and one study had concluded 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">{{
cite journal |author=Sharma SN, Shukla RP, Raghavendra K, Subbarao SK |title=Impact of DDT spraying on malaria transmission in Bareilly District, Uttar Pradesh, India |journal=J Vector Borne Dis |volume=42 |issue=2 |pages=54–60 |year=2005 |month=June |pmid=16161701 }}</ref>
 
Studies of malaria-vector mosquitoes 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 |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>
 
DDT can still be effective against resistant mosquitoes,<ref name=PLoS1/> and the avoidance of DDT-sprayed walls by mosquitoes is an additional benefit of the chemical.<ref name="mrc"/> For example, a 2007 study reported that resistant mosquitoes avoided treated huts. The researchers argued that DDT was the best pesticide for use in IRS (even though it did not afford the most protection from mosquitoes out of the three test chemicals) because the others pesticides worked primarily by killing or irritating mosquitoes—encouraging the development of resistance to these agents.<ref name=PLoS1>{{cite journal |author=Grieco JP, Achee NL, Chareonviriyaphap T |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 |pmc=1934935}}</ref> Others argue that the avoidance behavior slows the eradication of the disease.<ref name="Musawenkosi"/> Unlike other insecticides such as pyrethroids, DDT requires long exposure to accumulate a lethal dose; however its irritant property shortens contact periods. "For these reasons, when comparisons have been made, better malaria control has generally been achieved with pyrethroids than with DDT."<ref name = "Curtis"/> 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 December| year=2003| url=http://www.ias.ac.in/currsci/dec102003/1532.pdf|format=PDF}}</ref>
 
=== Residents' concerns ===
{{මූලික|Indoor residual spraying#Residents's opposition to IRS}}
 
For IRS to be effective, at least 80% of homes and barns in an area must be sprayed.<ref name="IRS-WHO"/> Lower coverage rates can jeopardize program effectiveness. Many residents resist DDT spraying, objecting to the lingering smell, stains on walls, and may exacerbate problems with other insect pests.<ref name = "Curtis"/><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 = "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> [[Pyrethroid]] insecticides (e.g. [[deltamethrin]] and [[lambda-cyhalothrin]]) can overcome some of these issues, increasing participation.<ref name = "Curtis"/>
 
=== Human exposure ===
People living in areas where DDT is used for IRS have high levels of the chemical and its breakdown products in their bodies. Compared to contemporaries living where DDT is not used, [[South Africa]]ns living in sprayed homes have levels that are several orders of magnitude greater.<ref name="PineRiver"/> [[Breast milk]] in regions where DDT is used against malaria greatly exceeds the allowable standards for breast-feeding infants.<ref name="Bouwman H, Sereda B, Meinhardt HM 2006 902–17">{{
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><ref>{{
cite journal |author=Spicer PE, Kereu RK |title=Organochlorine insecticide residues in human breast milk: a survey of lactating mothers from a remote area in Papua New Guinea |journal=Bull Environ Contam Toxicol |volume=50 |issue=4 |pages=540–6 |year=1993 |month=April |pmid=8467139 }}</ref> These levels are associated with neurological abnormalities in babies.<ref name = "Curtis"/><ref name="Bouwman H, Sereda B, Meinhardt HM 2006 902–17"/><ref name="Ntow"/>
 
Most studies of DDT's human health effects have been conducted in developed countries where DDT is not used and exposure is relatively low. Many experts urge that alternatives be used instead of IRS.<ref name="pmid16125595"/><ref name="PineRiver"/> Epidemiologist Brenda Eskenazi argues, "We know DDT can save lives by repelling and killing disease-spreading mosquitoes. But evidence suggests that people living in areas where DDT is used are exposed to very high levels of the pesticide. The only published studies on health effects conducted in these populations have shown profound effects on male fertility. Clearly, more research is needed on the health of populations where indoor residual spraying is occurring, but in the meantime, DDT should really be the last resort against malaria rather than the first line of defense."<ref>{{
cite news|url=http://www.sciencedaily.com/releases/2009/05/090504122058.htm|title=Unprecedented Use Of DDT Concerns Experts|last=Science Daily|date=May 9, 2009|publisher=ScienceDaily.com|accessdate=2009-05-30}}</ref>
 
Illegal diversion to agriculture is also a concern, as it is almost impossible to prevent, and its subsequent use on crops is uncontrolled. For example, DDT use is widespread in Indian agriculture,<ref>{{
cite news|url=http://economictimes.indiatimes.com/Markets/Commodities/Pesticide-level-in-veggies-fruits-rises/articleshow/4637527.cms|title=Pesticide level in veggies, fruits rises|last=Jayashree|first=Jayashree|date=June 10, 2009|publisher=Economic Times|accessdate=2009-06-10}}</ref> particularly [[mango]] production,<ref>{{
cite journal|last=SANJANA|date=June 13, 2009|title=A Whole Fruit|journal=Tehelka Magazine|volume=6|issue=23|url=http://www.tehelka.com/story_main42.asp?filename=cr130609a_whole.asp}}</ref> and is reportedly used by librarians to protect books.<ref>{{
cite news|url=http://www.indianexpress.com/news/State-public-libraries-gasp-for-breath/472785|title=State public libraries gasp for breath|last=Chakravartty|first=Anupam|date=June 8, 2009|publisher=Indian Express|accessdate=2009-06-08}}</ref> Other example include Ethiopia, where DDT intended for malaria control is reportedly being used in coffee production,<ref>{{
cite journal|last=Katima|first=Jamidu|date=June 2009|title=African NGOs outline commitment to malaria control without DDT|journal=Pesticides News|issue=84|pages=5}}</ref> and Ghana where it is used for fishing."<ref>{{
cite web|url=http://www.ghananewsagency.org/s_social/r_9596/|title=Ministry moves to check unorthodox fishing methods|last=Ghana News Agency|date=November 17, 2009|publisher=Ghana News Agency|accessdate=2009-11-18}}</ref><ref>{{cite news|url=http://news.myjoyonline.com/news/201004/45316.asp|title=Northern fisherfolks complain of committee’s harassment|last=Appiah|first=Samuel |date=27 April 2010|publisher=Joy Online|accessdate=27 April 2010}}</ref> The residues in crops at levels unacceptable for export have been an important factor in recent bans in several tropical countries.<ref name = "Curtis"/> Adding to this problem is a lack of skilled personnel and supervision.<ref name="Musawenkosi"/>
 
=== Criticism of restrictions on DDT use ===
Critics claim that restricting DDT in vector control have caused unnecessary deaths due to malaria. Estimates range from hundreds of thousands,<ref>{{
cite news| url=http://query.nytimes.com/gst/abstract.html?res=F40B1EFB3F580C718DDDAA0894DD404482&n=Top%252fOpinion%252fEditorials%2520and%2520Op%252dEd%252fOp%252dEd%252fColumnists%252fNicholas%2520D%2520Kristof| publisher= 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| nopp=true}}</ref> to much higher figures. Robert Gwadz of the [[National Institutes of Health]] said in 2007, "The ban on DDT may have killed 20 million children."<ref>
{{cite news |author=Finkel, Michael |title=Malaria |url=http://www7.nationalgeographic.com/ngm/0707/feature1/text4.html |publisher=National Geographic |date=July 2007 }}</ref> These arguments have been dismissed as "outrageous" by former WHO scientist Socrates Litsios. May Berenbaum, [[University of Illinois]] entomologist, says, "to blame environmentalists who oppose DDT for more deaths than Hitler is worse than irresponsible."<ref name=salon>
{{cite news |author=Kirsten Weir |title=Rachel Carson's birthday bashing |url=http://www.salon.com/news/feature/2007/06/29/rachel_carson/ |publisher=Salon.com |date=June 29, 2007 |accessdate=2007-07-01 }}</ref> Investigative journalist Adam Sarvana and others characterize this notion as a "myth" promoted principally by [[Roger Bate]] of the pro-DDT advocacy group [[Africa Fighting Malaria]] (AFM).<ref name="NRNS">{{
cite news|url=http://www.nrns.org/index.php?option=com_content&view=article&id=51:bate-and-switch-how-a-free-market-magician-manipulated-two-decades-of-environmental-science-|title=Bate and Switch: How a free-market magician manipulated two decades of environmental science|last=Sarvana|first=Adam|date=May 28, 2009|publisher=Natural Resources New Service|accessdate=2009-06-02}}</ref><ref name=Guts>{{
cite book|last=Gutstein|first=Donald|title=Not a Conspiracy Theory: How Business Propaganda Hijacks Democracy|publisher=Key Porter Books|date=November 24, 2009|isbn=1554701910}}. Relevant section excepted at: {{
cite news|url=http://thetyee.ca/Mediacheck/2010/01/22/DDTPropaganda/|title=Inside the DDT Propaganda Machine|last=Gutstein|first=Donald|date=January 22, 2010|publisher=The Tyee|accessdate=22 January 2010}}</ref>
Criticisms of a DDT "ban" often specifically reference the 1972 US ban (with the erroneous implication that this constituted a worldwide ban and prohibited use of DDT in vector control). Reference is often made to [[Rachel Carson]]'s ''Silent Spring'' even though she never pushed for a ban on DDT. [[John Quiggin]] and Tim Lambert wrote, "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> Carson actually devoted a page of her book to considering the relationship between DDT and malaria, warning of the [[evolution]] of DDT resistance in mosquitoes and 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>
<!--what can she have meant by "small amount of damage" and who did she think was spraying "to the limit of your capacity"?-->
 
According to [[Amir Attaran]] and Roger Bate, many environmental groups fought against the public health exception in the 2001 [[Stockholm Convention]], over the objections of third world governments and many malaria researchers. Attaran strongly objected to an outright ban, writing, "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..."<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>
 
It has also been alleged that donor governments and agencies have refused to fund DDT spraying, or made aid contingent upon not using DDT. According to a report in the ''British Medical Journal'', 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 |pmc=1117705}}</ref> Roger Bate asserts, "many countries have been coming under pressure from international health and environment agencies to give up DDT or face losing aid grants: Belize and Bolivia are on record admitting they gave in to pressure on this issue from [USAID]."<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>
 
The [[United States Agency for International Development]] (USAID) has been the focus of much criticism. While the agency is currently funding the use of DDT in some African countries,<ref name=USAID>{{
cite web|url=http://www.usaid.gov/our_work/global_health/id/malaria/techareas/irs.html|title=USAID Health: Infectious Diseases, Malaria, Technical Areas, Prevention and Control, Indoor Residual Spraying|publisher=USAID|accessdate=2008-10-14}}</ref> in the past it did not. When [[John Stossel]] accused USAID of not funding DDT because it wasn't "politically correct," Anne Peterson, the agency's assistant administrator for global health, replied that "I believe that the strategies we are using are as effective as spraying with DDT ... So, politically correct or not, I am very confident that what we are doing is the right strategy."<ref>{{
cite news|url=http://abcnews.go.com/2020/Stossel/story?id=1898820|title=Excerpt: 'Myths, Lies, and Downright Stupidity'|last=Stossel|first=John|date=November 16, 2007|publisher=ABC News|accessdate=2008-10-14}}</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> The Agency's website states that "USAID has never had a 'policy' as such either 'for' or 'against' DDT for IRS. The real change in the past two years [2006/07] has been a new interest and emphasis on the use of IRS in general—with DDT or any other insecticide—as an effective malaria prevention strategy in tropical Africa."<ref name=USAID/> The website further explains that in many cases alternative malaria control measures were judged to be more cost-effective that DDT spraying, and so were funded instead.<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 ===
==== Other insecticides ====
{{මූලික|Indoor residual spraying}}
Advocates of increased use of DDT in IRS claim that alternative insecticides are more expensive, more toxic, or not as effective. As discussed above, susceptibility of mosquitoes to DDT varies geographically. The same is true for alternative insecticides, so its relative effectiveness varies. Toxicity and cost-effectiveness comparisons lack data. Relative insecticide costs vary by location and ease of access, the habits of the local mosquitoes, the degrees of resistance exhibited by the mosquitoes, and the habits and compliance of the population, among other factors. The choice of insecticide has little impact on the total cost of a round of spraying, since product costs are only a fraction of campaign costs. IRS coverage needs to be maintained throughout the malaria season, making DDT's relatively long life an important cost savings.
 
[[Organophosphate]] and [[carbamate]] insecticides, ''e.g.'' [[malathion]] and [[bendiocarb]], respectively, are more expensive than DDT per kilogram and are applied at roughly the same dosage. [[Pyrethroid]]s such as [[deltamethrin]] are also more expensive than DDT, but are applied more sparingly (0.02-0.3 g/m<sup>2</sup> vs 1-2 g/m<sup>2</sup>), so the net cost per house is about the same over 6 months.<ref name="AmJTrop"/>
 
==== Non-chemical vector control ====
Before DDT, malaria was successfully eradicated or curtailed in several tropical areas by removing or poisoning mosquito breeding grounds and larva habitats, for example by filling or applying oil to 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 WHO study 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 high malaria burdens. IRS with DDT did not play an important role in mortality reduction in these countries.<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, January 31, 2008.</ref><ref>
[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, February 1, 2008.</ref>
 
[[Vietnam]] has enjoyed declining malaria cases and a 97% mortaility reduction after switching in 1991 from a poorly funded DDT-based campaign to a program based on prompt treatment, bednets, and pyrethroid group insecticides.<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, effective and affordable chemical and non-chemical strategies against malaria have been so successful that the Mexican DDT manufacturing plant ceased production due to lack of demand.<ref name="PMC1119118">{{
cite web| url=http://www.ipen.org/ipenweb/documents/work%20documents/ddt_ipenreport_english.pdf|title=DDT & Malaria| accessdate=2009-03-11}}</ref>
 
While the increased numbers of malaria victims since DDT usage collapsed document its value, many other factors 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 front–line drug 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 programs.<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 |format=PDF| pmid=10787646 | doi = 10.1093/heapol/14.4.301}}</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 [[lambda-cyhalothrin]]–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.| 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| last2=Butraporn| first2=P| last3=Prasittisuk| first3=M| last4=Prasittisuk| first4=C| last5=Indaratna| first5=K| last6=Gumede| first6=J. K.}}</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="PMC1119118"/> 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 consider ecological damage and negative aspects of insecticide use on human health. 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|format=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 |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 |year=2004 |url=http://www.ajtmh.org/cgi/content/full/71/2_suppl/214 |pmid=15331840 |last2=Bakote'e |first2=B |last3=Velayudhan |first3=R |last4=Wilikai |first4=P |last5=Graves |first5=PM}}</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 }}</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"/>
 
== මේවාත් බලන්න ==
* [[:en:DDT in Australia]]
* [[:en:DDT in New Zealand]]
* [[:en:DDT in the United States]]
* [[Mickey Slim]], a short-lived cocktail that combined [[gin]] with a pinch of DDT.
* [[:en:Operation Cat Drop]]
 
== මූලාශ්‍ර ==
{{Reflist|2}}
 
== External links ==
{{Commons category|DDT}}
;Toxicity
 
* [http://npic.orst.edu/factsheets/ddttech.pdf DDT Technical Fact Sheet - National Pesticide Information Center]
* [http://extoxnet.orst.edu/pips/ddt.htm EXTOXNET: Pesticide Information Profiles—DDT]
* [http://www.scorecard.org/chemical-profiles/summary.tcl?edf_substance_id=50-29-3 Scorecard: The Pollution Information Site—DDT]
* [http://www.loe.org/shows/shows.htm?programID=07-P13-00040 Interview with Barbara Cohn, PhD about DDT and breast cancer]
* [http://www.inchem.org/documents/jmpr/jmpmono/v00pr03.htm Pesticide residues in food 2000 : DDT]
 
;Politics and DDT
* [http://www.reason.com/rb/rb010704.shtml DDT, Eggshells, and Me] Article from [[Reason magazine]] by [[Ronald Bailey]].
* [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.
 
;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.abc.net.au/news/stories/2008/05/31/2261160.htm Ugandan farmers push for DDT ban. Dated 31 May 2008 ABC News]
 
{{insecticides}}
 
{{DEFAULTSORT:Ddt}}
[[ප්‍රවර්ගය:DDT]]
[[ප්‍රවර්ගය:Endocrine disruptors]]
[[ප්‍රවර්ගය:Pesticides]]
[[ප්‍රවර්ගය:Malaria]]
[[ප්‍රවර්ගය:Organochloride insecticides]]
[[ප්‍රවර්ගය:Persistent organic pollutants]]
[[ප්‍රවර්ගය:Environmental effects of pesticides]]
[[ප්‍රවර්ගය:IARC Group 2B carcinogens]]
[[ප්‍රවර්ගය:රසායන විද්‍යාව]]
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