Editing DDT (section)

==Environmental impact==
[[File:DDT to DDD and DDE.svg|thumb|upright=1.8|class=skin-invert-image|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 readily [[Adsorption|adsorbed]] to [[soil]]s and [[sediment]]s, which can act both as sinks and as long-term sources of exposure affecting organisms.<ref name=EHC83/> Depending on environmental conditions, its soil [[half-life]] can range from 22 days to 30 years. Routes of loss and degradation include runoff, volatilization, [[photolysis]] and [[aerobic organism|aerobic]] and [[Anaerobic digestion|anaerobic]] [[biodegradation]]. Due to [[hydrophobic]] properties, in [[aquatic ecosystem]]s DDT and its metabolites are absorbed by aquatic organisms and adsorbed on suspended particles, leaving little DDT dissolved in the water (however, its half-life in aquatic environments is listed by the [[National Pesticide Information Center]] as 150 years<ref>{{cite web|title=DDT (Technical Fact Sheet)|url=http://npic.orst.edu/factsheets/archive/ddttech.pdf|access-date=1 August 2018|archive-date=February 19, 2018|archive-url=https://web.archive.org/web/20180219141527/http://npic.orst.edu/factsheets/archive/ddttech.pdf|url-status=live}}</ref>). Its breakdown products and metabolites, DDE and DDD, are also persistent and have similar chemical and physical properties.<ref name="ATSDRc5"/> DDT and its breakdown products are transported from warmer areas 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 |url-status=dead |archive-url=https://web.archive.org/web/20040928235911/http://www.ec.gc.ca/science/sandemay/printversion/print2_e.html |archive-date=September 28, 2004 }}</ref>

Medical researchers in 1974 found a measurable and significant difference in the presence of DDT in human milk between mothers who lived in [[New Brunswick]] and mothers who lived in [[Nova Scotia]], "possibly because of the wider use of insecticide sprays in the past".<ref>{{Cite journal |last1=Musial |first1=C. J. |last2=Hutzinger |first2=O. |last3=Zitko |first3=V. |last4=Crocker |first4=J. |date=1974 |title=Presence of PCB, DDE and DDT in human milk in the provinces of New Brunswick and Nova Scotia, Canada |url=https://doi.org/10.1007/BF01709117 |journal=Bulletin of Environmental Contamination and Toxicology |language=en |volume=12 |issue=3 |pages=258–267 |doi=10.1007/BF01709117 |pmid=4215516 |bibcode=1974BuECT..12..258M |issn=1432-0800}}</ref>

Because of its [[Lipophilicity|lipophilic]] properties, DDT can [[bioaccumulate]], especially in [[predatory birds]].<ref>{{cite book | title = Introduction to Ecotoxicology | publisher = Blackwell Science | year = 1999 | isbn = 978-0-632-03852-7 | page = 68 | url = https://books.google.com/books?id=X-ik73-vnXAC&pg=PA68 | first1 = Des W. | last1 = Connell | first2 = Paul | last2 = Lam | first3 = Bruce | last3 = Richardson | first4 = Rudolf | last4 = Wu | name-list-style = vanc | access-date = August 29, 2022 | archive-date = March 19, 2015 | archive-url = https://web.archive.org/web/20150319000333/http://books.google.com/books?id=X-ik73-vnXAC&pg=PA68 | url-status = live }}</ref> DDT is toxic to a wide range of living organisms, including marine animals such as [[crayfish]], [[daphnia|daphnids]], [[shrimp|sea shrimp]] and many species of [[fish]]. 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 stored mainly in body [[fat]]. DDT and DDE are 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.<ref name="PineRiver">{{cite journal | vauthors = Eskenazi B, Chevrier J, Rosas LG, Anderson HA, Bornman MS, Bouwman H, Chen A, Cohn BA, de Jager C, Henshel DS, Leipzig F, Leipzig JS, Lorenz EC, Snedeker SM, Stapleton D | title = The Pine River statement: human health consequences of DDT use | journal = Environmental Health Perspectives | volume = 117 | issue = 9 | pages = 1359–1367 | date = September 2009 | pmid = 19750098 | pmc = 2737010 | doi = 10.1289/ehp.11748 | bibcode = 2009EnvHP.117.1359E }}</ref> Estimated dietary intake has declined,<ref name="PineRiver"/> although FDA food tests commonly detect it.<ref>USDA, [[Pesticide Data Program]] Annual Summary Calendar Year''Pesticide Data Program Annual Summary Calendar Year 2005'', November 2006.</ref>

Despite being banned for many years, in 2018 research showed that DDT residues are still present in European soils and Spanish rivers.<ref name="Geissen">{{cite journal | vauthors = Silva V, Mol HG, Zomer P, Tienstra M, Ritsema CJ, Geissen V | title = Pesticide residues in European agricultural soils – A hidden reality unfolded | journal = The Science of the Total Environment | volume = 653 | pages = 1532–1545 | date = February 2019 | pmid = 30759587 | doi = 10.1016/j.scitotenv.2018.10.441 | bibcode = 2019ScTEn.653.1532S | doi-access = free }}</ref><ref name="PAN-E">{{cite web |last1=Roman |first1=Dolores |last2=Lysimachou |first2=Angeliki |last3=Balaguer |first3=Rodrigo |last4=Dimastrogiovanni |first4=Giorgio |last5=García |first5=Kistiñe |last6=González |first6=Erika |name-list-style=vanc |title=Ríos hormonados: Contamination of Spanish Rivers with Pesticides |url=https://www.pan-europe.info/resources/reports/2018/02/r%C3%ADos-hormonados-contamination-spanish-rivers-pesticides |website=Pesticide Action Network Europe |access-date=26 February 2019 |archive-date=February 27, 2019 |archive-url=https://web.archive.org/web/20190227060806/https://www.pan-europe.info/resources/reports/2018/02/r%C3%ADos-hormonados-contamination-spanish-rivers-pesticides |url-status=live }}</ref>

===Eggshell thinning{{anchor|Effects_on_wildlife_and_eggshell_thinning}}===
The chemical and its breakdown products DDE and DDD caused eggshell thinning and population declines in multiple North American and European [[bird of prey]] species.<ref name="ATSDRc5"/><ref>{{cite journal | vauthors = Vos JG, Dybing E, Greim HA, Ladefoged O, Lambré C, Tarazona JV, Brandt I, Vethaak AD | title = Health effects of endocrine-disrupting chemicals on wildlife, with special reference to the European situation | journal = Critical Reviews in Toxicology | volume = 30 | issue = 1 | pages = 71–133 | date = January 2000 | pmid = 10680769 | doi = 10.1080/10408440091159176 | s2cid = 11908661 }}</ref><ref name=Stokstad07/><ref name="Lundholm, 1997"/><ref name=Tubbs2016>{{cite journal |doi=10.1080/23273747.2016.1173766 |title=California condors and DDT: Examining the effects of endocrine disrupting chemicals in a critically endangered species |journal=Endocrine Disruptors |volume=4 |pages=e1173766 |year=2016 |last1=Tubbs |first1=Christopher W. | name-list-style = vanc |doi-access=free }}</ref><ref name="ibis">{{cite journal |doi=10.1046/j.1474-919X.2003.00132.x |title=California Condors and DDE: A re-evaluation |journal=Ibis |volume=145 |issue=1 |pages=136–151 |year=2002 |last1=Snyder |first1=Noel F. R. |last2=Meretsky |first2=Vicky J. | name-list-style = vanc }}</ref> Both laboratory experiments and field studies confirmed this effect.<ref>{{cite news | url = https://www.epa.gov/caddis-vol1/case-ddt-revisiting-impairment | title = The Case of DDT: Revisiting the Impairment | work = US Environmental Protection Agency (EPA) | access-date = August 5, 2021 | archive-date = August 5, 2021 | archive-url = https://web.archive.org/web/20210805060600/https://www.epa.gov/caddis-vol1/case-ddt-revisiting-impairment | url-status = live }}</ref> The effect was first conclusively proven at [[Bellow Island]] in [[Lake Michigan]] during [[University of Michigan]]-funded studies on [[American herring gull]]s in the mid-1960s.<ref name="mynorthscience">{{cite web |last1=Smith |first1=Jeff |title=The Science Behind Northport's Gull Island |url=https://mynorth.com/2017/05/the-science-behind-northports-gull-island/ |website=MyNorth.com |access-date=8 September 2020 |date=9 May 2017 |archive-date=May 19, 2021 |archive-url=https://web.archive.org/web/20210519235311/https://mynorth.com/2017/05/the-science-behind-northports-gull-island/ |url-status=live }}</ref> DDE-related eggshell thinning is considered a major reason for the decline of the [[bald eagle]],<ref name=Stokstad07/> [[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. {{Federal Register|73|9407}}</ref> [[peregrine falcon]] and [[osprey]].<ref name="ATSDRc5" /> However, birds vary in their sensitivity to these chemicals, with [[birds of prey]], [[waterfowl]] and [[passerine|song birds]] being more susceptible than [[chicken]]s and [[Galliformes|related species]].<ref name="ATSDRc5"/><ref name="EHC83" />   Even in 2010, [[California condor]]s that feed on [[sea lion]]s at [[Big Sur]] that in turn feed in the Palos Verdes Shelf area of the [[Montrose Chemical Corporation of California|Montrose Chemical]] [[Superfund]] site exhibited continued thin-shell problems,<ref>{{cite news | last = Moir | first = John | name-list-style = vanc | url = https://www.nytimes.com/2010/11/16/science/16condors.html | title = New Hurdle for California Condors May Be DDT From Years Ago | work = The New York Times | date = November 15, 2010 | access-date = February 7, 2017 | archive-date = September 21, 2017 | archive-url = https://web.archive.org/web/20170921194609/http://www.nytimes.com/2010/11/16/science/16condors.html | url-status = live }}</ref><ref>{{cite journal |vauthors=Kurle CM, Bakker VJ, Copeland H, Burnett J, Jones Scherbinski J, Brandt J, Finkelstein ME |title=Terrestrial Scavenging of Marine Mammals: Cross-Ecosystem Contaminant Transfer and Potential Risks to Endangered California Condors (Gymnogyps californianus) |journal=Environmental Science & Technology |volume=50 |issue=17 |pages=9114–9123 |year=2016 |pmid=27434394 |doi=10.1021/acs.est.6b01990 |bibcode=2016EnST...50.9114K |s2cid=206559840 |url=http://www.escholarship.org/uc/item/1646t91t |access-date=June 13, 2019 |archive-date=June 22, 2020 |archive-url=https://web.archive.org/web/20200622174112/https://escholarship.org/uc/item/1646t91t |url-status=live }}</ref>  though DDT's role in the decline of the [[California condor]] is disputed.<ref name="ibis"/><ref name=Tubbs2016/>

The biological thinning mechanism is not entirely understood, but DDE appears to be more potent than DDT,<ref name="ATSDRc5"/> and strong evidence indicates that ''p'',''p{{'}}''-DDE inhibits [[calcium ATPase]] in the [[Biological membrane|membrane]] of the shell gland and reduces the transport of [[calcium carbonate]] from [[blood]] into the eggshell gland. This results in a dose-dependent thickness reduction.<ref name="ATSDRc5"/><ref>{{cite book | vauthors = Walker CH, Sibly RM, Hopkin SP, Peakall DB | title = Principles of ecotoxicology | publisher = CRC/Taylor & Francis | location = Boca Raton, FL | isbn = 978-0-8493-3635-5 | year = 2006 | edition = 3rd | url = https://books.google.com/books?id=WxfSBQAAQBAJ&pg=PA300 | pages = 300 ff | access-date = August 29, 2022 | archive-date = July 31, 2020 | archive-url = https://web.archive.org/web/20200731135732/https://books.google.com/books?id=WxfSBQAAQBAJ&pg=PA300 | url-status = live }}</ref><ref name="Guillette, 2006">{{cite web |last=Guillette |first=Louis J. |name-list-style=vanc |year=2006 |url=http://www.ehponline.org/members/2005/8045/8045.pdf |title=Endocrine Disrupting Contaminants |access-date=February 2, 2007 |archive-url=https://web.archive.org/web/20090325085455/http://www.ehponline.org/members/2005/8045/8045.pdf |archive-date=March 25, 2009 |url-status=dead |df=mdy }}</ref><ref name="Lundholm, 1997">{{cite journal | vauthors = Lundholm CD | title = DDE-induced eggshell thinning in birds: effects of ''p'',''p{{'}}''-DDE on the calcium and prostaglandin metabolism of the eggshell gland | journal = Comparative Biochemistry and Physiology C | volume = 118 | issue = 2 | pages = 113–128 | date = October 1997 | pmid = 9490182 | doi = 10.1016/S0742-8413(97)00105-9 }}</ref> Other evidence indicates that o,p'-DDT disrupts female reproductive tract development, later impairing eggshell quality.<ref>{{cite journal | vauthors = 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 =Environmental Toxicology and Chemistry| volume = 25 | issue = 10 | pages = 2787–2793 | date = October 2006 | pmid = 17022422 | doi = 10.1897/05-619R.1 | s2cid = 9298213 }}</ref> Multiple mechanisms may be at work, or different mechanisms may operate in different species.<ref name="ATSDRc5"/>