Editing Arsenic (section)

=== Occurrence in drinking water ===
{{Main|Arsenic contamination of groundwater}}

Extensive arsenic contamination of groundwater has led to widespread [[arsenic poisoning]] in [[Water supply and sanitation in Bangladesh|Bangladesh]]<ref>{{cite book |first = Andrew |last = Meharg |year= 2005 |title = Venomous Earth – How arsenic caused the world's worst mass poisoning |isbn = 978-1-4039-4499-3 |publisher = Macmillan Science |url-access = registration|url = https://archive.org/details/venomousearthhow00meha}}</ref> and neighboring countries.<!--As of this writing,{{when|date=June 2012}}{{citation needed|date=June 2012}} 42&nbsp;major incidents around the world have been reported on groundwater arsenic contamination.--> It is estimated that approximately 57&nbsp;million people in the Bengal basin are drinking [[groundwater]] with arsenic concentrations elevated above the [[World Health Organization]]'s standard of 10&nbsp;[[Concentration#"Parts-per" notation|parts per billion]] (ppb).<ref>{{cite book |url = https://books.google.com/books?id=hMA70VU36qUC&pg=PA317 |page = 317 |title = Arsenic: Environmental Chemistry, Health Threats and Waste Treatment |isbn = 978-0-470-02758-5 |last1 = Henke |first1 = Kevin R. |date = 28 April 2009|publisher = John Wiley & Sons }}</ref> However, a study of cancer rates in [[Taiwan]]<ref>{{cite journal |doi=10.1289/ehp.8704 |journal=Environ. Health Perspect. |volume=114 |issue=7 |pages=1077–1082 |date=2006 |pmid=16835062 |pmc=1513326 |last1=Lamm |first1=S. H. |last2=Engel |first2=A. |last3=Penn |first3=C. A. |last4=Chen |first4=R. |last5=Feinleib |first5=M. |title=Arsenic cancer risk confounder in southwest Taiwan dataset |bibcode=2006EnvHP.114.1077L }}</ref> suggested that significant increases in cancer mortality appear only at levels above 150&nbsp;ppb. The arsenic in the groundwater is of natural origin, and is released from the sediment into the groundwater, caused by the [[Dead zone (ecology)|anoxic conditions]] of the subsurface. This groundwater was used after local and western [[Non-governmental organization|NGOs]] and the Bangladeshi government undertook a massive shallow tube [[Water well|well]] drinking-water program in the late twentieth century. This program was designed to prevent drinking of bacteria-contaminated surface waters, but failed to test for arsenic in the groundwater. Many other countries and districts in Southeast Asia, such as [[Vietnam]] and [[Cambodia]], have geological environments that produce groundwater with a high arsenic content. [[Arsenic poisoning#Arsenicosis: chronic arsenic poisoning from drinking water|Arsenicosis]] was reported in [[Nakhon Si Thammarat]], Thailand, in 1987, and the [[Chao Phraya River]] probably contains high levels of naturally occurring dissolved arsenic without being a public health problem because much of the public uses [[bottled water]].<ref>{{cite journal |first = Andrew |last = Kohnhorst |year=2005 |title=Arsenic in groundwater in selected countries in south and southeast Asia: A review |journal=J Tropical Medicine and Parasitology |volume=28 |page=73  |url=http://antispam.kmutt.ac.th/index.php/JTMP/article/view/14749 |archive-url=https://web.archive.org/web/20140110085919/http://antispam.kmutt.ac.th/index.php/JTMP/article/view/14749 |url-status = dead |archive-date=2014-01-10}}</ref> In Pakistan, more than 60&nbsp;million people are exposed to arsenic polluted drinking water indicated by a 2017 report in [[Science (journal)|''Science'']]. Podgorski's team investigated more than 1200&nbsp;samples and more than 66% exceeded the [[World Health Organization|WHO]] contamination limits of 10 micrograms per liter.<ref>{{cite journal |title=Arsenic in drinking water threatens up to 60&nbsp;million in Pakistan |date=2017-08-23 |journal=[[Science (journal)|Science]] |publisher=[[American Association for the Advancement of Science|AAAS]] |url=https://www.science.org/content/article/arsenic-drinking-water-threatens-60-million-pakistan |access-date=2017-09-11 |language=en }}</ref>

Since the 1980s, residents of the Ba Men region of Inner Mongolia, China have been chronically exposed to arsenic through drinking water from contaminated wells.<ref name="Well Water Arsenic Exposure, Arsenic Induced Skin-Lesions and Self-Reported Morbidity in Inner Mongolia">{{cite journal |last1=Xia |first1=Yajuan |last2=Wade |first2=Timothy |last3=Wu |first3=Kegong |last4=Li |first4=Yanhong |last5=Ning |first5=Zhixiong |last6=Le |first6=X. Chris |last7=He |first7=Xingzhou |last8=Chen |first8=Binfei |last9=Feng |first9=Yong |last10=Mumford |first10=Judy |display-authors=6 |title=Well Water Arsenic Exposure, Arsenic Induced Skin-Lesions and Self-Reported Morbidity in Inner Mongolia |journal=International Journal of Environmental Research and Public Health |date=9 March 2009 |volume=6 |issue=3 |pages=1010–1025 |doi=10.3390/ijerph6031010 |pmid=19440430 |pmc=2672384 |doi-access=free }}</ref> A 2009 research study observed an elevated presence of skin lesions among residents with well water arsenic concentrations between 5 and 10&nbsp;μg/L, suggesting that arsenic-induced toxicity may occur at relatively low concentrations with chronic exposure.<ref name="Well Water Arsenic Exposure, Arsenic Induced Skin-Lesions and Self-Reported Morbidity in Inner Mongolia" /> Overall, 20 of China's 34 provinces have high arsenic concentrations in the groundwater supply, potentially exposing 19&nbsp;million people to hazardous drinking water.<ref name="Lall">{{Cite journal|last1=Lall|first1=Upmanu|last2=Josset|first2=Laureline|last3=Russo|first3=Tess|date=2020-10-17|title=A Snapshot of the World's Groundwater Challenges|journal=Annual Review of Environment and Resources|language=en|volume=45|issue=1|pages=171–194|doi=10.1146/annurev-environ-102017-025800|doi-access=free }}</ref>

A study by [[IIT Kharagpur]] found high levels of Arsenic in groundwater of 20% of India's land, exposing more than 250&nbsp;million people. States such as [[Punjab]], Bihar, [[West Bengal]], Assam, [[Haryana]], Uttar Pradesh, and [[Gujarat]] have highest land area exposed to arsenic.<ref>{{cite news |title=IIT Kharagpur Study Finds 20% of India Has High Arsenic Levels in Groundwater |url=https://science.thewire.in/health/iit-kharagpurs-ai-study-finds-20-of-india-has-toxic-levels-of-arsenic-in-groundwater/ |access-date=2023-05-23 |work=[[The Wire (India)|The Wire]] |agency=PTI |date=2021-02-11}}</ref>

In the United States, arsenic is most commonly found in the ground waters of the southwest.<ref name="test">{{cite web|url = http://h2oc.com/pdfs/Occurrence.pdf|title = Arsenic in Drinking Water: 3. Occurrence in U.S. Waters|access-date = 2010-05-15|url-status = dead|archive-url = https://web.archive.org/web/20100107171246/http://h2oc.com/pdfs/Occurrence.pdf|archive-date = 7 January 2010}}</ref> Parts of [[New England]], [[Michigan]], [[Wisconsin]], [[Minnesota]] and the Dakotas are also known to have significant concentrations of arsenic in ground water.<ref>{{cite journal |doi=10.1111/j.1745-6584.2000.tb00251.x |title=Arsenic in Ground Water of the United States: Occurrence and Geochemistry |date=2000 |last1=Welch |first1=Alan H. |last2=Westjohn |first2=D. B. |last3=Helsel |first3=Dennis R. |last4=Wanty |first4=Richard B. |journal=Ground Water |volume=38 |issue=4 |pages=589–604|bibcode=2000GrWat..38..589W |s2cid=129409319 }}</ref> Increased levels of skin cancer have been associated with arsenic exposure in Wisconsin, even at levels below the 10&nbsp;ppb drinking water standard.<ref>{{cite journal |title=Association of arsenic-contaminated drinking-water with prevalence of skin cancer in Wisconsin's Fox River Valley |journal=J. Health Popul Nutr |volume=24 |issue=2 |pages=206–213 |date=2006 |pmid=17195561|last1=Knobeloch |first1=L. M. |last2=Zierold |first2=K. M. |last3=Anderson |first3=H. A.|hdl=1807/50099 |hdl-access=free }}</ref> According to a recent film funded by the US [[Superfund]], millions of private wells have unknown arsenic levels, and in some areas of the US, more than 20% of the wells may contain levels that exceed established limits.<ref>{{cite web |url=http://www.dartmouth.edu/~toxmetal/InSmallDoses/ |title=In Small Doses:Arsenic|work=The Dartmouth Toxic Metals Superfund Research Program. Dartmouth College}}</ref>

Low-level exposure to arsenic at concentrations of 100&nbsp;ppb (i.e., above the 10&nbsp;ppb drinking water standard) compromises the initial immune response to [[Influenza A virus subtype H1N1|H1N1 or swine flu]] infection according to NIEHS-supported scientists. The study, conducted in laboratory mice, suggests that people exposed to arsenic in their drinking water may be at increased risk for more serious illness or death from the virus.<ref>{{cite journal|last1=Courtney|first1=D.|date=2009|title=Low Dose Arsenic Compromises the Immune Response to Influenza A Infection in vivo|pages=1441–1447|pmid=19750111|pmc=2737023|issue=9|doi=10.1289/ehp.0900911|volume=117|last2=Ely|first2=Kenneth H.|last3=Enelow|first3=Richard I.|last4=Hamilton|first4=Joshua W.|journal=Environmental Health Perspectives|bibcode=2009EnvHP.117.1441K }}</ref>

Some Canadians are drinking water that contains inorganic arsenic. Private-dug–well waters are most at risk for containing inorganic arsenic. Preliminary well water analysis typically does not test for arsenic. Researchers at the Geological Survey of Canada have modeled relative variation in natural arsenic hazard potential for the province of New Brunswick. This study has important implications for potable water and health concerns relating to inorganic arsenic.<ref name="GSC-2009">{{cite web|last1=Klassen |first1=R. A. |last2=Douma |first2=S. L. |last3=Ford |first3=A. |last4=Rencz |first4=A. |last5=Grunsky |first5=E. |title=Geoscience modeling of relative variation in natural arsenic hazard in potential in New Brunswick |url=http://geogratis.cgdi.gc.ca/eodata/download/part6/ess_pubs/247/247834/cr_2009_07_gsc.pdf |date=2009 |publisher=[[Geological Survey of Canada]] |access-date=2012-10-14 |url-status = dead|archive-url=https://web.archive.org/web/20130502043721/http://geogratis.cgdi.gc.ca/eodata/download/part6/ess_pubs/247/247834/cr_2009_07_gsc.pdf |archive-date=2 May 2013 }}</ref>

Epidemiological evidence from Chile shows a dose-dependent connection between chronic arsenic exposure and various forms of cancer, in particular when other risk factors, such as cigarette smoking, are present. These effects have been demonstrated at contaminations less than 50&nbsp;ppb.<ref>{{cite journal |title=Arsenic exposure and its impact on health in Chile |journal=J Health Popul Nutr |volume=24 |issue=2 |pages=164–175 |date=2006 |pmid=17195557|last1=Ferreccio |first1=C. |last2=Sancha |first2=A. M.|hdl=1807/50095 |hdl-access=free }}</ref> Arsenic is itself a constituent of [[tobacco smoke]].<ref name="TalhoutSchulz2011">{{cite journal|last1=Talhout|first1=Reinskje|last2=Schulz|first2=Thomas|last3=Florek|first3=Ewa|last4=Van Benthem|first4=Jan|last5=Wester|first5=Piet|last6=Opperhuizen|first6=Antoon|title=Hazardous Compounds in Tobacco Smoke|journal=International Journal of Environmental Research and Public Health|volume=8|issue=12|year=2011|pages=613–628|doi=10.3390/ijerph8020613|pmid=21556207|pmc=3084482|doi-access=free}}</ref>

Analyzing multiple epidemiological studies on inorganic arsenic exposure suggests a small but measurable increase in risk for bladder cancer at 10&nbsp;ppb.<ref>{{cite journal |last1=Chu|first1= H. A. |last2 = Crawford-Brown|first2= D. J. |title=Inorganic arsenic in drinking water and bladder cancer: a meta-analysis for dose-response assessment |journal=Int. J. Environ. Res. Public Health |volume=3 |issue=4 |pages=316–322 |date=2006 |pmid=17159272 |doi=10.3390/ijerph2006030039|doi-access=free |pmc=3732405 }}</ref> According to Peter Ravenscroft of the Department of Geography at the University of Cambridge,<ref>{{cite news |url = https://www.usatoday.com/news/world/2007-08-30-553404631_x.htm|title = Arsenic in drinking water seen as threat – USATODAY.com|access-date = 2008-01-01 |work=USA Today|date=30 August 2007}}</ref> roughly 80&nbsp;million people worldwide consume between 10 and 50&nbsp;ppb arsenic in their drinking water. If they all consumed exactly 10&nbsp;ppb arsenic in their drinking water, the previously cited multiple epidemiological study analysis would predict an additional 2,000 cases of bladder cancer alone. This represents a clear underestimate of the overall impact, since it does not include lung or skin cancer, and explicitly underestimates the exposure. Those exposed to levels of arsenic above the current WHO standard should weigh the costs and benefits of arsenic remediation.

<!-- RECENTISM, local university news: Several arsenic kits are available in the market which uses toxic mercury bromide, also required expensive machinery to read the outputs. A new test instrument called whole-cell arsenic bio-sensor, a cheap and non-toxic one, has been designed at the University of Edinburgh.<ref>[http://www.cam.ac.uk/research/news/new-test-to-detect-arsenic-contamination-in-drinking-water/ New test to detect arsenic contamination in drinking water – Research – University of Cambridge]. Cam.ac.uk (2012-06-01). Retrieved 2012-06-20.</ref> -->
Early (1973) evaluations of the processes for removing dissolved arsenic from drinking water demonstrated the efficacy of co-precipitation with either iron or aluminium oxides. In particular, iron as a coagulant was found to remove arsenic with an efficacy exceeding 90%.<ref>{{cite journal|title=Removal of Arsenic (V) from Water by Adsorption on Aluminum and Ferric Hydroxides|journal=J. Am. Water Works Assoc.| volume=65| issue=8|pages=548–552|date=1973|last1 = Gulledge| first1 = John H.| last2 = O'Connor|first2 = John T.|doi=10.1002/j.1551-8833.1973.tb01893.x|bibcode=1973JAWWA..65h.548G }}</ref><ref>{{cite news| url = http://www.h2oc.com/pdfs/Removal.pdf| title = Arsenic in Drinking Water: 4. Removal Methods| last1 = O'Connor| first1 = J. T.| last2 = O'Connor| first2 = T. L.|url-status = dead| archive-url = https://web.archive.org/web/20100107182531/http://h2oc.com/pdfs/Removal.pdf| archive-date = 7 January 2010}}</ref> Several adsorptive media systems have been approved for use at point-of-service in a study funded by the [[United States Environmental Protection Agency]] (US EPA) and the [[National Science Foundation]] (NSF). A team of European and Indian scientists and engineers have set up six arsenic treatment plants in [[West Bengal]] based on in-situ remediation method (SAR Technology). This technology does not use any chemicals and arsenic is left in an insoluble form (+5 state) in the subterranean zone by recharging aerated water into the aquifer and developing an oxidation zone that supports arsenic oxidizing micro-organisms. This process does not produce any waste stream or sludge and is relatively cheap.<ref>{{cite web|url = http://www.insituarsenic.org|title = In situ arsenic treatment|work=insituarsenic.org|access-date = 2010-05-13 }}</ref>

Another effective and inexpensive method to avoid arsenic contamination is to sink wells 500&nbsp;feet or deeper to reach purer waters. A recent 2011 study funded by the US National Institute of Environmental Health Sciences' Superfund Research Program shows that deep sediments can remove arsenic and take it out of circulation. In this process, called ''adsorption'', arsenic sticks to the surfaces of deep sediment particles and is naturally removed from the ground water.<ref>{{cite journal |doi=10.1038/ngeo1283 |title=Arsenic migration to deep groundwater in Bangladesh influenced by adsorption and water demand |date=2011|last1=Radloff|first1=K.A. |last2=Zheng |first2=Y. |last3=Michael |first3=H.A. |last4=Stute |first4=M. |last5=Bostick |first5=B.C. |last6=Mihajlov |first6=I. |last7=Bounds|first7=M. |last8=Huq|first8=M. R. |last9=Choudhury |first9=I.|first10=M. |last10=Rahman|first11=P. |last11=Schlosser |first12=K. |last12=Ahmed |first13=A. |last13=van Geen |display-authors=6 |journal=Nature Geoscience |volume=4 |issue=11 |pages=793–798 |pmid=22308168 |pmc=3269239 |bibcode = 2011NatGe...4..793R}}</ref>

Magnetic separations of arsenic at very low magnetic field [[gradient]]s with high-surface-area and [[monodisperse]] [[magnetite]] (Fe<sub>3</sub>O<sub>4</sub>) nanocrystals have been demonstrated in point-of-use water purification. Using the high specific surface area of Fe<sub>3</sub>O<sub>4</sub> nanocrystals, the mass of waste associated with arsenic removal from water has been dramatically reduced.<ref>{{cite journal|last1 = Yavuz|first1 = Cafer T.|title = Low-field magnetic separation of monodisperse Fe<sub>3</sub>O<sub>4</sub> nanocrystals |journal = Science |year = 2005 |doi = 10.1126/science.1131475 |volume = 314 |issue = 580 1|pages = 964–967 |pmid = 17095696|last2 = Mayo|first2 = J.T. |last3 = Yu |first3 = W.W. |last4 = Prakash |first4 = A. |last5 = Falkner |first5 = J. C.|last6 = Yean|first6 = S.|last7 = Cong | first7 = L. |last8 = Shipley |first8 = H.J. |last9 = Kan |first9 = A. |first10=M. |last10=Tomson |first11=D. |last11=Natelson |first12=V.L. |last12=Colvin |display-authors=6 |s2cid = 23522459}}</ref>

Epidemiological studies have suggested a correlation between chronic consumption of drinking water contaminated with arsenic and the incidence of all leading causes of mortality.<ref>{{cite journal |pmc = 1797014 |last1 = Meliker |first1 = J. R. |last2 = Wahl |first2 = R. L. |last3 = Cameron |first3 = L. L. |last4 = Nriagu |first4 = J. O. |title = Arsenic in drinking water and cerebrovascular disease, diabetes mellitus, and kidney disease in Michigan: A standardized mortality ratio analysis |volume = 6 |page = 4 |doi = 10.1186/1476-069X-6-4 |journal = Environmental Health |year = 2007 |issue = 1 |pmid = 17274811 |bibcode = 2007EnvHe...6....4M |doi-access = free }}</ref> The literature indicates that arsenic exposure is causative in the pathogenesis of diabetes.<ref>{{cite journal |doi=10.1289/ehp.00108847 |title=Long-term arsenic exposure and incidence of non-insulin-dependent diabetes mellitus: A cohort study in arseniasis-hyperendemic villages in Taiwan |year=2000 |last1=Tseng |first1=Chin-Hsiao |last2=Tai |first2=Tong-Yuan |last3=Chong |first3=Choon-Khim |last4=Tseng |first4=Ching-Ping |last5=Lai |first5=Mei-Shu |last6=Lin |first6=Boniface J. |last7=Chiou |first7=Hung-Yi |last8=Hsueh |first8=Yu-Mei |last9=Hsu |first9=Kuang-Hung |last10=Chen |first10=C. J. |display-authors=6 |journal=Environmental Health Perspectives |volume=108 |issue=9 |pages=847–851 |pmid=11017889 |pmc=2556925|bibcode=2000EnvHP.108..847T }}</ref>

Chaff-based filters have recently been shown to reduce the arsenic content of water to 3&nbsp;μg/L. This may find applications in areas where the potable water is extracted from underground [[aquifer]]s.<ref>{{cite news |url=http://mno.hu/gazdasag/szenzacios-magyar-talalmany-1068315 |title=Newspaper article |archive-url=https://web.archive.org/web/20120417212726/http://mno.hu/gazdasag/szenzacios-magyar-talalmany-1068315 |archive-date=17 April 2012 |language=Hungarian |publisher=[[Magyar Nemzet]] |date=15 April 2012 }}</ref>

==== San Pedro de Atacama ====
{{see also|Atacama people|Chinchorro mummies}}
[[File:Miscanti Lagoon near San Pedro de Atacama Chile Luca Galuzzi 2006.jpg|thumb|'''Miscanti Lagoon near San Pedro de Atacama Chile Luca Galuzzi 2006''']]
For several centuries, the people of [[San Pedro de Atacama]] in Chile have been drinking water that is contaminated with arsenic, and some evidence suggests they have developed some immunity.<ref>{{cite journal |last1=Goering |first1=P. |last2=Aposhian |first2=H.V. |last3=Mass |first3=M.J. |last4=Cebrián |first4=M. |last5=Beck |first5=B.D. |last6=Waalkes |first6=M.P. |title=The enigma of arsenic carcinogenesis: role of metabolism |journal=Toxicological Sciences |date=May 1999 |volume=49 |issue=1 |pages=5–14 |doi=10.1093/toxsci/49.1.5 |pmid=10367337 }}</ref><ref>{{cite journal |date=1996 |last1=Hopenhayn-Rich |first1=C. |last2=Biggs |first2=M. L. |last3=Smith |first3=Allan H. |last4=Kalman |first4=D. A. |last5=Moore |first5=Lee E. |title=Methylation study of a population environmentally exposed to arsenic in drinking water |journal=Environmental Health Perspectives |volume=104 |issue=6 |pages=620–628 |doi=10.1289/ehp.96104620 |pmid=8793350 |pmc=1469390 |bibcode=1996EnvHP.104..620H }}</ref><ref>{{cite journal |last1=Smith |first1=A.H. |last2=Arroyo |first2=A.P. |last3=Mazumder |first3=D.N. |last4=Kosnett |first4=M.J. |last5=Hernandez |first5=A L |last6=Beeris |first6=M. |last7=Smith |first7=M.M. |last8=Moore |first8=L.E. |display-authors=6 |title=Arsenic-induced skin lesions among Atacameño people in Northern Chile despite good nutrition and centuries of exposure. |journal=Environmental Health Perspectives |date=July 2000 |volume=108 |issue=7 |pages=617–620 |doi=10.1289/ehp.00108617 |pmid=10903614 |pmc=1638201 |bibcode=2000EnvHP.108..617S }}</ref> Genetic studies indicate that certain populations in this region have undergone natural selection for gene variants that enhance arsenic metabolism and detoxification. This adaptation is considered one of the few documented cases of human evolution in response to chronic environmental arsenic exposure.<ref>{{Cite journal |last1=Schlebusch |first1=Carina M. |last2=Gattepaille |first2=Lucie M. |last3=Engström |first3=Karin |last4=Vahter |first4=Marie |last5=Jakobsson |first5=Mattias |last6=Broberg |first6=Karin |date=2015-06-01 |title=Human Adaptation to Arsenic-Rich Environments |url=https://academic.oup.com/mbe/article/32/6/1544/1074042 |journal=Molecular Biology and Evolution |volume=32 |issue=6 |pages=1544–1555 |doi=10.1093/molbev/msv046 |pmid=25739736 |issn=0737-4038|doi-access=free }}</ref>

==== Hazard maps for contaminated groundwater ====
Around one-third of the world's population drinks water from groundwater resources. Of this, about 10 percent, approximately 300&nbsp;million people, obtains water from groundwater resources that are contaminated with unhealthy levels of arsenic or fluoride.<ref>Eawag (2015) Geogenic Contamination Handbook – Addressing Arsenic and Fluoride in Drinking Water. C.A. Johnson, A. Bretzler (Eds.), Swiss Federal Institute of Aquatic Science and Technology (Eawag), Duebendorf, Switzerland. (download: www.eawag.ch/en/research/humanwelfare/drinkingwater/wrq/geogenic-contamination-handbook/)</ref> These trace elements derive mainly from minerals and ions in the ground.<ref>{{cite journal | last1=Amini |first1=M.|last2=Abbaspour |first2=K.C. |last3=Berg |first3=M. |last4=Winkel |first4=L. |last5=Hug |first5=S.J. |last6=Hoehn |first6=E. |last7= Yang |first7=H. |last8=Johnson |first8=C.A. |display-authors=6 | year = 2008 | title = Statistical modeling of global geogenic arsenic contamination in groundwater | journal = Environmental Science and Technology | volume = 42 | issue = 10| pages = 3669–3675 | doi = 10.1021/es702859e | pmid = 18546706 | bibcode = 2008EnST...42.3669A | doi-access = free }}</ref><ref>{{cite journal |last1=Winkel |first1=Lenny |last2=Berg |first2=Michael |last3=Amini |first3=Manouchehr |last4=Hug |first4=Stephan J. |last5=Annette Johnson |first5=C. |title=Predicting groundwater arsenic contamination in Southeast Asia from surface parameters |journal=Nature Geoscience |date=August 2008 |volume=1 |issue=8 |pages=536–542 |doi=10.1038/ngeo254 |bibcode=2008NatGe...1..536W |url=https://www.dora.lib4ri.ch/eawag/islandora/object/eawag%3A5777 }}</ref>