Editing Arsenic (section)

==== 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>