Arsenic organic arsenic http://www.atsdr.cdc.gov/toxfaqs/TF.asp?id=19&tid=3 http://www.atsdr.cdc.gov/toxfaqs/TF.asp?id=19&tid=3 “Division of Toxicology and Environmental Medicine ToxFAQs” is found naturally http://www.atsdr.cdc.gov/toxfaqs/TF.asp?id=19&tid=3