title: Development of a health-protective drinking water level for perchlorate.
abstract: We evaluated animal and human toxicity data for perchlorate and identified reduction of thyroidal iodide uptake as the critical end point in the development of a health-protective drinking water level [also known as the public health goal (PHG)] for the chemical. This work was performed under the drinking water program of the Office of Environmental Health Hazard Assessment of the California Environmental Protection Agency. For dose-response characterization, we applied benchmark-dose modeling to human data and determined a point of departure (the 95% lower confidence limit for 5% inhibition of iodide uptake) of 0.0037 mg/kg/day. A PHG of 6 ppb was calculated by using an uncertainty factor of 10, a relative source contribution of 60%, and exposure assumptions specific to pregnant women. The California Department of Health Services will use the PHG, together with other considerations such as economic impact and engineering feasibility, to develop a California maximum contaminant level for perchlorate. We consider the PHG to be adequately protective of sensitive subpopulations, including pregnant women, their fetuses, infants, and people with hypothyroidism.
authors.affiliation: Pesticide and Environmental Toxicology Branch, Office of Environmental Health Hazard Assessment, California Environmental Protection Agency, Oakland, California 94612, USA. dting@oehha.ca.gov
authors.forename: David
authors.initials: D
authors.lastname: Ting
authors.forename: Robert A
authors.initials: RA
authors.lastname: Howd
authors.forename: Anna M
authors.initials: AM
authors.lastname: Fan
authors.forename: George V
authors.initials: GV
authors.lastname: Alexeeff
mesh_terms: D000818:Animals; D002140:California; D004305:Dose-Response Relationship, Drug; D006077:Government Agencies; D017408:Guidelines as Topic; D006801:Humans; D010472:Perchlorates / Q000032:analysis* / Q000493:pharmacokinetics / Q000633:toxicity; D051381:Rats; D014881:Water Supply
chemical_list: D010472:Perchlorates