Final Technical Support Document on the Public Health Goal for Perchlorate in Drinking Water

Feb 27, 2015

The Office of Environmental Health Hazard Assessment (OEHHA) of the California Environmental Protection Agency announces the publication of the updated Public Health Goal (PHG) for perchlorate in drinking water and the availability of the final technical support document for this PHG.

The updated PHG is one part-per-billion (1 ppb) based on the inhibition of iodide uptake into the thyroid gland and the consequent disruption of thyroid hormone production. The update considers recent toxicological and epidemiological literature providing new information on exposures to and possible effects of perchlorate, focuses on infants as a susceptible population, and, pursuant to California Health and Safety Code Section 116365.2, incorporates updated drinking water ingestion rates for infants. These considerations have resulted in a decrease of the perchlorate PHG from 6 ppb to 1 ppb.

The PHG technical support document provides information on the health effects of perchlorate in drinking water. The PHG is a level of drinking water contaminant at which adverse health effects are not expected to occur. The California Safe Drinking Water Act of 1996¹ requires OEHHA to develop PHGs based exclusively on public health considerations². PHGs published by OEHHA are considered by the State Water Resources Control Board in setting drinking water standards (Maximum Contaminant Levels, or MCLs).³

Draft documents for perchlorate have gone through a public workshop, two public comment periods, and external scientific peer review. The first public-review draft was released on January 7, 2011 and a public workshop was held on February 23, 2011. During the first public comment period, an external scientific peer review of the draft PHG document was requested. The peer review was conducted pursuant to Health and Safety Code Section 116365(c)(3)(D). The revised draft document, as well as responses to scientific peer review comments, were released for public review on December 7, 2012. OEHHA has evaluated all the comments received and revised the document as appropriate.

If you would like to receive further information on this announcement or have questions, please contact the PHG program at PHG.Program@oehha.ca.gov or (916) 324-7572.

¹Codified at Health and Safety Code, section 116270 et. seq.

²Health and Safety Code section 116365(c)

³Health and Safety Code section 116365(a) and (b)