Initiation of Risk Assessments for Chemicals in Drinking Water (2006)

A. Requirements

The Calderon-Sher California Safe Drinking Water Act of 1996 requires the Office of Environmental Health Hazard Assessment (OEHHA) to post notices on its Web site of water contaminants for which it is initiating work, pursuant to development of a public health goal (PHG) for the chemical in drinking water. The law also describes the intent and general context of the PHGs. PHGs are concentrations of chemicals in drinking water that are not anticipated to produce adverse health effects following long-term exposures. These goals are non-regulatory in nature but are to be used as the health basis to update the state's primary drinking water standards (maximum contaminant levels, or MCLs) established by the California Department of Health Services (DHS) for chemicals subject to regulation.

The act requires PHGs to be developed for the approximately 87 chemicals for which state MCLs are presently available, and review and update of the risk assessments at least every five years. Other chemicals may be added to the list by legislative or interdepartmental request.

Opportunities for public comment and peer review are provided.

B. Implementation
OEHHA has published 80 PHGs as of March 2006, although one of these evaluations, that for total chromium, has been rescinded. Two MCLs, for gross alpha and gross beta radionuclides, represent screening levels for contaminants rather than specific regulatory standards; for these, OEHHA has provided risk assessments and guidance memoranda. The technical support documents for these chemicals are posted on the OEHHA Web site.

PHGs for all the other chemicals that have state MCLs are currently in preparation. Drafts for public comment on five of these chemicals are posted on the OEHHA Web site. PHGs for the remaining chemicals with existing MCLs should be released for public review this year. A 45-day public comment period will be provided after posting, followed by a public workshop. The overall process includes an opportunity for scientific peer review arranged through the University of California, allotting time for revisions, further public comment, and preparing responses to comments.

The PHG re-evaluation has been completed for thallium, inorganic mercury, lindane, and 1,2-dichloroethane. OEHHA concluded that no new information was available on these chemicals that would require significant changes to the PHG document. Memoranda to this effect are available here.

The re-reviews of several other chemicals that were announced in 2004 or 2005 are in progress.

Evaluation is now being initiated for several other chemicals for which PHGs were developed earlier, which will now be re-reviewed as part of the ongoing PHG update process.

Comments are requested on each of these chemicals.

C. PHGs to be released for public review:
Draft documents for the following chemicals are nearing completion, and are planned for release for public review and comment:

  • Chlorite
  • 2,4-Dichlorophenoxyacetic acid (2,4-D)
  • Molinate
  • Selenium
  • Styrene
  • Trihalomethanes

Comments were received during and after the first posting for public comment on the following chemicals, and the PHG documents are being prepared for a second posting for public comment:

  • Cadmium
  • Copper
  • Dioxin
  • Glyphosate
  • Nitrosodimethylamine
  • Polychlorinated biphenyls (PCBs)

D. Initiation of risk assessments
Risk assessment is being initiated for the following list of chemicals:

  • Alachlor
  • Atrazine and simazine
  • Chlordane
  • 1,3-Dichloropropene (Telone)
  • Fluoride
  • Lead
  • Nitrate/nitrite

These risk assessments are updates of assessments prepared in the first years of our program. The chemicals have been prioritized on the basis of availability of new data and significance as drinking water contaminants. A brief description of the chemicals is provided below. This announcement solicits the submission of pertinent information on the contaminants that could assist our office in preparing or updating the risk assessment and deriving a PHG.

Information submitted to OEHHA in response to this request should not be proprietary in nature, because all information submitted is a matter of public record. Information should be submitted by August 31, 2006 to:

PHG Project
Pesticide and Environmental Toxicology Section
Office of Environmental Health Hazard Assessment
P.O. Box 4010
Sacramento, California 95812-4010

All data submitted will be considered in the development of the PHG for these chemicals. If substantive revisions to the original PHG documents are required, the draft documents will be available for discussion in a public workshop and public comment will be solicited as described above in Section B. The final risk assessments will be utilized by DHS in potential revisions to the MCLs for the chemical in drinking water, as described in more detail on the DHS Web site.

E. Descriptions of chemicals or substances for initiation of review: Download a copy of this notice, including Section E: descriptions of chemicals or substances for initiation of review here.