Fact Sheet: Revised National Recommended Water Quality Criteria for the Protection of Human Health

December 2003

The U.S. Environmental Protection Agency is publishing 15 updated national recommended water quality criteria for the protection of human health:

• chlorobenzene
• cyanide
• 1,2-dichlorobenzene
• 1,4-dichlorobenzene
• 1,1-dichloroethylene
• 1,3-dichloropropene
• endrin
• ethylbenzene
• hexachlorocyclopentadiene
• lindane
• thallium
• toluene
• 1,2-transdichloroethylene
• 1,2,4-trichlorobenzene
• vinyl chloride

These updated criteria are based on the EPA's new methodology for deriving human health water quality criteria (i.e., the 2000 Human Health Methodology) and supersede criteria for these chemicals that the agency had published earlier.

• What are human health water quality criteria?
• How were the fifteen human health water quality criteria updated?
• What are the updated human health water quality criteria?
• Where can I find more information on the updated human health water quality criteria?

What are human health water quality criteria?

Human health water quality criteria are numeric values that protect human health from the harmful effects of pollutants in ambient water. Under section 304(a) of the Clean Water Act, water quality criteria are based solely on data and scientific judgments about the relationship between pollutant concentrations and environmental and human health effects: they do not consider economic or social impacts.

The EPA's national recommended water quality criteria are guidance to states and authorized Tribes in adopting water quality standards in support of the CWA. They also provide guidance to the EPA when it promulgates Federal regulations under the CWA. They are not regulations in themselves and do not impose legally binding requirements on the EPA, states, authorized Tribes or the public.

How were the fifteen human health water quality criteria updated?

The EPA revised the 15 human health water quality criteria based on the agency's methodology for deriving national recommended water quality criteria for the protection of human health (see Methodology for Deriving Ambient Water Quality Criteria for the Protection of Human Health (2000), EPA-822-B-00-004, October 2000). This methodology incorporates significant scientific advances made in the last two decades, particularly in the areas of cancer and noncancer risk assessments, exposure assessments, and methodologies to estimate bioaccumulation in fish.

The updated water quality criteria integrate the national default freshwater/estuarine fish consumption rate of 17.5 grams/day. Thirteen of the criteria integrate a relative source contribution value from the national primary drinking water standards for the same chemicals. The EPA also incorporated a new cancer potency factor for 1,3-dichloropropene and vinyl chloride and a new reference dose for 1,1-dichloroethylene, hexachlorocyclopentadiene, and lindane. These values have already been published in the agency's Integrated Risk Information System. The bioconcentration factors (BCFs) used in deriving today's criteria are consistent with the BCFs used to promulgate human health water quality criteria for priority toxic pollutants in rules such as the 1992 National Toxics Rule and the 2000 California Toxics Rule.

What are the updated human health water quality criteria?

The following table presents the fifteen updated human health water quality criteria:

Where can I find more information on the updated human health water quality criteria?

You can find the most current National Recommended Water Quality Criteria - Human Health Table.

The EPA also established an official public docket for this action (EPA-HQ-OW-2002-0054). The official public docket contains the documents specifically referenced in this action, any scientific views received in response to the December 2002 Federal Register notice, and the EPA's responses to the scientific views submitted by the public.