Update: May 2004
Current Massachusetts Regulatory Limit
MMCL = 0.030 mg/L. On June 27, 2002, the Massachusetts DEP Safe Drinking Water Act Advisory Committee decided to adopt the MCL published by the U.S. EPA.
Federal Regulatory Limit
The MCL for uranium is 0.030 mg/L. The MCLG is equal to zero.
Basis for Criteria
The U.S. EPA established an MCL of 0.030 mg/L for uranium in its Radionuclides Final Rule, published in the December 7, 2000 Federal Register (Volume 65, Number 236). This standard became effective on December 8, 2003. Since uranium is radioactive and U.S. EPA uses a non-threshold linear risk model for ionizing radiation, U.S. EPA has set the MCLG for uranium at zero (Fed Reg, 2000). In 1991, U.S. EPA set an MCL for uranium of 0.020 mg/L that was determined to be as close as feasible to the MCLG of zero. In its Final Rule, U.S. EPA did a cost benefit analysis and concluded that the benefits of an MCL of 0.020 mg/L do not justify the costs. U.S. EPA concluded that the MCL of 0.030 mg/L is more appropriate since it maximizes the net benefits (benefits minus costs), while being protective of kidney toxicity and carcinogenicity with an adequate margin of safety (65 FR 76708).
Uranium has been shown to be nephrotoxic in humans and animals. It interferes with readsorption of proteins in the proximal renal tubules of the kidney, resulting in proteinuria. It is not known whether manifestation of this effect is indicative of an incipient adverse effect or if it is a reversible effect that does not typically result in kidney effects (65 FR 76708).
Cancer Assessment: A
Radionuclides emit ionizing radiation, a known human carcinogen, when they radioactively decay. Long-term exposure to radionuclides in drinking water may cause cancer (U.S. EPA, 11/26/02). As with other forms of ionizing radiation, U.S. EPA assumes that uranium has no threshold for carcinogenicity.
PQL: 5 pCi/L
U.S. EPA 908.0 (radiochemical); 908.1 (fluorometric)
PQLs and analytical methods may have been updated since this guidance value was last revised. Updated analytical methods for drinking water and their associated PQLs may be found at http://water.epa.gov/scitech/drinkingwater/labcert/analyticalmethods.cfm.
Other Regulatory Data
Any Health Advisories, Reference Doses (RfDs), cancer assessments or Cancer Potency Factors (CPFs) referenced in this document pertain to the derivation of the current guidance value. Updated information may be obtained from the following sources:
Health Advisories - The U.S. EPA provides guidance for shorter-term exposures for chemicals based on their non-cancer effects. Current health advisories may be more current than those used to derive MCLs and may be found at http://www2.epa.gov/nutrient-policy-data/drinking-water-health-advisory-documents.
RfDs, cancer assessments and CPFs - For specific information pertaining to derivation of drinking water criteria, consult the Federal Register notice that announces the availability of the most current guidance for that chemical. In addition, information on other current RfDs and CPFs as well as cancer assessments for specific chemicals may be found in the U.S. EPA Integrated Risk Information System (IRIS) at http://www.epa.gov/iris/. Please note that the information in IRIS may differ from that used in the derivation process as published in the Federal Register notice.
Federal Register. December 7, 2000. Part II. Environmental Protection Agency. Parts 9, 141, and 142. National Primary Drinking Water Regulations; Radionuclides; Final Rule. (65 FR 76708).
U.S. EPA (U.S. Environmental Protection Agency). October 1, 1989. Integrated Risk Information System (IRIS). Washington, D.C.. http://cfpub.epa.gov/ncea/iris/index.cfm.
U.S. EPA (U.S. Environmental Protection Agency). Last updated November 26, 2002. Radionuclides in Drinking Water. http://water.epa.gov/drink/contaminants/basicinformation/radionuclides.cfm
U. S. EPA (U.S. Environmental Protection Agency). Winter 2004. 2004 Edition of the Drinking Water Standards and Health Advisories.