|  | Water Quality Criteria            Recent                                                                                Additions | Contact                                                                                Us |                                                                                Print                                                                                Version                                                                                Search:                                                                                EPA                                                                                Home > Water > Water                     Science > Water Quality                     Criteria > Human Health > Methodology                     > Fact Sheet |
|--|----------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|

| Human HealthFact Sheet: Methodology United States                     Environmental Protection                    Agency Office of Water                    4304EPA-822-F-00-005                    October 2000 Revised Methodology for Deriving Health-Based Ambient               Water Quality Criteria (2000)Abstract
The U.S. Environmental Protection Agency is publishing revisions               to the 1980 Ambient Water Quality Criteria National Guidelines to               better protect human health. The 1980 Ambient Water Quality Criteria               National Guidelines outline the methodology used by states and tribes               to develop human health water quality criteria. Revisions to the               1980 guidelines incorporate significant scientific advances in key               areas such as cancer and non-cancer risk assessments, exposure assessments,               and bioaccumulation in fish. The revised methodology will provide               more flexibility for decision-making at the state, tribal and EPA               regional levels. It is most likely that the methodology will result               in more stringent criteria for bioaccumulatives and generally similar               values of nonbioaccumulatives. 
Human Health Water Quality Criteria
Human health ambient water quality criteria (AWQC) are numeric               values limiting the amount of chemicals present in our nation's               waters. Human health criteria are developed under Section 304(a)               of the Clean Water Act of 1972 and are designed to protect human               health. Water quality criteria are developed by assessing the relationship               between pollutants and their effect on human health and the environment.               These criteria are used by states and Indian tribes to establish               water quality standards and ultimately provide a basis for controlling               discharges or releases of pollutants. 

 The Clean Water Act (CWA) requires EPA to develop, publish and               revise ambient water quality criteria (AWQC). In 1980, EPA published               AWQC for 64 pollutants/pollutant classes and provided a methodology               for deriving the criteria. These national guidelines addressed three               types of endpoints: noncancer, cancer and organoleptic (taste and               odor) effects. 

 The states and tribes use these criteria to develop water quality               standards for each water body. EPA is required to review periodically               criteria adopted by states and tribes. The revisions to the EPA's               1980 methodology will help states and tribes establish water quality               criteria and standards that protect human health. They provide detailed               means for developing water quality criteria, including systematic               procedures for evaluating cancer risk, noncancer health effects,               human exposure, and bioaccumulation potential in fish. 
 EPA Methodology for Deriving Criteria
States and tribes must develop water quality standards that include               designated uses and water quality criteria necessary to support               those uses. The Methodology is the guidance for states and tribes               to help them establish water quality criteria and standards to protect               human health. It provides detailed means for developing the water               quality criteria, including systematic procedures for evaluating               cancer risk, noncancer health effects, human exposure, and bioaccumulation               potential in fish. 

 Risk assessment practices have evolved significantly since 1980,               particularly in the areas of cancer and noncancer risk assessments               (with new information, procedures, and numerous published Agency               guidelines), exposure assessments (with new studies on human intake               and exposure patterns, and new science policy guidelines) and methodologies               on accounting for bioaccumulation in fish. 
 General Background of the Revision Process
Revisions began with a national workshop in 1992, where participants               discussed critical issues. Based on individual expertise, attendees               were assigned to technical workgroups including cancer risk, noncancer               risk, exposure, and bioaccumulation in fish. 

 EPA submitted recommendations from the workshop for review and               comment by the EPA Science Advisory Board. EPA created a workgroup               in 1994, including program office and regional participants, to               revise the methodology. Numerous stakeholder participation activities               were conducted between 1995 and 1998, including presentations to               the Federal-State Toxicology and Risk Analysis Committee and several               multi-regional water quality coordinator's meetings in 1996 and               1997, which included participants from EPA regions, states, tribes               and some industry. 

 Following publication of the draft Methodology revisions, written               public comments were accepted. Further presentations included the               1998 Annual Meeting of the Society For Risk Analysis and the 1999               Annual Meeting of the Society of Toxicology. In May 1999, a peer               review workshop was held. A public stakeholders meeting was also               held then. EPA received extensive input on the Methodology from               each of these groups. EPA considered all comments and incorporated               a substantial portion of them into the final AWQC Methodology Revisions.             
 Major Methodology Revisions
Publication of final revisions satisfies the requirements of the               CWA that EPA periodically revise criteria for water quality to reflect               accurately the latest scientific knowledge on the kind and extent               of all identifiable effects on health and welfare that may be expected               from the presence of pollutants in any body of water. These Final               AWQC Methodology Revisions to the 1980 AWQC National Guidelines               are necessitated by the many significant scientific advances made               during the past 20 years in the key areas of cancer and noncancer               assessments, exposure assessments, and bioaccumulation in fish.             

 The major revisions are in four assessment areas: cancer, non-cancer,               exposure, and bioaccumulation. 

 For carcinogen (cancer) risk assessment: 
- Recommend more sophisticated methods to comprehensively determine                 the likely mechanism of human carcinogenicity. 
Recommend a mode of action (MOA) approach to determine the most                 appropriate low- dose extrapolation for carcinogenic agents. 

 For noncarcinogens: 
- Use EPA guidance on assessing noncarcinogenic effects of chemicals                 and for the Reference Dose (RfD) derivation. 
Recommend consideration of other issues related to the RfD process                 including: integrating reproductive/ developmental, immunotoxicity,                 and neurotoxicity data into the calculation. 

Recommend the use of quantitative dose-response modelling for                 the derivation of RfDs. 

 Provide guidance for states and tribes on the use of an alternative                 value from the RfD point estimate, within a limited range, to                 reflect the inherent imprecision of the RfD. 

 For exposure assessment: 
- Encourage states and tribes to use local studies on fish consumption                 that better reflect local intake patterns and choices. 
Recommend default fish consumption values for the general population,                 recreational fishers and subsistence fishers. 

Account for other sources of exposure, such as food and air,                 when deriving AWQC for noncarcinogens and nonlinear carcinogens.               

 For bioaccumulation: 
-  Focus on the use of bioaccumulation factors (BAFs), instead                 of bioconcentration factors (BCFs) for estimating potential human                 exposure to contaminants via the consumption of contaminated fish                 and shellfish. 
Use high quality field data over laboratory or model-derived                 estimates for deriving BAFs, since field data best reflect factors                 which can affect the extent of bioaccumlation (e.g., chemical                 metabolism, food web structure). 

 EPA does not plan to completely revise all of the criteria developed               in 1980 or those updated as part of the 1992 National Toxics Rule.               Partial updates of all criteria may be necessary. EPA will continue               to develop and update toxicology and exposure data needed in the               derivation of AWQC that may be impractical for the states and regions               to obtain. 
 Methodology Revisions Implementation by EPA/States
EPA's future role in developing AWQC for the protection of human               health will include: 
- The development of revised criteria for chemicals of high priority                 and national importance (including, but not limited to, chemicals                 that bioaccumulate, such as PCBs, dioxin, and mercury). 
- The development or revision of AWQC for some additional priority                 chemicals. 
- Technical assistance to states and tribes on the toxicology,                 exposure and bioaccumulation methods, and review of state/tribal                 water quality standards. 

EPA encourages states and tribes to use the revised methodology               to develop or revise AWQC to reflect local conditions appropriately.               EPA believes that AWQC inherently require several risk management               decisions that are, in many cases, better made at the state and               regional level (e.g., fish consumption rates, target risk levels).             
 Effect on State and EPA Regional Offices
The revised methodology will provide more flexibility for decision-making               at state, tribal and EPA regional levels. EPA believes the AWQC               require several risk management decisions that are often better               made at the state, tribal and regional level. The methodology will               probably result in more stringent criteria for bioaccumulatives               (due to the use of BAFs instead of BCFs) and generally similar,               or less stringent, values of nonbioaccumulatives. 
 Information
For additional information concerning these recommended methodology               revisions, contact Denis R. Borum, Health and Ecological Criteria               Division (4304), Office of Science and Technology, U.S. Environmental               Protection Agency, 1200 Pennsylvania Ave., N.W., Washington, D.C.,               20460. 

 You may view the Federal Register (FR) Notice and the AWQC Methodology               revisions on the Internet at:                http://www.epa.gov/waterscience/humanhealth. The FR Notice explains               how to obtain additional information and how to review the complete               administrative record for these Methodology revisions. 

  

 

Water Quality Standards | Drinking Water | Research and Development
 
EPA Home |                                Privacy and                                Security Notice |                                Contact Us

 

  |
|------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------------|