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About Chemical Prioritizations
Overview
Under ChAMP, EPA evaluates and assigns priority for follow-up action on high production volume (HPV) and medium production volume (MPV) chemicals and will initiate action where appropriate. EPA develops prioritizations for individual chemicals or a group of chemicals that are similar in some way, e.g., structure, properties, toxicity. Depending on the availability of screening-level information to characterize hazard, exposure and risk, EPA produces either a risk-based prioritization (RBP) or a hazard-based prioritization (HBP). These assessments include EPA prioritization of chemicals for follow-up data collection or management actions based upon their potential risks and hazards.
These prioritizations do not constitute definitive determinations regarding hazard or risk or the sufficiency of available information for any regulatory purpose, but are rather initial evaluations of data and understanding currently available to EPA.
Read the reports on decisions already made for Risk-Based Prioritizations and Hazard-Based Prioritizations, together with the identification of any prospective follow-up action.
Differences between Risk-Based and Hazard-Based Prioritizations
EPA develops RBPs for chemicals for which adequate hazard and exposure/use information is available. This will typically include all chemicals sponsored through the EPA's HPV Challenge Program and Organisation for Economic Cooperation and Development (OECD) HPV Programs 
regardless of whether they are HPV or MPV on the 2006 Inventory Update Reporting (IUR).
EPA is also developing HBPs. Most, but not all, HBPs will be for chemicals identified as MPV on the 2006 IUR. Most MPV chemicals were not included in requirements for the submission of processing or use information under the IUR, and are therefore less likely to have information available to develop exposure and risk characterizations to support a risk-based prioritization.
Further, since most MPV chemicals were not part of the HPV Challenge Program, they are also less likely to have a complete set of basic screening-level hazard data available. Therefore, they may be clustered with chemicals of similar structure and toxicity, and EPA will use predictive methods in developing the screening-level hazard characterization.
Finally, HBPs may be developed for those chemicals that were identified as HPV on the 2006 IUR, but for which an HPV Challenge data set (Screening Initial Data Set; SIDS) is not available. Industry has sponsored some of these HPV chemicals for collection of the SIDS under the industry initiated, extended HPV Program (EHPV) .. When these data become available, it may be possible to develop an RBP for these chemicals.
Risk-Based Prioritizations
RBPs are developed for chemicals that were part of the HPV Challenge Program or the OECD HPV Program and also for chemicals reported as MPV on the 2006 IUR but for which a robust hazard data set (i.e. SIDS) and use and exposure information is available. In other words, an RBP will be developed for all chemicals reported as MPV or HPV on the 2006 IUR if hazard and use/exposure information equivalent to that collected under the HPV Challenge and IUR, respectively, are available.
RBPs for individual chemicals or chemical categories include a qualitative prioritization decision and a qualitative screening-level risk characterization on which the prioritization decision is based. The screening-level risk characterization is developed based on screening-level hazard and exposure characterizations prepared by EPA using data submitted by chemical sponsors under the HPV Challenge Program (or the OECD HPV Program), information submitted under the 2006 Inventory Update Reporting (IUR), and information readily available from publicly accessible databases.
RBPs summarize, qualitatively (high, medium, low), the potential risks of a chemical or chemical category; identify additional information relevant to the Agency's assignment of a high, medium, or low priority for further attention; and present potential future actions. A detailed description of the RBP process, including information on the rationale for characterizing hazard, exposure and risk as high, medium, or low is available in the Methodology for Risk-Based Prioritization Under ChAMP (PDF) (28 pp., 171 KB, About PDF) .
RBP Decisions and Follow-Up
EPA's screening-level evaluations, combined with additional relevant information, including existing regulations and ongoing activities, result in one of three possible risk-based priority decisions:
- Low Priority, Follow-Up Action Not Suggested at this Time: Information available to EPA on the chemicals or categories assigned to this priority suggests that they do not present significant risk issues that warrant further Agency consideration at this time. This prioritization category may include chemicals with known risks that are already being controlled or addressed by existing activities or regulations. EPA generally does not expect to follow up with voluntary or regulatory actions in the near future for low-priority chemicals. EPA would re-evaluate a low priority decision if new data or information became available that contraindicated a low-priority decision.
- Medium Priority: Information available to EPA on chemicals assigned to this priority suggests possible concerns, but with risk issues or uncertainties that might be resolved if additional data (e.g., on exposures, controls, and/or hazards) were available to provide a basis for evaluating the potential concerns. EPA will encourage voluntary actions to better understand or mitigate potential risks for medium priority chemicals and may identify the need to act directly via regulatory means.
- High Priority: Information available to EPA on chemicals assigned to this priority suggests that these chemicals appear to have more serious potential risk concerns. EPA will determine whether there is a need for risk management actions, regulations, and/or more comprehensive data. EPA will encourage prompt voluntary actions to better understand or mitigate potential risks for high-priority chemicals and will also identify the need to act directly via regulatory means.
As warranted, EPA may nominate some of these chemicals for inclusion in appropriate Federal research or assessment programs, such as the National Toxicology Program (NTP)
, the Integrated Risk Information System (IRIS), or the National Health and Nutrition Examination Survey (NHANES) . EPA also intends to factor in non-domestic data development efforts that are likely to provide needed information (e.g., Canadian or European efforts). EPA regulatory actions to address high-priority chemicals might include, where appropriate:
- Initiation of proceedings for Section 4 test rules or Section 8 rules under the Toxic Substances Control Act (TSCA) to collect additional data for chemical assessment;
- TSCA Section 6 rules to mandate new labeling requirements or other risk controls;
- TSCA Section 5 (a)(2) significant new use rules (SNURs) to ensure notice and to limit future risks; or
- Other actions.
Hazard-Based Prioritizations (HBP)
HBPs are developed primarily for MPV chemicals. This is because most MPV chemicals are produced below the production volume for which exposure and use information is required under the IUR (i.e. 300,000 pounds per year). Without this information, developing an exposure characterization to support a risk-based characterization is not possible.
HBPs for individual chemicals or chemical clusters include a prioritization decision and its underlying screening-level hazard characterization. The screening-level hazard characterization is based on characterization of environmental fate and potential health and environmental hazards derived from existing data available to EPA. For many MPV chemicals, these data are limited. In such cases, EPA uses a number of predictive tools and methods to characterize properties and hazards in developing fate and hazard characterizations.
In some cases, HBPs may be developed for chemicals that are HPV on the 2006 IUR. This may occur for chemicals that were not part of HPV Challenge or OECD HPV programs and for which the hazard data that are used for developing an RBP (i.e., Screening Initial Data Set) are therefore not currently available. In these cases, the HBP would also include a summary of IUR production volume information, and if available (i.e. if chemical is produced at greater than 300,000 pounds per year), reported use information.
HBPs summarize the potential hazards of a chemical or chemical cluster; identify additional information relevant to the Agency's assignment of a high, medium, or low priority for further attention; and present potential future actions. A detailed description of the HBP process, including information on how chemicals are clustered and on how data gathering, review, and characterization are performed, is available in the Methodology for Hazard-Based Prioritization Under ChAMP (PDF) (17 pp., 242 KB, About PDF) .
HBP Follow-Up
Given the general limitations on currently available hazard and exposure information used to make HBPs, EPA anticipates that data gathering would be the most common follow-up action on medium- and high-priority HBP chemicals. As appropriate, EPA may:
- Request voluntary data submissions
- Refer chemicals to the Interagency Testing Program
- Propose data collection under Section 4 or Section 8 of TSCA
- Identify other related voluntary or regulatory information collection activities
Prioritization Decisions
Read summaries of RBP (PDF), (9 pp., 56 KB, About PDF) and HBP (PDF), (4 pp., 32 KB, About PDF) decisions made by EPA to date.