TSCA Plan Prioritizes Substances

In its latest effort to exercise its limited authority to regulate existing chemicals, EPA has issued a work plan that names 83 substances that will undergo risk assessments in the next several years. The first seven on the chemical list will be assessed in 2012. If the assessments indicate unacceptable risk to public health, the Agency states that it will take action to manage the risk. The risk management measures the Agency decides to employ will be of great interest to chemical companies.

EPA states that inclusion of a chemical in the work plan does not itself constitute a finding by the Agency that the chemical represents a risk to human health or the environment. Such a determination must be the result of the planned risk assessments. Identification of the chemical in the work plan simply means that the Agency intends to consider it for further review.

“Identifying these chemicals early in the review process would afford all interested parties the opportunity to bring additional relevant information on those chemicals to the Agency’s attention to further inform the review,” states EPA. “To take risk management actions on a chemical substance under various sections of [the Toxic Substances Control Act, (TSCA)], the Agency would have to make the appropriate finding required by the specific provisions of the statute.”

The work plan represents a new approach by EPA to prioritize chemicals for further review. The process began in September 2011 when the Agency conducted an on online discussion forum and invited comments on a draft guide on identifying priority chemicals for review and assessment. The guide described a two-step process for identifying chemicals. Step 1 listed prioritization factors, discussion questions, data sources, and factors that would inform prioritization decisions. Under Step 2, the Agency selected specific chemicals for assessment, data sources for further analysis, and discussion questions.

Starting Small

Prioritizing assessments of existing chemicals has been viewed as critical since there are more than 84,000 chemicals in commerce. EPA does little if any chemical testing on its own, and use of authoritative sources of health and environmental information must be an essential part of the process. The work plan addresses the challenge by developing decision criteria that are then informed by the data sources in a way that produces a manageable number of chemicals at the beginning of the process. Here’s how one stakeholder, the National Petroleum and Refiners Association (NPRA), put it in the online forum:

“The ultimate goal of priority-setting is to allow EPA to focus its resources; therefore, casting a wide net and considering an abundance of different factors too early in the process will only make achieving the agency’s objectives more challenging. Considering all the factors proposed under this [discussion forum] would result in an initial cut that includes most chemicals subject to [the TSCA inventory update rule (IUR)] reporting, which would put EPA right back at the starting point. NPRA recommends that EPA keep it simple in the first and second tiers, consider the factors that the agency has proposed to develop a ‘quick-start’ list of chemicals for immediate review and movement through the tiers, and move forward in a deliberate and transparent manner. Other factors could be added in subsequent tiers to help refine screening-level assessments and look at a fuller array of potential hazards and exposure pathways.”

This sentiment was shared by Richard Dennison, a scientist with the Environmental Defense Fund, who has argued cogently for decades on the need for TSCA reform. According to Dennison:

“EPA has been clear that a comprehensive review and ranking of all chemicals in commerce is beyond its current authority and resources, and that any such effort – to the extent it is desired – must await TSCA reform. Clarity as to the more limited purpose of EPA’s current initiative is important to note for two reasons. First, it means that EPA is not claiming that chemicals it identifies as priorities are necessarily those that have somehow been shown to pose the greatest risk in comparison to all other chemicals. Rather, they are chemicals for which there is sufficient evidence or reason for concern that they warrant further scrutiny. And, of course, in order to actually regulate the production or use of such chemicals, EPA would have to meet the very high burdens imposed on it under TSCA.”

Bounded by TSCA

EPA’s major restriction in assessing existing chemicals is that TSCA forces the Agency to demonstrate certain health or environmental risks before it can require companies to further test their chemicals and undertake risk management. Specifically, chemical companies are not required to develop and submit toxicity information to EPA on existing chemicals unless the Agency finds that a chemical may present an unreasonable risk of injury to human health or the environment or is or will be produced in substantial quantities and that either there is or may be significant or substantial human exposure to the chemical, or the chemical enters the environment in substantial quantities. EPA must also determine if there are insufficient data on a chemical to reasonably determine its effects on health or the environment and that testing is necessary to develop such data before the Agency can require a company to test its chemicals for harmful effects. This structure places the burden on EPA to demonstrate a need for data on a chemical’s toxicity rather than on a company to demonstrate that a chemical is safe.

While EPA believes that the long-term challenge of assessing the safety of commercial chemicals can be best achieved through legislative reform of TSCA, the Agency says its current authority can be used to create a sustained and effective existing chemicals program. Based on stakeholder comments, the process described in the work plan appears to be the best approach the Agency has yet mounted in achieving that goal.

Two-Step Process

EPA began the two-step process for prioritizing chemicals for risk assessment by developing the following “factor criteria:”

• Chemicals identified as potentially of concern for children’s health (e.g., chemicals with reproductive or developmental effects).
• Chemicals identified as persistent, bioaccumulative, and toxic (PBT).
• Chemicals identified as probable or known carcinogens.
• Chemicals identified as probable or known neurotoxins.
• Chemicals used in children’s products.
• Chemicals used in consumer products.
• Chemicals detected in biomonitoring programs.

In Step 1, EPA used specific sources of information for each of the above factors to develop a candidate chemical list. For example, for neurotoxicity, the Agency referred to its own Integrated Risk Information System (IRIS) database, which contains information on the human health effects that may result from exposure to 550 chemical substances. IRIS was also used as a source for carcinogens along with data from the National Toxicology Program and the World Health Organization’s International Agency for Research on Cancer. Information on biomonitoring was obtained from the National Report on Human Exposure to Environmental Chemicals of the Centers for Disease Control while California’s Proposition 65 and Washington State’s list of chemicals of high concern were used to identify chemicals to which children may be exposed.

Using the information sources, EPA produced a list of 1,235 chemicals, each of which met at least one factor criterion. Duplicate chemicals were screened out as well as those that EPA did not find appropriate for near-term review. Also dropped from the Step 1 list were chemicals subject to other statutes, such as pesticides, drugs, certain radioactive materials, metals, and chemicals being assessed in other EPA action plans or subject to significant regulation under TSCA. Screening reduced the number of candidate chemicals to 345.

Additional screening was conducted in Step 2. Here chemicals received a score based on three characteristics – hazard, exposure, and potential for persistence and/or bioaccumulation. For example, hazard relates mainly to the toxicity of the chemical, which was classified as high, medium, or low with corresponding scores of 3, 2, and 1. A chemical that is a known, presumed, or suspected carcinogen would be scored 3. If there is limited evidence that a chemical is a carcinogen, the score would be 2. A non-carcinogen would receive a score of 1. The exposure score was based on a combination of chemical use, general population and environmental exposure, and release information. For example, the release score was based on data for chemicals subject to EPA’s toxics release inventory (TRI) reporting. Persistence scoring consisted mainly of evaluation of the chemical’s potential half-life in air, water, sediment, and soil. The bioaccumulation score consisted of evaluation of bioaccumulation and bioconcentration factors. (For example, a bioaccumulation factor is the ratio of contaminant concentration measured in a specimen to the concentration measured in the surrounding water.) Step 2 lowered the candidate list to 83 chemicals.

First-year Chemicals

To identify chemicals for work in any given year, EPA considers a number of factors, including whether a chemical was ranked as high; whether the chemical reflects more than one of the factors in Step 1; whether certain chemicals would benefit from preliminary work prior to a risk assessment; whether certain chemicals have been previously assessed and would be more appropriate for risk assessments in later years; and how EPA’s resources match up with the job of assessing specific chemicals. The seven chemicals identified for assessment in 2012 are:

• Antimony and antimony compounds
• HHCB (1,3,4,6,7,8-Hexahydro-4,6,6,7,8,8,-hexamethylcyclopenta[g]-2-benzopyran)
• Long-chain chlorinated paraffins
• Medium-chain chlorinated paraffins
• Methylene chloride
• N-methylpyrrolidone
• Trichloroethylene

EPA says it anticipates issuing draft risk assessments as they are completed for these chemicals, at which time the public will have the opportunity to comment. If an assessment indicates significant risk, EPA says it will “evaluate and pursue appropriate risk reduction actions.” If an assessment indicates no significant risk, the Agency says it will conclude its current work on that chemical. The Agency adds it will soon identify specific chemicals for risk assessments in 2013 and 2014.

EPA’s TSCA Work Plan Chemicals is at http://www.epa.gov/oppt/existingchemicals/pubs/wpmethods.pdf.