Prioritizing Chemicals

Commercial chemicals have gotten lots of attention from the Environmental Protection Agency in the past two years—and more is coming.

In 2009, Administrator Lisa P. Jackson directed the agency to come up with action plans to address controversial chemicals or classes of substances, including phthalates and perfluorinated compounds. That work, which is expected to result in regulation of at least some of the chemicals under the Toxic Substances Control Act, is well has resulted in 11 action plans.

Now, EPA is seeking out more chemicals that deserve close scrutiny by regulators—and potentially could be regulated. The agency intends to identify the next batch of substances by the end of 2011 and to review and assess them in 2012, according to Wendy Cleland-Hamnett, director of EPA’s Office of Pollution Prevention & Toxics. She spoke at a Sept. 7 EPA webinar about the agency’s efforts to identify what the agency dubs “priority chemicals” for further review and assessment.

EPA is planning a two-step process for selecting priority chemicals. In the first step, the agency will pick out substances that meet at least one of six factors. One is that a chemical is linked to adverse reproductive or developmental effects. Another is if a substance is persistent, bioaccumulative, and toxic. A third criterion covers probable or known carcinogens. Two other factors are whether a chemical is found in children’s products or consumer products. The final one is for chemicals detected in human blood, urine, or tissue in biomonitoring programs.

For the first step, EPA will rely heavily on data from other government agencies, such as those from the National Toxicology Program and the International Agency for Research on Cancer. EPA will also draw on its own Integrated Risk Information System and the exposure and use information that chemical manufacturers submitted to the agency for 2006, the most recent data available.

Cleland-Hamnett described the first step as a coarse sieve to identify substances that could become priority chemicals.

In the second step, the agency will take a closer look at the substances that made the first cut and then rank them in order of priority, she said. Those posing the greatest risk will be at the top of the list. In this step, EPA will use data from more sources than in the first, including toxicology information submitted to EPA by chemical producers and exposure and use information that a new regulation requires these companies to supply to the agency next year ( C&EN, Aug. 8, page 30).

Overall, the effort is expected to involve hundreds of substances, not thousands, Cleland-Hamnett said. The agency wants to keep the screening effort narrowly focused on chemicals of high concern, she added.

During the webinar, representatives of the chemical industry and health advocacy groups offered a number of suggestions about how the agency should go about the selection process.

Some suggested additional factors that would likely boost the number of chemicals identified in the first step. For instance, EPA should include compounds identified as endocrine disrupters, said Carol Kwiatkowski. She is executive director of the Endocrine Disruption Exchange, a nonprofit that provides information on substances that interfere with the hormone system. Other commenters suggested that EPA include substances that can cause damage to the nervous system.

Some suggestions might reduce the number of substances captured in the first step of the process. For example, Derek D. Swick, senior policy adviser at the American Petroleum Institute (API), said EPA should give a lower priority to chemicals that the agency already regulates.

Other participants in the webinar focused on how EPA determines exposure to chemicals. The agency should consider the production volume of a substance in its exposure estimates, said Mark A. Mitchell, a physician with the National Medical Association, which promotes interests of physicians and patients of African descent. He pointed out that many poor and minority communities historically have ended up with exposure to toxic chemicals that was never anticipated. Thus, use of production volumes may lead to better estimates of exposure, Mitchell said. Kwiatkowski agreed, and suggested the agency use global production volumes for a chemical, not just domestic output, in exposure estimates.

But API’s Swick urged EPA not to use production volume as a means of estimating exposure. To classify a chemical as a priority for further assessment, he continued, EPA should have in hand actual data on a substance’s hazard and exposure.

EPA’s Cleland-Hamnett responded that the chemical ranking effort will be based on risk, which factors in both hazard and exposure information. “If there’s a chemical identified that has high hazard but we can’t identify significant exposure, it’s not likely to end up being a priority chemical,” Cleland-Hamnett said. Similarly, if there is no evidence that a substance is hazardous, “it wouldn’t end up as a priority chemical” regardless of how much people or the environment are exposed to it, she said.

James R. Cooper, vice president for petrochemicals at the National Petrochemical & Refiners Association, asked EPA to publish the criteria it will use to judge its confidence in the sources of hazard and exposure data, including information from government agencies. Such a move would enable the public to gain a better understanding of the agency’s process of selecting chemicals for priority assessments, he said.

Other participants in the webinar recommended that EPA work with other regulatory agencies involved in chemical assessment. For instance, API’s Swick said EPA should coordinate with the European Chemicals Agency, which has been collecting hazard and exposure data under the European Union’s Registration, Evaluation, Authorisation & Restriction of Chemical substances program. A staff member from the Department of Homeland Security said during the webinar that as part of an analysis of the chemical sector, the agency is ranking substances on the basis of their toxicity. DHS can share details of its work, which is classified, with EPA, she said.

State regulators also invited EPA to take advantage of their work on chemicals.

In a move separate from the webinar, the American Chemistry Council, a trade association of chemical manufacturers, is suggesting a method that EPA could use in selecting priority chemicals. On Sept. 6, ACC unveiled a tool that gives scores to chemicals based on their toxicity and their potential for exposure.

If hazard data are lacking for a chemical, EPA could study the compound’s structure-activity relationship to appraise its toxicity, said Christina Franz, director of regulatory and technical affairs at the chemical industry group. If no other data are available about the substance’s toxicity, the ranking tool would automatically give it a high hazard ranking. This aspect of the tool would be an incentive for chemical manufacturers to provide EPA with any privately held data they have that show their products pose no or low toxicity, Franz explained.

The scores derived from the tool, along with professional judgments from EPA’s staff, would determine which substances should undergo review first, according to Franz.

EPA has not yet commented on ACC’s ­proposal.