Report Urges EPA to Examine Health Effects of Chemicals in Plastics
EPA should examine whether combined exposures to chemicals known as phthalates could cause adverse health effects in humans, concludes a new report from the National Research Council. In addition, this analysis, called a cumulative risk assessment, should consider other chemicals that could potentially cause the same health effects as phthalates, instead of focusing on chemicals that are similar in structure, which is EPA's current practice. Furthermore, EPA should consider using the recommended approach for future cumulative risk assessments on other kinds of chemicals.
Phthalates are used in a wide variety of consumer products, such as cosmetics, medical devices, children's toys, and building materials. In light of concerns, the European Union and the United States have passed legislation that restricts the concentrations of several phthalates in children's toys, and the European Union also has banned several phthalates from cosmetics. EPA asked the Research Council to recommend whether it should conduct a cumulative risk assessment for phthalates, and if so, how it should be framed. Accordingly, the National Research Council report is not a comprehensive profile on the health effects of phthalates.
Recent animal studies have increased understanding of the potential risks from phthalates, although few human studies on the health effects of phthalates are available, said the committee that wrote the report. To decide whether a cumulative risk assessment is warranted, two factors needed to be determined: whether humans are exposed to multiple phthalates at any given time, and whether sufficient evidence exists to link exposures to similar adverse health effects.
Currently when conducting cumulative risk assessments, EPA often considers only chemicals that are structurally related, on the assumption that they have the same chain of reactions that lead to a final health outcome. That practice ignores how exposures to different chemicals may result in the same health effects. The conceptual approach taken for phthalates -- to consider chemicals that cause similar health effects -- should also be applied when completing any cumulative risk assessment, the committee said. For instance, EPA could evaluate the risk of combined exposures to lead, methylmercury, and polychlorinated biphenyls because all contribute to cognitive deficits consistent with IQ reduction in children.
In addition, further research should be conducted to allow greater refinement of the cumulative risk assessment associated with phthalates and reduce uncertainty associated with such an assessment, the report says. Moving beyond the constraints of grouping chemicals based on structural similarity may appear challenging, but it is feasible to evaluate the multiplicity of human exposures. It also directly reflects EPA's mission to protect human health, the committee noted. Such a shift in approach would entail substantial efforts by EPA, such as defining and setting priorities among the most prominent adverse health effects. However, a focus on similar outcomes facilitates the process by identifying the groups of chemicals that should be included, the committee said.
More information on the report, "Phthalates and Cumulative Risk Assessment -- The Task Ahead," can be found at http://www.nap.edu/catalog.php?record_id=12528#toc.