A national science panel says that the current approach of determining health risks from phthalates understates their potential risks. The report calls for regulators to look collectively at all chemicals that can contribute to a particular type of risk that phthalates can potentially cause.
The National Research Council report, issued Dec. 18, said all chemical risks should be assessed by what it calls a cumulative risk approach.
NRC is part of the National Academies of Sciences and did the study at the request of the U.S. Environmental Protection Agency.
The report is ``a clear directive to the EPA that we will continue to underestimate the risk of chemicals if we keep addressing them one by one,'' Sarah Janssen, a reproductive scientist and physician in the San Francisco office of the Natural Resources Defense Council, said in a telephone interview.
``We live in the real world where we are exposed to multiple chemicals from multiple sources every day.
``We need to consider all the toxic chemicals that we are exposed to, starting before birth and continuing throughout our lives,'' Janssen said.
Janssen also said the report should serve as a ``wake-up call'' to other government agencies, such as the Food and Drug Administration and the Consumer Product Safety Administration, that are charged with protecting the public health.
Specifically for phthalates, the subcommittee said there was ``sufficient evidence'' to conduct a cumulative risk assessment and recommended the study include other chemicals that disrupt the production of androgen. Those include several chemicals that go into fungicides, some polychlorinated biphenyls, 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), polybrominated diphenyl ethers, and androgen receptor antagonists such as vinclozolin and procymidone.
``We feel it is important for risk assessment to focus on common adverse outcomes,'' said Deborah Cory-Slechta, a member of the EPA science advisory staff and chair of the NRC Committee on the Health Risks of Phthalates.
``A focus on only a specific pathway or single chemical can lead to too narrow of an approach. There are multiple pathways of producing a similar effect,'' she said. ``We feel it is important to include all of those'' in assessing health risks from chemicals.
``Cumulative risk assessments for phthalates should be expanded to include all phthalates and chemical agents that cause the same adverse effect,'' said Cory-Slechta.
Most research has shown that greatest health risks are from phthalates with carbon chains of four to six. However, Cory-Slechta said, ``There is evidence if you look just at one phthalate and the combined effect of all them is not taken into consideration that you would underestimate the risk.''
Tim Zacharewski, a toxicologist at Michigan State University and an expert on endocrine disrupting chemicals, disagreed. ``It is important to make distinctions between the different types of phthalates [because] there are a large class of chemicals with differing toxicity profiles.''
Tim Lee, director of legal and public affairs for the Center for Individual Freedom in Alexandria, Va., questioned the credibility of the report. Only two of the five subcommittee meetings were open to the public; BASF Corp. was the only chemical company asked for its input; and Lee said two subcommittee members, Dr. Maida Galvez and Dr. Mary Wolff, both doctors at Mount Sinai School of Medicine in New York, are anti-phthalate activists.
``Given these outstanding concerns, I would give the report very, very little credibility,'' Lee said. ``Our letters to the NRC weren't included in the public comments. We don't know what to believe because it has been done behind closed doors and under a veil of secrecy. So you have to look at it with a skeptical eye when someone is stonewalling you. It raises red flags.''
The American Chemistry Council in Arlington, Va., said it has ``some reservations'' about how someone would conduct a cumulative risk assessment.
``This essentially would result in a study without limits,'' ACC said in a statement from Chris Bryant, managing director of its Chemical Products and Technology Division.
NRC did not do any new research for its report and based all its conclusions on a single area of focus. ``All of our judgments were based on data that was related to the risk of phthalates on the development of reproductive systems in males,'' said Cory-Shlecta.
A federal ban on toys and child-care products containing six types of phthalates goes into effect Feb. 10. California has a similar phthalate ban that goes into effect Jan. 1, and Washington and Vermont have bans that go into effect July 1.