WASHINGTON, DC, December 18, 2008 (ENS) - The U.S. Environmental Protection Agency should examine whether combined exposures to chemicals known as phthalates could cause adverse health effects in humans, particularly to the male reproductive system, says a new report from the National Research Council.
This analysis, called a cumulative risk assessment, is warranted, said the committee of scientists that wrote the report, if humans are exposed to multiple phthalates at any given time, and if sufficient evidence exists linking exposures to similar adverse health effects.
The committee established that recent studies have shown widespread human exposure to multiple phthalates, including in utero exposure.
Phthalates are esters of phthalic acid and are added to plastics such as polyvinyl chloride, PVC, to increase their flexibility.
Phthalates are used in a wide variety of consumer products, such as cosmetics and personal care products, medical devices such as blood IV bags and tubing, children's toys, and building materials.
In view of public 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.
The National Research Council report came in answer to an EPA request for a recommendation on whether the agency should conduct a cumulative risk assessment for phthalates, and if so, how it should be framed. The National Research Council report is only a recommendation in favor of an assessment, not a comprehensive profile on the health effects of phthalates.
The committee recommends that the 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 physical structure, which is EPA's current practice.
Furthermore, wrote the committee, EPA should consider using the recommended approach for future cumulative risk assessments on other kinds of chemicals.
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.
Chaired by Deborah Cory-Slechta, a professor in the Department of Environmental Medicine at the University of Rochester School of Medicine, the committee found that recent animal studies have increased understanding of the potential risks from phthalates, although few human studies on the health effects of phthalates are available.
The committee reviewed animal research and found that exposure of male lab rats to various phthalates produced infertility, undescended testes, malformation of the penis, and other reproductive tract malformations.
The severity of effects differs among phthalates - some exhibit less severe or no effects. The age of the animals at the time of exposure is critical to the severity of the effects. The fetus is most sensitive.
The animal studies also indicated that some phthalates reduce testosterone concentrations. Depending on when this drop occurs, it can cause a variety of effects in animals that are critical for male reproductive development.
Other chemicals known as antiandrogens, which prevent or inhibit male hormones from working, can produce similar effects in lab animals.
The committee recommended that phthalates and other chemicals that affect male reproductive development in animals, including antiandrogens, be considered in the cumulative risk assessment.
"A focus solely on phthalates to the exclusion of other chemicals would be artificial and could seriously underestimate risk," the committee emphasized.
Given that multiple human exposures to phthalates occur and that research shows exposure to different phthalates leads to similar outcomes in lab animals, the committee recommended a cumulative risk assessment.
Chris Bryant, managing director of the Chemical Products & Technology Division of the American Chemistry Council, an industry association, said of the report, "Congress has asked the Consumer Product Safety Commission (CPSC) to conduct a cumulative risk assessment on phthalates and there is a question as to whether a simultaneous EPA study would be redundant."
Some hospitals, consumer product companies, and government purchasers have taken the first steps to replace PVC plastics containing phthalates with safer alternatives. The Campaign for Safe Cosmetics says Revlon, L'Oreal and other cosmetic companies are phasing out phthalates in nail polish, and 300 cosmetic companies have pledged to eliminate phthalates in their products in response to consumer demands.
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