Daily Green – Phthalates, a class of hormone-mimicking chemicals found in toys, cosmetics, air fresheners, plastics and other common household products, need urgent study, according to the National Research Council. Americans are exposed to phthalates and other potential endocrine disrupting chemicals, and the Environmental Protection Agency needs to study the cumulative effect of this exposure in determining the health risk, according to a report by the National Research Council, the premier U.S. scientific organization.

Because many chemicals share the ability to mimic hormones at low levels, the EPA needs to consider how various chemicals interact and affect the body. Now, the EPA typically reviews the health risk of chemicals based on the chemical structure of each compound, rather than common health impacts of multiple chemicals.

Several phthalates are to be banned in U.S. children’s products in 2009 (though products for sale this Christmas are not subject to the ban), and Europe has gone farther by banning several phthalates used in cosmetics. For the first time, cosmetics makers will report their use of phthalates to the EPA, but it’s still virtually impossible for consumers to determine which products contain phthalates from reading ingredient labels.

Here’s how the NRC framed the need for a cumulative health assessment:

“The committee reviewed animal research and found that exposure to various phthalates in lab animals produced health outcomes, including a range of effects on the development of the male reproductive system. The most notable effects in male rats are infertility, undescended testes, malformation of the penis, and other reproductive tract malformations. However, the severity of effects differs among phthalates; some exhibit less severe or no effects. Furthermore, the age of the animals at the time of exposure is critical to the severity of the effects. For example, the fetus is most sensitive. Given that multiple human exposures to phthalates occur and that research shows exposure to different phthalates leads to similar outcomes in lab animals, a cumulative risk assessment is called for, the committee said.

“The animal studies reviewed by the committee 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.”