6 June 2005
Association Between Common Chemical And Genital Development
by George Atkinson

Researchers believe they have identified an association between pregnant women's exposure to a very common class of chemicals known as phthalates and adverse effects on genital development in their male children. Phthalates are found in many plastic consumer products and a variety of cosmetics such as perfume, lotion, shampoo, make-up, nail polish, and hairspray. Often, the presence of phthalates is not noted on product labels. A prior related study found that the majority of the general population of the United States had measurable exposure to multiple phthalates. The new study appears in the journal Environmental Health Perspectives and according to the authors, is the first to "support the hypothesis that prenatal phthalate exposure at environmental levels can adversely affect male reproductive development in humans."

The authors said that previous studies focusing on phthalate prenatal exposure were in rodents whereas the current study analyzed human exposure to phthalates. The researchers collected data from mother-son pairs by analyzing urine samples for the presence of phthalate metabolites and the male children were examined for genital characteristics that serve as markers of normal sexual development. The findings suggest that some phthalates have anti-androgenic effects, that is they may suppress the hormones involved in normal male sexual development.

Higher levels of phthalate metabolites were found to correlate with a higher than expected number of abnormalities in genital development including smaller penis and scrotum and an increased likelihood of undescended testicles. These findings were consistent with those from previous rodent studies on phthalate exposure. "These changes in humans associated with prenatal exposure to some of the same phthalate metabolites that cause such alterations in male rodents suggest that these widely used phthalates may undervirilize humans as well as rodents," the researchers said.

Worryingly, the study found that the median concentration of phthalate metabolites associated with adverse male genital development was below the levels found in 25 percent of women in the United States.