A new study led by Mount Sinai researchers in collaboration with scientists from Cornell University and the U.S. Centers for Disease Control and Prevention has found higher prenatal exposure to phthalates, man-made chemicals that interfere with hormonal messaging, to be connected with disruptive and problem behaviors in children between the ages of 4 and 9.
The study, the first to examine the effects of prenatal phthalate exposure on child neurobehavioral development, appears on the Environmental Health Perspectives Web site.

"There is increasing evidence that phthalate exposure is harmful to children at all stages of development," said Stephanie Engel, Ph.D., lead study author and associate professor of preventive medicine at Mount Sinai School of Medicine. "We found a striking pattern of associations between low molecular weight phthalates, which are commonly found in personal care products, and disruptive childhood behaviors, such as aggressiveness and other conduct issues, and problems with attention. These same behavioral problems are commonly found in children diagnosed with attention deficit hyperactivity disorder (ADHD), oppositional defiant disorder or conduct disorder."

Phthalates are part of a group of chemicals known as endocrine disruptors, which interfere with the body's endocrine (hormone) system. They are a family of compounds found in a range of consumer products, including in nail polishes to increase their durability and reduce chips, as well as in cosmetics, perfumes, lotions and shampoos to carry fragrance. Other phthalates are used to increase the flexibility and durability of plastics such as PVC, and they're also included as time-release coatings on medications and nutritional supplements.

"Recently, the government instituted regulations limiting certain phthalates in things like child care articles or toys that a young child might put in [his or her] mouth," continued Dr. Engel. "But it's [a] mother's contact with phthalate-containing products that causes prenatal exposure. The phthalates that we found most strongly related to neurodevelopment were those commonly found in cosmetics, perfumes, lotions and shampoos. Current U.S. regulations do not address these kinds of phthalates."

For the study, phthalate metabolite levels were analyzed in prenatal urine samples of a multiethnic group of 404 women who were pregnant for the first time. The women were invited to participate in follow-up interviews when their children were between the ages of 4 and 9. The mothers were not informed of their phthalate metabolite levels, and the researchers were unaware of their exposures when testing the children.

Follow-up visits were completed by 188 of the women and their children. At each follow-up visit, the mothers completed validated questionnaires designed to assess their behavior and executive functions. The researchers found mothers with higher concentrations of low molecular weight phthalates consistently reported poorer behavioral profiles in their children. The strongest trends were in the categories of conduct and externalizing problems, characteristics typically associated with oppositional defiant disorder, conduct disorder and ADHD.

"These are high-level, chronic exposures that start before the child is even born but continue throughout [the child's] life. More research is needed to examine the effects of cumulative exposure to phthalates on child development. But what this study suggests is that it's not enough to regulate childhood exposure to these chemicals. The regulations need to include products that moms use," said Dr. Engel.

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