A new study has found that exposure to phthalates, chemicals used in perfumes, nail varnish and plastics, at the prenatal stage can affect development and behavior in children.

Phthalates are part of a group of chemicals known as endocrine disruptors, that interfere with the body's endocrine, or hormone system. They are a family of compounds found in a wide range of consumer products such as nail polishes, to increase their durability and reduce chips, and in cosmetics, perfumes, lotions and shampoos, to carry fragrance. Other phthalates are used to increase the flexibility and durability of plastics such as PVC, or included as coatings on medications or nutritional supplements to make them timed-release.

There are regulations limiting certain phthalates in things like child care articles or toys that a young child might put in their mouth. But the new study (led by Mount Sinai researchers in collaboration with scientists from Cornell University and the U.S. Centers for Disease Control and Prevention) concludes that it's their mother's contact with phthalate-containing products that causes prenatal exposure. The phthalates that they found most strongly related to neurodevelopment were those commonly found in cosmetics, perfumes, lotions and shampoos. Current US regulations do not address these kinds of phthalates.

Phthalates is cosmetics appear under the names of dibutylphthalate (DBP), dimethylphthalate (DMP), and diethylphthalate (DEP). They are used primarily at concentrations of less than 10%. These days, many cosmetic companies have been phasing out phthalates and it is becoming more and more common to see nail polish proclaiming itself to be phthalates free.

Nonetheless, Proctor & Gamble uses diethyl phthalate (DEP) and dimethyl phthalate (DMP).  It argues on its website that "phthalates are a broad class of ingredients and each has its own benefit and safety profile. Contrary to groups that attempt to characterize all phthalates as unsafe, each type must be evaluated for safety separately based upon its own unique profile. For example, mushrooms are a family in nature that has species that are safe and tasty to eat (such as portobello), but also has other species that can cause significant safety concerns if consumed in sufficient amounts."

The mushroom argument may not hold much water for the scientists on this latest study. The lead scientist on the Mont Sinai study, Stephanie Engel has called for new regulations: "These are high level, chronic exposures that start before the child is even born, but continue throughout their 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.

The study took urine samples from 177 women who were enrolled for prenatal care either at the Mount Sinai Diagnostic Treatment Center or at two private practices on the Upper East Side of Manhatten. These  samples (which were taken between 25 and 40 weeks into the pregnancy) were analysed for ten phthalate metabolites that were divided into two groups, high molecular weight and low molecular weight, to limit the number of statistical tests performed. The researchers found that mothers with higher concentrations of low molecular weight phthalates consistently reported poorer behavioral profiles in their children.