What do hairspray, nail polish, raincoats, dryer sheets, carpet backing, paint, glue, insect repellent, and heavy plastic shower curtains have in common? All of them contain chemicals called Phthalates which are widely used as plasticizers and additives in common household products. Another common denominator is children whose mothers were exposed to high level of phthalates showed lower score on IQ test at the age of seven, a new research revealed.
As part of the Columbia Center for Children's Environmental Health (CCCEH) longitudinal birth cohort study, researchers followed 328 low-income New York City women and their children and examined the link between environmental contaminants and children's health. In their latest study, researchers measured the women's exposure to four phthalates during their third trimester. Their urine was tested for di-n-butyl phthalate (DnBP), di-isobutyl phthalate (DiBP), di-2-ethylhexyl phthalate and diethyl phthalate.
And when their children reached the age of seven, the children were given IQ tests.
The children of mothers who had the highest level of exposure to two of the phthalates had IQ levels between six and eight points lower than those in the lower 25th percentile of exposure.
"This is the only study looking at this in a longitudinal fashion," said lead author Pam Factor-Litvak, a professor at Columbia University's Mailman School of Public Health in New York. "I think that there would need to be more studies to build up causation," according to Factor-Litvak who said that the study only observed a relationship and did not test cause and effect.
"I think we were quite surprised, not about the IQ results but by how large the disparity was," she added.
Phthalates have been shown to disrupt the endocrine system, including testosterone and thyroid hormone levels.
The difference showed when the authors accounted for other factors that could influence IQ, including the mother's IQ, alcohol use during pregnancy, education, marital status and the child's birth weight.
"With observational studies, there is always the chance that the results may be in part explained by an unmeasured factor that we haven't yet considered," said Stephanie Engel, associate professor of epidemiology at UNC Gillings School of Global Public Health in Chapel Hill, North Carolina.
"I would characterize this study as thorough and high quality, and the results concerning," said Engel. "But there needs to be more research in this area before firm conclusions can be drawn."
"It is clear that there needs to be a serious discussion in the scientific and policy communities about whether the evidence is strong enough yet to warrant widespread policy changes, not just on the basis of this study, but also including a range of childhood health outcomes that have already been reported in the literature," Engel said.
Phthalate exposure can occur through the skin, breathing and ingestion. While six types of phthalates are currently banned from children's toys, according to the U.S. Consumer Product Safety Commission; the Food and Drug Administration currently does not have evidence that phthalates as used in cosmetics pose a safety risk.
The researchers advised that to minimize contact with the chemical, the against microwaving food in plastic and not to use scented products, including air fresheners, cleaning supplies and personal care products.They also advised against the use of plastics #3, 6 and 7, and recommended storing food in glass containers instead of plastic as much as possible.
