A new research has revealed that prenatal exposure to elevated levels of two common chemicals found in the home, di-n-butyl phthalate (DnBP) and di-isobutyl phthalate (DiBP), are associated with substantial reductions in the IQ of children.
The study at Columbia University's Mailman School of Public Health is the first to report a link between prenatal exposure to phthalates and IQ in school-age children.
DnBP and DiBP are found in a wide variety of consumer products, from dryer sheets to vinyl fabrics to personal care products like lipstick, hairspray, and nail polish, even some soaps and since 2009, several phthalates have been banned from children's toys and other childcare articles in the United States.
However, no steps have been taken to protect the developing fetus by alerting pregnant women to potential exposures. In the U.S., phthalates are rarely listed as ingredients on products in which they are used.
Children of mothers exposed during pregnancy to the highest 25 percent of concentrations of DnBP and DiBP had IQs 6.6 and 7.6 points lower, respectively, than children of mothers exposed to the lowest 25 percent of concentrations after controlling for factors like maternal IQ, maternal education, and quality of the home environment that are known to influence child IQ scores.
Senior author Robin Whyatt said that the magnitude of these IQ differences is troubling. A six- or seven-point decline in IQ may have substantial consequences for academic achievement and occupational potential.
Lead author Pam Factor-Litvak added that while there has been some regulation to ban phthalates from toys of young children, there is no legislation governing exposure during pregnancy, which is likely the most sensitive period for brain development. Indeed, phthalates are not required to be on product labeling.
The researchers recommend that pregnant women take steps to limit exposure by not microwaving food in plastics, avoiding scented products as much as possible, including air fresheners and dryer sheets, and not using recyclable plastics labeled as 3, 6, or 7.
The study was published online in the journal PLOS ONE.