Prenatal exposure to common chemicals linked with drop in child IQ

Following a previous study linking higher maternal levels of two common chemicals with slower mental and motor development in preschoolers, a new study has found that this effect continues into school age.

The study involved 328 inner-city mothers and their children. The mothers' levels of prenatal urinary metabolites of di-n-butyl phthalate (DnBP), butylbenzyl phthalate (BBzP), di-isobutyl phthalate (DiBP), di-2-ethylhexyl phthalate and diethyl phthalate were measured in late pregnancy. IQ tests were given to the children at age 7.

Children's IQ scores were negatively associated with higher maternal phthalate levels. Among children of mothers with the highest versus lowest levels of DnBP and DiBP metabolite concentrations (the top 25% vs the bottom 25%), IQ was 6.7 and 7.6 points lower, respectively. There were similar associations with processing speed, perceptual reasoning and working memory; DiBP and verbal comprehension; BBzP and perceptual reasoning.

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. Since 2009, several phthalates have been banned from children's toys and other childcare articles in the United States.

Although the results are correlational, and don't prove that phthalates are responsible, the researchers recommend that pregnant women avoid storing or microwaving food in plastic containers, and avoid scented cleaning and personal care products (phthalates hold scent). They are also advised not to use plastics labeled 3, 6, or 7.

Factors such as maternal IQ, maternal education, and quality of the home environment, were controlled for in the analysis. The range of phthalate metabolite levels measured in the mothers was not unusual.

[3841] Factor-Litvak, P., Insel B., Calafat A. M., Liu X., Perera F., Rauh V. A., et al.
(2014).  Persistent Associations between Maternal Prenatal Exposure to Phthalates on Child IQ at Age 7 Years.
PLoS ONE. 9(12),