A new study has found that prenatal exposure to phthalates may have a significant negative impact on children’s IQ levels by age 7. Women who were exposed to the highest levels of two common household chemicals – di-n-butyl phthalate (DnBP) and di-isobutyl phthalate (DiBP) – during pregnancy had children whose IQ scores measured 6 points lower on average than those women whose exposure was reduced.
Researchers followed 328 inner-city mothers and their children who were born between 1998 and 2006. Urine samples were taken during the last trimester of pregnancy to measure phthalate content, and the children were followed up with interviews and testing at ages 3, 5, and 7.
The measurement for child IQ was based on four areas of mental functioning – the Verbal Comprehension Index, the Perceptual Reasoning Index, the Working Memory Index, and the Processing Speed Index. Researchers controlled for factors such as maternal IQ and education levels, and quality of the home environment, which are known to affect child IQ levels.
Researchers found that the 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.
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