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Your Environment. Your Health.

Phthalate Exposure May Impair Thyroids of Young Girls

Robin Whyatt, Dr.P.H.
Columbia University Mailman School of Public Health
R01ES013543, R01ES014393, R01ES08977, P01ES09600

An NIEHS grantee and colleagues found that early childhood exposures to certain phthalates were associated with reduced thyroid function in 3-year-old girls. The study is among the first to examine the link between phthalate exposure and thyroid function in children over time.

The study included 229 inner city mothers and their children enrolled in the Mothers and Newborns Study. To assess phthalate exposure, the researchers measured metabolites produced when the body breaks down five different phthalates in urine samples from women in late pregnancy and from their children at age 3. They also assessed thyroid function by measuring the children's thyroxine (FT4) thyroid hormone and thyroid stimulating hormone at age 3 years.

The researchers found that in girls, lower levels of FT4 were associated with the presence of metabolites for di-n-butyl phthalate, di-isobutyl phthalate, butylbenzyl phthalate, and diethyl phthalate. Conversely, no associations between FT4 and child phthalate metabolites were seen in boys at age 3 years.

Previous studies have shown links between prenatal exposure to phthalates and risk for lower IQ at age 7 years, as well as mental and motor development problems in preschool children. Because thyroid hormones are necessary for normal brain development, the researchers said the new results may support the hypothesis that lower levels of thyroid hormones are involved in the association between early life phthalate exposure and neurodevelopmental problems.

Citation: Morgenstern R, Whyatt RM, Insel BJ, Calafat AM, Liu X, Rauh VA, Herbstman J, Bradwin G, Factor-Litvak P. 2017. Phthalates and thyroid function in preschool age children: Sex specific associations. Environ Int 106:11-18.

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