Summary: In utero exposure to phthalates was linked to deficits in fine motor development in females at eleven years of age.
Source: Columbia University
Scientists at the Columbia Center for Children’s Environmental Health (CCCEH) have uncovered a link between prenatal exposure to phthalates–a ubiquitous group of plasticizers and odor-enhancing chemicals–and deficits in motor function in girls. Phthalates are widely used in consumer products from plastic toys to household building materials to shampoos and are thought to disrupt endocrine function, and possibly interfere with brain development in utero.
Results of a longitudinal study of 209 New York City women and their offspring are published in the journal Environment International.
The researchers measured seven phthalate metabolites in maternal spot urine obtained during the third trimester of pregnancy. Motor function was evaluated at age 11. After adjusting for potential confounders, they saw a decrease in fine-motor functions among girls, not boys, following exposure to high levels of specific metabolites. Accounting for mixtures of phthalates and motor functions, the analysis pointed to three phthalates most linked to the deficits: mono-butyl phthalate (MBP), mono-benzyl phthalate (MBzP), and mono-isobutyl phthalate (MiBP)–none of which are metabolites of Di-2-ethylhexyl phthalates (DEHP), the most common category of phthalates.
“There a growing awareness of the problem of plastics, which are destructive to animal life and ecosystems,” says senior author Pam Factor-Litvak, PhD, professor of epidemiology.
“In this study, we have found new evidence that phthalates–chemicals commonly used in cosmetics and plastics–are harmful to children’s health. Girls with deficits in fine motor skills may have difficulty with their schoolwork, particularly related to problems writing and using electronic devices. They may also have problems with hand-eye coordination.”
Phthalates are easily unbound from plastics and released into the environment; most exposure is from diet (where they are part of food packaging), air (as they are used in air fresheners, perfumes, etc.), and skin absorption (as they are used in personal care products). Phthalates cross the blood-placenta barrier and are associated with shortened gestational age, disrupted male reproductive development, and deficits in cognitive function and behavioral outcomes.
Phthalates were previously shown to alter the levels of thyroid hormones, which are critical for brain development, especially the development of the cerebellum, which is in part accountable for coordination and fine-motor movements. Phthalates were also shown to disrupt specialized neurons associated with the development of motor skills, including fine motor skills, which are known to develop earlier in girls than in boys.
The study’s first author is Sharon Daniel of Ben-Gurion University of the Negev, Israel. Additional co-authors include A. Balalian, Robin M. Whyatt, Xinhua Liu, Virginia Rauh, and Julie Herbstman–all of Columbia Mailman School of Public Health.
Funding: The research was funded by the National Institute of Environmental Health Sciences (NIEHS) grants (ES013543, ES014393, ES08977, ES009089) and by a National Institute of Environmental Health Sciences/Environmental Protection Agency grant (ES09600/ 83214101). The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.
About this neuroscience research article
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Perinatal phthalates exposure decreases fine-motor functions in 11-year-old girls: Results from weighted Quantile sum regression
Introduction Phthalates are a group of high production chemicals, generally used as plasticizers and odor enhancers. Phthalates cross the blood-placenta barrier and are associated with deficits in cognitive functions and behavior problems in offspring. We previously reported sex-specific associations with motor function when phthalates are considered singly. Because exposure to phthalates usually occurs as mixtures, here we assess these associations between a mixture of phthalates and motor function at age 11 years.
Methods Data come from the prospective cohort study of mothers and offspring who participated in the Columbia Center for Children’s Environmental Health birth cohort (CCCEH). Seven phthalate metabolites were measured in maternal spot urine obtained during the third trimester and motor function was evaluated using the short form of the Bruininks-Oseretsky Test of Motor Proficiency, 2nd edition (BOT-2) at the age of 11 years. We used Weighted Quartile Sum (WQS) regression models to examine the effect of phthalate metabolites in males and females separately. The models were adjusted for child age in months, child BMI, maternal race (African-American vs. Dominican), prenatal alcohol consumption, maternal demoralization score, HOME score, and urine specific gravity. In a secondary analysis we used linear regression models to examine the association between the sum of molar concentrations of both DEHP and non-DEHP metabolites, and outcomes of gross and fine motor functions.
Results 209 mother-child pairs were eligible for this analysis. A significant decrease in fine-motor functions was observed among females, but not among males, following exposure to high levels of weighted quartile sum of seven phthalate metabolites (Covariates-adjusted coefficient estimate B = −2.7, 95% Confidence Interval [CI] −4.64 to −0.75, p = 0.01 for females [n = 116] and B = −1.63, 95%CI −3.94 to 0.69, p = 0.16 for males [n = 93]). The most highly weighted phthalate metabolites, associated with fine-motor functions among females, were MBP, MBZP, and MIBP, all non-DEHP phthalates.
No significant associations were found between the weighted quartile sum of seven phthalate metabolites and gross-motor functions at the age of 11 years for males (B = −0.81, 95%CI −1.17 to 1.96, p = 0.23).
With the molar sum of four non-DEHP phthalates as main predictor of linear regression models, we found significant decrease in gross and fine motor functions among females prenatally exposed to non-DEHP phthalates B = −0.98, 95%CI −1.98 to 0.03, p = 0.05 and B = −0.85, 95%CI −1.49 to −0.20, p = 0.01, respectively).
Conclusions Phthalate exposure during pregnancy was associated with decreased motor functions among 11-year-old girls.