Abstracts: ISEE 21st Annual Conference, Dublin, Ireland, August 25-29, 2009: Symposium Abstracts
Background and Objective:
Prenatal phthalate exposure has been shown to affect thyroid and sex hormone metabolism. These findings suggest the possibility that phthalates may also interfere with hormone-sensitive aspects of neurodevelopment. Both fetal testosterone levels and thyroid hormone have been implicated in the etiology of autism spectrum disorders (ASD). We investigated the association between prenatal phthalate exposure and subclinical austitic symptomatology in a prospective birth cohort.
The Mount Sinai Children’s Environmental Health Study enrolled a multiethnic prenatal population from 1998–2002 (n = 404). Third trimester urines were analyzed for phthalate metabolites, which were grouped by molecular weight into monoester metabolites of high (>250 Daltons) molecular weight (HMW) and low (<250 Daltons) molecular weight (LMW). At the 8 year visit, mothers (n = 153) completed the Social Responsiveness Scale (SRS), a questionnaire designed to identify characteristics of ASD, including problems with interpersonal behavior, communication, and repetitive/stereotypic behaviors. The SRS is validated for use in the general population.
In adjusted generalized linear models, increased log-LMW concentrations were associated with poorer SRS scores (B = 1.53, 95% CI 0.26–2.80, P-value: 0.02). SRS treatment subscale scores were also significantly poorer for cognition (B = 1.43, P = .03), communication (B = 1.80, P = .01) and awareness (B = 1.29, P = .03), but not for Mannerisms or Motivation. There were no associations for HMW phthalates, which have lower exposure levels.
Prenatal phthalate exposure was associated with evidence of social impairment in a healthy, urban population. Impaired social functioning is a prominent feature of multiple behavior and developmental disorders, including autism spectrum disorders. These results extend our previous finding of abnormalities in neonatal behavior in relation to prenatal phthalate exposure. Our study was limited by a small sample size and substantial attrition between birth and follow-up.