A November publication released by Environmental Research and authored by Project 1 trainee Amira Aker and multiple researchers revealed interesting findings on the relation contaminants such as phenols and parabens have on hormone changes during pregnancy. Researchers twice measured phenol/paraben biomarkers of 106 child-bearing participants during their pregnancies. Exposures to certain contaminants were found to be associated with changes in reproductive/thyroid hormone levels, changes that differed depending upon the period of pregnancy measurements were taken. These changes may contribute to adverse health effects in mothers or their offspring, but additional research is required.
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Title: Phenols and parabens in relation to reproductive and thyroid hormones in pregnant women
Journal: Environmental Research
Publisher: Elsevier
Date: November 2016
PROTECT Team Members Involved:
Amira M. Aker, Deborah J. Watkins, Lauren E. Johns, Kelly K. Ferguson, Liza V. Anzalota Del Toro, Akram N. Alshawabkeh, José F. Cordero, John D. Meeker
Other Contributor(s): Offie P. Soldin
Abstract
Introduction
Phenols and parabens are ubiquitous environmental contaminants. Evidence from animal studies and limited human data suggest they may be endocrine disruptors. In the current study, we examined associations of phenols and parabens with reproductive and thyroid hormones in 106 pregnant women recruited for the prospective cohort, “Puerto Rico Testsite for Exploring Contamination Threats (PROTECT)”.
Methods
Urinary exposure biomarkers (bisphenol A, triclosan, benzophenone-3, 2,4-dichlorophenol, 2,5-dichlorophenol, butyl, methyl and propyl paraben) and serum hormone levels (estradiol, progesterone, sex hormone-binding globulin (SHBG), free triiodothyronine (FT3), free thyroxine (FT4) and thyroid stimulating hormone) were measured at up to two time points during pregnancy (16–20 weeks and 24–28 weeks). We used linear mixed models to assess relationships between exposure biomarkers and hormone levels across pregnancy, controlling for urinary specific gravity, maternal age, BMI and education. In sensitivity analyses, we evaluated cross-sectional relationships between exposure and hormone levels stratified by study visit using linear regression.
Results
An IQR increase in methyl paraben was associated with a 7.70% increase (95% CI 1.50, 13.90) in SHBG. Furthermore, an IQR increase in butyl paraben as associated with an 8.46% decrease (95% CI 16.92, 0.00) in estradiol, as well as a 9.34% decrease (95% CI −18.31,−0.38) in estradiol/progesterone. Conversely, an IQR increase in butyl paraben was associated with a 5.64% increase (95% CI 1.26, 10.02) in FT4. Progesterone was consistently negatively associated with phenols, but none reached statistical significance. After stratification, methyl and propyl paraben were suggestively negatively associated with estradiol at the first time point (16–20 weeks), and suggestively positively associated with estradiol at the second time point (24–28 weeks).
Conclusions
Within this ongoing birth cohort, certain phenols and parabens were associated with altered reproductive and thyroid hormone levels during pregnancy. These changes may contribute to adverse health effects in mothers or their offspring, but additional research is required.