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Maternal urinary phthalate metabolites during pregnancy and thyroid hormone concentrations in maternal and cord sera: The HOME Study.
Int J Hyg Environ Health. 2018 05; 221(4):623-631.IJ

Abstract

BACKGROUND

Phthalates, endocrine-disrupting chemicals that are commonly found in consumer products, may adversely affect thyroid hormones, but findings from prior epidemiologic studies are inconsistent.

OBJECTIVES

In a prospective cohort study, we investigated whether maternal urinary phthalate metabolite concentrations and phthalate mixtures measured during pregnancy were associated with thyroid hormones among pregnant women and newborns.

METHODS

We measured nine phthalate metabolites [monoethyl phthalate (MEP), mono-n-butyl phthalate, mono-isobutyl phthalate, monobenzyl phthalate (MBzP), and four monoesthers of di(2-ethylhexyl) phthalate] in urine collected at approximately 16 and 26 weeks' gestation among women in the Health Outcomes and Measures of the Environment Study (2003-2006, Cincinnati, Ohio). Thyroid stimulating hormone (TSH) and free and total thyroxine and triiodothyronine were measured in maternal serum at 16 weeks' gestation (n = 202) and cord serum at delivery (n = 276). We used multivariable linear regression to assess associations between individual urinary phthalate metabolites and concentrations of maternal or cord serum thyroid hormones. We used weighted quantile sum regression (WQS) to create a phthalate index describing combined concentrations of phthalate metabolites and to investigate associations of the phthalate index with individual thyroid hormones.

RESULTS

With each 10-fold increase in 16-week maternal urinary MEP, maternal serum total thyroxine (TT4) decreased by 0.52 μg/dL (95% CI: -1.01, -0.03). For each 10-fold increase in average (16- and 26-week) maternal urinary MBzP, cord serum TSH decreased by 19% (95% CI: -33.1, -1.9). Among mothers, the phthalate index was inversely associated with maternal serum TT4 (WQS beta = -0.60; 95% CI: -1.01, -0.18). Among newborns, the phthalate index was inversely associated with both cord serum TSH (WQS beta = -0.11; 95% CI: -0.20, -0.03) and TT4 (WQS beta = -0.53; 95% CI: -0.90, -0.16).

CONCLUSION

Our results suggest that co-exposure to multiple phthalates was inversely associated with certain thyroid hormones (TT4 in pregnant women and newborns, and TSH in newborns) in this birth cohort. These findings highlight the need to study chemical mixtures in environmental epidemiology.

Authors+Show Affiliations

Department of Epidemiology, Geisel School of Medicine at Dartmouth, Lebanon, NH, USA; Department of Epidemiology, Brown University School of Public Health, Providence, RI, USA. Electronic address: Megan.E.Romano@Dartmouth.edu.Department of Epidemiology, Brown University School of Public Health, Providence, RI, USA.Department of Biology, University of Massachusetts, Amherst, MA, USA.Department of Laboratory Medicine, University of Washington, Seattle, WA, USA.Division of Laboratory Sciences, National Center for Environmental Health, Centers for Disease Control and Prevention, Atlanta, GA, USA.Department of Epidemiology, Geisel School of Medicine at Dartmouth, Lebanon, NH, USA.Division of General and Community Pediatrics, Department of Pediatrics, Cincinnati Children's Hospital Medical Center, Cincinnati, OH, USA.Epidemiology and Biostatistics, Department of Environmental Health, University of Cincinnati College of Medicine, Cincinnati, OH, USA.Child and Family Research Institute, BC Children's and Women's Hospital and Faculty of Health Sciences, Simon Fraser University, Vancouver, British Columbia, Canada.Department of Epidemiology, Brown University School of Public Health, Providence, RI, USA.

Pub Type(s)

Journal Article
Research Support, N.I.H., Extramural
Research Support, U.S. Gov't, Non-P.H.S.

Language

eng

PubMed ID

29606598

Citation

Romano, Megan E., et al. "Maternal Urinary Phthalate Metabolites During Pregnancy and Thyroid Hormone Concentrations in Maternal and Cord Sera: the HOME Study." International Journal of Hygiene and Environmental Health, vol. 221, no. 4, 2018, pp. 623-631.
Romano ME, Eliot MN, Zoeller RT, et al. Maternal urinary phthalate metabolites during pregnancy and thyroid hormone concentrations in maternal and cord sera: The HOME Study. Int J Hyg Environ Health. 2018;221(4):623-631.
Romano, M. E., Eliot, M. N., Zoeller, R. T., Hoofnagle, A. N., Calafat, A. M., Karagas, M. R., Yolton, K., Chen, A., Lanphear, B. P., & Braun, J. M. (2018). Maternal urinary phthalate metabolites during pregnancy and thyroid hormone concentrations in maternal and cord sera: The HOME Study. International Journal of Hygiene and Environmental Health, 221(4), 623-631. https://doi.org/10.1016/j.ijheh.2018.03.010
Romano ME, et al. Maternal Urinary Phthalate Metabolites During Pregnancy and Thyroid Hormone Concentrations in Maternal and Cord Sera: the HOME Study. Int J Hyg Environ Health. 2018;221(4):623-631. PubMed PMID: 29606598.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Maternal urinary phthalate metabolites during pregnancy and thyroid hormone concentrations in maternal and cord sera: The HOME Study. AU - Romano,Megan E, AU - Eliot,Melissa N, AU - Zoeller,R Thomas, AU - Hoofnagle,Andrew N, AU - Calafat,Antonia M, AU - Karagas,Margaret R, AU - Yolton,Kimberly, AU - Chen,Aimin, AU - Lanphear,Bruce P, AU - Braun,Joseph M, Y1 - 2018/03/23/ PY - 2017/12/03/received PY - 2018/03/21/revised PY - 2018/03/22/accepted PY - 2018/4/3/pubmed PY - 2019/2/1/medline PY - 2018/4/3/entrez KW - Phthalates KW - Pregnancy KW - Thyroid hormones KW - Weighted quantile sum regression SP - 623 EP - 631 JF - International journal of hygiene and environmental health JO - Int J Hyg Environ Health VL - 221 IS - 4 N2 - BACKGROUND: Phthalates, endocrine-disrupting chemicals that are commonly found in consumer products, may adversely affect thyroid hormones, but findings from prior epidemiologic studies are inconsistent. OBJECTIVES: In a prospective cohort study, we investigated whether maternal urinary phthalate metabolite concentrations and phthalate mixtures measured during pregnancy were associated with thyroid hormones among pregnant women and newborns. METHODS: We measured nine phthalate metabolites [monoethyl phthalate (MEP), mono-n-butyl phthalate, mono-isobutyl phthalate, monobenzyl phthalate (MBzP), and four monoesthers of di(2-ethylhexyl) phthalate] in urine collected at approximately 16 and 26 weeks' gestation among women in the Health Outcomes and Measures of the Environment Study (2003-2006, Cincinnati, Ohio). Thyroid stimulating hormone (TSH) and free and total thyroxine and triiodothyronine were measured in maternal serum at 16 weeks' gestation (n = 202) and cord serum at delivery (n = 276). We used multivariable linear regression to assess associations between individual urinary phthalate metabolites and concentrations of maternal or cord serum thyroid hormones. We used weighted quantile sum regression (WQS) to create a phthalate index describing combined concentrations of phthalate metabolites and to investigate associations of the phthalate index with individual thyroid hormones. RESULTS: With each 10-fold increase in 16-week maternal urinary MEP, maternal serum total thyroxine (TT4) decreased by 0.52 μg/dL (95% CI: -1.01, -0.03). For each 10-fold increase in average (16- and 26-week) maternal urinary MBzP, cord serum TSH decreased by 19% (95% CI: -33.1, -1.9). Among mothers, the phthalate index was inversely associated with maternal serum TT4 (WQS beta = -0.60; 95% CI: -1.01, -0.18). Among newborns, the phthalate index was inversely associated with both cord serum TSH (WQS beta = -0.11; 95% CI: -0.20, -0.03) and TT4 (WQS beta = -0.53; 95% CI: -0.90, -0.16). CONCLUSION: Our results suggest that co-exposure to multiple phthalates was inversely associated with certain thyroid hormones (TT4 in pregnant women and newborns, and TSH in newborns) in this birth cohort. These findings highlight the need to study chemical mixtures in environmental epidemiology. SN - 1618-131X UR - https://www.unboundmedicine.com/medline/citation/29606598/Maternal_urinary_phthalate_metabolites_during_pregnancy_and_thyroid_hormone_concentrations_in_maternal_and_cord_sera:_The_HOME_Study_ L2 - https://linkinghub.elsevier.com/retrieve/pii/S1438-4639(17)30823-4 DB - PRIME DP - Unbound Medicine ER -