Pregnancy exposure to common-detect organophosphate esters and phthalates and maternal thyroid function

Area of Science:

• Environmental Health
• Endocrinology
• Toxicology

Background:

• Human populations face increasing exposure to organophosphate esters (OPEs) and phthalates.
• Some metabolites are linked to altered thyroid function, but research on OPEs, especially during pregnancy, is limited.
• Thyroid function is critical for maternal and fetal health during gestation.

Purpose of the Study:

• To investigate the relationship between OPEs and phthalates exposure and maternal thyroid function during pregnancy.
• To characterize associations using a cross-sectional study within the Norwegian Mother, Father, and Child Cohort (MoBa).

Main Methods:

• Included 473 euthyroid pregnant women at 17 weeks' gestation.
• Measured four OPE and six phthalate metabolites in urine and six thyroid function biomarkers in blood.
• Employed co-pollutant adjusted general linear models (GLM) and Bayesian Kernel Machine Regression (BKMR) to analyze relationships, accounting for co-exposures.

Main Results:

• Analysis focused on diphenyl phosphate (DPHP), di-n-butyl phosphate (DNBP), and all phthalate metabolites.
• Higher summed di-isononyl phthalate metabolites (∑DiNP) were associated with a lower total triiodothyronine to total thyroxine ratio in GLM.
• DNBP showed similar trends, DPHP and other phthalates showed inverse associations; BKMR generally attenuated GLM findings, except for ∑DiNP and the TT3:TT4 ratio.

Conclusions:

• Maternal thyroid function demonstrated modest variation with ∑DiNP exposure.
• Observed associations for DPHP differed based on the statistical model used.
• Findings highlight potential endocrine-disrupting effects of OPEs and phthalates on maternal thyroid health.