Arash Derakhshan1, Eva Tanner2, Marlene Stratmann3, Huan Shu3, Barbara Demeneix4, Chris Gennings4, Robin Peeters5, Carl-Gustaf Bornehag5, Tim Korevaar6
(1) Erasmus MC, Rotterdam, Netherlands. (2) Department of Environmental Medicine and Public Health, Icahn School of Medicine at Mount Sinai, NYC, US. (3) Faculty of Health, Department of Health Sciences, Karlstad University, Karlstad, Sweden. (4) CNRS, Muséum National d’Histoire Naturelle, Paris, France. (5) Erasmus MC, Rotterdam, Netherlands. (6) Erasmus MC, Rotterdam, Netherlands.
Background:
Based on experimental and human studies endocrine disrupting chemicals (EDCs) can disrupt the thyroid system. However, it is still unclear how a mixture of EDCs is associated with thyroid function in pregnant women.
Methods:
We used data of 1970 pregnant women from the Swedish Environmental Longitudinal Mother and Child, Asthma and Allergy (SELMA) study to investigate the cross-sectional association between exposure for 26 chemical compounds with maternal thyroid system (TSH, FT4, TT4, FT3, TT3, as well as FT4/FT3 and TT4/TT3 ratios) in early pregnancy, using Weighted Quantile Sum (WQS) regression.
Results:
Higher exposure to EDCs mixture was associated with a lower FT3 [WQS Estimate per an IQR increase (95% CI): -0.09 (-0.16 to -0.01), mostly driven by PCBs] and a lower TT3 [WQS Estimate per an IQR increase (95% CI): -0.05 (-0.09 to -0.01), mostly driven by PFOS]. In addition, higher exposure to a mixture of short lived urinary based compounds (such as phenols and phthalates) was associated with a lower TT4/TT3 ratio while exposure to a mixture of persistent serum-based compounds (such as PFAS) was associated with a higher TT4/TT3 ratio.
Conclusion:
In this proof-of-principle analysis we show that there could be an added benefit of analyzing thyroid disrupting EDCs using a mixture-based analysis approach. Our findings provide hypotheses for future experimental and human studies to investigate the effects of EDCs as a mixture on thyroid system.