Associations between Organophosphate Flame Retardant Exposure during Pregnancy and Reproductive and Thyroid Hormone Levels: A Preliminary Analysis

摘要

The use of organophosphate flame retardants (PFRs) in consumer products has increased in recent years due to the phase out of polybrominated diphenyl ethers. As a result, exposure to PFRs is widespread, with uncertain impacts on health. A previous study of pregnant women undergoing in vitro fertilization found that higher urinary PFR metabolites were associated with decreased treatment success, while another reported associations between a PFR and increased thyroid hormone in women. Therefore, we aimed to investigate relationships between PFR exposure and serum hormone levels among a subset of pregnant women enrolled in the Puerto Rico Testsite for Exploring Contamination Threats (PROTECT) birth cohort (n=148). We measured 7 PFR metabolites (bis-2chloroethyl phosphate (BCEtP), bis-(l-chloro-2propl) phosphate (BCPP), bis(l,3-dichloro- 2-propyl) phosphate (BDCPP), di-n- butyl phosphate (DNBP), di-benzyl phosphate (DBzP), di-cresyl phosphate (DCP) and diphenyl phosphate (DPHP)) in urine samples collected at 16-20 and 24-28 weeks gestation. Testosterone (T), estradiol (E2), estriol (E3), progesterone, corticotropin-releasing hormone (CRH), sex hormone binding globulin (SHBG), thyroid stimulating hormone (TSH), T4, T3, and free T4 (fT4) were measured in serum samples collected at the same time points. We used linear mixed models to assess relationships between PFRs and hormone levels across pregnancy, adjusting for age, pre-pregnancy BMI, and specific gravity. DNBP, DBzP, and DCP were detected in <50% of samples. BCEtP was associated with higher SHBG, while BDCPP was associated with higher T, E2, and fT4. BCPP was associated with lower E2, and DPHP was associated with lower T4. These preliminary findings suggest that PFRs may disrupt hormone levels during pregnancy. Further research into endocrine disruption as a mechanism by which PFR exposure during pregnancy may affect pregnancy and birth outcomes, as well as fetal and child development, is necessary.