POLYBROMINATED DIPHENYL ETHERS (PBDEs) AND ADVERSE PREGNANCY OUTCOMES: A SYSTEMATIC REVIEW

Begum M¹, Kumarathasan P^1,2, Gomes J¹

¹ Interdisciplinary School of Health Sciences, Faculty of Health Sciences, University of Ottawa, Ottawa, ON, Canada ²Environmental Health Science and Research Bureau, HECS, Health Canada, Ottawa, ON, Canada.

Background: Polybrominated diphenyl ethers (PBDEs) are flame retardants and considered as persistent organic pollutants (POPs) found in the environment. PBDE congeners are measured in animals and humans, thus raising environmental and human health concerns. There are reports on PBDEs having endocrine disrupting properties, yet, studies on the effects of PBDEs on vulnerable population such as pregnant mothers and infants are limited, and related toxicity mechanisms are unclear.

 Objective: The objective of this study was to examine the relationship between PBDE levels in mothers during pregnancy and adverse maternal/infant health outcomes. PBDE exposure-related changes in maternal biomarker levels as intermediary outcomes was also of interest for this work.

Methods: The literature review was conducted using four electronic databases: PubMed, Scopus, Embase and Web of Science. The search strategy included search terms (polybrominated diphenyl ether*), (gestational* OR pregnan* OR maternal*), AND (infant* OR newborn* OR neonate*) and published articles between January 2005 and February 2022. Quality was assessed with the Newcastle-Ottawa Scale.

Results & Discussion: A total of 54 human observational studies were included in the study. A second reviewer examined the validity of these articles. This systematic review reports on the association between maternal PBDE and gestational hypertension/preeclampsia (N=2) and gestational diabetes mellitus/glycemic index (N=6) as maternal health outcomes. Similarly, there were reports on PBDE and infant outcomes including infant birth weight, birth length and cephalic perimeter (N=22) as well as articles on preterm birth, fetal growth restriction and APGAR scores (N=8).  Although, findings on PBDE exposure and adverse infant outcomes showed some inconsistencies, many studies found a negative correlation between maternal PBDEs and infant birth weight, birth length and cephalic perimeter, sometimes when stratified by sex. Association between maternal PBDE levels and maternal biomarker changes were reported in few studies, notably the negative impact of exposure on markers of thyroid function an inflammatory endpoint.

Conclusion: The results from this review identified associations between maternal PBDE levels and adverse maternal/infant health outcomes, and maternal biomarkers. Findings from this work imply necessity of further research to validate PBDE exposure-related adverse maternal/infant health effects supported by mechanistic understanding.