The Association between Exposure to a Flame-retardant Chemical and Autoimmune Disorders Open Access

Abstract

The Association between Exposure to a Flame-retardant Chemical and Autoimmune Disorders

By Sarah Mardovich

Background: Polybrominated Biphenyls (PBBs) are synthetic halogenated compounds that were originally used as flame retardants. In 1973, individuals living in Michigan were exposed to PBBs through the consumption of contaminated meat and dairy products after an accidental substitution of a flame retardant containing PBB for animal feed. Previous studies on this cohort suggest that exposure to PBBs may be related to many health conditions. However, no studies have evaluated whether exposure to PBBs is associated with autoimmune disease. In this cross-sectional study, we evaluated this possibility and whether this association differs by sex and age at exposure.

Methods: Current serum PBB levels were natural log transformed and evaluated for their association with self-reported autoimmune disease. Logistic regression was performed to evaluate models stratified by sex and age at exposure. Potential confounders included sex, age at blood draw, BMI, and smoking status. All statistical analyses were conducted in SAS version 9.4 and p-values less than 0.05 were considered significant.

Results: Overall, current serum PBBs were not associated with lifetime prevalence of autoimmune disease. However, among 228 individuals exposed to PBBs in utero, women were over four times as likely to have an autoimmune disease compared to men after controlling for age at blood draw (OR=4.234 [1.872, 9.580]). In addition, increasing PBB was associated with a reduced risk of autoimmune disease and that association varied in magnitude, depending on the age at blood draw. Among 340 individuals exposed to PBBs as children, women were twice as likely to have an autoimmune disease compared to men (OR=2.167[1.245-3.772]]). Among 284 individuals exposed to PBBs as adults, women were nearly twice as likely to have an autoimmune disease compared to men (OR=1.911 [1.047, 3.490]). These results were statistically significant.

Conclusions: Exposure to PBBs was not significantly associated with autoimmune disease in the study population. Among those exposed in utero, the association between PBBs and autoimmune disease differed by age at blood draw. Exposed women were significantly more likely to have autoimmune disease than men. The magnitude of the effect of participant sex differed by whether participants were exposed in utero, as children, or as adults. 

Table of Contents

Chapter I: Literature Review.....................................................................1

Chapter II: Manuscript.............................................................................9

Abstract..................................................................................................9

Introduction............................................................................................10

Methods..................................................................................................12

Results....................................................................................................16

Discussion...............................................................................................20

Chapter III: Extended Conclusions............................................................25

Strengths and Limitations........................................................................25

Public Health Implications.......................................................................27

Future Directions....................................................................................27

References..............................................................................................29

Tables....................................................................................................35 

About this Master's Thesis

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School	Rollins School of Public Health
Department	Epidemiology
Subfield / Discipline	Epidemiology - MPH & MSPH
Degree	M.P.H.
Submission	Master's Thesis
Language	English
Research Field	Health Sciences, Public Health Environmental Health Health Sciences, Epidemiology
Keyword	Autoimmune Disease Polybrominated Biphenyls Sex Age at Exposure Endocrine Disrupter
Committee Chair / Thesis Advisor	Dr. Michele Marcus, Emory University

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