Birth Outcomes Associated with Paternal Polybrominated and Polychlorinated Biphenyl Exposure

Abstract

BACKGROUND AND AIM: In 1973, polybrominated biphenyl (PBB) flame retardant was shipped to Michigan feed mills in place of a nutritional supplement and contaminated the food supply. Following the accident, the Michigan PBB Registry was established to study the long-term health effects of halogenated compounds, and is now led by a community-academic partnership. PBB exposure is associated with decreased DNA methylation in sperm regulatory elements controlling imprinted genes, which may lead to adverse birth outcomes in children whose fathers have increased levels of serum PBB or polychlorinated biphenyl (PCB), an analogue of PBB. To further understand the impact of paternal exposures on children, we analyzed paternal PBB and PCB levels and premature birth and low birthweight. METHODS: We investigated the outcomes of birthweight and gestational age of offspring whose fathers enrolled in the PBB Registry and provided serum to measure PBB and PCB concentrations. Birth outcomes were determined by linking paternal PBB records to the Michigan vital records. Birthweight and gestational age were dichotomized at the 25th percentile and 37 weeks respectively, and paternal PBB and PCB levels were divided into tertiles. Offspring birthweight and gestational age were modeled against paternal PBB and PCB serum concentrations using log-risk regression, adjusting for clustering, paternal health and lifestyle factors, and offspring sex. RESULTS:Elevated PBB and PCB levels are associated with an increased risk of low offspring birthweight, but not preterm birth. Fathers in the middle and upper PBB and PCB tertiles illustrated increased risk ratios (RR) for low offspring birthweight, RR=1.42 (CI=0.93-2.17) and RR=1.47 (CI=1.03-2.10) for PBB, and RR=1.73 (CI=1.12-2.67) and RR=1.42 (CI=0.84-2.41) for PCB respectively. Elevated PBB and PCB levels illustrated no significant increased risk for preterm birth in the middle and upper tertiles. CONCLUSIONS:These findings suggest increased paternal PBB and PCB levels may negatively impact offspring birthweight. KEYWORDS: Endocrine disrupting chemicals, Birth outcomes, Children's environmental health, Community outreach, Environmental epidemiology