Brominated flame retardants and legacy organochlorines in archived human placenta samples: Sex differences, temporal analysis and associations with infant birth weight

Abstract

Perinatal exposure to persistent organic pollutants (POPs) has been suggested to play a role in the etiology of adverse pregnancy outcomes. This study evaluated temporal changes in the accumulation of several classes of POPs, including polybrominated diphenyl ethers (PBDEs), polychlorinated biphenyls (PCBs) and several organochlorine pesticides in human placenta and examined their associations with birth outcomes at delivery. Placental tissues (n = 99) previously collected and archived at the Duke University Medical Center from 2009 to 2015 were analyzed for 22 POPs using gas chromatography mass spectrometry. The mean age of mothers was 30.6 years; 8% of newborns were characterized as low birthweight (<2500 g). Of the 22 POPs targeted in the analysis, only p,p'-DDE, BDE-47 and BDE-100 were detected in more than 50% of the samples, with median concentrations of 0.110, 0.310, and 0.033 ng/g wet weight, respectively. Placental PBDE concentrations generally decreased over time, particularly BDE-47. Placental tissues associated with female infants had significantly higher levels of BDE-100 than placental tissues associated with male infants (p = 0.02) and a similar, but not statistically significant trend was observed for BDE-47 (p = 0.07). Multivariate regression models revealed that placental BDE-47 concentrations were associated with a significantly lower birthweight among male, but not female infants. A similar, although non-statistically significant, trend was observed for other POPs, further suggesting sex-specific associations between gestational exposure to POPs and birthweight.

Keywords: Birth outcomes; DDT; Flame retardants; PBDE; Placenta.

Figure 1.

Sex-stratified POP concentrations (ng/g ww) in placental tissue. (* indicates significantly higher levels of BDE-100 in placentas from females (n=53) relative to males (n=46); Kruskal-Wallis Tests, p=0.02).

Figure 2:

Concentration of POPs (ng/g ww) in placental tissue collected between 2009–2015. Only BDE-47 displayed a significant linear trend over the time categories (p=0.04).