Polycyclic aromatic hydrocarbons in breast milk of obese vs normal women: Infant exposure and risk assessment

Abstract

Biomonitoring of human breast milk is one of the best ways to identify body burdens of contaminants and associated risk estimation. The objectives of the current study were to evaluate milk concentrations of persistent organic pollutants (POPs), mainly polycyclic aromatic hydrocarbons (PAHs), associated exposure estimation, and the role of body mass index (BMI) in their bioaccumulation. A total of 45 breast milk samples were collected from 24 women with BMI > 30 (obese) and 21 women with BMI < 25 (18.5–24.9, normal) from 14 different counties surrounding Lubbock in west Texas/New Mexico (age range: 18–34 years). Samples were analyzed using high resolution gas chromatography coupled with mass spectrometry. A total of 31/45 (69%) of samples tested positive for PAHs. Phenanthrene was the most frequently detected PAH followed by pyrene and fluoranthene. The mean of individual PAH concentration for all samples ranged from 0 to 25.1 ng/g milk fat; the sum of all means of individual PAHs was 146.9 ng/g milk fat. The mean concentration of total PAHs in the BMI > 30 group was 224.8 ng/g milk fat, which was approximately 4 times the mean concentration of total PAHs in the BMI 18.5–24.9 group (57.9 ng/g milk fat). None of the samples from the BMI 18.5–24.9 group contained higher molecular weight (5–6 rings) PAHs, while in the BMI >30 group, a total of 11 PAHs including listed EPA priority pollutants were observed. In this study, benzo(b)fluoranthene was found to contribute the highest percentage of carcinogenic PAHs (32.08%), yet it was not detected in any samples from the BMI 18.5–24.9 group. The estimated total PAHs intakes by infants via obese and normal mothers' milk were 1.26 and 0.32 (μg/kg/day), which are 0.049 and 0.003 (μg/kg/day) B[a]P equivalent, respectively. These findings suggest that breastfed babies from obese mothers are potentially at higher risk of exposure to carcinogenic PAHs.