Polycyclic aromatic hydrocarbons in human milk of nonsmoking U.S. women

The determination of polycyclic aromatic hydrocarbons (PAHs) in human milk is relevant in assessing the dose to mothers and infants. Since measurements for the United States are lacking, we analyzed 13 PAHs in human milk from 12 nonsmoking American mothers. Analytes were extracted from milk by using a combination of centrifugation, liquid-liquid, and solid-phase extraction techniques. Following method validation with spiked bovine milk, PAH concentrations in human milk were determined by isotope dilution gas chromatography/mass spectrometry. Phenanthrene, fluorene, fluoranthene, and pyrene were found at median concentrations of 11.8, 3.0, 1.6, and 1.1 ng/g milk fat, respectively, whereas 9 additional analytes including benzo[a]pyrene were not detected (<0.04 ng/g). Calculated average daily doses from ingestion (high: 75.8, phenanthrene; low: 6.1 ng/kg/day pyrene) were compared to doses from air pollution inhalation. Milk ingestion accounted for 47.9-81.4% of the total dose of individual PAHs to the infant. However, calculated total average daily doses of phenanthrene and pyrene from ingestion and inhalation combined (12.2 to 110.3 ng/kg-day, respectively) were 3 orders of magnitude lower than documented doses known to cause health effects. These first measurements of PAH levels in U.S. human milk are comparable to concentrations reported previously for European and Asian women.