BACKGROUNDPolycyclic aromatic hydrocarbons (PAHs) are classic persistent organic pollutants in the hydrosphere, lithosphere, biosphere and atmosphere, which have a harmful effect on human health by exchanging and migrating among various environmental media. Breast milk is an ideal biometric to monitor the exposure risk of mothers and infants to PAHs. Earlier research indicated that the residue levels of PAHs in breast milk from Beijing were higher in the world.

OBJECTIVESTo understand the changes in the residue levels of PAHs in breast milk in the region, the exposure of infants, and the trends and characteristics of the exposure risk of breastfeeding mothers and infants.

METHODSFor 30 first-delivery women in Beijing, a breast milk sample per month within 180 days postpartum period was collected. The PAHs and fat content of breast milk were determined by gas chromatography-mass spectrometry (GC-MS) and monitored to study the time tendency of PAHs and estimate the exposure risk of infants to PAHs.

RESULTSThe dominant pollutants were acenaphthylene, acenaphthene, fluorene, phenanthrene, anthracene, and fluoranthene. The average concentration of Σ₁₅PAHs in 180 samples was 348μg/kg lipid, which was lower than the value reported in 2005. Compared to the early reported residue level, the BaP-equivalent (BaP_eq) concentrations decreased, which were 7.89μg/kg lipid for seven carcinogenic compounds, and 8.53μg/kg lipid for 15 PAHs. For breastfeeding infants in Beijing, the mean acceptable daily intakes (EDIs) of Σ₁₅PAHs and Σ₇PAHs through breast milk were 1.51μg/day/kg b.w. and 0.19μg/day/kg b.w., respectively, which was lower than those in 2005. However, it was higher than the exposure of infants in some countries such as Czech, America, Turkey during breastfeeding, and lower than the latest research results of Lanzhou and other heavy industrial cities in China. Throughout the lactation period, the total concentration of PAHs in breast milk did not decrease significantly, but winter heating may increase the emission of PAHs in the atmosphere, making the total concentration of 15 PAHs in breast milk samples significantly higher than that in summer, autumn, and spring.

CONCLUSIONSBivariate correlations analytical results show that the concentration of Σ₁₅PAHs is not associated with age, BMI and lipid content. Limited by sample size, those results should be confirmed with perfect experiment design and sufficient samples in future studies.