Levels and profiles of PCDD/Fs, PCBs in mothers' milk in Shenzhen of China: Estimation of breast-fed infants’ intakes

Sixty breast milk samples were collected in Shenzhen, China from July to November in 2007. The samples were analyzed of the concentrations of polychlorinated dibenzo-p-dioxins (PCDDs), polychlorinated dibenzofurans (PCDFs) and polychlorinated biphenyls (PCBs). The range of upper-bound for ∑ TEQ-(PCDD/Fs + PCBs) in the samples was 4.10–35.3 pg TEQ g− 1 lipid (median: 10.6 pg TEQ g− 1 lipid; mean: 11.9 pg TEQ g− 1 lipid). The levels of the measured contaminants in the breast milk had significant correlations with the length of inhabitation period in Shenzhen (r = 0.487, p < 0.05 for PCDD/Fs, r = 0.431, p < 0.05 for PCBs and r = 0.478, p < 0.05 for ∑ TEQ-(PCDD/Fs + PCBs)), and the consumption rate of fish (r = 0.366, p < 0.05 for PCDD/Fs, r = 0.486, p < 0.05 for PCBs and r = 0.416, p < 0.05 for ∑ TEQ-(PCDD/Fs + PCBs)), respectively. Moreover, significant positive correlations were also detected between the participant's age (r = 0.305, p < 0.05 for ∑ TEQ-PCBs and r = 0.275, p < 0.05 for ∑ TEQ-(PCDD/Fs + PCBs)) and the body burdens of these contaminants respectively. It is estimated that the daily intake (EDI) of the sum of PCDD/Fs and DL-PCBs by the breast-fed infants was 5.60–161 pg TEQ kg− 1 bw per day (mean: 48.2 pg TEQ kg− 1 bw per day; median: 42.2 pg TEQ kg− 1 bw per day). The result showed that both the body burdens of PCDD/Fs and PCBs of the recruit population and the calculated EDI of the breast-fed infants were higher than those in the non-exposed areas in mainland China. This suggests that continuous surveillance on PCDD/Fs and PCBs levels in human milk is critical to more precisely evaluate the human health risk posed by the negative environmental impact in Shenzhen in the future.

Research Highlights
► This is the first study on PCDD/Fs and PCBs levels in human breast milk in the city of Shenzhen (China).
► The body burden and EDI were higher than those in non-exposed areas in mainland China.
► The body burden was higher than that in some underdeveloped countries.
► Inhabitation period and fish consumption were positively correlated with the body burden.
► Continuous surveillance on PCDD/Fs and PCBs levels in human milk is needed.