The pollution and health risk of polychlorinated biphenyls in vegetables in e-waste recycling pollution area

Polychlorinated biphenyls (PCBs) are one of the typical persistent organic pollutants, which have carcinogenicity, neurotoxicity and endocrine disrupting effects. Due to the crudely electronic waste (e-waste) recycling, the environment in study area was seriously polluted by PCBs. It posed a threat to human health by environmental and dietary exposure. According to our previous survey, the proportion of vegetables in the dietary structure of local residents was very large, and the vegetables were contaminated by PCBs. Samples of farmland vegetables, soil, air, and water were collected from e-waste recycling pollution area, remediated area and non-dismantling control area. By determining and comparing the pollution levels and characteristics of PCBs in these samples, the source of PCBs in vegetables was analyzed. With the help of US EPA risk assessment model, the health risks of residents exposed to local vegetables with PCBs contaminated were assessed. The results showed that the average concentrations in three researching areas were 226.68, 58.31 and 35.65 ng/g. Among them, the PCBs pollution in leafy vegetables was significantly higher than that in underground rhizomes and legumes. The di-chlorinated to tetra-chlorinated congeners occupied largest proportion in the vegetables. The average PCBs concentration of farmland soil samples in e-waste recycling pollution area was 315.90 ng/g, and the main PCB homologs were lower chlorinated. The average PCB concentrations of air in three area were 103.59, 35.40 and 13.69 ng/m 3 , and the lower chlorinated congeners occupied largest proportion. There was no significant difference of the PCB levels between different irrigation water samples from e-waste recycling pollution/remediated area and non- dismantling control area. Atmospheric deposition and soil absorption were the potential sources of PCBs in vegetables. Risk assessment indicated that the lifetime excess carcinogenic risk and non-carcinogenic risk for residents in recycling pollution area were 1.01×10 - 4 and 2.54, both of them were higher than the acceptable risk level. The local restrictions on vegetable cultivation and the planting structure adjustment were suggested.