Concentrations, sources, and risk assessment of polychlorinated biphenyls in vegetables near a waste-incinerator site, South China.

Numerous studies have reported polychlorinated biphenyl (PCB) concentrations in soil, root, and aerial parts of vegetables. However, few studies have measured the contribution of PCBs bound to particles in air in relation to uptake by vegetables. In the present study, PCB concentrations were measured in five types of vegetables, soil, and settled air particle samples from two sites (at a domestic waste incinerator and at 20 km away from the incinerator) in Guangzhou, South China. ∑PCB concentrations in rhizosphere soil samples from the two sites ranged from 17.2-77.7 to 5.48-25.57 ng/g, respectively. ∑PCB concentrations in aerial parts of vegetables were greater than those in rhizosphere soils and roots with median values of 108 and 47.08 ng/g, respectively. Among the five types of vegetables studied, the highest concentration of PCBs was found in bitter lettuce. No significant correlation between PCBs in soil and roots or aerial parts of vegetables was observed. However, principal component analysis indicated that settled air particles were the dominant source of PCBs in the aerial parts of vegetables. In addition, similar PCB congener profiles were found in the aerial parts of vegetables and settled air particles. This suggests that foliar uptake of PCBs is an important pathway. Risk assessment indicated that human exposure to PCBs by way of dietary intake of vegetables from incinerator sites would result in high risk.