Sources and health risks of PM2.5-bound polychlorinated biphenyls(PCBs) and organochlorine pesticides(OCPs) in a North China rural area

Polychlorinated biphenyls(PCBs) and organochlorine pesticides(OCPs) are typical persistent organic pollutants(POPs),which have high toxicity,bioaccumulation and long-distance transfer capability.Daily variation,sources of PcBs and OcPs in PM2.5 are rarely explored in polluted rural area.Here,the sources and health risks of the PcBs and OcPs were evaluated for 48 PM2.5 samples collected in winter 2017 in Wangdu,a heavy polluted rural area in the North China Plain.The average diurnal and nocturnal concentrations of E18 PCBs and∑15OCPs were 1.74-24.37 and 1.77-100.49,11.67-408.81 and 16.89-865.60 pg/m3,respectively.Hexa-CBs and penta-CBs accounted for higher proportions(29.0% and 33.6%) of clean and polluted samples,respectively.Hexachlorobenzene(HCB) was the dominant contributor to OCPs with an average concentration of 116.17 pg/m3.Hexachlorocyclohexane(EHCHs) and dichlorodiphenyltrichloroethane(EDDTs) were the other two main classes in OCPs with the average concentrations of 4.33 and 15.89 pg/m3,respectively.β-HCH and p,p’-DDE were the main degradation products of HCHs and DDTs,respectively.The principal component analysis and characteristic ratio method indicated both waste incineration and industrial activities were the main sources of PCBs,contributing 76.8% and 12.7%,respectively.The loadings of OCPs were attributed to their application characteristics and the characteristic ratio method reflected a current or past use of OCPs.Health risk assessment showed that the respiratory exposure quantity of doxin-like PCBs(DL-PCBs) and the lifetime cancer risk from airborne OCPs exposure was negligible,while the other exposure modes may pose a risk to human bodies.