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Cancer risk assessment of soils contaminated by polycyclic aromatic hydrocarbons in Shanxi, China
Hongxue Qi, Xiuling Chen, Yi-en Du, Xianjun Niu, Fang Guo, Wanxi Li∗
College of Chemistry and Chemical Engineering, Jinzhong University, Jinzhong, 030619, Shanxi, China
To assess the human cancer risk exposed to soil contaminated by polycyclic aromatic hydrocarbons (PAHs) in Shanxi province, China, the total 33 samples in the surface soil were collected from 11 cities, and the priority 15 PAHs were analyzed using gas chromatography-mass spectrometry after the soxhlet extraction and silica-alu-mina column purification. As a result, the levels of ∑15PAH in soil varied from 66.2 to 2633 ng/g dry weight (dw) with a mean of 732 ng/g dw, and seven carcinogenic PAHs made up 42–69% of the total priority PAHs and had an average value of 367 (in the range of 33.2 to 1181) ng/g dw. Accordingly, the total concentrations of benzo [a]pyrene equivalents (BaPeq) for 15 PAHs ranged from 10.3 to 358 (average 98.3) ng/g dw, and the seven carcinogenic BaPeq accounted for above 90%. Subsequently, the possible sources of PAHs in soil were identified by isomer ratios, demonstrating that the combustion contributed to the main source. Finally, the incremental lifetime cancer risks (ILCR) of soil contaminated by 15 priority PAHs were estimated using the targeted che-mical-specific approach. ILCR values were considered to be greater than 1 × 10−6 in 16 of 33 sites and followed a decreasing trend of adulthood > childhood > adolescence. Subsequently, the analysis of variance was per-formed by average ILCR value among the 11 cities (n = 3, p < 0.01), which indicated that the potential low cancer risk significantly increased for nearby residents in two areas, including Datong and Xinzhou, with the ILCR values of 4.61 ± 1.93 and 3.92 ± 2.54 per million, respectively. Therefore, the consumption of tradi-tional coal should be controlled and partially replaced with the alternative 14042-01-4 sources. And the rigorous monitoring should be termly warranted to avoid the cancer risk for human being in agricultural area of Shanxi, China.
Polycyclic aromatic hydrocarbons (PAHs) are ubiquitous con-taminants deposited on terrestrial and aquatic surfaces and accumu-lated in water bodies, soil, plants, and even organisms through food chains (Wilcke, 2007). They originated mainly from anthropogenic sources and natural combustion processes.
Soil is the most important sink for PAHs, their accumulation through food chains will ultimately result in the toxic, mutagenic, and even the potential carcinogenic eﬀects on human being (Lemieux et al., 2015). Thus, 16 PAHs were identified as the priority pollutants by United States Environmental Protection Agency (USEPA) (Keith, 1979). The incremental lifetime cancer risk (ILCR) model is currently ad-vocated (USEPA, 1991) and adopted (Man et al., 2013; Peng et al., 2011) to characterize the cancer risks of these compounds from the ingestion, dermal contact, and inhalation exposure scenarios. Typically, estimates of ILCR are based on the benzo[a]pyrene (BaP) equivalent
concentrations (BaPeq). Assuming concentration addition, BaPeq was calculated as the sum of the individual PAH in the same class according to the toxic equivalence factor (TEF), ranging from 0.001 to 1 (Nisbet and Lagoy, 1992; USEPA, 1993). Under most regulatory programs, an ILCR values between 10−6 and10−4 indicate the potential low risk, whereas ILCR values above 10−4 indicate the potential high risk.
2.3. Cancer risk assessment
2.2. Chemical analysis
where Csoil is the concentration of BaPeq in soil (mg/kg), IngR is in-gestion rate of soil, EF is exposure frequency, ED is exposure duration, CF is conversion factor, SFO is oral slope factor for Bap, BW is average body weight, AT is averaging time, SA is skin area, AFsoil is skin ad-herence factor, ABS is dermal absorption factor, GIABS is the gastro-intestinal absorption factor, IUR is inhalation unit risk, PEF is the particle emission factor, AT∗ is averaging time. All the parameters are presented in Table S2.
2.4. Statistical analysis
Significant diﬀerences of the total cancer risk were determined by the analysis of variance. The multiple comparison tests were performed by Tukey Test using SPSS 16.0 software, and significant diﬀerences
Fig. 1. Locations of the sampling sites in Shanxi province, China (DT: Datong, 3. Results and discussion
SZ: Shuozhou, XZ: Xinzhou, TY: Taiyuan, YQ: Yangquan, LL: Lvliang, JZ: 3.1. Contamination levels
Jinzhong, LF: Linfen, CZ: Changzhi, YC: Yuncheng, JC: Jincheng).
agricultural soil in Shanxi has not been fully investigated, and the