Risk assessment of BTEX in the groundwater of Songyuan region of Songhua River in China

BTEX compounds (benzene, toluene, ethylbenzene and xylenes (m-, p-xylene and o-xylene)) in shallow groundwater were investigated in 16 monitoring wells of the Songyuan region (Songhua River basin). Mean concentrations of benzene, toluene, ethylbenzene, and xylenes were found to be 1.53 μg/L, 1.76 μg/L, 2.11 μg/L and 0.30 μg/L, respectively. Ecological and human health risk assessments were conducted to evaluate potential adverse effects of the BTEX compounds in terms of toxicity. Toluene posed a severe ecological risk, xylenes a moderate risk, while benzene and ethylbenzene were both considered to be a low risk. The mean cancer risk for benzene was estimated to be 1.14 × 10⁻⁶, which is higher than the acceptable risk level of 1.0 × 10⁻⁶. The mean non-carcinogenic risks for benzene, toluene, ethylbenzene, and xylenes were lower than the standard threshold level of 1.0, both individually and cumulatively. In terms of a screening assessment, these results indicate that BTEX in groundwater may pose a threat to the ecosystem and residents in the Songyuan region of the Songhua River basin. This information will be useful for the further evaluation and risk management of groundwater in this area.