Occurrence And Distribution Of Organic Micropollutants In Chinese Rural Groundwater

Groundwater serves as a main drinking water source for rural residents in China.However,little is known regarding the pollution of organic micropollutants in groundwater that may pose potential health risk.Thus,this study aims to identify the occurrence of organic micropollutants in Chinese rural groundwater as drinking water,and assess the health risk of these substances.To ensure the study on national-scale going smoothly,more than 1300 organic micropollutants were screened firstly in the groundwater samples collected from 13 drinking water wells distributed across five rural regions in the Liaodong Peninsula.Solid phase extraction and automated identification and quantification database system were applied in the process of pretreatment and analysis.A total of 80 organic micropollutants classified in 15 catagories were detected with their total concentration of 32 – 1.5×104 ng/L.Noncarcinogenic and carcinogenic risk of a part of substances was assessed.Skin absorption and oral ingestion was considered in the assessment.The noncarcinogenic risk was lower than 0.1 no matter for single compound or mixture.The carcinogenic risk for single compound was lower than 10-6,which can be neglected,as well as the joint carcinogenic risk,except the joint carcinogenic risk at two sites in Jinzhou which was higher than 10-6.The national-scale rural groundwater samples were collected in July – August,2016 and Janurary – Feburary,2017.152 samples were collected from 144 villages in 27 provinces and municipalities.106 organic micropollutants were detected with the total concentration range from not detected(n.d.)to 1.7×102 ?g/L.Most detection(86%)for single compound was at concentration less than 1 ?g/L.Phthalic acid esters(PAEs)were the typical detected contaminnats in the Chinese rural groundwater.At least one PAE was detected at 78.5% of the sampling sites,and the total concentration was n.d.– 57 ?g/L.Noncarcinogenic and carcinogenic risk was assessed for 29 compounds and 5 compounds respectively,and only oral ingestion by drinking groundwater was considered.According to the exposure factors handbook of Chinese population,the rural population exposed to the organic micropollutants in the groundwater was divided into 16 groups.For single compound,the noncarcinogenic risk and joint noncarcinogenic risk to each group of population was 10-7 – 2.In four samples,the joint noncarcinogenic risk for at least one group of the population was higher than 0.1,indicating the medium risk or unacceptable high risk.For single compound,the carcinogenic risk to each group of the population was 10-10 – 10-4.In 25% of the samples,the range of joint carcinogenic risk to at least one group of the population was 10-6 – 10-4,mainly resulted from bis(2-ethylhexyl)phthalate,which contributed more than 70% of the joint carcinogenic risk at each sampling site.The results of health risk assessment showed bis(2-ethylhexyl)phthalate was the significant element which caused the health risk to Chinese rural population.