Health Risk Assessment Of The Typical Organic Pollutants In The Groundwater Of Xihe River Area

Health risk assessment using Hazard Degree as the evaluation index is an effective quantitative method to describe the relationship between human health and environment pollution. Based on the investigation of the groundwater in Xihe River Area, the status and characteristics of POPs (Persistent Organic Pollutants), such as PAHs (Polycyclic Aromatic Hydrocarbons), PCBs (Polychlorinated Biphenyls), OCPs (Organochlorine Pesticides) were analized systematically in this paper. The CSOIL exposure model and health risk assessment model used were proposed by Holland RIVM (Rijksinstituut voor Volksgezondheid en Milieu) and US EPA which were applied to quantify the exposure dose and health risk from the different exposure pathways, such as crop ingestion, drinking water, inhalation and demal ingestion in the bathing. Results were showed as follows:1,PAHs pollution in the groundwater of Xihe River area was mainly caused by all low and some high ring aromatic hydrocarbons. In addition, there had a degressive tendency from upstream to downstream of Xihe River, but not with the distance from Xihe River. The content of the low replace biphenyl in PCBs was higher. The concentration had no regularity with the direction flow of Xihe River and the distance from Xihe River. The detected rate of OCPs was high, but the concentration was low. And there had a degressive trend from upstream to downstream of Xihe River, but not with the distance from Xihe River. The detected rate of oil pollution was 100%, and the concentrations were higher than the drinking water hygiene standards. And the gradient of the concentration was small in the sampling points, which had not obvious change with the direction flow of Xihe River and the distance from Xihe River.2,In the detection of 12 PAHs, only the quantities of high ring PAHs, Baa, Chr and Bbf, exceed the National Recommended Water Quality Criteria of US EPA. The over-limit ratios were 53.3%,0.03% and 30%, respectively. The largest over-limit multiples were 29.5,3.3 and 4.6 times, respectively. The over-limit ratio of PCBs was 37.9%, the over-limit multiple was 9.2 times. When 9 kinds of OCPs were monitored, there were 7 species were exceed. The over-limit ratios of alpha-BHC, heptachlor, aldrin, dieldrin, p,p'-DDE, p,p'-DDD and p,p'-DDT were 10.3%,65.5%,0.03%,69.0%,41.4%,0.07% and 17.2%, respectively. The largest over-limit multiples were 8.4,86.9,15.3,37.7,7.3,3.9 and 6.5 times, respectively.3,PAHs in the groundwater mainly originated from oil pollution. The main source of PCBs was domestic production of Aroclor1221. OCPs were from local pollution, including the pesticides application, long-distance transmission or degradation of pesticide.4,Crop ingestion and drinking water are the most important exposure pathways in the human health risk assessment of groundwater, when non-carcinogenicity organic pollutants or carcinogenicity organic pollutants were concerned. The maximum of total health risk index which cuased by non-carcinogenicity organic pollutants from crop ingestion, drinking water, inhalation and demal ingestion in the bathing was 1.65×10-3, and the average is 5.72×10-4 (far below 1). The maximum of total annual health risk which caused by carcinogenicity organic pollutants from crop ingestion, drinking water, inhalation and demal ingestion in the bathing was 1.87×10-5 a-1, the average was 3.13×10-6 a-1 (below 5.0×10-5 a-1). The results calculated were acceptable.