| Health risk assessment is one kind of method which is based on risk degree and expressing the individual health hazard resulting from environmental pollution quantitatively.The author selected Shen-fu irrigation area as the research area,which is a typical petroleum hydrocarbon irrigation area in China,analyzed the characteristics of heavy metals and estimated the level of health risk in order to offer powerful scientific evidence for environmental management,and also for making the laws and regulations of the irrigation area.Through field investigation of heavymetal pollution,the general orderliness and characteristics were concluded as follows:(1) In the research area,farmland soil and grain were evidently polluted by heavy metals.The results showed that soils of Shen-fu irrigation area were contaminated by Cd,Hg and Ni to a different extent,and the content of Cd,Hg and Ni are 7.4,4.8,1.6 times of their corresponding criterions respectively.The grain(rice and maize) were contaminated most seriously by heavy metal Hg,and the content of Hg in rice and maize were maximumlly 101.5 and 95 times of Chinese criterion.Then the content of Cr in rice and maize were maximumlly 5.7 and 8.4 times of Chiese criterion.The level of heavy metals in groundwater was below Chinese criterion in this investigation.(2) The results of exposure assessment on heavy metals pollution showed that average daily dose(ADD) of Cu is maximum among seven heavy metals for whether adult or children,while Cr took the second place,and Cd was the lowest level.The minimum ADD is 2 order of magnitude lower than the maximum ADD;The ADD of Cd and As of adult is larger than that of children,but for other heavy metals,it was just the opposite.The contribution rates of heavy metals exposure dose were all above 80%in the pathway of grain feeding,which is far higher than that in other pathways.(3) Studies on health risk of heavy metals in the reaesrch area showed that carcinogenic risk is higher than non-carcinogenic risk for whether adult or children.For adult,the carcinogenic risk and non-carcinogenic risk are 4.35×10-5 and 5.15×10-3 respectively,and the carcinogenic risk was above the acceptable risk level 3.5×10-3, while for children,the carcinogenic risk and non-carcinogenic risk were 1.16×10-4 and 4.16×10-3 respectively,two values both were above the acceptable risk level, indicating that carcinogenic risk was evident for adults and two types of health risk both were evident for children.Also,it could be concluded that the pathway of grain feeding is the most primary exposure pathway.Compared with adults,children are more easily affected by heavy metal pollution in soil ingesting pathway.
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