Preliminary Health Risk Assessment Of Heavy Metals In Baiyin District

Health risk assessment is one kind of method which is used in caculating and expressing the individual health hazard resulting from environment pollution. The author selected Baiyin district as the research area because of its serious pollution, analyzed the characteristics of heavy metals and estimated the level of health risk in order to offer powerful scientific evidence for environment management. Through retrospective analysis and field investigation of heavy mental pollution, the general orderliness and characteristics were concluded in the following manner:1. In this district, the pollution of heavy mentals Cd, Pb, Cu, Zn are evident, especially in wastewater irrigation areas. The level of heavy metals in random samples of food was below Chinese criterion except Cd in vegetable In this investigation.2. The average numerical value of lead in children's urine in this area is 0.231 ±0.15μmol/L There are 8 children with lead levels in their Urine beyond the national standard, the ratio of superscale being 11.1%.3. The health characteristics of residents in this area are as follows: (1) 63.4% of the population in this area shows the probable toxicosis symptoms due to heavy metals, especially in chronic symptoms such as neurasthenic including insomnia, headache and dizziness.The chronic symptoms are 56.6%of those affected. The acute symptom shows nephritis and gastricicism, the ratio of which is about 6.9%; (2) The female symptoms are more obvious than the male's. In the same environment, female ability of immunity is more likely to be harmed by heavy metals; (3) Different careers contact different environments. From the analysis of idiographic instances in Baiyin district, workers have more probability of contacting the thicker heavy mental. The analysis of residential health in different career populations show that people who engage in brainwork have significant symptoms in the nerve system, while the incidence of acute gastricism and ephritis of workers is higher than civil servants. It can be concluded that workers have been at serious pollution risk of heavy metals and that their health risks are bigger; (4)Children's IQ has some minus correlation with the body lead(scaled by urine lead) ,the ability of feedback has no correlation with urine lead, the capability of behavior has following correlation: the capability of behavior decreases with the increase of urine lead thickness.4. Through the investigation of heavy metals' pollution and analysis of resident's health in Baiyin district, the risk of individual health in this district was calculated by two exposure modes including intake and breath, intake can be distinguished by drinking and eating. So, the characteristic of magnitude of health risk is drinking>eating>breathing. The general risk of individual health is 2.37x10~-4/a, which is 4.5 times of the maximal acceptable risk stipulated by ICRP. While this risk may increase 2 times in the wastwater irrigative area.According to the pollution state and characteristics, the corresponding countermeasures are advanced. We must not only carry out the chemical, physical and biological restorations for the pollution soil, but also improve the eligible ratio for reducing the heavy metals' thickness in the sewage. Furthermore, the virescence measure can be used to depurate air.