Research On The Volatile Carcinogen Contaminated Site Surrounding Crowd Health Risk

It is closely related to the petrochemical contaminated site with the happen to the sensational of Lanzhou City Water benzene exceeded incident On April 11,2014.To protect the safety of drinking water in Lanzhou City and avoid the recurrence of local leakage of pollutants into the artesian ditch, Gansu provincial government launched the water pipeline surrounding contaminated site remediation projects. The project carried out the remediation of contaminated soil and groundwater. The focus of the work concentrates on reducing the pollutant concentration, in order to let it meet the national standards after the remediation. This is based on environmental security considerations and it can greatly reduce environmental risks. However, there ignores an important issue, that’s during the construction, when the contaminated soil was excavated, the volatile organic compounds of benzene were released. The volatile organic compounds will have a great impact on the air environment and the health of construction person and residents around the site. In order to quantitatively evaluate the risk level of volatile organic compounds on human health and the ambient air quality, the paper takes benzene as an example from the perspective of human health and air pollution. This paper mainly carried out the following aspects of the research:(1)Through literature review and other methods, the paper estimates fugitive emission source strength.And it predicts the maximum ground concentration of benzene in contaminated soil and the percentage of the maximum ground concentration by using atmospheric estimation model, to quantitative analyze the effect on the air environment.(2)The paper collects the information on the management of site remediation projects, analyses the toxic effect of benzene and the exposure pathway to human body by means of hazard identification. It takes the perfect and mature health risk assessment system of contaminated site to analyze benzene’s cancer risk and hazard quotient of the residents’ health around the site, and analyze the risk contribution rate of exposure. And then determine what the greatest risk of exposure pathways impact on human health arising.The main results are as follows:(1)When excavating the heavy pollution area, the volatile amount of benzene is large. The heavy pollution area’s emission source strength of benzene is 121.00g/h, other regional source of emission is 3.86g/h in the first layer of soil. Similarly, the emission source strength of benzene is respectively 6063.00g/h and 3.92g/h in the second layer of soil. The emission source strength of benzene is respectively 222.90g/h,208.80g/h and 32.07g/h in the second layer of soil.(2)The maximum ground concentration of benzene was 4.86mg/m3 during soil excavation. The maximum concentration of the target rate was 202.5%. The concentration range of benzene to the village of Taoyuan and Jiajiabao is 0.03-2.85mg/m3 and 0.04-2.85mg/m3.(3)The total cancer risk level of benzene to the residents around the site is 2.20×10-4.And it is far greater than the acceptable cancer risk level (10-6). The hazard index of benzene is 26.1, and it is far greater than the acceptable non-cancer risk level (1.0).(4)The total cancer risk of the inhalation of soil particle and the inhalation of gaseous pollutants from topsoil in the outdoor air exposure pathways are exceeded. The cancer risk of the inhalation of soil particle exposure pathway is the biggest (1.97×10-4). The hazard index of the oral ingestion of soil, the inhalation of soil particle and the inhalation of gaseous pollutants from topsoil in the outdoor air exposure pathways are exceeded, the hazard quotient of the inhalation of soil particle exposure pathway is the biggest (13.7).(5)The cancer risk and hazard quotient contribution rate of benzene caused by the soil surface, middle and lower levels are 27.91%,48.64%,23.45% and 54.19%,8.07%,37.74% respectively.(6)From the perspective of carcinogenic effect, the biggest contribution rate of exposure pathway is the inhalation of soil particle, and it is over 89.55%. The exposure pathway of second biggest contribution rate is the inhalation of gaseous pollutants from topsoil in the outdoor air, over 9.86%. The remaining exposure pathways’ cancer risk is less than 0.59%. Similarly, from the perspective of non-carcinogenic effect, the biggest contribution rate of exposure pathway is the inhalation of soil particle, and it is over 52.49%. The exposure pathway of second biggest contribution rate is the inhalation of gaseous pollutants from topsoil in the outdoor air, over 21.03%. The remaining exposure pathways’ hazard quotient is 26.48%.