[Distribution and health risk of HCHs and DDTs in a contaminated site with excavation]

Air samples were collected to analyze the distribution of HCHs and DDTs around a contaminated site during its excavation. The carcinogenic risks and non-carcinogenic risks through breath exposure were studied by health risk assessment modes. The results showed that, there was an obvious seasonal variation of HCHs and DDTs in air around the excavating area. The concentrations of HCHs and DDTs were higher in winter and autumn, lower in spring and summer. The Σ HCHs concentration ranged from 5.65 ng x m(-3) to 133 ng x m(-3), and the average value was 28.6 ng x m(-3); Σ DDTs concentration ranged from 4.48 ng x m(-3) to 2 800 ng x m(-3), and the average value was 457.3 ng x m(-3) in winter. However, the Σ HCHs concentration was between 6.23 ng x m(-3) and 26.4 ng x m(-3), and the average value was 15.1 ng x m(-3) in spring; the Σ DDTs concentration was between 3.17 ng x m(-3) and 8.1 ng x m(-3), and the average value was 6.1 ng x m(-3) in summer. So the pollution could be reduced by excavating in spring and summer. The concentrations of HCHs and DDTs in the residents area were negatively correlated to the height (P < 0.05, n = 33 ). The carcinogenic and non-carcinogenic risks of adult residents through respiration to residents near the excavating area were lower than the acceptable level, while the excavating process caused carcinogenic and non-carcinogenic risks to young residents to some extent. In order to decrease the risks, measures should be taken to restrain the pollutants in the excavation area diffusing into the air.