Association of arsenic levels in soil and water with urinary arsenic concentration of residents in the vicinity of closed metal mines

Abstract

Arsenic (As) pollution in the surroundings of metal mines has been observed, and may induce serious health problems, in particular cancer. Health hazard attributed to As in contaminated soil and water in the vicinity of closed or abandoned metal mines may be high. Little is known about how environmental exposure to As has affected the health of resident near closed metal mines. The objectives of this study were to compare the urinary level of As for those living near closed metal mines (the exposed group) with that of non-exposed group; and to investigate the correlation between As levels in soil (SoilAs) and water (WaterAs) and the urinary levels (UrineAs) of residents in the exposed group. Data for SoilAs and WaterAs were obtained from the national environmental survey performed between 2003 and 2005 by the Ministry of Environment in Korea. To measure UrineAs, 2674 and 237 subjects were selected from 67 closed metal mines (exposed areas) and two rural areas (non-exposed areas), respectively. Five milliliters of urine samples were taken, and graphite furnace atomic absorption spectrometry was used to analyze UrineAs. Of all the exposed areas, high SoilAs and WaterAs areas that exceed the Korean standards of As in soil (6 mg/kg-soil) and stream or groundwater (0.05 mg/l-water) were classified to evaluate the health risks in high polluted areas. Also, high UrineAs group was defined as 20 μg/g creatinine or more. Student's t-test was performed to compare the UrineAs level between the exposed and non-exposed groups. The odds ratio (OR) was calculated by a logistic analysis to evaluate the risk for high UrineAs level from high SoilAs and WaterAs areas. The mean of urinary As were 8.90 ± 8.34 μg/g-creatinine for the exposed group and 7.68 ± 4.98 μg/g creatinine for the non-exposed group, respectively; and the significant difference of urinary As level was observed between both groups (p<0.05). Moreover, the means for urinary As of people in areas with high As level in soil and water were significantly higher than that for the control areas (p<0.001), and these differences were more pronounced for the As level in water. The odds of subjects with high UrineAs were positively and significantly associated with living in the areas with high As level in soil (OR=1.62; 95% C.I.=1.13-2.31). These associations were much stronger for the areas with high WaterAs (OR=3.79; 95% C.I.=2.32-6.19). These results indicate that the high level of As in environment may increase the risk of having high urinary As level of people in the exposed areas.