Arsenic Contamination in Drinking Water: Exposure and Health Effects in an Inner Mongolian Population
Creators: name: Schmitt, Michael T.
Publisher: name: The University of North Carolina at Chapel Hill University Libraries
Year: 2002

description: Arsenic is a naturally occurring metal to which humans are exposed through air, food, soil, and water. Chronic exposures to arsenic have been reported to be associated with a variety of adverse health effects including cardiovascular and pulmonary disease, neurological and developmental effects, and cancers of the skin, bladder, kidney, lung, and liver. The ground water in Ba Men, located in Central West Inner Mongolia, China is naturally contaminated with arsenic at concentrations ranging from 0.3 μg/l to 1446 μg/l. Various adverse health effects in this region, including skin hyperkeratosis and other chronic diseases, have been linked to high-arsenic exposure from the drinking water. A pilot study was designed to detect internal arsenic levels using biomarkers of exposure, urine, nails, and hair samples, and to evaluate DNA and chromosomal damage in buccal cells. Arsenic was detected in the drinking water samples of the 19 exposed study subjects with a mean level of 527.5±23.6 μg/l, while the 13 control subjects had a mean level of 4.4 μg/l±1.0. Arsenic detected in the internal exposure biomarkers for the exposed group compared to the control group was statistically significant for urine samples (632.7 μg/l and 28.5 μg/l, respectively, p<0.0001), nail samples (32.02 μg/g and 3.36 μg/g, respectively, p<0.0001), and hair samples (12.42 μg/g and 0.798 μg/g, respectively, p<0.0001). Biomarkers of effects were examined using the micronucleus assay to detect chromosomal abnormalities and the DNA laddering assay to detect DNA fragments. MN induction in the high-arsenic exposed group was 3.4 fold higher (2.21MN/1000 buccal cells) compared with the control group (0.65MN/1000 buccal cells)(statistically significance at p<0.01). DNA fragments containing <100bp in length were seen in 89% of the individuals in the exposed group compared to 15% in the control group (p<0.0001). Correlations were determined to establish relationships between the arsenic in the drinking water, internal exposure markers, and biomarkers of effects.The biological exposure markers (urine, nail, and hair samples) all statistically correlated with the water arsenic levels. The strongest correlation was between the urine samples and water arsenic levels (Spearman r=0.8397, p<0.0001). The strongest correlation among the internal exposure markers was between urine and nail samples (Spearman r=0.7776, p<0.0001). The biomarkers of effects were statistically correlated with the arsenic water levels and all three internal exposure markers. The strongest correlation among the internal exposure makers and the biomarkers of effects was between the hair samples and DNA fragments (Spearman r=0.7318, p<0.0001). The two biomarkers of effects were statistically correlated with one another (Spearman r=0.5238, p<0.01). These results indicate that the individuals living in Ba Men are chronically exposed to arsenic via drinking water and reveal evidence of the genotoxic effects of arsenic in human cells. Arsenic levels measured in urine, nail, and hair samples can be useful as biomarkers of exposure. Micronuclei and DNA fragmentation patterns can be potentially useful as biomarkers of effects for assessing chromosome damage and DNA damage in human populations chronically exposed to arsenic via drinking water sources.