Assessment of DNA damage in peripheral blood lymphocytes of individuals susceptible to arsenic induced toxicity in West Bengal, India.

Assessment of DNA damage was carried out using alkaline comet assay in lymphocytes of 30 individuals exposed to high levels of arsenic (247.12+/-18.93 microg/l) through contaminated groundwater in North 24 Parganas district, West Bengal, India. All of them exhibited high arsenic contents in nail (4.20+/-0.67 microg/g), hair (2.06+/-0.20 microg/g) and urine (259.75+/-33.89 microg/l) samples and manifested various arsenical skin lesions. Unexposed samples were collected from 30 residents of the unaffected East Midnapur district with very little or no exposure to arsenic (7.69+/-0.49 microg/l) in drinking water. The results were evaluated principally by manual analysis of comets and partly by computerized image analysis. Both the analytical methods exhibited a high degree of agreement in results. The exposed participants expressed significantly higher DNA damage (p < 0.01) in their lymphocytes than the unexposed participants. Alkaline comet assay was also combined with formamidopyrimidine-DNA glycosylase enzyme digestion to confirm that arsenic induced oxidative base damage in the lymphocytes. Significant positive trend effects of comet lengths in relation to arsenic levels in water prove that DNA damage can be used as a sensitive biomarker of arsenic exposure. This study demonstrates that arsenic induced significant DNA damage in the exposed participants, which could correspond to a higher susceptibility to arsenic induced toxicity and carcinogenicity.