Protective effects of selenium against DNA adducts formation in Inuit environmentally exposed to PCBs

摘要

Dietary habits that expose populations to potential toxicants as well as protective agents simultaneously is a realistic scenario where a meaningful assessment of the interactions and net benefit or damage can be made. A group of Inuit from Salluit, Northern Canada are exposed to high levels of PCBs and selenium, both present in the Inuit traditional foods such as blubber from sea mammals and fatty fish. Blood samples were collected from 83 Inuit, 22–70 years old. Blood selenium and PCB levels were determined previously and ranged from 227 to 2,069 µg/L and 1.7 to 143 µg/L, respectively. DNA isolated from white blood cells were analyzed by modified ³²P-postlabeling adductomics technology that detects a multitude of highly polar to lipophilic adducts. The levels of 8-oxodG adducts ranged from 470 to 7,400 adducts/10⁹ nucleotides. Other as yet unidentified polar adducts showed a 30 to 800–fold inter-individual variability. Adduct levels were negatively associated with PCB and selenium levels. The subjects were classified into high and low ratio groups, with respect to selenium/PCB. In the high ratio group, the coefficient of selenium is significantly negatively correlated with 8-oxodG (r = −0.38, p = 0.014) and total adducts (r = −0.41, p = 0.009) while there was no correlation within the low selenium/PCB group. This study suggests increasing selenium has mitigating effect in reducing DNA adducts and therefore, possible negative effects of PCB were not rendered. A protective effect of selenium is highlighted.