DNA-protein crosslinks as a biomarker of exposure to solar radiation: a preliminary study in brick-kiln workers

In India, fired clay bricks are produced in small-scale factories. There are 60 000 active brick kilns, providing employment to nearly 12 million people in different suboccupations. This industry is largely non-mechanized and operates from November to June. Almost all the workers are exposed to direct sunlight for 8-10 h a day. Cellular DNA-protein crosslinks (DPCs) are the biologically active nucleoprotein complexes formed between DNA and proteins. Ultraviolet light and gamma-rays, and other suspected carcinogens in humans, induce DPC formation in blood cells. DPCs have therefore been identified as a biomarker for monitoring exposure to these hazardous agents. Here we report steady-state levels of DPCs in human peripheral lymphocytes from 46 brick-kiln workers exposed occupationally for 8-10 h a day to solar radiation in brickfields and 25 unexposed controls. A significant increase (p < 0.05) in DPC content and DPC coefficients in peripheral lymphocytes was observed in the brick-kiln workers compared with the controls. The data suggest that the DPC content of lymphocytes could be a possible biomarker of exposure to solar radiation. However, further work is necessary to confirm this.