In vitro assessment of rat lymphocyte DNA repair function following chronic drinking water exposure to chromium (VI)

Exposure to environmental contaminants may occur via the drinking water; and chronic exposure to toxicants may cause alterations in DNA repair function. Since lymphocytes are easily obtained, the capacity of these cells to repair radiation-induced strand breakage (SB) was determined and the effect of chronic, oral K2CrO4 (Cr+6) exposure on this capability was assessed. SB and repair were determined using the alkaline elution technique. Fisher 344 rats were exposed to K2CrO4 in their drinking water for 3 and 6 weeks at concentrations of 100 and 200 ppm chromium. Splenic lymphocytes were isolated and plated in RPMI 1640 with 10% FBS 18h prior to assessment of repair capacity. A dose-dependent increase in strand damage was observed following exposure of lymphocytes to 300 and 600 rads. Repair was analyzed after a dose of 400 rads. SB was repaired in a biphasic manner with >80% of repair completed within 60 min. Oral chromate exposure had no effect on either the rate or extent of repair by lymphocytes. Although chromium was detected in blood, liver and kidney, blood levels were comparatively much lower. This may indicate a lack of bioavailability of chromium to lymphocytes