Rats retain chromium in tissues following chronic ingestion of drinking water containing hexavalent chromium

Humans have sometimes been exposed to as much as 10 ppm Cr(VI) in drinking water from contaminated wells. The risks to these individuals are not well understood because the digestive tract reduces some of the Cr(VI) to the le ss bioavailable Cr(III) prior to absorption, and the disposition of the rem aining Cr(VI) has not been well studied. We determined tissue Cr concentrat ions in rats after chronic ingestion of Cr(VI) in drinking water at concent rations relevant to human exposure levels. Adult male and female Fischer 34 4 rats consumed ad libitum 0, 0.5, 3, or 10 ppm Cr(VI) as K2CrO4 in drinkin g water for 44 wk. Rats then were given deionized water 4-6 d prior to samp le collection. Females given 3 or 10 ppm Cr(VI) consumed more Cr(VI) per un it of body weight than did males. Bone Cr concentrations were significantly elevated in rats that drank 10 ppm Cr(VI). Renal Cr concentrations were si gnificantly elevated in male rats that drank 3 or 10 ppm Cr(VI) and in fema le rats dosed with 10 ppm Cr(VI). Female rats had elevated liver Cr concent rations after drinking 3 or 10 ppm Cr(VI). Testicular Cr concentrations wer e slightly elevated in rats that drank 10 ppm Cr(VT). Brain, ovarian, and w hole-blood Cr concentrations were below detection limits in all exposure gr oups. Although tissue Cr accumulation may have resulted from absorption of Cr(III), it is poorly absorbed. Therefore, the increased tissue retention m ay also have resulted, in part, from increased absorption of Cr(VI) and its subsequent uptake from the systemic circulation.