Urinary excretion of nickel after dermal application of Nigerian light crude oil.

We examined the pattern of excretion of crude oil nickel (CON) in urine and feces. Adult male guinea pigs were treated with a single dose of 5 mL/kg b.w. Nigerian Bonny light crude oil applied on the skin. Untreated guinea pigs served as controls. The CON content was measured spectrophotometrically by the dimethylglyoxime reaction following nitric acid:perchloric acid: sulfuric acid (3:1:1) digestion of blood, urine, and feces samples at 2, 4, 8, and 16 days after the crude oil application. We found a peak of CON excretion in the urine at 2 days and a return to the control level at 16 days. There was no change in the CON content in the feces during the observation time. We found a peak of CON content in the blood at 8 days and a return to control values at 16 days. The implication of these excretion and transport patterns of CON is discussed vis-á-vis the potential application of the urinary nickel content as a valid biochemical indicator of human exposure to environmentally spilled crude oil.