Behaviour of urinary nickel in low-level occupational exposure

The study tested the feasibility of using urinary nickel (Ni-U) as a biological indicator to assess exposure to soluble nickel compounds in electroplating departments at concentrations well below the current TLV-TWA. Two groups of workers were studied: Group A, consisting of 13 subjects and Group B consisting of 10 subjects, with an average weekly nickel exposure of nickel in air (Ni-A) greater than or equal to 10 micrograms/m3 (Group A) and less than 10 micrograms/m3 (Group B). Air samples and urine specimens were taken on 4 consecutive days from Monday to Thursday. The mean Ni-U levels in both groups were significantly higher than in the reference group. The Ni-U levels in end-of-shift spot samples showed a tendency to increase over the week; this trend was more marked in Group A. Closer correlations between Ni-A and Ni-U were found using the postshift Ni-U values of Thursday: the test was well correlated both with the Ni-A levels of the same day and with the mean levels of the previous days. The results suggest that Ni-U is a sufficiently sensitive indicator for use in monitoring low-level occupational exposure, especially if Ni-A concentrations are above 10 micrograms/m3.