Excretion kinetics and variability of urinary mercury in workers exposed to mercury vapour

SummaryDeterminations of mercury in urine were made in samples collected from workers that were: (a) exposed prior to sampling — urine has been sampled over 3 weeks' post-exposure period; (b) currently exposed — sampling on consecutive days of the working week; (c) currently exposed —urine sampled over 24 hrs, during working shift (morning or afternoon) and off work.Mercury excretion in group (a) followed a two-term exponential equation with rate constants of about 0.35 and 0.01 day−1. Regardless of exposure time pattern in all groups studied, a diurnal variation of urinary concentrations of mercury was observed with a maximum at night and morning hours, and minimal values in the afternoon. The great variability in Hg-concentrations could have been related to the time of day at which the sampling took place, and partly to variation of urine excretion rate, the 2 factors being interrelated. Only a moderate variability in urinary concentrations of mercury was found when the sampling was instituted at a constant time of day, and when the results were standardized for specific gravity of urine.