Urinary mercury clearance of dental personnel after a longterm intermission in occupational exposure

The objective of this study was to get an estimate of the overall halftime for clearance of urinary mercury after cessation of a mercury vapor exposure. Ten dentists and dental nurses were selected and their urinary mercury excretion rates prior and after a summer vacation were measured. Estimates of their basic mercury excretions, originating from the environmental background and their own amalgam restorations, were individually subtracted to get the contributions deriving from occupational work. If assuming a first order of kinetics for the clearance of urinary mercury a median value of 41 days was achieved for the halftime searched, a value somewhat lower than those previously published. An explanation might be that the tailing effect of the decay curve here was eliminated by the taking of the background excretions into account.