Monitoring blood lead levels in workers overexposed to occupational lead: an analysis of Israeli data

In a retrospective cohort study, we followed the blood lead [Pb(B)] and zinc protoporphyrin (ZPP) determinations of 292 workers found to have Pb(B) levels above the biological exposure index (BEI) during 1987-1993. The results indicated that (a) 22.6% of these workers were never retested for Pb(B) during the follow-up period; (b) 38.5% of the workers tested in the first year of the follow-up continued to exhibit Pb(B) levels above the BEI (84.7% of them also had ZPP > or = 100 micrograms/dl); (c) about 25% of the remaining cohort had at least one more result above the BEI during the fourth, fifth, and sixth years of follow-up; and (d) the incidence density rate of recurrence of Pb(B) concentrations above the BEI was 0.236. We recommend the establishment of a target value lower than the BEI that should be reached before the reinstatement of the overexposed worker. In our view this target value, combined with an efficient control of industrial hygiene conditions, will decrease the rate of recurrence of overexposure.