During 1 h two healthy volunteers, not earlier exposed occupationally to lead, inhaled about 100 mg of lead as a mixture of lead oxides and lead sulfate. Maximum blood lead (PbB) concentrations of about 0.5 mg/1 and minimum blood cell delta-aminolevulinic acid dehydratase activities (ALAD) (6% of the preexposure values) were observed within 38 h after exposure. PbB and ALAD returned to preexposure levels after about 300 and 150 days. A highly significant correlation between ALAD and PbB was seen even at lead levels in the range 0.1-0.2 mg/1. Delta-aminolevulinic acid, coproporphyrin and lead in the urine (ALAU, CPU, and PbU, respectively) increased. The peak levels occurred after about 15 h for ALAU and CPU and after about 24 h for PbU. There was a very good correlation between log PbU and lin PbB. ALAU increased already at PbB levels of about 0.3 mg/1.

Key terms blood; blood lead; blood lead level; coproporphyrin; dehydratase activity; delta-aminolevulinic acid; delta-aminolevulinic acid coproporphyrin; delta-aminolevulinic acid dehydratase activity; erythrocyte; excretion; experimental exposure; exposure; follow up; half-time; heavy exposure; lead; lead dust; male subject; man; short exposure; urinary excretion; urine