Delta-aminolevulinic acid dehydratase: Inhibition in ducks dosed with lead shot

Lead concentration in blood and erythrocyte delta-aminolevulinic acid dehydratase (ALAD) activity was measured in mallard ducks dosed with one all-lead shot or one lead-iron combination shot. For 2 weeks after dosage, lead in blood of ducks given an all-lead shot was fourfold higher than in those dosed with lead-iron shot. At 3 and 4 weeks, the differences in lead residues were directly proportional to lead content of the shots. ALAD activities measured at these intervals were inversely correlated (P < 0.01) with the concentration of lead in the blood, suggesting that biochemical responses to the two types of shot were dependent upon the quantity of lead present.