The effects of environmental lead exposure and in vitro zinc on tissue delta-aminolevulinic acid dehydratase in urban pigeons.

1. Elevated lead burdens in three urban pigeon populations caused ALAD inhibition, in blood, kidney and liver, the degree of inhibition generally corresponding to the lead content of each tissue. The values obtained are compared with those given by studies of lead exposure in mammals. 2. The usefulness of blood ALAD as an index of lead exposure is discussed. 3. The pH activity profile of ALAD in blood and kidney of urban pigeons was also changed. 4. In vitro zinc additions partially restored lead-inhibited ALAD. 5. These findings are discussed in terms of the possible manner in which lead inhibits ALAD.