Summary

Description

The activity of the erythrocyte enzyme daminolevulinic acid dehydratase ALAD has long been used as a biomarker of lead exposure in humans and waterfowl and, more recently, in fishes. We tested the assay for ALAD activity in fishes from streams affected by lead in combination with other metals from leadzinc mining and related activities. Fishes mostly catostomids were collected from sites affected by historic and current mining activities, and from sites thought to be unaffected by mining reference sites. A suite of elements was measured in blood and carcass samples of individual fish and in grab samples of water and sediment from each site. ALAD activity, total protein IP, and hemoglobin Hb content also were determined in blood. Concentrations of miningrelated metals lead, zinc, and cadmium were significantly greater PO.O5 at sites affected by historic mining activities than at reference and active mining sites. ALAD activity, Hb, and TP accounted for 66 of bloodlead and 69 of carcasslead variability when analyzed by multiple regression. Differences among species were minimal. ALAD activity as a biomarker was able to successfully distinguish sites affected by bioavailable environmental lead and appeared to be unaffected by other metals except for zinc, which tended to arneliorate the inactivation of ALAD by lead. The utility of the biomarker lies in its expedience and its ability to document bioavailability.