Biomonitoring lead exposure with delta-aminolevulinate dehydratase (ALA-D) activity ratios.

The occupational or environmental exposure of selected populations to lead, either alone or in combination with other metals, was monitored using ratios of the activity of the erythrocytic enzyme delta-aminolevulinate dehydratase. The results obtained have reaffirmed earlier findings that this test affords several significant advantages over the use of the enzyme's activity value measured at a set pH value and other types of activity ratios to assess lead exposure. Furthermore, the activity ratios' proven sensitivity, reliability, reproducibility, specificity and stability warrant that they be considered as viable alternatives to the more widely accepted diagnostic criteria of lead intoxication namely zinc protoporphyrin and lead levels in blood.