Environmental lead exposure and activity of δ-aminolevulinic acid dehydratase (ALA-D) in maternal and cord blood

Abstract

The hypothesis that environmental lead exposure measured from blood (Pb-B) inhibits δ-aminolevulinic acid dehydratase activity (ALA-D) from whole blood was tested in 241 urban mothers and their newborns. Geometric means and (5th and 95th Percentiles) for maternal and cord Pb-B were 6.4 μg dl −1 (3.4–11.9) and 4.6 μg dl −1 (2.8–9.2). Spearman correlations between mother and cord Pb-B and ALA-D were all negative but statistically significant only for cord Pb-B and mother ALA-D. A potential lead threshold, was identified between 3.2 and 4.8 μg dl −1, above which ALA-D may be inhibited by lead, and below which ALA-D may be insensitive or even activated. In conclusion, low environmental exposure to lead is responsible for a demonstrable biochemical effect. This potential ALA-D inhibition may lead to neurotoxic effects, especially in newborns who have high level of neurogenesis.