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

The hypothesis that environmental lead exposure measured from blood (Pb-B) inhibits delta-aminolevulinic acid dehydratase activity (ALA-D) from whole blood was tested in 241 urban mothers and their newborns. Geometric means a nd (5th and 95th Percentiles) for maternal and cord Pb-B were 6.4 mu g dl(- 1) (3.4-11.9) and 4.6 mu g dl(-1) (2.8-9.2). Spearman correlations between mother and cord Pb-B and ALA-D were all negative but statistically signific ant only for cord Pb-B and mother ALA-D. A potential lead threshold, was id entified between 3.2 and 4.8 mu g dl(-1), above which ALA-D may be inhibite d by lead, and below which ALA-D may be insensitive or even activated. In c onclusion, low environmental exposure to lead is responsible for a demonstr able biochemical effect. This potential ALA-D inhibition may lead to neurot oxic effects, especially in newborns who have high level of neurogenesis. ( C) 1999 Elsevier Science Ireland Ltd. All rights reserved.