delta-Aminolaevulinic acid dehydratase as an index of lead toxicity. Time for a reappraisal?

delta-Aminolaevulinic acid dehydratase activity is traditionally accepted as the most sensitive measurable biological index of lead toxicity. We have measured delta-aminolaevulinic acid dehydratase activity and blood lead concentration in 47 healthy controls (A), 42 iron deficient patients (B) and 38 occupationally exposed to lead subjects (C). Blood lead levels [mean (SD)] did not differ between groups A and B [0.51 (0.21) and 0.43 (0.19) mumol L-1, respectively] while those of group C [2.28 (0.56) mumol L-1 were significantly higher (P < 0.001) as compared to the controls. delta-Aminolaevulinic acid dehydratase activity [mean (SD)] was significantly increased [3599 (1909) mumol L-1 h-1] in group B and decreased in group C [1052 (532) mumol L-1 h-1] as compared to the controls [2034 (446) mumol L-1 h-1] (P < 0.001). There was a significantly negative correlation of logarithm of delta-aminolaevulinic acid dehydratase with lead in both groups B (P < 0.05) and C (P < 0.001) but not in group A (P = 0.1). delta-Aminolaevulinic acid dehydratase activity had a high specificity (100%) but a low sensitivity (37%) as an index of toxic lead exposure. According to our data the value of delta-aminolaevulinic acid dehydratase measurement in the diagnosis of lead intoxication is doubtful in cases with low blood lead levels, while in the presence of iron deficiency its reliability is further reduced, since low blood lead levels may be falsely predicted. delta-Aminolaevulinic acid dehydratase activity should be restricted only to monitoring cases with moderate or severe lead poisoning.

Lead exposure of the child population in Greece

Lead exposure of the child population was studied in three different areas in Greece: Kalamata which is a rural area of Southern Greece; Tavros, a district of Athens with a considerable industrial activity; and Lavrion, a small city near Athens where a lead-zinc mining and smelting industrial complex has existed for more than 90 years. The results were evaluated with respect to a number of individual, social and environmental variables (i.e. smelter, occupation of the father) especially those concerning the area of Lavrion which is the most heavily polluted area in Greece. The results of this study can be considered as an index for the extent of the lead pollution problem in the named areas of Greece.

Statistically significant hematopoietic effects of low blood lead levels

Blood lead (Pb-b) concentrations, hematocrit (Ht), and hemoglobin (Hb) were determined in three groups of men working in different parts of a cable-producing factory. All three parameters examined, i.e., Pb-b, Ht, and Hb, in the above groups were found to be within "normal" limits. However, within each group of men studied, there was a statistically significant negative correlation between Pb-b concentrations and Ht and Hb values. This finding indicates that any increase in Pb-b concentration, even within the "normal" values, may result in a decrease of hematocrit and hemoglobin values of the same subjects.