Comparison of Blood Lead and Blood and Plasma δ-Aminolevulinic Acid Concentrations as Biomarkers for Lead Poisoning in Cattle

Abstract

Lead (Pb) concentrations in whole blood and δ-aminolevulinic acid (ALA) concentrations in plasma and whole blood from 37 cattle with suspected Pb exposure were determined in order to investigate the usefulness of ALA as a biological indicator for Pb poisoning in cattle. Cows were divided into 4 groups based on blood Pb, as follows: <30 ppb (group 1), 30–100 ppb (group 2), 100–300 ppb (group 3), and >300 ppb (group 4). The derivatization reaction for ALA was improved by a greater than 2-fold measure in whole blood and by a 10-fold measure in plasma by adding 75 and 50 μl of 0.1 N HCl, respectively. Blood Pb concentrations ranged from <25 ppb to 1,006 ppb (185.5 ± 254.9 ppb), with 17 samples containing >50 ppb Pb. Delta-aminolevulinic acid concentrations in whole blood and plasma ranged from <62.7 ppb to 96.9 ppb (77.4 ± 8.4 ppb) and from <5.0 ppb to 24.0 ppb (4.6 ± 3.8 ppb), respectively. Whole blood ALA did not correlate with blood lead concentrations in any group. Increase in plasma ALA concentration was dependent on blood Pb concentration. There was no correlation between blood Pb concentration and plasma ALA concentration in group 2 ( n = 4), but correlation coefficients were 0.736 in group 3 and 0.807 in group 4, respectively. The correlation coefficient was increased to 0.851 when groups 3 and 4 were combined. Based on these observations, in cattle, plasma ALA is a more reliable biological biomarker for Pb exposure than is blood ALA.