A Reference Value for Delta-Aminolevulinic Acid in Plasma in the Population Occupationally Unexposed to Lead

To obtain a reference value for delta-aminolevulinic acid in plasma (ALA-P), we determined ALA-P levels in 141 subjects (105 males and 36 females) without occupational exposure to lead. The distribution of ALA-P levels in males can be regarded to follow log-normal distribution and the geometric mean was 8.7μg/l with 95% confidence interval of 6.0-12.5μg/l. These data would be useful as a baseline for evaluating the relationship between ALA and its biological effects.