Urinary excretion of lead and δ-aminolevulinic acid in workers occupationally exposed to tetraethyl lead

Forty-nine refinery workers and 50 motor mechanics were selected and examined for total lead (PbT), inorganic lead (PbI), and δ-aminolevulinic acid (ALA) in urine. The worker groups were exposed to tetraethyl lead (TEL) mainly by inhalation, but motor mechanics received additional exposure by skin because of hand cleansing with gasoline. The levels of urinary ALA (ALA-U) and urinary PbT (PbT-U) in refinery workers and motor mechanics were found to be significantly higher than the control group (p<0.05). The correlation between the ALA-U and PbT-U was found significant in both worker groups (p<0.001); however, relatively higher positive correlation was found between ALA-U and urinary inorganic lead (PbI-U) in TEL-exposed workers.