Comparison between males and females with respect to the porphyrin metabolic disorders found in workers occupationally exposed to lead.

To elucidate the sex difference in porphyrin metabolic disorders induced by lead exposure, we determined plasma delta-aminolevulinic acid (ALA), urinary ALA, and urinary coproporphyrin (CP) in 298 lead-exposed workers (160 males and 138 females), and compared the data thus obtained. The use of fluorometric high-performance liquid chromatography (HPLC) method which is highly sensitive and specific made possible the measurement of ALA in a small volume (50 microliters) of plasma. The concentrations (mean +/- SD) of lead in blood (males: 55.1 +/- 12.9 micrograms/dl; females: 54.7 +/- 13.5 micrograms/dl) indicated that the intensity of occupational exposure to lead was almost equal in the two groups. However, the elevation of plasma ALA concentration and the increased urine ALA and CP excretion among these lead workers were much higher in females than in males, confirming the finding of a sex difference in the biological effect of human exposure. The difference in urine CP excretion was especially pronounced, the mean concentration of urinary CP in the female workers being 3.5-5 times higher than that in the male workers.