A cross-sectional study was performed to evaluate associations between lead biomarkers, lead-related symptoms, and δ-aminolevuinic acid dethydratase (ALAD) genotype among 598 lead workers and 144 control office workers in storage battery industries, secondary smelting and litharge making industries. Lead inhibits the second enzymes, AlAD, in the heme synthesis pathway. ALAD gene, which codes for one of three isozymic proteins (termed ALAD1-1, ALAD1-2, and ALAD2-2), seems to modify the toxicokinetics of lead. The result as follows;
The percents of total workers whose genotype of ALAD1-1 and ALAD1-2 were 88.4％ and 11.6％, respectively. The zinprotoporphyrin in blood (ZPP) and δ-aminolevulinic acid in urine (ALAU) of lead workers with ALAD1-2 were signi-ficantly lower than those of lead workers with ALAD1-1, but there were no significant difference between two genotype for blood lead, age, and work duration.
The proportion of ALAD1-2 genotype in control office workers was 13.2％ . The proportions of ALAD1-2 genotype of lead workers were 14.0％(their mean air lead level below 0.024㎎/㎥), 10.4％(0.025-0.049㎎/㎥), 11.8％(0.050-0.099㎎/㎥), and 9.4％(above 0.100㎎/㎥), respectively.
In the logistic analysis of 15 lead related symptoms, ´arthralgia´(S7) symptom of ALAD1-2 was significantly lower(Or=0.481; 95% CI=0.248-0.932) than that of ALAD1-1, but ´feeling of irritation´(S11) of ALAD1-2 was significantly higher(OR=1.636; 95% CI=1.035-2.586) than that of ALAD1-1 after controlling possible confounder (blood lead, work duration, smoking and drinking habit).
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