exposure status, smoking and alcohol drinking, were significantly associated with ICL and time-weighted ICL. Regression analyses suggested that exposure status and personal habits (smoking and alcohol drinking) are still the major effects on blood lead parameters for lead workers rather than genotypes. In conclusion, VDR genotypes did not significantly affect the long term blood lead parameters after adjustment for all factors, but industrial hygiene improvement, including engineering control and health education, are the most important ways to protect workers' health. Blood lead levels or even bone lead levels would not always explain workers' health status, because individual susceptibility to lead toxicity may play an important role in lead toxicology and physiology. For example, lead inhibition of zinc metalloenzyme, delta-aminolevulinate dehydratase (ALAD), is one of the most sensitive indicators of blood lead levels. Previous studies have suggested that polymorphism in delta-ALAD, a heme synthetic enzyme, may be associated with differences in blood lead levels, perhaps due to different binding of lead in erythrocytes 1, 2) . Moreover, the toxicological relationship in which lead affects calcium and vitamin D metabolism had not been well understood. The biological interactions between lead and calcium are complex 3) . Some studies suggested that variant VDR alleles modify lead concentrations in bone, either by influencing lead content or calcium content or both 4) . We have been following up a group of lead workers for 12 yr. Although some studies had been done on personal hygiene habits 5) and health effects 6) , we cannot