Dose-response relationship between tobacco consumption and melanin pigmentation in the attached gingiva

The dose response relationship between tobacco consumption and melanin pigmentation in the attached gingiva was examined on two occasions 4 years apart in a group of Japanese lead workers with blood lead concentrations below 2.0 mu mol/kg (40 micrograms/100 g). In the two examinations, 12% and 18% of the total group of workers and 17% and 24% of the smokers had melanin pigmentation. The prevalence of pigmentation was significantly higher in smokers who inhaled more than 10 cigarettes per day (17% and 25%) than in nonsmokers (0% and 2%), and tended to increase significantly with tobacco consumption. Lead absorption was not associated with melanin pigmentation.