Isotope ratios of lead in Japanese women's hair of the twentieth century

Isotope ratios of lead (Pb-207/Pb-206 and Pb-208/Pb-206) in Japanese women's hair of the twentieth century were measured to evaluate lead contamination of human proximate environment of those days. The historic hair samples (n = 40) were collected in 1980s by staffs of Department of Human Ecology, University of Tokyo, from Japanese women who cut their hair in 1910s to 1968 by themselves for hair piece or needle pad and who had stored it by the time of collection. Additional five contemporary hair samples (one from male and four from females) were also included. The hair samples were digested with HNO3, diluted with water to Pb concentration of 10 A mu g/kg, and isotope ratios were measured by inductively coupled plasma mass spectrometry. Isotope ratios as well as Pb concentration in the hair samples of the twentieth century varied to a considerable extent depending on the period of hair cut. The oldest hair samples (1910-1920s) had the highest concentration and the most distinct isotope ratios from those of Japanese domestic Pb indicating serious contamination of proximate environment of people of those days with Pb originated from mines in other regions of the world, probably through the usage of Pb-containing face powder. The concentration and isotope ratios of Pb decreased thereafter indicating less serious contamination of proximate environment of Japanese which, in turn, should have affected by environmental contamination of mid-twentieth century due to industrial activities and leaded gasoline. Contemporary Pb level was quite low (< 1 mg/kg); however, isotope ratios were close to those in 1960s when hair concentration was assumed to be strongly affected by leaded gasoline.