Lead in prehistoric, historic and contemporary Japanese: stable isotopic study by ICP mass spectrometry Jun Yoshinaga*, Minoru Yoneda, Masatoshi Morita and Tsuguyoshi Suzuki National Institute for Environmental Studies, 16-2 Onogawa, Tsukuba, Ibaraki 305, Japan (Received 4 March 1997; accepted in revised form 30 December 1997) AbstractÐLead concentration and isotopic composition of prehistoric (middle and latest Jomon era, 2000±4500 BP, n = 6), historic (Edo era, 130±400 BP, n = 10), and contemporary (died in 1987±88, n = 15) Japanese bones, and deciduous teeth from contemporary Japanese children born during 1985± 88 (n = 17) were analyzed by inductively coupled plasma mass spectrometry. Lead concentration was lowest in Jomon bones and was higher in rural Edo, contemporary, and urban Edo, in that order. Elev- ated Pb concentration in historic Edo people, as reported previously, was recon®rmed. The average iso- topic ratios ( 207 Pb/ 206 Pb and 208 Pb/ 206 Pb) in excavated (prehistoric and historic) bones, contemporary bones, and deciduous teeth were dierent from each other. The contemporary bones had the least radiogenic composition (mean 207 Pb/ 206 Pb: 0.879; mean 208 Pb/ 206 Pb: 2.126) while the excavated bones the most (0.848; 2.098), and teeth intermediate (0.866; 2.111). The comparison with the literature data of isotopic compositions of environmental samples showed that the isotopic composition of the exca- vated bones was within the range of Japanese ores, rocks and soils, indicating the absence of foreign Pb sources in preindustrialized Japan. That of the contemporary bones was closer to the average gaso- line Pb, the use of which had been banned in the late 1970s, than to the Pb in airborne particulate mat- ter or refuse incineration ash of 1980s. The average Pb isotopic ratios in the deciduous teeth was close to the isotopic ratios of Pb in airborne particulate matter and refuse incineration ash. These data indi- cated that the contemporary Japanese population was exposed to foreign Pb which had dierent isoto- pic composition from domestic Pb. Exposure to Pb of foreign origin was particularly evidently recorded in people born before the leaded gasoline ban. The history of human Pb contamination in Japan is discussed based on the present results and other previously published data. # 1998 Elsevier Science Ltd. All rights reserved INTRODUCTION Lead is a typical environmental pollutant and its dynamics in the environment, such as transport, distribution and elimination, have long been a mat- ter of concern. One of the typical approaches to study the dynamics of Pb has been to measure Pb concentrations in compartments of the environment to estimate a relative distribution among them. Another approach is the use of stable isotope ratios to trace the fate of Pb in the environment. The natural abundance of 4 stable isotopes of Pb, i.e., 204 Pb, 206 Pb, 207 Pb and 208 Pb, is variable depending on its source (ore). The abundance in the source Pb passes to the Pb in any products manufactured from the source like a ``®ngerprint''. Therefore, iso- topic ratios of Pb can be used as a naturally occur- ring tracer for the analysis of the environmental fate of Pb. Lead isotope analysis has been successfully applied to the estimation of the anthropogenic bur- den to the natural Pb in an ecosystem and the con- tributions of dierent anthropogenic sources (e.g., Rabinowitz and Wetherill, 1973; Stukas and Wong, 1981; Gulson et al., 1981; Boutron and Patterson, 1987; Flegal et al., 1989; Gulson et al., 1994) as well as the temporal trend in Pb pollution sources (e.g., Chow et al., 1973; Shirahata et al., 1980; Rosman et al., 1993; Shotyk et al., 1996; Graney et al., 1997). The chronological studies are of particu- lar importance in evaluating when and how Pb pol- lution began to pose an impact on the environment and in predicting the future trend. There are two isotopic studies to trace the historic trend of Pb pol- lution in Japan: analysis of tree rings by Murozumi et al. (1982) and that of sediment cores by Hirao et al. (1986). The results of the two studies agreed that Pb concentrations in the samples started to increase in the early 20th century and this was accompanied by isotopic alteration. The authors attributed this trend to the introduction of imported foreign Pb, that had a distinct isotopic composition from the domestic Pb, after industrialization had started in Japan. On the other hand, analyses of excavated human bones revealed elevated Pb concentrations in preindustrialized Japanese historic era, Edo (400± 130 BP) (Kosugi et al., 1986, 1988; Hisanaga et al., Applied Geochemistry, Vol. 13, pp. 403±413, 1998 # 1998 Elsevier Science Ltd All rights reserved. Printed in Great Britain 0883-2927/98 $19.00 + 0.00 PII: S0883-2927(98)00004-3 *Corresponding author. 403