The natural occurrence of trace metals in human teeth

Abstract

Up to the present, reports on trace heavy metals in teeth of Japanese are very scarce.The author described a method for the application of atomic absorption spectrophotometry to the determination of trace heavy metals (zinc, lead, copper and cadmium) in extracted human permanent teeth in the first report.This article reports on the level of Zn, Pb, Cu and Cd in extracted intact human permanent teeth from different geographic areas (Tokyo, Okitsu, Hachijo Island and Annaka) employing the analytical methods that were described in the first report.The results were as follows:(1) The mean values of metal concentrations of 99 samples were 198 μg/g Zn, 7.29 μg/g Pb, 1.48 μg/g Cu and 0.12 μg/g Cd on a basis of dry weight.(2) Distribution forms of the four metals in teeth were logarithmic-normal.(3) The concentrations of the four metals showed wide variation from tooth to tooth and according to geographic locality.(4) The mean concentration of Pb was highest in teeth collected from Tokyo (11.61 μg/g Pb) and lowest in teeth from Okitsu, a rural village (4.65 μg/g Pb).(5) The mean concentrations of Zn, Cu and Cd were highest in teeth collected from Hachijo Island. (269 μg/g Zn, 2.94 μg/g Cu, 0.43 μg/g Cd)(6) The data on Annaka samples indicated that teeth from the residents exposed to smoke of the Toho zinc smelting plant did not have a higher concentration of Cd and Zn than other regions (0.10 μg/g Cd, 186 μg/g Zn).(7) Significant correlations were observed between the Ca and Cu content, the Zn and Cu content, the Zn and Cd content and the Cu and Cd content at the 1% level of significance.