乳歯鉛濃度に関する衛生学的研究 特に環境汚染との関係について

Abstract

It has been noted by some investigators that lead is present in enamel and dentin of deciduous teeth, but there are no data on lead levels in deciduous teeth in Japanese.It was reported that most air pollution in the past was caused by exhaust gas from motor vehicles and lead levels in air were very high in large cities. As a result, tetraethyl lead has been restricted as a gasoline additive since 1975 in Japan. We present an investigation of lead levels in decidous teeth, which are considered greatly influenced by lead. We have tried to find out how lead levels in enamel and dentin of deciduous teeth in Tokyo change among two groups of children of different birth generations. Lead levels were determined by Zeeman effect flameless atomic absorption spectrometry.The results were as follows:1) Since the restriction of tetraethyl lead as a gasoline additive was put into practice, lead levels in enamel of deciduous teeth in Tokyo have been reduced. The geometric mean of lead levels in enamel of deciduous teeth from the group born in 1976-1980 (1.03μg/g) was significantly lower than in the other group born in 1962-1965 (3.08μg/g). There was a reduction of 79.4% in deciduous incisors, 61.9% in canines, and 59.0% in molars.2) Lead levels in dentin of deciduous teeth in Tokyo have also been reduced. The geometric mean of lead levels in dentin of deciduous teeth from the group born in 1976-1980 (1.27μg/g) was significantly lower than in the other group born in 1962-1965 (3.37μg/g). There was a reduction of 71.1% in deciduous incisors, 46.1% in canines, and 58.3% in molars.3) Significant correlation was observed between the lead in enamel and dentin of decidious teeth.4) This indicates that lead absorption in a body is marking a decline after starting the restriction.