Lead content of deciduous tooth enamel from a high-radon area

Lead concentrations in the enamel of deciduous incisors of 49 6- to 7-year-old children living in Askola, a rural area in which the radon level is one of the highest in Finland, were determined by the proton-induced X-ray emission method. The absolute concentrations were obtained by calibration with the animal bone standard of the International Atomic Energy Agency. The mean lead concentration of 8.8 +/- 6.6 ppm of the whole enamel agreed well with the earlier corresponding lead data from other regions of Finland, indicating that no significant increase in the lead level of the teeth would have occurred because of radon decay. However, the lead concentration level measured on the tooth surface was somewhat higher in Askola, 232 +/- 141 ppm, than in the low-radon area Oulu (167 +/- 139 ppm; p less than 0.10). The lead concentration of the whole enamel of the upper incisors, 12.4 +/- 8.0 ppm, was twice as high as that of the lower incisors, 6.8 +/- 4.6 ppm (p less than 0.005), emphasizing the importance of classifying lead concentration data by tooth type.