[In vivo evaluation of the level of lead in human superficial enamel using a double biopsy].

Two successive acid etch biopsies were performed on the permanent maxillary right central incisors of two age groups of children resident in an urban area in Belgium. Lead was determined in the biopsy solutions and the concentrations were related to etch depths, which were calculated from the calcium and phosphorus concentrations in the biopsy solutions. The mean lead concentration in the first enamel biopsy layer was five times higher than in the second biopsy. A strong correlation was observed between the two biopsies. It was shown that calibration of the lead values with respect to etch depths and Ca/P ratio was desirable and that a robust regression analysis approach was needed instead of classical more reliable calibration. In this study no age related increase in the surface enamel lead concentration could be demonstrated. Therefore, it was concluded that for these children the presence of lead in surface enamel had to be attributed primarily to pre-eruptive uptake.