Lead contents in the surface enamel of deciduous teeth sampled in vivo from children in uncontaminated and in lead-contaminated areas

This study aimed to: (1) measure lead contents in the surface enamel of two populations consisting of 4-6-year-old children, one from an apparently uncontaminated area (Ribeirao Preto, Sao Paulo State, SP, Brazil, n = 247) and the other from an area notoriously contaminated with lead (Bauru, Sao Paulo State, Brazil, n = 26); (2) compare biopsy depths between the two populations; (3) correlate biopsy depth with lead content; (4) stratify samples according to biopsy depth to compare lead contents in samples from similar biopsy depths. A surface enamel acid-etch microbiopsy was performed in vivo on a single upper deciduous incisor for each sample. Lead was measured by graphite furnace atomic absorption spectrometry (GFAAS) while phosphorus was measured colorimetrically to establish biopsy depth. Samples from both populations were classified into categories of similar biopsy depths based on biopsy depth quartiles. Median lead contents were statistically different between the Ribeirao Preto population (206 mu g/g, range: 5-1399 mu g/g) and the Bauru population (786 mu g/g, range: 320-4711 mu g/g) (p < 0.001); however, biopsy depth did not differ between the Ribeirao Preto (3.9 mu m, Standard Deviation, SD = 0.9) and Bauru (3.8 mu m, SD = 0.9) populations (p = 0.7940). Pearson's correlation coefficient for biopsy depths versus logo lead values was -0.29 for Ribeirao Preto and -0.18 for Bauru. Lead contents were statistically different between the two populations for all quartiles of biopsy depth. These findings suggest that lead accumulated in the surface enamel of deciduous teeth is linked to the environment in which people reside, indicating that this tissue should be further explored as an accessible biomarker of lead exposure104333734