Zinc in primary teeth from children in Norway

Human primary teeth have been used as indicators of exposure to several hea vy metals both in Norway and elsewhere. Local dentists in all 19 counties o f Norway collected 2747 primary teeth during 1990-1994. Samples of tooth po wder from whole, ground teeth were analyzed for zinc concentration by flame atomic absorption spectrophotometry. The overall geometrical mean was 144. 5 mu g of Zn/g of tooth substance (S.D. = 1.6). The result represents a sma ll increase (5.2%) compared with a similar investigation in the 1970s. Howe ver, the mean zinc concentrations in the geographically matching parts of t he two materials did not differ significantly. The variation in tooth zinc concentrations between the different counties declined from the 1970s to th e 1990s. We found no correlation between the tooth zinc concentration and a vailable environmental data on zinc in drinking-water, discharge of zinc fr om industrial point sources or population density in the same geographical areas. The zinc concentrations varied significantly with caries status, too th type and root length. Few samples had a zinc concentration below 90 mu g /g, indicating that most children consume sufficient zinc. Some very high v alues could not immediately be explained, but may be caused by contaminatio n from zinc-containing dental restorations. (C) 1999 Elsevier Science B.V. All rights reserved.