Exposure to lead exacerbates dental fluorosis.
Department of Morphology, Stomatology and Physiology, School of Dentistry of Ribeirao Preto, University of Sao Paulo (FORP/USP), Avenida do Café, S/N, 14040-904 Ribeirao Preto, SP, Brazil.
Our aim was to test the hypothesis that co-exposure to lead and fluoride alter the severity of enamel fluorosis.
MATERIALS AND METHODS:
Wistar rats were allocated in four groups: control, and 3 groups that received water containing 100 ppm of fluoride (F), 30 ppm of lead (Pb), or 100 ppm of F and 30 ppm of Pb (F+Pb) from the beginning of gestation. Enamel analysis and F and Pb determinations in enamel, dentine, and bone were performed in 81-day-old animals. Fluorosis was quantified using a new fluorosis index based on the identification of incisor enamel defects (white bands and white islets, representing hypomineralization, and cavities) weighted according to their severity and quantity. Hypomineralization was validated histopathologically by polarizing microscopy and microradiography. Scores were given by two blinded calibrated examiners (intra and interexaminer kappa values were 0.8 and 0.86, respectively).
The control and the Pb groups presented normal enamel. The F+Pb group presented more severe enamel defects compared with the F group (P<0.0001).
This study shows that lead exacerbates dental fluorosis in rodents, suggesting that co-exposure to lead may affect the degree of fluorosis.
Fluoride increases lead concentrations in whole blood and in calcified tissues from lead-exposed rats.
Toxicology. 2010 Apr 30;271(1-2):21-6. Epub 2010 Feb 25.
School of Dentistry of Ribeirao Preto, University of Sao Paulo (FORP/USP), Av do Café s/n, 14040-904, Ribeirão Preto, SP, Brazil.
Higher blood lead (BPb) levels have been reported in children living in communities that receive fluoride-treated water. Here, we examined whether fluoride co-administered with lead increases BPb and lead concentrations in calcified tissues in Wistar rats exposed to this metal from the beginning of gestation. We exposed female rats and their offspring to control water (Control Group), 100mg/L of fluoride (F Group), 30mg/L of lead (Pb Group), or 100mg/L of fluoride and 30mg/L of lead (F+Pb Group) from 1 week prior to mating until offspring was 81 days old. Blood and calcified tissues (enamel, dentine, and bone) were harvested at day 81 for lead and fluoride analyses. Higher BPb concentrations were found in the F+Pb Group compared with the Pb Group (76.7+/-11.0microg/dL vs. 22.6+/-8.5microg/dL, respectively; p<0.001). Two- to threefold higher lead concentrations were found in the calcified tissues in the F+Pb Group compared with the Pb Group (all p<0.001). Fluoride concentrations were similar in the F and in the F+Pb Groups. These findings show that fluoride consistently increases BPb and calcified tissues Pb concentrations in animals exposed to low levels of lead and suggest that a biological effect not yet recognized may underlie the epidemiological association between increased BPb lead levels in children living in water-fluoridated communities.