Evaluation of the effects of fluoride and associated with lead in animal model and physical-chemical analysis of public supply water and of the Sinos river in the South of Brazil

Abstract

Fluoride related to caries prevention is at the center of a scientific controversy. Studies show that fluoride causes damage to health and the environment, as well as reducing IQ in children. The fluoridation of drinking water, mandatory in Brazil, has repercussions over the whole society. One of our objectives was to know the concentrations of fluoride (F) and toxic metals of Sinos River, treated water and final consumers of the cities of Campo Bom (CB), Novo Hamburgo (NH) and São Leopoldo (SL), as well as the groundwater from Ivoti, located in southern Brazil. We also evaluated in rats the effects of F and, in association with lead (Pb), on thyroid hormones and the Total Antioxidant Capacity (TAC). Three groups of rats were exposed to different waters: G1-Control with distilled water (DW); G2-DW with 25ppm (F); G3-DW with 25ppm (F) + 30 ppm (Pb). The Sinos River has an average concentration of 0.0735 mg.L^-1 of F. But the F of both the water treated by the ETA of SL as well as in the final consumers of SL had concentrations above 0.9 mg.L^-1 (State Ordinance No. 10/1999). In addition, we verified the presence of Pb and Cr (VI) in all types of water. The results with the animals showed a significant difference in T3 (p=0.032) and in T4 (p=0.043) from G3 to G1. In TAC, the difference was significant from G2 to G1 and G3 (p=0.007), showing that F and F with Pb interfere with the endocrine and antioxidant functions of rats. In addition, the fact that there are water fluoridation failures shows that the population is exposed to health risks. We confirm that drinking water fluoridation needs to be demystified and reconsidered as a public health intervention.