Fluoride Action Network


BACKGROUND/AIMS: We investigated the combined toxic effect of sodium fluoride (NaF) and sulfur dioxide (SO2) on kidney morphological changes and DNA damage in male Wistar rats.

METHODS: In this study we selected totally 96 male Wistar rats (12-week-old) then randomly group-housed them into four cages, treated with deionized water, NaF, SO2 and co-treatment of NaF and SO2 respectively. Morphological changes of kidney were detected by hematoxylin and eosin (H&E) staining at 2, 4, 6 and 8 weeks. Correspondingly, tailing ratio and comet length were measured by BAB Bs Comet Assay System, including DNA damage special unit were calculated to evaluate the grades of kidney DNA damage at the same time.

RESULTS: Treated groups showed a body weight decrease when compared to control group. However, no significant difference in the relative weight of kidney was found in all four groups. It is noteworthy that at 2, 4, 6 and 8 weeks after exposure, the morphological alteration of renal tubules were observed in all treated groups, especially in group-IV. Also, at 4 and 6 weeks, notable DNA damage was found in all treated groups, as assessed by significantly increasing trend of comet length tailing ratio.

CONCLUSION: The study manifests that presence of NaF and SO2 will not only induce renal tissue lesions but also impact DNA integrity. In addition, this combined exposure exhibits a synergistic effect, characterizing a dose-dependence and time correlation. These findings may provide novel insights regarding perturbations of DNA damage and its functions as a potential new mechanism, by which cautious interpretation of NaF and SO2 co-exposure evolved in both animals and human beings is necessary.