title: Clastogenicity in vitro of the Na, K, Ca and Mg salts of saccharin; and of magnesium chloride; consideration of significance.
abstract: The sodium, potassium, calcium and magnesium salts of saccharin, and magnesium chloride, have been shown to be clastogenic to Chinese hamster lung (CHL) fibroblasts in vitro, but only at elevated dose levels (8-16 mg/ml). Saccharin acid was inactive to the limits of its solubility (4 mg/ml). When the data are expressed in terms of ionic concentration, each salt showed a similar clastogenic potency. This suggests that ionic effects induced by these salts in the assay medium may be the critical determinant of the clastogenic effects seen, rather than that the saccharin moiety presents a genotoxic insult to the chromosomes of the cells. The metal-chelating agents EDTA and EGTA were non-clastogenic, but the disodium salt of EDTA showed weak activity prior to toxicity at 0.5 mg/ml. The absence of a clastogenic response for the salts of saccharin at dose levels lower than 4 mg/ml is discussed within the context of the threshold-dependent tumour-promoting activity of high dose levels of sodium saccharin to the bladder of male rats. The doubtful value of conducting in vitro clastogenicity studies at dose levels greater than 10(-2) M is discussed.
mesh_terms: D000818:Animals; D002118:Calcium; D002478:Cells, Cultured; D002869:Chromosome Aberrations; D002875:Chromosomes / Q000187:drug effects*; D006224:Cricetinae; D004305:Dose-Response Relationship, Drug; D008274:Magnesium; D015636:Magnesium Chloride; D009154:Mutation / Q000187:drug effects*; D011188:Potassium; D012439:Saccharin / Q000633:toxicity*; D012492:Salts; D012964:Sodium
chemical_list: D012492:Salts; D015636:Magnesium Chloride; D012964:Sodium; D012439:Saccharin; D008274:Magnesium; D011188:Potassium; D002118:Calcium