Acute and 28-Day Repeated Dose Oral Toxicity Studies of Olaflur, a Common Cariostatic Agent in Children's Toothpaste

In recent years, olaflur, mainly containing three amine hydrofluorides (compounds 1-3), has been widely used as a cariostatic agent in children's toothpaste. However, there is no report on the systematic toxic evaluation of olaflur thus far. Therefore, acute and 28-day repeated dose oral toxicity studies of commercial olaflur and 1-3 were conducted in rats. Two inorganic fluorides, sodium fluoride (NaF) and sodium monofluorophosphate (SMFP), were selected as positive controls in the 28-day study. The acute oral LD₅₀ values were determined as 35.0, 28.3, 36.5, and 30.7 mg F/kg for commercial olaflur and 1-3, respectively, indicating higher toxicity than inorganic fluorides. In the 28-day study, olaflur and 1-3 primarily induced hepatic, splenic, pulmonary, and gastrointestinal toxicity. In particular, at doses of 4 and 10 mg F/kg, the spleen exhibited punctate necrosis and the duodenum and jejunum exhibited edema of the intestinal villi, whereas these toxic effects were not observed in all NaF/SMFP groups. Structural-toxicity analysis of these amine hydrofluorides and inorganic fluorides reveals that the protonated alkylamine moiety contributes significant additional gastrointestinal toxicity beyond the fluoride ion. These findings strongly urge caution in the use of olaflur and its constituents as dentifrice additives, particularly for children's toothpaste.