Acute toxicity and DNA damage of fluoride to larval big toad Bufo gargarizans

Fluoride caused widespread endemic fluorosis in humans, but little attention was paid to the effect of fluoride on aquatic organisms. A standard method was used to evaluate the acute toxicity (96h) of fluoride on Bufo gargarizans tadpoles at Gosner stage 33. Toxicity symptoms of fluoride in B. gargarizans tadpoles included abnormal motility, loss of equilibrium and decompensation. Dose- and time-dependent increases in mortality rate were observed in response to the test fluoride. The 24h, 48h, 72h and 96h LC50 (median lethal concentration) of NaF to B. gargarizans tadpoles were 693.02 mg/L, 660.57 mg/L, 643.12 mg/L and 622.81 mg/L, respectively. The safe concentration (SC) of fluoride in water for larvae B. gargarizans was 6.2281 mg/L. Furthermore, the DNA damage caused by high-dose fluoride exposure was detected by DNA ladder. The results offered basic data to further research and highlighted the necessity of management of fluoride in water to protect aquatic animals.