Abstract:

Purpose: To examine the acute toxicity and genotoxicity of gibberellin A3 (GA3), which can provide scientific
support for the reasonable use of GA3 and a reference for establishing maximum residue limit (MRL) for GA3. Methods:
Acute toxicity was examined by using the maximum tolerated dose method while genotoxicity was examined using Viciamicronucleus
test, bone marrow cell micronucleus test and sperm abnormality test in mice. Results: The acute oral LD50 of
GA3 in Kunming mice was > 15 000 mg/kg. As GA3 concentration increased from 0.1 to 2.0 mg/L, the micronucleus rate of
Vicia faba root tip cells showed a rising trend, which indicated a highly significant difference compared to negative controls
and the micronucleus index remained higher than 1.5 at all investigated GA3 concentrations. The bone marrow micronucleus
rates of male and female mice treated with 7.5 g/kg GA3 were 7.47‰ and 7.07‰, respectively, and the sperm malformation
rate of mice was 5.47%, which revealed highly significant differences compared to that of negative controls (P < 0.01).
Conclusion: Although GA3 with low acute toxicity can be considered as a non-toxic substance, it causes genotoxicity to plant
cells and animal somatic and germ cells at high doses. The MRL for GA3 should be set up as early as possible.

Key words: gibberellin A3, acute toxicity, genotoxicity