New possibilities of the Ames test for evaluation of mutagenicity of technical products of active ingredients of pesticides

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Abstract

Introduction. The Ames test is the one of the most popular methods for mutagenicity evaluation of environmental factors. In some cases, this method is suggested to be the only and sufficient assay for the first stage of the equivalence assessment of pesticide technical grade active ingredients (TGAI) to the original products. A limitation of the Ames test is related to the impossibility of an objective equivalence assessment of some cytotoxic TGAIs, in particular, sulfonylureas, and triazolpyrimidines. Based on the mode of action of the pesticides belongs to these chemical classes, we suggested a modification of the plate incorporation method protocol of the Ames test to the increase of maximal non-cytotoxic concentration up to the 5 mg/plate recommended by regulatory documents.

Materials and methods. The five strains of Salmonella typhimurium ТА98, ТА100, ТА1535, ТА97, ТА102 were used. The modification of the protocol included a supplementation of the top agar with isoleucine (1–5 mM).

Results. The maximum non-cytotoxic concentrations of thifensulfuron-methyl and florasulam using the standard top agar did not exceed 0.05–0.125 mg/plate. The enrichment of the top agar with isoleucine allowed evaluating the mutagenicity of the substances up to the maximal recommended concentration of 5.0 mg/plate. The number of spontaneous revertants was within the historical limits of the laboratory control obtained under standard conditions. Positive controls showed pronounced mutagenic effects in case of all strains with and without metabolic activation (p≤0.05).

Limitations. Mutagenicity was evaluated only for TGAIs, which are acetohydroxyacid synthase inhibitors.

Conclusion. The application of the modified Ames test protocol for mutagenicity assessment of TGAIs from the classes of sulfonylureas and triazolpyrimidines under supplementation of the top agar with isoleucine is a more objective way to evaluate their mutagenicity. The proposed protocol expands the possibilities of revealing dangerous mutagenic impurities that may occur in TGAIs in the small quantities, and after entering the environment can cause the gain in the mutation level in living organisms.

Contribution:
Egorova O.V. — the concept and design of the study, the collection and processing of material, writing the text;
Ilyushina N.A. — statistical processing of the material, text editing.
All authors are responsible for the integrity of all parts of the manuscript and approval of the manuscript final version. 

Conflict of interest. The authors declare no conflict of interest. 

Acknowledgement. The study had no sponsorship. 

Received: June 21, 2022 / Accepted: October 3, 2022 / Published: November 30, 2022 

About the authors

Olga V. Egorova

Federal Scientific Center of Hygiene named after F.F. Erisman of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing

Author for correspondence.
Email: egorovaov@fferisman.ru
ORCID iD: 0000-0003-4748-8771

MD, PhD, senior researcher of the department of genetic toxicology, F.F. Erisman Federal Scientific Center of Hygiene of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing, Mytishchi, 141014, Russian Federation.

e-mail: egorovaov@fferisman.ru

Russian Federation

Natalia A. Ilyushina

Federal Scientific Center of Hygiene named after F.F. Erisman of the Federal Service for Surveillance on Consumer Rights Protection and Human Wellbeing

Email: noemail@neicon.ru
ORCID iD: 0000-0001-9122-9465
Russian Federation

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