Introduction. 2,2-Dimethoxy-2-phenylacetophenone is a widely used photoinitiator applied in various industries, including the production of varnishes, paints, dental materials, and coatings. However, despite its widespread use, the toxicological properties of this compound remain to be insufficiently studied.

The aim of this study. To investigate the toxicity and potential hazards of 2,2-dimethoxy-2-phenylacetophenone.

Materials and methods. Toxicological studies were conducted to assess the effects of the substance on warm-blooded animals. The experiments included evaluation of acute toxicity via oral, dermal, and inhalation exposure routes; evaluation of cumulative properties; assessment of irritation effects on the mucous membranes of the eyes and intact skin; as well as dermal resorptive and sensitizing effects.

Results. The study showed 2,2-dimethoxy-2-phenylacetophenone to belong to hazard class 4 (low hazard substances) when administered orally (DL50 > 5000 mg/kg). In acute dermal exposure tests, no animal mortality was observed (DL50 for rats > 2500 mg/kg). The substance does not exhibit skin irritant properties but can cause irritation to the mucous membranes of the eyes. No dermal resorptive effect was detected. The substance is not an allergen and does not exhibit cumulative properties. 2,2-Dimethoxy-2-phenylacetophenone is characterized by low volatility. During the study of acute inhalation toxicity, the maximum attainable concentration was 500 mg/m³. Therefore, the substance can be classified as moderately hazardous by the inhalation route of exposure.

Limitations. Due to the low volatility of 2,2-dimethoxy-2-phenylacetophenone and the technical limitations of the inhalation system, the study of acute inhalation toxicity was conducted at only one concentration.

Conclusion. The results of the toxicological studies indicate 2,2-dimethoxy-2-phenylacetophenone to belong to hazard class III (moderately hazardous substances). Considering its widespread use, presence in industrial emissions, and the consequent exposure risk to populations living near such facilities, further studies are recommended to evaluate its chronic toxicity, long-term effects, and carcinogenic potential.

Compliance with ethical standards. The study was conducted in accordance with generally accepted ethical guidelines for the use of laboratory animals and was approved by the Bioethics Committee of the Centre for Strategic Planning of the Centre for Strategic Planning of the Federal medical and biological agency, (meeting protocol No. 5 dated 09/18/2024).

Contribution: Fedotova L.A. – study concept and design, editing; Mamonov R.A. – study concept and design, editing; Pechnikova I.A. – study concept and design, collection and processing of material; Lebed-Sharlevich Ya.I. – writing text and data analysis, collection and processing of material; Manaeva E.S. – writing text and data analysis, collection and processing of material; Potapchenko T.D. – writing text and data analysis, collection and processing of material; Belyaeva N.I. – collection and processing of material; Gollandtseva A.I. – collection and processing of material; Nemtseva Yu.S. – collection and processing of material; Tyurina I.A. – collection and processing of material; Fedortsova D.Yu. – collection and processing of material; Fedortsov I.A. – collection and processing of material; Bolekhan V.N. – 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.

Funding. The study had no sponsorship.

Received: April 22, 2025 / Revised: August 6, 2025 / Accepted: December 2, 2025 / Published: January 15, 2026