Toxicological characterization of the insecticide metofluthrin and assessment of the carcinogenic risk to human health due to its chronic inhalation effect

The aim of the investigation is the toxicological characterization and analysis of the danger criteria of the insecticide metofluthrin with an assessment of the carcinogenic risk to health caused by chronic inhalation exposure to the substance at the level of the maximum possible concentrations in the air environment of human life. The analysis of scientific reports of the US Environmental Protection Agency (US EPA) and the European Chemicals Agency (ECHA) on the toxicological properties of metofluthrin was carried out. The assessment of the risk of the development of carcinogenic effects due to chronic inhalation exposure to metofluthrin was carried out taking into account the average daily dose of the substance that can enter the human body during the natural life span (LADD) and the carcinogenic potential factor (SF) in accordance with domestic guidelines. Classification of levels of carcinogenic risk was carried out using domestic and international approaches. It was established that the limiting criteria for the danger of metofluthrin are the average lethal concentration in air (LC50 =1080 mg/m³) and the size of the zone of chronic action (Zch=7.46), which characterizes the danger of occurrence of chronic intoxication due to long-term inhalation exposure. According to these indicators, metofluthrin is classified as a dangerous substance (hazard class 2). The key effects of the toxic action of metofluthrin are determined – neurotoxicity, hepatotoxicity and nephrotoxicity. The threshold non-genotoxic oncogenic potential of metofluthrin according to the phenobarbital type was established. Individual carcinogenic risk under different scenarios of chronic inhalation exposure to metofluthrin was calculated. The substance concentration of 3.54 mg/m³ leads to a high level of risk (1.5×10-3), which is considered unacceptable for production conditions and the population. At concentrations of 0.28 mg/m³ and 1.0 mg/m³, the risk is estimated as average and acceptable for production conditions (1.1-4.1×10-4). The risk of exposure to a concentration of 0.14 mg/m³ is classified as low and acceptable for the population (5.7×10-5). Thus, the results obtained in the study indicate that such concentrations of metofluthrin in the air as 0.14 – 0.28 – 1.0 mg/m³ are safe for human health, subject to compliance with medical and sanitary regulations at the stage of production and application of insecticides based on metofluthrin as prescribed.