Experimental substantiation of the risks of developing health disorders when exposed to smoke from wildfires

Abstract

Introduction. An increase in the number of wildfires, along with the lack of a chemical control system for the quality of the atmosphere during smoke, leads to a risk of developing health disorders for rescuers and firefighters exposed to high concentrations of toxic smoke components.
 The study aims to identify causal relationships based on experimental modeling between exposure to natural fire smoke and the functional state of the nervous and reproductive systems.
 Materials and methods. The authors conducted studies on white rats of both sexes. The animals were placed in inhalation chambers and exposed to forest fire smoke of varying concentrations and duration of exposure. The scientists examined the functional state of the nervous system (open field method, Morris test, electroencephalography, histology of nervous tissue), the reproductive system (number of Leydig cells, average number of spermatogonia, spermatogenesis index), the presence of genotoxicity (DNA comet method), DNA methylation and the effect on offspring (postnatal development, species-specific behavior). We calculated the total exposure limit in each group of animals in accordance with the indicators of CO and PM2.5 content in the chambers.
 Results. The researchers found that with a total exposure load of 0.03–0.22 mg, there were initial changes in the morphofunctional state of the central nervous system. With an increase in the load to 4 mg, violations of the indicators of behavior and electrical activity of the brain were accompanied by significant changes in the structure of the nervous tissue of the rat brain. The reproductive function of rats under the influence of smoke changed, starting with a total exposure dose of 10.8 mg. We observed a decrease in spermatogenesis and a change in the cyclic function of the ovaries. A violation of the postnatal development of offspring has already been detected with a total dose of 0.22 to 4 mg. Prolonged exposure to tobacco smoke for one month was accompanied by a pronounced violation of the spermatogenetic function of the testicles and an increase in neonatal mortality in offspring, as well as a violation of the structure of behavior and spatial memory in adulthood. The genotoxic effect of smoke was not detected, and a change in DNA methylation in blood cells was detected at the maximum total dose of smoke components.
 Limitation. The study is limited to studying the effect of wildfire smoke on the nervous and reproductive systems of mongrel white male rats.
 Conclusion. The results obtained are a fundamental foundation for solving such tasks as the development of risk-oriented preventive health-saving measures for workers in extreme situations in conditions of smoke during wildfires and making effective management decisions.
 Ethics. The study was approved by the local Ethics Committee of the East-Siberian Institute of Medical and Ecological Research (Protocol LK of East-Siberian Institute of Medical and Ecological Research No. 32/19 dated 09/10/2019), conducted in accordance with the European Convention for the Protection of Vertebrates Used for Experiments or Other Scientific Purposes (ETS No. 123), Directive of the European Parliament and the Council of the European Union 2010/63/EC dated 09/22/2010 on the protection of animals used for scientific purposes.