Impact of radiation on nerves system incidence among the workers involved in mitigation of the Chernobyl accident

The radiological consequences of the accident at the Chernobyl nuclear power plant, which occurred in 1986, remain the focus of attention both in the scientific community and in various departments and organizations that ensure the radiological safety of citizens in the event of radiation accidents. The analysis of these radiological consequences is one of the main tasks of the National Radiation Epidemiological Registry (NRER). According to NRER, among participants in the liquidation of the consequences of the Chernobyl accident (liquidators), already in the first years after work in the accident zone, a significant increase in the incidence of most classes of diseases was noted. Diseases of the nervous system and sensory organs are among the top three in terms of growth rates. The purpose of this study is to quantitatively assess the radiation risks of liquidators suffering from diseases of the nervous system. Based on 38-year observations of a cohort of liquidators registered in the NRER, statistically significant estimates of the radiation risks of the incidence of diseases of the nervous system among liquidators obtained with an estimate of the excess relative risk coefficient (ERR/Gy=0.38), which, considering the confidence intervals of the estimates, is comparable to the level of radiation risk for solid cancers in the same cohort (ERR/Gy=0.69). Polyneuropathies and other lesions of the peripheral nervous system (G60-G64) with an ERR/Gy=0.93 coefficient, as well as other nervous system disorders (G90-G99) with an ERR/Gy=0.42 coefficient make the greatest contribution to the radiation risk of nervous system diseases. Nonparametric estimates of radiation risks in dose intervals and estimates of a linear-quadratic radiation risk model show that estimates in the form of the ERR/Gy coefficient, i.e. within the framework of a linear no-threshold model, in the region of low doses (up to 0.3 Gy) are underestimated, and the radiation effect in the form of an increase in the incidence of diseases of the nervous system may be threshold, which requires additional research. For most diseases of the central nervous system, radiation risks have not been detected. The influence of other previous diseases on the radiation risk of nervous system diseases is statistically insignificant, and assessment of the possible influence of nervous system diseases on the radiation risk of subsequent diseases from other classes of diseases requires additional research.