Methodical approaches to assessing additional disease risk and loss of life expectancy at birth upon combined exposure to pollutants

Assessment of health risks and resulting negative health outcomes, including those caused by combined exposure to pollutants, as well as scientific substantiation provided for decisions aimed at managing them, are among priority hygienic tasks solved by Rospotrebnadzor through implementing its functions and powers. In this study, we were interested in developing methodical approaches to assessing additional disease risk and losses of life expectancy at birth upon combined exposure to pollutants. The study design is based on an iteration algorithm, which includes a cascade model of interrelated events Exposure - Biomarker of Exposure - Biomarker of Negative Effect - Negative Outcome (Disease) - Additional Health Risk. Probable losses of life expectancy at birth were predicted based on quantitative estimation of additional risk to isolated risk. We assessed approximately 300 multifactorial models (1000 parameters). The algorithm was tested for actual repeated exposure to airborne copper oxides in a concentration equal to 1.5-3.0 RfC; nickel oxides, 0.5-8.0 RfC; and chromium oxides, 0.2-3.9 RfC. The testing involved using the results obtained by our own long-term profound examinations accomplished over 2014-2023 with 2800 participants, of them 1868 children (aged 4-7 years) and 920 adults (aged 18-59 years). A predominantly synergic type was established for combined effects produced by copper, nickel and chromium oxides (up to 57.1 % cases). It created an additional risk to isolated disease risk, which was 1.5-6.4 times higher than its acceptable level. Additional health risk for children was caused by diseases of the nervous system; for adults, diseases of the circulatory system, metabolic disorders, and diseases of the nervous system. Probable losses of life expectancy at birth, given the existing additional health risks upon actual combined exposure to copper, nickel and chromium oxides, were equal to approximately one month (30.2 days) under the best-case scenario and approximately one year (376.0 days) under the worst-case one. Practical use of the proposed algorithm for assessing additional health risks upon combined exposure to chemicals makes it possible to perform objective analysis as regards the existing sanitary-hygienic situation, to achieve more effective and adequate assessment of the current and planned air protection activities for their timely adjustment, as well as to provide targeted medical and preventive measures until health risks decline down to their acceptable levels. At the same time, it is necessary to improve approaches to substantiating lists of chemicals that are top priority for regulation upon combined exposure to their mixture. It will help create a convincing basis for differentiation of regulatory measures and concentration of efforts on the highest health risks and health harm.