Modeling of waterborne chemicals exposure with substitution of insignificant values of concentrations

Objective. To scientifically substantiate methodological approaches to modeling of chronic exposure to chemicals with drinking water, taking into account the substitution of insignificant values of concentrations obtained in laboratory testing.

Materials and methods. Exposure calculation and health risk assessment for 6 variants of substitution of concentrations insignificant values were carried out, the specific contribution of substituted insignificant values to the formation of the final values of risk parameters was analyzed based on the results of laboratory tests of drinking water samples at 3 pilot water pipelines.

Results. Under different modeling variants, the contribution of surrogate values to the formation of the summation factor ranged from 8.5% to 89.3%, the hazard index ranged form 1.9% to 63.3%, the combined risk of chronic nonspecific toxic effects – from 1.9% to 59.5%, and the individual total carcinogenic risk – from 46.7% to 100%.

Conclusion. The sensitivity of research methods has a significant impact on the quality of assessments of public health risk from exposure to environmental risk factors. When assessing exposure to a complex of potential contaminants in drinking water, it is essential to use a differentiated approach to exposure modeling, taking into account 4 basic criteria for the substitution of insignificant values of concentrations: the sensitivity of the research method and the proportion of samples with quantitative determination, the risk profile of the contaminant (carcinogenic potential, ability to cumulate, remote effects) and its priority for the study area (based on the long-term profile of environmental risks and trends). Algorithm for the substitution of insignificant concentration values, taking into account the existing water use conditions in the country has been proposed and tested. Its application will rationally improve methodological approaches to chronic exposure assessment, avoid significant overestimation of exposure levels without reducing the quality and reliability of health risk assessments. Furthermore, it will allow us to concentrate measures to minimize health risks on the most priority aspects.

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