Tiered risk assessment of chemical pollution caused by military activities

The methodology of environmental risk is becoming more common to assess the impact of chemical pollution on human beings and the environment, providing information for making environmental remediation decisions. This article examines the impact on human health chemicals that penetrated into river water as a result of an accident at a military ammunition depot. The river is the source of drinking water for the population. Assessing the impact of chemicals on the health of adults, adolescents and children is carried out in stages (tiers), from simple to complex. Assessment is carried out both for carcinogenic and non-carcinogenic substances. The first tier is executed by a deterministic method – a method in which all biological, chemical, physical, and environmental parameters are assumed to be constant and can be accurately specified. Deterministic methods commonly apply to either a “most likely” value for a parameter, or a conservative value. When the obtained values are insufficient for making the decision, the second tier of a risk assessment begins. The values in this case have the form of probability distributions that determine their variability. Processing the risk model with the help of the one-dimensional Monte Carlo method gives more accurate data in the form of risk distribution. However, the method does not consider the lack of knowledge about the values of input variables, so, at the third tier of a risk assessment, the two-dimensional Monte Carlo method is used. In this case, the specified values of risk look like trend charts and indicate the limits of probability of risk for a certain percentage of the population