Characterizing Risk for Cumulative Risk Assessments

Abstract

In assessing environmental health risks, the risk characterization step synthesizes information gathered in evaluating exposures to stressors together with dose-response relationships, characteristics of the exposed population, and external environmental conditions. This article summarizes key steps of a cumulative risk assessment (CRA) followed by a discussion of considerations for characterizing cumulative risks. Cumulative risk characterizations differ considerably from single chemical- or single source-based risk characterization. CRAs typically focus on a specific population instead of a pollutant or pollutant source and should include an evaluation of all relevant sources contributing to the exposures in the population and other factors that influence dose-response relationships. Second, CRAs may include influential environmental and population-specific conditions, involving multiple chemical and nonchemical stressors. Third, a CRA could examine multiple health effects, reflecting joint toxicity and the potential for toxicological interactions. Fourth, the complexities often necessitate simplifying methods, including judgment-based and semi-quantitative indices that collapse disparate data into numerical scores. Fifth, because of the higher dimensionality and potentially large number of interactions, information needed to quantify risk is typically incomplete, necessitating an uncertainty analysis. Three approaches that could be used for characterizing risks in a CRA are presented: the multiroute hazard index, stressor grouping by exposure and toxicity, and indices for screening multiple factors and conditions. Other key roles of the risk characterization in CRAs are also described, mainly the translational aspect of including a characterization summary for lay readers (in addition to the technical analysis), and placing the results in the context of the likely risk-based decisions.

Cumulative risk assessment for combinations of environmental and psychosocial stressors: A systematic review

“…Cumulative risk assessment for combinations of environmental and psychosocial stressors is still at the early stages of exploration and development; the construction of theoretical models would help to establish the knowledge blueprint (Menzie et al, 2007). Based on this, the existing qualitative analyses mainly focus on the establishment and examination of theoretical models and analytic frameworks to identify stressors, pathways, exposure population, the protected object, and evaluation endpoints covered in risk assessment and also describe the relationships among them (MacDonell et al, 2018).…”

Association of the Built Environment With Childhood Psychosocial Stress

“…As described in cumulative risk frameworks, multiple stressors work together to induce disease and should be considered together. 26 For example, in a prospective cohort of schoolchildren, 27 green space was found to be associated with enhanced working memory and a reduction in inattentiveness, but the observed outcomes were partially mediated by elemental carbon air pollution exposure. To our knowledge, few other studies have taken a multiexposure approach in assessing mental health outcomes.…”

“…In addressing the environmental factors associated with children’s stress, a joint exposure approach enables a more comprehensive examination of the urban environment and the relative associations and potential synergisms of stressors. As described in cumulative risk frameworks, multiple stressors work together to induce disease and should be considered together . For example, in a prospective cohort of schoolchildren, green space was found to be associated with enhanced working memory and a reduction in inattentiveness, but the observed outcomes were partially mediated by elemental carbon air pollution exposure.…”