A quantitative approach for integrating multiple lines of evidence for the evaluation of environmental health risks

Abstract

Decision analysis often considers multiple lines of evidence during the decision making process. Researchers and government agencies have advocated for quantitative weight-of-evidence approaches in which multiple lines of evidence can be considered when estimating risk. Therefore, we utilized Bayesian Markov Chain Monte Carlo to integrate several human-health risk assessment, biomonitoring, and epidemiology studies that have been conducted for two common insecticides (malathion and permethrin) used for adult mosquito management to generate an overall estimate of risk quotient (RQ). The utility of the Bayesian inference for risk management is that the estimated risk represents a probability distribution from which the probability of exceeding a threshold can be estimated. The mean RQs after all studies were incorporated were 0.4386, with a variance of 0.0163 for malathion and 0.3281 with a variance of 0.0083 for permethrin. After taking into account all of the evidence available on the risks of ULV insecticides, the probability that malathion or permethrin would exceed a level of concern was less than 0.0001. Bayesian estimates can substantially improve decisions by allowing decision makers to estimate the probability that a risk will exceed a level of concern by considering seemingly disparate lines of evidence.

Guidance on the use of the weight of evidence approach in scientific assessments

“…Publication Definitions or descriptions given for weight of evidence NRC (2009) States that 'The phrase weight of evidence is used by EPA and other scientific bodies to describe the strength of the scientific inferences that can be drawn from a given body of evidence'. Lorenz et al (2013) Defines 'weight of evidence framework' as 'approaches that have been developed for taking the process from scoping an assessment and initial identification of relevant studies through the drawing of appropriate conclusions' Schleier et al (2015) Describes weight of evidence as 'approaches in which multiple lines of evidence can be considered when estimating risk' Suter and Cormier (2011) 'In sum, weighing evidence is a synthetic process that combines the information content of multiple weighted pieces of evidence. The information may be dichotomous (supports or not), quantitative values (e.g., an exposure or risk estimate), qualitative properties (e.g., large, medium or small), or a model.…”

Quantifying Uncertainty in Ecotoxicological Risk Assessment: MUST, a Modular Uncertainty Scoring Tool

“…Despite the absence of systematic consideration of uncertainty in risk-based decisions, there exist qualitative and quantitative approaches suitable for this purpose. In toxicology, they range from methods with narrow foci on variability in individual data quality to complex statistical frameworks that combine multiple lines of (diverse) evidence to inform a risk-based decision. ,− Complex statistical frameworks, such as those relying on Bayesian logic or Dempster–Shafer theory, have a proven track record in toxicology. ,, However, a simpler approach that captures magnitude and diversity of available data and easily integrates into existing workflows of the (non-statistician) risk assessor may be preferred in certain applications, for example, in fast processing of raw (big) data.…”