Ranking the Relative Importance of Toxicological Observations Based on Subject Matter Expertise

<p>Toxicological investigations provide key observations for establishing potential impacts of chemicals and other materials in environmental exposures. The specific evaluation of chemical toxicity can be drawn from numerous lines of evidence, including, but, not limited to: lethality, sub-lethal impacts, toxicokinetics, critical tissue residues, molecular toxicology, reproductive impacts, mutation, carcinogenesis, decreased genetic diversity in populations and decreased species diversity. Despite this richness of potential observations, many predictive toxicological models, such as those included in life cycle impact assessment (LCIA), generally rely on one or a few ecotoxicity measures including median lethal concentrations (LC50) and no observed effects concentrations (NOECs). By excluding all but these composite effects metrics, such models often fail to accurately and/or robustly capture potential adverse outcomes that may negatively affect individual health, biological fitness and/or population sustainability. Although each has the potential to add value to chemical risk assessment, the relative importance of the various toxicological observations available for characterizing and assessing environmental impact has not been established. Therefore, we sought to establish the importance of multiple ecotoxicological lines of evidence for assessing environmental impacts. “Importance” in this context is a subjective valuation based on perceived utility within an assessment, therefore we developed and administered a survey to query subject matter experts (SMEs) in the fields of toxicology, ecotoxicology and risk assessment on the importance of a broad array of ecotoxicological measurements. This scoping study focused on SME opinions from Department of Defense scientists and risk assessors where 61 surveys were distributed and 21 returned and analyzed. Overall, observations from chronic exposures and reproductive endpoints were ranked the highest among SMEs while lines of evidence from in vivo studies outranked both in vitro and in silico observations.</p