Improving Weight of Evidence Approaches to Chemical Evaluations

Abstract

Federal and other regulatory agencies often use or claim to use a weight of evidence (WoE) approach in chemical evaluation. Their approaches to the use of WoE, however, differ significantly, rely heavily on subjective professional judgment, and merit improvement. We review uses of WoE approaches in key articles in the peer-reviewed scientific literature, and find significant variations. We find that a hypothesis-based WoE approach, developed by Lorenz Rhomberg et al., can provide a stronger scientific basis for chemical assessment while improving transparency and preserving the appropriate scope of professional judgment. Their approach, while still evolving, relies on the explicit specification of the hypothesized basis for using the information at hand to infer the ability of an agent to cause human health impacts or, more broadly, affect other endpoints of concern. We describe and endorse such a hypothesis-based WoE approach to chemical evaluation.

Glyphosate toxicity and carcinogenicity: a review of the scientific basis of the European Union assessment and its differences with IARC

“…False positives and false negatives should both be considered, weighing the evidence (Lutter et al 2015; Rhomberg 2015a, b; Rhomberg et al 2013) and assessing specifically human relevance; and linked to the MTD concept, the relevance of toxicity-induced carcinogenic effects observed in experimental animals only at very high doses. The UN-GHS, and therefore, the EU CLP approach are based on UN harmonised criteria for weighing the evidence from rodent studies.…”

Quantitative weight of evidence assessment of higher-tier studies on the toxicity and risks of neonicotinoid insecticides in honeybees 1: Methods

“…Different scientific disciplines have adopted different methods for developing, analyzing, and integrating data, and combining information (Gough 2007), and this provides a challenge in a complex multidisciplinary area such as environmental risk assessment. Hypothesis-based approaches have been used for assessing risks of substances with endocrine activity (Borgert et al 2011(Borgert et al , 2014, carcinogens (Rhomberg, Bailey, and Goodman 2010), and chemicals in general (Lutter et al 2015). Quantitative and semiquantitative methods have been used for sediment (Chapman 2007), oil spills (McDonald et al 2007), for the herbicide atrazine (Van Der Kraak et al 2014), and for other chemicals (Bridges and Solomon 2016).…”

Systematic Reviews for Occupational Safety and Health Questions: Resources for Evidence Synthesis

“…Weight-of-evidence analyses are routinely used in ecological and human health risk assessments to collate heterogeneous information and to justify regulatory benchmarks and recommendations (Occupational Safety and Health Administration, 2012). However, the term is defined and used in a variety of ways, it often describes a methodological approach to interpret and evaluate data without further explanation, and there is no agreed-upon approach across scientific communities using the term (Krimsky, 2005;Weed, 2005;Lutter et al, 2015). Stakeholders have pointed out that, while a weight-of-evidence evaluation generally appeals to logic and the scientific process, how it is implemented in practice is less clear (Cormier, 2011).…”