Human experts’ judgment of chemicals reactivity for identification of hazardous chemicals

The development of non-testing approaches for the identification of chemicals with the potential to cause environmental hazards, have gained increased attention. In this study the hypothesis that experts’ judgement of chemical reactivity could be used for this purpose has been tested. The judgments of chemical reactivity for 200 organic chemicals, based on their molecular structure were performed by four senior organic and environmental chemists. Potentials for reactivity (namely: oxidative/reductive reactivity, hydrolysis, direct photolysis, reactivity towards radicals) were scored on the 1– scale. Both the experts’ individual judgment, and a compromised judgment after joint discussion for clarification of cases with divergent opinions, was analysed. Furthermore we searched for relations between the expert judgement data and: (a) the chemical characteristics representedby 40 chemical descriptors using partial least squares regression (PLS), and (b) experimental and in silico data for different toxicological and physico-chemical end-points. The results of on-going analyses indicate that for the majority of the chemicals, the individual judgments differed significantly between experts but after discussion among the experts for clarification, the judgments becamemuch more concurrent. The relation between averaged experts’ predicted photolytic degradation potential and chemical characteristic based on a PLS model (with three significant components explaining 76% of the variation) was found. We have also found that in the group of the chemicals with the higher score of the experts judged oxidative reactivity there was higher percentage of biodegradable chemicals when compar