The Substitution Principle - Uncertainty in risk-risk consideration and decision making in the case of substituting Thiacloprid with Tau-fluvalinate

Abstract: The “Substitution Principle” gives the direction to substitute hazardous substances to less dangerous ones when possible. The idea of substituting substances to less dangerous alternatives is currently of concern and the “Substitution Principle” is one of the tools used to do so. This has come into focus since polluted lakes, air and/or land areas has ended up as consequences of chemical emissions. For the substitution to be successful it needs to be preceded by consideration of the risk-risk tradeoff by the at the moment used chemical and its substitute. This study wants to show the problems when doing risk-risk tradeoffs under uncertainty and the challenge with this is illustrated with a case-study of the neonicotinoid Thiacloprid and a possible substitute, the pyrethroid Tau-fluvalinate. Different scenarios regarding the extent of substitution have been analyzed with respect to impact on freshwater and a hypothetical impact on pollinators. Estimated costs which are associated with these chemicals as well as the initial cost when doing a substitution have also been used as input. Impact score, that is how the substances affect the freshwater regarding toxicity which was derived from USEtox® assessment model, has been used to assess the impact of the two substances on freshwater. In this paper two treatments of uncertainty have been observed by applying two different decision theories, the “Expected Utility Theory” and the “Maximin Principle”. It is concluded that Tau-fluvalinate is not a proper substitute to Thiacloprid regarding its effect on freshwater ecosystems. Tau-fluvalinate is a lot more hazardous to freshwater organisms. The utility differs when different factors are considered, in this case impact on pollinators and/or initial cost. It also differs looking at the expected versus the maxmin utility. It can be concluded that the treatment of uncertainty in a risk-risk assessment affects which decisions will be made.