Forsøksdyr: Seafood safety of the pesticide pirimiphos methyl from plant-based feed ingredients in salmon aquafeed

Godkjenningsdato 17.09.2018

Godkjenningsperiode 17.09.2018-17.09.2019

The substitution of fishmeal and fish oil with plant-based raw materials has introduced novel contaminants such as agricultural pesticides into the aquatic food chain. Current regulations for pesticides are not yet adapted to fish feed or seafood, because of a lack of documentation on their safety.
The planned experiment aims to investigate seafood safety of pirimiphos-methyl, a plant-derived pesticide found in Atlantic salmon feed, using mice as a surrogate model for fish consumers. Salmon exposed to different levels of pirimiphos-methyl through their feed, will be used to prepare mice feed. The impact of both a possible transfer of pirimiphos-methyl and/or its metabolites from the fish fillet, as well as possible effects of a changed fillet composition on mouse health will be evaluated in a 90-day dietary exposure study.
The main aim of this study is the investigation of possible physiological effects following dietary pirimiphos-methyl exposure. Although the development of novel in vitro methods (f.ex. 3D cell culture techniques) has improved their accuracy modelling in vivo cellular responses to toxicants, it is not possible to assess systemic toxic or metabolic effects using in vitro methods. Thus, mice are considered the appropriate experimental model for the planned study.
The number of animals included is according to the official guidelines for testing of chemicals established by the Organization for Economic Co-Operation and Development (OECD), in order to assure quality and relevance of the obtained results for future risk assessment performed by national and international authorities. In order to reduce the number of animals, the planned experiment includes only female mice, which have been shown to be more sensitive to oral exposure in rats (Clapp and Conning, 1970), thereby cutting the number of animals used by half. In addition the utilisation of an inbred mouse strain (Balb/c) facilitates the use of a minimum number of animals required per experimental group according to the OECD guidelines (n=10 per experimental group; 45 animals in total).
Since the planned experiment is a toxicological study, a moderate stress will be imposed on the animals. However, at the highest doses included, we do not expect acute toxicity and harmful effects will thus be limited. In order to reduce stress and anxiety arising from handling, a refined handling technique will be implemented.
The findings of the planned experiment will contribute with relevant knowledge for future risk assessment of pirimiphos-methyl and its metabolites present in fish fillet. The results are thereby expected to assist the establishment of appropriate feed, imum residue limits for pirimiphos-methyl in fish fillet and fish feed, which ensures production of safe and healthy food.