Further studies on toxaphene in fish feed

Fish are sensitive to waterborne toxaphene, but relatively little is known about the way fish respond to toxaphene in fish feed. Through a 3-year project entitled "Toxicological evaluation of toxaphene in fish feed", researchers from Radboud University Nijmegen (the Netherlands), the University of Plymouth (UK), the Norwegian Institute of Marine Research and the National Institute of Nutrition and Seafood Research will study the toxicity of toxaphene in fish feed.  

"We will examine how efficiently the fish take up various forms of toxaphene from fish feed. This is important in relation to food safety and upper limits for undesirable substances in fish feed. It is also important to examine which levels of toxaphene in fish feed that can affect fish health", says researcher Erik-Jan Lock on the Seafood Safety Research Programme at NIFES

Toxaphene is accumulated in the food chain where it is broken down and is found in more than 200 different forms (congeners).Knowledge regarding the dietary toxicity of the different forms of toxaphene is insufficient.  

"The EU's maximum limit for toxaphene in feed are based on knowledge regarding three of the 200 forms. In our studies, we will include an additional five forms of toxaphene that have been detected in fish. Cell models enables us to study the toxicity of these forms individually and in combination, and will form the basis for feeding trials with fish", says Lock.

"The results of these studies are important for conductinga scientifically sound risk assessment  of toxaphene in fish feed", says Lock.

The production of the pesticide toxaphene started in 1945. In the 1970s it replaced the use of DDT in many parts of the world, but its use as a pesticide has been banned since 2004 . Toxaphene is a persistent and lipid-soluble chemical that accumulates in the aquatic food chain; including pelagic fish from which fish oils are produced.. The EU has set an upper limit for toxaphene in most animal feeds of 0.1 mg/kg, wherasthe upper limits  for fish oil, fish meal  and fish feed are 0.2 mg/kg, 0.02 mg/kg and 0.05 mg/kg, respectively.