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Toxicological evaluation of toxaphene in fish feed

Tildelt: kr 3,2 mill.

Toxaphene replaced DDT as the most heavily used pesticide in many parts of the world in the early 1970s. It is distinctively bio accumulated in aquatic biota, and considered to be a persistent organic pollutant in the sense of the Stockholm convention. Al though relatively non toxic to mammals, toxaphene is highly toxic to fish, hence its use as a piscicide in the past. Whereas the waterborne toxicity has been documented, no information is available on feed borne exposures and elimination kinetics of toxap hene in farmed fish. For food contaminants, acute toxicity is normally of little significance. More relevant are the sublethal adverse effects resulting from toxic concentrations fed over a longer exposure period. Crucial information on general fish healt h/performance after (low-dose) exposure and possible congener transformation and carry-over is lacking. This proposal aims to make a comparison between the use of molecular and biochemical biomarkers and other end-points of toxicity (e.g. pathology, haema tology, and growth) in short-term (months) dietary toxaphene toxicity studies and to establish NOAEL and LOAEL for (weathered) toxaphene in Atlantic salmon. Special focus on the kinetics of the congeners CHB 32, 40, 41, 42 and 44 will be given. A hepatocy te culture will be used to determine the genetic responses of exposure to different congeners. Recently, an alarming study of Kapp and colleagues (2006) on toxaphene toxicity using zebrafish embryos demonstrated that toxaphene is becoming more toxic durin g transformation in the environment. A decrease in the total amount of toxaphene during environmental breakdown would then be compensated for, at least in part, by the higher toxicity of weathered toxaphene in sediments, soils, and biota of contaminated e cosystems. It is therefore highly recommended to assess and evaluate the toxicity of (weathered) toxaphene (and its congeners) to farmed Atlantic salmon and to establish markers for early dietary toxicity.

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HAVBRUKS-Havbruk - en næring i vekst