Hepatic alterations and induction of micronuclei in rainbow trout Oncorhynchus mykiss exposed to a textile industry effluent

Abstract

Rainbow trout, Oncorhynchus mykiss, were exposed to a sublethal dose of a wool shrinkproofing effluent for 15, 30, 45 and 60 days. Liver and blood samples were taken after the exposure time together with samples of control handled fish. A light and electron microscope study was carried out to evaluate the histopathological lesions induced in the liver of treated fish. The genotoxic potential of the effluent was assessed by piscine micronucleus test. Vacuolation of liver bile preductular cells was observed in all exposed fish; abnormal lipid accumulation and basophilic foci were seen in the liver of one 30-days- and one 45-days-exposed fish, respectively. These specific alterations could be related to a pre-carcinogenic process. On the contrary, other lesions also described in all treated fish such as dilatation, vesiculation and degranulation of the rough endoplasmic reticulum, altered mitochondria, increase in myelin bodies and lysosomes and presence of phagosomes in wandering macrophages might be considered as non-specific alterations, similar to those described in fish exposed to different pollutants. Frequencies of micronucleated peripheral erythrocytes showed a significant increase following 30-days exposure.