In reviews on the carcinogenicity of N-nitroso compounds (NC) the number of animal species in which these compounds induce cancer is understated. In recent years additional species have been used in experiments. Tumours have been induced by NC in 39 species which belong to 36 genera, 25 families, 17 orders and five class of animals. The names of these taxa are presented in Latin and the common names of species are given in English, French and German. The carcinogenic action of eight NC in various species is tabulated.

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This study involved 34960 specimens of deepwater redfish, Sebastes mentella (Travin), from the North Atlantic, 21 460 of them from the Irminger Sea. One hundred and three specimens of this species, 96 with pigmented lesions, were examined histologically. The black patches on the redfish skin proved to be superficial melanosis (48 cases) and deep melanosis (24 cases). Skin ptcrinophorosis was noted in 20 eases. Pigment tissue neoplasms were observed in 26 fish; all were benign chromatoblastomas. Fourteen tumours were diagnosed as melanomas originating from melanophores, seven as pterinophoromas originating from pterinophores, and five as pterino-melanophoromas or melano-pterinophoromas of mixed origin of both chromatophore types. The tumours on the trunk of redfish occurred only in pigmented areas larger than 20 cm". Fish with such areas constitute no more than 2 4% of the total Irminger Sea redfish population. Most (76-2%) of pigmented lesions in this redfish population did not exceed 5 cm* in area. The arrangement of pigmented areas differed in males and females. In females, 97% of patches were found between the pectoral and the first dorsal fins, whilst in males, 84% of patches were situated on the head and caudal fin. Pigmented lesions occurred 2 -5 times more often in females than males. The causes of pigment tissue neoplasms and pigmented lesions in deepwater redfish arc unknown.

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