Mitsuko Yamashita

A possible correlation between environmental chemicals and pigment cell neoplasia in fish

A croaker (Nibea mitsukurii) has a high incidence of the skin melanoma, chromatophoroma, in a Pacific coastal area in Japan. A sea catfish (Plotosus anguillaris) bearing skin melanosis is also found in the same area. For elucidation of a correlation between these pigment cell neoplasms of the skin and environmental contaminants, an epidemiological survey was conducted to determine the distribution and prevalence of tumor-bearing fish. Based upon observations of a high prevalence of skin neoplasms near the discharge point for kraft pulp mills, experiments were conducted to determine the neoplastic induction efficiency of the effluent on the croaker and sea catfish species. Isolation and identification of mutagens in effluent extracts were carried out using the Ames test, followed by mass spectral analysis of mutagenic fractions. The effluent induced a chromatophoroma on one croaker of the 100 tested, and it induced pigment cell hyperplasia on 70 to 100% of the sea catfish. These skin neoplasms were grossly similar to those observed in the field. Five chloroacetones were identified from the Ames-positive fractions of the effluent, and tetrachlorocyclopentene-1,3-dione and two alpha-dicarbonyl compounds were also detected as mutagens. The above experiments indicate that the mutagenic contaminants found in kraft mill effluent may play an important role in the induction of skin neoplastic disease in fish.

Effects of pH and temperature on the degradation of chloroacetones that are mutagenic

Recently, several reports on the mutagenicity of the mill effluents from paper and pulp industries have been published. The compounds were isolated and identified as mutagens from the spent chlorination liquors at the bleaching stage in the industries. Some of them might be released through a drainage-pipe into the river and/or the coastal sea water. But the fate of these compounds in the aquatic environment is little known in the literature. In this paper, the authors report the degradation efficiency of three mutagenic chloroacetones: 1,3-dichloroacetone, pentachloroacetone and hexachloroacetone, in a buffer solution. They also describe their degradation efficiency in the environmental waters at different pH and temperatures with and without sun-light.