Carcinogenic effects of 7,12-dimethylbenz[a]anthracene on the guppy ( Poecilia reticulata)

The carcinogenic effects of 7,12-dimethylbenz[ a]anthracene (DMBA) on the king cobra strain of guppy ( Poecilia reticulata) were examined. Specimens were exposed for 6 h once weekly for 4 wk to DMBA. Guppies were 6–11 days old at the initial exposure. Treatment groups included the following: (1) unt...

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Bibliographic Details
Published in:Aquatic toxicology 1989, Vol.15 (1), p.63-82
Main Authors: Hawkins, William E., Walker, William W., Lytle, Julia S., Lytle, Thomas F., Overstreet, Robin M.
Format: Article
Language:English
Subjects:
7,12-Dimethylbenz[ a]anthracene
Biological and medical sciences
Carcinogenesis
Environmental pollutants toxicology
Fish
Freshwater
Histopathology
Medical sciences
Neoplasm
Poecilia reticulata
Polycyclic aromatic hydrocarbon
Toxicology
Water
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Summary:The carcinogenic effects of 7,12-dimethylbenz[ a]anthracene (DMBA) on the king cobra strain of guppy ( Poecilia reticulata) were examined. Specimens were exposed for 6 h once weekly for 4 wk to DMBA. Guppies were 6–11 days old at the initial exposure. Treatment groups included the following: (1) untreated control; (2) dimethylformamide (DMF) carrier control; (3) low, water-mediated DMBA concentration (about 1–3 μg/l or ppb DMBA); (4) intermediate, DMF-mediated DMBA concentration (about 20 ppb DMBA); and (5) high, DMF-mediated DMBA concentration (about 35 ppb DMBA). Hepatic neoplasms developed in guppies exposed to the intermediate and high concentrations. Both of these exposure media contained the same concentrations of soluble DMBA. The high exposure medium, however, also contained an insoluble, particulate fraction of DMBA. Hepatic neoplasm incidences in fish exposed to the intermediate concentrations were 10% at 24 wk and 19% at 37 weeks after the initial exposure. In samples from the high concentration group, 47% had hepatic neoplasms at 24 weeks and 46% at 37 wk. Histologically, the hepatic lesions were categorized as altered foci, hepatocellular adenomas, and hepatocellular carcinomas. In addition to liver neoplasms, several other types of lesions developed in DMBA-exposed guppies. These included two undifferentiated sarcomas, a rhabdomyosarcoma, a renal adenocarcinoma, and a neurilemmoma. Only one control specimen (representing 0.38% of all controls) had a neoplastic lesion, a small hepatocellular adenoma in a 37-wk specimen. This study demonstrates that the guppy develops hepatic and extrahepatic neoplasms rapidly following brief water-borne exposures to those rather low levels of DMBA. Furthermore, the study showed that the particulate fraction of DMBA contributes to the carcinogenicity of the compound.
ISSN:0166-445X
1879-1514
DOI:10.1016/0166-445X(89)90006-4