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Title: The development and application of an in vivo micronucleus assay to monitor chronic exposure of species to genotoxic chemicals in the aquatic environment
Author: Jones, C.
Awarding Body: University College of Swansea
Current Institution: Swansea University
Date of Award: 1995
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The ability of acute tests to reflect damage induced from continuous exposure to low concentrations of xenobiotics for a prominent part of an animals life span is speculative. The assessment of human risk from exposure to genotoxic chemicals in drinking water, of both agricultural and industrial origin, and from water purification processes, is one such example. An in vivo micronucleus assay has been developed for this purpose. The assay involved the exposure of the amphibian Xenopus laevis from embryo to late tadpole stage. Micronuclei frequencies were estimated from the erythrocyte population and mortality, development, growth and behaviour as well as subtle changes in erythrocyte cell cycle kinetics were additionally assessed. For comparative purposes, an in vitro micronucleus assay for a Xenopus kidney epithelial cell line was developed. Both assays were validated with four CEC suspected aneuploidy inducing compounds, namely hydroquinone, benlate, cadmium, chloride and thimerosal. The results compared well to those observed in mammalian micronucleus assays but some discordance was observed between the in vivo and in vitro results; explanations for the variability are provided. Confirmation of the sensitivity of the Xenopus assays was achieved by the investigation of water sampled from a chlorination and ozone treatment plant, from within the Severn Trent Water Authority catchment area. The results were compared to the established Salmonella Plate Incorporation Mutation assay and were highly comparable. In contrast to most assays, the in vivo assay was sufficiently sensitive that concentration of the water samples was not required. The in vivo assay also proved suitable for the detection of teratogens, the application of which was investigated. The in vivo assay presented in this study, therefore, examines a variety of endpoints and is highly superior to the toxicity assays presently used to monitor water quality.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available