Cover title

"NPS-OR-92-012."

"May 1992."

AD A252 844

Includes bibliographical references (p. 18-19)

A histopathologic examination of tissues from Oryzias laptipes (Japanese medaka fish) was performed to evaluate the carcinogenic potential of tricholoroethylene (TCE) in groundwater. The data were reported by Experimental Pathology Laboratories, Inc., in a report dated Jan. 19, 1990, submitted to the Army Biomedical Research and Development Laboratory, Ft. Detrick, MD. This paper provides a brief statistical analysis of some aspects of those data. The analysis does not reveal a strong positive relationship between TCE concentration over the range considered and probability (risk or hazard) of incurring at least one end point manifestation (here cystic degeneration or liver neoplasm) in a fish. Uncertainties in the point estimates are assessed by bootstrapping. Both non-parametric (weak statistical assumptions) and parametric (stronger statistical assumptions) analyses give similar inconclusive dose- response indications. A brief discussion is included of a biologically-based mathematical model that is likely to form an appropriate basis for more sophisticated data analysis. One contribution of this paper is to discuss and illustrate techniques for quantitative analysis of other similar data. The methods can also be used to assist in choosing an experimental design. Binomial Distribution; Censored data; Generalized linear model; Bootstrap

aq/aq cc:9116 07/08/97

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