The feasibility of using rat liver mitochondria respiratory parameters as a short-term toxicity test was investigated. Mitochondrial fractions were exposed to six concentrations of five chlorophenols. Respiratory parameters were measured and compared to control experiments. The toxicity of the chlorophenos, measured by the 50% uncoupling concentration (UC50), increased with increasing chloro substitution. The UC50 values for the five chlorophenols were compared to six physicochemical parameters for the same chlorophenols and high degrees of correlation were found (r >/- 0.890). The highest correlation coefficient obtained was with the octanol-water partition coefficient. UC50 values were also compared to nine currently existing short-term toxicity tests. High degrees of correlation were obtained with several of these tests, including bacterial and fish bioassays. From the results of these experiments, the measurement and use of mitochondria respiratory parameters as a short-term toxicity test appears to offer an alternative to currently used short-term toxicity tests, particularly with chemicals having physicochemical characteristics similar to mitochondria uncouplers. / Master of Science