Diuron in water: Functional toxicity and intracellular detoxification patterns of active concentrations assayed in tandem by a yeast-based probe

A study on the acute and chronic effects of the herbicide diuron was carried out. The test, basing on a yeast cell probe, investigated the interference with cellular catabolism and possible self-detoxification capacity of Saccharomyces cerevisiae. Aerobic respiration was taken as the toxicological end-point. Percentage interference (%rho) with cellular respiration was measured in water by increased dissolved O-2 concentration (ppm) after exposure to different doses. Interference was calculated through the comparison of respiratory activity of exposed and non-exposed cells. Short-term and long-term (6 and 24 h respectively) exposures were also considered. The test for short-term exposure gave positive %rho values except that for 10(-6) M (11.11%, 11.76%, 13.33% and 0% for 10(-10) M, 10(-8) M, 10(-7) M and 10(-6) M respectively). In the case of long-term exposure the test showed positive %rho values, but less effect than short-term exposure until 10(-8) M and much higher at 10(-6) M (7.41%, 8.82%, 11.76% and 6.06% for 10(-10) M, 10(-8) M, 10(-7) M and 10(-6) M respectively). The findings of aerobic respiration as toxicological end-point were in agreement with known mechanisms of toxicity and intracellular detoxification for both the doses and exposure times employed.