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 (%r) with cellular respiration was measured in water by increased dissolved O2 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 %r 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 %r 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.