Fig. 4. Variation of toxicity (ph adjusted samples), ph and absorbance in time during the decoloration of 2000 mg L^–1 amaranth by trametes versicolor. Bda = before dye addition. Ada = after dye addition. Toxicity calculated for the 50% effect and 15 minutes exposure time (tu50, 15 min) as 100/ec50. Three measurements/mean and 95% confidence level.