Toxicity assessment of a common laundry detergent using the freshwater flagellate Euglena gracilis

Abstract: Synthetic detergents are among the commonly used chemicals in everyday life. Detergents, reaching aquatic environments through domestic and municipal wastewater, can cause many different effects in aquatic organisms. The present study was aimed at the toxicity evaluation of a commonly used laundry detergent, Ariel, using the freshwater flagellate Euglena gracilis as a biotest organism. Different parameters of the flagellate like motility, swimming velocity, cell shape, gravitactic orientation, photosynthesis and concentration of light harvesting pigments were used as end points for the toxicity assessment. No Observed Effect Concentration (NOEC) and EC50 values were calculated for the end point parameters at four different incubation times, i.e. 0, 6, 24 and 72h. After 72h incubation, swimming velocity of the cells was found to be the most sensitive parameter giving NOEC and EC50 values of 10.8 and 34mgL−1, respectively. After 72h exposure to the detergent, chlorophyll a and total carotenoids were significantly decreased in cultures treated with Ariel at concentrations of 50mgL−1 and above while chlorophyll b significantly decreased at concentrations above 750mgL−1. The maximum inhibitory effect on the quantum yield of photosystem II was observed after 24h exposure and thereafter a recovery trend was observed. Motility, gravitaxis and cell shape were strongly impaired immediately upon exposure to the detergent, but with increasing exposure time these parameters showed acclimatization to the stress and thus the NOEC values obtained after 72h were higher than those immediately after exposure. [Copyright &y& Elsevier]