Toxicity of cypermethrin on growth, pigments, and superoxide dismutase of Scenedesmus obliquus.

Cypermethrin is a synthetic pyrethroid that is particularly toxic to crustaceans. It is therefore applied as a chemotherapeutant in farms for the treatment of pests. The effective concentrations of cypermethrin on the inhibition of Scenedesmus obliquus growth at 96 h (96 h EC50) were determined to be 50, 100, 150, 200, and 250 mg/L. Algal growth, pigment fractions, and the activity of superoxide dismutase (SOD) in the algal cells were measured in the exponential phase after exposure to cypermethrin. The results show that higher concentration of cypermethrin is inhibitory for growth and other metabolic activities and the 96 h EC50 of cypermethrin to S. obliquus is 112+/-9 mg/L; the potential application of SOD activity in S. obliquus as a sensitive biomarker for cypermethrin exposure is also discussed.