Effects of bensulfuron-methyl and cinosulfuron on growth of four freshwater species of phytoplankton.
The acute toxicity of sulfonylurea herbicides bensulfuron-methyl and cinosulfuron was tested on the five species of freshwater phytoplankton: Scenedesmus acutus, Scenedesmus subspicatus, Chlorella vulgaris and Chlorella saccharophila. Herbicide concentrations eliciting a 50% growth reduction over 96 h (EC50) ranged from 8 to 104 mg/l for cinosulfuron and from 0.015 to 6.2 mg/l for bensulfuron-methyl. The pesticides bensulfuron-methyl, atrazine and benthiocarb were more toxic than cinosulfuron, chlorsulfuron, molinate, fenitrothion and pyridaphenthion in a toxicity study with the same algal species. The transformation of effective concentrations of bensulfuron-methyl and cinosulfuron and other pesticides, obtained from toxicity measurements, into percent of the saturation level in water is used as a first evaluation of potential hazard to aquatic systems. The herbicides cinosulfuron, methyl-bensulfuron, atrazine and chlorsulfuron were more dangerous than the herbicides benthiocarb and molinate and than the insecticides fenitrothion and pyridaphenthion, in a study of hazard evaluation. The two species of Chlorella were more tolerant to both herbicides than the two species of Scenedesmus. A potential environmental hazard of sulfonylurea herbicides to aquatic systems has to be expected even at low environmental concentrations.
Sabater
C
C
Department of Biotechnology, E.T.S.I.A., Polytechnic University of Valencia, Spain. csabater@btc.upv.es
Cuesta
A
A
Carrasco
R
R
D004781:Environmental Exposure; D006540:Herbicides / Q000633:toxicity*; D007928:Lethal Dose 50; D010839:Phytoplankton; D018570:Risk Assessment; D013453:Sulfonylurea Compounds / Q000633:toxicity*; D000096926:Benzenesulfonamides
D006540:Herbicides; D013453:Sulfonylurea Compounds; C469574:cinosulfuron; D000096926:Benzenesulfonamides; C071475:methyl bensulfuron