Toxicity of pesticides in wastewater: a comparative assessment of rapid bioassays

Acute toxicity of pesticides in water was assessed singly and in mixtures u sing various responses of the luminescent bacterium Vibrio fischeri, the aq uatic invertebrate Daphnia magna, and the MitoScan(TM) assay. The latter ut ilized fragmented mitochondria to enzymatically convert oxidized beta -nico tinamide adenine dinucleotide (NAD(+)) to its reduced form, NADH. The rate of the conversion being sensitive to the type and concentration of toxicant s. The pesticides tested were carbofuran, cyromazine, fenamiphos, formetana te, and propamocarb. The aqueous solubility of all compounds exceeded 320 m g l(-1). All the toxicity bioassays were characterized in terms of relative sensitivity and complementarity. Synergistic and antagonistic toxicity eff ects were observed with pesticide cocktails relative to pure compound toxic ities. The D. magna assay was the most sensitive and best able to detect to xic interactions of mixtures. Cyromazine was the least toxic of the pestici des tested. (C) 2001 Elsevier Science B.V. All rights reserved.