Combined toxicity effects of MTBE and pesticides measured with Vibrio fischeri and Daphnia magna bioassays

Abstract

Methyl-tert-butyl ether (MTBE), a fuel oxygenate that is added to gasoline, commonly contaminates aquatic systems, many of which are already contaminated with pesticides. The toxic effects (EC 50 value) of several pure pesticides (Diuron, Linuron, Dichlofluanid, Sea nine, Irgarol and tributyltin (TBT)) were measured and compared with the EC 50 value of the pesticide mixed with MTBE, using the Vibrio fischeri and Daphnia magna acute toxicity assays. The interaction between chemicals was evaluated in terms of the effects of mixing on the EC 50 value (i.e. the concentration (mg/L) of a compound or mixture that is required to produce a 50% change in a toxic response parameter) and the time required to generate the toxic response. Presence of MTBE enhanced the EC 50 value of several pesticides (Diuron, Dichlofluanid, TBT and Linuron) and/or the toxic response manifested more rapidly than with pure pesticides. Toxicity enhancements were quite substantial in many cases. For example, the presence of MTBE increased the toxicity of Diuron by more than 50% when tested with the V. fischeri assay (5, 15 and 30 min exposure). Also, the toxic response manifested itself within 5 min whereas without the MTBE the same response arose in 30 min. Presence of MTBE increased the toxicity of Dichlofluanid by 30% when measured with the D. magna assay. Toxicities of only two pesticides (Sea nine and Irgarol) were not raised by the presence of MTBE. r

Toxicities of triclosan, phenol, and copper sulfate in activated sludge

“…Thus, at 0.582 6 0.024 d À1 , the BOD k value for the DMSO control was statistically identical to a k value of 0.6256 6 0.0421 d À1 determined for the wastewater controls. Similar results for DMSO were previously reported (Hernando et al, 2003).…”

Effect of Ultraviolet Light on the Efficiency of Nano Photo-Catalyst (UV/ CNTs/TiO2) Composite in Removing MTBE from Contaminated Water

“…MTBE has been found to raise the toxic effects of other pollutants in the environment, particularly pesticides [5]. The main concern however is with its potential adverse human health effects, symptoms of which include headache, cough, nausea dizziness and skin irritation [6].…”

Water Toxicity Monitoring using Optical Oxygen Sensing and Respirometry

“…cell based assays (42), due to significant variation in animal size and embryonic development of organs (MC-LR may influence liver cells differently at different development stages, and liver can metabolise the toxin differently). To generate statistically reliable data, we therefore used higher number of replicates (8)(9)(10)(11)(12). Loading Danio rerio in Luxcel plates was also a bit cumbersome.…”