Influence of physicochemical parameters on the microtox test response

Abstract

Toxicity studies are generally conducted with single chemicals under standardized conditions. Yet results with the same substances can be different if antagonistic or synergistic interactions occur with the test medium constituents. In fact the toxic response of various chemicals seems highly dependent on temperature, contact time, salinity, buffering substances and water hardness.As Microtox test has previously been used to assess the toxicity of pure chemicals and complex effuents, it is interesting to study how some physico‐chemical interactions can modulate the response of the luminescent bacteria in this system.In the present investigation, the effects of the test temperature and the role of pH, buffers, hardness and salinity were studied for different times of exposure of the Microtox bacterial reagent to various inorganic and organic compounds including cadmium, zinc, pentachlorophenol and benzene. The results indicated that physicochemical parameters must be considered when analyzing Microtox data of complex effuents or mixtures of chemicals.