Assessment of Toxic Interactions of Heavy Metals in Binary Mixtures: A Statistical Approach

Abstract

Toxicity of zinc, copper, cobalt, and chromium ions and their binary interactions were studied at varying test levels by using a battery of two tests, Microtox and duckweed with Vibrio fisheri and Lemna minor as test organisms, respectively. The type of toxic interaction at each test combination was assessed by a statistical approach based on testing the null hypothesis of "additive toxicity" at 95% confidence level. The interactions were called "antagonistic," "additive," or "synergistic" in accordance with the statistical significance and the sign of the difference between the tested hypothesis and the value of the observed toxicity at the binary test level concerned. In the majority of the combinations studied by the two bioassays, the interactions were of antagonistic nature. Additive toxicity was the next frequently predicted interaction in both test results, the frequency being much higher in Microtox responses than in those of duckweed. Finally, synergism was found to be a rare interaction in Microtox results, but totally unlikely in duckweed within the selected test combinations.

Zinc-Induced Genotoxic Effects in Root Meristems of Barley Seedlings

“…Contrasting and inconclusive data on the genotoxicity of Zn compounds are available in literature. The observations recorded on several herbaceous and woody species showed differentiated responses, depending on the concentration range, exposure duration, plant species, class of Zn compounds, and treatment with unary or binary solutions (Ince et al, 1999;Marcato-Romain et al, 2009;Patra et al, 2004;Steinkellner et al, 1998), but also on the number of somatic and metacentric chromosomes or on the length of the diploid complement (Ma et al, 1995). Some reports state that high Zn concentrations are not strongly genotoxic (Codina et al, 2000;Gómez-Arroyo et al 2001;Marcato-Romain et al, 2009).…”

Remarkable Synergistic Effects in Antifouling Chemicals against Vibrio fischeri in a Bioluminescent Assay

“…In comparison with the respective single chemicals, the same concentrations of their combinations showed much higher inhibitory activities, which suggests that toxicity was enhanced because of the synergistic effect of their combination. 18,19) …”

A toxicidade em ambientes aquáticos: discussão e métodos de avaliação

“…10,71,72 O efeito é aditivo quando a toxicidade da mistura é igual à soma das toxicidades individuais de seus componentes. 71 Quando a toxicidade de uma mistura é maior que a soma das toxicidades dos seus constituintes há um efeito sinérgico e quando a toxicidade da mistura é menor que a soma das toxicidades de seus componentes, há um efeito antagônico.…”