Abstract :
Unifying concepts are needed in ecotoxicology to deal with the various aspects of the behavior of substances, such as their mobility in the physical environment, bioaccumulation, toxicity, and specificity. The concept of transformity (the relative amount of energy required to generate a component or a flow in a transformation process) may provide a synthetic approach. Transformity correlates positively with the bioaccumulation tendency and toxicity. Since increasing amounts of energy are required in biological or industrial processes that generate increasingly unusual, complex, and specific substances, transformity and specificity may correlate positively as well. This latter hypothesis was tested for a set of 45 compounds, including simple and chlorinated alkanes, alkenes, alcohols, benzenes, and phenols. Published data on their Gibbs energy of formation (an estimate of transformity) and their acute toxicity to 21 species of aquatic organisms (measured as the EC50or LC50, the duration of the test depending on the life span of the species) were used. To quantify specificity, the coefficient of variation of the toxicity data for the various species, which expresses the relative variability of the data around the mean, was calculated. There was a significant positive correlation between these two quantities. Thus, transformity may provide a conceptual framework for predicting the specificity of substances. The functional relationship between transformity and specificity could not, however, be established with certainty.
