Chemical softness and acute metal toxicity in mice and Drosophila

Abstract

Correlations reported by Jones and Vaughn (1978) between chemical softness parameters and LD50s for metal compounds in rodents have been confirmed and extended. In the present study 14-day LD50s for mice were determined under uniform experimental conditions for 24 metal salts injected ip. For certain ions the correlation between the LD50 and the Pearson and Mawby (1967) softness parameter, σ p is better than that obtained by Jones and Vaughn (1978) using data from diverse sources. Notably, however, we found no orrelation for the alkaline-earth metals either with σ p or with other softness parameters. In parallel experiments with the same metal compounds, we also found correlations between σ p and 4-day LC50s for Drosophila exposed to the salts in their food. For both the mouse and Drosophila, soft ions were generally found to be more toxic than hard ions such that their rankings are significantly correlated. Several differences in relative toxicities of the metal ions were found to occur between mice and Drosophila, and some interpretations of these findings are give. Correlations between toxicity and physicochemical parameters of toxic materials can offer insights into biochemical mechanisms of toxicity and may be useful in predicting toxicity.