Electrophiles and acute toxicity to fish.

Effect concentrations in fish LC50 tests with directly acting electrophiles are lower than those of unreactive chemicals that act by narcosis. LC50 values of more hydrophobic reactive chemicals tend to approach those of unreactive chemicals. Quantitative studies to correlate fish LC50 data to physical-chemical properties indicate that LC50 values of reactive chemicals depend on hydrophobicity as well as chemical reactivity. In this paper, several examples will be given of chemical structures that are known as direct electrophiles. This classification might be useful to identify chemicals that are more effective at lower concentrations than unreactive compounds. Chemicals that require bioactivation are not included because almost no information is available on the influence of bioactivation on acute toxic effects in aquatic organisms.