The Behavioral and physiological impacts of the hormesis of chemical contaminants on embryonic zebrafish

Abstract

Pharmaceutical chemicals are being produced, consumed, and excreted in human civilization at an increasing rate. These chemicals have the capacity to accumulate, especially in environments such as freshwater systems, but there have not been any major responses to this threat yet as the present concentrations of the chemicals is not viewed as dangerous. Previous research has shown that the developing concentrations of chemicals is an issue, supporting that these chemicals, though not present in large doses, have impacts on exposed organisms. However, prior research has not been conducted to examine the specific effects of chemicals at hormetic concentrations on freshwater organisms. “Hormetic concentration” defines the concentrations of chemicals at specific levels where the response to a low dose of chemical differs from the response to the high dose, and these were the ranges of concentration that were tested in this experiment.  Zebrafish were acquired at zero days post fertilization, transferred to the medium containing the appropriate concentration of chemicals for the group that they would be a part of, and used as a model for aquatic organisms to show the resulting chemical, neural, and physical response to the chemical concentrations. The zebrafish were euthanized via bleaching and freezing prior to seven days post fertilization. The results of this experiment show that there is an ecological risk associated with the environmental accumulation of pharmaceutical chemical contaminants that is inherent to their use in human civilization, a result which makes it clear that this issue needs to be addressed.