Toxicity testing

“Environmental risk assessment of chemicals is essential but often relies on ethically controversial and expensive methods,” i.e., testing the effects of chemicals on the growth of live, juvenile fish. So begins a paper recently published in the journal Science Advances.

“Every year, more than a million fish are used for experimental and other scientific purposes in the European Union,” the authors of the paper write; they also note that three to six million fish are “used for whole effluent testing” every year in the United States.

Researchers have developed another method for testing the effects of chemicals on living tissue, one that uses cells for test subjects instead of whole fish. If this method is equally as effective as the old technique, then both money and the lives of a multitude of fish could be saved.

In order to evaluate the new, cells-only method, scientists cultured cells from fish gills, exposed the cells to two different pesticides, then monitored their survival and proliferation. Based on how the cells grew, they estimated how much an entire fish would grow if it were exposed to the relative levels of the two chemicals they tested.

The estimates of whole-fish growth were a good match for data collected in a previous experiment, during which fish themselves were exposed to the pesticides. This, the researchers write, “comprises a very promising step toward alternatives to whole-organism toxicity testing, especially taking into consideration the simplicity, rapidity, and low costs of this method.”

“We hope,” they write, “that our very encouraging results inspire further work on alternatives to animal testing,” a prospect that could benefit both fish and humans.

Currently, many toxicology studies rely on live fish as test subjects. Such studies often assess fish at different life stages, from embryos (such as the zebrafish embryo pictured here) to adults. 

(Image by ZEISS Microscopy via Flickr/Creative Commons license)