Bioassay

A scientific experiment that assesses the effects of certain substances (toxins) on animals.

In a bioassay (biological assay), different concentrations of a test substance (e.g. Bt toxin) are administered with food. The animals chosen for testing are usually ones that are known to be, or suspected to be, sensitive to the substance. Bioassays usually measure the impact on animal growth and weight gain and frequently establish the dose at which 50% of the trial animals die (LC 50; LC = lethal concentration). The scientists check after a certain amount of time (one or more days, depending on the experimental design) how many animals have survived.

Bioassays are primarily used to test new drugs and to monitor substances that might pollute the environment.