Bioassays are typically conducted to measure the effects of a substance on a living organism. Bioassays may be qualitative or quantitative. Qualitative bioassays are used for assessing the physical effects of a substance that may not be quantified, such as abnormal development or deformity. An example of a qualitative bioassay includes Arnold Adolph Berthold's famous experiment on castrated chickens. This analysis found that by removing the testes of a chicken, it would not develop into a rooster because the endocrine signals necessary for this process weren't available. Quantitative bioassays involve estimation of the concentration or potency of a substance by measurement of the biological response that it produces. Quantitative bioassays are typically analyzed using the methods of biostatistics.

The use of bioassays include:

1. measurement of the pharmacological activity of new or chemically undefined substances
2. investigation of the function of endogenous mediators
3. determination of the side-effect profile, including the degree of drug toxicity
4. measurement of the concentration of known substances (alternatives to the use of whole animals have made this use obsolete)
5. Assessing the amount of pollutants being released by a particular source, such as wastewater or urban runoff.

Bioassays are essential in the development of new drugs, and monitoring pollutants in the environment. Environmental bioassays are generally a broad-range survey of toxicity, and a toxicity identification evaluation is conducted to determine what the relevant toxicants are. Although bioassays are beneficial in determining the biological activity within an organism, they can often be time-consuming, laborious, and organism-specific factors may result in data that isn't applicable to others in that species. For these reasons, other biological techniques are often employed, including radioimmunoassays.

See also

• Drug discovery
• Pharmacodynamics
• Pharmacokinetics
• Dilution assay

External links

• What is a bioassay (ToxicityLab.com)?
• Whole Effluent Toxicity Basics (PowerPoint file)