Bioassay

A bioassay is an analytical method to determine concentration or potency of a substance by its effect on living cells or tissues. Bioassays are used to estimate the potency of agents by observing their effects on living animals (in vivo) or tissues (in vitro). A bioassay is an analytical method to determine concentration or potency of a substance by its effect on living cells or tissues. Bioassays are used to estimate the potency of agents by observing their effects on living animals (in vivo) or tissues (in vitro). A bioassay experiment can either be qualitative or quantitative, direct or indirect. If the measured response is binary, the assay is qualititative, if not, it is quantitative. Bioassay is used to detect biological hazards or give a quality assessment of a mixture. Bioassay is often used to monitor water quality and also sewage discharge and its impact on surrounding . It is also used to assess the environmental impact and safety of new technologies and facilities. Bioassay is a biochemical test to estimate the relative potency of a sample compound to a standard compound. Typical bioassay involves a stimulus (ex. drugs) applied to a subject (ex. animals, tissues, plants) and a response (ex. death) of the subject is triggered and measured. The intensity of stimulus is varied by doses and depending on this intensity of stimulus, a change/response will be followed by a subject.. The first uses of bioassay dates back to as early as the late 19th century, when the foundation of bioassays was laid down by a German physician, Paul Ehrlich. He introduced the concept of standardization by the reactions of living matter. His bioassay on diphtheria antitoxin was the first bioassay to receive recognition. His use of bioassay was able to discover that administration of gradually increasing dose of diphteria in animals stimulated production of antiserum. Many of the early bioassays consisted of using animals to test carcinogenicity of chemicals. One well known example is a 'canary in the coal mine' experiment. To test for methane, miners would take methane-sensitive canaries to coal mines to ensure safe air. In 1915, Yamaigiwa Katsusaburo and Koichi Ichikawa tested the carcinogenicity of coal tar using inner surface of rabbit's ears. Through 1940s and 1960s, animal bioassay was primarily used to test for toxicity and safety of drugs, food additives and pesticides. In late 1960s and 1970s, reliance on bioassay increased as the public concern for occupational and environmental hazards increased. While before this health risks of certain chemicals such as pesticide was tested in animal bioassay, it was still rare and testing was not seen often. - The stimulus/standard sufficiently produces measurable and specific response. The response must be clear, easily recognized, and directly measured.