General Principles of Toxicity and Its Application

Abstract

A particular test should be widely accepted by scientific community and be able to predict the effects of wide range of chemicals on different organisms. Toxicity testing methods have been designed from time to time using different procedures. Acute toxicity describes the adverse effects of a substance that result either from a single exposure or from multiple exposures in a short space of time. In order to be described as acute toxicity, the adverse effects should occur within 14 days of the administration of the substance. Acute toxicity is distinguished from chronic toxicity, which describes the adverse health effects from repeated exposures, often at lower levels, to a substance over a longer time period (months or years). The objective of acute toxicity test is to determine the concentration of a test material or the level of an agent that produces a deleterious effect on a group of test organisms during a short-term exposure under controlled conditions. LC50 is statistical estimate of dose necessary to kill 50% of a large population of test species under stated conditions. Experimentally this is achieved by administering a chemical at graded doses to a group of organisms and then observing the resultant mortalities in a set time period, 96h and so on. Among animals, rats, mice, rabbits, guinea pigs and hamsters are the test species. Subacute toxicity study aims to find out toxic effect of drug on repeated exposure and also provide the valuable information, that is, delayed effect which may result due to the cumulative effect of the chemicals on the tissues or other biochemical mechanisms. General Lab Practice (GLP) is concerned with the organisational process and the conditions under which laboratory studies are planned, performed, monitored, recorded and reported. GLP is concerned with the organisational process and the conditions under which laboratory studies are planned, performed, monitored, recorded and reported. The GLP requirements deal with all related aspects of testing, namely, personnel, facilities, equipment, laboratory operations, test chemicals, protocols, reports and disqualification of testing facilities.