3R Principle and Alternative Toxicity Testing Methods

Toxicity tests are essential for evaluating the safety or hazards of several substances. Many of the current toxicity testing methods include the use of animals, especially rodents. However, in the last three decades, there has been an inclination towards using less animals and performing alternative methods that reduce, refine and replace animal use (3R principle). The viewpoint of “reduction” is to decrease the number of animals required for a test method, while remaining consistent with scientific practices that are necessary to aquire valid results. The standpoint of “refinement” is using procedures that bring less pain or distress in animals. The aspect of “replacement” is to use non-animal systems instead of animals, or to use a phylogenetically lower species of live animals. Among all approaches, the use of alternative techniques replacing animals has a potential for the future research. The alternative test methods include in vitro models like cell cultures, and tissue/organ assays and in silico testing. Cell cultures have several advantages and scientist expect that in vitro testing will succeed against in vivo testing in the forthcoming years. This review will focus on the 3R principle and alternative test methods.