The Three Rs The Three Rs. Two British scientists, William M.S. Russell and Rex Burch, first described the three Rs in The Principles of Humane Experimental Technique, a 1959 book. The authors stated that good science and animal welfare go hand in hand. As the use of animals in research evolves, the three Rs still stand as an overriding principle for scientists.
Replacement refers to methods that substitute for the use of whole animals.
For example, laboratories no longer use rabbits for pregnancy tests. Today, however, a simple test available in drug-stores achieves the same result. Reduction refers to methods that result in fewer animals being used to acquire necessary information. For example, scientists are developing a number of in vitro tests to assess eye and skin irritation. In an in vitro test, scientists apply a substance to human or animal cells or tissues in a laboratory container rather than in a living animal.