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The 3Rs: An Introduction

Replace - Reduce - Refine: the concept of the 3Rs began in 1954. Two young researchers produced a report, in which they examined the handling of experimental animals and the possibilities of a more humane science. However, it took another 30 years before anyone would deal with this topic seriously…

In-Vitro Methoden entwickeln sich rasant, der Einsatz von leistungsfähigen Computern beschleunigte den Trend.
In-Vitro Methoden entwickeln sich rasant, der Einsatz von leistungsfähigen Computern beschleunigte den Trend.

The "3Rs" (also known as the "3Rs principle" or the "3Rs concept") date back to 1954. At that time, the Universities Federation for Animal Welfare commissioned a young researcher named William Moy Stratten Russell to write a report on the progress of humane techniques in the laboratory. He was assisted by Rex Burch – later a microbiologist – who travelled the country for this report and interviewed hundreds of researchers. In a certain sense, two unusual personalities had sought and found each other: both had a special ability to look beyond the boundaries of a particular discipline. In this way, a revolutionary report emerged, «Principles of Humane Experimental Technique», which was supposed to lay the foundation for the 3Rs. The report was revolutionary in that (apart from a few exceptions) nobody at that time seriously considered the welfare of the experimental animals. On the contrary, the prevailing view was that consideration for the needs of the experimental animal was an unnecessary obstacle to research.


For the first time in this work, published in 1959, there was a discussion of the three principles that humane research should be based on:


  • Replace: living and feeling experimental animals should be replaced as far as possible by non-sentient matter.
  • Reduce: the desired aim of the experiment should be achieved with as few animals as possible.
  • Refine: the experimental animals used are treated in a way that alleviates pain, suffering or distress, and enhances animal welfare. This refers to the entire life of the animal: breeding, transport, husbandry, experiment, and possibly killing.

After the release, as is often the case with pioneering work, things stayed quiet around the 3Rs. Only with the advances in cell culture in the mid to late 1980s, the concept finally began to take off. With the possibility of keeping individual cells alive and functioning for a while with the help of antibiotics and nutrient media, and examining them in test tubes (in vitro), researchers were finally offered a method that could do without the living experimental animal. In addition, the time was ripe: a sensitized public began to question more and more vigorously the meaning and nonsense of animal experiments, animal welfare legislation became increasingly stringent, and researchers also started to see the in vivo experiment more critically.


Since then, the in vitro methods have been developing rapidly. The widespread introduction of powerful computers gave this trend another boost: with their help, it is now possible to simulate possible interactions among cells and, e.g., a drug (so-called in silico methods).


Today, the 3Rs are firmly anchored in national and international legislation. Nevertheless, there is still much to be done: the inertia of old systems should not be underestimated. The current developments are however encouraging. Young scientists have naturally accepted the demands of the 3Rs concept as part of their research, and an ever-growing network of scientists around the world is working on the further development and acceptance of alternative methods to animal experiments. A major task for the next few years will be to put the existing non-animal methods into practical use. This is also our goal.