In this blog post, we will examine the ethical issues and scientific limitations of animal testing and introduce various alternative testing methods that can advance science without causing pain to animals.
Animal testing refers to experiments or scientific procedures conducted on laboratory animals for scientific purposes such as education, testing, research, and the production of biological preparations. It is estimated that approximately 500 million vertebrates are used as laboratory animals worldwide each year. This figure does not include invertebrates. Most laboratory animals are euthanized after the experiments are completed. Laboratory animals are usually bred in large numbers, but some are captured in the wild. Experiments are conducted extensively not only at universities, hospitals, and farms, but also at pharmaceutical companies, cosmetics companies, food companies, and many other places. Animal experiments are used not only for pure research to observe genetic characteristics, growth processes, and behavioral patterns, but also for xenotransplantation, drug response testing, and toxicological testing. These animal experiments are controversial due to ethical issues.
There have been ongoing calls to reduce unnecessary animal experiments and ensure animal rights and welfare, but various forms of animal experiments are still being conducted in many fields. Supporters of animal testing argue that medical advances in the 20th century were made possible by animal testing. They also argue that animal testing is necessary because even the most sophisticated computers cannot accurately understand the interactions between molecules, cells, tissues, organs, organisms, and the environment.
However, there are also arguments that animal testing is not useful enough to justify the suffering and death of animals. Bioethicist Peter Singer criticizes anthropocentrism, which values only human happiness, as a form of speciesism, ultimately no different from racism or sexism. I agree with Singer’s view. We are sacrificing laboratory animals for the benefit of humans alone. However, even leaving ethics aside, there are many scientific reasons to stop animal testing. The most important of these is that animal testing is no more effective than other types of testing, and in some cases is even less effective. Not conducting animal testing may be more beneficial in terms of scientific results. Some people can drink a lot of alcohol without getting drunk, while others get drunk quickly. Since people react differently to drugs, animal experiments must use different species of animals to overcome the differences in physiological functions between humans and animals. The methods and dosages used in animal experiments differ from those used in actual human situations, and only 1.16% of the 30,000 diseases that humans have are shared by animals, so the results of animal experiments are not very helpful in understanding humans. In fact, cases of drugs that have completely different effects on humans and animals, such as clioquinol and penicillin, have been used as strong grounds for denying the validity of animal experiments. For example, the antidiarrheal drug clioquine passed tests on rats, cats, and dogs, but in 1976, 10,000 people in Japan who took this drug suffered from vision loss, disabilities, and paralysis, and hundreds died. However, because it had passed animal testing, it was not initially suspected, and it was not until 1982 that it was banned worldwide. Conversely, penicillin, which has no side effects in humans, causes limb deformities in mouse fetuses. Fleming is said to have remarked, “It’s a good thing we didn’t do animal testing.”
Currently, the academic stance on animal testing is represented by the 3Rs principle. The 3Rs principle refers to efforts to replace experiments with methods that avoid the use of live animals, reduce the number of animals used to obtain the same amount of data, and refine the experiments to alleviate the pain felt by animals through anesthesia and other means. Based on these basic principles, guidelines on animal experimentation have been established by relevant academic societies, and it is required that the breeding and management conditions of animals used in research and the experimental methods be described in detail in the paper. In other words, research results obtained through animal experimentation must be evaluated as justified not only on a scientific level but also on an ethical level in order to be recognized by the academic community.
Animal experimentation raises ethical issues because it involves experimenting on living animals, and the results may not be accurate because humans and animals react differently to drugs. However, since it is not possible to conduct clinical trials directly on humans, there is no alternative to animal experimentation at this point. That is why I support the 3Rs principle. However, no matter how useful animal experiments may be, future research should move toward finding alternatives to animal experiments and eliminating animal sacrifice. With the appropriate use of cadaver research, experiments using human cells and tissues, and computer simulations, it is possible to obtain more information than can be obtained through animal experiments without conducting animal experiments. Recently, various alternative methods have been developed, such as using human cells or artificial skin instead of live animals, and utilizing computer modeling that mimics human responses.
One method that replaces animal testing is the “Organ-on-a-chip” developed by the Harvard Bioscience Institute in the United States. This is a thumb-sized device consisting of a thin membrane made of human cells and a microchip that pumps a blood-like liquid. So far, chips that mimic the contraction of intestinal muscles and chips that exchange oxygen and carbon dioxide like the lungs, equipped with air sacs and capillary cells, have been developed. Lung-on-a-chip mimics diseases and disease conditions. It can even cause complications caused by chemotherapy side effects, such as pulmonary edema. The research team is currently conducting additional research to create chips for bone marrow, the heart, and the brain.
Computer modeling can also be a good substitute for laboratory animals. This is because system biologists are creating 3D digital maps of the human body that can accurately simulate all human tissues and organs at the molecular level. For example, the Center for Systems Biology at the University of Iceland recently completed modeling of all chemical interactions that occur in human metabolism and has begun modeling blood.
In addition, there are increasing cases of direct experimentation on the human body, such as genetic testing. This is in consideration of the fact that the same drug can have different effects depending on the individual, as there are significant differences in DNA between individuals, and is linked to the development of personalized medicine.
Of course, regardless of these changes, animal testing will continue to be recognized as scientifically necessary for quite some time. This is because there are things, such as the eye and the brain, that cannot yet be perfectly reproduced by any means. However, we must conduct experiments in accordance with the 3Rs principle and ultimately research alternative methods that do not require the sacrifice of animals.
