In this blog post, we’ll explore the necessity, ethical issues, and scientific validity of animal experiments used in the development of pharmaceuticals and various products, as well as potential alternatives to animal testing.
Are Animal Tests Really Necessary?
With advances in medical technology today, vaccines have been developed to prevent various infectious diseases such as polio, rubella, and measles, and the incidence and mortality rates of some diseases have decreased significantly. However, not all vaccines completely prevent disease; while polio has been greatly reduced through vaccination, it still occurs in some regions today. While humanity has successfully eradicated some diseases through vaccination—such as smallpox—others, including tuberculosis, measles, and rubella, still require global management. A closer look at the development process for new drugs and vaccines reveals that it involves several stages, including drug discovery and synthesis, toxicity testing, preclinical trials, clinical trials, and drug approval. Throughout this process, animal testing has long played a crucial role. Animal testing is a process used to verify the efficacy and safety of new products or treatments, and it has been utilized not only for pharmaceuticals but also for evaluating the safety of pesticides, cosmetics, and food products. Generally, various species are used in animal testing depending on the research objectives, ranging from laboratory animals such as rodents to various mammals and other animals. According to data from 2012, it was estimated that approximately 500 million animals were used in experiments worldwide each year. It is more appropriate to view this figure as an estimate presented at that time rather than an accurate representation of the current global scale of use. From the perspective of companies and research institutions developing products, preclinical trials and animal testing have played a crucial role in ensuring that humans can safely use products and treatments. However, are these animal experiments truly a justifiable method, and are they procedures that must be carried out? I believe they are not.
Do animals have rights?
First, we can argue from the perspective of animal rights. Generally, animal rights can be explained as a concept that extends the human-centered notion of rights to animals, based on the view that animals, too, have the right to avoid suffering and lead their own lives. In fact, compared to human rights—which have been debated for centuries—the period during which animal rights have been seriously discussed is relatively short. Furthermore, scholars hold differing positions regarding the scope of animal rights, and opinions are even divided on whether animals should be granted rights at all.
The process of animal testing can be broadly categorized into “medical research,” “product testing,” and “exploratory, psychological, and military research.” In the “medical research sector,” researchers administer drugs to animals to evaluate side effects and safety during the development of pharmaceuticals, then observe the animals’ reactions. The “product testing sector” involves experiments related to various products—such as cosmetics and food additives—that people may ingest, apply to their skin, or inhale, even though these are not pharmaceuticals. In the past, experiments were conducted by directly instilling substances into rabbits’ eyes to determine whether cosmetics were safe if they came into contact with the eyes, or by forcing animals to inhale toxic gases.
In fact, most people are largely unaware of animal rights. Without any basis, humans naturally place themselves at the very top of the ecological pyramid as if it had always been that way, and exploit non-human animals according to their own needs and purposes. Even a glance at circuses and safaris—where animals are exploited for human entertainment—demonstrates that humans do not fully recognize animal rights.
Let’s reiterate the point mentioned earlier: humans infringe upon the safety and welfare of other animals in order to ensure their own safety. Humans administer drugs to animals, drip cosmetics into their eyes, and force them to inhale toxic gases. Why is it that, even though these actions are supposedly for human safety, only innocent animals are sacrificed? Why can’t experiments be conducted directly on humans? If it is because such actions would violate human rights, or because experimenting on humans is too inhumane, is it then justifiable to perform the exact same acts on other living beings that are not human? If we treat animals harshly simply because they cannot speak, can we do the same to newborn babies who also cannot speak? If an act cannot be performed on humans, shouldn’t it also be prohibited when performed on other living beings? Animals, too, have their own right to live, and there is no justification anywhere for humans to infringe upon that right simply because they are human.
Are meat-eating and animal testing the same issue?
If animal testing is an act that infringes on animal rights, one might counter that eating meat—such as pork or chicken—is also an act that infringes on animal rights. While I do not take a positive stance on meat-eating, I believe that meat-eating and animal testing are separate issues. While humans eating animals is related to issues of human survival and diet, I believe that using animals as test subjects for the benefit of humans is a separate issue that infringes upon animal rights. Humans are naturally omnivorous animals. The consumption of meat is a behavior that has long been associated with human diet and survival, and it is also connected to the natural order of things. Therefore, unlike animal experimentation, which is conducted for the proliferation of the species, I believe meat consumption should be distinguished from it because it is an act necessary for the very existence of the species.
Today, significant efforts are being made to protect the rights of these animals. In particular, academia and research institutions address animal welfare and the ethical issues of experimentation through the 3R principles. The 3R principles stand for Replacement, Reduction, and Refinement. In other words, experiments using live animals should be “replaced” with alternative methods whenever possible; the number of animals required to obtain the same level of scientific information should be “reduced”; and the pain or stress experienced by animals during the experimental process should be “refined” to the greatest extent possible. The 3R principles remain an important guiding framework in animal research today, and the U.S. National Institutes of Health (NIH) also requires the use of non-animal models when scientifically appropriate, the reduction of the number of animals used, and the minimization of pain and stress. This demonstrates that people are aware of the issues surrounding animal experimentation and are making efforts to reduce it. I believe this movement is a positive step toward reducing animal sacrifice.
However, it is difficult to view this as an action that fully protects animal rights. The aim of preventing excessive animal experimentation through the 3Rs principle ultimately presupposes that animal experimentation itself is permitted to a certain extent. The three principles—replacement, reduction, and refinement—are fundamental attitudes that researchers handling laboratory animals must adopt. However, establishing these as principles can only be interpreted as an effort to minimize animal sacrifice and suffering as much as possible, rather than a commitment to fully guaranteeing animal rights. Of course, these principles play a crucial role in improving animal welfare and reducing unnecessary experiments; yet, as long as animal testing exists, the conflict between animal rights and human research objectives will never completely disappear.
Just how effective are animal experiments?
In fact, the points discussed so far were somewhat fundamental and might have been viewed as lacking practicality. Let’s now look at animal experiments from a more practical perspective. To what extent are the animal experiments currently being conducted effective? Generally speaking, the effectiveness of animal experiments may be more limited than people tend to think.
This is because humans and non-human animals are distinctly different species, and the processes by which diseases develop, their symptoms, responses to drugs, and treatment methods can all differ. For example, while humans with high cholesterol levels are at high risk for coronary artery disease, certain animals may exhibit different diseases or physiological responses than humans. Furthermore, the physiological changes observed in neutered cats and women who have undergone hysterectomies are not identical. This indicates that biological differences exist between humans and other animals, meaning there are limitations to directly applying results observed in animals to humans.
The claim that diseases common to both humans and animals account for a mere 1.16% of human diseases has been repeatedly cited in materials explaining the limitations of animal testing. However, this figure is based on a simple calculation of the degree to which diseases are shared between animals and humans, and it has limitations when accepted as a general standard for evaluating the validity of animal models in modern biomedical science. Therefore, it is inappropriate to conclude, based solely on this 1.16% figure, that animal testing is effective only for 1.16% of diseases. That said, it is clear that substances or treatments confirmed to be effective and safe in animal testing do not guarantee the same results in humans, and that failures occur during the clinical trial phase due to biological differences between animal models and humans. Recent studies have also pointed out that a significant number of treatments that showed promising results in animal testing fail to reproduce the same effects in clinical trials involving humans.
There are cases where a substance causes no side effects in animals but results in severe side effects in humans, and conversely, cases where a substance causes problems in animals but not in humans. “Thalidomide” serves as an example. Launched in Germany in 1957, this drug was marketed as effective in alleviating morning sickness in pregnant women. At the time, animal studies had not sufficiently revealed thalidomide’s potential to cause severe birth defects, and it was considered a relatively safe drug for humans. However, many pregnant women who took thalidomide gave birth to infants with severe congenital malformations, such as limb defects, and this incident subsequently led to a significant strengthening of drug safety evaluation systems. The thalidomide incident is a prime example demonstrating that a drug cannot be deemed safe for humans simply because it passed animal testing. This is not the only instance. In Japan during the 1970s, people who took clioquinol—used as an antidiarrheal—suffered symptoms such as visual impairment and paralysis, resulting in numerous victims in what became known as the SMON incident. Rather than proving that animal testing is meaningless, these cases demonstrate that the results of animal testing alone cannot perfectly predict all risks that may arise in humans.
Are there no alternatives to animal testing?
Nevertheless, the reason people continue to conduct animal testing is that, in the pharmaceutical field, it has long been used as a means of nonclinical safety assessment to identify risks prior to clinical trials on humans. However, as I have repeatedly mentioned, it raises the question of why living animals, of all things, must be used as a safety measure for humans. Currently, many methods are being proposed to replace or supplement animal testing. For example, there are methods that involve culturing human cells to identify potential side effects at the cellular level, or computer modeling of biological reactions occurring in actual cells and tissues. In addition, various new approaches are being developed, such as organoids, organ-on-a-chip technologies, human cell-based models, and toxicity prediction using computer simulations and artificial intelligence. The U.S. Food and Drug Administration (FDA) is also pursuing a roadmap to reduce or replace animal testing in certain drug development processes starting in 2025, and in 2026, it released draft guidelines for utilizing new non-animal methods (NAMs) in drug development. Therefore, it is increasingly likely that animal testing will be reduced in the future through the use of cell, tissue, and organ models, as well as computer-based methods, that are more directly relevant to humans.
However, since current alternative methods cannot fully replicate all the complex biological and behavioral characteristics of living humans, it is difficult to say that we have reached the stage where all animal testing can be completely replaced immediately.
Are humans the masters of the ecosystem?
I believe the most ideal period for this Earth was before the development of civilization. Wasn’t the most ideal state when humans did not exploit animals to the point of violating ethical principles, when humans harmoniously occupied a place alongside other living beings within the ecological pyramid, and when humans lived as part of nature? However, as civilization began to develop, humans defined themselves as the most advanced life forms on Earth and have been acting as if they were the masters of the Earth. As mentioned earlier, many people say that humans occupy the top of the ecological pyramid. However, I do not believe humans belong at the top of the ecological pyramid. Rather, humans act as if they do not belong anywhere within the ecological pyramid at all; they are simply standing outside it and destroying it. One of the attitudes we must abandon as humans is “speciesism.” Just as white people mistreated Black people in the past, we must recognize that humans are mistreating and exploiting animals simply because they belong to the human species. Rather than viewing ourselves as a unique and special entity, we must see ourselves as just one species among the countless animals living on Earth and strive to live in harmony with them.
