This blog post examines the scientific validity and ethical issues surrounding animal testing conducted for drug validation, along with possible alternative methods and their limitations.
With industrialization, the development of new drugs and the medical industry have advanced dramatically, leading to the emergence of various methods for evaluating drug efficacy. Simultaneously, questions are being raised about the validity of ‘animal testing,’ currently the most widely used standard for drug evaluation. Animal testing refers to experiments conducted on all animals except humans. Approximately 200 million animals are sacrificed for testing worldwide each year. In South Korea alone, it is estimated that around 3 million animals are sacrificed annually. This is because many countries, including South Korea, rely on animal testing as a standard for drug evaluation. But is animal testing truly an effective method?
In reality, while the difference in human DNA base sequences is less than 1% even between individuals of different genders, races, or birth regions, the DNA difference between humans and monkeys, known to be similar to humans, reaches about 16%. Furthermore, diseases common to both humans and animals account for only about 1.16% of all diseases; most cancers, AIDS, dementia, etc., are diseases that appear only in humans. Dr. Klausner of the National Cancer Institute in the United States stated, “The history of treating cancer in humans is the same as the history of treating cancer in mice. We have been treating cancer in mice for decades, but frankly, it hasn’t worked for humans.” Given such significant differences in genetic sequences and the scarcity of shared diseases, it raises serious questions about whether experimental results from animals can truly be applied to humans.
The problems with animal testing extend beyond theory to real-world cases. Thalidomide, developed in Germany in 1953 to prevent morning sickness in pregnant women, was deemed safe after multiple animal trials and exported to over 50 countries, hailed as a “miracle drug.” However, its use resulted in 12,000 babies born with deformities within a single year. Side effects not detected in animal testing manifested in humans. While the pharmaceutical company claimed no harmful effects appeared in experiments on mice, rabbits, and pigs, it was ultimately revealed that thalidomide’s optical isomer difference caused severe teratogenic side effects only in humans.
Beyond the thalidomide case, many drugs exhibit differing effects between humans and animals. For example, penicillin, a commonly used treatment for bacterial diseases, is beneficial to humans but can be poisonous to guinea pigs. Furthermore, morphine, used as a sedative in humans, acts as a stimulant in cats. Because drug effects vary depending on the animal species, directly applying animal test results to humans is inappropriate.
Additionally, animal testing suffers from the problem of inefficient results relative to the costs incurred. As the author of Greed and Arrogance in Animal Testing stated, “Mice are animals that vomit out papers when given drugs,” animal testing is frequently used in academic research, yet its utility is questioned. While 200 million animals are used in animal testing annually, only 25 new drugs are registered with the U.S. Food and Drug Administration (FDA) each year. Repeating ineffective animal experiments to produce papers risks disseminating flawed research results, potentially leading to another Thalidomide-like disaster.
Another problem is that animal testing should be prohibited from an ethical standpoint. Animal testing is justified by applying different ethical standards to animals and humans. The ethical basis cited for animal testing is the presence or absence of ‘moral agency’. This refers to the capacity to voluntarily adhere to norms based on social concerns, public opinion, and customs. This raises two contradictions. First, while infants or brain-dead individuals are excluded from animal testing despite lacking cognitive ability or moral agency, they are not considered to possess these qualities. This demonstrates that the ethical criteria for animal testing fail to provide a valid basis for distinguishing humans from animals. Second, despite ongoing research demonstrating that animals like monkeys and dogs possess moral agency, these animals continue to be used as sacrificial subjects in experiments.
Furthermore, there are numerous cases where animal experiments proceed unnecessarily in violation of regulations. According to the Animal Experimentation Code, “Research using animals should only be conducted after considering whether the potential adverse effects on the welfare and well-being of the animals can be justified by the educational value or scientific importance of the research. Researchers must consider animal welfare and treat animals with respect when planning and conducting research.” However, experiments contrary to this code are actually being performed. For example, even after the harmful effects of smoking were clearly established by the early 21st century, experiments were still conducted where holes were drilled into the necks of dogs and monkeys to expose them to cigarette smoke. It is difficult to argue that this satisfied educational value or demonstrated respect for the animals. Animal testing requires reevaluation not only for its practicality but also from an ethical standpoint.
Currently, many excellent alternative methods to animal testing have been developed. In vitro studies and mathematical modeling are prime examples. In vitro studies involve culturing target organs in test tubes to observe whether drugs cause adverse effects. Since certain cancers unique to humans cannot be tested on animals, research is conducted by transferring cancer cells to cultured target organs in test tubes. Mathematical modeling predicts whether drugs will cause adverse effects in humans by applying mathematical formulas to computer simulations. Indeed, the side effects of thalidomide, which were not revealed through animal testing, could be identified through mathematical modeling. Insisting on animal testing despite these practical and ethical alternatives is irrational.
Interest in and development of pharmaceuticals will continue. While animal testing has clearly contributed to medical progress, it is also true that victims have resulted from incidents like thalidomide during this process. Preventing a second thalidomide disaster must be prioritized, given the uncertainty of when a new drug’s side effects might be discovered. Of course, halting animal testing immediately could temporarily set back medical progress. However, blindly pursuing animal testing, with its ethical and practical limitations, greatly increases the likelihood of second and third thalidomide incidents. Therefore, animal testing should be gradually reduced while expanding alternative research methods. Furthermore, when animal testing is unavoidable, experimenters must strictly adhere to guidelines and approach experiments with the utmost responsibility toward the animals. Society must also strictly manage animal testing regulations and rigorously control compliance.
