Alternatives to animal testing: Are they more reliable?
More than 115 million animals worldwide are used in laboratory experiments every year. 95% of all drugs shown to be effective in animal tests fail in human trials.
Animal testing raises ethical and scientific concerns, as animals used in testing experience pain, suffering, and distress. The results of animal studies are shown to not only be inaccurate translations of human responses but, in many cases, have caused serious harm to humans.
Fortunately, increases in scientific innovation and growing support to find alternatives to animal testing means alternative methods are rising.
Why is animal testing unreliable?
It’s no surprise that animals are anatomically, metabolically, and genetically different from humans; many drugs deemed effective in animals fail in human clinical trials, highlighting the limitations of animal testing in predicting human response. Animal studies often use high doses of a substance to induce a response which doesn’t translate to humans.
Throughout history, we have seen animal experiments deemed safe that have dire consequences for humans. In the 1950s, a drug to treat morning sickness, Thalidomide, did not cause congenital disabilities when given to pregnant rats and mice, but in humans, it caused epidemics of congenital disabilities, including severe limb malformations.
In 1993, a potential treatment for hepatitis B was approved for human testing after a six-month trial on dogs; however, five of the fifteen participants died, and a further two people required liver transplants.
Another example from 2006 left human volunteers in critical conditions, including chronic organ failure, after trailing TGN1412, a treatment for autoimmune diseases and cancer. Scientists relied on the treatment being tolerated by monkeys in the pre-clinical trials. For more cases, follow PETA’s Without Consent timeline.
Animal experimentation is unreliable, which begs the question, why does it continue, and what are the alternatives to animal testing?
Why does animal testing exist if it’s unreliable?
Despite the growing evidence that non-human testing is unethical and unreliable, it continues due to some regulatory requirements; however, a significant legislative breakthrough happened in the US with President Biden signing the FDA Modernization Act 2.0 in December 2022, which “ends a 1938 federal mandate that experimental drugs must be tested on animals before they are used in human clinical trials”. Although it doesn’t ban animal testing, it allows drug companies to use alternatives, whereas before, they had to test on animals.
In 2009 the EU ban on animal testing of cosmetic ingredients came into force; however, competing legislation such as the EU’s chemical regulations means that some chemicals, which are for cosmetic use are tested on animals. The tradition of animal testing lingers as some scientists and researchers still believe that animal testing is necessary for advancing medical research and developing new treatments, despite the limitations and ethical concerns. Luckily, scientific innovation means alternatives to animal testing are proving successful and garnering support.
So, what are some alternatives to animal testing?
In vitro methods
In vitro methods use cell cultures, organoids, or tissue chips to test the safety and efficacy of products without using live animals. Scientists coax cells to grow into 3D structures, such as miniature human organs, to test therapies.
A scientific review of lung-on-a-chip devices (made with molecules naturally found in the lung: collagen and elastin) for evaluating the impact of air pollution on human lungs suggests that in vitro testing “will bring more reliable data to support animal replacement in the future”. Animal testing is biased and, therefore, misrepresents results “owing to the differences in the structures and functions of the respiratory tracts of different species”.
Computer simulations and mathematical models (which replicate the ‘model’ of parts of the human body) can be used to predict the effects of chemicals and drugs on human physiology.
One example includes novel computational models whereby computer-based simulations assess the eye irritation and corrosion potential of chemicals. These models use mathematical algorithms and data from various sources, including chemical structure, to predict a substance's potential to cause eye irritation or corrosion.
Volunteers can participate in microdosing, which involves administering minuscule amounts of new drugs to measure their effects on the human body which “can only improve predictions of drug toxicity and efficacy, whilst also reducing the resources spent and the number of animal tests carried out” as well as allowing participants to provide first-hand accounts of their experiences, making it easier to understand and interpret the results.
Human volunteer studies
Clinical trials involving human volunteers can provide important information about the safety and efficacy of drugs and treatments.
Some trials use highly sophisticated scanning machines, and recording techniques have been developed to study human volunteers safely. Brain imaging machines, which can peer inside the brain, can be used to track the progression and treatment of brain diseases. By comparing results with healthy volunteers, these machines can aid researchers in comprehending the underlying causes of these diseases.
Human tissue and organ banks
These banks store human tissue and organs that can be used for research and testing, reducing the need for animal testing. Healthy and diseased tissues from human volunteers provide a more realistic way of studying human biology and disease than animal testing. Tissue can be donated from biopsies, cosmetic surgery, transplants, and post-mortem.
Adverse outcome pathways
The Adverse Outcome Pathway (AOP) concept offers a framework to “make faster progress to research, develop and evaluate human-relevant methods and reliably interpret their results, for better safety prediction and disease research”. This approach uses a weight-of-evidence approach to assess the potential harm of a substance based on existing data and knowledge of biology and toxicology.
Hope for the future?
The monumental FDA amendment evidences that non-animal testing is proving successful as some legislative bodies are easing the requirements to test on animals. Technological advances and the emphasis on ethical practices mean there is some hope. However, animal testing still occurs worldwide, so as consumers, it’s essential to support, where possible, companies and products that do not test on animals.