Animal toxicity tests are crude, subjectively assessed and the results can vary depending upon the species, age, sex and condition of individual animals. One international study that examined the results of rat and mouse LD50 (Lethal Dose 50%) tests for 50 chemicals found that these tests were able to predict toxicity in humans with only 65% accuracy.
(1) (see page 17) Dr Robert Sharpe, research chemist, states, “The LD50 for digitoxin in rats is 670 times that in cats, whilst for the antifungal substance antimycin, the LD50 in chickens is 30-80 times greater than in pigeons and mallards. The LD50 of thiourea in the wild Norway rat is 450 times greater than in the Hopkin’s strain of rat.” (2)
Manufacturers are simply asked to conduct whatever tests are appropriate, in their opinion, to establish that their cosmetics or household products are safe. Even the environmental conditions in a laboratory can affect results.
The LD50 results for the same chemical can vary widely between different laboratories. It is hardly surprising then to learn that results from animal tests are often difficult to apply to humans. Many substances tested safely on animals have proven to be dangerous to humans and vice versa.
The Real Reasons
Animal tests were crudely developed as long ago as the 1920s and became commonplace in the 1940s. Scientists are familiar and comfortable with the animal-based techniques they have been using for years. It is always difficult to change the status quo. Companies continue to test on animals for legal protection.
Animal testing is designed to protect a manufacturer against legal claims by consumers. The irony is that the defence “we have safety-tested our products on animals” only becomes relevant when that testing fails to detect a potentially dangerous substance and a consumer is injured.
There is no actual legal requirement for animal testing. Manufacturers are simply asked to conduct whatever tests are appropriate, in their opinion, to establish that their cosmetics or household products are safe. The use of animals in laboratories is supported by a very large and powerful industry.
It includes contract testing laboratories, the suppliers of cages, equipment, animals, and infrastructure. Alternatives to animal testing Today, many cosmetic and household product companies have turned their backs on animal testing and begun taking advantage of the many sophisticated non-animal test methods available, which range from cell and tissue cultures to computerised “structure-activity relationship” models. Human cell culture tests have been found to predict toxicity in humans with much greater accuracy than animal tests.
(1) R. Roggeband et al., “Eye Irritation Responses in Rabbit and Man After Single Applications of Equal Volumes of Undiluted Model Liquid Detergent Products,” Food and Chemical Toxicology, 38 (2000): 727-734. (2) Dr Robert Sharpe, “The Cruel Deception”.
Chemical toxicity (poisoning) testing on animals involves subjecting animals to different levels of potentially toxic substances via different routes of exposure in order to assess how and in which way they are affected.Many products are tested to see if they will cause damage to the skin or eyes.
This approach to chemical testing, which uses animals and is mainly observational, subjective and descriptive, is extremely crude. Animal tests tell us little about why a substance is toxic, as the results tend to demonstrate effects rather than causes of toxicity. The test results are difficult to extrapolate from laboratory conditions to real life exposure of humans.
Their credibility is based on established use rather than proven predictive value. Most standard animal tests were developed decades ago and have either never been validated, or have actually failed retrospective validation (for example, the Draize eye test, the Lethal Dose 50% test and carcinogenicity).
Use of this drug for treating heart failure led to 20% of patients developing thrombocytopenia (lack of blood cells needed for clotting), despite a comprehensive program of animal studies in mice, rats, hamsters, guinea pigs, dogs and rhesus monkeys. Some of these [human] patients died.
Birth control pills
This anti-diarrhoeal passed tests in rats, cats, dogs and rabbits. It was pulled off the shelves all over the world in 1982 after it was found to cause blindness and paralysis in humans.
This synthetic oestrogen was designed to prevent miscarriage, but it did just the opposite by increasing the rate of spontaneous abortions, premature births and neo-natal deaths. No human trials were done; all the safety data was collected from animals.
This heart drug was withdrawn after causing serious side effects in an estimated 7,000 victims, 23 of whom died. It had been tested for six years in mice, rats, dogs and monkeys and when introduced on the market was “particularly notable for the thoroughness with which its toxicity was studied in animals, to the satisfaction of the authorities”.(1) Even long after the drug was withdrawn, scientists failed to reproduce these results in animals.
This antibiotic progressed through animal testing, only to cause seizures and psychosis when used by humans.
A medication used to treat asthma, it proved devastatingIy toxic to humans in the amounts recommended based on animal studies. In Great Britain alone, 3,500 asthmatics died from using the medication.
This treatment for migraine led to severe scarring of the heart, kidneys and blood vessels in the abdomen, although scientists had been unable to reproduce these effects in animals.
This treatment for rheumatism and arthritis killed 61 people and caused 3,500 adverse reactions. Withdrawn in 1982, the drug had been tested on monkeys and other animals for nine years with no adverse side effects.
This drug, found in many common cold and flu remedies, was banned by the FDA in the US after it was linked to causing between 200 and 500 strokes in young women a year.
This arthritis drug was withdrawn from the market when patients suffered kidney toxicity. Prior to its release, researchers said this about the animal tests: “…excellent safety profile. No cardiac, renal [kidney] or central nervous system [side effects] in any species.”
From Sacred Cows and Golden Geese – the Human Cost of Experiments on Animals
Arguably the most successful drug ever, causes birth defects in mice and rats and results in such extensive blood abnormalities in cats that they can only take 20% of the human dosage every third day. Another painkiller, ibuprofen, causes kidney failure in dogs, even at low doses. Other prescription drugs were initially unavailable to people because animal studies predicted side effects not found in humans. They include:
Are used in a variety of conditions, ranging from brain tumors to skin diseases. They have been shown to cause cancer in some rodents, despite their being used safely by humans for years.
This contraceptive was barred from release in the US in 1973 because it caused cancer in dogs and baboons
This anti-rejection drug was almost shelved before it proceeded to clinical trials. After experimenting on dogs, researchers said animal toxicity was too severe to proceed to the clinical trial stage
Mice, rats and hamsters suffer liver damage from this diuretic, but humans do not. It is widely prescribed for the treatment of high blood pressure and heart disease
The release of penicillin was delayed when its discoverer, Alexander Fleming, put it to one side because it did not work in rabbits. This is because rabbits excrete penicillin in their urine. Only when Fleming had a sick human patient and nothing else to try, did he administer penicillin – with excellent results.
The release of this gastrointestinal medication was delayed for 12 years because of an effect in animals which did not occur in humans.
This popular antibiotic caused birth defects such as limb malformations in the offspring of rats.