Argument Layout: Against Animal Testing

SHOULD WE REPLACE ANIMAL TESTING IN THE MEDICAL FIELD WITH ALTERNATIVE METHODS?

Affirmative Arguments:

1. Their poor reliability (more reliable alternatives) 2. Unnecessary cruelty to animals (causing controversy)

Reliability/Alternatives

Reliability

Cigarettes were considered safe because smoking-related cancer is almost impossible to reproduce in non-human animals. The primary purpose of medical research is to promote human health, and the most direct research methods focus on the study of human populations, individuals, and tissues. Animal research has been used merely as an alternative method when study of humans is deemed impractical or unethical. In addition to the ethical issues, the profound differences in anatomy, physiology, and biochemistry between humans and animals make animals poor models for humans. Results from research on animals cannot be accurately extrapolated to humans and are poor predictors for how humans will respond to drugs, treatments, or diseases.

This process has been regularly criticized by doctors and scientists, who insist that animal testing is unscientific, erroneous, and a danger to human health. Animal experiments can be misleading. An animal's response to a drug can be different than a human's. The stress that the animals endure in labs can affect experiments, making the results meaningless. Animal tests do not protect the consumer from the sale of dangerous drugs and substances because it is impossible to reliably predict human reactions in animals. There are countless biological variations between all species of animals.

According to Dr. Arie Brecher, M.D., head pediatrician in Holon, Israel,

"Animals are completely different from humans, and no animal species can serve as an experimental model for a human. Each animal has a genetic code of its own...and [is] characteristically unique in each species. For this reason, a method that is based on the similarity between the species, while there are differences, and different genetic codes, can only lead medical science into error." [Brecher, 1989]

Some examples of inaccurate animal testing: Sheep can consume enormous quantities of arsenic, which is fatal to humans in small amounts. A dose of belladonna that would kill a person is harmless to rabbits and goats. Hemlock is a deadly poison for humans, but is consumed without ill effect by mice, sheep, goats, and horses. These examples are typical of the wide range of reactions that occur between species, and the clearly demonstrate the danger of using animals to "safety test" drugs intended for human use. Often times even two closely related species, like mice and rats, react in entirely different ways. Animal tests have already caused irreparable damage. Drugs like Thalidomide, Phenylbutazone, and even cigarettes, which were first tested for "safety" on animals, have killed over 10,000 humans each. Mothers who took Thalidomide to ease morning sickness gave birth to children with deformities, with most lacking developed limbs. Animal tests had not predicted this.

Not only do inaccurate animal tests allow unsafe drugs to pass to human hands, but also keep drugs that would be beneficial to humans off the market. Some examples: Furosemide: 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; Prilosec: The release of this gastrointestinal medication was delayed for 12 years because of an effect in animals which did not occur in humans.

Problems with irritancy tests

However, the tests are also inaccurate. In one study the same 12 substances were tested for eye irritancy in 24 well-established laboratories. Since the same substances were being tested, using the same method, and the same species of animal, you would expect scores for the degree of eye injury to be similar. On the contrary, scores varied between rabbits in the same laboratory and varied widely between laboratories. Some substances that were rated as most irritating by some laboratories were rated as least irritating by others.

There are a number of differences between rabbit and human eyes:

Rabbits have a third eyelid, Rabbits produce less tear fluid to wash away irritants, Rabbits have a more alkaline eye (human pH 7.1-7.3, rabbit pH 8.2), and Rabbits have a thinner cornea (human 0.51mm, rabbit 0.37mm)

One study compared information about accidental human exposure to products with the results of animal tests using rabbits and monkeys. All animal tests, especially the standard Draize test, overestimated how irritating a product was to the human eye.

An experienced toxicologist has concluded:

"No single animal species has been found to model exactly for the human eye, either in anatomical terms or in response to irritation".

There are also considerable differences between human and rabbit skin. When 12 substances were tested on human and rabbit skin, results were similar only for the 2 most irritating products.

The remaining 10 products were irritating to the rabbits but not the humans.

In another study, a range of household products and industrial chemicals were tested on the skin of rabbits, guinea pigs and humans. Only 4 of the products were non-irritating in all 3 species. However, 12 products were more irritating in one or both of the animal species than in humans. A further 3 products were less irritating in one or both animal species than in humans.

The researchers concluded:

"Neither the rabbit nor the guinea pig provides an accurate model for human skin. The skin responses of these animals differ in both degree and in kind from those of human skin."

Problems with the LD50 test

It gives no information on treating human poisoning. It is an unreliable way of predicting risk to humans because the results are altered by so many factors. Firstly, there are huge species differences. Ten-fold species differences are common. In other words, the LD50 for the same substance is often 10 times higher in one species than in another.

There can be large differences even between closely related species. For example, the LD50 for paracetamol was 250-400mg/kg in mice and hamsters. Death was caused by liver damage. However, in rats the LD50 was 1000mg/kg, and there was no sign of liver damage.

Even within the same