and we probably should not have proceeded to overcome the difficulties of producing the substance for trial in man.'16 Indeed, Alexander Fleming who actually discovered penicillin, is reported as saying, 'How fortunate we didnít have these animal tests in the 1940s, for penicillin would probably not have been granted a licence, and possibly the whole field of antibiotics might never have been realised.'20
Despite the risks to human health, many animal toxicity tests have proved resistant to change. The 'safety explosion' of the 1960s meant that animal experiments became big business as private contract laboratories were established to conduct the huge number of tests. In addition to these commercial vested interests, there was also a reluctance by government regulatory authorities to change procedures once they had become enshrined in national and international guidelines. Companies tend to follow the guidelines when introducing new products since it may be too expensive to risk official rejection of a submission.
Animal Disease Models
Species differences are not restricted to the toxic effects of drugs and chemicals; similar problems arise when animals are used to investigate disease and identify treatments. Here, the illness or its symptoms are induced to produce an íanimal modelí of the human disease. Again, there are physiological and biochemical differences between humans and animals whilst the artificial production of lesions in otherwise healthy creatures further invalidates the method.
An example is stroke research where animal experiments have an abysmal record in predicting clinically useful treatments.21 Although barbiturates are effective in animals with artificially induced stroke, they provide little or no protection to human sufferers.16 In contrast, the drug nimodipine can treat a specific form of the disease in people yet fails in cats and baboons.22 Stroke researchers are in fact divided over the relevance of animal tests and some argue that 'over reliance upon such (animal) models may impede rather than advance scientific progress in the treatment of this disease. . . Each time one of these potential treatments is observed to be effective based upon animal research, it propagates numerous further animal and human studies consuming enormous amounts of time and effort to prove that the observation has little or no relevance to human disease or that it may have been an artifact of the animal model itself.'21
Mice and rats constitute 98% of the animals used for cancer research1 yet a Senior Investigator at the National Institutes of Health in Bethesda acknowledges how 'Many therapies that work in rodent tumour models have failed in the therapy of human tumours.'23 One survey estimates that for every 30-40 drugs effective in treating mouse cancers, only one will work in people.24 The high failure rate suggests that during clinical trials many cancer patients will be exposed to the severe toxicity of anti-cancer drugs without any corresponding benefit. In contrast, the steroid prednisone is an important >>
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