How reliable are animal experiments? Exposing failure rates from animal labs
How Reliable Are AnimalExperiments ?Uncovering the failure rates from animal labs An inquiry into animal experiments is long overdue, as there has never been a formal evaluation of animal testing.However, there have been smaller scale statistical studies, and theymake interesting reading.Drug TestingAnimal experiments are an established method of safety testing medicaldrugs. Although this was never evaluated before the method wasadopted, adequate data is available.Animals of various species are used to screen drugs for potentialunwanted reactions. Given that it is normal practice to use a number ofspecies, it might be expected that if animal experiments were predictive,this method would identify potential dangers. Animal experiments were evaluated by animal experimenters, who took six drugs, and noted which of the 78 adverse effects were detectable in dogs or rats. They ignored the effects which were undetectable in animals (e.g. headaches). Less than half (46%) of the remaining side effects were detected in the animals - slightly less than the expected results from flipping a coin. In other words, animal tests were wrong 54% of the time.
54% failureWith such a high failure rate, it might be expected that a high proportionof side effects caused by drugs would go unpredicted by animal tests.With this in mind, the American Food & Drug Administration (FDA)monitored all the drugs approved over a ten-year period. Of 198 drugs monitored, 102 (52%) were re-labelled or withdrawn due to unforeseen effects. As some of the side effects that were predicted would have been discovered by pre-approval human trials, the success rate of animal use can be safely assumed to be well below the 48% discovered by the FDA. 52% failureAn international authority on the matter who represented the Worldhealth Organization failed to put a figure on the success rate of standardvivisection practice when he stated: "Most adverse reactions which occur in man cannot be demonstrated, anticipated or avoided by the routine subacute and chronic toxicity experiment."Where he avoided estimating a percentage, Dr Ralph Heywood did not.As Scientific Executive of Huntingdon Research Centre (now HuntingdonLife Sciences), one of the largest animal labs in Europe concerned withscreening drugs, he estimated that:
"…the best guess for the correlation of adverse reactions in man and animal toxicity data is somewhere between 5% and 25%."  75%-95% failureInterestingly, his estimation of a maximum of 25% is agreed on by Dr APFland: As a very approximate estimate, for any individual drug, [only] up to twenty-five per cent of the toxic effects observed in animal studies might be expected to occur as adverse reactions in man. More than 75% failure This has terrible consequences, whihc you can read about here.But sometimes the reverse is true. Unwanted effects may be predicted byanimal studies, when they do not affect humans. For example, the firstchemotherapy drug, Actinomycin-D, was discovered without animal use.Later it was tried on animals and found to kill many species, includingmonkeys. This did not relate to humans. This is common: 45 drugs tested in 1978 were analysed. Of the side effects predicted by animal studies, 75% did not happen in humans.
75% failureAlong with the matter of whether a drug is actually effective or not, thesafety profile of a potential new drug is assessed first on animals, thenprogressing to human trials if successful in animals. So the success rateof animal tested drugs in humans can again be evaluated by examiningthe progress of these medicaments. The Pharmaceutical Research and Manufacturers of America estimate that of the drugs presented to human trials, 5% are eventuallyapproved. 95% failureThe human trials are in three stages. The first trial involves healthyhuman volunteers, typically about 20-80. At this stage eleven out of twelve animal-modelled drugs fail. 92% failureAn example of this - an example which has produced statistical evidence -is the case of stroke drugs. In the periods 1978-1988, twenty-five drugs were found to treat stroke in animals. The number that worked in humans was found to be zero. 100% failure
Twenty-two drugs to treat spinal cord damage were developed on animals. None worked in humans. 100% failureAn approach such as animal experimentation to discovering drugs can belikened to gambling. Occasionally - through sheer chance - it may givethe correct result applicable to humans. But it cannot be relied on. Afamous pharmacologist said on accepting a prize for his work that is it "amatter of pure luck that animal experiments lead to clinically usefuldrugs". He was among those who used animals for exactly that when hesaid this.Why dont animal methods work for predicting drug reactions? Thesimple answer is that animals are different. A major difference is thatthey suffer from different diseases to us. Less than 2% of the illnessesthat can afflict humans are found in any other animal species. Somany of the diseases animal experimenters are trying to treat - as well asmany of the conditions which may be caused as a side effect of aprospective medication - may not exist in the test animal (or anyanimal). Dogs get distemper, humans do not. This is also why noanimals have developed AIDS in the same way that humans have.Animals also have different biochemistry, different diets, they dont live aslong as us (and the test periods are over short periods) - and theyprocess drugs differently. Vitamins affect different animals in differentways, and the drugs are digested and metabolised differently. Animal
experimenters have discovered that rats metabolise drugs in a differentway to humans in 83% of cases. Yet still they are a favourite tool fordrug testing and chemical screening. Why?Dr James G Gallagher was director of Medical research, LederleLaboratories, when he discussed "…an unscientific preoccupation withanimal studies." He went on to say "Animal studies are done for legalreasons and not for scientific reasons."It gets drugs onto the market, and provides evidence that something wasdone, therefore avoiding the charge of negligence when the inevitablehuman damage occurs.CancerAnother area where animal use is claimed to be essential is in cancerresearch. Animals are used to see which chemicals cause cancer, andwhich may help combat it.The screening of potential cancer-causing chemicals is a subject in whichvivisection has been evaluated. The drug company Pfizer did this in 1983. "The results would be vitally important because despite costing millions of dollars, no one really knew whether they provided adequate protection against hazardous substances. Human findings were compared with experimental data from rats and mice for all chemicals known to cause cancer in people. The outcome was disturbing: in most cases animal tests had given the wrong answer.
The report concluded that we would have been better off to have tossed a coin."The actual percentage of carcinogens identified was 36.8% 63% failureRats and mice are still overwhelmingly the most commonly used animals.But the use of other animals is no more successful. "Warning is given not to carry over, without reservation, to man, the conclusions based on animal experiments. In monkeys none of the power carcinogens [to humans] has been shown to produce cancers." 100% failureWhich means that approval by experiments on monkeys means nothingfor our safety. More data to evaluate the methods is available from thestudy or oral cancers: Nineteen chemicals known to cause oral cancer in humans were studied in animals. Using the standard National Cancer Institute Protocol, and rats and mice, twelve were found to be safe in animals. 63% failure
Also the reverse is true - substances identified as dangerous by animalexperiments are likely to be completely harmless. Of twenty compounds known not to cause cancer in humans, nineteen did cause cancer in the laboratory animal. 95% failureDifferences between species are so specific that even relatively similarspecies may show a different profile of reactions to test chemicals. Experiments on rats and mice show that 46% of chemicals which caused cancer in rats, were not cancer inducing in mice. Mice were found to develop cancer, due to exposure to chemicals which did not affect rats.Industry experts correctly conclude: "We would have been better off totoss a coin" Animal experimenters involved in the practice havethemselves evaluated their business as "a half-baked guess" and "allguess" (Dr Frederick Coulston).Animals are also used in attempts to detect drugs and plants that may beuseful in treating human cancers. Yet this has not been effective. As theexecutive director of cancer research at Merk Research Laboratorysummed up: "The fundamental problem in drug discovery for cancer is
that the model systems are not predictive at all". Model systems thatuse animals.The lack of success with animal models is not due to a lack of trying.Between 1970 and 1985, 500,000 different chemicals were tried onanimals in an attempt to find some which would combat cancer. From this mammoth operation, just eighty drugs were identified by the animal studies. Of these eighty, only twelve went on to make a different to the lives of humans. 85% failureAt a first glance this might seem to be a worthwhile exercise - somethingworthwhile came out of this massive project. Yet all of thesenew treatments were sufficiently similar to existing treatments that theycould have been identified from their chemical structure. Using noanimals and a fraction of the time and money, non-animal, human basedmethods could have had these drugs in use more quickly.A similar study, over 25 years by the National Cancer Institute (USA)tested 40,000 plant species for anti-cancer effects. All chemicals identified by the animal tests were either ineffective or too highly poisonous to be used in humans.Even the Handbook of Laboratory Animal Science admitted: "despite 25years of intensive research and positive results in animal models, not asingle anti-tumour drug emerged from this work."
100% failureOne of the major reasons for this is that the cancers that humans developare not the same as the animal cancers. With this in mind, experimentershave tried to improve their success rates by implantinghuman cancersinto mice. Known cancer drugs were used on the animals. In 30 of the 48 cases, the human drugs had no affect on the cancer, despite working in humans, and the cancers in question being human cancers. 63% failureThe species differences exist on too many, and on too subtle levels to bebypassed. As Irwin Bross, formerly of the Roswell Park Memorial Institutefor Cancer Research stated when giving evidence to the US Congress in1981: "…while conflicting animal results have often delayed and hampered advances in the war on cancer, they have never produced a single substantial advance in either the prevention or treatment of human cancer." 100% failureInstead, research has been led in the wrong direction, studying the wrongform of cancer in the wrong species."God knows weve cured mice of all sorts of tumours" said Thomas EWagner, a long-serving cancer research specialist. "But that isnt medicalresearch."
Why do they do this? Let someone who does this answer this question.Dr P Shubik was at a conference of cancer researchers who usedanimals. Many had openly criticised their work and stated howunscientific it was. "The chief objective is to keep us all employed, and to make sure we do interesting experiments so that we can come back to these nice places."Read more about cancer researchhere.Birth DefectsPerhaps the greatest fear among ordinary people is that of the damagedrugs can do to their unborn children. The example of Thalidomide,which caused thousands of serious birth defects, has been quoted as areason why animal experiments must be done - to stop it happeningagain.It has been claimed that thalidomide was never tested on pregnantanimals before it was given to humans, although this is unlikely. Animalexperiments were standard practice. It is undisputed that after thehuman disasters it was tested on animals. Countless species and sub-strains were used, including over 150 different breeds of rabbit. One species of rabbit produced malformed offspring when given Thalidomide - and that was at doses of 10
times the human dose. Salt or sugar in that dose would have caused the same problems. Animal experiments were - and still are - incapable of predicting that thalidomide is dangerous to pregnant humans. 100% failureExperiments have been conducted to evaluate whether animalexperiments are effective in showing which drugs can damage the unbornchild. Drugs known to damage the human foetus were given to animals. 55% passed tests on hamsters. 55% failure 70% passed tests on pregnant monkeys - our closest animal relative. 70% failureYet other drugs and chemicals have been identified to be dangerous topregnant mothers by animal experiments despite being harmless. Asreported in a medical journal, over 1,200 chemicals have been identifiedto cause birth defects in lab animals, yet only 30 cause birth defects inhumans. Many useful drugs are indicated dangerous in animals butare safe in humans, including aspirin and insulin. 97.5% failureThis estimate of 97.5% failure invites disbelief, but was arrived atindependently:More than eight hundred chemicals have been identified as teratogens inlaboratory animals, but only a few of these, approximately twenty, have
been shown to be teratogenic in humans. This discrepancy can beattributed to differnces in metabolism, sensitivity and exposure time.This is also 2.5%. 97.5% failureNow that animal experiments are an established, commonly used method,it is known that all drugs released have been tested on pregnant animalsfirst. Yet of all birth defects, an estimated 61% of them were estimatedto be caused by medical drugs, according to one of the most detailedstudies ever conducted. For stillborn babies, drugs are estimated tobe the cause in 88% of cases.Birth defect rates are rocketing. Over a 25-year period from 1948 to1973, they rose from 3 per 100,000, to 500 per 100,000. They arecontinuing to rise. Read more about this here.Evidence taken from the results of animal experiments enable us evaluatethe accuracy of their tests. Many good scientists expect that due to themassive differences in species, which can never be overcome, theaccuracy will be low. Other people have looked at the results and cometo a similar conclusion.The average of the percentages uncovered above is 20%. But even thisfigure may be flattering. Much of animal experimentation is attempting torecreate a condition already known. "…until somebody knew what to look for, they did not seek those things. To suggest that this process is predictive is somewhat of an anomaly in terms. It can hardly be predictive after the fact…"
If animal testing were abandoned today, there would be hundreds ofmethods we could use. The American National Cancer Institute aloneuses 100 cell culture tests to identify cancer-causing chemicals. Astechnology progresses we are able to develop more accurate methods.Gene therapy and computers are just two examples of areas wheremassive advances have been made using ingenuity and good science.All these methods have the advantage of being human-centred andtherefore can expect a degree of accuracy far in excess of the extremelylow levels achieved by animal experiments. 20% effectiveness is notscience. It is the sort of success rate achieved by the charlatan fortune-teller.Medical advances have been made throughout history by studyingpatients, observing results, studying cells and human tissue, autopsies,the use of mathematical techniques and computer modelling and studyingpopulations. These methods have been successful, while animalexperiments have been haphazard and have failed us.This article may be copied and circulated with the aim of educating more people of thefailure of vivisection.REFERENCES1 ClinPharmacolTher 1962; pp665-6722 GAO/PEMD-90-15 FDA Drug Review:Postapproval Risks 1976-19853 Prof G Zbinden, "Applied Therapeutics", 1966, 8, pp128-1334 Animal Toxicity Studies:Their relevance to man Lumley & Walker (ed) pp57-67, Quay,19895 Dr. A. P. Fland, Journal of the Royal Society of Medicine, vol.71, 1978, pp.693-696.6 AP Fletcher in Proc R Soc med, 1978;71, 693-8
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