1. How Reliable Are Animal
Experiments ?
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 they
make interesting reading.
Drug Testing
Animal experiments are an established method of safety testing medical
drugs. Although this was never evaluated before the method was
adopted, adequate data is available.
Animals of various species are used to screen drugs for potential
unwanted reactions. Given that it is normal practice to use a number of
species, 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[1]. In other words,
animal tests were wrong 54% of the time.

2. 54% failure
With such a high failure rate, it might be expected that a high proportion
of 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 Of 198 drugs monitored, 102 (52%) were re-labelled or withdrawn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[2]. 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% failure
An international authority on the matter who represented the World
health Organization failed to put a figure on the success rate of standard
vivisection 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."[3]
Where he avoided estimating a percentage, Dr Ralph Heywood did not.
As Scientific Executive of Huntingdon Research Centre (now Huntingdon
Life Sciences), one of the largest animal labs in Europe concerned with
screening drugs, he estimated that:

3.  "…the best guess for the correlation of adverse reactions in man and
animal toxicity data is somewhere between 5% and 25%." [4]
75%-95% failure
Interestingly, his estimation of a maximum of 25% is agreed on by Dr AP
Fland:
 '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'.[5]
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 by
animal studies, when they do not affect humans. For example, the first
chemotherapy drug, Actinomycin-D, was discovered without animal use.
Later it was tried on animals and found to kill many species, including
monkeys. 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[6].

4. 75% failure
Along with the matter of whether a drug is actually effective or not, the
safety profile of a potential new drug is assessed first on animals, then
progressing to human trials if successful in animals. So the success rate
of animal tested drugs in humans can again be evaluated by examining
the progress of these medicaments.
 The Pharmaceutical Research and Manufacturers of America estimate
that
of the drugs presented to human trials, 5% are eventually
approved[7].
95% failure
The human trials are in three stages. The first trial involves healthy
human volunteers, typically about 20-80.
 At this stage eleven out of twelve animal-modelled drugs fail[8].
92% failure
An 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[9].
100% failure

5.  Twenty-two drugs to treat spinal cord damage were developed on
animals. None worked in humans.[10]
100% failure
An approach such as animal experimentation to discovering drugs can be
likened to gambling. Occasionally - through sheer chance - it may give
the correct result applicable to humans. But it cannot be relied on. A
famous pharmacologist said on accepting a prize for his work that is it "a
matter of pure luck that animal experiments lead to clinically useful
drugs". He was among those who used animals for exactly that when he
said this[11].
Why don't animal methods work for predicting drug reactions? The
simple answer is that animals are different. A major difference is that
they suffer from different diseases to us. Less than 2% of the illnesses
that can afflict humans are found in any other animal species[12]. So
many of the diseases animal experimenters are trying to treat - as well as
many of the conditions which may be caused as a side effect of a
prospective medication - may not exist in the test animal (or any
animal). Dogs get distemper, humans do not. This is also why no
animals have developed AIDS in the same way that humans have.
Animals also have different biochemistry, different diets, they don't live as
long as us (and the test periods are over short periods) - and they
process drugs differently. Vitamins affect different animals in different
ways, and the drugs are digested and metabolised differently. Animal

6. experimenters have discovered that rats metabolise drugs in a different
way to humans in 83% of cases[13]. Yet still they are a favourite tool for
drug testing and chemical screening. Why?
Dr James G Gallagher was director of Medical research, Lederle
Laboratories, when he discussed "…an unscientific preoccupation with
animal studies." He went on to say "Animal studies are done for legal
reasons and not for scientific reasons."[14]
It gets drugs onto the market, and provides evidence that something was
done, therefore avoiding the charge of negligence when the inevitable
human damage occurs.
Cancer
Another area where animal use is claimed to be essential is in cancer
research. Animals are used to see which chemicals cause cancer, and
which may help combat it.
The screening of potential cancer-causing chemicals is a subject in which
vivisection 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.

7. The report concluded that we would have been better off to have
tossed a coin[15]."
The actual percentage of carcinogens identified was 36.8%
63% failure
Rats 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."[16]
100% failure
Which means that approval by experiments on monkeys means nothing
for our safety. More data to evaluate the methods is available from the
study 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[17].
63% failure

8. Also the reverse is true - substances identified as dangerous by animal
experiments are likely to be completely harmless.
 Of twenty compounds known not to cause cancer in humans,
nineteen did cause cancer in the laboratory animal[18].
95% failure
Differences between species are so specific that even relatively similar
species 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[19].
Industry experts correctly conclude: "We would have been better off to
toss a coin"[20] Animal experimenters involved in the practice have
themselves evaluated their business as "a half-baked guess" and "all
guess" (Dr Frederick Coulston)[21].
Animals are also used in attempts to detect drugs and plants that may be
useful in treating human cancers. Yet this has not been effective. As the
executive director of cancer research at Merk Research Laboratory
summed up: "The fundamental problem in drug discovery for cancer is

9. that the model systems are not predictive at all"[22]. Model systems that
use 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 on
animals 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% failure
At a first glance this might seem to be a worthwhile exercise -
somethingworthwhile came out of this massive project. Yet all of these
new treatments were sufficiently similar to existing treatments that they
could have been identified from their chemical structure. Using no
animals and a fraction of the time and money, non-animal, human based
methods could have had these drugs in use more quickly[23].
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[24].
Even the Handbook of Laboratory Animal Science admitted: "despite 25
years of intensive research and positive results in animal models, not a
single anti-tumour drug emerged from this work."[25]

10. 100% failure
One of the major reasons for this is that the cancers that humans develop
are not the same as the animal cancers. With this in mind, experimenters
have tried to improve their success rates by implantinghuman cancers
into 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[26].
63% failure
The species differences exist on too many, and on too subtle levels to be
bypassed. As Irwin Bross, formerly of the Roswell Park Memorial Institute
for Cancer Research stated when giving evidence to the US Congress in
1981:
 "…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% failure
Instead, research has been led in the wrong direction, studying the wrong
form of cancer in the wrong species.
"God knows we've cured mice of all sorts of tumours" said Thomas E
Wagner, a long-serving cancer research specialist. "But that isn't medical
research."[27]

11. Why do they do this? Let someone who does this answer this question.
Dr P Shubik was at a conference of cancer researchers who used
animals. Many had openly criticised their work and stated how
unscientific 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."[28]
Read more about cancer researchhere.
Birth Defects
Perhaps the greatest fear among ordinary people is that of the damage
drugs can do to their unborn children. The example of Thalidomide,
which caused thousands of serious birth defects, has been quoted as a
reason why animal experiments must be done - to stop it happening
again.
It has been claimed that thalidomide was never tested on pregnant
animals before it was given to humans, although this is unlikely. Animal
experiments were standard practice. It is undisputed that after the
human 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

12. 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[29].
100% failure
Experiments have been conducted to evaluate whether animal
experiments are effective in showing which drugs can damage the unborn
child. Drugs known to damage the human foetus were given to animals.
 55% passed tests on hamsters[30].
55% failure
 70% passed tests on pregnant monkeys - our closest animal
relative[31].
70% failure
Yet other drugs and chemicals have been identified to be dangerous to
pregnant mothers by animal experiments despite being harmless. As
reported in a medical journal, over 1,200 chemicals have been identified
to cause birth defects in lab animals, yet only 30 cause birth defects in
humans[32]. Many useful drugs are indicated dangerous in animals but
are safe in humans, including aspirin and insulin[33].
97.5% failure
This estimate of 97.5% failure invites disbelief, but was arrived at
independently:
More than eight hundred chemicals have been identified as teratogens in
laboratory animals, but only a few of these, approximately twenty, have

13. been shown to be teratogenic in humans. This discrepancy can be
attributed to differnces in metabolism, sensitivity and exposure time.[34]
This is also 2.5%.
97.5% failure
Now that animal experiments are an established, commonly used method,
it is known that all drugs released have been tested on pregnant animals
first. Yet of all birth defects, an estimated 61% of them were estimated
to be caused by medical drugs, according to one of the most detailed
studies ever conducted[35]. For stillborn babies, drugs are estimated to
be the cause in 88% of cases[36].
Birth defect rates are rocketing. Over a 25-year period from 1948 to
1973, they rose from 3 per 100,000, to 500 per 100,000[37]. They are
continuing to rise. Read more about this here.
Evidence taken from the results of animal experiments enable us evaluate
the accuracy of their tests. Many good scientists expect that due to the
massive differences in species, which can never be overcome, the
accuracy will be low. Other people have looked at the results and come
to a similar conclusion.
The average of the percentages uncovered above is 20%. But even this
figure may be flattering. Much of animal experimentation is attempting to
recreate 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…"[38]

14. If animal testing were abandoned today, there would be hundreds of
methods we could use. The American National Cancer Institute alone
uses 100 cell culture tests to identify cancer-causing chemicals[39]. As
technology progresses we are able to develop more accurate methods.
Gene therapy and computers are just two examples of areas where
massive advances have been made using ingenuity and good science.
All these methods have the advantage of being human-centred and
therefore can expect a degree of accuracy far in excess of the extremely
low levels achieved by animal experiments. 20% effectiveness is not
science. It is the sort of success rate achieved by the charlatan fortune-
teller.
Medical advances have been made throughout history by studying
patients, observing results, studying cells and human tissue, autopsies,
the use of mathematical techniques and computer modelling and studying
populations. These methods have been successful, while animal
experiments have been haphazard and have failed us.
This article may be copied and circulated with the aim of educating more people of the
failure of vivisection.
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