by Jerome Burne
Guardian Unlimited | The Guardian | Animal testing is a disaster
http://www.guardian.co.uk/comment/story/0,3604,495634,00.html
Thousands of people have been injured or killed by drugs
that were found to be safe for other species
What do you feel is more important -- the life of your
child or the life of a few rats? Such stark contrasts are common
currency in the heavily polarized debate about experiments on animals.
On the one side the misguided sentimentality of the animal rights
campaigners, on the other side the tireless pursuit of human happiness
and health by the researchers.
But since those wide-eyed activists have put animals'
rights somewhere on the election agenda, you may be interested to know
that there is a totally hard-headed and rational case to be made for
saying that animal experimentation has been a scientific and medical
disaster. That far from saving lives, it has caused injury and death to
thousands and that time and again it has led both researchers and
legislators into a blind alley.
But surely, you cry, we need animal experiments to
discover how safe new drugs are before we give them to humans? Well, the
combination of fenfluramine and dexfenfluramine, touted as the answer to
a dieter's prayer a few years ago, was extensively tested on animals and
found to be very safe. Unfortunately it caused heart valve abnormalities
in humans. Or how about the arthritis drug Opren? Tests on monkeys found
no problems but it killed 61 people before it was withdrawn. And as for
having to choose between rats and your child, Cylert, given to children
with attention deficit hyperactive disorder, was fine for animals but
caused liver failure in 13 children.
The problem is not a new one, in fact it is blindingly
obvious -- animals are not the same as humans, so drugs that affect them
in one way may well affect us differently.
Now this is usually presented as a solvable problem by
researchers. We can get an idea of the mechanism from animals and then
fine-tune with humans, they say, but it doesn't work like that. Species,
even those that seem closely related, may function quite differently at
a molecular level,
and there is no way of predicting what the differences will be.
Rats and mice, for instance, look pretty alike to us,
but when it comes to something as basic as whether a chemical causes
cancer or not, the results may be totally contradictory. Out of 392
chemicals tested for carcinogenic effects at the American National
Institute of Environmental
Health Sciences, 96 were positive in the rat and negative in the mouse
or vice versa. So which of those are harmful to humans? The institute
can't say.
For 30 years they fed high doses of a range of new
chemicals to animals to discover if they caused cancer or other damage.
The results are recorded in blue books that take up 10 feet of shelving
in the institute. But ask how many of the substances might produce
tumors in humans at normal levels and no one knows. So what about the
ones that didn't harm rodents, how many of them might harm humans? They
don't know that either.
The lack of predictable differences between animal and
human reactions is something that has bedeviled Aids research. Aids is a
high profile disease with a lot of research money available, so it
surely makes sense to ignore ethical objections and use chimpanzees. It
is surely precisely
because their genome is identical to ours, give or take a few percentage
points, that they should yield more accurate results than rodents.
Well, no, actually. Out of approximately 100 chimps
infected with HIV over a 10-year period only two have become sick. Chimp
vaccine trials have proved unreliable too because they don't show the
antibody or cell-mediated response to HIV that humans do. Animal
experimentation has played only a small role in developing drug
treatments to the greatest plague of our time.
And the list could go on. There are drugs that have been
held back because they caused dangerous reaction in animals, such as
beta blockers and valium, but then turned out to be safe for humans.
Legislation to halt the use of asbestos was held up for years because it
didn't cause
cancer in animals, while the carcinogen benzene continued to be used
long after clinicians were worried because it didn't cause leukemia in
mice.
All these examples, and many more, have been written up
in the specialist journals but until last year they had been scattered.
Then a man called Ray Greek, an American medical doctor who specialized
in the highly technical field of anesthesia collected them in a book
called Sacred Cows and Golden Geese. He gave a talk in London about it
last night.
So was this scientific, rational contribution to the
debate about animal experiments warmly welcomed, so medical research
could be improved? Supporters of animal experiments are always calling
for more public discussion and education.
Of course not. It was ignored.
• Jerome Burne is editor of the monthly newsletter
Medicine Today
www.medicine-today.co.uk
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