The Draize rabbit eye test is a classic example of the mindset and lack of imagination that can delay the development of alternatives. Since 1944, this procedure has been employed to test the irritancy of a wide range of chemicals including pesticides and consumer products. Usually no pain relief is given and the experiment can proceed for 7 days during which the cornea, iris and conjunctiva are monitored for signs of opacity, ulceration, haemorrhage, redness, swelling and discharge. It had long been recognised that the rabbit eye is a poor model for the human eye, but toxicologists simply suggested using different species. Only during the 1980s, when animal protection groups focussed attention on the test, did attitudes finally start to change. Since then, dozens of in vitro techniques have been devised and some are now routinely used.
One of the most successful is EYTEX which is available in the form of a kit and can take as little as one hour to perform. Irritant chemicals produce turbidity, or cloudiness, in a mixture of plant proteins which mimics the corneal opacity produced in a living person or animal. The turbidity is easily measured using an optical instrument. EYTEX was developed by America's National Toxicology Corporation as 'a practical alternative to in vitro (live animal) methods.' It can rapidly identify moderate to severe eye irritants.(37) In addition, a human tissue system which models the outer layer of the cornea can distinguish between innocuous, mild and strong eye irritants whilst a combination of results from two other in vitro systems has been accepted by German regulatory authorities for identifying severely irritant chemicals: one of these uses the chorio-allantoic membrane of the hen's egg and the other utilises a cell culture assay.(38)
The Draize campaign encouraged scientists to be more positive towards alternatives with the result that far fewer animals are now used. In Britain during 1980, 13,294 rabbits were subjected to eye irritancy tests, falling to 4,216 a decade later.(39) Another way of focussing the scientific mind is for humane research organisations to fund research into alternatives to specific animal tests. For instance, an early award by Britain's Lord Dowding Fund helped develop quantum pharmacology, a theoretical technique for predicting the useful effects of drugs. Funding had been difficult to obtain as the method was considered speculative, but when the initial studies proved successful, sponsorship was taken up by government and industry. Now quantum pharmacology is an established part of drug design. From 1989 animal welfare organisations contributed to the Swedish-based MEIC programme for assessing in vitro toxicity tests. Many laboratories took part in the study which showed that human cell cultures could predict harmful effects in people.(40) And more recently, the Alternative Research and Development Foundation, a department of the American Anti-Vivisection Society, has funded research into a tissue culture method for producing monoclonal antibodies, substances traditionally made using a painful procedure with mice. Monoclonal antibodies are widely used for research and medical diagnosis.
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