THE four new tests approved by the OECD will have a major impact in reducing the numbers of animals used in toxicology studies. In Britain alone, these accounted for 17 per cent of the 2.7 billion animal procedures performed in 2000, the most recent year for which Home Office statistics are available.
Two of the new tests will save rabbits from a painful procedure designed to identify corrosive chemicals. Instead of dabbing chemicals onto a live rabbit鈥檚 skin, toxicologists can now do the same check by putting chemicals onto discs of skin cultured from humans or rodents. A third test is designed to show whether chemicals percolate through cultured skin, a test also previously done on live rats and mice.
The final procedure measures the 鈥減hototoxicity鈥� of chemicals 鈥� whether they become harmful when placed on the skin and exposed to sunlight. The chemicals can now be tested on mouse cells engineered to change colour under UV light if the substances are harmful. Phototoxicity tests have never been done before, however, so it won鈥檛 replace any live animals. 鈥淚t鈥檚 saving animals prospectively,鈥� says Gill Langley of the Dr Hadwen Trust for Humane Research.
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Pharmaceuticals and agricultural companies are also making strides in developing biochip and gene technologies that will end the need for live animal tests. Companies can screen for toxic drugs or agrochemicals by dabbing chemicals onto microscopic grids of genes or proteins. Increases in computing power are also helping weed out chemicals that have similar molecular structures to known toxins.
The underlying principle for doing away with animal tests is to work towards the 鈥渢hree Rs鈥�: reduction, refinement and replacement. The biggest gains so far have come from reduction and refinement 鈥� altering procedures so that fewer animals are needed to get the same result, with less suffering to the animals involved. But the ultimate aim is replacement: doing away with the need for animals altogether.