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Pressure is building on the US and Japan to abandon the LD₅₀
toxicity test. The test, which involves finding the dose of a chemical needed to
kill half a population of laboratory animals, has long been attacked as cruel
and unnecessary. The two countries are now the only major industrialised nations
which still require the test as part of standard toxicity testing for new
chemicals. Last month, Britain said it would no longer issue licences to conduct
LD₅₀ tests where alternatives are available.