The drug industry is poised to abandon one of its commonly used but most controversial laboratory tests, accounting for 500,000 animal experiments as year.
A clear indication that firms making pharmaceuticals and cosmetics are prepared to drop the test came at a conference yesterday of the Fund for the Replacement of Animals in Medical Experiments (Frame), held at the Royal Society in London.
Scientists from some of the main commercial drug companies agreed by a show of hands with a proposal that the LD50 (standing for Lethal Dose 50 per cent) test should be dropped as a routine safety experiment. No one among the 600 delegates defended its continuance.
But animals will continue to be subjected to the LD50 test until it is removed from the government guidelines for regulations on the manufacture and marketing of pharmaceuticals, pesticides and herbicides, and food additives.
The unorthodox procedure at a scientific meeting of sampling came after papers had been given by senior industrial scientists. They included Dr V. K. H. Brown, of the Shell Toxicology laboratory, Sittingbourne Kent, Dr John Fowler, ICI Pharmaceutical Division, and Dr M. L. Tattersall, Pharmaceutical Division, Fisons.
They outlined progress in the use of animals and the alternative methods for conducting a category of safety test referred to as acute toxicity evaluation.
While they have not found alternatives to animals for all their work in the assessments, they all showed that LD50 tests have little value in acute toxicity studies, and that is the category which accounts for many animal experiments.
Eleven other categories of safety testing for which alternatives to animals are being sought are under review at this three-day meeting.
But it is the work using LD50 which has been shown to be of the least use. The test is done to discover the level at which a single dose of a substance will kill 50 per cent of a group of animals. The usefulness of the information obtained in that way for drug prescription, or food safety, is at best marginal.
The delegates to the Frame meeting are debating a preliminary report from a group of doctors, and academic and industrial scientists, on measures to avoid unnecessary animal experiments and to stimulate research on replacements.
Dr Michael Balls, of Nottingham University Medical School, chairman of the Frame Toxicity Committee, suggested that animal experiments could be reduced also by lifting restrictions on commercial secrecy of some research and by similar methods.
