28 April 1995

Possible OP/BSE link to be studied

SCIENTISTS are to test a theory that BSE, is linked to exposure to organophosphorus chemicals.

South-west farmer, Mark Purdey, whose OP theory has been dismissed by MAFF experts, said scientists at the Medical Research Council will be involved in a "preliminary trial" to test the link.

Mr Purdey said the go-ahead for the work meant he, at last, had "strong support from the establishment". But he had repeatedly been told by MAFF scientists that the trial, which takes a few minutes to do and costs about £600, was impossible to carry out.

It will test whether normal prion protein present in animals can be deformed by OP exposure. MAFF research has already shown that abnormal forms of this protein are a unique feature of all transmissible spongiform enceph-alopathies, including BSE. These "mutant" proteins occur in the brain, spleen and lymph nodes of clinically-affected animals.

The trial will determine whether OP can bind to normal prion protein and then convert it into the "mutant" version. If this is the case it will also test whether the deformed protein is itself the BSE agent and if it is infectious.

Mr Purdey believes BSE is linked to the use of the OP chemical phosmet, used in MAFFs warble fly eradication campaign. He said farmers were advised to treat cattle with more than four times the recommended dose. The products were withdrawn from the market in 1989, 1990 and 1991, which, Mr Purdey says, fits with the declining number of BSE cases in cattle born in those years.

But a recent MAFF report says delayed damage to nerves induced by OPs "are clearly distinguishable from those in BSE". It adds that "many other countries without BSE use OP compounds and, contrariwise, Guernsey, on which island OP compounds are not significantly used, does have BSE". &#42

Liz Mason