20 February 1998

OPuse moratorium call as new risks revealed

By Jonathan Riley

ORGANOPHOSPHATE specialists have called for a moratorium on the use of OP-based pesticides.

Speaking at a House of Commons briefing, leading OP scientist Goran Jamal said new research suggested that producers could be at greater risk than previously thought.

"There is a greater risk for those handling pesticides in hot weather and when under physical and emotional stress," said Dr Jamal.

He explained that the barrier between the blood system and brain was thought to act like a checkpoint, allowing some substances through while preventing toxins reaching the brain.

"But in hot weather, and under conditions of stress, the blood/brain barrier is 100 times more permeable and toxins are more likely to pass through unchecked.

"Anyone who has dipped sheep will know that physical and heat stress are common at dipping times. And this, therefore, increases the likelihood that OP metabolites can reach the central nervous system," he said.

He also revealed that long-term effects of OP poisoning had been documented in trials on eight volunteer servicemen at the Ministry of Defence research station at Porton Down.

The trials monitored the effect of OPs after being applied to the volunteers hands and showed that effects from a single dose lasted for at least 30 months.

Andrew Watterson, director of De Montfort Universitys institute for occupational health, said the safety of OPs had been questioned for many years and he called for a moratorium on pesticide sales.

"We at least need a period where we can fully assess the safety of products and the effectiveness of protective equipment," said Prof Watterson.

He quoted from the current Health and Safety Executive guidance note MS17which states that acute exposure to OP pesticides can produce harmful effects in man, and repeated exposure at lower doses may cause insidious cumulative toxicity.

But, this document had not been widely circulated and few doctors had adequate information to deal with patients claiming to be affected by OPs.

"We cannot continue to sell these products without more information on their safety and the effectiveness of protective equipment," he said.

&#8226 Dr Jamal is to rejoin the medical and scientific panel of the governments veterinary products committee. He originally resigned in Dec 1996 after refusing to sign a MAFF agreement preventing panel members from giving evidence in court on the effect of OPs on human health. But farm minister Jeff Rooker has waived that requirement to allow Dr Jamal back on to the panel.