Jonathan Leake, The Sunday Times-Britain

FARMERS could be forced to curb spraying of toxic pesticides after a report from leading scientists warning that the chemicals could be poisoning tens of thousands of people living or working in the countryside.

The Royal Commission on Environmental Pollution has spent the past year investigating claims that the 31,000 tons of chemicals sprayed on Britain’s farms each year are a toxic threat to humans.

Until now government scientists and the pesticide industry have dismissed reports of miscarriages, elevated cancer rates and other diseases among those exposed to pesticides. Next week, however, the RCEP’s final report will say that such fears could be justified.

It is expected to demand new safety rules for farmers and ask the government to carry out detailed research into the chemicals’ impacts.

It will also compare intensive arable farming with factories, saying that while industrial emissions have been regulated for decades the exemption of farmers from similar rules is anomalous.

If implemented, the report would be a victory for Georgina Downs, who has led a campaign to overhaul pesticide regulations. It was her pressure that persuaded ministers to involve the RCEP.

Downs, a former singer, started the UK Pesticides Campaign after being diagnosed with serious health problems including osteoporosis and neurological problems. Downs’s home near Chichester, West Sussex is surrounded by farmland that is sprayed regularly. When doctors said the damage could be due to pesticides she vowed to fight back.

This weekend she could not comment on the unpublished report but added: “The government has failed to protect people in the country from pesticides. There should be a ban on crop spraying near homes, schools and workplaces. Farmers should be legally obliged to warn communities and visitors to the countryside about any intended spraying.”

Pesticides are designed to kill at low concentrations. They destroy insects, weeds and other pests but most are also toxic to humans.

Official reports warning of the danger were published by the Commons agriculture select committee and the British Medical Association.

Those reports said farmers should be forced to pass exams in the use of such chemicals before they were allowed to buy them. Successive governments have, however, done little.

The RCEP report is likely to demand farmers warn residents before spraying and leave buffer zones around the edges of fields close to homes or other buildings such as schools. The size of such buffer zones has been a crucial issue for Downs, who says it should be at least a mile. A study in California found pesticides spread up to three miles from where they were initially applied.

Professor Vyvyan Howard, a toxicologist who sits on the advisory committee on pesticides, which approves such chemicals for use, said: “The biggest threat is to developing children. A foetus can be affected by such tiny traces of chemicals, in concentrations as low as parts per trillion, that no exposure can be safe.”