The BBC's Margaret Gilmore: "Even low exposure is a health risk"

The findings come in a report from the Edinburgh-based Institute of Occupational Medicine.

Deputy Agriculture Minister Jeff Rooker said they are to be sent to the government's expert advisory committees for urgent consideration and further advice.

The report adds to the weight of evidence of organophosphate (OP) sheep dips posing a risk to health.

'Genuine health problems'

Last November, the Royal Colleges of Physicians and Psychiatrists published research saying that people exposed to (OP) dips can suffer "genuine and often very severe" symptoms.

Jeff Rooker: "We will take effective action"

Two years ago 60 sheep dippers in the Western Isles were found to be suffering from the chronic fatigue syndrome ME - four times the national average.

Farmers who say exposure to the dips has affected their health complain of symptoms including excessive tiredness, headaches, limb pains, disturbed sleep, poor concentration, mood changes, and thoughts of suicide.

The government had instructed farmers to use sheep dip containing organophosphates between 1976 and 1992, but since then their use has been optional.

However, despite growing evidence of a link between ill health and their use, they have never been banned.

Jeff Rooker welcomed the research

In a written reply to a Parliamentary question, Mr Rooker acknowledged publication of the report which studied about 600 farmers at a cost of £500,000.

He said: "This is a timely and important piece of research by the Institute of Occupational Medicine.

"The report identifies handling of OP sheep dip concentrates as the main source of potential exposure.

"It suggests that the identified exposure to concentrates was associated with an increased likelihood of ill-health in the groups studied.

Difficult issues

"The study looks at complex issues and requires careful evaluation by scientific experts in this area.

"That is why my colleagues and I have agreed that the Committee on Toxicity (COT) Working Group on OPs should consider this report along with the substantial body of evidence they have been examining on the possible ill-health effects of OPs.

"I have also asked the Veterinary Products Committee and the Advisory Committee on Pesticides to consider urgently whether the study affects their advice on the safety of OPs and whether further measures are necessary in advance of the completion of COT's review.

"In addition, I have today written to the representatives of the manufacturers seeking a meeting within the week to discuss what action they will be proposing in response to the report, in particular to the findings on concentrates.

"It is important that those who use OPs continue to follow all safety precautions and are competent in knowing how to use them."

Acting on evidence

The government expects the committees to report back by the end of this year.

Mr Rooker earlier indicated that cash could be made available to fund further research into the subject.

Paul Tyler, for Liberal Democrats and chairman of the all-party group on OPs, said fast action was needed "to assist those whose lives and livelihoods are frankly being ruined by exposure to these very dangerous chemicals".

Western Isles MP and Scottish Office Minister Calum MacDonald, along with Friends of the Earth Scotland, had raised worries the study would not look fully at psychological disorders linked to the chemicals.

They were also concerned that the true extent of OP-related illness would not be detected.

Pete Riley, agricultural campaigner at Friends of the Earth, said the report highlighted nothing new.

He said: "The links between the use of OPs and sickness have long been known by everyone.

"We are looking for a ban on the use of OPs, but we want to see that as part of a series of measures which will protect the environment as well as protecting farmers' health."