THE American scientist behind research that triggered a scare surrounding salmon has pulled out of a conference in Scotland on legal advice and decided not to defend publicly the controversial study that resulted in a major sales decline.

David Carpenter is facing possible action over a claim he made with colleagues that Scottish farmed salmon was contaminated with high levels of cancer-causing particles.

The decision by Dr Carpenter, who had been due to deliver a paper next week, has caused the late cancellation of the event at the Royal College of Surgeons of Edinburgh.

Yesterday the director of the Institute for Health and the Environment at the State University of New York at Albany, who has been described by one US think-tank as a ''health scare hyperventilator'', was said by his office to be ''out of town'' and not contactable.

A spokeswoman there said: ''It is correct that he is not travelling to Scotland.''

Other conference speakers, including John Webster, scientific adviser at Scottish Quality Salmon (SQS), which is taking legal opinion

over what it called ''a highly sensationalised'' report, were told the conference had been scrapped because of his non-attendance.

They were told in an e-mail by a consultancy company which signed up Dr Carpenter to face the Scottish industry and UK media in the wake of the international furore caused by the research, that his decision had been taken on the advice of colleagues, lawyers and his university.

The e-mail said: ''We are extremely sorry to have to cancel this opportunity for a scientific debate on what is a very serious issue within the scientific community and the salmon industry.''

Dr Carpenter was one of several academics who carried out a scientific study of farmed Atlantic salmon.

Their report, published in the American journal Science, claimed that eating too much of it could possibly cause cancer and that it contained a cocktail of chemicals and toxins, including polychlorinated biphenyls. It recommended that people eat the fish no more than three times a year.

It singled out children, particularly young girls, and child-bearing women as being at risk.

The adverse publicity caused a large drop in sales of Scottish farmed salmon, the biggest impact said to be in France, Scotland's biggest export market.

Scottish salmon farming supports about 7000 jobs, 70% of which are in the Highlands and Islands. It injects (pounds) 2m a week into the economy

A spokeswoman said yesterday that SQS was still waiting for a final legal opinion before deciding whether to take action against the authors of the report.

''It is a complex issue because we are dealing with the whole industry. It will likely be a couple of weeks before we know exactly how that will take shape.''

She said the industry had been upset by the ''international PR campaign'' surrounding the research and the ''very sensationalised headlines''.

Normally, she said, such reports and research were put into the scientific domain and the industry involved given the opportunity to put its opinion.

''It's not normal for an industry to be the last people to hear about it,'' she added.

She said that SQS's view of the study had been supported by a number of international watchdogs including the World Health Organisation and the Food Standards Agency in Scotland.

It is understood that Label Rouge, the French government's food quality assurance scheme, may also be planning legal action.

Dr Carpenter had been asked to speak at a conference in Strasbourg at the end of next month, organised by the European Parliament.

However Struan Stevenson, the Scottish MEP and president of its fisheries committee, has indicated that he now expected Dr Carpenter to decline the invitation since he understood litigation was ''imminent''.