Genetics row fuelled by scorpion's venom: Scientists express concern at 'fast track' clearance for experiment and claim measures taken to protect the trial site are inadequate. Susan Watts reports

A CABBAGE FIELD in the Oxfordshire countryside is set to become the site of a controversial genetic test on a modified viral pesticide.

The field, belonging to the Oxford University farm, is a bare- earth site, 30 by 80 metres. It is divided into 360 sub-enclosures, covered in fine nylon netting and fenced 'to keep out large mammals'. But the mammals most likely to threaten the security of the site - leading to a risk of an unintentional release of the virus into the wild - are humans. The researchers were told not to label the field for fear of attracting extreme environmental activists.

Britain has an unrivalled reputation for rigorous consideration of the risks and benefits of genetic tests outside the laboratory before they are given the go-ahead. The scientists objecting to the experiment - including Steve Jones, professor of genetics at University College London and the 1991 Reith lecturer - concede that the risk to the environment and to precious ecosystems at nearby Wytham Woods is small.

However, they question the risk assessment carried out by the Institute of Virology scientists conducting the research. They are also concerned that safety clearance of the tests was placed on a new 'fast track' system because similar tests had already been carried out in previous years.

George McGavin, lecturer in zoology at Trinity College, said the researchers did not appear to know what the engineered virus would do once it was released.

The scientist leading the research, David Bishop, insists the virus will not infect insects other than the caterpillars against which it is targeted. Yet in an advertisement in a local newspaper on 5 March, the scientists say the purpose of the releases is to 'look at the effect of the genetically modified virus on alternative hosts and its longer-term survival in the environment'.

It is this apparent contradiction that has made other scientists uneasy. 'Viruses undergo very rapid evolutionary changes and it is this very facility that makes them such successful organisms. Of the baculoviruses, the specific virus they are using, Autographa Californica, has one of the broadest host ranges,' Dr McGavin said in a letter to Dr George Smith, a resident of nearby Eynsham village who is co-ordinating objections.

The objectors' key concern is that arrangements for keeping the virus inside the test field are inadequate. But Professor Bishop, who has years of experience in similar tests both inside and outside the laboratory, is convinced they are sufficient.

Dr Smith has sent recent research material to the government safety committee that approved the Oxford work, including a paper published in January in the Proceedings of the National Academy of Sciences which indicates how broad a range of species the virus in question can infect - more than 40 different species of caterpillar belonging to 11 different families. He has also gathered evidence that, in the wild, the engineered virus may combine with natural viruses, increasing its range still further.

Professor Bishop concedes that the risks can never be completely eliminated, but said there had been no detectable problem in eight years of research. He said that, even if birds were to pick up and carry stray caterpillars, or eat them and defecate infected remains, the risk would be minimal in relation to populations. He said all the team's laboratory tests had backed up its assessment that the chances of the virus spreading are tiny. 'Now we want to test it in the field,' he said.

However, Dr McGavin warned in his letter to Dr Smith: 'While the biological control literature cites some spectacular success stories, it is also littered with cases of failure and surprising events such as biocontrol organisms not doing what they were supposed to do despite all the evidence to the contrary.' He urges caution. 'I think there are far too many doubts and unanswered questions to let it go through unchallenged,' he said in his letter.

Leading article, page 15

(Photographs and map omitted)