What exactly is genetic modification anyway? How - and when - did it all begin? Setting the scene for Tuesday's Herald Foodfuture question time on gm foods, Catherine Brown charts the development of one of today's most urgent food issues.

While the discovery of how to alter the genetic make-up of living organisms could change the way we deal with pollution, drug production and sewage control, its effect on the food we eat could be equally dramatic. Not since ''new world'' novelties such as sweet peppers, maize, chocolate and potatoes crossed the Atlantic, around five centuries ago, has the world's population faced such a potential upheaval in its food supplies.

The laboratory testing of gene transfer from one living organism to another began in the 1970s, though the first breakthrough took place in 1953 when the structure of nucleic acid in chromosomes was discovered and

the gene message in DNA (deoxyribonucleic acid) was found to provide the blueprint or code for the cell.

Laboratory pioneering of GM foods in the 1970s established their commercial advantage and it was not long before patents were being sought for the new discoveries. In 1980 the first genetic modification case in the US Supreme Court (Diamond v Chakrabarty) ruled that engineered ''living things'' could

be classified as ''inventions' rather than ''products of nature'.

It was viewed as a test case for patenting GM organisms and opened the floodgates.

Genes became currency.

By the end of the 1980s Europe was also accepting the concept of patenting new gene developments but by now doubts were also being expressed. In 1989 there was an epidemic of what seemed like a new disease in the US (ecosinophilia myalign syndrome) which was traced to the consumption of a brand of tryptophan food supplement which had been made from a GM bacteria.

The process had produced a new toxin and 37 died, while 1500 were permanently disabled. The product was not labelled as being derived from GM bacteria and it was several months before the cause of the tragedy was eventually explained. The only other recorded case of ill health in humans from a GM food were adverse reactions to soya beans containing a brazil nut protein in people allergic to brazil nuts.

In 1993 there were 17 formal legal oppositions to GM, representing 200 groups. A year later the EU patent office awarded the GM soya bean patent to a US company, Agracetus (now owned by Monsanto of St Louis). It covered all GM plants and seeds and their natural offspring until the year 2011. It was likened to Ford being given a patent on the automobile: other companies might go on to develop another version but they would have to pay Ford a royalty for doing so.

The first crop of GM soya grown on a commercial scale was harvested in the American Midwest in 1996. The same year the EU gave permission for imports of the GM soya. The beans were not segregated,

but mixed with non-GM soya - thus making the labelling of the GM soya impossible. Monsanto argued that it was physically and economically impossible for farmers, grain companies and shippers to separate the beans.

In 1997, when the first mixed GM soya hit the UK market, the wholefood movement - led by Green City Foods of Glasgow - set up the Genetix Food Alert. Food retailers who joined were given help sourcing soya beans from other countries. Canada and Brazil are now the main sources of GM-free soya beans. Their campaign calls for a three-year moratorium on the importation, growing and use of GM foods.

l In an attempt to sort out the hopelessly inadequate UK labelling laws, the Government has proposed new safeguards which will apply to all sellers of food. Interested parties can make their comments to the Ministry of Agriculture, Food and Fisheries. Closing date is September 7.

Copies of the consultation document can be obtained from MAFF (John Furzer or Raj Pal)

Tel: 0171 238 5436

Your chance to have a say

The Herald Foodfuture Question Time, chaired by Catherine Brown, takes place on Tuesday at 7pm for 7.30pm at The Piping Centre, McPhater Street, Glasgow. A limited number of free tickets are available from The Herald on a first-come-first- served basis by ringing

0141 553 3179