Cape Town — Traces of genetically modified organisms can be found in nearly three-quarters of locally sold maize and soya products that claim to be free of these ingredients, researchers at the University of the Free State have found.

This meant that thousands of consumers who buy products labelled "genetically modified organism-free", "nongenetically modified" or "organic" may be eating food containing gene-altered ingredients, said Chris Viljoen, director of the university's genetically modified organism testing facility.

Food producers and retailers were not deliberately misleading consumers, he said, as there were currently no guidelines or standards defining these terms in SA.

SA is the only African country that grows genetically modified crops on a commercial scale. An estimated 24% of yellow maize, 10% of white maize, 50% of soya and 85% of the cotton production in 2004 was genetically modified, according to the International Service for the Acquisition of Agri-Biotech Applications, a global industry body that promotes genetically modified technology in developing countries.

Viljoen and his colleagues randomly selected 58 maize and soya products from supermarket shelves, and tested them for gene-altered components.

The results, published in the latest edition of the African Journal of Biotechnology, show 44 (70%) of the food products contained genetically modified ingredients. Fourteen of the 20 products labelled genetically modified organism-free, nongenetically modified or organic tested positive for genetically modified organisms. These included products as diverse as soy milk powder, "vegi" steaks, cornflakes, maize meal and self-raising flour.

The findings highlighted the need for effective regulations to protect consumers against misleading claims, said Viljoen.

"There is no regulatory body controlling labels, so how much of it is accurate? Inaccurate labelling is not illegal, but it has implications for consumers," he said.

South African law currently does not require food producers to label goods containing genetically modified components.

Different countries used various standards, complicating matters still further for consumers who purchased imported foodstuffs, said Viljoen. For example, some countries considered "genetically modified organism-free" to mean zero genetically modified, while others applied this term to foods with less than a specific threshold.

In the European Union, "organic" implied zero genetically modified organisms, while the US agriculture department allowed a 5% threshold for "organic", he said.

Pick 'n Pay deputy chairman David Robins said the retail group believed government should introduce mandatory labelling of food containing genetically modified ingredients.

"We don't have a position on whether it's good or not, but people should know what they are buying" the deputy chairman said.

Robins said the retailer did not stock products claiming to be free of genetically modified organisms as the firm did not have confidence in the truth of these assertions

Woolworths said it had decided in 1999 to remove or replace ingredients from genetically modified crops wherever possible, or to label affected products.

Since 2002 it has labelled all products that might contain ingredients derived from genetically modified crops.