Unapproved GM release inflames debate

The smouldering controversy over genetically modified (GM) crops has flared up again after Syngenta confirmed it had been mistakenly distributing an unapproved version of its GM maize in the US for four years.

In the UK, GM crops took a further battering with the publication of a study showing that some GM oilseed rape plants could damage wildlife, and the announcement by the Conservative Party that if it won the next election it would ban the commercial growing of GM crops.

Syngenta uncovered its mistake at the end of last year during advanced testing, when it realised that some of its GM insect-resistant maize contained the unapproved variety Bt10 rather than the approved Bt11. The company immediately informed US food and environmental regulators. The US Department of Agriculture concluded there were no safety concerns, but fined Syngenta $375,000 (198 000) and is insisting the company sponsor a compliance training conference.

Both Bt10 and Bt11 contain a gene derived from the soil bacterium Bacillus thuringiensis (Bt), which codes for a toxin that is lethal to a variety of insects but harmless to mammals. Initially, Syngenta maintained there was little genetic difference, but subsequently admitted that Bt10 also contains a gene conferring resistance to the antibiotic ampicillin. Such genes were added to GM crops to allow researchers to identify plants that had been successfully modified, but have now been removed from commercial GM crops over fears they might promote antibiotic-resistance in bacteria.

The presence of this antibiotic-resistance gene raised no additional safety or environmental concerns because it cannot express its protein in maize plants, a company spokesman told Chemistry World.

Syngenta claims the unapproved GM maize was primarily used for pre-commercial development and was only planted on around 15 000 hectares between 2001 and 2004, representing 0.01 per cent of all maize planted in the US over that period. The company also said that all current plantings and seed stock containing the unapproved variety have now been identified and either destroyed or contained.

Despite the general lack of safety concerns, this accidental release will probably act to delay further the commercial planting of GM crops in the UK, which was not due to begin until 2008 at the earliest. Additional concerns have also been raised by the publication of results from the last stage of the government's four-year farm scale evaluations, which studied the effects on wildlife of four GM herbicide-tolerant crops.

Results from the first stages, which assessed GM versions of spring-sown oilseed rape, beet and maize, were published in October 2003. Those data showed the cultivation of GM beet and rape could be detrimental to wildlife compared with conventional crop varieties. Conversely, cultivating GM maize was beneficial.

The results recently published relate to winter-sown oilseed rape and showed that growing the GM variety resulted in lower numbers of broad-leaved weeds. Flowers and seeds produced by these weeds are an important source of food for many insects and birds and researchers found fewer bees and butterflies in the GM crop.

The results from this last stage will now be passed to the UK government's Advisory Committee on Releases to the Environment to consider their implications for the future commercial cultivation of herbicide-tolerant GM crops.

Jon Evans