BioWorld International Correspondent

LONDON - There is no evidence that eating genetically modified crops and produce currently on the market poses any threat to human health, but more research is needed on potential environmental impacts, according to a scientific review of the safety of GM crops carried out on behalf of the UK government.

"Worldwide, there have been no verifiable ill effects reported from the extensive consumption of products from GM crops over seven years by humans and livestock," says the review, which was carried out by a 24-member panel, led by the government's chief scientist, David King. In total, the review considered 600 scientific papers and examined 17 topics relating to the subject, many of which were highlighted as causes of concern by the general public.

Overall, the 300-page report is broadly in favor of existing GM crops, but it does not give complete approval, pointing out that, as GM is not a single technology, its applications should be considered on a case-by-case basis.

King said, "GM is not a homogeneous technology on which scientists can make blanket assurances on safety."

The most serious issue is the potential effect of GM crops on farmland and wildlife, where there are gaps in knowledge. Those uncertainties will increase as the range of GM plants and introduced traits increases. Of most concern is the issue of whether extra herbicides applied to herbicide-resistant crops would lead to a long-term reduction in weed populations and the wildlife that depends on those weeds for food. This issue is being investigated as part of current field trials of herbicide-tolerant crops.

More research is also needed in areas including allergenicity, soil ecology, farmland biodiversity, and the consequences of gene flow to weed relatives.

Notwithstanding these gaps, the report says, "Detailed field experiments on current-generation GM crops show that in a range of environments they are very unlikely to invade the countryside and become problematic plants. Nor are they likely to be toxic to wildlife."

Depending on the crops developed, GM may present greater challenges in risk management in the future. As a result, the report says, "It is important to continue to develop safety assessment technologies, effective surveillance, monitoring and labeling systems." GM regulations also need to keep pace with new developments.

The review panel consisted of scientists and non-scientists who are known to represent a range of views from pro- to anti-GM.

In many respects the review reflects the way public opinion is polarized, with those who are pro-GM claiming the absence of harmful effects to date means GM should be given a clean bill of health, while those who are opposed to the introduction of the technology argue that further research is needed to ensure safety.

So, for example, the report says, "To date worldwide there have been no verifiable untoward toxic or nutritionally deleterious effects resulting from the cultivation and consumption of products from GM crops." But it then goes on to say, "Absence of readily observable adverse effects does not mean that these can be completely ruled out."

No wonder then that King was forced to conclude, "We cannot know everything and if we are paralyzed by gaps in knowledge we would never get anywhere new."

The GM science review follows the publication earlier this month of a government-sponsored study of the cost benefits of growing GM crops in the UK, which concluded weak consumer demand means the current generation of GM crops is of little economic value to the UK.

A third investigation into GM issues, in the form of national public debate, will report its findings in September. The results of field-scale trials also are due to be published in September, and all the findings will be considered by the government in advance of an EU decision later this year on whether or not to lift the current ban on licensing GM crops.