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Friday, 22 October, 1999, 13:40 GMT 14:40 UK
Health risks reduced by GM corn
Fusarium ear rot is extremely common (Photo: Munkvold)
There is evidence to suggest that some genetically modified (GM) crops now being grown commercially in the US can have distinct health advantages, according to plant disease experts.

Corn which has been engineered to make it resistant to insects also has lower levels of mycotoxins, which are potentially dangerous to humans and animals and are produced by the fungi that cause plant diseases.

Insects can exacerbate the problems. When larvae chew on stalks and kernels, they create wounds where fungal spores can enter the plant. Once established, these fungi often produce mycotoxins. Some of these, such as fumonisin, can be fatal to horses and pigs, and are probable human carcinogens.

Bt-corn has become very popular with American farmers. It has been modified to incorporate a gene from the bacterium Bacillus thuringiensis (Bt). This makes the plant tissue toxic to the European corn borer, a significant pest that hides in the stalks of the plant, making it difficult to control with chemical sprays.

Dr Gary Munkvold, a plant pathologist at Iowa State University, says that some of the add-on benefits of GM crops should not be overlooked in the on-going debate about their safety.

'Benefit to consumers'

"Lower mycotoxin concentrations in Bt-corn hybrids clearly represent a benefit to consumers," he says. "Studies show Bt-corn hybrids that control European corn borer damage to kernels usually have very little Fusarium ear rot, and consequently, lower fumonisin concentrations."

Dr Munkvold details some of the toxins that can build up in corn in an article he has written for the American Phytopathological Society (APS).

He says kernel rot caused by the fungus Aspergillus is associated with insect damage to corn ears, and this can lead to the most notorious mycotoxins found in corn, the aflatoxins.

"The economic impact of aflatoxins has been greater than that of other mycotoxins in corn because aflatoxins can be passed into milk if dairy cows consume contaminated grain," says Dr Munkvold.

Bt-corn was at the centre of the GM controversy in May when scientists from Cornell University, US, showed that pollen from the crop could kill the larvae of Monarch butterflies. Their research, published in the journal Nature, was a demonstration of how the new GM technology might have unwanted consequences for biodiversity.

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20 May 99 | Sci/Tech
GM pollen 'can kill butterflies'
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