Two things rocked the sometimes hysterical debate on GM foods during 1999 and sent reverberations throughout the worlds of food and science. The first was the persistence of the claims by Dr Arpad Pusztai that GM foods could damage the immune system in mammals.
The second was a report by scientists at Cornell University that the monarch, the most distinctive of American butterflies, could be killed by Bt corn, which is genetically altered to produce a natural toxin (known as Bt) that acts as an in-built insecticide and is effective at keeping corn borer moth larvae at bay.
The first research was all but discredited by most scientific opinion. But the monarch study was different. It was published in Nature, one of the world's most reputable scientific journals, and triggered a PR crisis for the biotechnology industry (already suffering from European opposition) in a country which had been almost totally accepting of gene technology. As one US government official told The Irish Times: "This was the nearest thing to a dead body."
The research undoubtedly hardened EU opinion - within days the European Commission postponed a decision on a GMO release application - and caused more than a little surprise within the US administration. Taken with other reports of GM pollen travelling greater distances than anticipated, it even prompted a rethink on GM field trial conditions among US regulators.
The work of Cornell University entomologist, Dr John Losey, caused the storm. He found that if milkweed, the only plant that monarch caterpillars eat, is dusted with pollen from GM corn, which accounts for a third of US corn acreage, some of them die.
There was criticism of the way the laboratory study was done, concentrated within biotech circles. In its wake, biotechnology and pesticides interests commissioned a series of studies to quantify the risk. At a meeting in Chicago this month, early results were revealed by scientists, many of whom were funded by the industry group. Stanford University's Dr Stuart Weiss, an ecological modelling expert, told the meeting: "One thing that came out pretty clearly today is that the worst-case image that may have gotten out there of a toxic cloud of pollen engulfing the corn belt and wiping out all the (butterflies) is clearly not the case."
Much research focuses on measuring how much Bt pollen it takes to kill the caterpillars and how much might land on milkweed leaves. Prof Mark Sears of the University of Guelph concluded 90 per cent of the pollen landed within 16 feet of the GM corn field. Crop plants had an average of 78 grains of Bt pollen per square centimetre. Milkweed just three feet outside the cornfield had the equivalent of only 26 grains. It took between 500 to 700 pollen grains per square centimetre before the smallest monarch larvae began to die.
Dr Galen Dively of the University of Maryland said his work indicated the milkweed "isn't real good at catching pollen".
DR LOSEY said his latest research suggested monarchs might avoid milkweed near corn plants anyway but, significantly, he said the question remained whether Bt corn kills monarchs. "It is too early to be reassured or more alarmed based on the early data. It's too early to rule how big a risk there is going to be," he told the Chicago Tribune.
While it was claimed that many questions relating to the complex interaction between the species remains, and some believed so much GM corn should not have been planted because of doubts, its pollen "poses an insignificant threat to the monarch", entomologist Dr John Foster of the University of Nebraska concluded. This was especially so when compared to damage caused by mowing of milkweedrich meadows and rights of way in the US and habitat destruction in Mexico.
Asked if the industry's funding of his research might bias his views, the Washington Post reported his reply: "They don't give me enough money to buy my opinions."
kosullivan@irish-times.ie