Raising traceability issues, researchers from the US Environmental Protection Agency (EPA), found that cross-pollination over such a distance was much further than previously measured and is believed to be a record for any GM pollen, reports CORDIS.
In Europe, new rules recently introduced for genetically modified food ingredients and tougher labelling laws mean that food manufacturers are on the alert for Identity Preserved - easily traced - ingredients, essential to avoid the risk of contamination.
According to the New Scientists he grass in question is an experimental variety of GM creeping bentgrass, modified to make it resistant to herbicides, and has been grown in experimental fields in Oregon, US, for the past two years.
Lidia Watrud and colleagues from EPA's national health and environmental effects research laboratory in Oregon, collected seeds from wild grasses growing in an area stretching tens of kilometres in every direction from the experimental fields. They then grew the seeds in greenhouses and tested the resulting grasses for signs of contamination by the GM variety.
The team recorded significant levels of cross-pollination in samples from seeds collected within two kilometres downwind of the GM plots, but were more surprised to find contaminated seeds covering an area of 310 square kilometres, with the furthest example 21 kilometres from the GM source.
Few studies have previously investigated cross-pollination from crops - GM or traditional - at distances of more than a few hundred metres. In light of this latest data, it has been suggested that windblown pollen from certain crops could travel hundreds of kilometres from its source.
Scotts, the Ohio-based seed company that developed the GM bentgrass, collaborated on the EPA study.