Despite concerns from some critics of genetically modified crops that the foods may raise consumers’ risk of allergic reactions, a new study finds no evidence that this is the case.

The study, by researchers in Portugal, adds to evidence that several widely used strains of GM corn and soybeans do not promote food allergies.

All of the products - three corn strains engineered to resist certain crop-ravaging insects and a soybean variety that tolerates a common weed killer -have been on the market since the 1990s. The new study looked at a group of allergy-prone adults and children who had consumed products containing the biotech foods at some point since their approval in Europe.

The researchers, led by Rita Batista of Portugal’s National Health Institute in Lisbon, gave 77 study participants allergy tests to see whether they reacted differently to the GM corn and soy than they did to conventional varieties.

None of them did, according to findings published in the Journal of Allergy & Clinical Immunology.

Much of the corn and soybeans grown in the U.S. is transgenic, meaning a gene or genes has been inserted into the genome of the plants to give them a desired trait.

European countries have been much slower to embrace the technology, as consumers there are far more wary of what some call “Frankenfoods.” One of the concerns some critics have raised is the potential for allergic reactions to the foreign proteins in GM foods; if a gene were transferred from an allergenic source, that could make the resulting GM food more likely to trigger allergies.

The products tested in the current study included two manufactured by U.S. biotech giant Monsanto, a corn variety known as MON 810 that is engineered to resist certain insects, and Roundup Ready soybeans, which are designed to tolerate the company’s Roundup weed-killer.

The researchers also tested two pest-resistant corn varieties made by the Swiss firm Syngenta and one herbicide-tolerant strain manufactured by Germany’s Bayer Crop Sciences. None of these products, the study authors note, contain genes derived from sources known to trigger allergies.

Batista and her colleagues used skin prick tests to place protein extracts from the corn and soy strains under participants’ skin. They found that though adults and children with a history of sensitivity to corn and soy had skin reactions to the extracts, their reactions were the same to GM and non-GM varieties.

“The transgenic products under testing seem to be safe in terms of allergenic potential,” the researchers write. They do, however, call for routine postmarket testing to monitor the possibility of allergic reactions to GM foods.

SOURCE: Journal of Allergy & Clinical Immunology, August 2005.