WINNIPEG, Manitoba — Canadian consumer groups, scientists, and farmers joined forces Tuesday to demand that the federal government postpone approval of genetically modified wheat, saying the engineered crop could devastate wheat exports and harm human health.

"This is an inadequately tested experiment that has no place contaminating our farms and food," Holly Penfound, a member of Greenpeace Canada, told a news conference. "Our government should be calling the shots, not the big biotech companies pushing GM wheat into the market," said Penfound who is Greenpeace's environmental health coordinator.

The coalition of environmental groups, consumer watchdogs, and grain marketers sent a letter to Prime Minister Jean Chretien, asking him to put the brakes on introducing transgenic wheat until its effects on the environment, consumer health and agricultural trade are addressed.

The groups were reacting to plans by U.S.-based biotech company Monsanto to introduce the world's first genetically modified (GM) wheat — known as "Roundup Ready," a herbicide-tolerant, spring wheat variety — between 2003 and 2005.

This past spring, the company seeded several test fields at secret locations across the Canadian prairies, news of which heightened public suspicion.

Monsanto and other biotech firms working on transgenic wheat argue that their genetic engineering will boost production and reduce the need for farm chemicals. (Monsanto's crops are designed to resist its Roundup Ready weedkiller, allowing farmers to destroy weeds without damaging plants.) But critics say that GM crops could cross-pollinate and pollute non-GM fields.

"This is just really very powerful technology, and it's got a lot of potential, but it's misapplied in this case. It's not something farmers want," said Bill Toews, a grain farmer in Kane, Manitoba.

At a time when many of Canada's wheat customers in Europe and Asia are demanding GM-free certification, the Canadian grain industry is especially nervous about the ability and cost of segregating GM and non-GM crops.

Canada is one of the largest wheat producers and exporters in the world, shipping about 12 million tons worth between C$3 billion and C$5 billion (US$1.96 billion and US$3.27 billion) annually.

Patty Rosher, market development program manager with the Canadian Wheat Board, said, "The whole world is looking at this from fresh eyes, and I think in Canada we also need to look at our variety registration system or the regulations we have in place right now for approval and think about the fact that it is new technology and we may need to make a change." The board, which controls all of Canada's wheat, durum, and barley exports, has already lobbied Ottawa to make market acceptance of GM wheat a criteria for regulatory approval.

Monsanto, which says it will also seek commercial approval of Roundup Ready wheat in the United States, has recently tried to ease public mistrust and industry unease by consulting with various groups.

"If we don't have a product that is going to provide benefit to farmers, benefit to the industry, and it's (not) going to be accepted by consumers, then essentially we don't have a product," said Trish Jordan, a spokeswoman with Monsanto Canada, based in Winnipeg. "They're saying they do not want GM wheat at this time, which is fine because we're not ready to introduce it at this time," Jordan said.

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