Cancer conference explores risks from pesticides

Does eating foods produced with agricultural pesticides give people cancer?

That was one of the questions on surgical oncologist Carman Giacomantonio’s mind when he travelled from Nova Scotia last week to attend the Canadian Cancer Society (CCS) conference titled Exploring the Link Between Pesticides and Cancer.

Giacomantonio, who also sits on the cancer society’s board, said he is often confronted with patients who wonder whether it is residues on the food they ate that resulted in their cancer.

“I’ve always said, well, ‘perhaps.’ But I’m a little more confident now in saying ‘probably not,’” Giacomantonio said as the two-day conference drew to a close. “Some of the myths I carried have been dispelled.”

“What we saw yesterday from the data, there is essentially no clear association between pesticides, the herbicides we use

“We’ve become a society living longer, living healthier and far more affluent and it is probably the very things that we are questioning today that got us where we are.”

– Carman Giacomantonio

and the cancers – there are too many other confounding factors,” said Giacomantonio.

He still sees reason for caution and stringent monitoring. But he said he’s now more confident Canada’s pesticide regulatory system does a good job protecting the public from harmful chemicals.

“We’ve become a society living longer, living healthier and far more affluently, and it is probably the very things that we are questioning today that got us where we are.”

Evidence lacking

His assessment aptly summarized the state of the science when it comes to cancer and pesticides.

There were red flags, some troubling correlations, and gaps in the research protocols identified by the internationally recognized researchers presenting to the conference. (See related story page 23.) But no smoking gun.

“I think most of them aren’t carcinogens, but I’ll bet some of them are,” said Aaron Blair of the U. S. National Cancer Institute. “The challenge is finding which is which.”

Blair said it is important to remember that pesticides are unique among chemicals. “They are designed to harm a living system and I think it’s different; there are some reasons I think we ought to be worried.”

Blair said while this conference focused only on cancer, some pesticides are known to cause other ill effects such as neuro-and immuno-toxicity.

Residue free

But there was also data presented that showed 99 per cent of the foods Canadians eat are within the maximum residue limits set by Health Canada. And those limits are set 100 to 1,000 times lower than levels identified as safe in animal testing. The risks, if there are any, accrue mainly to the people working with them all the time, such as farmers.

Giacomantonio was among many of the more than 200 participants who left the Toronto conference reassured – and not solely because they can now eat without fear.

The decision by the Canadian Cancer Society to even hold such a conference was highly controversial – seen by many in the farming community as well as CropLife Canada a precursor to expanding its call for a ban on cosmetic use of pesticides to include agriculture.

CropLife president Lorne Hepworth left feeling not only reassured, but somewhat vindicated. “I think if the entire Canadian public could have heard what we heard in the last day and a half… they should feel pretty reassured about the safety of pesticides and the food that is produced from them,” he said in an interview.

“Here are some pretty exhaustive high-powered folks and the message there was pretty much there was no risks here that could be identified to any extent.”


The conference publicly aired the dilemma haunting the society since 2001 when it called for a ban on the cosmetic use of pesticides on the basis there was no clear health benefit from their use and the potential for harm, even though the science was inconclusive. At least 145 municipalities across Canada and three provinces – Quebec, Ontario and now Alberta – have since taken the society’s advice.

In the meantime, the society has continued to promote the consumption of fruits, vegetables and whole grains as part of a cancer prevention strategy. However, in many cases those foods are produced with the assistance of pest control products.

“We had been asked all along – what’s the difference? If it is bad for cosmetic uses, why isn’t it bad for non-cosmetic uses?” said Heather Logan, senior director, cancer control policy and information for the CCS.

Recent polls conducted by the society have shown 60 per cent of Canadians are concerned about pesticide residues in their food. Twenty-four per cent said they opt for foods that have not been exposed to chemicals when possible.

Fifty-five per cent said they didn’t feel they have enough information to make informed choices and 74 per cent said they would support stronger federal regulations to reduce pesticide use.

Logan said it was clear to society officials that using pesticides to produce food is a different issue than using them to keep lawns dandelion free. Rather than reach a decision within a cloistered environment, Logan said the society decided both it and the public need to better understand the complexities.

Affordable food

“Ultimately what it comes down to is a very different risk/benefit profile,” Logan said. “There may be some benefits. It helps us produce a higher quality and higher quantity of fruits and vegetables and keep them affordable. That’s important if you don’t have the sort of income to support organic sources.”

While it is possible to move away from the use of pesticides in agriculture, it can’t happen without a huge investment to make alternative farming systems accessible and viable for mainstream farmers, said Rene Van Acker, chair of the plant science department at the University of Guelph. “To suggest we can go wholesale organic by default, I think is not possible,” he said. “We have to be realistic.”

But he said there are many areas where farmers can and do build robust farming systems that require fewer or no pesticides through integrated pest management strategies.

Logan said she’s pleased the conference laid the industry’s fears to rest.

“I am glad to hear they are reassured because we tried to tell them that beforehand and tell them we’re here objectively… but I think they had to hear that for themselves,” she said.

Logan, who comes from a farm background, said the conference identified areas where more research should be done. But she said farmers need to understand the society is willing to work with the farming community as it continues to explore the issue. “They are the ones who spent their lives every day, long hours every day, in this field and they have to make sure that any recommendations or actions that come out of it are grounded. They will have a strong voice.” [email protected]

About the author

Vice-President of Content

Laura Rance

Laura Rance is vice-president of content for Glacier FarmMedia. She can be reached at [email protected]



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