Not long ago, glyphosate was touted as a “once in a century” herbicide. It was said that the chemical — introduced in 1974 and better known by its brand name, Roundup — could do something that its predecessors, such as DDT, could not: get rid of weeds without negatively affecting people's health or the environment.
But ever since the World Health Organization's International Agency for Research on Cancer declared the chemical possibly carcinogenic in 2015, glyphosate has come under closer scrutiny. Many European countries have responded by introducing bans or other legislation to limit its use. In Canada, however, the chemical is a legal and popular — as well as inexpensive — form of weed control. Worldwide, it sells more than the next 10 most popular competing products combined, in terms of value and amount, according to Francois Tardif, a plant-agriculture professor at the University of Guelph who specializes in weed resistance.
But glyphosate’s critics say that, although the toxicity of the molecule might be lower than what’s found in other products, the herbicide’s widespread use in high volumes creates health and environmental risks.
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TVO.org looks at how glyphosate is used in two different Ontario industries — agriculture and forestry — and the pros and cons of existing alternatives.
Glyphosate in agriculture
As many farmers did in the 1990s, Blake Vince began relying more on the herbicide to control weeds after glyphosate-resistant, genetically engineered corn crops had been introduced and glyphosate prices had dropped as the original patents on it expired. Previously, he and other farmers had used the chemical sparingly — often as a spot spray — to treat hard-to-get-rid-of weeds as a crop grew, or before planting or after harvest so it wouldn't kill crops. But Vince, who farms 1,200 acres west of Chatham, was able to use glyphosate throughout the growing season on genetically modified varieties of corn (and, later, soybean seeds).
“It is a whole system,” he says. “They sell you the seed with the traits that allow you to use the chemical to ensure you have an immaculate field free of anything other than the intended crop to harvest.”
Glyphosate-resistant seed might have cost more than the non-engineered alternatives when it was introduced — and still does — but it slashed farmers’ weed-control budgets from $50 an acre to $10 to $15, says Tardif. By the early 2000s, however, weeds that were resistant to glyphosate were appearing stateside and, in 2008, resistance was confirmed in giant ragweed near Windsor. Today, in Ontario, four species of weeds, some of which are widespread across the province, have glyphosate resistance, Tardif says: "That's when it really struck home for farmers here."
For Louise Hénault-Ethier, the David Suzuki Foundation’s science-projects manager in Quebec and Atlantic provinces, the concern is that farmers will respond with more chemicals to tackle more resilient weeds. “I fear from a scientific standpoint that it will increase pesticide usage in the long term,” she says. “It’s so easy to rely on spraying something over a whole field that people don’t necessarily know how to take advantage” of other strategies.
However, methods that limit or eliminate herbicide use in agriculture are evolving. Some farmers use equipment that employs cameras that, using artificial-intelligence technology, activate a nozzle to spray herbicide if weeds are encountered. Selective flamers, which direct flames to weeds, are another approach. And using drones to spot and treat weeds also looks promising, Hénault-Ethier says. Other technologies under development combine robotics and AI to detect weeds and either spray them or pull them out, says Tardif: “It sounds like science fiction, but a lot of teams are working on that.”
Many solutions involve farmers rethinking how they manage their fields, such as by planting tightly packed crops to crowd out weeds. "Glyphosate was the giant hammer that will kill the weed; now we're trying to replace that with a bunch of little hammers that, combined together, would get the same effect," Tardif explains. "The problem is that these tend to be more unpredictable, and sometimes we don't know what are the best combinations."
Since 2013 on the Vince farm, the primary strategies to reduce glyphosate use have included abandoning genetically modified seed and adding cover crops — plants such as rye, crimson clover, hairy vetch, and peas grown not for sale but rather as barriers between for-market crops. The idea, Vince explains, is that cover crops reduce the growth of weeds by cutting off sunlight or releasing natural chemicals that can suppress — and even kill — unwanted plant growth. “I’m less than a litre per acre per year,” he says of his farm’s current glyphosate use (he once used three litres per acre).
Hénault-Ethier wants to see Canada adopt national regulations similar to those of the European Union, which require farmers to use integrated pest management — a system through which farmers must look at other solutions before introducing pesticides. “It’s good practice to seek alternatives to pesticides,” she says. Asked whether Health Canada has considered mandating integrated pest management, a spokesperson for the department says it is included in the National Standard for Pesticide Education, Training and Certification in Canada. “Certification and training of pesticide applicators is done by provincial regulators based on the National Standard,” the spokesperson says. “Farmer training and certification requirements may vary across provinces depending on the class of pesticide being used.
”In Ontario, the Ministry of the Environment, Conservation and Parks supports integrated pest management. "Ontario promotes the use of Integrated Pest Management (IPM) principles for the management of pests in agriculture," a ministry spokesperson says by email. "Farmers need to be trained through Ontario’s Grower Pesticide Safety Course before they can buy commercial pesticides, including glyphosate, for use on their farm," the spokesperson adds, noting that the safety training includes the management approach and provides related resources. But Hénault-Ethier says the solution must be binding and federal, as the Canadian government registers the pesticides that farmers are allowed to use. Provinces and municipalities can have more stringent regulations, and many do, but this approach is inconsistent and inefficient compared to one authority setting the rules, she says: “It’s not uniform.”
Glyphosate in forestry
In forestry, glyphosate is used to make room to grow desired trees by killing competing vegetation. According to the Ministry of Natural Resources and Forestry, “Herbicides are only used when necessary to renew the forest,” and they’re applied on about 0.2 per cent — or 1,120 square kilometres — of Ontario’s 560,000 square kilometres of Crown forests.
In a natural setting, Natural Resources Canada research scientist and eco-toxicologist Chris Edge says, regrowth areas play an important role in an ecosystem. But in a forest-management unit — a designated area licensed to a forestry company — the ultimate goal is to regrow a certain tree on particular site. Having studied glyphosate’s direct impact on wildlife, Edge says, “We can detect glyphosate in new vegetation — after application, we can detect it for a year. But after about 18 days, the concentrations are so low that they're below any sort of threshold set by Health Canada.”
Chief Marcus Hardy, of Red Rock First Nation, which co-owns Lake Nipigon Forestry Management with Animbiigoo Zaagi'igan Anishinaabek and Biinjitiwaabik Zaaging Anishinaabek First Nations, says the communities strongly oppose the use of glyphosate, particularly via its common application — aerial spraying — within the Nipigon forest. “There are a few elders that were adamant on explaining exactly what their concerns were,” he says, adding, “we saw less growth in the bush; we saw less plants, medicine plants, blueberries and all that.” Regional organizations such as Nishnawbe Aski Nation, which represents 49 First Nations in Ontario; Mushkegowuk Council; the North Shore Tribal Council; and individual band councils within these organizations have also released resolutions opposing its use. Hardy says the community relies on the forest as part of their food supply. “Our people use the bush for their grocery store,” he says. Instead of aerial spraying, the forestry management company spot sprays glyphosate so that it can use less and be more precise in its application.
Despite the lack of direct adverse impacts on species, Edge acknowledges that the principles of sustainable forestry take other factors — such as social acceptance and broader ecological impacts — into consideration. “Crown lands are a public resource,” he says. “If people don't want their forests managed that way, then that should definitely be taken into account.” A Ministry of Natural Resources and Forestry spokesperson tells TVO.org in an email that “public input on sustainable forestry regulations and policies are sought and considered when elements of the policy framework are revised or new pieces added, including those related to the use of herbicides.” However, the province notes that the Pest Management Regulatory Agency “has determined glyphosate does not present unacceptable risks to human health or the environment when used as directed.”
Jurisdictions such as Quebec have banned the application of herbicides in forestry, and
MP Jenica Atwin has proposed a private member’s bill aimed at banning glyphosate nationally. Fellow NRC researcher Nelson Thiffault says that Quebec’s legislation has led to the use of alternative methods, including replanting more mature seedlings — which are stronger and more capable of beating out competing plants — and hiring crews to manually remove competing plants within the regrowth areas. However, he says, these alternatives cost more; while aerial spraying costs $200-300 per 10,000 metres squared, the costs of the alternatives are roughly $500-600 per 10,000 square metre (although that can increase depending on site conditions). In Quebec, these costs are offset by the province, which contracts the seedling operations and pays the crews on public lands, according to Thiffault. Costs in Ontario would typically fall on the forestry company, according to MNRF.
Hardy says that, because MRNF is a licensed forester, the communities can take ownership of how their forest is managed: “It’s great financially, but the most important thing is the longevity of the forest. We're stewards of the land, and we need to take care of it. We need to make sure that things are done right — safely.”
What's next for glyphosate?
Environmental groups are calling for the Pesticide Management Regulatory Agency, the Health Canada branch that regulates pesticides, to reconsider its 2017 decision to renew glyphosate’s approval for use in Canada without new restrictions. (The chemical is next scheduled for review in 2032, although Health Canada has pledged to monitor for new information about the chemical and take action if necessary.) In March 2020, Canadian non-profit Safe Food Matters launched an appeal of an earlier Federal Court judgment that upheld Health Canada’s decision. A spokesperson for EcoJustice, which, as an intervenor in the case will argue alongside Safe Food Matters, says by email that no date has yet been set for the hearing.
A Health Canada spokesperson notes by email that the 2017 review took into account 1,300 studies that totalled more than 89,000 pages. "This science based review indicated that potential risk to human health and the environment is acceptable when the label directions" are followed, the spokesperson writes. "It would be inappropriate," the spokesperson says, "to comment on the specifics of this case while it is before the court."
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