Some residents in Colchester County, N.S., are worried about the effects of the herbicide glyphosate being sprayed on land near waterways, and new research out of McGill University suggests there is cause for concern.
Glyphosate is used in the forestry industry to kill deciduous trees, allowing the softwoods sought by harvesters to grow unhampered.
Every year, Nova Scotia’s Environment Department issues permits to companies to spray the herbicide in forests around the province.
An area near Stewiacke, N.S., has been targeted for spraying this year, much to the ire of community members and environmental activists.
“As soon as it rains, it’s going to run into [the brook]. It’s like a spiderweb of brooks and swamps and ponds and little lakes,” Ellen Durkee, a lifelong resident of the Middle Stewiacke area, told CBC Radio’s Information Morning on Friday.
“They’re not allowed to apply it anywhere near any kind of waterway, [but] they can’t be avoided in this area.”
Durkee is among a number of residents who are opposed to spraying in the area. Protesters have set up camp near the targeted forests in hopes their presence will deter companies from spraying the herbicide.
“I’m concerned because I don’t like the idea of messing with nature. I think forests as a variety of trees are better left the way they are,” Maryanne Lohnes, who lives near Stewiacke, told Information Morning.
“I also think that the spraying of the herbicide can affect wildlife, microorganisms, waterways, people and a variety of other things.”
Two new studies out of McGill University in Montreal found glyphosate puts freshwater ecosystems at risk even when its application meets approved guidelines.
“We did this big outdoor experiment where we had 100 experimental ponds filled with natural lake water with natural bacteria, natural algae and natural water fleas,” Marie-Pier Hébert, who co-authored the studies, told CBC’s Information Morning on Thursday.
“And what we found is … glyphosate concentrations as low as 0.1 milligrams per litre could lead to a species loss of zooplankton.”
Information Morning – NS9:05New research on how glyphosate can affect freshwater ecosystems
Zooplankton are small aquatic microorganisms that live in waterways, some of which feed on potentially harmful phytoplankton like cyanobacteria.
Hébert, who is a PhD candidate in biology, said Canada’s water quality guidelines suggest a maximum concentration of 0.8 milligrams of glyphosate per litre over long periods, which could easily kill zooplankton.
She said if these zooplankton are killed off by glyphosate being washed into freshwater ponds and wetlands, it could upset the ecosystems and alter the aquatic food web.
“For instance, if those species were fulfilling some functions in the ecosystem, these functions will be lost,” Hébert said.
“If those zooplankton organisms were grazing on algae, they were controlling algal blooms, or if they were the preferred food of fish predators, then those fish won’t have as much food as they used to if the zooplankton died because of the presence of glyphosate.”
Hébert said it is possible — although not proven — that the loss of certain zooplankton may have contributed to an increase in blue-green algae blooms in Nova Scotia.
Blue-green algae, also known as cyanobacteria, can be toxic to humans and animals. The blooms have become more common in Nova Scotia in recent years.
“Many studies have found a natural resistance of cyanobacteria and blue-green algae to glyphosate in the sense that they’re not affected by the presence of glyphosate, and they can actually use glyphosate as a resource to proliferate,” she said.
“So that could be one of the potential consequences of glyphosate if the glyphosate ends up in the water and kills other organisms.”
Glyphosate is approved by Health Canada, which has said it does not consider the chemical to be a risk to humans or animals if it’s used correctly.
“Our No. 1 priority is to protect the health and safety of Canadians and the environment,” Mark Johnson, a spokesperson for Health Canada, said in an emailed statement.
“Before a pesticide is allowed to be used or sold, it must undergo a rigorous scientific assessment process that provides reasonable certainty that no harm, including chronic effects such as cancer, will occur when pesticides are used according to label directions.”
Johnson said up to 200 scientific studies were considered when glyphosate was last evaluated for forestry use in 2017.
Despite this, Hébert said this new research should be considered in the next evaluation since it was tested in natural outdoor spaces, rather than in a lab.
“This is something to keep in mind that perhaps some studies that are conducted outside under natural conditions with natural populations should be more present in this type of report,” she said.