Road salt—a scientific, environmental, and labour issue with a legislative solution - The Queen's Journal (queensjournal.ca)

Dropping temperatures mean students across Kingston are waking up to ice-covered sidewalks as a welcome to Canada’s natural slip ’n slide.

Along with the ice comes one white substance we can’t get enough of: road salt. Unfortunately, the use of salt not only impacts the environment, but those whose job it is to spread it.

“The salt issue is multifaceted. It’s people’s behavior and expectations. It’s how we’re dealing with liability and litigation. And then the ecology and toxicology part,” said Shelley Arnott, Queen’s biology professor, in an interview with The Journal.

Canada uses five million tons of road salt every year in an effort to save lives and avoid injuries caused by hazardous winter conditions. At Queen’s, road salt is often spread over stairs, walkways, and parking lots, keeping people from slipping while damaging the aquatic ecosystem closest to us, Lake Ontario.

Arnott remembers when people used to say, “the solution to pollution is dilution.” The idea was that society didn’t need a solution to road salt pollution, because it would wash into large water ways, diluted and safe. As a long-time researcher of the impact of salt on aquatic ecosystems, Arnott can confirm this isn’t the case.

“It was just mounting evidence that sodium chloride, or road salt, was way more toxic than we thought,” Arnott said.

Researchers like Arnott use chloride, an ion formed when salts are dissolved in water, to measure the salt concentrations in lakes near urban areas.  When Arnott began her research, she focused on its impact on smaller organisms, such as Daphnia—water fleas that feast on algae and are an integral part of lake ecosystems.

“We were seeing effects, reduced reproduction and increased mortality, at concentrations as low as five to 40 milligrams of chloride per litre,” Arnott said. “That was pretty shocking because our water quality guidelines suggest that 120 milligrams of chloride per litre should be protecting most aquatic species.”

Daphnia are highly sensitive to chloride, making them an important indicator of salt concentration in lakes. As Daphnia die, the algae they feed on will bloom and fish can perish without water fleas as a food source.

Though Lake Ontario is one of the largest bodies of water in North America, Queen’s and Kingston’s  habitual use of road salt will still have an impact, especially on organisms that live near the shore, according to Arnott.

As a long-time member of the Queen’s community, Arnott is disheartened when road salt is overused around campus. Limiting the use of salt is one way to reduce its environmental impact.

Unfortunately, oversalting isn’t a one-dimensional issue. 

Snow and ice management contractors are pressured to oversalt roads, sidewalks, and parking lots so the businesses and municipalities they work for won’t be sued.

Landscape Ontario, a horticultural trades association, has been calling for the legal protection of contractors who spread road salt within communities. The association’s Snow and Ice Management Sector group is working to reduce salt’s environmental impact.  

Aside from the environmental threat, the current legal landscape puts snow and ice contractors at a disadvantage.

The high risk of slip and fall claims increases insurance costs related to ice management. As a result, contractors are slowly abandoning businesses, according to Landscape Ontario. This is leaving municipalities without people willing to spread salt. 

“Snow and ice management contractors are essential, frontline workers. Without them, it’s impossible for Ontarians to get to work and school—and even more critically, they allow emergency services teams to reach people in need,” said Joe Salemi, executive director of Landscape Ontario, in a statement to The Journal.

As changing weather patterns cause unpredictable freeze and thaw cycles, Landscape Ontario says oversalting is becoming more common. 

“If the workers feel like they could get sued, then they’re going to put as much as they can to ensure they don’t,” Arnott said. 

A lobby day at Queen’s Park on Oct. 24 brought together ice management contractors and MPPs, as well as Doug Ford, to discuss the environmental and labor issues of road salt use in Ontario. 

Landscape Ontario hopes the provincial government will reform the liability surrounding slip and fall claims, and establish a regulatory framework for ice management to help prevent oversalting.

“We were introduced in the House by MPP Parm Gill, minister of red tape reduction, and Andrea Khanjin, minister of the environment, conservation, and parks, [who are] committed to championing the cause in [provincial legislature],” Salemi said.

Though it may be a long way from legal changes of contractor liability, there are some easier solutions.

Instead of salting the roads, some municipalities in Canada such as Kingston are using brine—a mixture of salt and water that uses less salt.

Road salt only works when there’s a little bit of liquid water on the ground already—without water, the salt has no effect. The salt ions dissociate in surface water, lowering its freezing temperature and preventing the lattice structure of ice from forming on pavement. Using brine guarantees there’s water available for the salt to dissociate, ensuring ice doesn’t form.

“It’s not taking away the toxicity it’s just reducing how much you’re using,” Arnott said.

Though there are many eco-alternatives available, Arnott cautions against believing everything on a label. 

“I can’t use salt when I know how damaging it is. So, I get out and shovel,” Arnott said.