Canada Seeks Tougher Grain Dust Limit, Weaker Flour Protections

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By Peter Menyasz

Canada has proposed stricter limits on occupational exposure to grain dust to protect workers, but weaker limits for exposure to flour dust to ease compliance for employers.

The changes are intended to ensure maximum protection for federally-regulated workers, while ensuring employers can meet the requirements, and the stricter limit for grain dust would harmonize federal standards with Canada’s provinces, Employment and Social Development Canada said June 10.

The proposed changes would amend the Canada’s occupational and maritime safety regulations, covering about 900,000 workers primarily in the grain movement, banking, transportation, and telecommunications sectors. The changes would take effect after publication in the Canada Gazette, Part II, and affect about 350 grain handling facilities and about 50 wheat flour mills.

Proposed amendments would set a maximum occupational exposure limit (OEL) for grain dust at 4 milligrams per cubic meter, less than half the current limit of 10 mg/m3, the government said.

“The current OEL for grain dust is too high and therefore puts the health and safety of federally regulated workers at risk,” the department said in a notice in the June 10 Canada Gazette, Part I. “Both employer and employee representatives agree that the current OEL for grain dust is not appropriate.”

The amendments would also increase the OEL for flour dust to 3 mg/m3 from 0.5 mg/m3. The current limit is impracticable, requiring workers to wear respiratory protective equipment at all times and interfering with performance, it said. A less stringent limit would fall in line with provincial standards and provide flour mill workers with “technically feasible” protection.

The draft regulations are open to public comment through July 10.

Exposure Limits Would Match Global Rules

The more stringent exposure limit for grain dust is based on scientific studies showing that exposure to elevated concentrations can cause health effects including bronchitis, upper respiratory tract irritation, asthma, and decreased lung function, the department said.

The American Conference of Governmental Industrial Hygienists adopted the 4 mg/m3 standard for grain dust in 1985, in part based on work by Canadian researchers. The recommendation was adopted by provincial health and safety jurisdictions more than 20 years ago.

Australia, England,and Japan have each adopted the 4 mg/m3 standard, but the U.S. Occupational Safety and Health Administration still uses a 10 mg/m3 standard.

Consultations to date found support from employee representatives for the 4 mg/m3 limit, but employer groups, while admitting that the current limit isn’t stringent enough, have questioned whether there is sufficient evidence to support the tougher standard, the department said.

Canada’s provinces currently have a range of exposure limits for flour dust, but the U.S., a direct competitor to the Canadian flour milling industry, doesn’t currently have a specific occupational exposure limit for flour dust, the department said.

Employee representatives fully support the proposed 3 mg/m3 limit for flour dust, but employers continue to argue that even with engineering controls, the proposed level would not be achievable without employees wearing personal protective equipment for some activities, the department said.

To contact the reporter on this story: Peter Menyasz in Ottawa at

To contact the editor responsible for this story: Rachael Daigle at

For More Information

The proposed regulations are available at

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