The drive west along the 401 into Mississauga is lined with factories, box stores, furniture outlets and timber suppliers. It’s an industrial area, but also a commuters’ hub, where people from across the Greater Toronto Area come to gather at mosques, temples and weddings in splashed-out convention centres.

Residents seem unaware of a facility in an inconspicuous office building at the intersection of Ambassador Drive and Kennedy Road South, one that uses an invisible and odourless carcinogenic gas.

The plant is owned by Sterigenics, which sterilizes medical supplies, like respirators, using ethylene oxide — an effective sterilant of heat-sensitive devices used by many of North America’s doctors, hospitals and health centres. Ethylene oxide emissions are toxic to humans when high amounts are breathed in and the chemical has been considered to have “a probability of harm at any level of exposure” by Environment Canada and Health Canada since 1999. (PDF link)

Sotera Health, the Ohio-based company that owns Sterigenics, has been named in a series of American lawsuits brought by claimants who say they developed illnesses, particularly cancers including leukemia, myeloma, lymphoma and breast cancer, because of ethylene oxide exposure. In 2023, the company agreed to settle a class-action lawsuit in Illinois, paying claimants US$408 million. It’s also paying out US$35 million in Georgia. In both instances, Sterigenics said the settlements should not be considered an “admission of liability.” A New Mexico case is pending.