Transport Canada was concerned about forever chemicals, known as per- and polyfluoroalkyl substances (PFAS), as far back as the 1980s, files obtained through an access-to-information request confirm.

Thousands of chemicals fall within the PFAS family, and some have been linked to liver and prostate cancer, pregnancy-induced hypertension, fatty liver disease and to affecting lipid function, which is linked to Type 2 diabetes.

For decades, Transport Canada — along with the Department of National Defence (DND) and the National Research Council of Canada — conducted firefighter training exercises at airports across Canada with aqueous film-forming foams that contain PFAS.

The foams were seen as an effective way to fight jet fuel fires, but their use at sites across the country contaminated groundwater with the forever chemicals.