Unfortunately , I can't find statistics for Canada, but in the U.S. Firefighters do not even make the list of the Top Ten most dangerous jobs , link;
https://careers.financesonline.com/t...y-career-path/
You mention cancer constantly related to firefighting,
smoking cigarettes gives you cancer, [do you smoke ?]friend of ours died of lung cancer due to sprays used in their apple orchard [ because consumers want blemish free nice looking apples] I ate many apples with maggots, because my father did not spray , we ate strawberrys , cherries, plums, currents, goose berries, raspberries right off the plants, it didn't harm any of us because as I said dad did not spray [very few sprays were available in those days].
Cancers of different types somehow develop in people that are not connected in any way in firefighting, so that arguement you can throw out wherever it pleases you
The food we eat, a necessity for survival [living], that I/we buy should not contain dangerous chemicals that accumulate in our bodies to cause allergies and illness [ just for the sake of the all mighty dollar in MR. Big Chemicals Pocket ]