Fair enough.
You say one 'large' contract though. How many years working with it?
1 fibre? Nah. 1 fibre ain't gonna do anything bud.
There is absolutely no chance of this gutter job giving the OP cancer in half a century.
It's not the scraping of asbestos that causes issues it's the snapping action. Breaking the fibres. There's the issue.
I respectfully disagree.
One large contract? TBH, I don't know how long. The builder bloke said the doctors reckoned that's when he became infected, if that's the right word.
By 'one fibre', I mean it only takes one fibre out of the (possibly) millions breathed in and out to stick in the lungs and that fibre may be so small it can be only seen under a microscope.
The scraping of asbestos, there's video's on you tube that show that fibres are released into the air from a scraping action. That's why there is no recommended safe exposure level to asbestos. The breaking or snapping of asbestos obviously produces much more. All in all, it's unknown what levels of exposure are hazardous which is why there is no safe level of exposure.