Not all smokers get lung cancer. But with large enough samples, smokers turn out to be much more likely to get lung cancer than non-smokers. That's why we say that smoking causes lung cancer. It's not as if someone has actually watched a particle of tobacco interact with someone's lung cells to turn them cancerous in real time.
_heimdall
Smoking isn't a contagious pathogen.
sydbarrett74
Second- and third-hand smoke mimic contagion.
_heimdall
That has nothing to do with contagion, that's just a sign that the impact of smoke inhalation isn't limited to the one sucking on a cigarette.
Contagion would mean that the smoke can infect the host, replicate, and spread to others. That's not how second hand smoking works.
Not all smokers get lung cancer. But with large enough samples, smokers turn out to be much more likely to get lung cancer than non-smokers. That's why we say that smoking causes lung cancer. It's not as if someone has actually watched a particle of tobacco interact with someone's lung cells to turn them cancerous in real time.