Generally, things that cause cancer don't cause cancer when people are exposed to extremely small amounts. From our understanding, this is because the body is

Generally, things that cause cancer don't cause cancer when people are exposed to extremely small amounts. From our understanding, this is because the body is able to tolerate a certain amount of carcinogenic substances before a statistical threshold is reached. In situations where people are only exposed to tiny amounts of asbestos through fiber inhalation, we don't really have good stats on what happens to people who inhale tiny amounts (and these amounts are parts-per-million, found only in a subset of samples). In epi, what ends up happening is that people down-extrapolate using a linear model, outside the linear regime. Testing is normally done by pooling multiple samples. Again, I simply think there's a lack of evidence that anybody did anything crimimal.