I think that comes back to looking at the inherent hazard approach. That means looking at the substance's inherent hazards rather than taking the approach of what the average exposure is or what the likelihood is of a person being exposed.
If a substance is inherently hazardous, such as mercury, for example, then we need to look at the inherent risks. It's so toxic that there's no debate about whether or not it is, right? But the question is, this welder might be exposed much more than somebody, say, who is living somewhere along the St. Lawrence River. That's a bad example, because the St. Lawrence does have many mercury hot spots, but....