Mark Twain noted that there are "Lies, damned lies and statistics." In the world of asbestos and mesothelioma studies, there are lots of statistics. The risk posed by asbestos exposure is terrifically difficult to gauge, because there is no known safe exposure level to asbestos fibers, which means even a single exposure could lead to the development of an asbestos-related disease.
Another difficulty is determining the exact source of the risk. In Minnesota, the region known as the "Iron Range" has produced iron ore from taconite for more than a century. In a recent study, the occurrence of mesothelioma among miners has been found to be unusually high. The miners developed mesothelioma at a rate double what would be expected.
Residents from nearby communities have grown concerned, worried that they too, could face an elevated risk of cancer caused by exposure to dust from the mines. The fear is that they could be the next Libby, Montana; where the entire town was declared a Superfund site, contaminated with asbestos-laden dust from the vermiculate mine that bordered the town.
The study of the iron range appears inconclusive. While the final report has not been released, some scientists were critical at the design of the study, with one commenting that it was like "shooting an arrow at the wall and then drawing the target around it."
It found low levels of mineral dust in the air, but did not detail the types of particles they found.
Residents are disappointed that the studies never seem to produce a "thorough" answer. The researchers noted it was a "characterization study" and not an "exposure study." The miners and residents simply want an answer to the question "is taconite mining causing mesothelioma?" Too often, when it comes to asbestos and mesothelioma studies, the obfuscation and lack of clarity almost seems to be by design.
Startribune.com, "Iron Range air quality study triggers spat among scientists," DAVID SHAFFER and JEREMY OLSON, February 23, 2015