The website below has grave indications for all mineral types of dust. When researching for the U.S. Bureau of Mines almost 50 years ago we were keenly aware that whether it was long or short fibered asbestos it could cause mesothelioma and cancer. The mine owners have spent nearly 50 years denying that the short fiber asbestos does not cause mesothelioma; unfortunately they were quite successful. This report indicates that any glass like dust-chard is capable of doing damage to the lungs. This especially includes Silica Dust.
As you can see from the article MN legislators provided millions of dollars to come up with very creditable research that the miners cannot refute. That is one difference between MN and WI.
This research has grave (pun intended) implications for frac-sand mining.
Thanks Jim D.