Not worried about it. Coal slag is not a Coal Ash. Coal Slag blasting products does not have the heavy metals, lead and other things that some other blast material suppliers have stated. If it did then all the jobs that I have been on in over 20 years having TCLIP test done on all spent abrasive would have showed all the heavy metals and other poisons that some are claiming Coal Slag to have in it. One such Crushed Glass producer has even gone out and sent out large volumes of e-mails to many telling us how bad Coal Slag is and has mentioned one large coal slag producer by name many times in the e-mails which will and can get them in a big legal issue quick. So, I am not one to jump on the band wagon of the crushed glass craze just yet. I have not seen better profiles since the hardness of the crushed glass is not that great over the the other abrasives out there. I still promote the use of Coal Slag products because I have had the spent material tested for years and so far no lead, mercury or other harmful materials have ever showed up on any of the TCLIP test yet. Use what you want, but please do not try to scare people into using something that has just hit the market in the last couple of years. Coal Slag abrasives have been used safely for many many years. Coal Slag is Coal Slag. Coal Ash is something different. Just my two cents. Take it for what it's worth.