I first heard about the re-emergence of this issue from an acquaintance late last year and started to do a little research on it. The International Agency for Research on Cancer (IARC) issued a statement in October that put forth their finding that included the statement that “… occupational exposure to oxidized bitumens and their emissions during roofing (are) … probably carcinogenic to humans.” The spectrum of this finding is not new. There is a link to the topic from our May 2004 issue below.

Since first learning of the new IARC findings I have been listening to folks I have come to trust over the years, and there are a few things that I am finding a bit troubling. To begin with, let me issue this disclaimer: I am not a scientist or chemist. I do not take a stand on the IARC’s finding in this regard. What you see here is one layman’s opinion and is based on findings that are anecdotal. Anyone with a vested interest in any form of asphalt roofing should keep an eye on this as more findings are bound to emerge from other agencies.

The first thing that bothers me is why this pronouncement and why now? The National Roofing Contractors Association (NRCA) has been actively engaged in the debate over this issue for some time and is at odds with the findings in the IARC’s report. But the IARC is on the record and the roofing industry will have to deal with the fact that the notice is there and the potential for downstream liability is there and is real.

Some manufacturers are reacting to the IARC findings by changing the language in their Material Safety Data Sheets (MSDS) and the NRCA does recommend roofing contractors limit worker exposure to asphalt fumes. This would include having workers wear personal protective equipment to and maintaining a tight control on asphalt temperatures at the kettle.

The “troublesome” things I have learned include that the IARC ruling covers only oxidized bitumen, particularly asphalt, such as we use in the roofing industry both in our hot-melt applications and manufactured roofing products. Road bitumen is not included for some reason, and in spite of the fact that I am not a chemist or scientist, I find that hard to fathom. A road crew working with hot melt bitumen may be exposed to considerably more fumes than the typical roofing crew.

Another thing is the billions of square feet of roofing in service now that must be removed and replaced eventually. Historically we have thought nothing of removing old roofing without much consideration for exposure to the dust that may be present as a result of these operations. Also, will exposure to skin become a problem as well?

Tough questions, but in my view the only thing to do is hang on to see where this all leads. Of course, studying this issue and following the good recommendations of NRCA on the topic are well advised. We will keep an eye on this and will report on it in greater detail in an upcoming issue of Roofing Contractor. In the meantime, here are some resources: