Most homeowners are aware of the risk of handling asbestos insulation, a common part of home construction from the 1940’s to 70’s. Construction workers may be even more keenly aware of the connection between airborne asbestos fibers and deadly mesothelioma than homeowners. But, while asbestos insulation can be easy to identify (and is no longer used in new construction), a recent article in the International Journal of Occupational and Environmental Health is a reminder of the potential danger that still exists in a less obvious place: joint compound.
Joint compound is the paste-like substance that is used to smooth the seams between sheets of drywall. For decades, many manufacturers added chrysotile asbestos fibers to joint compound to make it thicker and more spreadable and to increase its strength and resistance to heat, fire and corrosion. This practice continued until the late 1970’s. The joint compound or “mud” as it is called in the construction trade, was then covered with drywall tape, which was also sometimes made with asbestos for the same reasons.
But this combination turned out to be a serious mesothelioma threat, especially to construction workers who used it. Joint compound was typically sold in powdered form, which had to be mixed with water to make it spreadable. Wet joint compound is less of a mesothelioma threat, but the powdered form certainly was. Tens of thousands of workers unknowingly inhaled mesothelioma-causing asbestos fibers in joint compound powder before it was pulled from the market. Now, even though asbestos-containing joint compound is no longer sold, the product still presents a risk. Disturbing joint compound used on old dry wall can release asbestos.
In his article, Dr. Dahlgren and coauthor Trevor Peckham remind physicians treating suspected mesothelioma cases not to overlook joint compound as a potential source of exposure. Although drywall itself was never made with asbestos, contractors and do-it-yourself remodelers with older homes should be aware of the potential mesothelioma risk in drywall dust because of the joint compound. The EPA has said that there is no safe level of asbestos exposure.