Posted By Dave Merchant I presume you're talking about Bitrex(TM) - aka Denatonium Benzoate. There are a few cases on file of asthmatic attacks induced by acute exposure, and one report of contact skin rash, but incidences are very low, and Bitrex is an approved FDA additive used to prevent children from consuming dangerous household chemicals like antifreeze - so has passed extensive human tests even though it's intended precisely to avoid the substance being swallowed. As with all irritants, the amount of exposure is the factor, as well as individual sensitivity. Take off the mask and breathe in the contents of the fit-test hood, and you'll regret it like nothing else on earth. Fit-test users should also be told to breathe through their open mouth with tongue extended so they detect the bitter taste as soon as possible, rather than inhaling through their nose and potentially increasing their dose before noticing.

Posted By gerry d Bill, I have worked in the asbestos industry for around 18 years and have never experienced any issues with adverse reactions to agents used in face fit testing. As as company we have though moved away from qualitative testing and onto quantative testing only. Obviously this meant a change in the type of RPE but was most certainly a step in right direction in every sense. Chapter 5 of HSG247 will give you more information. Gerry