The likelihood of a worker building a long-term tolerance to Bitrex (denatonium benzoate) from a single 3-to-5-minute annual respirator fit test is virtually zero. Physiological habituation—where the nervous system stops responding to a stimulus—requires frequent, sustained exposure over time. A brief, once-a-year exposure is nowhere near the threshold required to alter a person’s neurological taste receptors.
However, there are a few physiological and procedural factors regarding Bitrex that often get confused with an acquired immunity: