ABSTRACT
INTRODUCTION The detection of external chemicals by humans is accomplished by smell (olfaction), taste (gustation), and chemical sensory irritation (1-4). The latter was originally labeled the common chemical sense (5). More recently, it has been referred to as chemical nociception (6). Nevertheless, at low levels of stimulation, the sensations evoked might not be perceived as painful or even irritating. Since this sensory modality rests on chemically induced somesthesis, or chemical “feel,” the quite appropriate and descriptive term “chemesthesis” is now often employed (3,7,8). In the nasal, ocular, and oral mucosae, chemesthesis is principally mediated by the trigeminal nerve (cranial nerve V). Thus, it is common to refer to trigeminal chemosensitivity when addressing this topic (9,10). In the aggregate, eye, nose, and throat irritation has been referred to as “sensory irritation” and, along with secondary reflex symptoms in that anatomical distribution, constitute an important symptom constellation in so-called “problem buildings,” as well as being the basis for a substantial fraction of occupational exposure standards (11,12). Nasal chemesthesis, the main focus of this chapter, arises from stimulation with airborne chemicals. Many of these, although not all of them, are volatile organic compounds (VOCs). The chemesthetic sensations that they can evoke in the nose are typically pungent, that is, sharp. They include stinging, freshness, coolness, burning, piquancy, tingling, irritation, prickling, and the like.
