"Defining New Methods for Evaluating Impacts of Odors Through Chemosensory Irritation."

Authors: Kelli Hackney, Heidi O'Neill, Gretchen Bruce and Richard Pleus

Conference Presentation: April 24, 2025 in Session 4B: Agriculture, Odors and Landfills

Air Quality Measurement Methods & Technology Conference

Sponsored by the Air & Waste Management Conference

Aurora, Colorado.

ABSTRACT

Residents in communities that surround odor-emitting facilities, such as landfills, commonly report experiencing health effects from exposure to odors. Traditional risk assessment methodologies do not account for the complex mechanisms involved in chemosensation. When a chemical odorant binds to receptors in the olfactory epithelium, it triggers a signaling cascade that can stimulate multiple cranial nerves, particularly the trigeminal (cranial nerve X) or vagus (cranial nerve V) nerves. Stimulation of these nerves can trigger irritation and non-specific health effects (e.g., headache, nausea).

We have developed a method for evaluating whether exposure to odors is likely to cause non-specific health effects. Using hydrogen sulfide as an example, we:

1. Collect grab air samples from community locations in Tedlar bags when odors are detected and analyze using selected ion flow tube mass spectrometry.

2. Compare concentrations of odorous chemicals detected in air samples to odor detection thresholds.

3. Characterize each odorous chemical detected at or above its odor detection thresholds for the potential to stimulate trigeminal and/or vagus nerve endings, where known, based on information from literature review of studies of trigeminal or vagus nerve stimulation. 

Evaluation of chemical odorants that have the potential to stimulate trigeminal or vagus nerve endings and cause chemosensory irritation can provide additional insights into the potential cause of health effects not evaluated using traditional health assessment methodologies.  Our work can be used to help facilities prioritize reductions of the chemical odorants with the highest potential to stimulate the trigeminal or vagus nerves.