The Influence of Humidity on Assessing Irritation Threshold of Ammonia.

Christian Monsé,Kirsten Sucker,Hans Berresheim,Jürgen Bünger,Thomas Brüning,Birger Jettkant,Frank Hoffmeyer

doi:10.1155/2016/6015761

Abstract

A large number of occupational exposure limit values (OELs) are based on avoiding of sensory irritation of the eyes and the upper respiratory tract. In order to investigate the chemosensory effect range of a chemical, odor and sensory irritation thresholds (lateralization thresholds, LTs) can be assessed. Humidity affects olfactory function and thus influences odor thresholds; however, a similar effect has not been shown for sensory irritation thresholds. The purpose of the present study was to explore whether LTs for ammonia vapor vary depending on the water vapor content of the inspired stimulus. Eight healthy nonsmoking volunteers were simultaneously exposed to ammonia vapor through one nostril and clean air through the other and were asked to determine which nostril received the chemical. Within experimental runs, ascending ammonia concentrations (60–350 ppm) that were either dry or humidified were administered at fixed time intervals. Geometric mean LTs obtained at wet (181 ppm) or dry (172 ppm) conditions did not differ significantly (P = 0.19) and were within the range of those reported by previous studies. These results suggest that humidity is not a critical factor in determining sensory irritation thresholds for ammonia, and future studies will examine if these findings are transferable to sensory irritation thresholds for other chemicals.

Highlights

A large portion of chemical substances, for which occupational exposure limits have been established, are based on avoiding of sensory irritation (Dick and Ahlers [1]; Edling and Lundberg [2]; Gaffney and Paustenbach [3])
These results suggest that humidity is not a critical factor in determining sensory irritation thresholds for ammonia, and future studies will examine if these findings are transferable to sensory irritation thresholds for other chemicals
In a recent pilot study, we investigated the feasibility of a calibration gas generator to determine the odor and sensory irritation threshold of ammonia [16]

Summary

Introduction

A large portion of chemical substances, for which occupational exposure limits have been established, are based on avoiding of sensory irritation (Dick and Ahlers [1]; Edling and Lundberg [2]; Gaffney and Paustenbach [3]). Psychophysical approaches that, for example, contribute to the determination of odor and sensory irritation thresholds may provide information on the irritant potency of a chemical. Determining the chemosensory effect range reveals concentration-related transitions from olfactory to trigeminal stimulation and the particular ranges of concentrations where these changeovers take place, which is unknown for many chemicals (van Thriel et al [6]). According to the model proposed by Shusterman [7], substances with sensory irritation thresholds lower than odor thresholds can be classified as potent irritants. By determining the chemosensory effect ranges for 15 sensory irritants and comparing the medians and the 5th and 95th percentile range with the German MAK values (“maximale Arbeitsplatz-Konzentration”: maximum workplace concentration), van Thriel et al [6] demonstrated that the MAK

Objectives

Methods

Results

Discussion

Conclusion