Sensory irritation: risk assessment approaches

Area of Science:

• Environmental Health
• Toxicology
• Occupational Health

Background:

• Sensory irritation of eyes and upper airways is a common complaint in buildings and a parameter for occupational exposure limits.
• This irritation stems from the stimulation of trigeminal nerve receptors, with chemically reactive compounds generally being more potent.
• Understanding these effects is vital for maintaining healthy indoor environments.

Purpose of the Study:

• To review the scientific basis for setting occupational exposure limits related to sensory irritation.
• To evaluate the methods for predicting human sensory irritation from animal studies and human exposure data.
• To discuss the application and evidence base for uncertainty factors in deriving safe exposure levels.

Main Methods:

• Analysis of animal studies to predict human sensory irritation concentration-effect relationships.
• Evaluation of human short-term and long-term exposure data for sensory irritation thresholds and effects.
• Review of factors influencing sensory irritation, including chemical reactivity and odor cues.

Main Results:

• Concentration-effect relationships for sensory irritation are often steep, with thresholds and suprathreshold effects measurable in humans.
• Sensory irritation can develop over time, and odor cues can influence reported symptoms.
• A combined estimate from multiple study types is recommended for determining the no-observed-adverse-effect level (NOAEL).

Conclusions:

• The standard uncertainty factor (UF) of 5 (leading to a UF of 10 for sensitive individuals) may need adjustment based on evidence, as published UFs have reached 300.
• Combined effects of sensory irritants can be approximated as additive.
• Further research is needed to establish evidence-based uncertainty factors for robust occupational exposure limits.