A recommended occupational exposure limit for formaldehyde based on irritation

Area of Science:

• Occupational Health
• Toxicology
• Environmental Health

Background:

• Regulatory agencies and professional societies recommend occupational exposure limits (OELs) for formaldehyde.
• A panel of experts was convened to establish an OEL that prevents irritation.

Purpose of the Study:

• To determine an occupational exposure limit (OEL) for formaldehyde that prevents irritation.
• To evaluate existing scientific literature and mathematical models for formaldehyde exposure.
• To provide recommendations for safe formaldehyde exposure levels in occupational and indoor environments.

Main Methods:

• Critiqued approximately 150 scientific articles on formaldehyde exposure and human irritation.
• Evaluated a mathematical model for predicting safe irritant exposure levels.
• Analyzed data from controlled studies involving human volunteers and occupational settings.

Main Results:

• Eye irritation in most individuals does not occur below 1.0 ppm formaldehyde.
• Moderate to severe irritation of eyes, nose, and throat occurs above 2.0-3.0 ppm.
• At 0.3 ppm (8-h TWA), eye irritation rates are similar to clean air exposure.
• At 0.5 ppm (8-h TWA), the majority of workers (80%) did not experience eye irritation.

Conclusions:

• Recommended an OEL of 0.3 ppm (8-h TWA) and a ceiling value (CV) of 1.0 ppm to prevent formaldehyde-induced irritation.
• Found the ACGIH TLV of 0.3 ppm as a ceiling value to be unnecessarily restrictive.
• Concluded that indoor formaldehyde concentrations below 0.1 ppm should prevent irritation for virtually all individuals.
• Determined no evidence of hypersensitivity or sensitization to formaldehyde via inhalation.
• Observed that individuals with asthma respond similarly to healthy individuals up to 3.0 ppm exposure.