Objective: Propylene glycol (PG) is a widely used solvent, chemical intermediate and carrier substance for foods, pharmaceutical and cosmetic products. Professional and occupational exposure to PG aerosol and vapor may occur from theatrical smoke generators and during application of deicing products to airplanes. While PG is considered to have low toxicity, the results of one study suggested that brief (1-min) exposure to PG mist elicited ocular and respiratory effects in humans. Because the high concentrations and brief exposure duration in that study were not representative of most occupational exposures, a controlled experimental exposure study was conducted to clarify or confirm the earlier findings.
Materials and methods: Ten males and 10 females were exposed to PG aerosol for 4 hrs at 20 and 100 mg/m3 and 30 min at 200 mg/m3. Total PG exposure concentrations (droplets plus gas phase) were 95.6, 442.4 and 871 mg/m3 for the three conditions, respectively. Participants rode a stationary bicycle to simulate physical effort at regular intervals during exposure. Objective measures evaluated in this study included ocular irritation via eye blink task and eye photography and pulmonary function via spirometry, while subjective measures included health symptoms ratings, irritation and dryness ratings of eyes, nose, throat and mouth.
Results: Objective measures of pulmonary function and ocular irritation did not reveal any exposure-related changes. Exposure-related changes in symptom reporting were observed; however, the highest symptom ratings did not exceed "slight" on the scale.
Conclusions: The results indicate at the concentrations and acute durations tested, PG does not affect human respiratory function or produce ocular irritation.
Keywords: 1,2-propanediol; Propylene glycol; aerosol; ocular irritation; respiratory irritation.