Acute effects of exposure to vapours of dioxane in humans

Information on the acute effects associated with the handling of 1,4-dioxane is sparse. Our aim was to evaluate the acute effects of 1,4-dioxane vapours. In a screening study, six healthy volunteers rated symptoms on a visual analogue scale (VAS), while exposed to stepwise increasing levels of 1,4-dioxane, from 1 to 20 ppm. The initial study indicated no increased ratings at any of the exposure levels; we decided to use 20 ppm (72 mg/m3) as a tentative no observed adverse effect level (NOAEL). In the main study, six female and six male healthy volunteers were exposed to 0 (control exposure) and 20 ppm 1,4-dioxane vapour, for 2 hours at rest. The volunteers rated 10 symptoms on VAS before, during, and after the exposure. Blink frequency was monitored during exposure. Pulmonary function, and nasal swelling, was measured before, and at 0 and 3 hours after exposure. Inflammatory markers in plasma (C-reactive protein, and interleukin-6) were measured before and at 3 hours after exposure. In conclusion, exposure to 20 ppm 1,4-dioxane for 2 hours did not significantly affect symptom ratings, blink frequency, pulmonary function, nasal swelling, or inflammatory markers in the plasma of the 12 volunteers in our study.