ABSTRACT
The risk assessment and regulation of 1,4-dioxane as an environmental contaminant depend on assumptions regarding human exposure and toxic potency. The toxicity of 1,4-dioxane in humans is evaluated by considering studies in laboratory animals and limited data from human exposures. This chapter briefl y summarizes the toxicological data for 1,4-dioxane. The uptake and behavior of this chemical within the body are discussed (i.e., toxicokinetics). Toxicity studies in humans are presented; these consist of case reports of occupational poisoning, volunteer studies of acute inhalation exposure, and limited epidemiology studies of occupational workers. The acute effects of highdose exposures (less than one month in duration) on laboratory animals are also described. These studies are relevant in identifying the potential outcomes of accidental or industrial poisoning from 1,4-dioxane, but do not provide useful information about lower-level environmental exposures. Subchronic and chronic laboratory animal studies are designed to evaluate the potential for health effects to result from exposure to different doses over longer periods of time. These studies are generally used to assess long-term environmental exposures when human data are limited or absent. Brief study summaries are provided for the subchronic and chronic toxicity studies conducted for 1,4-dioxane. Also discussed are mechanistic studies that provide some insight into the potential mechanisms of action leading to toxicological outcomes.
