14Dioxane

1,4-Dioxane is a cyclic ether with the formula C4H8O2. It consists of a six-member ring containing two oxygen atoms at positions 1 and 4. It is a colorless, flammable liquid with a faint ether-like odor, miscible with water and most organic solvents, and a boiling point near 101°C. It is widely used as a polar aprotic solvent in chemical synthesis and as a stabilizer in some chlorinated solvents.

Industrially, 1,4-dioxane is typically produced as a byproduct during the manufacture of ethylene oxide and related products. It can occur as a trace contaminant in various solvents, plastics, and cosmetics, especially those derived from or processed with ethylene oxide. Because it is highly water-miscible, it is difficult to remove by simple distillation and can persist as a contaminant in consumer products and in the environment.

Uses of 1,4-dioxane include serving as a solvent in polymerization, pharmaceutical synthesis, coatings, and laboratory procedures. It has historically been found in cosmetics and personal care products as a solvent or processing aid, though regulatory actions have sought to limit or remove its presence due to safety concerns.

Health and environmental considerations are central to its regulation. 1,4-Dioxane is considered a probable or possible human carcinogen by several health authorities. Exposure can occur via inhalation, skin contact, or ingestion, with potential risks to both workers and consumers. Environmentally, it is relatively persistent in water and can be difficult to remove by conventional wastewater treatment, and it is toxic to aquatic life at certain concentrations. Regulatory approaches generally emphasize minimizing exposure and residual levels in products and wastewater.