Ethylene glycol is a clear, colorless, odorless, sweet-tasting liquid. It has low vapor pressures at room temperature and, therefore, low potential for significant inhalation exposure.
Ethylene glycol and propylene glycol have similar physical properties and uses. Their chemical structures differ by only one methyl group (ethylene glycol, HOCH2CH2OH; propylene glycol, CH3CH[OH]CH2OH).
Ethylene glycol does not persist in large amounts in ambient air because breakdown is rapid (half-life in air is 8-84 hours). In environmental exposure situations, its low vapor pressure precludes substantial inhalation exposure at ambient temperatures, and its poor skin absorption prevents significant absorption after dermal contact. Ethylene glycol is miscible with water and will leach through soil to groundwater. It biodegrades rapidly in soil (half-life, 2-12 days). The half-life ranges from 2-12 days in surface water and 4- 24 days in ground water. Because it is not fat soluble and biodegrades rapidly, bioconcentration and bioaccumulation are insignificant (Agency for Toxic Substances and Disease Registry 1997).