Agency for Toxic Substances and Disease Registry
Case Studies in Environmental Medicine (CSEM) 

Ethylene Glycol and Propylene Glycol Toxicity
What is Ethylene Glycol?

Learning Objectives

Upon completion of this section, you should be able to

• describe the properties of ethylene glycol.

Definition

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).

Synonyms

Ethylene glycol is also known as

• ethylene alcohol
• glycol alcohol
• glycol
• 1,2-dihydroxyethane
• 1,2-ethanediol

Toxicity

Properties

Ethylene glycol

• dissolves in water and alcohol
• can hold large amounts of heat before boiling
• lowers the freezing point of water
• absorbs twice its weight in water

Uses

Ethylene glycol is used as

• a drying agent,
• a component of automotive fluids such as antifreeze, coolants, and hydraulic fluids,
• de-icing agents,
• a chemical intermediate,
• a solvent in inks, stains, pesticides, fire extinguishers, foams, polishes, and adhesives, and
• a heat-transfer fluid in air conditioning units and solar energy systems.

It is also used in producing polyester fibers, films, resin products, cosmetics, and fat extractants.

Environmental Fate

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).

Key Points

• Because of ethylene glycol’s low vapor pressure and poor skin absorption, poisonings normally occur by ingestion.
• Ethylene glycol degrades rapidly in the environment.

Progress Check