Ethylene Glycol

2021-11-26

Ethylene glycol, chemical formula C2H6O2, is a colourless, odourless, syrupy liquid that has a sweet taste. It can exist in the air in vapour form. Other common names for ethylene glycol are glycol and glycol alcohol. [1]

Uses [1]

Ethylene glycol is used to make antifreeze and de-icing solutions for cars, airplanes, airport runways, and boats. It is used in cooling and heating systems, hydraulic brake fluids, electrolytic condensers, plasticisers, polyethylene terephthalate (PET) bottles, lacquers, resins, wood stains, leather dyeing, photographic developing solutions, textile processing, polyester fibres, synthetic waxes, cosmetics, pharmaceutical products, and safety explosives. It is used to create artificial smoke and mist for theatrical productions, and as an ingredient in several processes related to packing, transporting, or holding food. Other uses for ethylene glycol are as a solvent for paints and plastics, a softening agent for cellophane, a stabiliser for soybean extinguishing foam, and an ingredient in printers’ inks, stamp pad inks, and ballpoint pen inks.

Sources and Routes of Exposure [2,3]

Dermal or inhalation exposure to workers may occur during the manufacture or use of the chemical. Ethylene glycol may be discharged into wastewater from its production and use. It may also enter the environment from its uses in deicing airplane runways and from spills and improper disposal of used antifreeze, coolant, and solvents containing ethylene glycol. The major route of exposure for workers applying ethylene glycol products is inhalation. Other major routes include oral exposure and dermal contact with the skin and eyes. Intentional or accidental ingestion of antifreeze has resulted in thousands of poisonings each year.

Toxokinetics [3]

  • Ethylene glycol is quickly and extensively absorbed through the gastrointestinal tract. It is slowly absorbed through the skin. Limited information suggests that it is absorbed across the respiratory tract.
  • Absorbed ethylene glycol is widely distributed throughout the body.
  • It is metabolised in a series of steps that ultimately yield formate, glycine, malate, carbon dioxide and oxalic acid.
  • Elimination of ethylene glycol occurs via exhaled carbon dioxide and urinary excretion of ethylene glycol, glycolic acid, and oxalic acid. The half-life for elimination is 2.5–8.4 hours.
  • Ethylene glycol metabolism is saturated at higher oral doses leading to a shift in excretory pattern with a greater urinary excretion and decreased elimination via expired air.

Health Risks [2]

Acute Effects

Acute exposure of humans to ethylene glycol by ingesting large quantities causes three stages of health effects. CNS depression, including such symptoms as vomiting, drowsiness, coma, respiratory failure, convulsions, metabolic changes, and gastrointestinal upset are followed by cardiopulmonary effects and later renal damage. Acute animal tests in rats, mice, rabbits, and guinea pigs have demonstrated ethylene glycol to have moderate acute toxicity by inhalation or dermal exposure and low to moderate acute toxicity by ingestion.

Chronic Effects

The only effects were noted in a study of individuals exposed to low levels of ethylene glycol by inhalation for about a month were throat and upper respiratory tract irritation. Rats chronically exposed to ethylene glycol in their diet, exhibited signs of kidney toxicity and liver effects. Ocular irritation and lesions and pulmonary inflammation have been observed in rats, rabbits, and guinea pigs subchronically exposed by inhalation. EPA has not established a Reference Concentration (RfC) for ethylene glycol. The Reference Dose (RfD) for ethylene glycol is 2.0 milligrams per kilogram body weight per day (mg/kg/d) based on kidney toxicity in rats.

Reproductive/Developmental Effects

No information is available on the reproductive or developmental effects of ethylene glycol in humans. Several studies of rodents exposed orally or by inhalation showed ethylene glycol to affect animal foetuses. Fetotoxicity manifested as increased preimplantation loss, delayed ossification, and an increased incidence of foetal malformations were reported. The inhalation study, however, noted continuous grooming of the fur, resulting in a high rate of exposure by ingestion as well.

Cancer Risk

An epidemiologic study on renal cancer mortality did not find an increased risk for workers exposed to ethylene glycol. A study by the NTP did not find an increased incidence of tumours in mice exposed to ethylene glycol in the diet. EPA has not classified ethylene glycol for carcinogenicity.

Safety [4]

First Aid Measures

  • Eye Contact: Check for and remove any contact lenses. In case of contact, immediately flush eyes with plenty of water for at least 15 minutes. Cold water may be used. Get medical attention if irritation occurs.
  • Skin Contact: Wash with soap and water. Cover the irritated skin with an emollient. Get medical attention if irritation develops. Cold water may be used.
  • Inhalation: If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention immediately.
  • Ingestion: Do NOT induce vomiting unless directed to do so by medical personnel. Never give anything by mouth to an unconscious person. If large quantities of this material are swallowed, call a physician immediately. Loosen tight clothing such as a collar, tie, belt or waistband.
  • Serious Ingestion: Medical Conditions Aggravated by Exposure: Persons with pre-existing kidney, respiratory, eye, or neurological problems might be more sensitive to Ethylene Glycol.

Notes to Physician:

Support vital functions, correct for dehydration and shock, and manage fluid balance.

The currently recommended medical management of Ethylene Glycol poisoning includes elimination of Ethylene Glycol and metabolites. Elimination of Ethylene Glycol may be achieved by the following methods:

  • Emptying the stomach by gastric lavage. It is useful if initiated within < 1 of ingestion.
  • Correct metabolic acidosis with intravenous administration of sodium bicarbonate, adjusting the administration rate according to repeated and frequent measurement of acid/base status.
  • Administer ethanol (orally or by IV (intravenously)) or fomepizole (4-methylpyrazole or Antizol)) therapy by IV as an antidote to inhibit the formation of toxic metabolites.
  • If patients are diagnosed and treated early in the course with the above methods, hemodialysis may be avoided if fomepizole or ethanol therapy is effective and has corrected the metabolic acidosis, and no renal failure is present. However, once severe acidosis and renal failure occur, hemodialysis is necessary. It is effective in removing Ethylene Glycol and toxic metabolites, and correcting metabolic acidosis.

Exposure Controls and Personal Protection

Exposure Control

  • Provide exhaust ventilation or other engineering controls to keep the airborne concentrations of vapours below their respective threshold limit value.
  • Ensure that eyewash stations and safety showers are proximal to the workstation location.

Personal Protective Equipment

The personal protective equipment recommended for handling ethylene glycol includes: safety glasses, synthetic apron and gloves (impervious). For most conditions, no respiratory protection should be required. However, if material is heated or sprayed and if atmospheric levels exceed exposure guidelines, an approved vapour (air purifying) respirator should be used.

For large spills the following personal protective equipment is recommended: splash goggles, full suit, boots and gloves. Please note that a specialist should be consulted prior to handling this product as suggested protective clothing might not be sufficient.

Regulation [4]

Exposure Limits

United States:

  • TWA: 100 (mg/m3) from ACGIH (TLV)
  • CEIL: 125 (mg/m3) from OSHA (PEL)
  • CEIL: 50 (ppm) from OSHA (PEL)

Australia:

  • STEL: 120 (mg/m3)

United Kingdom:

  • TWA: 52 STEL: 104 (mg/m3)
  • Inhalation TWA: 10 (mg/m3)

References

http://toxtown.nlm.nih.gov/text_version/chemicals.php?id=13

http://www.epa.gov/ttnatw01/hlthef/ethy-gly.html

http://www.atsdr.cdc.gov/toxguides/toxguide-96.pdf

http://www.sciencelab.com/msds.php?msdsId=9927167