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TEG is a liquid higher glycol of very low vapor pressure with uses that are primarily industrial. It has a very low order of acute toxicity by i.v., i.p., peroral, percutaneous and inhalation (vapor and aerosol) routes of exposure. It does not produce primary skin irritation. Acute eye contact with the liquid causes mild local transient irritation (conjunctival hyperemia and slight chemosis) but does not induce corneal injury. Animal maximization and human volunteer repeated insult patch tests studies have shown that TEG does not cause skin sensitization. A study with Swiss-Webster mice demonstrated that TEG aerosol has properties of a peripheral chemosensory irritant material and caused a depression of breathing rate with an RD(50) of 5140 mg m(-3). Continuous subchronic peroral dosing of TEG in the diet of rats did not produce any systemic cumulative or long-term toxicity. The effects seen were dose-related increased relative kidney weight, increased urine volume and decreased urine pH, probably a result of the renal excretion of TEG and metabolites following the absorption of large doses of TEG. There was also decreased hemoglobin concentration, decreased hematocrit and increased mean corpuscular volume, probably due to hemodilution following absorption of TEG. The NOAEL was 20 000 ppm TEG in diet. Short-term repeated aerosol exposure studies in the rat demonstrated that, by nose-only exposure, the threshold for effects by respiratory tract exposure was 1036 mg m(-3). Neither high dosage acute nor repeated exposures to TEG produce hepatorenal injury characteristic of that caused by the lower glycol homologues. Elimination studies with acute peroral doses of TEG given to rats and rabbits showed high recoveries (91-98% over 5 days), with the major fraction appearing in urine (84-94%) and only 1% as CO(2). TEG in urine is present in unchanged and oxidized forms, but only negligible amounts as oxalic acid. Developmental toxicity studies with undiluted TEG given by gavage produced maternal toxicity in rats (body weight, food consumption, water consumption, and relative kidney weight) with a NOEL of 1126 mg kg(-1) day(-1), and mice (relative kidney weight) with a NOEL of 5630 mg kg(-1) day(-1). Developmental toxicity, expressed as fetotoxicity, had a NOEL of 5630 mg kg(-1) day(-1) with the rat and 563 mg kg(-1) day(-1) with mice. Neither species showed any evidence of embryotoxicity or teratogenicity. There was no evidence for reproductive toxicity with mice given up to 3% TEG in drinking water in a continuous breeding study. TEG did not produce mutagenic or clastogenic effects in the following in vitro genetic toxicology studies: Salmonella typhimurium reverse mutation test, SOS-chromotest in E. coli, CHO forward gene mutation test (HGPRT locus), CHO sister chromatid exchange test, and a chromosome aberration test with CHO cells. The use patterns suggest that exposure to TEG is mainly occupational, with limited exposures by consumers. Exposure is normally by skin and eye contact. Local and systemic adverse health e...

Glycols are diols, compounds containing two hydroxyl groups attached to separate carbon atoms. In an aliphatic chain, ethylene glycol, is the simplest glycol. Diethylene, triethylene, and tetraethylene glycols are oligomers of ethylene glycol. Polyglycols are higher molecular weight adducts of ethylene oxide and are distinguished by intervening ether linkages in the hydrocarbon chain. The first commercial application of the Lefort direct ethylene oxidation to ethylene oxide followed by hydrolysis of ethylene oxide remains the main commercial source of ethylene glycol production. The uses for ethylene glycol are numerous. Some of the applications are polyester resins for fiber, PET containers, and film applications; all‐weather automotive antifreeze and coolants, defrosting and deicing aircraft; heat‐transfer solutions for coolants for gas compressors, heating, ventilating, and air‐conditioning systems; water‐based formulations such as adhesives, latex paints, and asphalt emulsions; manufacture of capacitors; and unsaturated polyester resins. The oligomers also have excellent water solubility but are less hygroscopic and have somewhat different solvent properties. The largest commercial use of ethylene glycol is its reaction with dicarboxylic acids to form linear polyesters. In addition to oligomers ethylene glycol derivative classes include monoethers, diethers, esters, acetals, and ketals as well as numerous other organic and organometallic molecules. The propylene glycol family of chemical compounds consists of monopropylene glycol (PG), dipropylene glycol (DPG), and tripropylene glycol (TPG). These chemicals are manufactured as copoducts and are used commercially in a large variety of applications. They are available as highly purified products which meet well‐defined manufacturing and sales specifications. All commercial production is via the hydrolysis of propylene oxide. The propylene glycols are clear, viscous, colorless liquids that have very little odor, a slightly bittersweet taste, and low vapor pressures. The most important member of the family is monopropylene glycol. All of the glycols are totally miscible with water. Propylene glycol, when produced according to the U.S. Food and Drug Administration good manufacturing practice guidelines at a registered facility, meets the requirements of the U.S. Food, Drug, and Cosmetic Act. It is listed in the regulation as a direct additive for specified foods and is classified as generally recognized as safe (GRAS). Because of its low human toxicity and desirable formulation properties it has been an important ingredient for years in food, cosmetic, and pharmaceutical products. Glycols such as neopentyl glycol, 2,2,4‐trimethyl‐1,3‐pentanediol, 1,4‐cyclohexanedimethanol, and hydroxypivalyl hydroxypivalate are used in the synthesis of polyesters and urethane foams. Commercial preparation of neopentyl glycol can be via an alkali‐catalyzed condensation of isobutyraldehyde with 2 moles of formaldehyde (crossed Cannizzaro reaction). 2,2,4‐Trimethyl‐1,3‐pentanediol can be produced by hydrogenation of the aldehyde trimer resulting from the aldol condensation of isobutyraldehyde. The manufacture of 1,4‐cyclohexanedimethanol can be accomplished by the catalytic reduction under pressure of dimethyl terephthalate in a methanol solution. Hydroxypivalyl hydroxypivalate may be produced by the esterification of hydoxypivalic acid with neopentyl glycol or by the intermolecular oxidation–reduction (Tishchenko reaction) of hydroxypivaldehyde using an aluminum alkoxide catalyst. Polyester resins produced from of the glycols, are useful for preparation of coatings exhibiting a combination of hydrolytic stability, excellent weather resistance, and good flexibility.

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