Glycol Ether Toxicology

Excerpt

Glycol ethers have been a versatile and essential solvent group widely utilized in industrial and commercial settings since their initial development in the 1930s. Glycol ethers possess a unique combination of physical properties, including high solvency, low evaporation rates, and miscibility with both water and organic substances. These characteristics make glycol ethers essential in manufacturing various products, including paint and ink formulations, cleaners, cosmetics, pharmaceuticals, circuit boards, and hydraulic brake fluids.

Traditionally, glycol ethers are classified based on their precursor molecules. Ethylene oxide-derived glycol ethers belong to the E-series, while molecules derived from propylene oxide are classified as P-series glycol ethers. The utility of E-series glycol ethers (EGEs), such as methyl-, ethyl-, butyl-, and hexyl-GEs, has diminished due to increasing reports of their toxic effects. EGEs are metabolized into their respective alkoxyacetic acids, producing neurologic, hematologic, renal, hepatic, endocrine, teratogenic, and reproductive effects. Consequently, the relatively safer P-series glycol ethers (PGEs) have mostly replaced EGEs.

PGEs include methyl-, ethyl-, n-propyl-, butyl, and phenyl propylene glycol ethers (see Image. Propylene Glycol n-Butyl Ether Structure). These chemicals are often preferred due to their comparatively lower toxicity profiles. PGEs are commonly found in paints, coatings, semiconductor processes, resins, cleaners, sunscreen, and pharmaceuticals. Propylene glycol has many applications due to its solvent properties. A key example is its use in lorazepam and diazepam infusions.

Glycol ether exposure may occur in both household and occupational settings through inhalation, dermal contact, or ingestion. Occupations most vulnerable to glycol ether exposure include cleaners, printing machine operators, semiconductor manufacturing workers, chemical industry workers, automobile mechanics, cosmeticians, secretaries, and printers.