2-Ethoxyethanol

2-Ethoxyethanol (ethylene glycol monoethyl ether, EGEE) was first synthesized in the early 20th century as part of the family of glycol ethers — compounds with ether and alcohol functional groups that give them excellent solvent properties for water-borne and oil-based coatings systems. [1] It was commercially important from the 1930s onward as a component of paints, lacquers, varnishes, cleaning products, and jet fuels (it improves low-temperature flow properties). In the 1970s and 1980s, it and its acetate (2-ethoxyethyl acetate) were used extensively as solvents in semiconductor photolithography processes in the electronics industry. The health concerns emerged from multiple directions simultaneously in the late 1970s and early 1980s: animal studies at industry-sponsored and government research programs found that glycol ethers in this class caused testicular atrophy, suppressed spermatogenesis, caused bone marrow toxicity (leading to aplastic anemia), and were teratogenic (caused birth defects). [2] These findings were corroborated by occupational epidemiology studies of semiconductor workers, shipyard painters, and printing workers that found elevated rates of male infertility, increased miscarriages in female workers, and blood cell abnormalities. The EPA classified 2-ethoxyethanol as a HAP and a reproductive toxicant. [3] Major manufacturers began phasing it out in the late 1980s in favor of propylene glycol ethers (like propylene glycol n-propyl ether) that do not have the same metabolic pathway to alkoxyacetic acids and lack the reproductive toxicity.

Painters and coating workers, semiconductor photolithography technicians (historically), printing workers, and chemical manufacturing workers had the highest occupational exposures via inhalation of vapors and skin absorption. The compound is absorbed readily through skin. Consumer exposure occurred historically from some paints and varnishes but has largely been eliminated through reformulation. Some older industrial products may still contain it.

2-Ethoxyethanol is metabolized to ethoxyacetic acid (EAA), which is the primary toxic species responsible for the testicular and bone marrow effects. EAA inhibits fatty acid beta-oxidation and has specific toxic effects on rapidly dividing cells (sperm cells in the testes, hematopoietic cells in bone marrow). [2] The result is dose-dependent testicular atrophy with impaired spermatogenesis in males, and suppression of blood cell production (aplastic anemia) with chronic exposure. In pregnant animals, it crosses the placenta and causes developmental defects. Occupational studies documented elevated miscarriage rates among women working with these glycol ethers in semiconductor cleanrooms before exposure controls were implemented.

Historical semiconductor workers, painters, and printing workers who worked before the phase-out of EGEE products had the highest exposures. Current workers in industries that may still use older formulations face ongoing risk. Pregnant workers and workers planning to have children should be particularly cautious.

1. Identify and eliminate products containing 2-ethoxyethanol (ethylene glycol ethyl ether) from your workplace — propylene glycol ether substitutes are readily available and much less toxic. 2. If working with products that may contain glycol ethers, review Safety Data Sheets for specific ingredient identification. 3. Pregnant workers and those trying to conceive should be reassigned away from jobs with glycol ether solvent exposure. 4. If exposure is unavoidable, wear chemical-resistant gloves and use local exhaust ventilation — skin absorption is significant even from vapors. 5. Urinary ethoxyacetic acid measurement is available in some occupational health programs for exposure confirmation.