Low molecular weight E-series (ethylene glycol derivatives) have been largely replaced with low molecular weight P-series (propylene glycol derivatives) over the last 35 years. [
PMID 15705483] Glycol ethers (E series) include 2-methoxyethanol (EGME), 2-ethoxyethanol (EGEE), 2-butoxyethanol (EGBE), and their acetates. These agents may be absorbed through the skin without causing irritation. The most toxic glycol ethers are reproductive and suspected bone marrow toxins; studies of workers heavily exposed to these chemicals have shown evidence of testicular toxicity, increased risk of birth defects, and pancytopenia. EGME and EGEE are reported causes of pancytopenia in animals and in the workplace; Higher molecular weight glycol ethers cause hemolysis in animal experiments. [LaDou, p. 549] "While there is insufficient evidence to conclude that exposure to glycol ethers results in blood or bone marrow toxicity, common sense dictates that exposure of these agents should be minimized." [Sullivan, p. 758] Of greatest concern are the ethylene glycol ethers EGME, EGEE, and their acetates EGMEA and EGEEA. They cause liver, kidney, blood, and reproductive injury in animals. As photolithography solvents, they were discontinued in the mid-1990s in the semiconductor manufacturing industry and replaced with propylene glycol monomethyl ether acetate (PGMEA) and other solvents. PGMEA is not metabolized to toxic intermediates like the ethylene glycol ethers. It has no known chronic health effects unless it is contaminated by the beta isomer of PGMEA. [Sullivan, p. 450-1] Classified by the European Union as reproductive toxins: EGEE (110-80-5), EGME (109-86-4), DEGDME (111-96-6), EGDME (110-71-4), TEGDME (112-49-2), and 1PG2ME (107-98-2); [Glycol Ethers Online] A 2001 study of 109 workers found "current glycol ether exposure levels were low and not correlated with either seminal quality or hormone levels." [
PMID 17332140] After intentional ingestion of large amounts, glycol ethers cause CNS depression, coma, and severe kidney and liver injury. [Ford, p. 776] The three categories of glycol ethers in this database are Glycol Ethers (E Series), Glycol Ethers (P Series), and Glycol Ethers (Glymes).