Hardly anyone has heard of them, but millions of pounds of glymes are used every year to make household products throughout the United States.
Now time is running out for glymes – at least when it comes to new uses in consumer products.
The U.S. Environmental Protection Agency announced in July that it plans to clamp down on these little known ingredients used by a broad array of industries. Used mostly as solvents, glymes are found in lithium batteries, inkjet cartridges, brake fluid, paints and carpet cleaners. They are also widely used to make prescription drugs, printed circuit boards and microchips.
The EPA determined that three glymes pose a “high concern to workers, consumers and children” because they may have reproductive or developmental effects. A U.S. study more than a decade ago found links to miscarriages among workers in semiconductor manufacturing.
The EPA has proposed a new rule for glymes as one of its few weapons authorized by the federal Toxic Substances Control Act. If adopted, it would let the agency restrict new uses of 14 glymes in the U.S. marketplace.
Glymes belong to a broad family of chemicals called “glycol ethers” typically used as solvents in manufacturing. Two – monoglyme and diglyme – caused reproductive and developmental damage in rodent studies. Animal studies on a third glyme, ethylglyme, show developmental toxicity as well as the potential for gene mutation.
For the 11 others, no health effects have been reported, but the EPA included them in its rule as a precaution because they have a similar chemical structure.
Richard Denison, a biochemist and senior scientist at the Environmental Defense Fund, a national environmental group, called glymes “a quite nasty group of chemicals.”
“They are potent reproductive and developmental toxicants, and they’re also used in a lot of consumer products. The range of uses includes products that the ordinary customer would use and be exposed to,” Denison said.
Glymes have come under U.S. government scrutiny as particularly hazardous to workers, including those that manufacture semiconductors, printing ink, automotive care products, paints and pharmaceuticals.
A study of 6,000 workers in 14 plants led by scientists from the University of California, Davis in the late 1980s and early1990s linked glyme mixtures to miscarriages among semiconductor manufacturing workers.
The researchers found a pattern of increased miscarriages among women exposed to mixtures of ethylene-based glycol ethers including diglyme. The results of the multi-year study paid for by the Semiconductor Industry Association were published in 1995 in a full issue of the American Journal of Industrial Medicine.
“I’m glad to see attention to this because the agents are no less toxic than they were 10 years ago,” said Dr. Marc B. Schenker, a UC Davis professor of medicine and chairman of the Department of Public Health Sciences, who led the study.
Schenker said the semiconductor industry made changes in manufacturing after his study and another study at IBM with similar findings. Other industries use these solvents more heavily than semiconductor manufacturers do, but they haven’t put in place the same controls, he said.
Little is known about how much the public is exposed to glymes through consumer products and releases into the environment.
Agency officials say new uses could increase people’s exposure through skin absorption or inhalation. Diglyme has been detected in drinking water, so consumption is a possible route, too, they say. While exposure to monoglyme in lithium batteries is limited because batteries are sealed, there is possible exposure from handling polishing clothes or printed paper and breathing emissions from a household paint can, vehicle exhaust or factories.
“Because glymes are used in a wide array of applications to which people may be routinely exposed, we are concerned about the effects that could result from additional uses of these chemicals, especially the reproductive and developmental impacts of monoglyme, diglyme and ethylglyme,” Steve Owens, assistant administrator for EPA’s Office of Chemical Safety and Pollution Prevention, told Environmental Health News.
In animal studies, monoglyme caused thymus atrophy, bone marrow suppression and testicular degeneration, according to EPA documents. Diglyme caused decreased sperm production, poor growth of fetuses, reduction in red blood cell count and wasting away of bone marrow, the spleen and the thymus gland. Ethylglyme was linked to increased numbers of malformed rodent fetuses, including damage to organs and bones, EPA documents say.
Owens said the EPA is also “concerned about the potentially harmful impacts of the other 11 glymes,” due in part to the absence of information on toxicity and exposures.
Under federal law, the EPA may adopt a “significant new use rule” for a substance when there is concern that additional uses could cause harm by significantly increasing human exposure or environmental degradation. Over the past decade, the EPA has issued 47 of these rules for 360 chemicals.
The new proposal would require manufacturers, importers and processors of the 14 glymes to secure EPA’s approval before launching any new uses. The agency then would determine whether they would pose additional harm to workers and the public.
The rule could only eliminate new uses in consumer products. Existing uses, such as lithium batteries, paint strippers and printing inks, would be exempt from the rule.
Up to 10 million pounds each of monoglyme and diglyme are manufactured or imported to the U.S. every year. They are generally used as solvents -- dissolving agents -- or used in the manufacture of other chemicals.
The new EPA rule “could have significant implications for companies involved with paints and coatings, household batteries, printing ink, sealants, adhesives, and motor vehicles,” Elise Rinfleish, an associate at Alston + Bird, a nationwide environmental law firm, wrote on the company’s website.
“Not only are a broad array of industries covered under the proposed [rule], the scope of covered activities is extensive,” she wrote.
The U.S. and European manufacturers, including Clariant Corp., Novolyte Technologies and Dow, did not grant interview requests from Environmental Health News. They declined to release the brand names of products containing glymes.
However, a search of databases found glymes in Duracell Procell Lithium 9-Volt Battery, Energizer Lithium-Iron Disulfide Battery 1.5 Volt, Ultralife Lithium Manganese Dioxide Cells and Batteries and Wagner DOT 4 Brake Fluid.
Monoglyme is used as a solvent in electrolytes in sealed lithium ion batteries, according to EPA documents. It also is used in the etching of printed circuit boards in the electronics industry, in treating aluminum surfaces to make them more resistant and in the synthesis of anti-AIDS drugs.
"Glymes are amongst the strongest solvents available anywhere,” Clariant Corp., says on its website. “They have properties such as high thermal and chemical stability that recommend them in a variety of pharmaceutical production reactions.”
Letters to the EPA show that Clariant representatives made assurances that no monoglyme is present in pharmaceuticals.
Diglyme is used as a solvent in printing and inkjet inks and inkjet cartridges. It is used in brake fluid, paints and other coatings, plastics, adhesives and sealants, and as a solvent during the production of hypertension, asthma and anti-depression drugs. Novolyte Technologies representatives also have told the EPA that no diglyme is present in pharmaceuticals.
Ethylglyme has no consumer uses that could be confirmed by the EPA. However, the EPA has received reports that it is used as a solvent in paints, adhesives, coatings, shellacs, resins, detergents, dyes and polycarbonate products. Its production is on the rise, and it has been found in water sources in Ohio, Illinois and Ontario, Canada.
In the European Union, products containing monoglyme or diglyme already are regulated. Their labels must say “may impair fertility” or “may cause harm to the unborn child.”
If the U.S. rule is adopted, the EPA can require companies to conduct tests to rule out unreasonable risk before it will approve new uses of the compounds. The agency also reviews green chemistry substitutes, and already has observed a trend toward replacing ethylene-based glycol ethers with less toxic propylene-based glycol ethers, the agency says.
The EPA uses “significant new use rules” because the 35-year-old Toxic Substances Control Act doesn’t offer any other remedy for eliminating dangerous chemicals, said Denison at the Environmental Defense Fund.
For years, environmentalists have sought reform of the act, but it has remained unchanged by Congress since it was adopted in 1976.
The new glymes rule was held up in the Office of Management and Budget for six months, taking twice as long as allowed for review, according to environmental groups. The EPA will seek comment on its proposal until Sept. 9, and then send the proposal back to the budget office for final review.
“The rule-making process itself requires agencies to jump through a host of hoops to get a regulation passed,” Denison said.