By Sophia Sidhu
As an undergraduate student researcher for the UCLA Center for the Study of Women’s Chemical Entanglement group, I am currently conducting research on the presence of toxic chemicals in modern synthetic detergent products. Alexandra Polasko, a Ph.D. student in Environmental Engineering, recently spoke with me about her research on the biodegradation of 1,4-dioxane, a toxic chemical prevalent in detergent, cosmetics, and groundwater.
What is 1,4-dioxane?
1,4-dioxane, also known as dioxane, is a colorless, flammable liquid that is often used as a solvent or a solvent stabilizer and with metal degreasers to reduce the grinding and degradation of metal-on-metal parts. The chemical is prevalent in a wide range of industries, ranging from the military to food production to the tech industry. Due to improper disposal, Polasko says, 1,4-dioxane has contaminated vast amounts of our groundwater. It is also a contaminant produced as a byproduct in the manufacturing of surfactants used in cosmetics, detergents, and shampoos (Chameides).
What are the health impacts of 1,4-dioxane?
Short-term exposure to high levels of 1,4-dioxane can result in nausea, drowsiness, headache, and eye, nose, and throat irritation. Animal studies have shown increased incidence of tumors in the nasal cavity, liver, and gallbladder, and as well as increased fetal toxicity after exposure to 1,4-dioxane. The Environmental Protection Agency (EPA) and the US Department of Health and Human Services have both classified 1,4-dioxane as “likely to be carcinogenic to humans” by all routes of exposure (“Technical Fact Sheet – 1,4-Dioxane”). The U.S. Department of Health and Human Services has, additionally, stated that “1,4-dioxane is reasonably anticipated to be a human carcinogen based on sufficient evidence of carcinogenicity from studies in experimental animals” and that there is sufficient evidence to identify both the liver and the kidneys are the target organs that are vulnerable to short-term exposure to 1,4-dioxane via ingestion, inhalation, or absorption through the skin (Wilbur et al.).
Who is most at risk for 1,4-dioxane exposure?
Polasko explained, “Every type of contaminant, whether it’s a carcinogen or suspected carcinogen, affects women more. We’re smaller generally, so a smaller dose of a chemical will affect us more than it will men. We have a lot more fat tissue which stores chemicals, we get pregnant…The things that affect us affect us tenfold more than they do men.” In addition to this, women have historically handled products that contain contaminants, such as laundry detergents and makeup, more than men. Polasko elaborated, “I would say the roots of exposure for women and the risks that these exposures present are magnified more than they are for men.”
In addition to this, groundwater contamination tends to be more prevalent near low-income housing, meaning low-income communities face increased exposure to toxic contaminants such as 1,4-dioxane and the adverse health effects that accompany such exposure. This issue is further exacerbated by the fact that “safer,” “greener” products are often costly and thus out of reach for these economically disadvantaged populations. In this sense, 1,4-dioxane exposure is manifests itself into an issue of environmental justice (Polasko).
What are the primary sources of exposure to 1,4-dioxane and how are these exposures regulated?
In 2015, 675,000 pounds of 1,4-dioxane were released in the United States, with 9% released to air, 5% released to water, and the remaining 86% released to land (“Scope of the Risk Evaluation for 1,4-Dioxane”). While 1,4-dioxane degrades rapidly in the air, it degrades quite slowly in water and soil and is persistent in the environment and, most notably, in groundwater (“Factsheet 1,4-Dioxane”). As a result, nearly 7% of the public water supply is contaminated with 1,4-dioxane. (Adamson et al.). While the EPA recommends that the level of 1,4-dioxane in drinking water not exceed 4 milligrams per liter, there is no established federal drinking water standard (Wilbur et al.). Polasko explained, “Each state can set whatever limit they want for 1,4-dioxane, which is kind of a bummer because some states regulate it very well and some states do not.” California falls into the former category, with its Proposition 65 establishing a safe daily exposure of 30 micrograms as part of its Safe Drinking Water and Toxic Enforcement Act (Chameides).
Food is another major source of 1,4-dioxane exposure, through residues on crops treated with pesticides, manufactured additives, and packaging materials (Chameides). The Food and Drug Administration (FDA) has set a limit on 1,4-dioxane at 10 ppm in food products and additives (Wilbur et al.).
Finally, The Centers for Disease Control and Prevention (CDC) identifies shampoo, cosmetics, detergents, and household items as sources of everyday exposure to 1,4-dioxane. A recent survey by the Campaign for Safe Cosmetics found levels of 1,4-dioxane ranging from 0.27 to 35 ppm in 32 out of 48 tested consumer products. Other studies have reported that household laundry detergents, shampoos, soaps, and skin cleansers contain 1,4-dioxane levels ranging from 6 to 160 ppm (“1,4-Dioxane in Cosmetics: A Manufacturing Byproduct”). The FDA has not released any recommendation for 1,4-dioxane levels in cosmetics and personal care products, and relies on voluntary industry cooperation instead (Wilbur et al.).
What current research is being done on 1,4-dioxane?
Current research efforts are aimed at developing methods to remove 1,4-dioxane from groundwater. Polasko’s research focuses on using bacteria to biodegrade 1,4-dioxane present in the ground, a process referred to as bioremediation. Existing methods of cleaning up water contaminants include granular activated carbon which essentially works as a sponge that soaks up unwanted chemicals and techniques that involve pumping out water and treating it with different chemicals (Polasko). While effective, these methods are extremely expensive, as well as destructive to the environment. Bacteria, however, is a cost-effective, efficient solution to the cleaning of contaminated water. Bacteria is able to not only soak up contaminants, but also break them down and mineralize them. The bacteria that Polasko works with uses 1,4-dioxane as a food source and is therefore able to sense where 1,4-dioxane is present in groundwater. Polasko’s research focuses on creating a mixed “superculture” that can both aerobically and anaerobically degrade 1,4-dioxane and other contaminants present in groundwater, in order to develop a more cost-efficient and rapid approach to bioremediation. Polasko is currently working on a fluorescent or color-coded testkit that will allow her to take a drop of water and identify beneficial microbes in the environment. Identifying this “good bacteria” would allow her to optimize the growth of such bacteria, a process also known as natural attenuation, that would facilitate the breakdown of 1,4-dioxane and other contaminants (Polasko).
How can I reduce my exposure to 1,4-dioxane?
Because 1,4-dioxane is not an ingredient added to products, but rather a contaminant or byproduct produced while products are being manufactured, the FDA does not require it to be listed as an ingredient on product labels. To avoid 1,4-dioxane in cosmetics, personal care products, and cleaning products, consumers should avoid products with ingredients with the prefix or designations “PEG,” “eth” (such as “myreth,” “oleth,” “laureth,” “ceteareth,” and “polyethylene)” “polyethylene glycol,” “polyoxyethylene,” or “oxynol” (Webb). Additionally, consumers should buy products that are certified under the USDA National Organic Program, since products with 1,4-dioxane cannot meet this certification (Miller). Another useful resource is https://www.ewg.org/skindeep/#.WrtRk9PwaRs which allows consumers to search the personal care products they use and see what chemicals, including 1,4-dioxane, are present.
It is important that consumers are aware of the chemicals that are in the products they handle on a daily basis. As Polasko explained, “You should care [about 1,4-dioxane] because is very well-studied and can cause many different, severe health impediments, so you don’t want to be drinking that for years and years and years. You should care because it’ll affect you, it’ll affect your family, it’ll affect your community. You might not realize the effects until years down the road, which is really scary. A lot of times, staying healthy is catching things early on and not letting a certain type of ailment progress. It’s really important to be an engaged citizen, if you can. I know it’s hard, especially for low-income people when they have two jobs and three kids and don’t have time to look up something on the internet and spend 10 hours researching it. But even identifying small changes can make it easier to nudge people to try; that is why people should care.”
Sophia Sidhu is a UCLA undergraduate studying Human Biology and Society, Medicine, and Public Health. She is a member of CSW’s Chemical Entanglements Undergraduate Student Group. In Winter 2018, Sophia created an interactive timeline on the History of Synthetic Detergents.
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