1,4-dioxane, also referred to as dioxane, is a frequently occurring, and problematic water contaminant. It is an industrial solvent that mixes almost perfectly with water. It is a recognized carcinogen in the state of California and as “a likely human carcinogen” by the EPA.
- CAS Registry: 123-91-1
- Minimum Reporting Level: 0.07 µg/L (parts per billion)
- Health Reference Level: 0.35 µg/L
- Guidelines By: Unregulated Contaminant Monitoring Rule 3 (UCMR 3)
- Chemical composition: C4H8O2
What is 1,4-dioxane?
1,4-dioxane, which takes the forms of chemicals like (but not limited to) dioxane, dioxan, p-dioxane, diethylene dioxide, and glycol ethylene ether is an industrial solvent that is perfectly soluble in water. It is a colorless liquid with a faint order, that is described as being “faintly sweet” but is harmful to humans and a likely carcinogen. It appears in water after being used in both industrial and consumer applications, including in products like dye, paint cleaners, grease, antifreeze and
de-icers, as well as both shampoo and cosmetics. It is resistant to biodegradation and because of this and it’s solubility (also known as miscibility) it is often found ahead of other contaminants.
1,4-dioxane in Drinking Water
This compound breaks down quickly when in the air, but it’s highly stable in water, which is one of the reasons it’s featured in a number of public water system (PWS) contaminant violations. The CDC notes that low levels of 1,4-dioxane exposure will cause irriation to the eyes and nose. High levels of exposure could causes damage to the kidney and/or liver and possibly cause death. The CDC as well as agencies like the EPA, International Agency for Research on Cancer (IARC), and the US Department of Health and Human Services (HHS) agree that the compound likely causes cancer in humans but accept that this isn’t fully proven by studies.
1,4-dioxane is assumed to get into drinking water largely from spills, leaky underground storage containers, and manufacturing plant discharge. Because of it’s stability in water it persists, sometimes through processing, and on to tap water.
Many basic home water filter are unable to remove 1,4-dioxane effectively (under 50% removal according to the WHO). Reverse osmosis filters do a better job of removing it from water but do not do a perfect job. The difficulty removing the chemical from water are one reason that have been a push to simply not get it in the water supply in the first place.