New York state officials have prodded USEPA to establish a maximum Contaminant Level (MCL) for 1,4-dioxane in drinking water. Although EPA has published a long- and short-term health advisory for 1,4-dioxane, New York state officials claim that if the federal government does not act regarding this contaminant, they will. In December 2018, the New York State Drinking Water Quality Council recommended a new drinking water standard for 1,4-dioxane at 1 microgram per liter (µg/L).
In 1998, the State of California was notified about a 1,4-dioxane detection in a groundwater well; subsequently over the past decade, it has been found in a number of wells, mostly in southern California. In 2002, the presence of 1,4-dioxane in wastewater became problematic for a groundwater recharge project in southern California, prompting a need for additional water treatment.
How does 1,4-dioxane get into our water supplies?
1,4-Dioxane is a chemical found in consumer products such as shampoo and liquid soaps, and in many industrial chemicals including 1,1,1-trichloroethane, dyes, fats, paint, fumigants and pesticides. 1,4-Dioxane may exist as a contaminant in many consumer products as a byproduct of the manufacturing process.
Due to its widespread use, 1,4-dioxane is expected to be found in the groundwater in areas historically known to be contaminated with chlorinated solvents. In addition, 1,4-dioxane may be released in unintended spills, septic systems, and wastewater discharges via personal care products. Because 1,4-dioxane has been detected in drinking water, states have established notification limits. For example, California has set a notification level of 1 µg/L. Certain requirements and recommendations apply to water systems containing 1,4-dioxane greater than 1 µg/L. Similarly, other states, such as New York, New Jersey and New Hampshire are setting new, low limits.
Drinking water methods
There are several EPA methods for 1,4-dioxane. Since it is not a regulated parameter there are no approved drinking water methods. However, EPA Method 522, developed for the third Unregulated Contaminant Monitoring Rule (UCMR3) is the generally accepted method. EPA Method 522 uses Solid Phase Extraction (SPE) followed by highly selective and sensitive gas chromatography mass spectrometry (GCMS) with selective ion monitoring (SIM). This technique passes a 100 to 500 milliliter sample through an SPE cartridge, effectively removing interferences and concentrating the 1,4-dioxane for reporting limits as low as 0.07 µg/L.