In a February 11, 2017 letter to U.S. EPA, New York Governor Andrew Cuomo indicated that if U.S. EPA didn’t move promptly to establish a federal maximum contaminant level (MCL) for 1,4-dioxane, New York would be forced to set its own MCL for drinking water in the state. Governor Cuomo pointed to a perceived regulatory gap, noting that New York has expended tremendous resources to address unregulated emerging contaminants such as 1,4-dioxane, PFOA and PFOS. The Governor also noted that water systems serving fewer than 10,000 people are not required to test for unregulated contaminants such as 1,4-dioxane but that New York was moving forward with a plan to require all public water systems on Long Island to test for these unregulated contaminants regardless of size. 1,4-dioxane is alleged to have been found in 40 percent of the public water supplies in Suffolk County.
1,4-dioxane is one of several emerging contaminants that does not currently have an MCL. 1,4-dioxane is a stabilizer that is commonly associated with the chlorinated solvent trichloroethane (TCA). However, it is also commonly found in shampoos, cosmetics, and other personal care products. In the absence of federal regulation, 1,4-dioxane regulatory levels vary from state to state. For example, Michigan recently lowered its 1,4-dioxane regulatory limit from 85 parts per billion (ppb) to 7.2 ppb. Other states have lower limits still, with Massachusetts having set a regulatory limit for 1,4-dioxane of 0.3 ppb.
This patchwork of standards illustrates the challenges that the regulated community faces in the absence of federal action to set an acceptable MCL for 1,4-dioxane and other emerging contaminants. It remains to be seen if the Trump administration will follow through with its expressed intent of relying to the states to implement and enforce environmental rules and regulations or if the administration will recognize the benefits to the regulated community of consistency, at least with respect to drinking water standards.