State-by-State Regulations for 1,4-Dioxane in Drinking Water | Bryan Cave Leighton Paisner

As illustrated in the May 11, 2022 press release regarding the Industrial Excess Landfill Superfund site in Uniontown, Ohio, the U.S. Environmental Protection Agency (“EPA”) and state environmental agencies have begun directing potentially responsible parties to conduct investigations to address the presence of 1,4-dioxane in drinking water and groundwater. Notably, some of these investigations are conducted at previously closed sites where the chemical was not initially identified as a contaminant of concern.

To protect the environment and avoid liability, any company in industries that use or produce this chemical should determine if it needs to modify its operations to reduce or eliminate 1,4-dioxane.

In the absence of an enforceable federal drinking water standard for 1,4-dioxane, many states have begun to regulate 1,4-dioxane in drinking water. The result is a patchwork of regulations and standards. This Customer Alert investigates the Maximum Contaminant Levels (“MCLs”), Remediation, Guidance, and Notification levels for 1,4-dioxane in drinking water in the United States.

I. EPA Health Advisory

The EPA has declared that a concentration of 35 micrograms per liter (µg/L) of 1,4-dioxane (listed by the EPA as 0.035 milligrams per liter) should not be exceeded in drinking water. According to the EPA, this number corresponds to an estimated lifetime incremental cancer risk for an exposed individual of 1 in 10,000.

The EPA health advisory is not binding, but is intended to provide technical information to state agencies and other public health officials regarding the health effects of the chemical. The decision to promulgate a federal MCL for the chemical will depend on EPA’s evaluation of the three statutory criteria for regulation: (1) adverse health effects to affected persons; (2) a level of public health concern; and (3) provide a meaningful opportunity to reduce health risks.

II. State regulations

In the absence of a federal MCL for 1,4-dioxane, the drinking water regulatory landscape consists of an array of widely varying standards and regulations promulgated by the states. For example, the lowest allowable concentration is 0.3 µg/L (Massachusetts) and the highest is 7.2 µg/L (Michigan).

The map and graph are current to June 21, 2022.

Virginia has enacted legislation to establish MCLs for 1,4-dioxane for drinking water, so implementing regulations in that jurisdiction may be forthcoming. New Jersey is in the process of adopting an MCL for 1,4-dioxane for drinking water. A few states (eg Ohio) have included 1,4-dioxane in their generic hazard-derived standards. These values ​​are generally indicative and may be used by state agencies when ordering parties to remediate sites.

States Without Drinking Water Regulations or Enforceable 1,4-Dioxane Guidelines (as of publication date):

Alabama, Alaska, Arizona, Arkansas, Colorado, Delaware, Georgia, Idaho, Illinois, Indiana, Iowa, Kansas, Louisiana, Maryland, Mississippi, Missouri, Montana, Nebraska, New Jersey, New Mexico, North Carolina, North Dakota , Ohio, Oklahoma, Oregon, Pennsylvania, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Vermont, Virginia, Washington, West Virginia, Wisconsin and Wyoming


III. How do these limits impact businesses?

MCLs set the maximum concentration of a given contaminant that can be present in drinking water. Public treatment plants (“POTW”) and drinking water systems are ultimately responsible for compliance with applicable MCLs and must ensure that drinking water distributed to the public meets these limits. To accomplish this, POTWs and state agencies often include discharge limits in permits from upstream dischargers to the POTW or other potable water systems to ensure that the effluent the treatment facility receives can be properly filtered and processed to comply with MCLs.

Companies that have currently or historically used 1,4-dioxane, or have reason to believe that the chemical may be present in their process wastewater effluent, should assess the following considerations:

  • Whether their wastewater discharges, after treatment by the POTW or other treatment facilities, are ultimately discharged into sources used for drinking water;
  • If their landfill contains any of the 1,4-dioxanes that are regulated in their jurisdiction; and
  • If they are likely to be subject to permit conditions limiting the permissible concentration of 1,4-dioxane in their waste water discharges.

This assessment will allow a company to determine if it needs to modify its operations to reduce or eliminate 1,4-dioxane from its waste stream in order to comply with an existing standard or in anticipation of likely future permit conditions.

IV. Conclusion

Regulation of 1,4-dioxane in drinking water will continue over the next few years as more research is conducted into the potential health impacts and regulators at the federal and state levels develop a better understanding of the prevalence of 1,4-dioxane. dioxane in drinking water.

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