1,4-Dioxane: The Latest Emerging Vapor Intrusion Issue

1,4-Dioxane is an emerging contaminant.  Like “traditional” volatile organic compounds, it has the potential to volatilize and enter indoor air.  This article explores why businesses should consider conducting a VI assessment when evaluating 1,4-Dioxane releases for site investigations or real property due diligence.

For additional background regarding 1,4-Dioxane, please refer to BCLP’s prior Client Alert, which discusses how this chemical has been used in certain products and industries.

I. Why 1,4-Dioxane is a Concern

According to the U.S. Environmental Protection Agency (“EPA”), 1,4-Dioxane moves rapidly from soil to groundwater.  This factor is an important consideration because VI issues arise when contaminants appear beneath a building and vaporize into indoor air within the building.

EPA and many state agencies have determined that 1,4-Dioxane is a health risk to human beings at certain concentrations, although it is not listed as a known human carcinogen at this time.  Studies used by EPA and the National Library of Medicine have determined that 1,4-Dioxane causes cancer in animals.  Below is a summary of current agency conclusions as to human health:

II. 1,4-Dioxane and VI Issues

A VI issue of concern occurs when contaminated gases in the subsurface intrude into a building’s indoor air at concentrations that approach or exceed health benchmarks.  In 2016, EPA established advisory Vapor Intrusion Screening Levels (“VISL”) for hundreds of chemicals, including 1,4-dioxane.   

1,4-Dioxane is a potential concern at industrial facilities with groundwater contaminated with 1,4-Dioxane.  But VI problems can be particularly acute as a result of the migration of contamination beneath residences, schools, or other sensitive uses.  Risks are heightened if the contaminated plume is shallow or results in standing water in residential basements.  According to a 2022 article addressing this issue: 

Vapor Intrusion (VI) poses significant environmental problems that can degrade indoor air and pose human health risks. … 1,4-Dioxane [is] a widely used volatile organic compound (VOC) that is found in groundwater, however, this compound has not received much attention in indoor air and measurement methods are not well developed.

Importantly, VI issues have caused a number of seemingly finalized sites to be reopened.  Both the ATSDR and  EPA have issued VI guidance, in part to respond to these situations.  This underscores how important VI issues can be in evaluating 1,4-Dioxane releases. 

III. State Regulations

The federal government has not yet issued an enforceable standard for 1,4-Dioxane in drinking water, much less for VI. 

As conveyed in the chart below, some States have established 1,4-Dioxane VI regulations or standards even absent federal guidance.  These State initiatives seek to limit indoor air exposure issues based on different residential, industrial, or occupational standards.  

This map and the information below is current as of July 19, 2022.

States with No Specific 1,4-Dioxane VI Regulations (as of the date of publication): 

Alabama, Arizona, Arkansas, California, Connecticut, Delaware, Florida, Georgia, Idaho, Iowa, Kansas, Kentucky, Louisiana, Minnesota, Mississippi, Missouri, Montana, Nevada, New Hampshire, New York, North Dakota, Ohio, Oklahoma, Rhode Island, South Carolina, South Dakota, Tennessee, Texas, Utah, Virginia, Washington, West Virginia, Wisconsin, and Wyoming.

IV. Conclusion

As an emerging contaminant, 1,4-Dioxane is gaining the attention of regulators. Increased regulator attention will drive private party focus in the course of real estate acquisitions and leases, environmental remediation projects, and third-party neighbor concerns.  Your business can take the following actions:

• Consider 1,4-Dioxane (and VI risks in particular) within environmental due diligence in connection with any real estate acquisitions or leases;
• Evaluate any applicable 1,4-Dioxane VI standards for States in which you own or operate real estate; and
• The latest ATSM Standard (E1527-21) used by parties in many real estate transactions encourages, but does require, testing for VI issues in certain circumstances.  The ATSM Standard also acknowledges that emerging contaminants, such as 1,4-Dioxane, may be evaluated if regulated by state law.  

If you have any questions regarding 1,4-Dioxane, please contact Phil Karmel (212-541-2311), John Kindschuh (314-259-2313), or Erin Brooks (314-259-2393).