Superfund Acts to Protect Americans from Harmful Vapors 

By Mathy Stanislaus

Under the Superfund program, the Environmental Protection Agency (EPA) protects people who live close to Superfund sites by addressing any threats those sites may pose to soil, air, groundwater and surface water. Approximately 53 million people in the U.S. live within three miles of a Superfund site. So when EPA conducts Superfund investigations and finds significant threats to public health or the environment, we clean them up, control them, or both.

Another environmental concern that EPA addresses under Superfund is subsurface intrusion, which occurs when hazardous substances, pollutants or contaminants migrate from below the ground into overlying structures.

While subsurface intrusion can take multiple forms, vapor intrusion is the most common. Vapor intrusion generally occurs when volatile chemicals migrate from contaminated groundwater or soil into overlying structures. When someone is exposed to vapor intrusion, it can raise his or her lifetime risk of cancer or chronic disease.

EPA addresses subsurface intrusion under Superfund, but until now it was not a criterion for determining whether a site gets added to the National Priorities List (NPL). The NPL is EPA’s list of more than 1,300 of the nation’s most contaminated sites, where we conduct further investigation and possible remediation under the Superfund program.

So today, my office added subsurface intrusion to the Hazard Ranking System (HRS), which is the methodology EPA uses to evaluate and score sites for NPL inclusion. Sites receiving HRS scores above a specific threshold can be proposed to the NPL. Today’s action allows the EPA site assessment program to address two additional types of sites: those that either have only subsurface intrusion issues, and those with subsurface intrusion issues that are coincident with a groundwater or soil contamination problem. Therefore, this change expands options for EPA and our state and tribal partners to evaluate potential threats to public health and the environment from hazardous waste sites. This rulemaking only augments criteria for applying the HRS; it will not affect the status of sites currently on or proposed to the NPL.

Previously, if EPA addressed subsurface intrusion at an NPL site, it was because EPA listed the site on the NPL for a different contamination issue. Now that we factor subsurface intrusion into our HRS scoring, we have enhanced our ability to prioritize and address it.

The last HRS revision, in 1990, evaluated four exposure pathways: surface water, groundwater, air and soil. It did not include a subsurface intrusion component, as the science was not sufficiently advanced. In the interceding years the research has progressed to a point where today’s HRS revision stands on solid science.

Over its 35-year history, Superfund has made enormous contributions to improve the health, environment and economies of America’s communities. Today’s action moves the Superfund program forward and provides the public added protection and peace of mind.


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