Draft Nanomaterial Case Study Released For Comment

On July 2 , 2012, EPA announced a 60-day public comment period for EPA's case study on multiwalled carbon nanotubes in flame-retardant coatings used in upholstery textiles. The draft document on the study, issued by EPA's National Center for Environmental Assessment (NCEA), does not draw conclusions regarding potential risks or hazards of multiwalled carbon nanotubes; rather, it aims to identify what is known and unknown about the nanotubes to support future research. EPA says the draft document, which is being released for public comment and peer review, is not final. The Agency will consider comments it receives when finalizing the case study. In addition, EPA will hold an information exchange meeting to discuss the draft document and to provide information on the nanomaterial case study.

According to EPA, the draft document follows previous efforts on engineered nanoscale materials, or nanomaterials. Nanomaterials are materials that measure between 1 and 100 nanometers and often possess unusual, if not unique, properties that arise from their small size. Like all materials, EPA says, nanomaterials offer the potential for both benefits and risks.

EPA's 2007 Nanotechnology White Paper included the following recommendations regarding the risk assessment of nanomaterials:

1.  Develop case studies based on publicly available information on one or several intentionally produced nanomaterials and identify information gaps to help map areas of research that would support the sick assessment process; and
2. Hold a series of workshops involving a substantial number of experts from several disciplines to assist in these processes.

To meet these recommendations, NCEA has also prepared the Nanomaterial case studies “Nanoscale Titanium Dioxide in Water Treatment and in Topical Sunscreen” [Final] in 2010, and “Nanoscale Silver in Disinfectant Spray” [External Review Draft] in 2012.

The comment period for the draft document begins July 2, 2012, and ends August 31, 2012. The public information exchange meeting will be held on October 29, 2012 at the EPA facility in Research Triangle Park, North Carolina.

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Final Health Assessment For Tetrachloroethylene (Perc) Released

U.S. Environmental Protection Agency (EPA) has released the final health assessment for tetrachloroethylene (also known as perchloroethylene, or perc) to EPA’s Integrated Risk Information System (IRIS) database. The assessment replaces the 1988 IRIS assessment for perc and for the first time includes a hazard characterization for cancer effects. Perc is a chemical solvent widely used in the dry cleaning industry. It is also used in the cleaning of metal machinery and to manufacture some consumer products and other chemicals. The final assessment characterizes perc as a “likely human carcinogen.” The assessment provides estimates for both cancer and non-cancer effects associated with exposure to perc over a lifetime.

EPA did not believe that wearing clothes dry cleaned with perc will result in exposures which pose a risk of concern. EPA has already taken several actions to reduce exposure to perc. EPA has clean air standards for dry cleaners that use perc, including requirements that will phase-out the use of perc by dry cleaners in residential buildings by December 21, 2020. EPA also set limits for perc allowed in drinking water and levels for cleaning up perc at Superfund sites throughout the country, which will be updated in light of the final IRIS assessment.

In the future, the toxicity values reported in the perc IRIS assessment will be considered in:

• Establishing cleanup levels at Superfund sites where perc is a contaminant,
• Revising EPA’s Maximum Contaminant Level (MCL) for perc in drinking water, and
• Evaluating whether to propose additional limits on air emissions of perc.

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Final Health Assessment For Trichloroethylene TCE

U.S. Environmental Protection Agency (EPA) has released the final health assessment for trichloroethylene (TCE) to the Integrated Risk Information System (IRIS) database. The final assessment characterizes the chemical as carcinogenic to humans and as a human noncancer health hazard. This assessment has undergone several levels of peer review including, agency review, interagency review, public comment, external peer review by EPA’s Science Advisory Board in January 2011, and a scientific consultation review in 2006 by the National Academy of Sciences.

TCE is one of the most common man-made chemicals found in the environment and is frequently found at Superfund sites across the country, TCE’s movement from contaminated ground water and soil, into the indoor air of overlying buildings (known as vapor encroachment), is of concern to regulators. TCE toxicity values as reported in the assessment will be considered in:

• Establishing cleanup methods at the 761 Superfund sites where TCE has been identified as a contaminant


• Understanding the risk from vapor intrusion as TCE vapors move from contaminated groundwater and soil into the indoor air of overlying buildings


• Revising EPA’s Maximum Contaminant Level for TCE as part of the carcinogenic volatile organic compounds group in drinking water, as described in the agency’s drinking water strategy


• Developing appropriate regulatory standards limiting the atmospheric emissions of TCE – a hazardous air pollutant under the Clean Air Act
  

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EPA Proposing Adding Vapor Intrusion To CERCLA Hazard Ranking

U.S. EPA is proposing to amend the ranking system used to assess potential “Superfund” sites to include potential vapor intrusion. The Hazard Ranking System (HRS), required by the Superfund statute, is the primary mechanism used by EPA to assess the relative threat associated with actual or potential releases of hazardous substances. Sites that score 28.50 or greater under the HRS are eligible for inclusion on the National Priorities List (NPL). The NPL is intended primarily to guide the EPA in determining which sites warrant further investigation. A score of 28.50 does not represent a specified level of risk but is a cutoff point that serves as a screening-level indicator of the highest priority releases or threatened releases.

The HRS includes four scoring pathways - ground water, surface water, air and soil exposure. Additional pathways have been identified by EPA as posing significant threats to human health and the environment, and one such pathway is vapor intrusion. Vapor intrusion occurs when contaminants enter into indoor spaces, generally residences, from environmental sources such as contaminated ground water or contaminated soil.

Historically, EPA's Superfund program has responded to vapor intrusion contamination by two mechanisms: (1) through its emergency response program at sites not on the NPL, or (2) through sites placed on the NPL because of other pathway-related risks. In May 2010, the Government Accountability Office (GAO) issued a report that concluded that if vapor intrusion sites are not assessed and, if needed, listed on the NPL, some seriously contaminated hazardous waste sites with unacceptable human exposure may not otherwise be cleaned up. In response, EPA is proposing to add a new HRS pathway so that sites with vapor intrusion contamination can be evaluated for inclusion on the NPL.

EPA initiated rulemaking in January 2011, and current expects final rules to be completed by January 2012.

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