PCE Toxicity Value Review

On February 10, 2012, U.S. EPA published a final Health Assessment for Tetrachloroethylene (Perchloroethylene, or “Perc” or PCE) on the IRIS database (http://cfpub.epa.gov/ncea/iris/index.cfm?fuseaction=iris.showQuickView&substance_nmbr=0106). In the new Health Assessment, EPA provides revised toxicity values for oral exposures (a reference dose [RfD] for non-cancer and a cancer slope factor [CSF] for cancer risk) and for inhalation exposures (a reference concentration [RfC]for non-cancer and an inhalation unit risk factor [URF] for cancer).

Several years ago, while EPA’s Health Assessment was still in progress, assessment of tetracholorethylene in indoor air arose as a critical issue for a number of MCP sites.  The Bureau of Waste Site Cleanup (BWSC) requested that the Office of Research and Standards (ORS) review the inhalation unit risk factor (URF, for evaluating cancer risk from exposure to air contaminants) in use at the time.  ORS toxicologists conducted the review of the scientific literature available at the time, obtained a peer-review of the ORS assessment, and published a revised inhalation unit risk value in 2008 (http://www.mass.gov/dep/toxics/chemrs.htm).

In addition to the URF published in 2008, ORS has recently reviewed and updated the RfC used to calculate MassDEP’s Threshold Effects Limits (non-cancer) for tetrachloroethylene (http://www.mass.gov/dep/toxics/stypes/telaal.htm).  This review considered all of the toxicological data currently available.

Some of the toxicity values published in EPA’s Health Assessment differ significantly from those developed by MassDEP.  ORS plans to review the basis for the values provided by EPA before adopting final values.  MassDEP expects to complete the review by the end of March. Until then, MassDEP recommends the continued use of the MassDEP cancer slope factor of 5 x 10-2 (mg/kg/day)-1 and the inhalation unit risk of 1 x 10-5 (µg/m3)-1 for site-specific risk assessments conducted under the Massachusetts Contingency Plan (310 CMR 40.0000).

Any questions may be directed to BWSC.Information@state.ma.us.


Vapor Intrusion Discussion Summary

A summary of the February 9, 2012 discussion about revisions related to the Vapor Intrusion pathway is now available. These are notes from the discussion and not MassDEP’s interpretation. For those who participated in the conversation, please read the notes and comment on anything we may have missed or misinterpreted. For those who missed the meeting, this is a great chance to add your voice to the discussion! Either way, please use the comment block below so that the wider community can benefit from your thoughts & observations.

MS Word version: VI-Discussion-2012-02-09-notes (63 KB)

Adobe PDF version: VI-Discussion-2012-02-09-notes (373 KB)

Questions to Ponder for Workgroup Meeting

A list of topics and discussion items for the February 9, 2012 workgroup meeting has been posted on the MCP Reg Reform Blog.

Workgroup Meeting

During the development of the Vapor Intrusion Guidance, MassDEP staff and Workgroup members identified several potential changes to the MCP that could strengthen and streamline the notification, assessment, cleanup & closure of vapor intrusion sites.  A Workgroup meeting has been scheduled to discuss such potential regulation revisions:

  • Thursday, February 9th, 1:00 – 3:00 pm @ MassDEP, One Winter Street, Boston, MA 02108

In addition, this and other reg reform initiatives will be on the agenda for the January 26, 2012 Waste Site Cleanup Advisory Committee meeting (9:30 AM – 12:00 PM, MassDEP Boston).

Next Meeting: 12/20/2011

MassDEP has scheduled a Vapor Intrusion Workgroup Meeting for Tuesday December 20th at 9:30 at 1 Winter Street, 2nd floor.

The purpose of the meeting is to:

  •  discuss the comments received on the December 2010 Draft Vapor intrusion Guidance and MassDEP’s responses;
  • discuss the changes made to the December 2010 Draft and provide an overview of the Interim Final Vapor Intrusion Guidance;  and
  • present conceptual MCP amendments related to vapor intrusion being considered by MassDEP.

MassDEP intends to post the comments/responses and Draft Interim Guidance before the end of the year. Workgroup members  will informed when these documents are made available.

Thank you for your patience and see you on the 20th.


Comments on Draft Vapor Intrusion Guidance

MassDEP would like to thank you for submitting comments on the Draft Vapor Intrusion Guidance Document (December 2010).  We are currently organizing and reviewing the comments and we intend to compile a written summary of the comments and provide written responses which outlines how best to revise the guidance to address them. We will keep the workgroup updated as to our progress and we are planning on presenting and an overview of the comments at the April 2011 Waste Site Cleanup Advisory Committee meeting.

Your ongoing interest in this important effort is greatly appreciated… Stay tuned for additional updates as we go through this process.

Thanks again…


Gerard Martin


Presentation: VI Guidance Update

On Tuesday, January 11, 2011, Gerard Martin (MassDEP) was the guest speaker at the Licensed Site Professional Association (LSPA) monthly membership meeting. The presentation was titled, “Vapor Intrusion Guidance Update”, and was intended to provide a summary of what’s in the draft guidance document to facilitate the LSPA members’ review and comment.

The PowerPoint slides from the presentation are now available for download below, in both PDF and PowerPoint formats.

PDF version: 1-11-11_LSPA_FINAL_G-Martin (781 KB, pdf)
PowerPoint version:  1-11-11_LSPA_FINAL_G-Martin (1.6 MB, pptx)