Dow Corning INTERNAL

Via Electronic Mail and Certified Mail

March 1, 2012

Maria J. Doa, Ph.D.

Director

Chemical Control Division

Office of Pollution Prevention and Toxics U.S. Environmental Protection Agency 1200 Pennsylvania Ave., NW Washington, DC 20460

Re: Proposed Terms of Environmental Monitoring Proposal for Certain Cyclic Siloxanes

Dear Dr. Doa:

On behalf of the member companies 1 of the Silicones Environmental, Health and Safety Council of North America (SEHSC) 2 , this letter follows on our January 31, 2012 submission to the U.S. Environmental Protection Agency (EPA) and our re cent communications regarding the development of an environmental monitoring proposal for certain cyclic s iloxanes. In Attachment 1 to this letter, we are providing proposed terms of an Enforceable Consent Agreement (ECA) for an Environmental Monitoring Program for Octamethylcyclotetrasiloxane (D 4 ) and Decamethylcyclopentasiloxane (D 5 ).

The purpose of the proposed Environmental Monitoring Program is to provide additional information on the presence and concentration of D 4 and D 5 in the environment and on sources of and pathways to the

environmental concentrations of D 4 and D 5 . The proposed Environmental Monitoring Program is based on generic Conceptual Site Models (CSMs) developed for D 4 and D 5 manufacturing, processing and formulating (MPF) facilities and municipal wastewat er treatment plants (WWTPs), existing monitoring data and available science on the environmental properties of D 4 and D 5 , feedback we have received to date from EPA, and consultation with an environment al consulting firm. The proposed Environmental Monitoring Program would augment the existing inte rnational environmental monitoring program for D 4 and D 5 being conducted by the global silicones industry under a voluntary product stewardship initiative (VPSI). 3

Under the proposed Environmental Monitoring Program, monitoring will be conducted at four locations that correspond to D 4 /D 5 MPF sites owned/operated by SEHSC member companies that are direct

1 Bluestar Silicones USA Corporation; Dow Corning Corporation; Evonik Go ldschmidt Corporation; Milliken & Company*; Momentive Performance Materials Inc.; Shin-E tsu Silicones of America, Inc.; and Wacker Chemical Corporation. *Milliken & Compan y recently acquired SEHSC member company, SiVance, LLC.

2 SEHSC is a not-for-profit trade as sociation comprised of North American silicone ch emical producers and importers. For more than 30 years, SEHSC has promoted the safe use of silicones through product stewardship and environmental, health and safety research. A primary fo cus of SEHSC is to coordinate scientific research on health, safety and environmental issues involving silicones.

3 Additional information on environmental monitoring bei ng conducted under the VPSI is provided in Attachment

2.dischargers of process wastewater. At each of the designated locations, there will be two sampling events involving the collection and analysis for D 4 and D 5 in effluent at the MPF’s site’s outfall and in sediment, surface water, and biota (benthic and fish species) in the receiving waters.

Environmental monitoring will also be conducted at five locations that correspond to Municipal WWTPs meeting certain specified criteria. At each of those locations, there will be two sampling events involving the collection and analysis for D 4 and D 5 of the following: WWTP influent, effluent, and biosolids; and surface water, sediment, and biota in the receiving waters. At one of the sites, air monitoring will be conducted.

We are looking forward to the March 7, 2012 meeting we have scheduled with EPA to review and discuss the specific elements of and rationale for the proposed Environmental Monitoring Program. In the meantime, if you have any questions regarding th is submission, please do not hesitate to contact

me.

Sincerely,

Karluss Thomas

Executive Director

Enclosures Attachment 1 – Proposed Terms of Enforceable Consent Agreement for D 4 /D 5 Environmental Monitoring Program Attachment 2 – Global Silicones Industry International Voluntary Product Stewardship Initiative