Via Electronic Mail and Certified Mail

October 15, 2015

Jeffery T. Morris, Ph.D.

Deputy Director, Office of Pollution Prevention & Toxics

U.S. Environmental Protection Agency

1200 Pennsylvania Avenue, NW (MC-7401M)

Washington, DC 20460

Re: Follow Up to September 11, 2015 Letter

Testing Consent Order for Octamethylcyclotetrasiloxane (D4) CASRN 556-67-2

40 C.F.R. 799.5000; EPA-HQ-OPPT-2012-0209

Dear Jeff:

The Silicones Environmental, Health, and Safety Center (SEHSC) is firmly committed to the D4 

Enforceable Consent Agreement (ECA) for developing environmental exposure data to support a 

scientifically-robust environmental risk assessment for the siloxane D4. Undertaking such an 

environmental monitoring program is, to our knowledge, unprecedented under the Toxic 

Substances and Control Act (TSCA) and an ECA. We remain committed to the full monitoring 

program that was agreed to in the ECA.

As we have expressed on numerous occasions, including during the face-to-face meeting in 

Richmond on August 14, SEHSC and the ECA signatory companies urge the Agency to approve

the Study Plan and Quality Assurance Project Plan (QAPP) so that the full monitoring program 

that was agreed to in the ECA can move forward. 

The Testing Program described in the Study Plan, including the five indirect discharge sites, 

fully satisfies the terms of the ECA. As explained below, the Testing Program in the Study Plan:

 Identifies five “indirect discharge” wastewater treatment plants (WWTPs) that satisfy the 

criteria of the ECA;

 Enables the Program to achieve the purpose and goals of the overall ECA; and

 Provides the Agency with monitoring data reflecting the full D4 value chain, which 

would allow EPA to conduct a robust risk assessment.

In this formal response to your September 11, 2015 letter to SEHSC, we address the points raised 

by that letter below and in the enclosed attachment. Our feedback on the technical comments 
Page 2 of 7

included in the spreadsheet accompanying your September 11 letter is also enclosed. As we 

explain throughout the following response, we strongly disagree with the Agency’s assertions 

that there are “problems associated with the five indirect discharge sites” and such problems 

“may not be correctable”; and we do not support dropping those sites from the monitoring 

program. 

I. The Sites Proposed for Monitoring in the Study Plan Will Allow The 

Agency to Conduct a Robust Risk Assessment that Reflects the Full Value 

Chain.

We disagree with EPA’s assertion in the September 11th Letter that there would be “little or no 

value” in including the proposed Indirect Discharge WWTPs in the Testing Program “if it cannot 

be verified that bulk D4 is being processed” at the associated indirect dischargers. We note that 

the vast majority of the D4 processors in the U.S. are similar to those identified for the five 

Indirect Discharge sites included in the Study Plan (i.e., they are processing/formulating 

polymers that contain D4). These sites represent the majority of the D4 value chain. 

Accordingly, it is difficult to fathom why environmental data collected at those WWTPs would 

not be very useful to inform a robust risk assessment. 

With respect to EPA’s concern about “bulk” D4 processors, the Study Plan already includes 

three WWTP locations that receive wastewater from facilities that process or formulate “bulk”

D4 (i.e., three of the direct discharge sites described in Appendix 1 to the ECA). Thus, the 

Agency will be provided with data regarding potential releases from environmental 

concentrations associated with “bulk” D4 processors. Whether the associated WWTP is on-site 

or off-site should not limit the utility of the monitoring data for conducting an ecological risk 

assessment.

II. The 5 “Indirect Discharge” Wastewater Treatment Plants (WWTPs) 

Identified in the Study Plan Satisfy the Criteria Set Out in Section VII.B 

and Appendix 2 of the ECA. 

The ECA resulted from a lengthy negotiation process. During that process, the parties discussed 

multiple potential approaches for conducting a monitoring program before memorializing an 

agreement in a legal instrument (i.e., the ECA). The final ECA signed by the Agency and the 

Signatory Companies specifically defines the scope of the Testing Program. It includes detailed 

appendices that describe the locations to be tested and how the testing is to be conducted. 

Specifically, with respect to “Indirect Discharge” facilities, Section VII.B of the ECA states 

[a]s described further in Appendix 2 to this ECA, environmental testing will be 

conducted on samples collected at five (5) WWTP locations that use activated 

sludge to treat wastewater from indirect discharge sites that include D4 

processors (including product formulators).
Page 3 of 7

Appendix 2 to the ECA elaborates by specifying that the “Indirect Discharge” WWTP locations 

must be chosen based on six criteria. Those were and remain the only selection criteria agreed to 

by the parties. We understand that EPA believes that the five Indirect Discharge sites proposed 

in the Study Plan do not satisfy the requirement that 

[a]ll wastewater treatment sites selected for monitoring must be currently 

processing wastewater from one or more industrial sites known to be a D4 

processor or formulator as documented through industrial user surveys or by 

other readily available information. <emphasis added>

As discussed further below, EPA’s position is based on an incomplete understanding of the 

siloxane chemistry and a flawed reading of the ECA. 

SEHSC has reviewed with EPA on multiple occasions the process used for identifying and 

confirming WWTP locations, the challenges encountered in the process, and, how, 

notwithstanding those challenges, each proposed site satisfies the ECA criteria.1 EPA’s 

reluctance to move forward by not approving the Study Plan is perplexing. The five Indirect 

Discharge sites described in the Study Plan meet the actual criteria agreed upon in the ECA and 

collecting and analyzing samples at those sites and the other nine monitoring sites described in 

the Study Plan will enable the Testing Program to achieve the purpose set out in Section V of the

ECA.

a. EPA’s criticism of the Industrial User Survey used to confirm site selection is 

based on an incomplete understanding of siloxane chemistry.

In the September 11, 2015 letter, the Agency claims that an indirect discharger’s specific 

confirmation in a completed survey response that it is processing one or more materials 

identified as containing D4 does not mean that the site meets the ECA criterion of “known to be 

a D4 processor or formulator.”

2

 To support this contention, the Agency argues that “some of 

the groups of the chemicals included in the survey [which were presented as being known to 

contain D4] may be synthesized solely with linear silanes [sic], meaning that it is not necessary 

for cyclical silanes [sic] to be present.”3 However, EPA’s criticism is predicated on an 

incomplete understanding of siloxane chemistry. Regardless of the method used to 

commercially produce silicone polymers and copolymers, including the materials identified on 

the survey, D4 is present. Thus, the survey instrument was accurate as presented. 4 

 

1 May 20, 2015 conference call between SEHSC and EPA; June 5, 2015, Follow Up letter from SEHSC to EPA; June 

25, 2015, conference call between Jeff Morris and Karluss Thomas; July 13 2015, conference call between Jeff 

Morris and Karluss Thomas; August 14, 2015 site visit and meeting; August 31, 2015, Follow Up letter from SEHSC 

to EPA.

2

See p. 2 of the September 11, 2015 letter from Jeff Morris. 

3

See p. 2 of the September 11, 2015 letter from Jeff Morris.

4

Also, as a reminder, the survey instrument was designed to be as simple and straightforward as possible to 

enhance the likelihood of participation by the indirect dischargers (who were under no obligation to participate). 

The instrument provided an opportunity for the respondents to provide further information on their operations or 
Page 4 of 7

As is discussed in the article “Silicones” in the Kirk-Othmer Encyclopedia of Chemical 

Technology, hydrolysis of dimethyldichlorosilane, itself obtained by reaction of elemental silicon 

and methyl chloride in the Rochow-Müller direct process, produces combinations of 

dimethylcyclosiloxanes (“cyclics”, primarily D4 and D5) and hydroxy-terminated linear 

dimethylsiloxanes (dimethyloligosiloxane-α,ω-diols or “linears”). Polycondensation of this 

combination of linears and cyclics, commonly known as dimethyl hydrolysate, produces higher 

molecular weight dimethyl siloxane polymers. Polycondensation/equilibration of dimethyl 

hydrolysate in the presence of other, functionalized siloxane oligomers or polymers produces 

siloxane copolymers. In both cases, due in part to siloxane equilibration reactions 

(redistribution), the product polysiloxanes will contain D4 and D5. 

In a manufacturing environment, equilibration of dimethyl hydrolysate coupled with distillation 

of the relatively volatile cyclics permits isolation of purified cyclics, notably D4. Ring-opening 

polymerization of D4 via anionic or cationic methods, especially in the presence of other, 

functionalized siloxanes, provides an alternative route to high molecular weight polysiloxanes. 

Notably, because of siloxane redistribution, the product polysiloxanes will contain D4 and D5. 

Alternatively, further equilibration of dimethyl hydrolysate coupled with stripping and recycling 

of cyclics permits production of relatively pure linear oligomers, seemingly circumventing the 

use of cyclics as a raw material. However, due to silicon redistribution, even polycondensation 

of “pure” linears in the “silanol” method will produce polysiloxanes containing D4 and D5

cyclics. As is discussed in the “Silicones” chapter of Ullmann’s Encyclopedia of Industrial 

Chemistry, cyclics still are formed at about two percent using the silanol method. 

In light of the above, the survey instrument used to confirm that the Indirect Discharge sites 

included in the Study Plan were receiving wastewater from a known D4 processor appropriately 

incorporated industry’s expert knowledge regarding siloxane chemistry. Each indirect 

discharger’s confirmation that it was processing one or more of the listed materials that are 

known to contain D4 further supports that the associated WWTP meets the site selection criteria 

set out in Appendix 2 to the ECA.5

b. EPA’s refusal to accept the Indirect Discharge WWTPs proposed in the 

Study Plan is based on the application of a criterion not prescribed in the 

ECA.

On page 2 of the September 11th Letter, EPA states that “[i]t is the facilities that process bulk D4 

... that need to be included in the monitoring program.” There is no such requirement in the 

ECA that the “industrial sites known to be a D4 processor or formulator” must also be processing 

 

to explain or to qualify any of their answers. If they believed that their site utilized a process or particular material 

that did not contain D4, then it would have been reasonable for them to note that in light of the obvious intent of 

the survey. 

5

As a reminder, the survey results were combined with an analysis of SIC and industry knowledge to substantiate 

the eligibility of the associated WWTP to be identified as an Indirect Discharge WWTP. 
Page 5 of 7

“bulk” D4. The term “bulk” does not appear anywhere in the ECA (including in Appendix 2 

which provides specific details on the required characteristics of the Indirect Discharge Sites), 

EPA cannot lawfully now insist that it is the threshold criterion for site selection.6

The site selection criteria spelled out in Appendix 2 to the ECA reflect the actual 

terms/conditions that were agreed upon by the parties through the formal negotiation process 

conducted in accordance with EPA’s ECA regulations.7 No party may unilaterally impose new 

conditions.8 We are unwilling to accept the attempted recasting or modification of the Indirect 

Discharge site selection criteria put forth by the Agency in the September 11, 2015 letter.

In contesting the Indirect Discharge WWTPs included in the Study Plan, the Agency also had 

argued that none of the indirect dischargers are D4 “processors” as defined by TSCA.9 As 

explained during the May 20, 2015 teleconference and in our June 5, 2015 letter, this position is 

refuted by the plain language of TSCA and EPA’s TSCA-implementing regulations as EPA has 

consistently defined the term process or processor to include “processing of any amount of a 

chemical substance or mixture.” 10 Historically, when the Agency has intended to narrow the 

universe of “processors” subject to a particular regulatory requirement, it has done so explicitly

in the associated rulemaking.11 We reject the notion the term “processor” should be construed to 

mean something different for purposes of the ECA than what it means throughout EPA’s TSCA 

regulations. If the Agency had desired for the term “processor” to mean something different or 

that only certain types of processors may qualify as indirect dischargers, then such language 

should have been proposed for inclusion in the ECA during the ECA negotiation. 

In its May 13, 2015, letter regarding the proposed Indirect Discharge sites, EPA had commented 

that “[b]ased on the survey results.... EPA is not able to substantiate that the processing of D4 or 

the formulation of D4–containing products is occurring at many of the industrial sites.” EPA 

then specifically identified the Gresham and Wichita WWTP sites as locations that “may not 

meet the conditions specified by the ECA.” 

Now, in the September 11, 2015 letter, EPA appears to fully reject the results of the survey and

all five of the proposed Indirect Discharge sites because, according to the Agency, “sampling 

results from the proposed WWTP sites would not inform an understanding of the environmental 

exposure associated with D4 releases from the processing and formulating sites that use D4 as a 

bulk material.”12

 

6

Notably, EPA does not mention the “bulk” qualifier in its March 9, 2015, April 2, 2015, or May 13, 2015 comments 

on the Study Plan. 

7

The ECA regulations appear in 40 C.F.R. part 790, subpart D.

8

As recognized in Section X of the ECA, any changes to the terms of the ECA must be made in accordance with the 

modification procedures set out in 40 C.F.R. § 790.68. 

9

This position was put forth in the Agency’s May 13, 2015 Letter and during its May 20, 2015 teleconference with 

SEHSC and the Signatory Companies. 

10 See SEHSC June 5, 2015, letter to the Agency for a detailed discussion of this issue. 

11 See 40 C.F.R. §§ 799.5055(b) and 799.1645(b) for examples in the TSCA section 4 test rule context. 

12 See p. 2 of the September 11, 2015 letter from Jeff Morris. 
Page 6 of 7

To bolster its argument (i.e., that either the term “processor” as used in the ECA must be 

interpreted to mean something different than it does elsewhere under TSCA or that the term 

“bulk” must be read into the ECA), the Agency points to a “Block Flow Diagram Template for 

Processors of D4 or D5 with On-Site and Off-Site Wastewater Treatment Plants” submitted by 

SEHSC in 2012. 

We note that the January 31, 2012 report, which was the source of the referenced block flow 

diagram, included multiple other block flow diagrams, including one for formulators. The 

purpose of those diagrams was not to define the terms of an ECA; rather it was to facilitate the 

identification of potential emission sources and the generation of generic conceptual site models. 

Moreover, there certainly was no agreement at the time of that report’s preparation and submittal 

regarding the site selection criteria or even the number of WWTPs to be included in a monitoring 

program. Indeed, the environmental monitoring proposal submitted by industry two months later 

did not include any Indirect Discharge WWTPs. Additionally, EPA had yet to publish an initial 

Federal Register announcing a public meeting to commence the ECA negotiation process.13 Any 

suggestion that the inclusion of the referenced diagram may be construed as offer or intent to 

agree upon a definition of processor that deviates from that established in EPA’s regulations or 

that only “bulk” processors would be included in the environmental monitoring program is 

inappropriate and unwarranted. 

Section V of the ECA states that “[t]he purpose of the Testing Program is to conduct 

environmental monitoring to characterize specified sources and pathways of release of D4 to the 

environment and resulting exposure of aquatic and sediment dwelling organisms to D4.” 

<emphasis added> It follows that one must look to the terms and conditions of the ECA to 

understand what sources and pathways are “specified,” not some other document or 

communication. Appendix 2 to the ECA sets out the criteria for Indirect Discharge WWTPs and 

there is no “bulk” qualifier included. 

III. Additional Items – Response to EPA’s Comments. 

Attachments 1 and 2 provide our responses to the other comments on the Study Plan and QAPP 

that were included with the September 11, 2015 letter. 

Section IX.A of the ECA states that “EPA shall approve the Study Plan at the same time QAPP 

is required if it meets the requirements of the ECA and 40 C.F.R. § 790.62(b).”14 This duty to 

approve is non-discretionary if the documents meet the cited requirements. Taking into account 

SEHSC’s prior submittals and the response to comments provided with this letter, the Agency 

has been provided with Study Plan and QAPP documents that meet the requirements of the ECA 

and the EPA regulations and guidance cited therein. 

 

13 That announcement was published in the May 24, 2012 Federal Register.

14 Section IX.A of the ECA states that “EPA shall approve the QAPP within 60 days receipt of the QAPP, if it meets 

the requirements of this ECA and is consistent with EPA guidance noted above.”
Page 7 of 7

SEHSC remains committed to generating data to support an environmental risk assessment for 

D4 that is consistent with sound science and comports with the industry’s commitment to 

environmental stewardship. This agreement is an extension of the silicone industry’s voluntary 

stewardship efforts to support greater scientific understanding of the health and environmental 

safety of siloxanes used in consumer and industrial applications. The reasons cited by the 

Agency for not promptly approving the Study Plan improperly rely upon requirements beyond 

those established in the ECA. Accordingly, we respectfully request that the Agency provide the 

requisite approval of the Study Plan and QAPP so that testing can move forward and data to 

support a risk assessment can be developed. 

We appreciate the Agency’s time and efforts on this matter and we look forward to continuing to 

work with EPA to complete this program. Please do not hesitate to contact me directly should 

you have any questions.

Sincerely,

Karluss Thomas

SEHSC Executive Director

cc: Michelle Long (EPA) 

Dow Corning Corporation

Evonik Corporation

Momentive Performance Materials USA, Inc.

Shin-Etsu Silicones of America, Inc.

Wacker Chemical Corporation

Keller and Heckman

Attachments (2)