Via Electronic Mail and Certified Mail

January 31, 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: Development of Environmental Monitoring Proposal for Certain Cyclic Siloxanes

Dear Dr. Doa:

On behalf of certain member companies1 of the Silicones Environmental, Health and Safety Council of 

North America (SEHSC)2

, we are writing to follow-up on our review and discussions of your September 

19, 2011 letter with attachments (September 19th Letter), which responded to the Draft Proposal for 

Ecotoxicity Testing and Environmental Monitoring with Certain Cyclic Siloxanes that we submitted to 

the U.S. Environmental Protection Agency (EPA) on April 29, 2011 (Initial Draft Proposal). As 

discussed more fully below, SEHSC has completed Conceptual Site Models (CSMs), which are now 

being used to develop a revised Enforceable Consent Agreement (ECA) proposal that we think will 

respond to EPA’s desires in a reasonable and practical manner. 

After receiving the September 19th Letter, SEHSC met with EPA staff on October 13 and October 27 

and by teleconference on November 10, 2011, to discuss and clarify EPA’s comments on the Initial 

Draft Proposal. During and since these discussions, SEHSC has been actively engaged in efforts to 

comprehensively address the issues EPA noted so as to inform the development of a revised 

environmental monitoring proposal. Attachment 1 to this letter provides a detailed description of the 

work performed, its implications, and the proposed conceptual elements of an environmental monitoring 

program. It also outlines the work currently underway, the completion of which will enable us to submit 

to EPA a refined ECA proposal. 

 1 Bluestar Silicones USA Corporation; Dow Corning Corporation; Evonik Goldschmidt Corporation; Momentive Performance 

Materials Inc.; Shin-Etsu Silicones of America, Inc.; and Wacker Chemical Corporation.

2 SEHSC is a not-for-profit trade association comprised of North American silicone chemical 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 focus of SEHSC is to coordinate scientific research on health, safety and environmental 

issues involving silicones.
Maria J. Doa, Ph.D.

US Environmental Protection Agency

January 31, 2012

Page 2 of 3

As documented in Attachments 1 and 2, SEHSC member companies have expended considerable 

resources to generate D4 and D5 facility release data for each of thirteen sites.3

 SEHSC engaged 

Environmental Resource Management (ERM), an environmental consulting firm (Consultant), to 

aggregate these data and compile summary statistics and mass balances by facility type (i.e., 

manufacturer, formulator, or processor). The collection and aggregation of these data represent a 

substantial effort over a short period of time and, more importantly, provide valuable new information 

regarding the release profile of representative D4 and D5 manufacturing, processing, and formulating

(MPF) facilities. 

The Consultant used the aggregated facility release data to develop a generic CSM for Member 

Company D4 and D5 MPF facilities. In addition, the Consultant prepared a generic CSM for Municipal 

Wastewater Treatment Plants (WWTPs). Together, these CSMs provide for a reasonable 

understanding of D4 and D5 releases from MPF facilities and WWTPs, the resulting exposure pathways, 

and potential receptors. The CSMs demonstrate that the appropriate conceptual elements of a D4 and 

D5 environmental monitoring program would include a focus on the aquatic environment and could 

include releases from WWTP as well as those from D4 and D5 MPF facilities that discharge effluent 

directly to surface waters. 

Importantly, the Global Silicones Industry has an ongoing environmental stewardship program to 

monitor the presence of D4 and D5 in a number of international locations, including in the United States. 

This program encompasses the monitoring of D4 and D5 in the influent, effluent, and sludge of WWTPs

and the monitoring of D4 and D5 in surface sediment and aquatic biota potentially impacted by releases 

from nearby facilities. Based on the CSMs, it appears that augmenting this voluntary program by 

extending key elements to a domestic U.S. monitoring program to include additional municipal WWTP 

sites and SEHSC Member Company facilities that directly discharge effluent to surface waters could 

provide a principled and scientifically sound means to generate a robust dataset for assessing the 

potential environmental impacts of these substances. 

SEHSC is continuing to work with a Consultant to develop the substantive elements of a revised ECA 

proposal that is both grounded in sound science and that takes into account the existing data and data 

collection efforts relating to these substances. Additional tasks that are on-going include the 

development of the scientific rationale for augmenting the international environmental stewardship 

program by extending key elements to a domestic U.S. monitoring program with additional sites, the 

identification of specific WWTP sites in the U.S. for monitoring based on the CSM and additional 

modeling, and confirmation of end points, number of samples, and frequency/duration of sampling for 

monitoring locations. The completion of these tasks will enable us to provide EPA with a revised ECA 

Proposal that contains a level of specificity which is intended to not only help facilitate EPA’s 

consideration of the proposal, but also provide the participating Member Companies with an 

appropriate level of certainty regarding the potential scope of the program which they will be agreeing 

to propose. 

 3 Our Initial Draft Proposal identified fourteen sites under the direct control of participating SEHSC member companies that 

were engaged in D4/D5 manufacturing, processing, or formulating activities. Upon further review, it has been determined 

that one of those sites should not have been included as it does not manufacture, process, or formulate with D4 or D5. A 

revised list is provided in Attachment 3 which also reflects updates to the “facility description” for certain locations based 

on revised information concerning D4, D5 activities at those sites. 
Maria J. Doa, Ph.D.

US Environmental Protection Agency

January 31, 2012

Page 3 of 3

We are working to complete these tasks as quickly as possible and will keep you informed of our 

progress. In the meantime, we welcome the opportunity to meet with you and your staff to discuss the 

work performed to date and our proposed approach. We will follow up with you in this regard. Should 

you have any questions or concerns, please do not hesitate to contact me.

Sincerely,

Karluss Thomas

Executive Director

Enclosures

Attachment 1 – Description of Work Performed, Implications, On-going Work

Attachment 2 – D4 and D5 Conceptual Site Models and Mass Balance Report 

Attachment 3 – Table of SEHSC Member Company D4/D5 Manufacturing, Processing, and Formulating 

 Facilities in the U.S. 
Attachment 1

Description of Work Performed, Implications, On-going Work
Silicones Environmental, Health and Safety Council

January 31, 2012

ATTACHMENT 1

In communications to the Silicones Environmental, Health and Safety Council (SEHSC), 

including in the September 19, 2011 letter with attachment (September 19th Letter), the U.S. 

Environmental Protection Agency (EPA) has indicated that the purpose of a D4 and D5

environmental monitoring program would be to develop a better understanding of the sources of 

and pathways to the potential environmental concentrations of D4/D5 in environmental media 

and biota associated with industrial releases from manufacturing, processing, formulating (MPF) 

and high volume industrial or commercial end users of D4 and D5. In the September 19th Letter, 

EPA outlined a four-phase approach to such a program, which included the development of 

Conceptual Site Models (CSMs) at the outset for MPF facilities and municipal wastewater 

treatment plants (WWTPs). EPA indicated that these CSMs would be used to determine 

appropriate media types and sampling locations and to otherwise inform the preparation of a 

detailed sampling plan. 

Bearing this in mind, SEHSC member companies have been actively engaged over the past 

several months to develop a revised proposal that appropriately addresses EPA’s concerns in 

light of available information. This document summarizes the work SEHSC member companies 

have performed with respect to the design and development of a revised environmental 

monitoring proposal for consideration by EPA. In particular, it describes the specific tasks 

completed and their implications, proposed conceptual elements/approach for a D4/D5

environmental monitoring program, and on-going work. 

Description of Work Performed and Implications

1. Member Company Survey - Data Collection on Material Throughput and Releases at MPF 

Sites.

To facilitate the preparation of CSMs for MPF facilities, six SEHSC member companies 

participated in a survey regarding D4 and D5 throughput and estimated releases at their D4/D5

MPF facilities. A list of participating companies and facilities is provided in Attachment 3. 

Participating companies provided worksheets containing confidential business information (CBI) 

on a total of thirteen MPF facilities to SEHSC for processing (due to CBI concerns worksheets 

submitted by each company were not shared with the other member companies). Respondents 
Silicones Environmental, Health and Safety Council

January 31, 2012

provided information on D4/D5 input and output streams for each site using a standard template 

with reference to a generic block flow diagram. For sites engaged in multiple activities (e.g., 

both processing and formulating), input/outputs with respect to a particular activity were 

reported separately, as appropriate. 

Member companies committed significant internal and external resources to generate the data 

needed to participate in this survey in the given timeline. This considerable effort resulted in the 

collection of detailed information on two manufacturing, seven formulating, and nine processing 

facilities (corresponding to the D4/D5 MPF facilities under the direct control of the participating 

SEHSC member companies). As discussed further below, SEHSC engaged Environmental 

Resources Management (ERM), an environmental consulting firm (Consultant), to process and 

analyze these data. 

2. Data Analysis - Aggregation, Preparation of Summary Statistics, Mass Balances, and CSMs

SEHSC’s Consultant reviewed the facility worksheets supplied by the SEHSC member 

companies, aggregated the data, and prepared summary statistics on each input/output stream. 

Mass balances and corresponding block flow diagrams showing representative input/output 

amounts were prepared for each facility-type for which sufficient data were available. No mass 

balances or summary statistics are provided for D4/D5 manufacturing or D4 formulating due to 

confidentiality issues as fewer than three companies could provide relevant data. However, to 

provide EPA with a profile of manufacturing sites, the two companies engaged in D4/D5

manufacturing each intend to provide confidential facility input/output stream data to EPA under 

separate cover so that these highly sensitive data may be accorded appropriate CBI protection. 

The Consultant’s Report, which contains a description and analysis of the data and relevant 

tables and figures, is provided in Attachment 2. 

The Consultant also used the data obtained in the member company survey and available fate 

and transport information for D4 and D5 to prepare a generic CSM for human and ecological 

receptors for D4/D5 MPF facilities, which is shown in Figure 6 of Attachment 2. The Consultant 

determined that a single, generic CSM for human and ecological receptors would appropriately 

represent both D4 and D5 and all facility types. A complete description of the CSM and its 

underlying scientific basis is provided in Section 3.0 of the Consultant’s Report in Attachment 2.
Silicones Environmental, Health and Safety Council

January 31, 2012

As described in the Consultant’s Report, although a wide range of potential pathways for D4 and 

D5 are depicted in the CSM, the only exposure pathways deemed potentially complete for D4

and D5 (i.e., pathways that lead to a reasonable expectation of potential exposure to humans or 

the environment) are: 

• inhalation exposure resulting from dispersion in air (this pathway applies only to human 

receptors, because ecological receptors are not typically evaluated for inhalation 

exposure risk); and 

• exposures via sediment, including direct exposure for bottom-dwelling biota and indirect 

exposure via the food chain to ecological receptors.

The Consultant also prepared a generic CSM for human and ecological receptors for municipal 

WWTPs based on a consideration of types of units, releases, and site characteristics associated 

with municipal WWTPs. This CSM is shown in Figure 11 of Attachment 2. A complete 

description of the generic CSM for municipal WWTPs and its underlying scientific basis is 

provided in Section 5.0 of the Consultant’s Report in Attachment 2.

The generic CSM for municipal WWTPs also shows a wide range of potential pathways for D4

and D5, but only air for human receptors and sediment for ecological receptors are considered 

to be complete pathways based on the characteristics of the materials and available 

information.

As highlighted below, these findings are significant with respect to the design of an 

environmental monitoring program. 

Conceptual Elements of Environmental Monitoring Program

Based on an evaluation of the MPF and municipal WWTP CSMs, an appropriate focus of an 

environmental monitoring program would be on relevant media for MPF sites that directly 

discharge effluent to surface waters (4 sites in total, as show in Attachment 3) and on municipal 

WWTPs whose effluent would reflect inputs from industrial sites that process or formulate with 

D4 or D5 and/or dispersive (consumer) uses (number of sites to be determined, as noted in the 

discussion of On-going Activities, below). 
Silicones Environmental, Health and Safety Council

January 31, 2012

Final design of the proposed environmental monitoring program will entail a careful evaluation of 

the CSMs. Pathways of migration are clearly diagrammed in the CSMs for human and 

ecological receptors and will form the basis for selection of media sampling types and locations 

at each facility identified for monitoring. In addition, data available as a part of the on-going 

global monitoring program the Silicone Industry originally initiated in the 1990s on D4 in effluents 

and a robust program initiated in 2009 to understand the actual fate and effects of cVMS in the 

environment will help inform the basis of a proposed monitoring plan. 

With respect to the air pathway, although hypothetically a complete pathway, it is not relevant to 

a proposed environmental monitoring program. Inhalation exposure resulting from dispersion in 

air applies only to human receptors as ecological receptors are not typically evaluated for 

inhalation exposure risk. Also, the environmental fate and transport in air of volatile 

methylsiloxanes such as D4, and D5 have been thoroughly investigated in modeling 

assessments, and laboratory and field studies. The results of those studies are summarized 

below:

• Volatile methylsiloxanes such as D4 and D5 have a unique combination of 

physicochemical properties: relatively high volatility (like small alkanes), high air/water 

partition coefficients, medium to low octanol/air partition coefficients and relatively short 

half-lives (6~10 days) in air. Based on modeling calculations, once released to the 

environment, the majority of D4 and D5 will be distributed in the air; greater than > 98% of 

all the emitted methylsiloxanes will be degraded in the atmosphere; >90% degradation 

occurred in the atmosphere over the source regions (Xu and Wania, 2011).

• Based on an assessment with the OECD overall persistence and LRTP screening tool (v 

2.1) and the GloboPOP model, D4 and D5 can travel a long distance in air, but only a 

small fraction (< 9 %) of the emitted total may be circulated in the air outside of the 

source regions (Xu and Wania, 2011). The airborne D4 and D5 tend to stay in the air and 

exhibit a very small potential to deposit back to the ground or waterways (Xu and Wania, 

2011). 

• Ambient air monitoring data generally agree with the above modeling assessments, 

including the concentrations measured in rural and remote regions (McLachlan et al, 

2010; Genualdi et al., 2010). 

• The existing monitoring data of the surface media in remote regions are also consistent 

with the lack of deposition of volatile methylsiloxanes as summarized in a recent 
Silicones Environmental, Health and Safety Council

January 31, 2012

document by Environment Canada (Environment Canada, 2011, D5 Board of Review 

“Ringtail” Document 232). For example, D4 and D5 can be easily detected in sediment 

near the points of release, but D4 and D5 above the detection limits cannot be found in 

remote sediments, including the samples from the cold arctic regions (Evenset, 2009; 

Campbell, 2010). For biota, D4 and D5 were again not detectable in most fish samples 

collected in the remote regions that have no local route of exposure (Warner et al, 2010). 

The above information shows that, although D4 and D5 are released to air from both MPF 

facilities and Municipal WWTPs, the deposition of airborne D4 and D5 to surface media is 

estimated to be very small due to the unique combination of physicochemical properties of 

these chemicals. As concluded by an Independent Expert Scientific Panel (Canadian D5 Board 

of Review) “an important aspect of the environmental fate of Siloxane D5 is that the 

compartment into which it is most released and most likely to occur is also the compartment 

where it undergoes the most rapid rate of transformation.” For these reasons, the release to air 

will not lead to exposure of ecological receptors and, therefore, it is not anticipated to be part of 

a revised proposed environmental monitoring program. 

On-Going Activities

SEHSC member companies are engaged in a number of on-going activities designed to inform 

the preparation of a revised D4/D5 environmental monitoring proposal. These activities include 

working with a Consultant to identify specific WWTP sites in the U.S. for monitoring based on 

the CSM and additional modeling analyses; confirmation of end points, number of samples, and 

frequency/duration of sampling for monitoring locations; and the development of scientific 

rationale for augmenting the Silicones Industry international environmental stewardship program 

by extending key elements to a domestic U.S. monitoring program with additional sites. 

1. Identification of Specific Sampling Locations, Media 

SEHSC’s Consultant has also been tasked with assisting in the development of a potential 

D4/D5 environmental monitoring program through the identification of specific municipal WWTPs 

for inclusion in the program based on a consideration of relevant key variables, potentially 

including location of indirect discharge MPF facilities, population served by the WWTP, and 
Silicones Environmental, Health and Safety Council

January 31, 2012

plant characteristics (e.g., treatment type, size, rural vs. urban, watershed and geographic 

location in the U.S., etc.). This work is on-going. 

Other parameters will also be considered in the final selection of sites after evaluation of the 

relevant data, including WWTP monitoring programs/data for D4 and D5 that are ongoing. For 

example, WWTP data have already been reported by Environment Canada (EC) and the 

Oregon Department of Environmental Quality (OR DEQ). Both EC and OR DEQ have included 

a variety of WWTP/POTW sites that take into consideration both dispersive uses from 

populations of different sizes and/or industrial discharge. In Canada, the dataset demonstrates 

a high removal efficiency by all WWTP types, with the possible exception of non-aerated 

lagoons. All types of WWTPs (tertiary, secondary, and aerated lagoons) have D4/D5 removal 

efficiencies in excess of 97%. The efficiency of non-aerated primary treatment lagoons was 

estimated at 92%. The OR DEQ initiated a WWTP monitoring program in 2010 which required 

52 major facilities to analyze their effluent for D4 and D5. Analysis conducted to date found that 

D4 and D5 levels were below the 7-16 ppb analytical levels of quantitation (LOQs) in all WWTP 

effluent evaluated.

A determination of number of sites, frequency/duration of sampling, media, etc. will be provided 

in the revised environmental monitoring proposal. 

2. Augmenting Global Silicone Industry International Environmental Monitoring Program.

The Global Silicones Industry has an ongoing international environmental stewardship program 

to monitor the presence of D4 and D5 in a number of international locations -- including one site 

in the U.S. The purpose of this program is to enhance the understanding of the potential 

contribution of D4 and D5 to the environment via the discharge of effluent into surface water, 

which can result in exposure through sediment, including direct exposure for bottom-dwelling 

biota and indirect exposure via the food chain to ecological receptors. 

Based on the CSMs, it appears that augmenting this voluntary program by extending key 

elements to a domestic U.S. monitoring program to include additional municipal WWTP sites 

and SEHSC Member Company facilities that directly discharge effluent to surface waters could 

provide a principled and scientifically sound means to generate a robust dataset for assessing 

the potential environmental impacts of these substances.
Silicones Environmental, Health and Safety Council

January 31, 2012

For your reference, additional background on the international environmental stewardship 

program is provided below. The program includes two key elements:

• The first element is the determination of representative concentrations of D4 and D5

in the wastewater stream (influent, effluent, and sludge) of municipal WWTPs. The 

data will be used to estimate mass loadings of D4 and D5

• The second element is long-term monitoring for D4 and D5 in surface sediment and 

aquatic biota (marker fish and benthic species) at 4 sites globally with annual sample 

collection to assess temporal trends in D4 and D5 concentrations in sediments and 

biota near impacted areas. The goal of this project is to determine if concentrations 

of D4 and D5 in sediment and aquatic biota are stable. 

to the local aquatic 

environment and to detect any temporal trends associated with the mass loading. 

Detailed project charters are in place for both of these key elements and are available if desired. 

The proposed study areas – as well as previously studied locations across the globe -- including 

Oslo (Norway), Tokyo Bay (Japan), Toronto, Ontario (Canada), and St. Paul, Minnesota (USA), 

represent a broad cross section of environmental conditions. 

With respect to the first element, analytical method development is completed for biosolids and 

is near complete for influent/effluent (expected S1 2012). Adaptation of the Simple Treat model 

is underway to handle all WWTP types and will be used to model the behavior of D4 and D5 in 

various types of WWTPs. 

With respect to the long-term monitoring element, the results of several modeling projects 

suggest that measured concentrations in air, water, soils, and sediments, as well as in 

organisms, will reflect pseudo-steady-state (concentrations will change seasonally but are 

largely a consequence of the current rate of emission). This was recently confirmed by an 

independent Expert Scientific Panel (Canadian D5 Board of Review Report) as the Expert Panel 

concluded “The rate of accumulation of Siloxane D5 in air, water, soils, and sediments, as well 

as in organisms, is determined by its rate of release to the environment and, once there, its 

rates of movement to other compartments of the environment (dissipation) and transformation. 

Because Siloxane D5 has been used in commercial and industrial applications for a relatively 
Silicones Environmental, Health and Safety Council

January 31, 2012

long time – more than 30 years – and, given its rates of dissipation and transformation in the 

environment, current concentrations of Siloxane D5 are at a quasi-steady-state.”

Similarly, this means that measured concentrations in the top few centimeters of sediment are 

likely to reflect a pseudo-steady-state as well, particularly in systems with high rates of net 

sedimentation like Lake Pepin (30 mm per year) and the coastal sediments of the Inner 

Oslofjord (up to 9 mm per year). In systems with a lower rate of sediment deposition, such as 

the deep basins of Lake Ontario, the sediment would probably need to be collected from the top 

1-2 cm to ensure that concentrations reflect the average rate of emission in the last 10 years. 

The predicted behavior of D4 and D5 in three different aquatic systems has been investigated 

using an established steady state model (QWASI). The three systems examined were the 

Inner Oslofjord (Norway), Lake Ontario (North American Great Lakes) and Lake Pepin (a natural 

shallow lake on the Mississippi river between Minnesota and Wisconsin, down-stream of 

Minneapolis-St Paul. In all cases, models predict that concentrations in the top 5 cm of 

sediment reach steady state concentration levels within 8 years. It follows that concentrations 

measured in the surface layer of sediment will be reflective of current emission levels, since 

emissions of D4 and D5 have not changed markedly in the last 10 to 15 years globally. As 

noted above, the goal of the project is to confirm whether concentrations of D4 and D5 in 

surface sediment and aquatic biota are stable or changing (following a decreasing or increasing 

trend). 

This ongoing effort described above, combined with augmenting this program by extending key 

elements to a domestic U.S. monitoring program to include additional municipal WWTPs in the 

U.S. and the monitoring of releases of D4 and D5 from member company facilities with direct 

discharges, would provide a robust dataset for understanding the potential contribution of D4

and D5 to the environment via the discharge of effluent into surface water. 

The details of sampling (e.g., minimum number of samples per location) and an analysis plan 

for each specific site would need to be developed for inclusion in a revised Enforceable Consent 

Agreement (ECA)-related monitoring plan. However, a significant amount of work has already 

been completed on analytical methods and QA/QC for environmental monitoring of cyclic 

siloxanes (Durham et al., 2009a and 2009b).
Silicones Environmental, Health and Safety Council

January 31, 2012

References

Canadian D5 Board of Review Report; Report of the Siloxane D5 Board of Review (PDF; 

817KB) http://cdr-siloxaned5-bor.ca/default.asp?lang=En&n=60053180-1

Campbell, R. 2010. A collaborative assessment of cyclic volatile methylsiloxanes (D4, D5, D6) 

concentrations in the Norwegian Environment. Final Report to Centre Europeen des 

Silicones(CES), European Chemical Industrial Council (CEFIC), Dow Corning HES Study No. 

11061-108.

Canadian D5 Board of Review Report; Report of the Siloxane D5 Board of Review (PDF; 

817KB) http://cdr-siloxaned5-bor.ca/default.asp?lang=En&n=60053180-1

Durham, J.A., Huff, D.W, McNett, D.A., Powell, D.E., Gerhards, R, and Boehmer, T. 2009. 

Development of a Robust Quality Control Program for Environmental

Monitoring Studies with Cyclic Siloxanes, Poster presented at SETAC North America, 30th

Annual Meeting, 19-23 November 2009, New Orleans, Louisiana.

Durham, J.A., Huff, D.W, McNett, D.A., Powell, D.E. 2009. Trace analytical method 

development enhanced by the use of 14C-radiolabelled isotopes of octamethycyclotetrasiloxane 

(D4), decamethylcyclopentasiloxane (D5), and dodecamethylcyclohexasiloxane (D6), Poster 

presented at SETAC Europe, 19th Annual Meeting, 31 May – 4 June 2009, Göteborg, Sweden.

Environmental Canada, 2011, Ecotoxicity and environmental occurrence of 

octamethylcyclotetrasiloxane (D4), decamethylpentasiloxane (D5), and 

dodecamethylcyclohexasiloxane (D6)-State of the Science. D5 Board of Review “Ringtail” 

Document 232. 

Evenset, A.; Leknes, H.; Christensen, G.; Warner, N. A.; Remberger, M.; Gabrielsen, G. W. 

2009. Screening of new contaminants in samples from the Norwegian Arctic. SFT Report 

1049/2009 (TA-2510/2009). Oslo (NO): Norwegian Pollution Control Authority (SFT), Akvaplanniva, Norwegian Polar Institute and Norwegian Institute for Air research (NILU).

Genualdi, S., Harner, T. Cheng, Y., MacLeod, M., Hansen, K. M., van Egmond, R.; Shoeib, M., 

Lee, S. C., 2011. Global distribution of linear and cyclic volatile methyl siloxanes in air. Environ. 

Sci. Technol. 45, 3349-3354.

McLachlan, M. S., Kierkegaard, A., Hansen, K. M., Van Egmond, R., Christensen, J. H., Skjøth, 

C. A., 2010. Concentrations and fate of decamethylcyclopentasiloxane (D5) in the atmosphere. 

Environ. Sci. Technol. 2010, 44, 5365-5370.

Warner, N. A.; Evenset, A.; Christensen, G.; Gabrielsen, G. W.; Borga, K.; Leknes, H. 2010. 

Volatile siloxanes in the European Arctic: Assessment of the sources and spatial distribution. 

Environ. Sci. Tecnol. 44, 7705-7710.

Xu, S.; Wania, F. 2011. Chemical Fate, Latitudinal Distribution and Long-Range Transport of 

Cyclic Volatile Methylsiloxanes in the Global Environment: A Modeling Assessment. 

Chemosphere. 2011 (In Press). 
Attachment 2

D4 and D5 Conceptual Site Models and Mass Balance Report
FINAL 

Delivering sustainable solutions in a more competitive world

D4 and D5 Conceptual Site 

Models and Mass Balance 

Report 

Silicones Environmental, Health and Safety Council 

Herndon, VA 20171 

January 2012 

www.erm.com 
FINAL 

Silicones Environmental, Health and Safety Council 

D4 and D5 Conceptual Site 

Models and Mass Balance 

Report 

January 2012 

ERM Project No. 0151161 

Salvatore T. Giolando, Ph.D. Partner-in-Charge 

Steve Peterson, Ph.D., Technical Director 

Elsie F. Millano, Ph.D., P.E., Project Manager

Environmental Resources Management 

1701 Golf Road, Suite 1-1000 

Rolling Meadows, IL 60008 

www.erm.com 
FINAL 

ERM iii January 2012

TABLE OF CONTENTS 

EXECUTIVE SUMMARY.............................................................................................VII

1.0 INTRODUCTION.................................................................................................1

2.0 FATE AND TRANSPORT INFORMATION ....................................................3

3.0 CONCEPTUAL SITE MODEL FOR D4 AND D5 INDUSTRIES....................6

3.1 GENERIC BLOCK FLOW DIAGRAM TEMPLATES .........................6

3.1.1 Manufacturer Block Flow Diagram Description.......................6

3.1.2 Formulator Block Flow Diagram Description...........................7

3.1.3 Processor Block Flow Diagrams Description ............................8

3.1.4 Basis for a Single CSM for All Types of Facilities ....................9

3.2 GENERIC D4 AND D5 INDUSTRIAL CSM FOR HUMAN AND 

ECOLOGICAL RECEPTORS .................................................................9

3.2.1 Procedures..................................................................................9

3.2.2 Air Pathways ...........................................................................10

3.2.3 Surface Soil ..............................................................................11

3.2.4 Surface Water ..........................................................................11

3.2.5 Sediments.................................................................................12

3.2.6 Landfills to Air and Ground Water.........................................12

3.2.7 Summary..................................................................................12

4.0 MASS BALANCE DATA AGGREGATION....................................................13

4.1 PROCEDURES........................................................................................13

4.2 MASS BALANCE DATA AGGREGATION RESULTS .....................14

4.2.1 Manufacturers Data Observations..........................................14

4.2.2 Formulators Data Aggregation Observations.........................14

4.2.3 Processors Data Aggregation Observations............................15

5.0 GENERIC POTW CSM ......................................................................................17

5.1 GENERAL TREATMENT REQUIREMENTS.....................................17

5.2 POTW POTENTIAL TREATMENT TECHNOLOGIES....................17

5.3 POTENTIAL EFFECTS OF POTW TREATMENT 

TECHNOLOGIES ON THE FATE AND TRANSPORT OF D4 OR 

D5 ...............................................................................................................18

5.4 DESCRIPTION OF THE “TYPICAL” POTW ....................................19
FINAL 

ERM iv January 2012

5.5 GENERIC CSM FOR HUMAN AND ECOLOGICAL RECEPTORS 

FOR POTWS RECEIVING WASTEWATER CONTAINING D4 OR 

D5 ...............................................................................................................21

6.0 CONCLUSIONS..................................................................................................22

LIST OF TABLES 

Table 1 Member Company Facilities that Reported Data 

Table 2 Summary of Data Aggregation before Mass Balance for 

Formulators 

Table 3 Mass Balance for Formulators of D5

Table 4 Summary of Data Aggregation before Mass Balance for 

 Processors 

Table 5 Mass Balance for Processors 

Table 6 Potential Technologies and Disposal Options for Publicly 

Owned Treatment Works 

LIST OF FIGURES 

Figure 1 Block Flow Diagram Template for Manufacturers of D4 or 

D5

Figure 2 Block Flow Diagram Template for Formulators of D4 or D5

Figure 3 Block Flow Diagram Template for Processors of D4 or D5

with On-site Wastewater Treatment Plant 

Figure 4 Block Flow Diagram Template for Processors of D4 or D5

without On-site Wastewater Treatment Plant 

Figure 5 Block Flow Diagram Template for Processors of D4 or D5

with On-site and Off-site Wastewater Treatment Plants 

Figure 6 Generic D4 and D5 Industrial Conceptual Site Model for 

Human and Ecological Receptors 

Figure 7 Mass Balance for Formulators of D5

Figure 8 Mass Balance for Processors of D4
FINAL 

ERM v January 2012

Figure 9 Mass Balance for Processors of D5

Figure 10 Generic Block Flow Diagram for POTWs Receiving 

Wastewater Containing D4 or D5

Figure 11 Generic Conceptual Site Model for Human and Ecological 

Receptors for POTWs Receiving Wastewater Containing D4

or D5
FINAL 

ERM vi January 2012

LIST OF ACRONYMS 

CSM Conceptual Site Model 

ERM Environmental Resources Management, Inc. 

D4 Octamethylcyclotetrasiloxane 

D5 Decamethylcyclopentasiloxane 

NESHAP National Emission Standards for Hazardous Air 

Pollutants 

NPDES National Pollutant Discharge Elimination System 

OSHA Occupational Safety and Health Administration 

POTW Publicly Owned Treatment Works 

SEHSC Silicones Environmental, Health and Safety Council 

USEPA United States Environmental Protection Agency 

WEF Water Environment Federation 

WWTP Wastewater Treatment Plant 
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ERM vii January 2012

EXECUTIVE SUMMARY 

Environmental Resources Management (ERM) was retained by the 

Silicones Environmental Health and Safety Council (SEHSC) to evaluate 

facility emissions and throughput data provided by six companies that are 

members of SEHSC (Member Companies) to develop two work products: 

 Generic aggregate Conceptual Site Models (CSMs) for facilities in the 

United States, including manufacturers, formulators, and processors 

of D4 and D5; and 

 Mass balances for formulators of D5 and for processors of D4 and D5. 

No mass balances for manufacturers of D4 and D5 and formulators of 

D4 are provided due to business confidentiality concerns (fewer than 

three Member Companies provided data). 

ERM developed CSMs based on standard practices for risk assessment.1,2,3 

In addition, the SEHSC tasked ERM with developing a generic CSM for 

publicly owned treatment works (POTWs) that receive wastewater 

containing D4 and/or D5 (the “POTW CSM”). A generic block diagram 

was prepared for a typical mid- to small-size POTW, with the assumption 

that it had only (1) primary and secondary treatment (activated sludge) 

and effluent chlorination for the liquid waste before discharge to a surface 

water body, and blending and storage, anaerobic digestion, and storage 

for the sludge produced during primary and secondary treatment 

(“biosolids”), followed by beneficial use of the biosolids as a fertilizer or 

soil amendment. 

Based on the evaluation presented in this report, ERM concluded the 

following for the industrial facilities: 

 Aggregation of all facilities for the generic conceptual site model with 

arithmetic weighted averages of the emissions for the different types 

of facilities provide a useful summary of the potential fate, transport, 

and exposure pathways for these substances in the environment. 

 

1 USEPA (2001). Risk Assessment Technical Background Document for the Paint and Coatings Hazardous Waste 

Listing Determination. 2 USEPA (1996). Attachment A in Soil Screening Guidance: User’s Guide, EPA/540/R-96/018. 

3 USEPA (1988). Guidance for Conducting Remedial Investigations and Feasibility Studies under CERCLA, 

EPA/540/G-89/004. 
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ERM viii January 2012

 The greatest emissions of D4 and D5 are those to air, given that the 

solid waste or waste from operation streams sent off-site for disposal 

are typically thermally treated, which treatment would destroy most, 

if not all, D4 and D5 in those waste streams.. 

After assessing the chemical and physical properties of D4 and D5 and the 

potential sources and pathways of exposure to human and ecological 

receptors, ERM concluded that the following two pathways were 

potentially complete for both the generic industrial facility and the generic 

POTW: 

 Inhalation exposure resulting from dispersion in air (this pathway 

applies only to human receptors, because ecological receptors are not 

typically evaluated for inhalation exposure risk). 

 Exposures via sediment, including direct exposure for bottomdwelling biota and indirect exposure via the food chain to ecological 

receptors. 
FINAL 

ERM 1 January 2012

1.0 INTRODUCTION 

Octamethylcyclotetrasiloxane (D4) and decamethylcyclopentasiloxane (D5) 

are chemical products from the broader family of polydimethylsiloxanes 

(PDMSs) that have a wide range of industrial and consumer applications 

in the United States and internationally. Both of these substances are 

manufactured, formulated and/or processed at a number of sites in the 

United States. The Silicones Environmental, Health and Safety Council 

(SEHSC) retained Environmental Resources Management, Inc. (ERM) to 

prepare the following work products: 

 The generic conceptual site model (CSM) and mass balances 

presented herein for industrial facilities; and 

 A block flow diagram and CSM for publicly owned treatment works 

(POTWs) for use in the evaluation of emissions from POTWs 

receiving D4 and/or D5. 

To complete the industrial CSM, ERM was tasked with reviewing 

Business Confidential worksheets provided by six of the SEHSC member 

companies with input and output data for three types of facilities 

(manufacturers4, formulators5, and processors6). Data were received from 

six Member Companies regarding 13 distinct facilities, including two sites 

engaged in manufacturing, seven in formulating, and nine in processing 

activities -- see Table 1 (some facilities engaged in more than one activity). 

It is important to note that D4 and D5 are sold to numerous other 

downstream formulators and processors in significant quantities. This 

report does not include data from those downstream customers. 

The remainder of this report is organized as follows: 

 Section 2.0: Presents relevant chemical, physical, and environmental 

fate and transport properties of D4 and D5; 

 Section 3.0: Describes the development and conclusions of the CSM 

work, including the industrial block flow diagrams used to develop 

the industrial CSM, the industrial CSM itself, and the rationale for 

selection of complete pathways; 

 

4 Facilities that manufacture D4 and/or D5 on-site. 

5 Facilities that mix or blend D4 and/or D5 to create products. 6 Facilities that react D4 and/or D5 to create other substances. 
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ERM 2 January 2012

 Section 4.0: Presents the mass balances calculated from the input and 

output data provided by the Member Companies. Input and output 

streams data provided by the SEHSC Member Companies are not 

included in this report to avoid Business Confidentiality and 

Antitrust issues; 

 Section 5.0: Discusses the POTW block flow diagram and CSM; and 

 Section 6.0: Summarizes the conclusions of the work. 
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ERM 3 January 2012

2.0 FATE AND TRANSPORT INFORMATION 

Both D4 and D5 have been extensively evaluated for potential 

environmental effects on both humans and ecological receptors. The 

physico-chemical and environmental fate properties listed below indicate 

that both substances are sparingly soluble in water, adsorb strongly to 

solid particles in the presence of organic carbon, volatilize rapidly and 

hydrolyze slowly at neutral pH but much faster at the lower and higher 

pH values more commonly found in the environment. Based on data 

contained in the GEMS/WATER databank, most average annual pH 

values are between 6.5 and 8.3, with a global median pH of 7.7.7

Substance 

Information D4 Source D5 Source 

Physico-Chemical Properties 

Solubility 0.056 mg/L at 23°C 0.017 mg/L at 23-25°C 

Log Kow (n-octanol-water 

partition coefficient) 6.49 8.03 

Vapor pressure 132 Pa at 25°C 33.2 Pa at 25°C 

Henry’s Law Constant 

(Pa m3 / mol) 1,214,000 at 25°C 

UK D4

Report8

3,342,000 at 25°C 

UK D5 Report9

Environmental Fate Properties 

(pH 4) 1.8 h at 25°C (pH 5) 96 h at 25°C 

(pH 7) 144 h at 25°C (pH 7) 1704 h at 25°C 

Hydrolysis half-lives 

(pH 9) 1 h at 25°C 

UK D4

Report (pH 9) 24 h at 25°C 

UK D5 Report 

Log Koc (organic carbonwater partition coefficient) 4.22 Miller & 

Kozerski, 

200710

5.17 Canada D5 

Review11 and 

Durhan and 

Kozerski, 200712

Log KOA (n-octanol-air 

partition coefficient) 

4.34 SEHSC, 

200813

5.06 __14

 

7 United Nations Environment Programme, Acidification of Surface Waters, available at 

http://www.gemswater.org/atlas-gwq/acid-e.html. 8 Environment Agency (2009a). Environmental Risk Assessment Report: Octamethylcyclotetrasiloxane, 

Bristol, UK, April 2009. 

9 Environment Agency (2009b). Environmental Risk Assessment Report: Decamethylcyclopentasiloxane, 

Bristol, UK, April 2009 10 Miller, J.A. and Kozerski, G.E. (2007). Soil-Water Distribution of Octamethylcyclotetrasiloxane (D4) Using 

a Batch Equilibrium Method. Report to CES. Dow Corning Report No.: 2007-I0000-58266. 11 Siloxane D5 Board of Review (2011). Report of the Board of Review for D5, Canada, October 20, 2011. 12 Durham, J., Kozerski, G.E., Miller, J.A., and Sushynski, C.M. (2007). Soil-Water Distribution of 

Decamethylcyclopentasiloxane (D5) Using a Batch Equilibrium Method. Report to CES. Dow Corning 

Report No.: 2007-I0000-58258. 13 SEHSC (2008). Comments on Health and Environment Canada’s Draft Screening Assessments for 

Octamethylcyclotetrasiloxane (D4; CAS No. 556-67-2), Canada Gazette, Part 1, Volume 1411, No. 20, May 

17, 2008. 14 Xu, S. (2009). Temperature dependence of Air/Water, 1-Octanol/Air, 1-Octanol/Water partitioning 

coefficients of octamethylcyclotetrasiloxane (D4), and decamethylcyclopentasiloxane (D5). Centre 

Européen des Silicones (CES). CES Report. September 25, 2009. 
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ERM 4 January 2012

The distributions of emissions shown below, which were developed for 

North American regional environments, indicate that most of the D4 and 

D5 emitted to the environment partition preferentially to air for both 

compounds. 

Distribution of Mass Remaining at Steady State (%): 

Emitted to: Air Water Soil Sediment Source 

D4

Air (100%) 100.0 0.0 0.0 0.0 

Water (100%) 8.66 45.8 0.0 45.6 

Soil (100%) 88.5 0.0 11.5 0.0 

Realistic emission (Air 85%, 

Water 1%, Soil 14%) 96.0 1.14 1.69 1.13 

Kim, 2011a15

D5

Air (100%) 99.9 <0.1 <0.1 <0.1 

Water (100%) 0.744 5.21 0 94.0 

Soils (100%) 71.2 0 28.7 0 

Realistic emission (Air 95%, 

Water 0.5%, Soil 4.5%) 73.5 1.32 1.29 23.9 

Canada D5

Review16 and 

Kim, 2011b17

Distribution of D4 and D5 in the global environment is lower than for the 

regional environment. The distribution in surface media (water, soil and 

sediment) calculated by the regional model will be much higher since the 

air mass above a regional environment is limited to only a small part of 

the troposphere, which may not be the case for substances with 

atmospheric half-lives on the order of those associated with D4 and D5. 

According to the sources referenced above, both D4 and D5 are rapidly 

degraded in air via photo-oxidation and removed from soil via 

volatilization and surface catalyzed hydrolysis, but degraded slowly in 

sediments. When discharged to water, a major fraction of D4 and D5 

partitions to air and sediment due to the low water solubility, high 

Henry’s Law constant, and relatively high organic carbon-water partition 

coefficient of the substances. Any amount remaining in water is 

hydrolyzed at a rate that depends on water pH and temperature and is 

transported to downstream water bodies where the same removal 

mechanisms take place, providing more opportunity for volatilization and 

deposition to sediment to remove D4 and D5 from the water. 

Half-lives of D4 and D5 in the different environmental media are shown on 

the next page. Those half-lives were calculated based on a low OH 

 

15 Kim, J. (2011a). Fate, Distribution and Transport of Octamethylcyclotetrasiloxane (CAS No. 556-67-2) as 

Predicted by Multimedia Fugacity Modeling. Dow Corning Report No.: 2011-I0000-64103. 

16 Siloxane D5 Board of Review (2011). Op. cit. 17 Kim, J. (2011b). Fate, Distribution and Transport of Decamethylcyclopentasiloxane (CAS No. 541-02-6) in 

the Environment as Predicted by Multimedia Fugacity Modeling. Dow Corning Report No.: 2011-I0000-

64103. 
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ERM 5 January 2012

concentration (5×105 molecule/cm3), instead of the global average OH 

concentration of 7.5×105 molecule/cm3, which would result in shorter 

half-lives. Half-lives for both D4 and D5 in air and soil are less than 14 

days; in sediments, the half-lives of D4 and D5 are estimated at 1 year and 

8.5 years, respectively. Deposition from air to ground level via rainfall, 

snow, and aerosols is not expected to be significant because of the low 

water solubility, high Henry’s Law constant, and relatively low n-octanolair partition coefficient of the substances. Room-temperature n-octanol-air 

partition coefficients less than 6.5 are considered to be too “volatile” to 

deposit through dry-deposition process, even under the cold Artic 

climate.18,19

Environmental 

Compartment Half-life (days) 

 D4 Source D5 Source 

Air 14 (photo-oxidation) 10 (photo-oxidation) 

Water 16.7 at pH 7 and 12°C (hydrolysis) 

5.75 to 14.4 (volatilization) 

315 at pH 7 and 12°C 

(hydrolysis) 

Water (sediment) 1 year (degradation) 8.5 

years(degradation) 

Soils 0.05 – 5.3 (degradation) 

UK D4

Report20

0.07 (degradation) 

Canada 

D5 

Review21

Based on the properties presented in this section, ERM concluded that D4

and D5 behave similarly in the environment and that a single CSM could 

be used to represent both substances, provided the type of emissions from 

the different facilities were similar. 

 

18 Finizio, A., Mackay, D., Bidleman, T., Harner, T. (1997). Octanol-air Partition Coefficient as a Predictor of 

Partitioning of Semi-volatile Organic Chemicals to Aerosols, Atmospheric Environment, 31(15, 2289-2296. 

19 Wania, F. (2003). Assessing the Potential of Persistent Organic Chemicals for Long-Range Transport and 

Accumulation in Polar Regions, Environ. Sci. Technol., 37(7), 1344-1351. 20 Environment Agency (2009a). Op. cit. 

21 Siloxane D5 Board of Review (2011). Op. cit. 
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ERM 6 January 2012

3.0 CONCEPTUAL SITE MODEL FOR D4 AND D5 INDUSTRIES 

Based on the conclusion of the evaluation of the fate and transport 

information obtained from scientific literature and studies (Section 2.0) 

and block flow diagrams provided by the Member Companies for D4 and 

D5 (described in this section), ERM determined that a single, generic CSM 

could be used to represent human and ecological exposure to both 

substances for all facility types. A description and an evaluation of the 

block flow diagrams provided by the Member Companies (Figures 1 

through 5) are presented in Section 3.1. Section 3.2 describes the resulting 

CSM diagram, which is shown in Figure 6. 

3.1 GENERIC BLOCK FLOW DIAGRAM TEMPLATES 

The SEHSC prepared a generic block diagram template for manufacturers 

and a separate template for formulators. Three templates were provided 

to the processors, with the only differences being (1) the presence of an 

on-site wastewater treatment plant (WWTP), and (2) whether the 

discharge point is a POTW or surface water. All three options resulted in 

the eventual discharge of treated wastewater to surface water, and were 

considered to be sufficiently similar to represent the processors as a 

combined group. The templates are typical of the different facilities, but 

not all processing steps are present in all facilities. 

3.1.1 Manufacturer Block Flow Diagram Description 

The manufacturers block flow diagram shows precursor processes, 

reaction, separations, and storage tanks, and loading operation as the 

processes that lead to the production of D4 and D5 (Figure 1). The input 

material is used in the precursor processes, which result in the production 

of dichlorodimethylsilane, the precursor of the PDMSs. 

Dichlorodimethylsilane is then hydrolyzed with aqueous hydrochloric 

acid in continuous, closed reactors to produce siloxanes, resulting in cyclic 

and linear oligomeric siloxanes through silanol-silanol, silanolchlorosilane polycondensation. Further processing is also performed to 

remove residual acid and chloride and recover hydrochloric acid for reuse 

in the precursor processes. 

Linear siloxanes may then be converted into cyclic siloxanes to increase 

the amount of D4 and D5 produced and to improve their purity. The 

reaction product is a mixture of PDMSs with different molecular weights. 
FINAL 

ERM 7 January 2012

Separation processes recover the different chain-length distributions at 

different stages, and may include phase separation, flash distillation, or 

fractionation distillation. From there, the different products are stored 

separately until they are packaged for sale to off-site customers or for onsite processing. 

Due to the highly reactive nature of the organochlorosilanes when in 

contact with water or silanols, it can be assumed that they are completely 

consumed in the hydrolysis/polymerization process, given that the 

conditions of the reaction will add enough water or other reagent to 

consume all the chlorine atoms. It is therefore not necessary to consider 

exposure of humans or the environment to organochlorosilanes during 

further downstream processing and use of PDMS polymers. 

Volatile organosilanes and hydrochloric acid are emitted as gases to some 

extent during the reactions, separations, storage, and loading operations. 

Those gases are collected by local exhaust ventilation systems and 

transported to abatement systems, including incineration and scrubbers, 

from which air emissions are vented to the atmosphere. Fugitive 

emissions may be produced throughout the facility, including in valves, 

pumps, drains, and the on-site WWTP, if present. The water produced in 

the reaction vessels and in the scrubbers is typically discharged to a 

wastewater storage tank, from which it may go to either an on-site or an 

off-site POTW. In either case, the treated water is discharged to a surface 

water body. 

The sludge produced in the on-site WWTP and solid waste produced 

during the reaction and separation steps are disposed of at on-site landfills 

or shipped to off-site management systems. Depending on the type of 

solid waste, these management systems may include incinerators, energy 

recovery systems or other beneficial use, or landfills. None of the 

biological sludge or other solid wastes is disposed of as fertilizer or via 

land application. 

3.1.2 Formulator Block Flow Diagram Description 

Figure 2 shows the block flow diagram for formulators. The D4/D5

products are stored as raw materials and mechanically pumped into 

mixing equipment, where they are mixed with other materials to form 

products used by industrial facilities or consumers. Formulation may 

occur continuously or in batch processes, and typically in closed reactors. 

Product is fed into packaging systems for shipment to customers in bulk 

or in small containers. 
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ERM 8 January 2012

Both the mixing and packaging equipment typically have local exhaust 

ventilation systems that collect any gases produced during the 

formulation and transport them to pollution control equipment 

(scrubbers, condensers, energy recovery systems), with a minimal portion 

of the incoming gases being released to the air as point sources. Fugitive 

air emissions may be produced throughout the facilities, in equipment 

such as storage tanks or containers, valves, and pumps. Wastewater is 

generally only produced during mixing, and is either treated at an on-site 

facility (at D4 and/or D5 manufacturing or processing wastewater 

treatment systems) or discharged via sewer to a POTW. Solid waste is 

produced in both the mixing and packaging steps; this waste is sent off 

site for disposal, which may include thermal processes or landfilling. 

3.1.3 Processor Block Flow Diagrams Description 

There are a large number of polymers that can be prepared via 

polymerization of D4 (99% pure or in combination with D5), including 

high performance silicone oils and gums, silicone elastomer intermediates, 

and polymers used in the production of solvents, diluents, cosmetics, and 

perfumes.22 Various end blockers (i.e., materials that stop the 

polymerization reaction) can produce a wide range of functionalized 

siloxanes containing functional groups such as phenyl, amino alkyl, or 

vinyl. Polymerization is catalyzed by a strong acid or a strong base.23 

With reference to Figures 3 through 5, the D4/D5 products are stored as 

raw materials and mechanically pumped into continuous or batch reaction 

vessels for further processing. All steps in the process (storage, reaction, 

and purification) are generally carried out in closed systems with local 

exhaust ventilation that collects and transports gases produced during the 

different processing steps to a recovery system to maximize the use of D4

and D5 raw materials. The waste gases produced in the recovery 

equipment are typically routed to abatement systems, including 

scrubbers, condensers, and energy recovery systems. Fugitive air 

emissions can be produced from equipment such as valves, pumps, 

drains, or the wastewater treatment system, if present on site. 

All processing steps may also produce wastewater, which is typically 

routed to a storage area from where it is discharged into an on-site 

WWTP, an off-site POTW, or pretreated in an on-site WWTP and then 

 

22 Bluestar Silicones (1997). Technical Data Sheet n° SIL 97 127 3, March 1997. 

23 Colas, A. (2007). Introduction to Silicone Chemistry, chapter in Inorganic Polymers, Nova Science 

Publishers. 
FINAL 

ERM 9 January 2012

discharged to an off-site POTW. The solid waste produced during the 

reaction, recovery, and air emission abatement systems is shipped to an 

off-site waste management facility. 

3.1.4 Basis for a Single CSM for All Types of Facilities 

The descriptions in Sections 3.1.1 through 3.1.3 indicate that the block 

diagram for each type of facility included emissions to air, water, and 

land, as summarized below. Therefore, ERM concluded that a single CSM 

was appropriate for all types of facilities. 

Type of Type of Emission 

Facility To Air To Water To Land 

Air Emissions through Vents 

and Abatement Systems 

(Point Source Emissions) 

On-site or Off-site WWTP 

Effluent Manufacturers 

Fugitive Air Emissions Storm Water Discharge to 

Surface Waters 

Solid Waste to Fuel 

Recovery 

Air Emissions from Pollution 

Control Equipment (Point 

Source Emissions) 

Waste from Operations 

Formulators 

Fugitive Air Emissions 

Wastewater to POTW or for Offsite Treatment Activated Carbon Waste 

for Fuel Recovery 

Point Source Air Emissions Industrial Waste Water 

Discharge to POTW Processors 

with no Onsite WWTP Fugitive Air Emissions Storm Water Discharge to 

Surface Waters 

Solid Waste Disposal to 

Off-site Waste 

Management 

Point Source Air Emissions Treated Industrial Waste Water 

Discharge to Surface Waters Processors 

with On-site 

WWTP Fugitive Air Emissions Storm Water Discharge to 

Surface Waters 

Solid Waste Disposal to 

Off-site Waste 

Management 

Point Source Air Emissions Treated Industrial Waste Water 

Discharge to Off-site POTW 

Processors 

with On- and 

Off-site 

WWTP Fugitive Air Emissions Storm Water Discharge to 

Surface Waters 

Solid Waste Disposal to 

Off-site Waste 

Management 

3.2 GENERIC D4 AND D5 INDUSTRIAL CSM FOR HUMAN AND 

ECOLOGICAL RECEPTORS 

3.2.1 Procedures 

Consistent with generally accepted practice,24,25,26 ERM prepared a generic 

CSM diagram (Figure 6) summarizing the following: 

 Multimedia release pathways into the environment (such as potential 

release from storage tanks, wastewater treatment, and stacks); 

 

24 USEPA (2001). Op. cit. 

25 USEPA (1996). Op. cit. 

26 USEPA (1988). Op. cit. 
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ERM 10 January 2012

 Primary, secondary, and tertiary sources and release mechanisms for 

each of these pathways; 

 Potential exposure routes specific to each medium (air, soil, surface 

water, sediment, and groundwater); and 

 Environmental receptors specific to each medium, including both 

human and ecological receptors where relevant. 

Worker exposure pathways resulting from industrial operations are not 

considered given that in the U.S. these exposures are subject to regulation 

by the Occupational Safety and Health Administration (OSHA). As 

previously indicated, information about emissions from off-site facilities 

where the SEHSC Member Companies send some of their waste is not 

included in the mass balances discussed in Section 4.0. Furthermore, not 

all of the pathways identified in the diagram are likely to occur at each of 

the SEHSC Member Company facilities; the application of this diagram to 

any specific facility is subject to verification. 

Based on the fate and transport properties of D4 and D5, discussed in 

Section 2.0, ERM identified pathways that are complete, i.e., those 

pathways that lead to a reasonable expectation of potential exposure to 

humans or ecological receptors. The identification of complete pathways 

for D4 and D5 was based on available literature, known properties of the 

chemicals, and the information provided to ERM by the Member 

Companies via SEHSC. 

Figure 6 presents the industrial CSM. Potentially complete and 

incomplete pathways are marked in the figure as solid and dotted lines, 

respectively. The evaluation of whether each of the pathways is 

potentially complete or not is described below. 

3.2.2 Air Pathways 

With reference to Figure 6, air emissions of D4 and D5 may result from air 

treatment equipment and fugitive emission sources such as valves, 

pumps, wastewater treatment plants, beneficial sludge reuse, landfills, 

surface water, and surface soil. These air emissions are airborne vapors 

that are dispersed in the atmosphere and transported by the wind. 

During that transport, rainfall will not result in deposition of D4 and D5

because of the low water solubility, high air/water partition coefficient 

(thus no wet deposition), and relatively low n-octanol-air partition 
FINAL 

ERM 11 January 2012

coefficient (thus insignificant dry deposition)27 of the substances. 

Therefore, the deposition pathway to plants, surface soil, and surface 

water is an incomplete pathway. 

Once emitted to air or volatilized from other media, D4 and D5 remain in 

the air until they are photo-oxidized. They may be inhaled by human 

receptors either at the point of volatilization or downwind of the emission 

source. This is considered a complete pathway. 

3.2.3 Surface Soil 

During biosolids land application on surface soils, runoff may potentially 

transport D4 and D5 to surface water, but this pathway is also considered 

incomplete because of the low solubility and high organic carbon-water 

partition coefficient of the substances. From surface soils, D4 and D5 are 

unlikely to infiltrate into the ground water, but may be eroded by wind or 

volatilized and transported to air. Infiltration and migration into ground 

water and from ground water to surface water are minimized by the high 

adsorption to organic carbon and low solubility of the substances, which 

would limit their migration from soil to ground water. As a result, the 

pathways related to ground water are considered incomplete. 

The exposure of human receptors to air as a result of volatilization from 

surface soil is considered complete, given the elevated Henry’s Law 

Constants for D4 and D5. Pathways via direct exposure to surface soil via 

ingestion, uptake, or direct contact are considered to be incomplete, 

because of the rapid degradation of D4 and D5 in soil under dry conditions 

and rapid volatilization under wet conditions. 

3.2.4 Surface Water 

Sources of emissions to surface water are wastewater treatment plants, 

beneficial sludge reuse, and process equipment. Because of the low water 

solubility of the substances and rapid volatilization and adsorption to 

sediments (note that sediment pathways are retained), ingestion of, 

uptake from, or direct contact with surface water are considered 

incomplete pathways. Volatilization to air from surface water and 

subsequent exposure of human receptors is considered a complete 

pathway. 

 

27 Xu, S. (2010). Modeling Assessment of the Contribution from Surface/Air Exchange to the Deposition 

Potential for cVMS. Dow Corning Technical Report 2010-I0000-62571. 
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ERM 12 January 2012

3.2.5 Sediments 

Exposure of benthic plants, invertebrates, as well as amphibians and fish 

to sediments via uptake, direct contact, and ingestion of benthic food, 

respectively are also considered complete pathways, because D4 and D5

are relatively persistent in sediments. Exposure of human receptors to D4

and D5 in sediments via the food chain (i.e., by ingesting amphibians and 

fish) is considered an incomplete pathway because of the lack of 

biomagnification of D4 and D5 through the food chain. 

3.2.6 Landfills to Air and Ground Water 

Solid wastes generated from operations, activated carbon sent to off-site 

waste management facilities, and sludge treatment may be disposed in 

landfills, where D4 and D5 may volatilize into the air. This is a complete 

pathway. As previously indicated, infiltration of the substances into the 

ground water is unlikely because of the high soil-water partition 

coefficient and low solubility of the substances, and is considered to be an 

incomplete pathway. 

3.2.7 Summary 

The pathways retained for further consideration in fate and transport 

models and risk assessments include the following: 

 Inhalation exposure resulting from dispersion in air (this pathway 

applies only to human receptors, because ecological receptors are not 

typically evaluated for inhalation exposure risk). 

 Exposures via sediment, including direct exposure for bottomdwelling biota and indirect exposure via the food chain to ecological 

receptors. 

In summary, the generic industrial CSM summarizes a wide range of 

potential pathways for D4 and D5, but only air for human receptors and 

sediment for ecological receptors are considered to be complete pathways. 
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ERM 13 January 2012

4.0 MASS BALANCE DATA AGGREGATION 

4.1 PROCEDURES 

ERM reviewed data for 13 SEHSC Member Company sites, including two 

manufacturers, nine processors, and seven formulators. A total of six 

companies provided worksheets with input and output streams (Table 1). 

The emission streams are listed in Section 3.1.4. Because the Member 

Companies have no information about emissions at off-site facilities, those 

emissions are not included in the mass balances. 

Data aggregation decisions were driven by the need to protect 

Confidential Business Information, i.e., data were aggregated only if three 

or more Member Companies reported data for the particular stream 

evaluated. Thus, manufacturers’ data are not presented because there are 

only two manufacturers to provide information. In addition, all reporting 

processors were aggregated into a single group because there were only 

two processors in one of the categories and fewer than three reporting 

Member Companies for some of the streams in the other two categories. 

The differentiation between the presence or absence of an on-site WWTP 

at processing facilities was deemed unnecessary for the mass balance and 

the fate and transport evaluations. 

Arithmetic averages and standard deviations were calculated for each 

stream. However, because the production rate range encompasses two 

orders of magnitude for the processors and four orders of magnitude for 

the formulators, the SEHSC and ERM agreed that the data would be best 

represented by weighted averages calculated based on the input amount 

of D4 or D5 to the formulator or processor facilities. Weighted averages for 

each stream were calculated as the sum of the data for the stream for each 

facility multiplied by the ratio of the input amount D4 or D5 for that 

facility to the sum of the input amount D4 or D5 for all facilities. The 

equation is as follows: 

54 .,3,2,1

54

n etc

AStream n AllfororDDInputTotal Facilities

nFacilityforDorDInput Weighted Avg AStream



 













  

Where Stream An is each specific stream for which data were provided by 

more than three Member Companies. 
FINAL 

ERM 14 January 2012

The facilities didn’t report data for some of the streams because: (1) no 

information was available to calculate the emission rate, or (2) the stream 

was combined with the waste from other on-site activities (manufacturing, 

formulation). These facilities were excluded from the weighted average, 

i.e., the “Total Input D4 or D5 for All Facilities” in the equation above did 

not include the input for the facility not reporting data. If the facility did 

not produce the specific stream or believed the stream contained no D4 or 

D5, the stream was included in the mass balance as a zero value. Facilities 

that reported data for the same streams did so based on a mass balance or 

on existing permits. This method avoided artificially inflating the value 

for any particular stream by disregarding zero values. 

4.2 MASS BALANCE DATA AGGREGATION RESULTS 

4.2.1 Manufacturers Data Observations 

As previously indicated, no aggregation of the manufacturer’s data was 

possible because only two Member Companies reported data as 

manufacturers of D4 and D5. However, it is noteworthy that both 

manufacturers indicated that there was no contact of storm water with D4

or D5 at their facilities. 

4.2.2 Formulators Data Aggregation Observations 

No aggregation was possible for formulators of D4 because fewer than 

three Member Companies formulate with D4. Table 2 summarizes the 

arithmetic weighted averages for the output streams in terms of input D5

and the number of Member Companies that reported data for each stream. 

Observations on the information presented in Table 2 include: 

 The sum of the emission rates of D5 with respect to the input D5 was 

greater than 1. This inconsistency is explained by the way the 

calculations were performed, based on independent records of input 

and outputs. The excess amount was allocated among all six output 

streams based on their proportion to the sum of the output streams. 

 Mass-balanced emissions range from approximately 10-5 to 10-3 lb 

D5/lb D5 to storage area. The mass balance did not alter the order of 

magnitude of the emissions appreciably, because the allocated 

difference was only -1.6% of the input stream (see Tables 2 and 3). 

 Stream 2 - Waste from Operations has the greatest emissions. 

However, this stream generally receives further treatment via 

incineration, fuel blending, or other thermal treatment process that 
FINAL 

ERM 15 January 2012

will result in significant reduction or elimination of D4 or D5 before 

discharge to the environment. 

 Operations time ranges between 480 and 7,008 hr/yr, with a weighted 

average of 5,700 hr/yr. 

The mass balance calculations for the average formulating facility for D5

are presented in Table 3. To close the mass balance, the difference 

between input and output streams was allocated to each of the output 

streams based on their proportion of the total of all four output streams. 

The Member Companies agreed that this allocation appeared reasonable. 

Figure 7 presents the mass balance in the block diagram for formulators. 

As shown in the figure, the arithmetic weighted average for D5 in the 

product is 99.87%, with approximately one-half of the remaining 0.13% 

(0.059%) emitted as Stream 2 – Waste from Operations, which may be 

further treated prior to discharge. 

4.2.3 Processors Data Aggregation Observations 

Table 4 presents the arithmetic weighted averages for the output streams 

in terms of input D4 or D5 and the number of Member Companies that 

reported data for each stream. Observations on the information presented 

in Table 4 include: 

 The range of emission rates for processors is similar to those for the 

formulators. 

 The emissions of both D4 and D5 to air are greater than those to water. 

 Stream 7 – Solid Waste Disposal to Off-site Waste Management is 

greater than the emissions to either air or water or their sum. Like 

Stream 2 for the formulators of D5, this stream undergoes further 

thermal treatment that is expected to reduce the amount of D4 and D5

released to the environment significantly. 

 The range of operation time is 304 to 8,760 hr/year, with an 

arithmetic weighted average of 8,400 hr/yr. 

Table 5 shows the mass balance calculations for the output streams in 

terms of input D4 or D5 for the average processing facility that uses D4 or 

D5. The mass balance for D4 was closed by allocating any difference 

between the input and the total of the output Streams 3 through 7 to a “D4

Raw Material Reacted or Remaining in the Polymer” stream, to resolve 

differences in the calculation methods for the reported data. An allocation 

of D5 streams was completed in the same manner as for the Formulators of 
FINAL 

ERM 16 January 2012

D5, because the sum of the outputs was greater than the sum of the input. 

In this case, the “D5 Raw Material Reacted or Remaining in the Polymer” 

was equal to the value for Stream 2 – Final Polymer Produced. The 

Member Companies agreed that this allocation procedure appeared 

reasonable. 

Figures 8 and 9 present the mass balances in the block diagrams for 

processors of D4 and D5, respectively. Typically, D4 and/or D5 are utilized 

as monomers and processed into various types of polysiloxane polymers. 

As shown in Figure 8, the arithmetic weighted average for D4 reacted or 

remaining in the product is 99.66%, with approximately two-thirds of the 

remaining 0.34% (0.20%) emitted as Stream 7 – Solid Waste Disposal to 

Off-site Waste Management and almost all of the rest of the input D4

emitted to air (0.14%). 

The mass balance for D5 in Figure 9 shows that the arithmetic weighted 

average for the amount of D5 reacted or remaining in the product is 

99.29%. More than three-quarters of the remaining 0.71% (0.58%) is 

emitted as Stream 7 – Solid Waste Disposal to Off-site Waste 

Management. The next higher emission is to air (0.13%), including both 

point source and fugitive emissions, with only 0.0087% emitted to water. 

The storm water emissions are minimal for both substances (0.00038% for 

D4 and 0.000011% for D5). 
FINAL 

ERM 17 January 2012

5.0 GENERIC POTW CSM 

5.1 GENERAL TREATMENT REQUIREMENTS 

The Clean Water Act establishes that POTWs must treat wastewater to 

meet secondary treatment requirements, which are specified in Part 133 of 

Title 40 of the Code of Federal Regulations (40 CFR 133). Secondary 

treatment consists of removal of organic compounds via biological 

treatment, defined in terms of (1) both a minimum removal efficiency and 

final effluent levels of biochemical oxygen demand (BOD, a measure of 

the organic content of wastewater) and total suspended solids; and (2) a 

range of pH levels in the final effluent. 

Preliminary and primary treatment to remove solids is generally used to 

prevent interference with the aeration system in the biological treatment 

system. Advanced wastewater treatment may also be used at some 

POTWs to remove suspended solids, nutrients (i.e., nitrogen and 

phosphorus), toxic organics, or toxic metals. The need for advanced 

wastewater treatment at a specific POTW depends on the efficiency of its 

biological treatment system, the local effluent discharge requirements, 

type of industrial wastes it receives, and any reuse/recycling 

requirements for the treated effluent or the sludge produced. The sludge 

produced is usually dewatered and/or treated to reduce its disposal cost 

and to meet the requirements of certain disposal methods (such as those 

defined in 40 CFR 503 for beneficial use as a fertilizer). 

5.2 POTW POTENTIAL TREATMENT TECHNOLOGIES 

There are many technologies that can be used for wastewater treatment in 

POTWs and new technologies or improvements to existing technologies 

are continuously developed. Similarly, there are several liquid effluent 

and sludge disposal options. Table 6 presents a list that is not allinclusive. The most common treatment processes at POTWs include:28

 Primary Treatment. Grit chambers to remove dense inert particles, 

screens to remove rags and other large debris, and gravity settling 

 

28 USEPA (2009). Nutrient Control Design Manual, State of Technology Review Report, EPA/600/R-09/012. 
FINAL 

ERM 18 January 2012

tanks (primary clarifiers) to remove settleable inorganic and organic 

solids. 

 Secondary Treatment. Includes biological processes to remove colloidal 

and soluble organic matter, followed by liquid effluent disinfection. 

 Advanced Treatment. Liquid effluent filtration and nutrient removal. 

Activated sludge was the secondary treatment system most commonly 

installed in the 1970s and 1980s (in response to the 1972 Clean Water Act), 

because of their demonstrated performance and relative ease of control 

compared to other systems available at that time. In fact, the USEPA 

developed air emission factors for POTWs using an activated sludge 

system as part of the typical POTW.29 An activated sludge system 

includes an aerated, completely-mixed basin and a clarifier. A portion of 

the sludge removed in the clarifier by settlement is returned to the aerated 

basin to improve organics removal by using already acclimated 

microorganisms. 

The most common disposal methods for the liquid effluent and sludge are 

discharge to surface water bodies (rivers, lakes, oceans) and land 

application, respectively.30,31 

5.3 POTENTIAL EFFECTS OF POTW TREATMENT TECHNOLOGIES ON 

THE FATE AND TRANSPORT OF D4 OR D5

With a few exemptions, a common element in the treatment technologies 

presented in Section 5.2 is that they allow volatilization of compounds and 

produce two streams: a liquid and a solid stream. In fact, the traditional 

wastewater treatment technologies (screens, primary clarifier, activated 

sludge system, and chlorination) are usually open to the atmosphere and 

can have a very large surface area that promotes volatilization of 

compounds. Volatilized compounds are sometimes collected and treated, 

but this is done only if required by the local authority (e.g., because of 

odors), if the POTW receives hazardous air pollutants (HAPs) above 

certain levels, or if the POTW treats the HAPs in wastewater from an 

industrial facility subject to the NESHAP regulations.32 Most of the 

 

29 USEPA (1991). AP-42 Emission Factors for POTWs, Section 4.3. 

30 USEPA (2009). Op. cit. 

31 USEPA (2006). Emerging Technologies for Biosolids Management, EPA 832-R-06-005. 

32 National Emission Standards for Hazardous Air Pollutants: Publicly Owned Treatment Works, Federal 

Register, Vol. 64, No. 206, 57572-57585, October 26, 1999. 
FINAL 

ERM 19 January 2012

volatilized compounds can, therefore, be considered to be fugitive 

emissions. 

The variety of technologies used in POTWs makes it difficult to predict 

the fate of D4 and D5 in POTWs, although POTW monitoring in Canada 

demonstrated D4 and D5 removal efficiencies of >97% regardless of the 

secondary or tertiary treatment technologies used. Transfer and storage 

between processes and some of the processes used in a POTW may result 

in air emissions of D4 or D5, which may or may not be captured and 

controlled (as indicated above). Biological treatment systems, used to 

meet the secondary treatment requirements, are typically operated at a 

neutral pH, which results in a slower hydrolysis rate of D4 or D5. 

Advanced wastewater treatment may result in complete removal of D4 or 

D5 from effluent wastewater (such as air stripping), but not all POTWs 

have a treatment system that accomplishes this purpose. Some of the 

sludge processes may also remove D4 or D5. For example, thermal 

reduction would result in transformation of D4 or D5 into CO2, water, and 

silicon and lime stabilization, performed at pH values greater than 12, 

would result in faster hydrolysis.33

5.4 DESCRIPTION OF THE “TYPICAL” POTW 

As a result of the variety of technologies available for POTWs and the 

potential effects identified in Section 5.3, ERM designed a “typical” POTW 

for use in developing the CSM. The typical POTW, as designed, employs 

widely used technologies that are not expected to remove D4 or D5

completely, although they may do so. This type of POTW would be 

present in mid-size and small-size towns, which generally do not have 

regulatory requirements as stringent as those in the large POTWs found in 

densely populated areas. The assumed typical POTW uses primary and 

secondary wastewater treatment and land application for sludge disposal. 

This selection is reasonable because (1) according to USEPA, 

approximately 50% of the POTWs had only secondary treatment 

technologies and served 41% of the population in the U.S.;34 (2) land 

application is the POTW sludge disposal method that could result in the 

most exposure to the environment; and (3) the absence of advanced 

treatment makes it more likely that there would be some remaining D4

and D5 in the effluent and/or the sludge. 

 

33 Water Environment Federation (WEF) and American Society of Civil Engineers (ASCE) (2010). Design of 

Municipal Wastewater Treatment Plants, WEF Manual of Practice No. 8, ASCE Manuals and Reports on 

Engineering Practice No. 76, 5th Edition, McGraw Hill, New York, New York. 34 USEPA (2008). Clean Watershed Needs Survey 2008, Report to Congress, EPA 832-R-10-002. 
FINAL 

ERM 20 January 2012

A block diagram of the typical POTW is presented in Figure 10. It 

includes a pump station; primary treatment with coarse screening and 

primary sedimentation; secondary treatment via an activated sludge 

system (aeration basin, secondary clarification, and pumps to return 

sludge from the clarifier); and chlorination for disinfection. The liquid 

effluent is discharged to a surface water body. 

In the typical POTW, sludge is collected, stored, blended (primary sludge 

with secondary sludge), anaerobically digested (to minimize odor 

generation, destroy pathogens, and reduce the potential to attract vectors, 

in accordance with 40 CFR 503), dewatered with filter presses, and 

disposed of via land application as a fertilizer. Sludge storage is required 

during parts of the year when land application is not feasible (i.e., because 

of limitations from cold weather, some crops growing seasons, or spring 

rains). 

As indicated in Section 5.3, each of the equipment units used for treatment 

of the wastewater “mostly liquid” stream shown in Figure 10 have 

emissions to air, named “fugitive air emissions” because the typical 

POTW does not collect and treat emissions to air. Sludge is produced in 

the coarse screening, primary clarifier, and secondary clarifier along the 

“mostly liquid” stream path. That sludge is collected and stored to blend 

the primary and secondary clarifier sludges and improve the efficiency of 

the digestion system and to equalize the load entering the digester. The 

blended sludge is then pumped to an anaerobic digester operating within 

the mesophilic temperature range (32 to 38 C), pH range of 6 to 8, and 

under anaerobic conditions over a detention time period of 15 to 20 days.35 

From the anaerobic digestion tank, a “mostly-liquid” stream 

(“supernatant”), a stabilized sludge (“biosolids”), and a gaseous stream 

containing all gases produced during the digestion are generated. The 

gaseous stream goes to a waste gas burner where air is introduced to 

ensure complete combustion of the organic gases generated during the 

digestion process, thus removing any D4 and D5 in that stream. The filter 

presses, which are used for dewatering the sludge to reduce its volume, 

produce liquid and solid streams. All liquid streams produced during 

sludge treatment have relatively high organic carbon content, and are 

returned to the POTW pump station, to avoid the disruption of the 

biological processes that result from organic load variations. Equipment 

used during the transfer and processing of sludge, including pump 

 

35 WEF (1996). Operation of Wastewater Treatment Plants, Manual of Practice 11, 5th Edition, Alexandria, 

Virginia. 
FINAL 

ERM 21 January 2012

stations, blending and storage tanks, filter presses, and storage and 

transfer units, also produce fugitive air emissions. 

5.5 GENERIC CSM FOR HUMAN AND ECOLOGICAL RECEPTORS FOR 

POTWS RECEIVING WASTEWATER CONTAINING D4 OR D5 

The generic POTW CSM diagram is shown in Figure 11. Like the 

industrial CSM, exposure pathways for POTW workers were not 

included. Furthermore, the processes and resulting pathways identified 

in the diagram may not occur at each of the POTWs that receive 

wastewater containing D4 and/or D5; the application of this diagram to 

any specific POTW is subject to verification as to the processes used. 

Based on the fate and transport properties of D4 and D5, discussed in 

Section 2.0, ERM identified pathways that are complete, i.e., those 

pathways that lead to a reasonable expectation of potential exposure to 

humans or the environment. The identification of complete pathways for 

D4 and D5 was based on available literature, known properties of the 

chemicals, and the information provided to ERM by the Member 

Companies via SEHSC. The POTW CSM diagram is similar to that of 

industrial facilities producing or handling D4 or D5, with the exception 

that the primary sources are different and landfill disposal is not 

considered for the typical POTW. As a result, the pathways considered to 

be complete are the same: 

 Inhalation exposure resulting from dispersion in air (this pathway 

applies only to human receptors, because ecological receptors are not 

typically evaluated for inhalation exposure risk); and 

 Exposures via sediment, including direct exposure for bottomdwelling biota and indirect exposure via the food chain to ecological 

receptors. 
FINAL 

ERM 22 January 2012

6.0 CONCLUSIONS 

On behalf of the SEHSC, ERM evaluated the data provided by six Member 

Companies to develop (1) a generic CSM for manufacturers, formulators, 

and processors of D4 and D5; (2) mass balances for formulators of D5 and 

for processors of D4 and D5; and (3) a typical POTW block flow diagram 

and a generic CSM for POTWs. Manufacturers’ and D4 formulators’ mass 

balances could not be calculated without violating business 

confidentiality, because fewer than three Member Companies provided 

data. 

Based on the evaluation presented in this report, ERM concluded the 

following for the industrial facilities: 

 Aggregation of all facilities for the generic conceptual site model with 

arithmetic weighted averages of the emissions for the different types 

of facilities provide a useful summary of the potential fate, transport, 

and exposure pathways for these substances in the environment. 

 The greatest emissions of D4 and D5 are those to air (at the same time, 

very small emission to water), given that the solid waste or waste 

from operation streams sent off-site for disposal are thermally treated 

before being released to the environment (assuming any D4 or D5

remained after treatment). 

The typical POTW was considered to include primary treatment, activated 

sludge, chlorination, anaerobic digestion of the sludge, sludge dewatering 

via filter presses, and sludge storage and transfer. End disposal included 

discharge to surface water for the liquid stream and land application for 

the solid stream. This typical POTW was used to prepare a generic CSM 

for human and ecological receptors for POTWs that receive wastewater 

containing D4 or D5. 

After assessing the chemical and physical properties of D4 and D5 and the 

potential sources and pathways of exposure to human and ecological 

receptors, ERM concluded that the following two pathways were 

potentially complete for both the generic industrial facility and the generic 

POTW: 

 Inhalation exposure resulting from dispersion in air (this pathway 

applies only to human receptors, because ecological receptors are not 

typically evaluated for inhalation exposure risk). 
FINAL 

ERM 23 January 2012

 Exposures via sediment, including direct exposure for bottomdwelling biota and indirect exposure via the food chain to ecological 

receptors. 
TABLES 
TABLE 1

MEMBER COMPANY FACILITIES THAT REPORTED DATA

Silicones Environmental, Health and Safety Council

Facility Type Company Name Location/Name Prov

Dow Corning Carrolltown, KY

Momentive Performance Materials Waterford, NY

Bluestar Silicones USA Corp. Ventura, CA

Dow Corning HIMs, Hemlock, MDow Corning Auburn, MIDow Corning Greensboro, NCDow Corning Carrolltown, KY

Momentive Performance Materials Waterford, NY

Shin-Etsu - Facility 1 Akron, OH

Bluestar Silicones USA Corp. Ventura, CA

Dow Corning Greensboro, NC

Evonik Goldschmidt Corporation Hopewell, VA

Shin-Etsu - Facility 2 Akron, OH

Wacker Chemical Corporation Adrian, MI

Momentive Performance Materials Sistersville, W. VaMomentive Performance Materials Waterford, NY

Dow Corning Midland, MI

Dow Corning Elizabethtown, K

Processor, On- to Off-Site WWTP

Manufacturer

Formulator

Processor, No On-Site WWTP

Processor, On-Site WWTP

ERM 
TABLE 2

SUMMARY OF DATA AGGREGATION BEFORE MASS BALANCE FOR FORMULATORS

Silicones Environmental, Health and Safety Council

Stream 

No. Item

Lbs D4 / Lbs D4 to 

Storage Area

Lbs 

S

No. of Companies 2 

Arithmetic Average NA 

Standard Deviation NA 

Weighted Average NA 

No. of Companies 2 

Arithmetic Average NA 

Standard Deviation NA 

Weighted Average NA 

No. of Companies 2 

Arithmetic Average NA 

Standard Deviation NA 

Weighted Average NA 

No. of Companies 1 

Arithmetic Average NA 

Standard Deviation NA 

Weighted Average NA 

No. of Companies 2 

Arithmetic Average NA 

Standard Deviation NA 

Weighted Average NA 

No. of Companies 2 

Arithmetic Average NA 

Standard Deviation NA 

Weighted Average NA 

No. of Companies 2 

Arithmetic Average NA 

Standard Deviation NA 

Weighted Average NA 

Key:

NA = Calculation not performed to protect Business Confidentiality, as fewer than three companies reported data

Weighted Average = 

Stream Description

Calculated as the sum of: the result of multiplying each stream by the corresponding Stream 1 for each faciby the sum of the Stream 1 values for the facilities that reported values for the stream for which the weightebeing calculated

Waste Water Treatment / Storage Area

Activated Carbon Waste to Fuel Recovery

Product Mixed with D4 or D5 for Customers

Waste from Operations

1

A1A2

D4 or D5 to Storage Area

Fugitive Air Emissions from Site

Air Emissions from Pollution Control Emissions

5234

ERM 
TABLE 3

MASS BALANCE CALCULATIONS FOR FORMULATORS OF D 5

Silicones Environmental, Health and Safety Council

123456789

10111213141516171819202122

A B C D E F 

Stream 

No. Stream Description Item

Lbs D 5 / Lbs D 5 

to Storage Area

Apportioned 

Lbs D 5 / Lbs D 5 

to Storage Area

Mass-Balanced 

Lbs D 5 / Lbs D 5 to 

Storage Area 

1 D5 to Storage Area Weighted Average 1.00E+00 

A1 Point Source Air Emissions Weighted Average 3.33E-05 -5.34E-07 3.27E-05 A2 Fugitive Air Emissions Weighted Average 8.69E-06 -1.40E-07 8.55E-06 

2 Waste from Operations Weighted Average 6.03E-04 -9.67E-06 5.93E-04 3 Product Mixed with D5 for Customers Weighted Average 1.01E+00 -1.63E-02 9.99E-01 

4 Activated Carbon Waste to Fuel Recovery Weighted Average 1.87E-04 -3.00E-06 1.84E-04 

5 Waste Water Treatment / Storage Area Weighted Average 5.11E-04 -8.20E-06 5.03E-04 

--

Total Streams A1, A2, and 2 

through 5 Weighted Average 1.02E+00 -1.63E-02 1.00E+00 

--

Extra Lbs D5 / Lbs Raw Material 

Consumed Weighted Average -1.63E-02

Data or Calculations:

Columns A through D from Table 2.Column E is equal to Column D times Cell D10 divided by Cell D9 for Streams A1, A2, and 2 through 5.Column F is equal to Column D plus Column E for Streams A1, A2, and 2 through 5.Column G is equal to Column F times Cell G2 for Streams A1, A2, and 2 through 5. Cell G1 is the weighted average 

for Stream 1 and Cell G9 has the sum of the other six streams.

Column H is equal to Column F, expressed as a percentage.

Key:

= Not applicable for Rows 2 and 10

Weighted 

Average = 

Calculated as the sum of: the result of multiplying each stream by the corresponding Stream 1 for each facility and dividing by the 

Stream 1 values for the facilities that reported values for the stream for which the weighted average was being calculated

ERM 
TABLE 4

SUMMARY OF DATA AGGREGATION BEFORE MASS BALANCE FOR PROCESSORS 

Silicones Environmental, Health and Safety Council

Stream 

No. Item

Lbs D 4 / Lbs D 4 

Raw Material 

Consumed

Lbs D 5 / L

Raw Mat

Consum

No. of Companies 6 5

Arithmetic Average 1.00E+00 1.00E+

Standard Deviation 1.00E+00 1.00E+

Weighted Average 1.000E+00 1.000E+

No. of Companies 6 5

Arithmetic Average 4.83E-01 6.78E-

Standard Deviation 5.32E-01 4.99E-

Weighted Average 7.95E-01 1.0037E

No. of Companies 6 5

Arithmetic Average 3.13E-03 1.68E-

Standard Deviation 5.92E-03 2.34E-

Weighted Average 1.36E-03 1.27E-

No. of Companies 6 5

Arithmetic Average 6.67E-01 7.14E-

Standard Deviation 6.39E-05 3.94E-

Weighted Average 4.54E-05 1.50E-

No. of Companies 6 5

Arithmetic Average 4.55E-05 4.47E-

Standard Deviation 7.21E-05 1.08E-

Weighted Average 3.11E-05 8.81E-

No. of Companies 6 5

Arithmetic Average 9.78E-06 4.69E-

Standard Deviation 2.02E-05 1.24E-

Weighted Average 3.75E-06 1.16E-

No. of Companies 6 5

Arithmetic Average 7.89E-03 7.03E-

Standard Deviation 1.16E-02 9.89E-

Weighted Average 1.96E-03 5.83E-

Key:

Weighted Average = 

Stream Description

Calculated as the sum of: the result of multiplying each stream by the corresponding Stream 1 for each and dividing by the sum of the Stream 1 values for the facilities that reported values for the stream for wthe weighted average was being calculated

Solid Waste Disposal to Off-site Waste 

Management

Storm Water Discharge to Surface Waters

Industrial Waste Water Discharge to POTW

Fugitive Air Emissions

Point Source Air Emissions

7456312 Final Polymer Produced

D4/D5 Raw Material Consumed

ERM 
TABLE 5

MASS BALANCE CALCULATIONS FOR PROCESSORS OF D4 AND/OR D 5

Silicones Environmental, Health and Safety Council

123456789

101112131415161718192021222324252627

A B C D E F G H 

Stream 

No. Stream Description Item

Reported Lbs 

D 4 / Lbs D 4 

Raw 

Material 

Consumed

Reported Lbs

D 5 / Lbs D 5 

Raw 

Material 

Consumed

Apportioned 

Lbs D 5 / Lbs 

D 5 Raw 

Material 

Consumed

MassBalanced Lbs 

D 5 / Lbs D 5 

Raw Material 

Consumed Lbs D 4 / y

1 D4/D5 Raw Material Consumed Weighted Average 1.00E+00 1.00E+00 67,268,60

--

D4/D5 Raw Material Reacted or Remaining 

in the Polymer 9.97E-01 9.93E-01 9.93E-01 67,039,99

2 Final Polymer Produced Weighted Average 7.95E-01 1.0037E+00 -1.08E-02 9.93E-01 53,467,163 Point Source Air Emissions Weighted Average 1.36E-03 1.27E-03 -1.37E-05 1.26E-03 91,626 4 Fugitive Air Emissions Weighted Average 4.54E-05 1.50E-05 -1.61E-07 1.48E-05 3,051 

5 Industrial Waste Water Discharge to POTW or Surface Water Weighted Average 3.11E-05 8.81E-05 -9.46E-07 8.71E-05 2,094 

6 Storm Water Discharge to Surface Waters Weighted Average 3.75E-06 1.16E-07 -1.25E-09 1.15E-07 253 7 Solid Waste Disposal to Off-site Waste Management Weighted Average 1.96E-03 5.83E-03 -6.26E-05 5.76E-03 131,585 

-- Total Streams 3 through 7 3.40E-03 7.20E-03 -7.74E-05 7.12E-03-- Total (Reacted plus Streams 2 through 7) 67,268,35

-- Total Streams 2 through 7 1.011E+00 -1.09E-02 1.00E+00-- Extra Lbs D5 / Lbs Raw Material Consumed -1.09E-02

Data and Calculations:

1. Columns A through E from Table 4. All values for Streams 1 through 7 are weighted averages with respect to the Stream 1 amounts.2. The mass balances for D4 and D5 were accomplished as follows: 

D4: Assign the amount missing from columns F and G (Row 2 minus Row 10) to a "D4/D5 Raw Material Reacted or Remaining in the Polymer" stream 

D5: Apportion the "Extra Lbs D5/Lbs D5 Raw Material Consumed" by:

- Adding the Reported lbs D5 / Lbs D5 Raw Material Consumed for Streams 2 through 7.

- Calculating the apportioned amount for each stream (Column H) by multiplying the values in Column G for each stream by the ratio of Cell G- Calculating the mass-balanced values in Column I by adding Columns G and H for each stream.- Assigning the Lbs D5/yr calculated for Stream 2 to the "D4/D5 Raw Material Reacted or Remaining in the Polymer" stream (Row 3) for D5.

Key:

= Not applicable

Weighted 

Average = 

Calculated as the sum of: the result of multiplying each stream by the corresponding Stream 1 for each facility and dividing by the sum of the Stream 1 values for the facilities that reported values for the stream for which the weighted average was being calculated

ERM 
FINAL 

TABLE 6 

POTENTIAL TECHNOLOGIES AND DISPOSAL OPTIONS FOR PUBLICLY OWNED TREATMENT WORKS 1

Silicones Environmental, Health and Safety Council 

ERM 31 January 2012 

Treatment 

Type General Objective Technologies/Disposal Options 

Removal of solids 

 Coarse screens for removal of coarse solids 

 Grinding of solids after coarse-solid removal 

 Sedimentation using primary clarifiers to remove settleable solids 

Primary 

Treatment Removal of oil and 

grease, petroleum 

products, and toxic 

compounds 

 Flow equalization 

 Skimming 

 Flocculation 

 Pre-aeration 

 Flotation 

 Chemical precipitation 

Secondary 

Treatment 

Removal of organic 

compounds via 

biological treatment 

 Activated sludge (consisting of an aerated, completely-mixed basin and a clarifier; a portion of the 

sludge removed in the clarifier by settling is returned to the aerated basin to improve organics 

removal by using already acclimated microorganisms) 

 Aerated lagoons (no return sludge) 

 Stabilization ponds (partially aerobic and partially anaerobic) 

 Trickling filters (tanks filled with media where the microorganisms attach) 

 Sequential batch reactors (similar to activated sludge, but operated on a batch basis) 

 Constructed wetlands 

Advanced 

Treatment 

Removal of 

pathogens/viruses, 

solids, nonbiodegradable organics, 

nutrients (nitrogen and 

phosphorus), volatile 

compounds (organics or 

ammonia), dissolved 

solids 

 Chlorination 

 Granular-medium filtration 

 Chlorination 

 Nitrification/denitrification (removal of nitrogen) 

 Addition of powdered activated carbon to aeration basins 

 Chemical precipitation in activated sludge or separate vessels 

 Carbon adsorption using granular activated carbon vessels 

 Harvesting of algae in stabilization ponds 

 Air stripping 

 Chemical oxidation 

 Reverse osmosis 

 Ion exchange 

 Membrane filtration 

Sludge 

Treatment 

Stabilization, removal of 

pathogens or viruses, 

volume reduction 

 Storage 

 Gravity or flotation thickening 

 Digestion, aerobic or anaerobic, with or without energy recovery 

 Chlorine oxidation 

 Lime stabilization 

 Heat treatment 

 Chemical conditioning 

 Disinfection 

 Dewatering using vacuum filters, filter presses, horizontal belt filters, centrifuges, drying beds, or 

lagoons 

 Thermal drying 

 Composting 

Liquid 

Effluent 

Disposal 

Final Disposal 

 Discharge to surface waters or wetlands 

 Injection into aquifers to replenish ground water 

 Land treatment 

 Reuse (agricultural and landscape irrigation, industrial processes, or toilet flushing) 

Sludge 

Disposal Final Disposal 

 Beneficial use as fertilizer for properly treated sludge (“biosolids”) 

 Landfill disposal 

 Incineration, fuel blending, or thermal reduction followed by landfill disposal 

 Reclamation of strip mines 

 Lagoon disposal 

Sources: 

A. Water Environment Federation (WEF) and American Society of Civil Engineers (ASCE) (2011). Design of Municipal Wastewater Treatment Plants, WEF Manual of Practice 

No. 8, ASCE Manuals and Reports on Engineering Practice No. 76, 5th Edition, McGraw Hill, New York, New York. 

B. Water Environment Federation (1996). Operation of Wastewater Treatment Plants, Manual of Practice 11, 5th Edition, Alexandria, Virginia. 

____________ 

1 Not intended to be an all-inclusive list. 
FIGURES 
FIGURE 1

BLOCK FLOW DIAGRAM TEMPLATE FOR MANUFACTURERS OF D4 OR D5

Silicones Environmental, Health and Safety Council

Precursor Processes

Vent / Abatement Fugitive Air 

Emissions

Reaction Separations Storage Tanks Loading Operations

On-site Landfill

On-site WWTP

Off-site WWTP Off-site Landfill

Stormwater Run-off

Wastewater 

Storage

Note:1. Further processing of products will be 

detailed on a separate document
Block Flow Diagram ‐ Formulator of D4 / D5

Site Boundary

1 Storage area Mixing equipment Packaging equipmen

Pollution control

equipment

A1

Fugitive air

releases

Waste water

treatment

/Storage area

A2

5

FIGURE 2

BLOCK FLOW DIAGRAM TEMPLATE FOR FORMULATORS OF D4 OR D5

Silicones Environmental, Health and Safety
Storage

D4 / D5

Storage

Intermediates

Storage

Final Polym

Storage

Recovered D4 D5

Storage

Wastewater

Reactor

Polymerization

Reactor

Polymerization

Recovery

D4 / D5

Purification

Final Polymer

Abatement

D4 / D5

Storm water Solid Waste

Fugitive

5 6 7

4 3

1 

Block Flow Diagram: Processor of D4/D5 with on-site WW

Treatment

Wastewater

To Surface Waters

To Off-site Waste Manageme

FIGURE 3

BLOCK FLOW DIAGRAM TEMPLATE FOR PROCESSORS OF D4 OR D5 

WITH ON-SITE WASTEWATER TREATMENT PLANT

Silicones Environmental, Health and Safety Council
Storage

D4 / D5

Storage

Intermediates

Sto

Final P

Storage

Recovered D4 D5

Storage

Wastewater

Reactor

Polymerization

Reactor

Polymerization

Rec

D4 

Purification

Final Polymer

Abatement

D4 / D5

Storm water Solid Waste

Fugitive

5 6 7

4 3

1 

Block Flow Diagram: Processor of D4/D5 with no on-s

To Off-site POTW

To OffWaste Manag

FIGURE 4

BLOCK FLOW DIAGRAM TEMPLATE FOR PROCESSORS OF D4 OR D5 

WITHOUT ON-SITE WASTEWATER TREATMENT PLANT

Silicones Environmental, Health and Safety Council
Storage

D4 / D5

Storage

Intermediates

S

Fina

Storage

Recovered D4 D5

Storage

Wastewater

Reactor

Polymerization

Reactor

Polymerization

R

D

Purification

Final Polymer

Abatement

D4 / D5

Storm water Solid Waste

Fugitive

5 6 7

4 3

1 

Block Flow Diagram: Processor of D4/D5 with on & o

Treatment

Wastewater

To Off-site POTW

To OfWastMana

FIGURE 5

BLOCK FLOW DIAGRAM TEMPLATE FOR PROCESSORS OF D4 OR D5 

WITH ON-SITE AND OFF-SITE WASTEWATER TREATMENT PLANTS

Silicones Environmental, Health and Safety Council
Process 

Equipment

Air 

Emissions

Airborne 

Vapors

Beneficial 

Sludge 

Reuse

Surface 

Soil

Volatilization

Erosion

Runoff

Surface 

Water

Volatilization

Surface 

Water

Deposition Sediments

Direct Contact

Surface 

Soil

Air Inhalation of VapoAir Inhalation of Particu

Direct Contact

Ingestion of Aquatic 

Food

Ingestion of Water

Uptake from Water 

Uptake from Soil

Ingestion of Soil

Ingestion of Terrestria

Food Items

Ingestion of Fruits

Vegetables, Meat, M

Direct Contact

Air Inhalation of Vapors

Storm Water 

Runoff

Solid Waste 

from 

Operations, 

Activated 

Carbon Disposal

Ground 

Water Landfill

Infiltration

Dispersion

Ingestion of Drinking 

Inhalation of Vapors 

Showering

PRIMARY 

SOURCES

PRIMARY 

RELEASE 

MECHANISMS

SECONDARY 

SOURCES

SECONDARY 

RELEASE 

MECHANISMS

TERTIARY SOURCES

TERTIARY 

RELEASE 

MECHANISMS

MIGRATION 

PATHWAYS

EXPOSURE 

ROUTES

FIGURE 6

GENERIC D4 AND D5 INDUSTRIAL CONCEPTUAL SITE MODEL FOR HU

ECOLOGICAL RECEPTORS

Silicones Environmental, Health and Safety Council

Uptake from Sedime

Ingestion of Benthic F

Incomplete pathway; substance degrades rapidly in air, water, and surface soil and adsorbs strongly to soilPotentially complete pathway

Key:

Air 

Treatment 

Equipment, 

Storage and 

Process 

Vessels

Waste 

Water 

Treatment 

Plant

Sludge 

Treatment

Landfill

31 January 2012

Infiltration

Deposition

To 1

1
Site Boundary

Mixing equipment 

Note:(1) Values shown are weighted averages 

based on data from four companies.

FIGURE 7

31 January 2012

MASS BALANCE FOR FORMULATORS OF D5

Silicones Environmental, Health and Safety Council

1 Storage area Mixing equipment Packaging equipment

Pollution control 

equipment

34

A1

2

Fugitive air 

releases

Waste water 

treatment 

/Storage area

A2

5

Fugitive Air Emissions:

64.2 lb/yr (0.00086%)

Point Source Air Emissio

246 lb/yr (0.0033%)

Ac

Pro

7,49

Was

4,

Waste Water to POTW or for Off-site Treatment:

3,776 lb/yr (0.050%)

D5 to Storage Area:

7,507,346 lb/yr
31 January 2012

FIGURE 8

MASS BALANCE FOR PROCESSORS OF D4

Silicones Environmental, Health and Safety Council

Storage

D4 / D5

Storage

Intermediates

Storage

Final Polymer

Storage

Recovered D4

Storage

Wastewater

Reactor

Polymerization

Reactor

Polymerization

Recovery

D4

Purification

Final Polymer

Abatement

D4 

Storm water Solid Waste

Fugitive

5 6 7

4 3

1 

D4 Raw Material 

Consumed: 

67,268,603 lb/yr

Point Source Air Emissions: 

91,626 lb/yr (0.14%)

Fugitive Air Emissions:

3,051 lb/yr (0.0045%)

Industrial Waste Water 

Discharge to POTW or 

Surface Water:

2,094 lb/yr (0.0031%)

Solid Waste Di

to Off-site W

Manageme

131,585 lb/yr (0

Note:(1) Output values shown are weighted averages based on

D4 Raw Material Consumed data from six companies.

Storm Water Discharge to 

Surface Waters:

253 lb/yr (0.00038%)
31 January 2012

FIGURE 9

MASS BALANCE FOR PROCESSORS OF D5

Silicones Environmental, Health and Safety Council

Storage

D5

Storage

Intermediates

Storage

Final Polymer

Storage

Recovered D5

Storage

Wastewater

Reactor

Polymerization

Reactor

Polymerization

Recovery

D5

Purification

Final Polymer

Abatement

D5 

Storm water Solid Waste

Fugitive

5 6 7

4 3

1 

D5 Raw Material 

Consumed: 

4,354,908 lb/yr

Point Source Air Emissions: 

5,477 lb/yr (0.13%)

Fugitive Air Emissions:

65 lb/yr (0.0015%)

Industrial Waste Water 

Discharge to POTW or 

Surface Water:

379 lb/yr (0.0087%) Storm Water Discharge to 

Surface Waters:

0.5 lb/yr (0.000011%)

Solid Waste Di

to Off-site W

Manageme

25,104 lb/yr (0

Note:(1) Output values shown are weighted averages based on 

D5 Raw Material Consumed data from five companies.
Sewer Pump Station Coarse Screening Primary Clarifier Secondary Clarifier Aeration Basin

Sludge 

Collection, 

Blending, 

and Storage

Sludge

Pump 

Station

Pump 

Station

Anaerobic 

Digestion

Filter 

Presses

Storage and 

Transfer

Fugitive Air 

Emissions

Fugitive Air 

Emissions

Key:

Mostly Liquid StreamMostly Sludge Stream

Air Stream

FIGURE 10

GENERIC BLOCK FLOW DIAGRAM FOR POTWs R

WASTEWATER CONTAINING D4 OR D5

Silicones Environmental, Health and Safety Co

POTW Publicly Owned Treatment Works

1

Note: See Figure 11 for further information on Streams 1, 2, and 3.

Chlorination

31 January 2012

Waste Gas Burner
2

Fugitive Air 

Emissions

Airborne 

Vapors

Biosolids Land 

Application

Surface 

Soil

Volatilization

Erosion

Runoff

Surface 

Water

Volatilization

Deposition Sediments Direct Contact

Air Inhalation of VaporsAir Inhalation of Particulates

Direct Contact

Ingestion of Aquatic Foo

Ingestion of Water

Uptake from Water 

Uptake from Soil

Ingestion of Soil

Ingestion of Terrestrial 

Food Items

Ingestion of Fruits, 

Vegetables, Meat, Milk

Direct Contact

Air Inhalation of Vapors

Discharge 

to Surface 

Water

Infiltration

Dispersion

Ground 

Water

Ingestion of Drinking Wat

Inhalation of Vapors 

while Showering

PRIMARY 

SOURCES

PRIMARY 

RELEASE 

MECHANISMS

SECONDARY 

SOURCES

SECONDARY 

RELEASE 

MECHANISMS

MIGRATION 

PATHWAYS

EXPOSURE 

ROUTES

FIGURE 11

GENERIC CONCEPTUAL SITE MODEL FOR HUMAN AND ECO

RECEPTORS FOR POTWs RECEIVING WASTEWATER CONTAIN

Silicones Environmental, Health and Safety Council

Uptake from Sediments 

Ingestion of Benthic Foo

Incomplete pathway; substance degrades rapidly in air, water, and surface soil and adsorbs strongly to soilPotentially complete pathway

Key:

13

31 January 2012

Ingestion of Amphibians

Deposition

Note: Primary Sources are shown on Figure 10.
Attachment 3

Table of SEHSC Member Company D4/D5 Manufacturing, 

Processing, and Formulating Facilities in the U.S.
Silicones Environmental, Health and Safety Council

January 31, 2012

ATTACHMENT 3

SEHSC Member Company D4/D5 Manufacturing/Processing/Formulating Facilities in the U.S.*

Company Facility Name Address Facility Description Discharge 

(Direct/Indirect)

Bluestar Silicones

USA 

Corporation

Ventura Plant 320 W Stanley Avenue

Ventura, CA 93001

D4 processor

D5 processor and 

formulator

Indirect

Dow Corning 

Corporation

Carrollton Plant 4770 Highway 42 East 

Carrollton, KY 41008

D4 manufacturer and 

formulator

D5 manufacturer and 

formulator

Direct

Greensboro Plant 2914 Patterson Street

Greensboro, NC 27407

D4 processor and 

formulator

D5 formulator

Indirect

Auburn Plant 5300 11 Mile Road 

Auburn, MI 48611

D4 formulator

D5 formulator

Indirect

Healthcare Industries 

Materials Site 

1635 N Gleaner Road

Hemlock, MI 48626

D4 formulator

D5 formulator

Indirect

Midland Plant 3901 S Saginaw Road

Midland, MI 48640 

D4 processor

D5 processor

Indirect

Elizabethtown Plant 760 Hodgenville Road 

Elizabethtown, KY 42701 

D4 processor

D5 processor

Indirect

Evonik 

Goldschmidt 

Corporation

Hopewell Plant 914 East Randolph Road 

Hopewell, VA 23860

D4 processor

D5 processor

Indirect

Momentive

Waterford Plant 260 Hudson River Road

Waterford, NY 12188

D4 manufacturer, 

processor, and formulator

D5 manufacturer, 

processor, and formulator

Direct

Sistersville Plant 3500 S State Route 2

Friendly, WV 26146

D4 processor

D5 processor

Direct

Shin-Etsu Silicones 

of America, Inc.

Shin-Etsu Silicones of 

America, Inc.

1150 Damar Drive 

Akron, OH 55305

D5 formulator None

Shincor Silicones, Inc. 1030 Evans Avenue Akron, 

OH 55305

D4 processor None

Wacker Chemical 

Corporation

Wacker Chemical 

Corporation

3301 Sutton Road 

Adrian, MI 49221

D4 processor

D5 processor

Direct

*This list focuses exclusively on facilities that manufacture, process, or formulate D4 or D5 with associated potential 

wastewater discharges. For purposes of this list, process means facilities that react D4 or D5 to create other substances. 

Formulate means those facilities that mix/blend D4 or D5 to create products. Facilities that only import or store D4 or D5 

are not included. No facility information is included for SiVance, LLC.