Organosilicon Materials

Frontmatter

1. Industrial Organosilicon Materials, Their Environmental Entry and Predicted Fate

Abstract

Commercial organosilicon materials have many physical forms and applications, so it makes sense to focus environmental fate and effects attention on those which may have environmental exposure. This chapter summarizes the structures, manufacturing processes, applications, and production volumes of the important industrial organosilicon materials. Environmental entry and initial fate are discussed by classifying the materials according to physico-chemical properties, then estimating the volume of each class which enters the various environmental compartments. Estimated and observed physico-chemical properties for each material class were used to predict the ultimate environmental fate. By condensing a vast array of materials having the potential for environmental exposure into three distinct categories, these classes have become the focal point of environmental studies and the subsequent chapters of this volume.

R. B. Alleni, P. Kochs, G. Chandra

2. Methods for the Extraction and Detection of Trace Organosilicon Materials in Environmental Samples

Abstract

Silicone manufacturers worldwide have organized to study the environmental impact of organo-silicon materials, focusing primarily on polydimethylsiloxanes (PDMS), which constitute the largest source of organosilicon materials in wastewater treatment streams. This chapter reviews literature methods for the extraction and detection of PDMS and presents recently developed, improved analytical methods. These more effective techniques are currently being used in North America, Europe, and Japan to determine concentrations of silicones in environmental samples.

J. C. Carpenter, R. Gerhards

3. Eco-Relevant Properties of Selected Organosilicon Materials

Abstract

This chapter summarizes the estimation/measurement techniques and data available for several physico-chemical properties of selected organosilicon materials. A deliberate emphasis is placed on equilibrium partition coefficients, because of their widespread use in performing environmental calculations. Physico-chemical properties are listed in tabular form, along with conventional properties (density, vapor pressure, etc.), equilibrium partition coefficients (such as log Kow), and eco-relevant properties (like Henry’s law constant). The focus will center on:

• linear siloxanes with structure Me₃SiO[SiMe₂O]_n SiMe₃ where n = 0 to 6
• cyclic siloxanes with structure [Me₂SiO]_x where x = 3 to 8
• a number of silanols, classified separately from siloxanes

Limitations of the estimation and experimental methods are also discussed. Where applicable, comparison has been provided between the selected organosilicon compounds and other organic compounds.

S. M. Mazzoni, S. Roy, S. Grigoras

4. Ecotoxicity Testing Challenges of Organosilicon Materials

Abstract

Some of the physico-chemical properties which make organosilicon materials so useful commercially also make their ecotoxicity testing difficult using conventional methods. Standard protocols may not be appropriate for testing organosilicon materials, as many of the techniques were developed for water soluble, stable, and chemically distinct substances. For this reason, it is strongly recommended that the first step in ecotoxicity testing be a determination of the physico-chemical properties of the specific materials under scrutiny. In the absence of established protocols, it is advisable to use this information as the basis for discussion with regulatory authorities. This discussion would help in conducting the tests in a manner that yields meaningful scientific results, yet satisfies regulatory requirements.

C. Stevens, R. B. Annelin

5. Organoalkoxysilanes, Organosilanols, and Organosiloxanols

Abstract

A variety of organoalkoxysilanes are utilized commercially, and this chapter describes their synthesis, applications, ecotoxicity, and hydrolytic instability. The hydrolysis products of organoalkoxysilanes are organosilanols and organosiloxanols. The chemical and physical properties, synthesis, environmental formation, and fate of these materials are also summarized.

J. L. Spivack, E. R. Pohl, P. Kochs

6. Volatile Methylsiloxanes

Abstract

Volatile methylsiloxane (VMS) compounds are low molecular weight materials with significant vapor pressure under ambient environmental conditions. Although these products are primarily used in manufacturing higher molecular weight polydimethylsiloxanes, the cyclic VMS materials are also used in cosmetics and other personal care products as carriers and emollients. VMS volatilizes into the atmosphere from these consumer applications, and some also enters the surface waters through sewage treatment plants (STPs). This chapter focuses on the environmental fate and effects of VMS in the atmospheric and aquatic ecosystems. Environmental fate models of VMS in air and sewage treatment plants are described and compared with environmental monitoring data. Laboratory programs are discussed to evaluate toxicity and fate in aquatic ecosystems, and an assessment of aquatic risk is presented.

J. F. Hobson, R. Atkinson, W. P. L. Carter

7. Polydimethylsiloxane

Abstract

Siloxanes are a diverse group of materials which may take the form of fluids, elastomers, or resins. This chapter’s focus is on polydimethylsiloxane (PDMS) fluids. Many applications result in the disposal of PDMS fluids with down-the-drain products, which are eventually transported to wastewater treatment plants (WWTPs). The authors summarize the properties and prevalence of these materials, as well as their potential to enter the environment, primarily as a component of wastewater treatment plant sludge. This work examines the ecological fate, effects, and risk of PDMS in water, soil, and sediment.

N. J. Fendinger, R. G. Lehmann, E. M. Mihaich

8. Polyethermethylsiloxanes

Abstract

Polyethermethylsiloxanes (PEMS) are copolymers consisting of a siloxane backbone with one or more methyl groups on the silicon atom substituted with a polyoxyalkylene (i. e. polyether) group. Commercial PEMS materials are used for a wide variety of applications, including the manufacture of polyurethane foams, textiles, personal care products, paints, and surface coatings. This chapter summarizes the structure, manufacturing processes, and applications of this important class of organosilicon compounds. In addition, the physical and chemical properties of PEMS are addressed in relation to the transport, fate, and effects of these materials in the environment.

D. E. Powell, J. C. Carpenter

9. Regulatory Status of Silicones in the United States

Abstract

This chapter provides an overview of the principal chemical regulatory statutes in the United States. Federal laws are discussed, followed by material-specific laws and an analysis of their impact on silicones. Each section includes an overview of the statutory provisions, and covers key trends and indicators. The chapter concludes with a summary of global trends toward risk assessment and environmental accountability.

J. A. Hatcher, G. S. Slater

10. Regulatory Status of Silicones in Europe

Abstract

The class of materials known generically as “silicones” is a chemically diverse group, with a wide range of uses in consumer and industrial applications. As in any new product development, designing and manufacturing silicones for commercial use requires that compliance with national and European Union (EU) regulations be an essential element, regardless of the intended market. EU legislation in the past has focused primarily on health issues, but increasing attention is now being paid to the environmental aspects of chemical production, use, and disposal. Introduction of an eco-labeling system for many products is an indication of the increased consumer awareness of environmental issues and effects. A “cradle-to-grave” approach has been adopted in this chapter to address regulatory control over the entire product life cycle, from manufacture through ultimate disposal.

D. Wischer, C. Stevens

11. Regulatory Status of Silicones in Japan

Abstract

In the 1950s, Japan experienced a period of rapid technical growth and modernization, and by 1970, it had the free world’s second-largest gross national product. During this period of urbanization and industrial development, a series of incidents provided the initial motivation to create a legislative framework for preventing pollution. This chapter outlines the various statutes, and describes the role of the Japanese Environment Agency to coordinate government and civilian efforts to prevent the release of hazardous substances to the air, water, or soil compartments of the environment. Also included is the scheme for chemical screening and safety evaluation for new and existing materials, with a discussion of environmental monitoring and risk assessment. Environmentally, silicones are of minimal concern in Japan.

Y. Miyakawa

12. The Silicone Industry and its Environmental Impact

Abstract

This chapter presents an overview of silicone technology and the global silicone industry, including the unique properties of silicones, diverse applications, major producers, and their market share. Industry stewardship initiatives and environmental stewardship activities are also discussed. In addition, the missions and membership of the three regional (U.S., Europe, and Japan) health, environmental, and safety organizations are summarized. Although these groups deal with the health, environmental, regulatory, and operational safety aspects of organosilicon materials, the focus in this chapter (and the volume as a whole) has been exclusively on the environmental sciences. The chapter concludes with an environmental impact assessment of three environmentally mobile materials: volatile methylsiloxanes, polydimethylsiloxanes, and polyethermethylsiloxanes.

G. Chandra, L. D. Maxim, T. Sawano

Backmatter