Introduction

In the United States, approximately 25% of all plastics produced are used in packaging. While paper and paperboard is the most commonly used packaging material, plastics are the most rapidly growing. They have extensive use in containers, in flexible packaging, as blisters, trays, and other forms. While they are very often used alone, they also have important applications where they are combined with other materials in coatings or as layers in multilayer structures. In such applications, plastics contribute important properties such as ease of forming, heat sealability, barrier, flexibility, impact strength, light weight, reduced package size, and low cost. However, from time to time, plastics packaging has suffered from negative consumer perceptions ranging from the belief that all plastics are associated with dangerous emissions when they are burned to the fear that components migrating from plastics packaging into products may damage human health. While in many cases there is some factual basis for such concerns for a few plastics, in most cases the fear is both out of proportion to the danger and extended to other plastics materials where there is no reason for concern. The environmental benefits associated with plastics packaging, on the other hand, are rarely appreciated.

Since most packages have a lifetime of less than one year, the series of Environmental Protection Agency (EPA) reports on the U.S. municipal solid waste (MSW) stream, while not precisely targeted at reporting uses of plastics and other packaging materials, provides a useful estimate of overall use of plastics and other materials in packaging, as well as information about the contribution of various types of plastics packaging to waste problems. Figure 4.1 shows

Plastics and the Environment, Edited by Anthony L. Andrady. ISBN 0-471-09520-6 © 2003 John Wiley & Sons, Inc.

Wood

Other

Aluminum 2.7%

Glass 15.2%

Steel 4.1%

Plastics 13.7%

Wood

Other

Aluminum 2.7%

Glass 15.2%

Steel 4.1%

Plastics 13.7%

Figure 4.1. Packaging in U.S. municipal solid waste stream, 1998 [1].

Paper & paperboard 54.0%

Figure 4.1. Packaging in U.S. municipal solid waste stream, 1998 [1].

the proportions of various types of packaging materials in U.S. MSW generated (prior to recovery) in 1998. As can be seen, plastics accounted for slightly less than 14% of all packaging in MSW by weight [1].

However, the contribution of plastics to landfill is underrepresented by this value. The important measure in a landfill is contribution by volume, not weight. Because of their low density compared to materials such as metals and glass, plastics occupy a greater proportion of landfill space by volume than they do by weight. For a variety of reasons, it is exceedingly difficult to obtain accurate estimates of the contribution to landfill volume of various materials, including plastics packaging. The EPA has published such estimates on occasion, but they must be regarded as only rough approximations. Figures 4.2 and 4.3 show the relative proportions of plastics in discarded packaging (after recycling) in U.S. MSW in 1996 by weight and by volume, respectively. As can

Wood

Other

Alumir 2.3%

Glass 19.0%

Wood

Other

Alumir 2.3%

Glass 19.0%

Figure 4.2. Packaging discarded in United States, by weight, 1996 [2].

Paper & paperboard 43.1 %

Figure 4.2. Packaging discarded in United States, by weight, 1996 [2].

Wood Other

Wood Other

Figure 4.3. Packaging discarded in United States, by volume, 1996 [2].

Figure 4.3. Packaging discarded in United States, by volume, 1996 [2].

-♦- Plastics packaging

Plastics proportion of packaging

Figure 4.4. Plastics in packaging in U.S. municipal solid waste stream [1].

-♦- Plastics packaging

Plastics proportion of packaging

Figure 4.4. Plastics in packaging in U.S. municipal solid waste stream [1].

be seen, plastics represent a much larger proportion by volume (37%) than by weight (18%) [2]. It should be noted that Figures 4.1 and 4.2 are not directly comparable, since Figure 4.1 shows proportions before recovery for recycling, and Figure 4.2 shows proportions after recovery. In 1996, plastics amounted to 11.8% of the packaging in municipal solid waste, before recovery. Figure 4.4 shows the growth in both absolute amounts and proportions of plastics in the packaging component of U.S. municipal solid waste.

In this chapter, we will examine the types of plastics packaging, their fabrication methods, their occurrence in municipal solid waste, environmental impacts (both positive and negative) associated with their use and disposal, and packaging changes that can reduce those environmental impacts. First, we will examine the basic functions of packaging and the role plastic packaging plays in meeting those functions.

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