Environmental Engineering Reference
In-Depth Information
120
99
100
80
62.9
62
60
51.6
47.1
34.9
40
31
30.9
25.3
20
0
Figure 12.5
Recycling rates in the United States by material in 2006.
From Environmental Protection Agency (EPA), 2007.
Aluminum and steel can be recycled and used to produce the same type of container with-
out significant differences in comparison to using virgin materials. Unfortunately, paper and
plastics do not have the same advantage. Virgin and recycled paper fiber differs significantly
from each other mainly due to irreversible changes made to the fibers during drying/repulping
and the presence of contaminants in recycled fibers (Hubbe et al., 2007). These factors limit
the recyclability of fibers to few cycles and create the need of constant addition of virgin mate-
rials. In addition, direct contact with food products, waxes, and oils prevents paper from being
recycled.
Plastics also change during recycling and processing. Even when it is technically possible
to include recycled resins into new packages, their properties are different to those made with
virgin resins, so typically plastics from recycled containers are used as raw materials for lesser
quality products, known as downcycling (Weeks, 2007) (Table 12.5).
Food safety and recycling
The use of recycled glass, steel, and aluminum to make new containers for food contact do not
present concerns about the potential carryover of contaminants because these materials are
resistant to contamination and are subjected to extremely high temperatures during reprocess-
ing (Food and Drug Administration [FDA], 2006). In the United States, recycled cellulose
fibers can be used for food-contact packaging when the recycled paper is made from sources
that do not contain “any poisonous or deleterious substance which is retained in the recovered
pulp and that migrates to the food” (Title 21 Code of Federal Regulations, Section 176.260,
Pulp from reclaimed fiber).
Recycled plastics, on the other hand, present some concerns about:
The potential carryover of contaminants into new containers.
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The accidental incorporation of nonregulated plastics for food contact use into food-
contact packaging.
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The adjuvants used during recycling are not appropriate for food contact (FDA, 2009).
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