Plastics, Food Containers, and Recycling
Name: Diane D.
Hello. I am an art teacher and we do
experiment with combining mediums. Since we often
use plastic containers as well as tins, my students
and I are interested in learning more about
plastics and recycling them. Could you tell me which
plastics are used to be recycled into the foam food
containers that restaurants use? What does the
"new" foam consist of? What toxic chemicals are
released from the convergence or melting of the
original plastics and how are they contained during
As a general statement, one type of plastic cannot be recycled into a
chemically different type. Foam food containers are typically expanded
polystyrene ("Type 6" recycling designation). There are 7 different
common plastics designated for recycling. These are: Type 1
Polyethylene Terepthalate (e.g. soft drink bottles), Type 2 High
Density Polyethylene (e.g. milk jugs), Type 3 PVC (e.g. some cling
films, and blister packaging), Type 4 (Low Density Polyethylene (e.g.
plastic bags and Tupperware), Type 5 Polypropylene (e.g. margarine
tubs), Type 6 Polystyrene (insulation foam sheets, plastic models,
cheap toys), and Type 7 (everything else!, but commonly polycarbonate
The entire purpose of having these distinct types of recyclables, is
to prevent one type of plastic from getting mixed up with other types.
One type can also not be converted into another type. The idea is that
(for example) recycled plastic identified as Type 1 (Polyethylene
Terepthalate) can be ground into small pellets and either mixed up to
20% with "virgin" plastic of the same type to make new plastic
articles of the same material. Similarly, old milk jugs (Type 2 H.D.
Polyethylene) can be ground up and used to make new milk jugs.
But it is not possible (or at least not practical) to take one type of
plastic and make a different one from it. The purpose of recycling is
to be able to reuse plastic, not to chemically change it. In the case
of foam food containers, health regulations generally require them to
be made of virgin polystyrene, because safety requires knowing exactly
where the raw polystyrene came from, and that it meets Food and Drug
No common plastics liberate any toxic materials when processed
properly. You may be thinking of the recent health scare of
polycarbonate water containers containing very small amounts of
Bisphenol-A (one of the chemicals used to make polycarbonate). This
has nothing to do with heating during the molding process, but rather,
it can result if the original process to make the polycarbonate in the
first place, is not carefully controlled.
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Update: June 2012