Environmental Engineering Reference
In-Depth Information
plasticizer). It advocates avoiding PS (which can leach residual styrene) and
PC (which can leach BPA) plastics as well, with any food-contact products.
A 2011 study by Lithner et al. (2011) assessed the environmental and health
hazards posed by plastics, based on the toxicity of their monomers. The
classification is not inherent to the polymer as it is based primarily on
residual monomer (with selected additives, plasticizer, and flame
retardants). The ranking (see
Table 8.8
) can have relevance only for
occupational exposures and in some food-contact uses of plastics. Also,
future advances in residual monomer reduction technology and green
substitution of additives can change the status of a polymer in this
assessment. Where “recyclability” is used as a ranking criterion, it generally
refers to technical recyclability that has little to do with if the resin will in
fact be recycled in practice.
Table 8.8
Hazard Levels of Common Plastics Estimated from
Monomer Characteristics
Source: Data based on Lithner et al. (2011).
Rank Plastic material
Rank Plastic material
V
Flexible PU foam
IV
Phenol-formaldehyde resin
Plasticized PVC
(worst)
Unsaturated polyester (with MMA)
Rigid PVC
Polycarbonate (PC)
Rigid PU foam
Unsaturated polyester (with
styrene)
Plasticized PVC
Poly(methyl methacrylate)
High-impact PS
(HIPS)
Thermoplastic polyurethane
III
Nylons
II
LDPE, LLDPE, HDPE
Expanded PS foam
PET
I
PP
Endocrine disruptor effect was not taken into account here; otherwise, PC would
possibly be considered more hazardous (Rank V).
While there is some justification for using such rankings as a general guide
to material selection, there are shortcomings in the approach. The most