Polyhydroxyalkanoates as Packaging Materials: Current Applications and Future Prospects - Polyhydroxyalkanoate (PHA) Based Blends, Composites and Nanocomposites - page 189

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Figure 8.2 Graph showing the change in environmental concentrations of PHAs
from different environments sampled in New South Wales, Australia.

The potential of PHAs as biodegradable replacements for conventional bulk
commodity plastic packaging while promoting sustainable development has
long been recognised. 36 However, despite a body of research reporting their
environmental degradation, there is comparatively little data on their en-
vironmental occurrence. 36-40 While the biota from and in environmental
samples can be induced to synthesise significant concentrations of PHAs—up
to 90% of their cellular dry weight—'natural' concentrations of PHAs are
significantly lower. 37-41 In their research measuring environmental PHA
concentrations in sediment, Findlay and White (1983) speculated that PHAs
might be used to elucidate the nutrient history of the sampling environ-
ment. 42 Similarly, Foster et al. measured PHA concentrations in soils and
sediment samples from pristine environments and those known to have
undergone recent pollution (Figure 8.2). 43 Their research showed background
levels of PHAs of 0.12 to 0.40 mg g 1 in soil from unpolluted environments
characterised by agricultural land or native vegetation. In contrast, PHAs in
samples affected by anthropogenic activity displayed concentrations 14 to 40
times higher. The ubiquitous presence of PHAs, as determined in a variety of
environments, is supportive of their development as bioplastics for environ-
mentally-friendly, biodegradable packaging. 43

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8.4.1 Commercial PHA Packaging
The potential of PHAs for truly biodegradable packaging was recognised in
the 1980s with the commercial release of Biopol s , thermoplastic resins of
P(3HB) with various copolymer loadings of (3HV), by Imperial Chemical
Industries (ICI, now Zeneca). The biodegradability of PHAs stems from the
fact that PHAs will break down 'fully' to water and carbon dioxide. The en-
vironmentally-friendly impact of PHAs also stems from their microbially