PLASTICS AND HEALTH IMPACTS - Plastics and Environmental Sustainability - page 363

industry-sponsored study estimated the food-related exposure to be 6.6 µg/
person/day. All these values, however, are well below the generally accepted
tolerable or “safe” levels proposed for styrene. The WHO reported (WHO,
2003) a tolerable daily intake (TDI) of 7.7 (µg/kg bw/day) or 0.46 mg/
person/day for a 60 kg individual. The REACH regulations in EU proposed
(IUCLID, 2013) a derived no effect levels (DNELs) for long-term exposure
for styrene of 2.1 (mg/kg bw/day). Safe levels established for chemicals are
often based on limited experimentation (as with ED chemicals discussed
in Chapter 7 ), and these may be revised as more information emerges as
to different modes of toxicity. Given the possible carcinogenicity associated
with styrene, a precautionary stance is reasonable.
8.3.2 Leachate from PET Bottles
The polyester PET was reported to have 4,024-11,576 mg/kg of extractible
material (Kim and Lee, 2012b) consisting mainly of cyclic oligomers along
with 1.3-2.8% of linear oligomer. Terephthalic acid (TPA), hydroxyethyl
terephthalates, and bis -hydroxyethyl terephthalate were also found at levels
of 3.0-28.2 mg/kg, 16.8-118.2 mg/kg, and 3.9-26.7 mg/kg, respectively.
However, these were extracted using organic solvent mixtures and are
generally not extractible by aqueous food or beverage.
In studies with nonfatty food simulants in contact with PET, the leachate at
40°C over 10 days was only 0-0.94 µg/dm 2 , and with fatty food simulant, 8
0.36-1.05 µg/dm 2 of cyclic oligomer leached at 20°C over 48 h of contact
(Kim and Lee, 2012a). Migration of the three monomers (TPA, IPA, and
DMT) 9 into food simulants (water, 4% acetic acid, 20% alcohol, and
n -heptane) from 56 PET containers collected from open markets showed no
extracted monomer at a detection level of 0.1 ppm (Park et al., 2008). The
TDI associated with this level of migrants is well below the accepted safety
levels. Values for water extracts of migrants reported in different studies
vary widely because of differences in experimental conditions, specifically
the duration of contact or storage, temperature, and pH of contents as well
as the standard test protocol used (Kim and Lee, 2012a). The published
data does not support a precautionary stance for the use of PET in beverage
bottle or in other food-contact applications.