Environmental Engineering Reference
In-Depth Information
a. Catalyst residues, residual monomer (e.g., BPA, styrene, and vinyl
chloride (VC)), and very-low-molecular-weight oligomers present in the
plastic resin from polymerization process (Bomfim et al., 2011)
b. Additives (such as phthalates, antioxidant, slip agents) deliberately
added to the plastic during compounding and its processing into useful
products (Bonini et al., 2008)
c. Products from degradation of the polymer or its additives on exposure
to heat or solar ultraviolet radiation yielding toxic products
d. Organic chemicals picked up from the environment (air, water, or
contents in a package) and concentrated in the polymer through
partition
The items (c) and (d) are also referred to as “unintentionally added
substances” in plastics. All these chemicals remain dissolved in the plastic
matrix. Being not covalently bonded to the polymer molecules, these can
leach out of the plastic and in the case of food-contact plastics present a
source of contamination of the food. It is important to realize, however, that
such migration in most instances results in very low levels of the chemicals
in the food, often too low to have any observable adverse effect. But with
someclassesofcompounds,suchastheEDsdiscussedin
Chapter7
,thiscan
still be a concern.
The functional additives that are commonly employed in plastics food
packaging are listed in
Table 8.4
(Singh et al., 2012).
