EDCs and PET Bottles

Worldwide production of APEs is about 390,000 tons, and about 80% of it is used to produce octyl- or nonylphenol ethoxylate (NPE) nonionic surfactants. About 10% of it is used in manufacturing phosphite antioxidants (tris(4-nonyl-phenyl) phosphite used in rubber and plastics compounds. The stabilizers and plasticizers based on NP are also used in plastics intended for food-contact applications. They are not highly persistent chemicals and once discharged into the environment, APEs rapidly hydrolyze into alkylphenols that are subsequently slowly biodegraded by microorganisms. The USEPA criteria concentrations for freshwater NP exposure is CMC = 28 acute-pg/1 and CCC = 6.6 chronic-pg/l aquatic community might be exposed to CMC concentration only briefly and CCC concentration indefinitely. The corresponding numbers for saltwater are 7.0pg/l 1.7pg/l. 

Generally, APEs are much less potent EDCs compared to those previously discussed. In vitro binding affinity of APEs to the receptors is much lower (4 orders of magnitude smaller) compared to estradiol. No data from human studies are available on ED effects of APEs. 

Water and carbonated beverage bottles are made predominantly from poly(ethylene terephthalate) (PET). The polymer is made by condensation reaction of ethylene glycol with either terephthalic acid or its dimethyl ester. The process in practice includes three steps prepolymer formation, melt condensation to increase viscosity, and solid-state polymerization at 180-230°C to yield a resin with an average molecular weight that is high enough for use as bottle resins. Antimony trioxide is used as a catalyst in polymerization (Duh, 2002). 

Recent reports, however, claim PET-bottled water and beverages to show, albeit very mild, but definitive ED activity (Sax, 2010). The effect, however, is inconsistent (Ceretti et al., 2010 Quart et al., 2011) and not seen in all bottles tested in a given study (Wagner and Oehtmann, 2009, 2011) and in bottles purchased at retail stores (Pinto and Reali, 2009). The estimated exposure to EDCs via this route, however, is very low (a pg to a ng estradiol per day (Kereszteset al., 2009)). 

Exposure of PET bottles filled with water to sunlight over extended durations is reported to result in accumulating degradation products on the outer layer of the bottle. These include PET monomer and dimer. However, over extended exposure period of up to 126days, no degradation products were detected in the bottles (Wegelin et al., 2001). 

---