Polyethylene terephthalate food-product containers made with post-consumer materials have been found contaminated with heavy metals due to the recycling and sorting process. The increased use of recycled plastic flake from international suppliers, and subsequent commingling with electronic waste, has been suspected as the source of the increased levels of heavy metal contamination. In this study, nickel, chromium, cadmium, antimony, and lead were quantified in post-consumer polyethylene terephthalate extruded sheet and thermoformed samples, using inductively coupled plasma-atomic emission spectrometry. Recycled polyethylene terephthalate samples were digested using trace-metal grade hydrochloric, perchloric, and nitric acids. Samples were analyzed per ASTM E1613-04, standard test method for determination of lead by inductively coupled plasma atomic emission spectrometry, flame atomic absorption spectrometry, or graphite furnace atomic absorption spectrometry techniques. Two hundred samples were tested of which 29 were found to be contaminated with heavy metals. Chromium and cadmium were found in all 29 sample replicates. Nickel was found in 96.4% of the sample replicates and when it was found, the concentration averaged 11.59 ppm. Lead was found in 90.4% of the sample replicates and the average concentration was 0.15 ppm. Antimony was found in 97.6% of the sample replicates and concentrations were higher in rigid recycled polyethylene terephthalate containers compared to films. It was noted that the total contamination in all 29 samples was well below the threshold level set for the incidental presence of heavy metals in packaging materials as set forth in California’s Toxics in Packaging Prevention Act of 2006. The percentage of each heavy metal that would actually leach from the plastics to contaminate food products during normal processing, packaging, marketing, and consumer use was not determined in this study.
CurtzwilerGVorstKDanesJE. Effect of recycled poly(ethylene terephthalate) content on properties of extruded poly(ethylene terephthalate) sheets. J Plas Film Sheeting2011; 27(1–2): 65–86.
3.
KangDHAurasRVorstK. An exploratory model for predicting post-consumer recycled PET content in PET sheets. Polym Test2011; 30(1): 60–68.
4.
PerringLAlonsoMAndreyD. An evaluation of analytical techniques for determination of lead, cadmium, chromium, and mercury in food-packaging materials. Fresenius J Anal Chem2001; 370(1): 76–81.
5.
VergnaudJM. Problems encountered for food safety with polymer packages: Chemical exchange, recycling. Advances in Colloid and Interface Science1998; 78(13): 267–297.
6.
JarupL. Hazards of heavy metal contamination. Br Med Bull2003; 68: 167–182.
Office of Environmental Health Hazard Assessment, California. No significant risk levels (NSRLS) for the Proposition 65 carcinogens lead and lead compounds (oral). Reproductive and Cancer Hazard Assessment Section, Office of Environmental Health Hazard Assessment (OEHHA), California Environmental Protection Agency 2001. http://www.oehha.ca.gov/prop65/law/pdf_zip/Lead_oralNSRL.pdf (accessed 18 October 2011).
ASTM Standard E1613-04, 2011. Standard test method for determination of lead by inductively coupled plasma atomic emission spectrometry (ICP-AES), flame atomic absorption spectrometry (FAAS), or graphite furnace atomic absorption spectrometry (GFAAS) techniques. 2003. West Conshohocken, PA: ASTM International. DOI: 10.1520/E1613-04, www.astm.org.
12.
HynesMJJonsonB. Lead, glass and the environment. Chem Soc Rev1997; 26(2): 133–146.
