European survey on post-consumer poly(ethylene terephthalate) (PET) materials to determine contamination levels and maximum consumer exposure from food packages made from recycled PET

Abstract

Typical contamination and the frequency of misuse of poly(ethylene terephthalate) (PET) bottles are crucial parameters in the risk assessment of post-consumer recycled (PCR) PET intended for bottle-to-bottle recycling for direct food contact applications. Owing to the fact that misuse of PET bottles is a rare event, sustainable knowledge about the average concentration of hazardous compounds in PCR PET is accessible only by the screening of large numbers of samples. In order to establish average levels of contaminants in PET source materials for recycling, PET flakes from commercial washing plants (689 samples), reprocessed pellets (38) and super-clean pellets (217) were collected from 12 European countries between 1997 and 2001. Analysis of these materials by headspace gas chromatography revealed average and maximum levels in PCR PET of 18.6 and 86.0 mg kg-1 for acetaldehyde and 2.9 and 20 mg kg-1 for limonene, respectively. Acetaldehyde and limonene are typical compounds derived from PET itself and from prior PET bottle contents (flavouring components), respectively. Maximum levels in PCR PET of real contaminants such as misuse chemicals like solvents ranged from 1.4 to 2.7 mg kg-1, and statistically were shown to result from 0.03 to 0.04% of recollected PET bottles that had been misused. Based on a principal component analysis of the experimental data, the impact of the recollecting system and the European Union Member State where the post-consumer PET bottles had been collected on the nature and extent of adventitious contaminants was not significant. Under consideration of the cleaning efficiency of super-clean processes as well as migration from the bottle wall into food, it can be concluded that the consumer will be exposed at maximum to levels < 50 ng total misuse chemicals day-1. Therefore, PCR PET materials and articles produced by modern superclean technologies can be considered to be safe in direct food applications in the same way as virgin food-grade PET.

Contaminantes voláteis provenientes de embalagens plásticas: desenvolvimento e validação de métodos analíticos

“…13 Todos esses compostos têm sido relatados como contaminantes, especialmente em embalagens PET (politereftalato de etila) pós-consumo. [13][14][15] Diversos métodos têm sido propostos para o tratamento de reciclados com enfoque nas preocupações relacionadas aos resíduos de contaminantes que podem estar presentes nos materiais pós-consumo. Alguns aspectos envolvem a obtenção de informação sobre a procedência do material pós-consumo, processos de seleção de materiais, tecnologias de descontaminação, obtenção de informação sobre os níveis de contaminação em plásticos pós-consumo antes e após os processos de descontaminação.…”

“…Esta técnica é conhecida por análise do headspace. 15,29,37,38 As variações mais conhecidas desta técnica incluem o método do headspace estático e o método do headspace dinâmico (purge-and-trap). 33,39 No modo estático, a amostra é armazenada e selada em um frasco hermético e os analitos voláteis são coletados no headspace do frasco após equilíbrio de volatilização.…”

A method to determine volatile contaminants in polyethylene terephthalate (PET) packages by HDC-GC-FID and its application to post-consumer materials

“…Modern super washing methods include a final extrusion step followed by Solid State Post-condensation (SSP) that increases the intrinsic viscosity of the polymer and also promotes its decontamination since the material is submitted to high temperatures (ca. 225 °C) and high vacuum in this step (FRANZ;MAUER;WELLE, 2004;FRANZ;WELLE, 2002). After this last process, the recycled product is comparable to the virgin material, and its application in packaging for direct contact with foods can be considered viable.…”

“…Currently, the most used extraction systems involve headspace analysis. There are many variations to this analytical technique such as the direct analysis of the headspace, and static and dynamic concentration of the headspace using traps consisting of porous polymers, especially tenax (FRANZ;MAUER;WELLE, 2004;van WILLIGE et al, 2003;KALJURAND;SMIT, 1994;HAKKARAINEN;GRONING;ALBERTSSON, 2003;SOTO-VALDEZ;GRAMSHAW;VANDENGURG, 1997;NIELSEN, 2005;NONGONIERMA et al, 2006). Recent advances include automatic systems that allow the coupling of the headspace sampler to the gas chromatograph injector, known as the purge and trap injection system (LEBOSSÉ; DUCRUET; FEIGENBAUM, 1997;WEZL;LANKMAYR, 2002;REYNIER et al, 2004;VILLBERG;VEIJANEN;GUSTAFSSON, 1998;KALJURAND;SMIT, 1994).…”

Determination of volatile organic compounds in recycled polyethylene terephthalate and high-density polyethylene by headspace solid phase microextraction gas chromatography mass spectrometry to evaluate the efficiency of recycling processes

“…Since the measurement of contaminants in every packaging material is impossible, challenge tests have been developed in which surrogate chemicals are artificially introduced into a recycling process. As a safety parameter or as a criterion for cleaning efficiency, a migration limit of 10 g L −1 surrogate into food from a packaging material produced in a challenged recycling process has been generally accepted [3,[11][12][13].…”