UPLC–MS as a powerful technique for screening the nonvolatile contaminants in recycled PET

Evaluation of chemicals leached from PET and recycled PET containers into beverages

The use of recycled polyethylene terephthalate (rPET) containers, a recent shift in the beverage industry, poses new potential human health concerns including contamination from the original container; use of additives, detergents, and catalysts during recycling; and improper recycling practices. The purpose of this analysis was to evaluate available data regarding: (1) chemicals leached from PET and rPET in bottle form; (2) concentration of these chemicals; and (3) trends between rPET percent and concentration of chemicals leached. This analysis identified 211 scientific articles related to recycled plastic and leachables. Three articles met the inclusion criteria: (1) plastic was in bottle form; (2) plastic was made of PET or rPET; and (3) the study analyzed both PET and rPET using the same methods. This evaluation demonstrated that only nine compounds - benzene, styrene, acetaldehyde, 2-methyl-1,3-dioxolane, furan, bisphenol A (BPA), 2-buta-none, acetone, and limonene - have been studied. Notably, the leachable concentration of benzene, styrene, and BPA increased as the percent of recycled content increased from 0 to 100%. However, 2-methyl-1,3-dioxolane and furan implied a reverse trend, where the leachable concentration decreased as the percent of recycled content increased from 0 to 100%. The concentrations of 2-butanone, acetone, and limonene did not follow any suggested trend. Evidently, recycling PET can lead to changes in the leachables profile. This analysis further identified key areas of research, including testing a variety of liquid types, that need to be addressed to adequately conduct a human health risk assessment.

Occurrence, potential release and health risks of heavy metals in popular take-out food containers from China

Global consumption of take-out food increased rapidly and the chemicals in their containers become a potential source of human exposure. However, available information on heavy metals in the containers is extremely limited and the associated health risks remain poorly understood. We investigated Cd, Cr, Pb, Sb, Mn, Ni and Co in the popular take-out food containers from China and found the concentrations of these metals were moderate in comparison to the concentrations reported in other food contact materials. The metal concentrations in sampled containers by material type differed significantly, and higher concentrations of Cd, Pb, Sb, Mn and Co were observed in expanded polystyrene samples. The metals in the containers likely originated from intentional addition and/or contamination of materials. The potential release of the metals from containers was simulated and found the median leaching rates of Cd, Pb, Sb, Ni and Co in the range of 0.36-4.80% under typical conditions, which depended largely on the material types. Based on the observed leaching rates, we estimated that the summed carcinogenic risks of Cd, Pb, Ni and Co were unacceptable under specific exposure frequency, although the total non-carcinogenic risks from metal intake were low.

Characterization of VOCs and additives in Italian PET bottles and studies on potential functional aldehydes scavengers

This study focused on characterization of Volatile Organic Compounds (VOCs) as contaminants and non-volatile additives in Italian PET bottles, also suggesting potential functional aldehydes scavengers. Several VOCs, such as acetic aldehyde (AA), butanal, 3-methyl butanal, 1,3-dioxolane, pentanal, hexanal, octanal, 5-hepten-2-one, nonanal, and decanal, were identified by Head Space-Gas Chromatography/Mass Spectrometry (HS-GC/MS) in the PET bottles used for the packaging of six Italian brands mineral waters. AA, 1,3-dioxolane, octanal, 5-hepten-2-one, nonanal, and decanal were the most abundant compounds identified. These contaminants were also identified in the PET-bottled mineral waters. Different experiments using bottle-grade PET pellets (Btlg-PET) and PET bottles’ fragments with and without the addition of epoxidized soybean oil (ESBO) or erucamide as lubricant/plasticizer additives, poly(m-xylene adipamide) (MXD6), and/or anthranilamide (2-aminobenzamide) as potential aldehydes scavengers were carried out. Mostly VOCs observed in the PET bottles analysed were identified in a neat ESBO sample. The presence of the ESBO additive in the PET-bottle fragments was also observed by matrix-assisted laser desorption/ionization time of flight mass spectrometry analysis (MALDI–TOF MS). The ESBO sub-products were not observed in the virgin btlg-PET pellets analysed by both HS-GC/MS and MALDI–TOF MS. These results suggest that the VOCs come from an ESBO additive probably loaded during the blow-moulding processes used for the manufacturing of PET bottles. Further studies established that MXD6 (1%w), an efficient oxygen scavenger, could be also used as AA scavenger even in the presence of the commonly used anthranilamide.

The use of nanoadditives within recycled polymers for food packaging: Properties, recyclability, and safety

Nanotechnology is considered a highly valued technology to reduce the current environmental problem that is derived from plastic accumulation. The need to recycle and reuse packaging materials is essential to create a sustainable society towards a circular economy. However, the reprocessing of polymers leads to the deterioration of their characteristic mechanical, optical, thermal, and barrier properties due to the degradation of their polymeric chains. When recycled polymers are reinforced with nanoadditives, aforementioned properties improve and their use in the circular economy is more viable. In this review, different types of nanoadditives and recent advances in the development of recycled polymer nanocomposites reinforced with nanoadditives will be presented. In addition, there is a description of two research topics of current interest, recyclability of nanocomposites and safety for food packaging applications. Recyclability of nanocomposites requires a study that includes the nature of the polymer matrix, the type of polymer and the concentration of nanofiller, the morphology, the presence of additives, and the conditions of the thermal-mechanical cycles. Finally, safety section is dedicated to clarify the migration process in nanoreinforced-recycled polymers in order to assess their safety for food contact applications.