In an published on January 20, 2024, in the journal Food Packaging and Shelf Life, Elena Canellas from the University of Zaragoza, Spain, and co-authors investigated the chemicals released from printed paper straws into soda, and their safety for humans. 

The researchers purchased a total of nine paper straws – printed and not printed – made in China by three different manufacturers, and performed migration experiments with a carbonated drink for 30 min at 70 °C. To analyze non-volatile migrants, they used ultra-high-pressure liquid chromatography with ion mobility quadrupole time of flight mass spectrometry (UPLC-IM-Q/TOF) which allows the identification of unknown compounds in complex samples in combination with advanced statistical analysis (principal component analysis (PCA) and orthogonal projection to latent structures discriminant analysis (OPLS-DA)). 

Canellas and co-authors detected that 19 chemicals had migrated from straws into soda samples in individual concentrations, between 0.015 and 3.6 mg chemical per kg soda. PCA demonstrated differences in migrating chemicals between the straws of the three manufacturers suggesting that they use different additives in their production. For instance, the photoinitiators 2,2-dimethoxy-2-phenylacetophenone (CAS 24650-42-8) and diphenyl (2,4,6-trimethylbenzoyl)phosphine oxide (CAS 75980-60-8), and the dye, rhodamine B (CAS 81-88-9), were three compounds found to migrate from some of the printed straws. Many of the migrating compounds “were additives typically found in plastic products.”  

The scientists were further interested in whether the migrating levels could be considered safe. Currently, Europe has no harmonized regulation specific to paper, board, inks, and coatings as food contact materials, but some national regulations exist in France, the Netherlands, Germany, and elsewhere. Due to the absence of a harmonized European regulation, Canellas et al. compared their findings to the specific migration limits (SMLs) established for plastic food contact materials (Regulation (EU) No 10/2011), finding that migration of the primary aromatic amine and suspected carcinogen 4,4’-methylenedianiline (CAS 101-77-9) exceeded its regulatory SML. In addition, two recognized endocrine disrupting chemicals (EDCs), bis(2-ethylbutyl)phthalate (CAS 7299-89-0) and dioctyl phthalate (CAS 117-84-0), were among the migrating compounds.   

The authors concluded this “suggest[s] that paper straws may not be the safest alternative to plastic straws in terms of food safety.” 

banned many single-use plastic products in the EU from 2021, including plastic drinking straws (FPF reported), leading many manufacturers to produce paper drinking straws as an alternative. In 2019, the Swiss government laboratory tested 12 paper straws and found them to contain chloropropanols, mineral oils, and photoinitiators (FPF reported). Besides a safety challenge, paper straws are also considered a recycling challenge, according to McDonald’s (FPF reported). Straws labeled as “plant-based”, and “biodegradable” do not seem better according to a study that detected per- and polyfluoroalkyl substances (PFAS) in 36 out of the 38 tested products (FPF reported). 

 

Reference 

Baker, B. H. et al. (2024). “.” Food Packaging and Shelf Life. DOI: 10.1016/j.fpsl.2024.101237