In an article published online on August 17, 2021, in the peer-reviewed journal Environmental Science and Technology, Lisa Zimmermann and co-authors from the Goethe University and the Institute for Social-Ecological Research in Frankfurt am Main, Germany, as well as the Norwegian University of Science and Technology, Trondheim, Norway, reported on the chemicals migrating from 24 consumer plastics and their in vitro toxicity.
In a publication in 2018, the scientists demonstrated that methanolic extracts of plastics contain a wide variety of chemicals and are toxic in vitro (FPF reported). As a follow-up, their current study aimed to find out whether these mixtures also leach under realistic use. To this aim, they performed migration experiments with water according to EU regulation’s experimental standards on plastic food contact materials (FCMs) and analyzed the migrates with four in vitro bioassays and nontarget high-resolution mass spectrometry (UPLC-QTOF-MSE).
The study results showed that all 24 samples induced baseline toxicity, 22 activated an oxidative stress response, 13 contained antiandrogenic compounds, and one sample contained estrogenic compounds. Comparing the eight different polymer types, including petroleum- and bio-based products, demonstrated that chemicals migrating from polyvinyl chloride (PVC) and polyurethane (PUR) articles were highly toxic. However, toxicity levels varied within one polymer type leading the authors to conclude that “the toxicity migrating from plastics is specific to the product rather than the polymer type.” A comparison of the 12 FCMs with the 12 non-FCMs further showed that FCMs, although mores strictly regulated, have a similar potential to induce oxidative stress and baseline toxicity as non-FCMs. According to the article, this “underpins concerns over the adequacy of the traditional approach of assessing the safety of FCMs that prescribes to assess the migration of starting substances.” Moreover, Zimmermann and colleagues compared the effects of migrates to the effects of methanolic extracts analyzed in their previous study. They found that the chemical mixtures migrating into water are generally less toxic than those extractable with methanol. However, some migrate samples induced a greater toxic effect than their corresponding extract.
The number of chemical features that readily migrated from an individual plastic product or were newly formed in the migrate, ranged from 17 to 8681. This corresponds to 1 to 88 % of all features associated with the respective plastic product. While the number of leaching chemicals varied with the products, half of the migrates contained more than 2000 compounds. Of all unique chemical features present in migrate and extract samples together, around 8% were tentatively identified by comparison with the database of Chemicals associated with Plastic Packaging (CPPdb; FPF reported), the NORMAN Suspect List Exchange (NORMANdb), and the chemicals registered under REACH (ECHAdb). The identified compounds included plastic additives such as organophosphates, the processing aid pentaethylene glycol (CAS 4792-15-8), the solvent solketal (CAS 100-79-8), and the adhesive mono(2-acryloyloxyethyl) succinate (CAS 50940-49-3). The latter compound is listed in the Food Packaging Forum’s Food Contact Chemicals database (FCCdb) as a substance of potential concern due to predicted health hazards.
The authors emphasized that their study does not allow one to draw conclusions on human health impacts since actual exposure levels and in vivo toxicities remain to be determined. However, the results highlight that “many more chemicals are migrating from plastics than previously known”, most of which are unidentified. This “pinpoints the shortcomings of current scientific and regulatory approaches to the chemicals leaching from plastics” which can be a relevant exposure source of humans to chemicals. To address regulatory gaps and work towards assessing actual health hazards of plastics, the scientists proposed combining whole migrate toxicity testing and nontarget chemical analysis. Furthermore, they emphasized that manufacturers could contribute to an improved chemical safety of plastics by reducing the number of compounds they use.
Reference
Zimmermann, L., et al. (2021). “Plastic products leach chemicals that induce in vitro toxicity under realistic use conditions.” Environmental Science and Technology. DOI: 10.1021/acs.est.1c01103
