Following a rise in takeaway consumption during and after the COVID-19 pandemic, research has intensified into the chemicals and microplastics in takeaway packaging and their potential effects (FPF reported also here). As well as quantification and concerns from the sheer volume of waste (FPF reported).
Yu-Qi Huang and colleagues from South China Normal University explored the generation and environmental release of plastic waste and additives across Chinese cities, in a study published in Environmental Science and Technology in February 2024. Using online food delivery sales data from nearly 200 cities of various sizes, Huang et al. built machine learning models to predict plastic waste generation nationwide. Subsequently, researchers collected plastic takeaway packaging from ten restaurants in each of 18 Chinese cities and tested for numerous contaminants, including 21 types of phthalates, bisphenol A (BPA, CAS 80-05-7), three antioxidants and four antioxidant degradation products, Sudan I dye, an impurity in polystyrene containers, 12 organophosphate esters, and 14 brominated flame retardants. Finally, samples were combusted to measure emissions of the additives.
Antioxidants are used in a variety of consumer products, including food packaging, to prevent oxidation and prolong a product’s lifetime. When investigating antioxidants in the containers (97% of which were PP) 2,4-di-tert-butylphenol (DBP, CAS 96-76-4), a known endocrine disruptor, was found in most containers and is a potential transformation product of two antioxidants. DBP has previously been measured to migrate from infant food packaging in China (FPF reported).
The authors also discussed 2,6-di-tert-butyl-1,4-benzoquinone (BHTQ, CAS 719-22-2), found in 98% of the samples, albeit at low concentrations (0.62 μg/g). Derived from 2,6-di-tert-butyl-4-hydroxytoluene, a common phenolic antioxidant, BHTQ is more toxic than its parent compound and capable of causing DNA damage at low concentrations.
Interestingly, 40% of the containers contained Irganox 1076 (CAS 2082-79-3), an intentionally added substance, while its degradation product was found in nearly all containers and at higher concentrations (mean 0.13 μg/g and 3.85 μg/g for Irganox 1076 and its degradation product, respectively). The degradation product, 79DBOSDDD (CAS 82304-66-3) for short, is permitted for use in PP products in China but “[s]imilar results were also observed for other antioxidants, even though their uses are not allowed in PP FCMs.” The authors write that “the extensive presence of various degradation products of these additives in the plastics raises health concerns.”
A unique aspect of this study was the quantification of emissions via combustion experiments. “Based on the simulated emission factors of these additives and PAHs, approximately 51.1 tons of the additives were ultimately released from the stacks into the atmosphere via incineration of OFD [online food delivery] plastics in 2021 (45% in the gas phase and 55% in the particle phase).”
China is producing and updating many food safety standards, including food contact, in 2024; several standards concern food contact chemical migration (FPF reported).
Reference
Huang, Yu-Qi, et al. (2024). “Disposable Plastic Waste and Associated Antioxidants and Plasticizers Generated by Online Food Delivery Services in China: National Mass Inventories and Environmental Release.” Environmental Science & Technology. DOI: 10.1021/acs.est.3c06345
