Three recent studies have examined synthetic antioxidants in Chinese food packaging and their migration to food simulants. Synthetic antioxidants are commonly used to inhibit the oxidation of polymers and other polymeric materials, such as cured printing inks, thereby slowing their aging process. Widely used antioxidants include synthetic phenolic antioxidants and organophosphite antioxidants, which are frequently present in food contact materials (FCMs) (FPF reported, also here). Some of these chemicals have been linked to adverse health effects, such as endocrine disruption or reproductive toxicity.
In the first study, Xiaomeng Ji from Shandong University in Qingdao, China, and co-authors analyzed synthetic antioxidants in 50 food and food packaging samples from a local market. All samples had outer printed paperboard packaging and inner plastic packaging in direct contact with dry food. Synthetic phenolic antioxidants and organophosphite antioxidants were analyzed using gas and liquid chromatography – mass spectrometry.
The study found that the outer packaging, inner packaging, and packaged food, were quite different in terms of antioxidant content. The outer printed paperboard packaging contained a median of 5 mg/kg synthetic antioxidants, mainly tris(2,4-di-tert-butylphenyl) phosphate (AO168=O, CAS 95906-11-9), 4-tert-octylphenol (4-tOP, CAS 140-66-9), butylated hydroxytoluene (BHT, CAS 128-37-0), and its degradation products. The inner plastic packaging contained a median of 24 mg/kg synthetic antioxidants, mainly tris(2,4-di-tert-butylphenyl) phosphite (AO168, CAS 31570-04-4), AO168=O, and 2,4-di-tert-butylphenol (2,4-DtBP, CAS 96-76-4).
Several antioxidants were present in both the inner packaging and the food, suggesting migration from the FCM as their source in the food. In the packaged dry food, 5 mg/kg of synthetic antioxidants were present, with AO168=O, BHT, and its oxidation product BHT-OH (CAS 88-26-6) being the most abundant. However, for several antioxidants, “no correlation was found […], indicating other sources”. The authors suggest contamination during processing or direct use as food additives as the most likely sources. They also argue that migration to other types of foods or under different storage conditions would likely be higher.
Some of the detected antioxidants are highly hazardous: 4-tOP is an endocrine disruptor and reproductive toxicant; BHT and 2.4-DtBP are both suspected endocrine disruptors.
The second study by Bin Han and colleagues from Huazhong University of Science and Technology in Wuhan examined the presence and migration of synthetic phenolic antioxidants in 118 takeaway food contact materials. Most of the samples were made of plastics. They were found to contain between 0.04 to 69 mg/kg (median 2 mg/kg) synthetic phenolic antioxidants. Predominantly 2,4-DtBP (potentially endocrine disrupting) and 2,6-di-tert-butylphenol (2,6-DtBP, CAS 128-39-2), and 2,6-di-tert-butyl-1,4-benzoquinone (BHTQ, CAS 719-22-2), a degradation product of BHT, were present. A previous study found that 98% of samples from takeaway packaging in China contained BHT-Q (FPF reported). In the current study, 2,4-DtBP dominated migration and exposure. Han et al. estimate that takeaway food packaging contributes 17.56 ng/kg bodyweight (bw)/day to the total exposure to synthetic phenolic antioxidants, which is twice the exposure from indoor dust and personal care products. The authors conclude that “human exposure to [synthetic phenolic antioxidants] occurs primarily through food intake”.
In a third study, Ruize Zhou and colleagues from the China Agricultural University in Beijing investigated organophosphite antioxidants in 99 takeaway foods and 50 food packaging samples. The major antioxidants found in the food packaging were AO168 (mean: 8 mg/kg) and AO168=O (mean: 2 mg/kg), which mainly migrated to fatty foods. The average dietary intake was estimated at 465 ng/kg bw/day, dominated by AO168O. Plastic-packaged takeaway food contributed the most to the estimated daily intake, compared to other packaging materials like aluminum and paper.
All three studies highlight the widespread presence and diversity of synthetic antioxidants in Chinese food packaging. The most commonly found organophosphite antioxidants were AO168 and AO168=O. The most common synthetic phenolic antioxidants were BHT and its degradation products, di-tert-butylphenols, and 4-tert-octylphenol, some of which are known or suspected endocrine disruptors.
According to the authors of all studies, some uncertainties regarding migration, the estimated dietary intake, and risk assessment remain. Xiaomeng Ji and co-authors write that “current no-observed adverse effect levels (NOAEL) for several [antioxidants], such as [2,4-DtBP], failed to take into account their potential as suspected endocrine disrupters”. Bin Han and co-authors point out that the mixture effects of chemicals migrating from food contact materials should be considered. Ruize Zhou and colleagues suggest continued monitoring of emerging antioxidants and other contaminants particularly in takeaway food packaging to ensure food safety.
References
Ji, X., et al. (2024).’ The hidden diet: Synthetic antioxidants in packaged food and their impact on human exposure and health’. Environment International. DOI: 10.1016/J.ENVINT.2024.108613
Han, B., et al. (2024). ‘Prevalence of synthetic phenolic antioxidants in food contact materials from China and their implications for human dietary exposure through take-away food’. Journal of Hazardous Materials. DOI: 10.1016/j.jhazmat.2024.134599
Zhou, R., et al. (2024). ‘Emerging organophosphite and organophosphate esters in takeaway food and the implications for human exposure’. Environmental Science and Pollution Research. DOI: 10.1007/S11356-024-33413-8
Other recent studies
Petrulionienė, T., et al. (2024). ‘Validation and Application of an LC–MS/MS Method for the Determination of Antioxidants Originating from Commercial Polyethylene Packages and their Migration into Food Simulants’. Food Analytical Methods.
DOI: 10.1007/S12161-024-02631-8
Wu, X. et al. (2024). ‘Chlorinated paraffins in takeout food and its packaging in Beijing, China and dietary exposure risk’. Environmental Research. DOI: 10.1016/j.envres.2024.118768
Li, W., et al. (2024). ‘Exploring organophosphate ester contamination and distribution in food: A meta-analysis’. Food Chemistry. DOI: 10.1016/j.foodchem.2024.140035
