An article published on December 5, 2018, in the peer-reviewed journal PLoS One, reported on the chemical migration from plastic food contact articles (FCAs) “collected from the Chinese national product supervisory inspection from 2016 to 2017.” The study was performed by Shasha Qian and colleagues from the Nanjing Institute of Supervision & Testing on Product Quality, National Supervision & Testing Centre for Food & Food Additives, Jiangsu Center of Supervision & Testing on Green Degradable Material Quality, Nanjing, China.
Migration experiments were carried out using hexane as food simulant and following the procedures outlined in the Chinese guideline GB5009.156. First, several target compounds were quantified to examine compliance with regulatory specific migration limits (SML). Then, a detailed analysis of “unknown chemical migrants” by gas chromatography-mass spectrometry (GC-MS) was performed in 120 samples randomly picked from the pool of generally-compliant products, i.e., products with an overall migration below 10 mg/dm2 and migration of target contaminants below their respective specific migration limits. These samples “covered all authorized categories of plastic FCM [(food contact material)] products in China, including bottles, disposable plastic tableware, plastic drink bottles, plastic wrap bags, packing bags” and others, the authors summarized. The FCMs analyzed included “poly(ethylene terephthalate) (PET), polyethylene (PE), polycarbonate (PC), polypropylene (PP), low-density polyethylene plastics (LDPE), melamine-formaldehyde (MF), polystyrene (PS) and biaxially oriented polypropylene/low density polyethylene (BOPP/LDPE).”
The analyzed chromatograms revealed “dozens or hundreds of different components,” the authors informed. Among these, the scientists were able to identify “nearly 100” compounds, of which “only 13% [were] included in the permitted list of Commission Regulation EU No 10/2011.” This means that “most of the identified migrants were not imposed to safety evaluation tests,” the authors noted. The authors classified all detected migrants into “11 categories: alkanes, amides, esters, alcohols, alkenes, acids, phenols, siloxanes, aldehydes, ethers and other substances” and summarized that “the alkane and phenolic substances were found almost in all FCM products.” PET products showed a “significantly lower” amount of migrating chemical substances compared to other materials. The substance squalene (CAS 111-02-4) was found only in the PP material.
The authors further retrieved the “toxicology data of all chemicals” and observed that “most substances were of low toxicity.” The three “chemicals of concern” highlighted by the authors were bis(2-ethylhexyl) adipate (DEHA, CAS 103-23-1), bis(2-ethylhexyl) phthalate (DEHP, CAS 117-81-7), and stearamide (CAS 124-26-5). Subsequently, a quantitative analysis was performed for these three substances. The substance 2,4-di-tert-butylphenol (2,4-DTBP, CAS 96-76-4) was also quantified, despite “not [being] involved in any priority list,” because it was found “in all types of FCM” analyzed. This compound is “widely used as an intermediate for the preparation of antioxidants, UV stabilizers and in manufacturing of pharmaceuticals and fragrances,” the authors summarized.
The detected concentrations of DEHA and DEHP were below their respective SMLs of 18 mg/kg and 1.5 mg/kg. DEHA was namely detected in three types of FCMs, PP, BOPP/LDPE, and PE, at 3.32±0.59, 3.51±1.02 and 3.78±0.21 mg/kg, respectively. DEHP was detected in all FCMs except for PET and PS, with the highest concentration of 0.29±0.03 mg/kg detected in PP products, followed by BOPP/LDPE (0.24±0.02 mg/kg), PC (0.24±0.01 mg/kg), and PE (0.17±0.00 mg/kg) products. MF products had very low DEHP concentrations of 0.01±0.00 mg/kg.
Stearamide was also “under the recommended limit” of 60 mg/kg with the three FCMs having detectable concentrations being BOPP/LDPE (39.76±17.39 mg/kg), PE (20.57±13.27 mg/kg), and PP(14.07±1.64 mg/kg).
2,4-DTBP could be quantified in all analyzed FCMs except MF. The highest level was seen in BOPP/LDPE products (45.57±31.51 mg/kg), followed by PE (25.56±22.21 mg/kg), PS (3.91±1.67 mg/kg), PP (2.43±0.82 mg/kg), PET (1.34±0.35 mg/kg), and PC (1.26±0.39 mg/kg) products.
The authors concluded that their results imply “that plastic FCMs . . . [are] not so ‘inert’ as they [are] usually considered, and further safety evaluation should be performed toward the complete identification of new substances in FCM products.”
Qian, S., et al. (2018). “Detection and quantification analysis of chemical migrants in plastic food contact products.” PLoS One 13(12): e0208467.