Polyphenylsulfone (PPSU) for baby bottles: a comprehensive assessment on polymer-related non-intentionally added substances (NIAS)

ABSTRACT

Polyphenylsulfone (PPSU) is a new material for the production of baby bottles. PPSU is a polyether plastic formally composed of bisphenol S (BPS) and 4,4ʹ-dihydroxybiphenyl (DHBP), which both have slight endocrine activities in in vitro tests. So far, little is known about the presence and the release of potentially hazardous substances from PPSU baby bottles. In this study, we present a three-step approach for the analysis of PPSU starting with polymer characterisation in terms of chemical structure, total oligomer content and hydrolytic stability. Second is the determination of extractables focussing on monomers, monomer derivatives, linear and cyclic oligomers below 1000 Da and residual solvent. Third is a risk assessment on migration-related substances in accordance to European Union plastics regulation no. 10/2011 based on triplicate consecutive migration experiments using official milk simulant 50% ethanol. We analysed five types of PPSU baby bottles from different brands as well as corresponding raw materials from different manufacturers by various analytical techniques (high-performance liquid chromatography (HPLC)-diode array detector /fluorescence detector/Corona/electrospray ionisation-MS, HPLC-size exclusion chromatography, gas chromatography-mass spectrometry (GC-MS), ¹H-NMR). We found significant variations of PPSU materials from different producers with regard to polymer and oligomer chain end groups (methoxylation, chlorination), while total oligomer content below 1000 Da was similar (mean about 0.48%). BPS was not detected above 0.3 mg/kg polymer in any PPSU sample. Residual DHBP content ranged between 1.7 and 15.5 mg/kg polymer. The most common oligomer in all PPSU samples was the cyclic tetramer (about 1200 mg/kg polymer), which is the only cyclic compound below 1000 Da. Residual solvent, sulfolane, was determined to a maximum of 1300 mg/kg polymer. In migration tests, we detected exceedances of neither specific migration limits for listed substances nor of thresholds of toxicological concern for non-listed substances (monomer derivatives, oligomers). Based on our analytical results, no concerns exist regarding migration of polymer-related substances from PPSU baby bottles.

GRAPHICAL ABSTRACT

KEYWORDS:

• Polyphenylsulfone
• PPSU
• baby bottles
• NIAS assessment
• bisphenol S (BPS)
• oligomers

Acknowledgements

The authors thank Prof. Thomas Henle and especially Sophia Witte for the possibility of performing HPLC-MS measurements.

Disclosure statement

No potential conflict of interest was reported by the authors.