An article published on April 2, 2018, in the peer-reviewed journal Food Additives & Contaminants: Part A, reported on the assessment of non-intentionally added substances (NIAS) in polyphenylsulfone (PPSU) polymer intended for baby bottles. PPSU is “a polyether plastic formally composed of bisphenol S (BPS, CAS 80-09-1) and 4,4’-dihydroxybiphenyl (DHBP, CAS 92-88-6), which both have slight endocrine activities in in vitro tests.”

Martin Eckardt and colleagues from the Food Chemistry and Food and Skin Contact Materials, Technische Universität Dresden, Dresden, Germany, analyzed “five types of PPSU baby bottles from different brands as well as corresponding raw materials from different manufacturers.” Their approach followed three steps, namely (1) determination of “chemical structure, total oligomer content and hydrolytic stability” of the polymer, (2) “determination of extractables focusing on monomers, monomer derivatives, linear and cyclic oligomers below 1,000 Da and residual solvent,” and (3) “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” for two hours at 70 °C.

Different PPSU samples showed “significant variations . . . with regard to polymer and oligomer chain end groups (methoxylation, chlorination),” but “total oligomer content below 1000 Da was similar (mean about 0.48%).” The cyclic tetramer was the most abundant oligomer, reaching about 1200 mg/kg polymer in all PPSU samples. Concentration of BPS in all samples was below 0.3 mg/kg polymer, while DHBP residues “ranged between 1.7 and 15.5 mg/kg polymer.” In addition, residual solvent sulfolane (CAS 126-33-0) was determined at the concentrations up to 1300 mg/kg polymer. Migration tests did not show any exceedance of specific migration limits “neither . . . for listed substances nor for thresholds of toxicological concern for non-listed substances (monomer derivatives, oligomers).” Therefore, the authors conclude that “no concerns exist regarding migration of polymer-related substances from PPSU baby bottles.”


Eckardt, M., et al. (2018). “Polyphenylsulfone (PPSU) for baby bottles: a comprehensive assessment on polymer-related non-intentionally added substances (NIAS).Food Additives & Contaminants: Part A 35:1421-1437.