The Verdict List

Ingredient glossary

Depends on context

PPSU (polyphenylsulfone)

Last reviewed

Researched & reviewed by The Verdict List Editorial Team

What it is

PPSU is a high-performance amber plastic used for premium baby-bottle bodies because it tolerates high heat, holds its shape and resists shattering. It is not the polycarbonate that was made with BPA.

Why it's flagged

The 2018 study below describes PPSU as formally composed of bisphenol S (BPS) and 4,4'-dihydroxybiphenyl (DHBP), both of which showed slight endocrine activity in in-vitro tests, so its chemistry is not unrelated to bisphenols. In five PPSU baby-bottle types it did not detect BPS above 0.3 mg/kg of polymer, found DHBP at 1.7 to 15.5 mg/kg, and found migration into a milk simulant within the limits and thresholds its authors applied. Our research also records a 2025 Food Control study reporting particle release from tested PPSU feeding bottles that rose with temperature; we could not re-read that abstract.

How concerned to be

The 2018 result is reassuring inside its conditions but is not proof that every current PPSU bottle is the same, and, as our research records it, the 2025 products came from Chinese e-commerce channels and cannot be assigned to a named US bottle. We treat PPSU as a reasonable lightweight, high-heat option that is still a polymer: not inert, not particle-free, and not a reason to skip checking the rest of the fluid path.

What it's called on a label

Look for any of these on an ingredient list: Polyphenylsulfone, PPSF, Radel, PPSU.

Sources

  1. Polyphenylsulfone (PPSU) for baby bottles: a comprehensive assessment on polymer-related non-intentionally added substances (NIAS), Food Additives & Contaminants: Part A (PubMed) (2018)
  2. Microplastics release from infant feeding bottles and milk storage bags, Food Control (2025)