The presence of iron oxide nanoparticles in the food pigment E172

Linn Voss, I-Lun Hsiao, Maximilian Ebisch, Janja Vidmar, Nadine Dreiack, Linda Böhmert, Valerie Stock, Albert Braeuning, Katrin Löschner*, Peter Laux, Andreas F. Thünemann, Alfonso Lampen, Holger Sieg

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


Iron oxides used as food colorants are listed in the European Union with the number E172. However, there are no specifications concerning the fraction of nanoparticles in these pigments.

Here, seven E172 products were thoroughly characterized. Samples of all colors were analyzed with a broad spectrum of methods to assess their physico-chemical properties. Small-Angle X-ray Scattering (SAXS), Dynamic Light Scattering (DLS), Transmission Electron Microscopy (TEM), zeta-potential, Inductively Coupled Plasma-Mass Spectrometry (ICP-MS), X-ray diffraction (XRD), Brunauer-Emmett-Teller analysis (BET), Asymmetric Flow Field-Flow Fractionation (AF4) and in vitro cell viability measurements were used.

Nanoparticles were detected in all E172 samples by TEM or SAXS measurements. Quantitative results from both methods were comparable. Five pigments were evaluated by TEM, of which four had a size median below 100 nm, while SAXS showed a size median below 100 nm for six evaluated pigments. Therefore, consumers may be exposed to iron oxide nanoparticles through the consumption of food pigments.
Original languageEnglish
Article number127000
JournalFood Chemistry
Number of pages9
Publication statusPublished - 2020


  • Iron oxide
  • Nanoparticles
  • E172
  • Food pigment


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