Iron oxides and hydroxides (E172)

Iron oxides and hydroxides are the colors the food industry lists as E172. In our table they are moderate risk: they take 15 points off the additive subscore, a third of a product's score (about 5 of the 100).

What Iron oxides and hydroxides do to a score

A packaged food's additive subscore starts at 100 and loses points for each additive on the label; that subscore is a third of the final score. Iron oxides and hydroxides take 15 points off the additive subscore, a third of a product's score (about 5 of the 100). Scan the pack in Sito and the score you get is the one for your own child's age, with this additive named in the reasons. How we score has the whole method.

What the sources found

Every classification in our table comes from the citations below, and nothing else. Each finding is our one-line summary of what the source concluded, with the source and reference beside it.

• EFSA 10.2903/j.efsa.2015.4317 (EFSA Journal 2015;13(12):4317 — Scientific Opinion on the re-evaluation of iron oxides and hydroxides (E 172) as food additives)
  'Red and black iron oxide, both in nano- and micro-form, were positive in in vitro genotoxicity assays in mammalian cells. Due to the limitations of the database, and considering the impossibility to read-across between iron oxides with different redox state, the Panel considered that the genotoxicity of iron oxides cannot be evaluated based on the available data.' 'The Panel concluded that an adequate assessment of the safety of E 172 could not be carried out because a sufficient biological and toxicological database was not available.'
• EFSA European Commission, 'Call for scientific and technical data on the permitted food additives iron oxides and hydroxides (E 172)', published 5 December 2016 (food.ec.europa.eu, fs_food-improvement-agents_reeval_call_20161205_e172_data.pdf)
  Official EU restatement of the EFSA conclusions verbatim. Records that 'In 1980, an acceptable daily intake (ADI) of 0-0.5 mg/kg bw/day was established by the Joint FAO/WHO Expert Committee on Food Additives (JECFA)', that the Panel recommended particle size and particle size distribution be included in the specifications 'because of the potential importance of nanoparticles in toxicokinetics and toxicological effects', and that refined exposure ranged 'from 0.03 mg/kg bw/day for infants to 3.7 mg/kg bw/day for toddlers at the mean and from 0.1 mg/kg bw/day for infants to 9.5 mg/kg bw/day for toddlers at the 95th percentile for the non-brand-loyal scenario'.
• FDA 21 CFR 73.200 (Synthetic iron oxide) — Part 73 "Listing of Color Additives Exempt from Certification", Subpart A "Foods"; verified against the current eCFR structure
  Synthetic iron oxide is a US colour additive exempt from certification listed for human food use, so E 172 appears in products commonly sold in the US; the section carries its own identity and specification requirements for the human-food grade.
• EU law Regulation (EC) No 1333/2008 Annex II, consolidated text 02008R1333 — EN — 16.12.2024 — 059.001 (EUR-Lex ELI: reg/2008/1333)
  E 172 iron oxides and hydroxides authorised in the EU, including at quantum satis in some categories and as a contrast enhancer for marking citrus fruit and melons; authorisation continues while the data gaps identified in 2015 are addressed.

Why this class

IARC Group 2B; or an EFSA re-evaluation that flagged genotoxicity data gaps, found safety could not be assessed on the available data, or cut the ADI citing child exposure; or an EU harmonised classification of the substance as a reproductive or developmental hazard; or an EU withdrawal of one authorised food use while others remain; or an OEHHA/Proposition 65 listing; or membership of the Southampton-six colourants.

Our confidence in this row's classification is high. Medium or low does not mean the evidence is weak; it means something about the row is still being pinned down, usually a regulatory status confirmed from one source rather than two.

Questions parents ask

Are Iron oxides and hydroxides (E172) safe for kids?

Moderate risk. In Sito it takes 15 points off the additive subscore, a third of a product's score (about 5 of the 100). The finding we rely on: 'Red and black iron oxide, both in nano- and micro-form, were positive in in vitro genotoxicity assays in mammalian cells. Due to the limitations of the database, and considering the impossibility to read-across between iron oxides with different redox state, the Panel considered that the genotoxicity of iron oxides cannot be evaluated based on the available data.' 'The Panel concluded that an adequate assessment of the safety of E 172 could not be carried out because a sufficient biological and toxicological database was not available.' (EFSA, 10.2903/j.efsa.2015.4317 (EFSA Journal 2015;13(12):4317, Scientific Opinion on the re-evaluation of iron oxides and hydroxides (E 172) as food additives)).

What is E172?

E172 is the E number for Iron oxides and hydroxides, which our table lists as a color. Open Food Facts tags it en:e172.

Next to it on the label

The E numbers either side of E172 in our table, then the closest colors by number.

• Lutein (E161b), low risk, flagged for young children
• Beetroot red (E162), no risk identified
• Anthocyanins (E163), no risk identified
• Calcium carbonates (E170), no risk identified
• Titanium dioxide (E171), high risk
• Aluminium (E173), moderate risk, flagged for young children