E172 – Iron oxides and hydroxides - Food additives database

Safety grading ORANGE – SOME CONCERNS

E172, known as iron oxides and hydroxides, is generally considered safe for use as a food colouring additive. Regulatory authorities including the European Food Safety Authority (EFSA) and the U.S. Food and Drug Administration (FDA) allow its use in many categories of food. However, it carries an ORANGE rating due to certain controversies. The concerns revolve around purity, possible contamination with heavy metals (like lead or arsenic), and the limited data on nano-sized particles of iron oxides used in foods. Some studies have suggested potential oxidative stress and accumulation risks if consumed in very high amounts, but evidence in humans remains limited.

Iron oxides have been used for decades in confectionery, baked goods, and pharmaceuticals. The additive is poorly absorbed in the digestive tract, which reduces toxicity risks. Nonetheless, safety agencies recommend limiting impurities and ensuring only food-grade pigments are used. For this reason, we classify E172 as ORANGE – SOME CONCERNS.

Should you avoid E172?

For most consumers, occasional consumption of foods containing E172 is not a significant health risk. However, people who regularly eat products with synthetic colourings, or those who are sensitive to additives, may choose to avoid it when possible. Children and individuals with iron metabolism disorders might be advised to minimize exposure. Choosing foods with natural colourings like beetroot extract or turmeric is a safer alternative for those looking to reduce synthetic additives.

Although typical food-grade pigments are mostly non-nano, some products may inadvertently contain nanoparticles, which pose greater risk. Also purity and contamination (heavy metals like lead, arsenic) are concerns, and some regulatory reviews call for stricter impurity limits.

Common Uses

Chocolate and confectionery coatings
Cake decorations and icings
Pharmaceutical capsules and tablets
Processed cheese
Decorative surface colouring in candies and pastries

Common names / Synonyms

CI Pigment Yellow 42
CI Pigment Red 101
CI Pigment Black 11
Ferric oxide
Iron(III) oxide-hydroxide

What is it?

E172 is a group of colour additives consisting of iron oxides and hydroxides. These compounds are inorganic pigments that provide shades of red, yellow, brown, and black. They occur naturally in minerals like hematite and goethite, but food-grade E172 is usually produced synthetically to meet purity standards.

Production involves controlled precipitation, calcination, or dehydration of iron salts to obtain the required pigment form. For instance, yellow iron oxide (hydrated iron oxide) is produced by precipitating iron(III) salts with an alkali, while red iron oxide is often obtained by calcination at high temperatures. Black iron oxide is prepared by partial oxidation of ferrous compounds.

These pigments are insoluble in water and resistant to light, heat, and acids, which makes them ideal for stable colouring in food and pharmaceutical applications. Although not bioavailable as dietary iron, they have long been valued for safety and stability compared to some organic dyes.

Where it’s allowed (EU vs US)

In the European Union, E172 is permitted for use in specific food categories under strict purity specifications.

In the United States, iron oxides are allowed as color additives for certain applications, especially in pharmaceuticals and cosmetics, and in limited food uses.

Globally, most countries follow EU or FDA guidance, although some markets restrict their use in baby food.

E172 – Iron oxides and hydroxides