Iron oxides and hydroxides, collectively known as E172 in Europe, are a group of colorants derived from iron. These pigments are known for their strong color intensity and stability, making them a popular choice for manufacturers across many industries. However, the journey to a full safety assessment has been complex, revealing more questions than answers in recent years.
What is E172?
E172 refers to a class of synthetic iron-based pigments that provide a range of colors from yellow to red, brown, and black. They are synthesized from iron sulfate or iron chloride compounds and are chemically identical to their naturally occurring mineral forms. The different color variations are identified by specific C.I. numbers:
- E172(i): Black iron oxide (C.I. Pigment Black 11)
- E172(ii): Red iron oxide (C.I. Pigment Red 101)
- E172(iii): Yellow iron oxide (C.I. Pigment Yellow 42)
Where is E172 used?
E172 is not limited to food but is a versatile coloring agent found in numerous products:
- Food: Used in confectionery, processed meat products, dessert mixes, spreads, and the coloring of olive surfaces.
- Cosmetics: A staple in makeup, including eyeshadows, lipsticks, and foundations, due to its non-toxic nature and stable color.
- Pharmaceuticals: Used to color the coatings of tablets and capsules for identification purposes.
- Industry: Found in paints, coatings, ceramics, and construction materials.
Regulatory Status: A Complex Picture
Regulatory bodies worldwide have long considered E172 safe. In the United States, the FDA lists iron oxides as "Generally Recognized As Safe" (GRAS). The traditional understanding held that these iron oxides were not significantly absorbed by the body when ingested and were primarily excreted.
However, a 2015 re-evaluation by the European Food Safety Authority (EFSA) revealed significant gaps in the toxicological data available for E172. The EFSA Panel concluded that a full safety assessment could not be performed with the information provided by the industry at the time. This triggered a new call for data from manufacturers in EU member states.
The Nanoparticle Question
One of the most critical aspects of the recent E172 discussion revolves around nanoparticles. While the iron oxides in E172 were previously thought to be micro-sized and non-absorbable, recent studies have detected nanoscale components within the food-grade versions. Nanoparticles behave differently in the body compared to larger particles and can potentially cross biological barriers, leading to increased absorption and accumulation in tissues and organs. The long-term health implications of this are currently not well understood.
Concerns and Potential Health Implications
Beyond the nanoparticle issue, several other potential concerns have been raised regarding E172:
- Genotoxicity: In vitro tests cited by EFSA indicated positive genotoxicity assays in mammalian cells for both nano- and micro-forms of red and black iron oxides. This indicates a potential to damage genetic material, although the relevance for human health requires further investigation.
- Heavy Metal Impurities: The 2015 EFSA assessment also noted that specifications for certain heavy metal impurities like cadmium, arsenic, lead, and mercury needed revision to ensure E172 is not a significant source of exposure to these toxic elements.
- Aluminum Contamination: Some sources have raised concerns that certain E172 dyes may contain aluminum without being explicitly labeled, a metal linked to neurological issues.
- Excessive Iron Intake: While distinct from E172's coloring role, consuming excessive iron in any form can lead to iron overload (hemochromatosis) and liver damage. This is particularly relevant for those with pre-existing iron metabolism disorders.
E172 Safety Profile: Old vs. New Understanding
| Feature | Traditional View (Largely before 2015) | Modern Understanding (Post-2015 EFSA) |
|---|---|---|
| Absorption | Considered non-absorbable by the intestinal tract. | Nanoparticle component can lead to absorption and potential tissue deposition. |
| Data Status | Considered sufficiently safe based on available data and inertness. | Identified with significant data gaps concerning genotoxicity and long-term effects. |
| Health Risks | Very low risk, primarily for industrial inhalation. | Potential genotoxicity concerns raised by in vitro studies. |
| Contaminants | Impurity limits were considered adequate. | Need for stricter limits on heavy metal impurities recognized. |
Conclusion: Navigating Uncertainty
So, is E172 safe? The answer is not as straightforward as it once seemed. While regulatory bodies like the FDA still affirm its safety, the detailed scientific assessment by EFSA in 2015 identified crucial data deficiencies and a possible genotoxicity risk that has not been fully resolved. The discovery that E172 can contain nanoparticles and may be absorbed by the body further complicates the picture, as the long-term effects of this are largely unknown. Consumers should be aware that approval status does not always equate to a guarantee of absolute safety, especially when new scientific insights emerge. The ongoing demand for more data reflects a crucial need for further research to provide a definitive answer on the safety of E172.
For more information on the EFSA's re-evaluation of E172, you can read the report here: Re-evaluation of iron oxides and hydroxides (E 172) as food additive.
