Two recent studies have proposed new methods to detect the presence of nanoparticles in food and cosmetics. The first study suggests a two-step approach to detect the banned food additive E 171. This involves screening for elemental titanium, followed by detecting nano-sized titanium dioxide. The second study used a quick screening tool to identify the presence of seven different nanoparticles in facial cosmetics. However, both methods have only been partially validated, and further improvements are required. There is a lack of reliable data on background titanium concentrations in food. A lack of reference matrices with known amounts of nanoparticles in consumer products is another challenge that needs to be addressed.

A two-step approach to detect banned food additive E 171 in food

Food additive E 171 (titanium dioxide, with a significant proportion of nano-sized particles) has been banned in the EU European Union (European Union). To ensure compliance with this ban, detecting whether E 171 is present in food is necessary. A new study proposes a two-step approach to do so. The first step involves screening for the presence of elemental titanium (Ti), using inductively coupled plasma mass spectrometry (ICP-MS). If elemental titanium is detected, the next step is to detect nano-sized titanium dioxide using single particle (SP) ICP-MS. This method enables characterizing the number-based particle size distribution. The second step has undergone interlaboratory comparison already in 2021. The new study reports on the development of the first step. This step is challenging because it requires detecting low concentrations of Ti. And there is a lack of reliable data on background Ti concentrations in food. The dataset of naturally occurring Ti concentrations in food should be improved. This should include the existence (if any) of potential Ti-rich food. Until such a dataset is available, control laboratories may compare suspect samples with those of equivalent products. 

Detection of seven different nanoparticles in facial cosmetics  

In the EU cosmetics with nanoparticles are required to be labeled. To ensure compliance with this labelling, it is important to know if cosmetics contain them. To address this, researchers used a quick screening tool to check for the presence of nanoparticles in powder-based facial cosmetics. They found nanoparticles in seven different facial cosmetic products using SP-ICP-MS. Based on the elemental metal composition, they were able to semi-quantitatively measure seven different nanoparticles (Mn, Zn, Cr, Pb, Bi, Sn, and Mg). The amount of aluminum was too high to quantify, and that of silver was too low. The number of different nanoparticles per product was between one and five. 

The authors state that the method’s biggest challenge is the lack of commercially available reference materials in matrices like those found in consumer products. Dilution could help minimize matrix effects. 

Reflections by RIVM 

The two studies have reported new methods to detect the presence of specific nanoparticles in food and cosmetics. However, these methods have only been partially validated. It is unclear whether they work for all types of food and cosmetics, and for all nanoparticles. For example, some common nanoparticles added to cosmetics include SiO2 and TiO2. These were not included in the study on cosmetics. To address these issues, the EFSA should discuss creating a register of titanium background quantities in food. Similarly, SCCS should discuss developing reference materials with a known quantity of nanoparticles in consumer products. With these measurement approaches, it seems technically possible to enforce the presence and absence of nanoparticles, although it remains a challenging task. The challenge may be even larger for nanoparticles without metallic components.