Titanium dioxide (TiO2) is generally applied in commercial textile products. This study investigated in situ whether TiO2 (nano)particles are present in a selection of face masks available for the general population. In addition, a preliminary risk analysis was performed, focusing on potential health risks associated with TiO2 particles in selected face masks, assuming an “intensive use” scenario (in line with the advices of the Belgian government for the use of face masks against Covid-19 contamination) and subchronic exposure (multiple or continuous exposures occurring for a limited part of a person’s lifetime) of the general adult population.
Presence of titanium dioxide in face masks
In situ analysis demonstrated the presence of agglomerated TiO2 (nano)particles in all examined face masks that contain polyester or polyamide (nylon) fibres, or that are made of non-woven, synthetic fabrics. These particles resemble fibre-grade TiO2 particles that are used in the production of the fibers. The amounts of TiO2 in face masks varied from a few micrograms to 0.15 grams per mask. The observed TiO2 particles are located both on the surface and in the core of the textile fibres. Current scientific evidence shows that the migration potential of particles from the core of the fibre is extremely rare. The particles at the external surface of the fibres may, however, potentially be released and subsequently inhaled. Based on these data, an initial risk assessment was performed.
Assessing potential health risks
Because there are no methods available for measuring exposure directly, we applied the methodology of the Agence nationale de sécurité sanitaire de l’alimentation, de l’environnement et du travail (ANSES) to determine the exposure limits to nanosized TiO2 particles. An Acceptable Exposure Level (AEL) per mask of 3.6 µg was calculated using a scenario assuming intensive use of face masks. For each mask we compared the AEL per mask with the amount of TiO2 at the fibre surface. Our calculations show that for most of the examined masks the AEL is exceeded and a potential health risk cannot be excluded when they are intensively used. However, it has to be noted that this is a theoretical risk, and not a proven one based on real exposure data.
Many uncertainties with regard to the degree of exposure remain and in our assessment. We have taken a prudent (conservative) toxicological approach. So far, research on TiO2 particles in textiles and particularly on their release, is extremely limited, but currently, we have no indications that TiO2 particles are actually released in large amounts.
In some face masks, however, the amount of titanium dioxide is so high that a health risk cannot be excluded, even if we consider that only a small fraction of the TiO2 particles at the surface is released and inhaled. In addition, EFSA has concluded that TiO2 can no longer be considered as a safe food additive because potential damage to the consumer’s genetic material (genotoxicity) cannot be ruled out. We therefore advise to issue precautionary standards to limit the presence of TiO2 particles in face masks. In the context of preventing the spread of COVID-19 we support the recommendations issued by the authorities about the use of face masks.
Ongoing and future research
In the next phase of the project we will advance in the development of methodologies to assess the inhalation of TiO2 particles by mimicking real life conditions or by developing alternative techniques to measure the release of TiO2 particles from face masks. We will also further characterise TiO2 particles to better understand the hazard related to the particles, since their toxicity depends on their physicochemical properties.
In the course of the current project, we have identified several major challenges related to the analysis, characterisation and risk assessment of TiO2, and which go beyond the scope of the ongoing research project:
- In general, scientific data on the presence of nanoparticles in face masks, their characteristics, the exposure and the risks for the population is limited.
- Methodologies for characterising TiO2 particles in face masks are time consuming and expensive. Consequently, within the current project only a subsample of the face masks on the market was analysed. A systematic market study should be undertaken. Furthermore efforts are needed to build capacity for the characterisation and analysis of TiO2 particles in consumer goods and medical devices.
- The current Sciensano study on masks for the general population should be extended to assess the potential health risks associated with the presence of TiO2 particles in face masks worn by medical staff.
- Key information about the toxicity of TiO2 particles is missing for risk assessment: data about the hazard (inhalation toxicity threshold) of the specific TiO2 particles present in face masks should be determined in a robust, repeated dose inhalation study with fibre-grade TiO2 particles Furthermore, more toxicity and medical research is needed to assess the risk of vulnerable populations, especially children.
- Reference methods, reference materials including the appointment of a reference laboratory for the analysis and characterisation of nanoparticles are urgently needed for quality control and enforcement of legislation.
- Sharing the newly developed methodologies can further identify the problem at Belgian level, but the presence of TiO2 in face masks is a global problem. A solution will therefore at least require a common European approach.