Wearing face masks is an important and widely applied public health measure to control the COVID-19 pandemic1. A recent study, testing several batches of face masks intended to be put on sale as personal protective equipment, showed that 70% of the examined face masks contained TiO2 in quantities ranging from 100 to 2000 mg kg−12. This suggests that TiO2 is commonly applied in textiles of face masks, as in a wide variety of other textiles, e.g. to improve stability to ultraviolet light, as white colorant or as a matting agent3,4. In addition, to introduce new solutions to the challenges associated with the COVID-19 pandemic, textile companies are incorporating specific nanofiber, nanocomposite and nanoparticle technology into face masks5,6. Nanofibers containing TiO2 nanoparticles have been produced to create antimicrobial filters7, also in combination with silver8 and graphene9. Coatings of TiO2 nanoparticles on cotton fabric were applied for enhanced self-cleaning and antibacterial properties10.

In their recent opinion paper, Palmeiri et al.5 warn for the possible future consequences caused by a poorly regulated use of nanotechnology in textiles applied to improve the performance of face masks. In animal experiments, toxic effects were reported when TiO2 particles were inhaled11,12, as well as when they were ingested orally13,14. In 2017, the Risk Assessment Committee (RAC) of the European Chemical Agency (ECHA) reviewed the carcinogenic potential of TiO2 and proposed to classify Titanium dioxide as Carc. 2, H351 (suspected human carcinogen)15 by inhalation. This CLP classification16 was adopted for titanium dioxide.

To evaluate whether the TiO2 particles in face masks possibly present a health risk, their amounts, their physicochemical properties and their localization were analyzed in a selection of face masks. Supporting on these measurements, the amount of TiO2 at the surface of the textile fibers was estimated and compared with the acceptable exposure level to TiO2 by inhalation, expressed per mask (AELmask).

Results and discussion

Twelve face masks meant to be worn by the general population and including both single-use (disposable) and re-usable masks were obtained from various suppliers in Belgium and the EU. The origin of the masks is worldwide. The selected masks consist of a variety of fibers, including synthetic fibers, such as polyester, polyamide and meltblown and thermobonded non-woven fabrics; and natural fibers, such as cotton (Table 1). All masks are NIOSH uncertified, Mask04 and Mask07 have a CE logo; Mask03 and Mask07 are OEKO-TEX certified. Mask01, 04 and 05 are three ply type masks17,18. Images of the examined masks are given as Supplementary Information 1.

read more: https://www.nature.com/articles/s41598-022-06605-w#Sec3