Surgical face masks are more present than ever as personal protective equipment due to the COVID-19 pandemic. In
this work, we show that the contents of regular surgical masks: i) polypropylene microfibres and ii) some added metals
such as: Al, Fe, Cu, Mn, Zn and Ba, may be toxic to some marine life. This work has got two objectives: i) to study the
release rate of the products from face masks in marine water and ii) to assess the toxicity in Phaeodactylum tricornutum
of these by-products. To achieve these two objectives, we performed release kinetic experiments by adding masks in
different stages of fragmentation to marine water (i.e. whole face masks and fragments of them 1.52 ± 0.86 mm). Released microfibres were found after one month in shaking marine water; 0.33 ± 0.24 and 21.13 ± 13.19 fibres·mL−1
were collected from the whole and fragmented face masks, respectively. Significant amounts of dissolved metals such
as Mn, Zn and Ni, as well as functional groups only in the water containing the face mask fragments were detected.
Water from both treatments was employed to study its toxicity on the marine diatom. Only the water from the face
mask fragments showed a significant, dose-dependent, decrease in cell density in P. tricornutum; 53.09 % lower than
in the controls. Although the water from the face mask fragments showed greater effects on the microalgae population
than the water from the whole face mask, the latter treatment did show significant changes in the photosynthetic apparatus and intrinsic properties of the cells. These results indicate that during fragmentation and degradation face
masks a significant chemical print can be observed in the marine environment.
