Although titanium dioxide (TiO2) is a suspected human carcinogen when inhaled, fiber-grade TiO2 (nano)particles were demonstrated in synthetic textile fibers of face masks intended for the general public. STEM-EDX analysis on sections of a variety of single use and reusable face masks visualized agglomerated near-spherical TiO2 particles in non-woven fabrics, polyester, polyamide and bi-component fibers. Median sizes of constituent particles ranged from 89 to 184 nm, implying an important fraction of nano-sized particles (< 100 nm). The total TiO2 mass determined by ICP-OES ranged from 791 to 152,345 µg per mask. The estimated TiO2 mass at the fiber surface ranged from 17 to 4394 µg, and systematically exceeded the acceptable exposure level to TiO2 by inhalation (3.6 µg), determined based on a scenario where face masks are worn intensively. No assumptions were made about the likelihood of the release of TiO2 particles itself, since direct measurement of release and inhalation uptake when face masks are worn could not be assessed. The importance of wearing face masks against COVID-19 is unquestionable. Even so, these results urge for in depth research of (nano)technology applications in textiles to avoid possible future consequences caused by a poorly regulated use and to implement regulatory standards phasing out or limiting the amount of TiO2 particles, following the safe-by-design principle.

The joint Nanofood@ -EFSAnano project developed analytical methodologies for identification and characterization of nanoparticles in food additives. The methodologies were applied in a regulatory context for control and risk identification purposes. In specific, the project developed methods to characterize E 171 (titanium dioxide), E 174 (silver) and E 175 (gold) food additives in their pristine state and in the food matrix. The project focused on method development based on TEM and (sp)ICP-MS, method standardization and validation, and application of the methods in a wider scope for market surveillance. In addition, a pristine E 171 intra-laboratory reference material was produced; 300 homogeneous and stable vials were fractionated and a homogeneity study was performed. The methodologies, analysis results and the developed expertise form a strong base to fulfil control activities and to provide expertise in the characterization of materials which may contain a fraction of nanoparticles, applied in the food chain. They can be applied to implement the "EFSA guidance on technical requirements for regulated food and feed product applications to establish the presence of small particles including nanoparticles", and the "EFSA guidance on the human and animal risk assessment of the application of nanoscience and nanotechnologies in agri/food/feed".

Gammaherpesviruses are important human and animal pathogens. Infection control has proven difficult because the key process of transmission is ill understood. Murid herpesvirus 4 (MuHV-4), a gammaherpesvirus of mice, is transmitted sexually. We show that this depends on the major virion envelope glycoprotein gp150. gp150 is redundant for host entry, and in vitro, it regulates rather than promotes cell binding. We show that gp150-deficient MuHV-4 reaches and replicates normally in the female genital tract after nasal infection but is poorly released from vaginal epithelial cells and fails to pass from the female to the male genital tract during sexual contact. Thus, we show that the regulation of virion binding is a key component of spontaneous gammaherpesvirus transmission.IMPORTANCE Gammaherpesviruses are responsible for many important diseases in both animals and humans. Some important aspects of their life cycle are still poorly understood. Key among these is viral transmission. Here we show that the major envelope glycoprotein of murid herpesvirus 4 functions not in entry or dissemination but in virion release to allow sexual transmission to new hosts. KEYWORDS gammaherpesvirus, glycoprotein, release, transmission T ransmission is the main motor of viral evolution, and the large disease burden imposed by human gammaherpesviruses reflects very high infection prevalences due to efficient transmission from carriers to new hosts (1). Epstein-Barr virus (EBV) and Kaposi's sarcoma-associated herpesvirus (KSHV) infect up to 90% (2) and 30% (3) of humans worldwide, respectively. Endemic infections are maintained chiefly by carriers shedding virus in their saliva. However, in populations with a low prevalence of infection, sexual transmission becomes important due to increased contact (4). This was seen clearly for KSHV transmission associated with HIV infection (5) and may also apply to EBV (6).While interrupting transmission is the sine qua non of infection control, analyzing EBV and KSHV transmission has proven difficult. Natural EBV infection is asymptomatic for at least a month (6), and experimental transmission is made difficult by many EBV and KSHV functions being host specific. However, gammaherpesviruses colonize most mammals, so related animal viruses, such as murid gammaherpesvirus 4 (MuHV-4), provide another way to understand infection in vivo (7). Luciferase (Luc) imaging of MuHV-4 infection (8) revealed genital infection following intranasal (i.n.) inoculation of female mice, which then spread to naive males by sexual contact (9). This has provided

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