Personal Protective Equipment (PPE) has become part of our lives in recent times, playing a very important role in the fight of COVID-19, namely for health professionals who are at increased risk. PPE distribution networks are very important, either to face this wave of COVID-19 as well as to face hypothetical others. We also get the information that this type of equipment does not yet exist in sufficient quantity on the market to supply the needs worldwide, and that, in some cases, it can reach very high prices. On the other hand, we know that they are mostly made of plastic, which ends up in our oceans, thus increasing their pollution. The project “Gamma sterilization and reuse of PPE”, led by professor Ana Paula Serro (CQE), provides a safe and ecological solution. It will evaluate the possibility of using gamma radiation to sterilise PPE, such as face masks, clothing, etc.

“To assess this possibility, several materials will be identified – already used in the production of PPE or with potential for future use – subject to sterilization by this method. The ideal sterilization and the number of times for each PPE to be reprocessed will be defined in order to comply with the rules that ensure the safety and effectiveness of PPEs”, explains professor Ana Paula Serro. “In some cases, additional sterilization treatments may be necessary to restore materials functions, which will also be subject to study in this project”, adds the CQE researcher.

In order to evaluate the possibility of using gamma radiation to sterilise PPE, the team will use a 60Co source in the Technological Unit for Radiosterilization, located at Técnico – CTN Campus, which is “a unique infrastructure in the country”, says the project leader. “This sterilization method is recognised by the International Atomic Energy Agency (IAEA) as an effective tool for the elimination of SARS-CoV-2 in different types of PPE and has many advantages over other methods currently available”, underlines professor Ana Paula Serro.

This method allows the used PPE to be sterilised in sealed packages, thus reducing the transmission risk associated with the handling process. In addition, it also avoids toxic waste, which besides being ecological, allows the immediate reuse of PPE. “The process is carried out at room temperature and takes a few hours. The sterilization time wil depend on the applied radiation dose”, explains the Técnico professor. Another advantage of this method is that it allows the simultaneous processing of large quantities of material, which contributes to reduce costs.

Although most PPE is disposable, professor Ana Paula Serro clarifies that “many PPEs can be effectively and safely reused, provided that they are sterilised and maintain adequate performance”. According to the Técnico professor, “the reuse of PPE is valuable input for healthcare units, with a positive impact both on the economy and environment”.

The project was selected by FCT – 2nd edition of the “RESEARCH 4 COVID-19”, and got a €39,808 funding. The project will start in July and, according to professor Ana Paula Serro, “the team has extensive experience with a broad range of medical devices, and has been developing joint work for several years”.

The CQE and IPFN researchers will be responsible for the irradiation of materials, their characterisation and possible post sterilization modifications. The project brings together researchers from the Applied Microbiology Laboratory Egas Moniz (LMAEM) who will carry out sterilization testing. “CITEVE, the Portuguese Technological Centre for the Textile and Clothing Industry, will be responsible for choosing the materials for the study and enforcement of applicable regulations”, says the project leader. Clínica Dentária Universitária Egas Moniz and Centro Hospitalar Universitário de Lisboa Central (Hospital de São José) will help identify the most relevant PPEs and carry out validation after sterilization. “In total, 10 researchers will be involved: 8 seniors and 2 juniors – to be hired”, shares professor Ana Paula Serro.

Once developed, the sterilization model can be used by healthcare units. “Despite the several advantages of sterilization with gamma radiation, it can only be performed by experts in units specifically prepared for this purpose”, highlights the project leader.