Repository logo

Browsing by Issue Date, starting with "2022-09-27"

Filter results by year or month
Now showing 1 - 2 of 2
  • Occupational exposure to emerging cellulose nanomaterials and potential respiratory effects: uncovering exposure-effect relationships using in vitro systems
    Publication . Ventura, Célia; Pinto, Fátima; Vieira, Luís; Louro, Henriqueta; Silva, Maria João
    The application of innovative cellulose nanomaterials (CNMs), particularly, cellulose micro- and nanofibrils (CMF, CNF) and nanocrystals (CNC), in technology and biomedicine has expanded in recent years. However, there is still a lack of reliable indicators to assess workers’ exposure, mainly by inhalation, and the associated health outcomes. This study aimed at identifying genotoxic, oxidative stress, or epigenetic endpoints that could be used as promising effect biomarkers to predict health outcomes from CNMs exposure, exploitable for human biomonitoring. Three well-characterized CNMs were used, at a low concentration range, to expose cell systems representative of the respiratory tract, namely, bronchial epithelial (BEAS-2B) cells or co-cultures of lung (A549) and macrophage-like (THP-1) cells. No induction of chromosomal instability was detected in co-cultures for all types of CNMs analysed through the cytokinesis-block micronucleus assay. Likewise, neither significant toxic effects nor oxidative stress was found. Interestingly, preliminary data showed differentially expressed microRNAs in BEAS-2B cells after exposure to CNC, but not to CMF or CNF, compared to untreated cells. Moreover, a profile of microRNAs associated with CNC exposure was identified. Overall, no major concern regarding CNMs genotoxicity and oxidative stress was raised. Epigenetic effects were uncovered for CNC and the identified miRNA profile has potential to be used as an effect biomarker for occupational biomonitoring. However, further investigation with longer exposures and validation of that profile using in vivo models must be conducted, to prove its value to assess early effects from CNMs exposure.
    2022-09-27Conference object Restricted access Show more
  • Toxicological Assessment of Cellulose Nanomaterials: Oral Exposure
    Publication . Vital, Nádia; Ventura, Célia; Kranendonk, Michel; Silva, Maria João; Louro, Henriqueta
    Cellulose nanomaterials (CNMs) have emerged recently as an important group of sustainable bio-based nanomaterials (NMs) with potential applications in multiple sectors, including the food, food packaging, and biomedical fields. The widening of these applications leads to increased human oral exposure to these NMs and, potentially, to adverse health outcomes. Presently, the potential hazards regarding oral exposure to CNMs are insufficiently characterised. There is a need to understand and manage the potential adverse effects that might result from the ingestion of CNMs before products using CNMs reach commercialisation. This work reviews the potential applications of CNMs in the food and biomedical sectors along with the existing toxicological in vitro and in vivo studies, while also identifying current knowledge gaps. Relevant considerations when performing toxicological studies following oral exposure to CNMs are highlighted. An increasing number of studies have been published in the last years, overall showing that ingested CNMs are not toxic to the gastrointestinal tract (GIT), suggestive of the biocompatibility of the majority of the tested CNMs. However, in vitro and in vivo genotoxicity studies, as well as long-term carcinogenic or reproductive toxicity studies, are not yet available. These studies are needed to support a wider use of CNMs in applications that can lead to human oral ingestion, thereby promoting a safe and sustainable-by-design approach. View Full-Text
    2022-09-27Journal article Open access Show more