Laboratory for Integrative and Translational Research in Population Health

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Assessing the in vitro toxicity of engineered and airborne nanoceramics: contribution to the safe production and use of nanomaterials in the ceramic industry

Publication . Bessa, Maria João; Fraga, Sónia; Teixeira, João Paulo; Laffon, Blanca Lage

Advanced ceramic technologies have a strong potential for airborne (nano)particle formation and emission, meaning that workers of those industries are at great risk of exposure to these particles. However, toxicological data of these (nano)particles is lacking, particularly for airborne particles released within sectors such as the ceramic industry. To address this relevant topic, the present work aimed to assess the toxicity of occupationally relevant doses of industrially process-generated particles emitted during two industrial thermal spraying technologies [atmospheric plasma spraying (APS) and high velocity oxy-fuel (HVOF)], as well as of four engineered nanoparticles [ENP; tin oxide (SnO2), antimony-tin oxide (ATO; Sb2O3●SnO2), cerium oxide (CeO2) and zirconium oxide (ZrO2)] used as raw materials for ceramics manufacture. Two human respiratory in vitro systems, either conventional alveolar epithelial A549 cultures under submerged or air-liquid interface (ALI) conditions, or advanced three-dimensional (3D) upper airway epithelium (MucilAirTM) cultures at ALI were exposed to the selected particles. Major toxicity endpoints including plasma membrane integrity, metabolic activity, oxidative stress, inflammatory response, and genotoxicity were assessed. Overall, the tested process-generated particles seem to be more toxic compared to the ENP, most likely due to their higher chemical complexity and composition [elevated levels of metallic elements like chromium (Cr) and nickel (Ni)]. Among the two evaluated thermal spraying processes, particles derived from HVOF were more cytotoxic than those emitted from APS. Either fine (PGFP) and ultrafine (PGNP) particles from both spraying processes were able to induce measurable genotoxic effects. While APS particles lead to increased levels of histone 2AX (H2AX) phosphorylation, HVOF particles caused 8-oxo-7,8-dihydroguanine (8-oxo-G) oxidative DNA lesions. ENP were more toxic to human alveolar epithelial cultures when aerosolised than in liquid suspension, particularly ZrO2 NP. On the other hand, advanced MucilAirTM cultures, that better mimic in vivo physiological features, such as the mucociliary defence mechanisms, were quite resistant to both HVOF-derived particles and ENP aerosols. Thus, while 3D human upper airway epithelial cultures exhibited attenuated responses, the conventional A549 cultures were more sensitive to the studied (nano)particles.The present work highlights the hazard of industrially derived (nano)particles, either intentionally used or incidentally released into the workplace air during advanced ceramic processes. Importantly, particles’ physicochemical properties alongside the testing conditions (cell model and type of exposure) played a determinant role in the observed biological responses. These findings reinforce the importance of using physiologically relevant in vitro models in (nano)particle toxicity studies, for better data extrapolation to humans.

2022-07-01Doctoral thesis

Open access

Multiparametric in vitro genotoxicity assessment of different variants of amorphous silica nanomaterials in rat alveolar epithelial cells

Publication . Brandão, Fátima; Costa, Carla; Bessa, Maria João; Valdiglesias, Vanessa; Hellack, Bryan; Haase, Andrea; Fraga, Sónia; Teixeira, João Paulo

The hazard posed to human health by inhaled amorphous silica nanomaterials (aSiO2 NM) remains uncertain. Herein, we assessed the cyto- and genotoxicity of aSiO2 NM variants covering different sizes (7, 15, and 40 nm) and surface modifications (unmodified, phosphonate-, amino- and trimethylsilyl-modified) on rat alveolar epithelial (RLE-6TN) cells. Cytotoxicity was evaluated at 24 h after exposure to the aSiO2 NM variants by the lactate dehydrogenase (LDH) release and WST-1 reduction assays, while genotoxicity was assessed using different endpoints: DNA damage (single- and double-strand breaks [SSB and DSB]) by the comet assay for all aSiO2 NM variants; cell cycle progression and γ-H2AX levels (DSB) by flow cytometry for those variants that presented higher cytotoxic and DNA damaging potential. The variants with higher surface area demonstrated a higher cytotoxic potential (SiO2_7, SiO2_15_Unmod, SiO2_15_Amino, and SiO2_15_Phospho). SiO2_40 was the only variant that induced significant DNA damage on RLE-6TN cells. On the other hand, all tested variants (SiO2_7, SiO2_15_Unmod, SiO2_15_Amino, and SiO2_40) significantly increased total γ-H2AX levels. At high concentrations (28 µg/cm2), a decrease in G0/G1 subpopulation was accompanied by a significant increase in S and G2/M sub-populations after exposure to all tested materials except for SiO2_40 which did not affect cell cycle progression. Based on the obtained data, the tested variants can be ranked for its genotoxic DNA damage potential as follows: SiO2_7 = SiO2_40 = SiO2_15_Unmod > SiO2_15_Amino. Our study supports the usefulness of multiparametric approaches to improve the understanding on NM mechanisms of action and hazard prediction.

2023-12-01Journal article

Open access

Portuguese wildland firefighters: assessing exposure and cytogenetic effects in non-fire settings during the pre-fire season

Publication . Pires, Joana; Esteves, Filipa; Slezakova, Klara; Madureira, Joana; Vaz, Josiana; Fernandes, Adília; Pereira, Maria do Carmo; Morais, Simone; Teixeira, João Paulo; Costa, Solange

IARC has recently listed occupational exposure as a firefighter carcinogenic to humans. However, firefighter is among the least studied occupations. The goal of the present study was to assess the level of cytogenetic damage in buccal mucosa (first-contact exposure tissue) of Portuguese firefighters during the pre- wildland fire season, as well as, to evaluate firefighters ́ exposure to particulate matter (PM) on fire stations as a baseline for occupational exposure characterization. A group of 172 Portuguese wildland firefighters were enrolled in the study, relevant information was obtained through a questionnaire. The frequency of micronucleus and other endpoints were evaluated via buccal micronucleus cytome assay (BMCyt) along with the influence of potential risk factors (e.g., smoking habits). Estimated inhalation doses of PM10 and PM2.5 (indoor/outdoor) were estimated for a group of 80 firefighters. No significant associations were found between estimated inhaled doses and BMCyt endpoints. Some lifestyle/behavioural variables were shown to significantly decrease the levels of cytogenetic endpoints, whereas others were found to increase them. Firefighters of the Permanent Intervention Team also shown to have significantly higher levels of BMCyt endpoints compared to other firefighters. Fire seasons are getting longer and dangerous, and this trend will continue in a progressive warming world. Implementing effective mitigation strategies for firefighters’ occupational exposure is an urgent public health issue.

2023-06-21Conference object

Restricted access

The Toxicity of Nanomaterials and Legacy Contaminants: Risks to the Environment and Human Health

Publication . Reis, Ana Teresa; Costa, Carla; Fraga, Sónia

Nanotechnology and the incorporation of nanomaterials (NM) into everyday products help to solve problems in society and improve the quality of life, allowing for major advances in the technological, industrial, and medical fields. Despite this positive and encouraging side of nanotechnology, the potential risks of NM to human health and the environment, as well as the ethical, legal, and social implications associated with nanotechnology, cannot be disregarded. Indeed, the same characteristics that make NM interesting from a technological application point of view may be undesirable upon their release into the environment. In fact, hundreds of tons of NM are released into the environment every year. The reduced dimensions of NM facilitate their diffusion into and transport through the atmosphere, water, and soil, and as well as their uptake and (bio)accumulation in organisms. Nanotoxicology has emerged as a discipline that seeks to assess the potential risk of NM, integrating knowledge and resources from material science, biology, toxicology, and analytical chemistry. Several studies have alerted us to the risks that certain NM represent for the environment and for our health, depending on their persistence and circulation in ecosystems, on the dose and responses of organisms to acute and chronic exposure to these substances, and on the ability of organisms to (bio)accumulate and/or excrete them. However, knowledge of the harmful effects of these contaminants of emerging concern is still insufficient, including mixture effects. Efforts to advance our knowledge on the reactivity of NM and their effects have been made using mostly in vitro and in vivo models; however, in recent years, in silico approaches and quantitative structure–activity relationship (QSAR) modeling have been gaining more attention. Nanotoxicity assessment using in vitro models gathers important information regarding the mechanism(s) of action of NM at the cellular and molecular levels. These models also offer the benefits of reduced costs and ethical concerns over animal welfare (3Rs principle), usually resulting in the faster toxicity screening of chemicals, an advantage considering the increasing number of materials and contaminant combinations to be tested. However, they lack the complexity and metabolic capabilities that in vivo models provide, which is important in identifying the relationship between exposure dose and the occurrence of adverse effects, and in understanding how the body handles NM in terms of their absorption, distribution, metabolism, and excretion (ADME). (...)

2023-07-21Periodical

Open access