Evaluation of Systemic Genotoxic/Oxidative and Proinflammatory Effects in Workers of a Titanium Dioxide Production Plant.

This study is aimed at evaluating whether the occupational exposure to TiO2 during the industrial production process is able to induce genotoxic, oxidative, and inflammatory effects on blood, biomonitoring the same workers that showed micronucleus induction in the exfoliated buccal cells, as previous published. The final aim was to find sensitive and suitable biomarkers to evaluate potential early toxicity of occupational exposure to TiO2. On the same 40 workers involved in the manufacture of TiO2 pigment, 5 office workers, and 18 controls previously studied, we used formamidopyrimidine glycosylase- (Fpg-) comet assay on lymphocytes to evaluate genotoxic/oxidative effects and detected cytokine (IL-6, IL-8, and TNFα) release by ELISA to evaluate proinflammation. Moreover, we studied the possible influence of single nucleotide polymorphisms of XRCC1 and hOGG1 DNA repair genes and of GST metabolism-related genes (GSTT1 and GSTM1) on the evaluated effects. We did not find statistically significant differences in the mean values of the analysed Fpg-comet assay parameters; only the percentage of DNA damaged cells appearing in the test as comets (% comets) resulted higher in the exposed workers compared to controls. Also, the data analysed taking into account the specific task (bagging, industrial cleaning, mobile operations, maintaining, and production) showed differences only for % comets which resulted higher in industrial cleaners compared to controls. We found variations of IL-6 and IL-8 levels in the exposed workers with concentrations that were lower for IL-6 and higher for IL-8 compared to the control group. XRCC1, hOGG1, and GSTT1 polymorphisms did not influence neither comet parameters nor cytokine release. These findings demonstrate that TiO2 production process is able to induce slight proinflammatory effects in terms of IL-8 increased release but not significant genotoxic/oxidative effects on lymphocytes, which do not seem to be a target of TiO2, prevalently inhalable particles, generated in the studied production site.

A follow-up study on workers involved in the graphene production process after the introduction of exposure mitigation measures: evaluation of genotoxic and oxidative effects.

During nanomaterial (NM) production, workers could be exposed, particularly by inhalation, to NMs and other chemicals used in the synthesis process, so it is important to have suitable biomarkers to monitor potential toxic effects. Aim of this study was to evaluate the effectiveness of the introduction of exposure mitigation measures on workers unintentionally exposed to graphene co-pollutants during production process monitoring the presumable reduction of workplace NM contamination and of early genotoxic and oxidative effects previously found on these workers. We used Buccal Micronucleus Cytome (BMCyt) assay and Fpg-comet test, resulted the most sensitive biomarkers on our first biomonitoring work, to measure the genotoxic effects. We also detected urinary oxidized nucleic acid bases 8-oxoGua, 8-oxoGuo and 8-oxodGuo to evaluate oxidative damage. The genotoxic and oxidative effects were assessed on the same graphene workers (N = 6) previously studied, comparing the results with those found in the first biomonitoring and with the control group (N = 11). This was achieved 6 months after the installation of a special filter hood (where to perform the phases at higher risk of NM emission) and the improvement of environmental and personal protective equipment. Particle number concentration decreased after the mitigation measures. We observed reduction of Micronucleus (MN) frequency and oxidative DNA damage and increase of 8-oxodGuo excretion compared to the first biomonitoring. These results, although limited by the small subject number, showed the efficacy of adopted exposure mitigation measures and the suitability of used sensitive and noninvasive biomarkers to bio-monitor over time workers involved in graphene production process.

New formaldehyde-free adhesives for wood manufacturing: In vitro evaluation of potential toxicity of fine dust collected during wood sawing using a new experimental model to simulate occupational inhalation exposure.

Formaldehyde mainly emitted from wood adhesives, finishing materials, paint for furniture represents, together with wood dust, a potential carcinogenic risk for wood workers. Aims of this multidisciplinary study are to investigate the possibility of replacing urea-formaldehyde (UF) adhesives in the wood industry with organic and/or inorganic-based glues to obtain a final less toxic product and to evaluate the potential toxicity of wood glued with such new adhesives. For this purpose we selected poplar wood to test an organic new adhesive HBP (Hemp Based Protein), a mixture of hemp flour and cross-linker PAE (polyaminoamide epichlorohydrin), and spruce wood to test an inorganic adhesive geopolymer K-PSS (potassium-polysiloxosialate) plus polyvinyl acetate. For the poplar wood, we also used a commercial panel glued with UF for comparison. We reproduced occupational inhalation exposure during sawing activities of mentioned woods, collected and characterized the wood dusts emitted during sawing and evaluated in vitro their potential cyto-genotoxic and inflammatory effects. We used human lung cells (A549) exposed for 24 h to 20 and 100 µg/mL of collected PM2.5 wood dust. We found that both the new adhesives wood dusts induced a slightly higher apoptotic effect than untreated natural wood dusts particularly in spruce wood. Only geopolymer K-PSS wood dust induced membrane damage at the highest concentration and direct and oxidative DNA damage that could be explained by the different chemical composition and the lower particle sizes in respect to organic HBP adhesive wood dust. We found slight induction of IL-6 release, not influenced by K-PSS treatment, at the highest concentration in spruce wood. For poplar wood, IL-6 and IL-8 induction was found particularly for untreated and UF-treated wood at the highest concentration, where hemp adhesive treatment induced lower inflammation while at lower concentration similar slight cytokine induction was found for all tested wood dusts. This preliminary study shows that natural adhesives used to replace UF adhesives represent an interesting alternative, particularly the organic hemp-based adhesive showing very low toxicity.

Occupational exposure to graphene and silica nanoparticles. Part II: pilot study to identify a panel of sensitive biomarkers of genotoxic, oxidative and inflammatory effects on suitable biological matrices.

The available biomonitoring studies on workers producing/handling nanomaterials (NMs) focused on potential effects on respiratory, immune and cardio-vascular system. Aim of this study was to identify a panel of sensitive biomarkers and suitable biological matrices to evaluate particularly genotoxic and oxidative effects induced on workers unintentionally exposed to graphene or silica nanoparticles during the production process. These nanomaterials have been chosen for 'NanoKey' project, integrating the workplace exposure assessment (reported in part I) with the biomonitoring of exposed workers reported in the present work. Simultaneously to workplace exposure characterization, we monitored the workers using: Buccal Micronucleus Cytome (BMCyt) assay, fpg-comet test (lymphocytes), oxidized DNA bases 8-oxoGua, 8-oxoGuo and 8-oxodGuo measurements (urine), analysis of oxidative stress biomarkers in exhaled breath condensate (EBC), FENO measurement and cytokines release detection (serum). Since buccal cells are among the main targets of NM occupational exposure, particular attention was posed to the BMCyt assay that represents a noninvasive assay. This pilot study, performed on 12 workers vs.11 controls, demonstrates that BMCyt and fpg-comet assays are the most sensitive biomarkers of early, still reparable, genotoxic and oxidative effects. The findings suggest that these biomarkers could represent useful tools for the biomonitoring of workers exposed to nanoparticles, but they need to be confirmed on a high number of subjects. However, such biomarkers don't discriminate the effects of NM from those due to other chemicals used in the NM production process. Therefore, they could be suitable for the biomonitoring of workers exposed to complex scenario, including nanoparticles exposure.

Cyto-genotoxic and inflammatory effects of commercial Linde Type A (LTA) nanozeolites on human alveolar epithelial cells.

Nanozeolites (NZs) are increasingly used in several sectors, including catalysts, ion exchange materials or thermal isolators, taking advantage of the major property of NZs to absorb residual water and moisture to preserve the insulation of devices and products, but very few data are available on their toxicity. We investigated the potential cyto-genotoxicity and pro-inflammatory effects of manufactured Linde Type A (LTA)-NZs on human alveolar cells (A549) exposed to 10, 25, 50 and 100 µg/mL. LTA NZs were characterized by dynamic light scattering (DLS). Cell viability, mortality and apoptosis were evaluated by cytofluorimetric assay after 24h exposure. Membrane damage was evaluated by lactate dehydrogenase release and direct and oxidative DNA damage induction by formamide-pyrimidine glycosylase-Comet assay after 4 and 24 h. The induction of pro-inflammatory effects was evaluated in terms of interleukin 6 (IL-6) and IL-8 cytokine release after 24 h by ELISA. We found a slight increase in apoptotic cell percentage at 50 and 100 µg/mL and dead cell percentage at 100 µg/mL after 24 h; slight, but statistically significant, direct DNA damage starting from 25 µg/mL and slight oxidative DNA damage both at 4 and at 24 h; increased release of IL-6 only at the lowest concentration after 24 h. The results show lack of cytotoxicity, early moderate genotoxicity and slight inflammatory effects at the lowest used concentration. These findings represent the first data on potential genotoxic, oxidative and inflammatory effects of LTA NZs and highlight the need to perform further studies to confirm such results.