Occupational Exposure during the Production and the Spray Deposition of Graphene Nanoplatelets-Based Polymeric Coatings.

Graphene-based polymer composites are innovative materials which have recently found wide application in many industrial sectors thanks to the combination of their enhanced properties. The production of such materials at the nanoscale and their handling in combination with other materials introduce growing concerns regarding workers' exposure to nano-sized materials. The present study aims to evaluate the nanomaterials emissions during the work phases required to produce an innovative graphene-based polymer coating made of a water-based polyurethane paint filled with graphene nanoplatelets (GNPs) and deposited via the spray casting technique. For this purpose, a multi-metric exposure measurement strategy was adopted in accordance with the harmonized tiered approach published by the Organization for Economic Co-operation and Development (OECD). As a result, potential GNPs release has been indicated near the operator in a restricted area not involving other workers. The ventilated hood inside the production laboratory guarantees a rapid reduction of particle number concentration levels, limiting the exposure time. Such findings allowed us to identify the work phases of the production process with a high risk of exposure by inhalation to GNPs and to define proper risk mitigation strategies.

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.

Airborne LTA Nanozeolites Characterization during the Manufacturing Process and External Sources Interaction with the Workplace Background.

Engineered nanoscale amorphous silica nanomaterials are widespread and used in many industrial sectors. Currently, some types of silicon-based nanozeolites (NZs) have been synthesized, showing potential advantages compared to the analogous micro-forms; otherwise, few studies are yet available regarding their potential toxicity. In this respect, the aim of the present work is to investigate the potential exposure to airborne Linde Type A (LTA) NZs on which toxicological effects have been already assessed. Moreover, the contributions to the background related to the main emission sources coming from the outdoor environment (i.e., vehicular traffic and anthropogenic activities) were investigated as possible confounding factors. For this purpose, an LTA NZ production line in an industrial factory has been studied, according to the Organisation for Economic Cooperation and Development (OECD) guidelines on multi-metric approach to investigate airborne nanoparticles at the workplace. The main emission sources of nanoparticulate matter within the working environment have been identified by real-time measurements (particle number concentration, size distribution, average diameter, and lung-deposited surface area). Events due to LTA NZ spillage in the air during the cleaning phases have been chemically and morphologically characterized by ICP-MS and SEM analysis, respectively.

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.

An integrated and multi-technique approach to characterize airborne graphene flakes in the workplace during production phases.

Graphene is a one-atom-thick sheet of carbon atoms arranged in a honeycomb pattern and its unique and amazing properties make it suitable for a wide range of applications ranging from electronic devices to food packaging. However, the biocompatibility of graphene is dependent on the complex interplay of its several physical and chemical properties. The main aim of the present study is to highlight the importance of integrating different characterization techniques to describe the potential release of airborne graphene flakes in a graphene processing and production research laboratory. Specifically, the production and processing (i.e., drying) of few-layer graphene (FLG) through liquid-phase exfoliation of graphite are analysed by integrated characterization techniques. For this purpose, the exposure measurement strategy was based on the multi-metric tiered approach proposed by the Organization for Economic Cooperation and Development (OECD) via integrating high-frequency real-time measurements and personal sampling. Particle number concentration, average diameter and lung deposition surface area time series acquired in the worker's personal breathing zone (PBZ) were compared simultaneously to background measurements, showing the potential release of FLG. Then, electron microscopy techniques and Raman spectroscopy were applied to characterize particles collected by personal inertial impactors to investigate the morphology, chemical composition and crystal structure of rare airborne graphene flakes. The gathered information provides a valuable basis for improving risk management strategies in research and industrial laboratories.

Occupational exposure to graphene and silica nanoparticles. Part I: workplace measurements and samplings.

Few-Layers Graphene (FLG) are able to improve the performance of materials, due to their chemical-physical properties. Engineered amorphous silica nanoparticles (SiO2NPs) are among the most widespread nanomaterials (NMs) in the world. Such nanomaterials are two case studies of the research project 'NanoKey' that integrated the exposure assessment through personal measurements and sampling in the workplace, as described in the present work (part I), with the biomonitoring of exposed workers (reported in part II). Measurement campaigns were conducted according to OECD and WHO harmonized approach in two production sites. The set of instruments included real-time devices for high-resolution measurements at the nanoscale and time-integrated samplers for the off-line gravimetric analysis and chemical and morphological (SEM-EDS) characterization of exposure in order to identify the contribution of production compared to the background. Values of particle number concentration (PNC) and lung deposited surface area (LDSA) within the FLG production resulted higher than the background far field (FF), even if they are always similar to the near field (NF) ones: the average diameter (Davg) during the production was higher than the NF background but always lower than the FF values. SEM-EDS analysis highlighted the presence of structures comparable to those produced. During the SiO2NPs production, the PBZ values showed PNC and LDSA levels higher than the background, with a decrease in the Davg probably due to NPs emission. SEM-EDS confirms the presence of rare silica nanoparticles. Since the exposure to airborne NMs cannot be excluded in both production sites, a prevention-through-design approach to mitigate the potential risk for workers has been recommended.

Workers' Exposure Assessment during the Production of Graphene Nanoplatelets in R&D Laboratory.

Widespread production and use of engineered nanomaterials in industrial and research settings raise concerns about their health impact in the workplace. In the last years, graphene-based nanomaterials have gained particular interest in many application fields. Among them, graphene nanoplatelets (GNPs) showed superior electrical, optical and thermal properties, low-cost and availability. Few and conflicting results have been reported about toxicity and potential effects on workers' health, during the production and handling of these nanostructures. Due to this lack of knowledge, systematic approaches are needed to assess risks and quantify workers' exposure to GNPs. This work applies a multi-metric approach to assess workers' exposure during the production of GNPs, based on the Organization for Economic Cooperation and Development (OECD) methodology by integrating real-time measurements and personal sampling. In particular, we analyzed the particle number concentration, the average diameter and the lung deposited surface area of airborne nanoparticles during the production process conducted by thermal exfoliation in two different ways, compared to the background. These results have been integrated by electron microscopic and spectroscopic analysis on the filters sampled by personal impactors. The study identifies the process phases potentially at risk for workers and reports quantitative information about the parameters that may influence the exposure in order to propose recommendations for a safer design of GNPs production process.

[Nanomaterials and occupational health: the INAIL research contribution for responsible innovation and risk prevention for workers in Italy]. / Nanomateriali e salute sul lavoro: il contributo dell'INAIL alla ricerca per l'innovazione responsabile e la tutela dei lavoratori in Italia.

SUMMARY: In the last years nanotechnologies and nanoproducts are constantly growing up thanks to their promising benefits for social and economic development. Nanomaterials are increasingly used in our daily life, finding application in many sectors such as textile, automotive, electronic, food, etc. In 2012, the European Commission included nanotechnologies among the Key Enabling Technologies (KETs), which provide the basis for innovation in the present century. In parallel to the growing interest at industrial and production level (estimated at about 11 million of tons per year) the number of workers potentially exposed in all nanomaterials life cycle has increased. Concurrently, concerns about the potential effects on human health arose, attracting the attention by the scientific community, in particular on health and safety issues in workplaces. In Italy the industrial market has evolved in the same direction with important economic investments both public and private. Consequently, numerous research groups belonging to the University, Institutions and Research Centers were involved in the study of the main issues to promote a responsible development of nanomaterials. In this framework, the main aim of this study is to highlight the commitment of Italian research in the field of health and safety of engineered nanomaterials, through the initiatives of Italian Workers Compensation Authority (INAIL) for sustainable development of nanotechnologies.

Workers' Exposure to Nano-Objects with Different Dimensionalities in R&D Laboratories: Measurement Strategy and Field Studies.

With the increasing interest in the potential benefits of nanotechnologies, concern is still growing that they may present emerging risks for workers. Various strategies have been developed to assess the exposure to nano-objects and their agglomerates and aggregates (NOAA) in the workplace, integrating different aerosol measurement instruments and taking into account multiple parameters that may influence NOAA toxicity. The present study proposes a multi-metric approach for measuring and sampling NOAA in the workplace, applied to three case studies in laboratories each dedicated to materials with different shapes and dimensionalities: graphene, nanowires, and nanoparticles. The study is part of a larger project with the aim of improving risk management tools in nanomaterials research laboratories. The harmonized methodology proposed by the Organization for Economic Cooperation and Development (OECD) has been applied, including information gathering about materials and processes, measurements with easy-to-use and hand-held real-time devices, air sampling with personal samplers, and off-line analysis using scanning electron microscopy. Significant values beyond which an emission can be attributed to the NOAA production process were identified by comparison of the particle number concentration (PNC) time series and the corresponding background levels in the three laboratories. We explored the relations between background PNC and microclimatic parameters. Morphological and elemental analysis of sampled filters was done to identify possible emission sources of NOAA during the production processes: rare particles, spherical, with average diameter similar to the produced NOAA were identified in the nanoparticles laboratory, so further investigation is recommended to confirm the potential for worker exposure. In conclusion, the information obtained should provide a valuable basis for improving risk management strategies in the laboratory at work.

Release of particles, organic compounds, and metals from crumb rubber used in synthetic turf under chemical and physical stress.

The chemical and morphological characteristics of materials released under chemical and physical stress by different rubber granulates used as infill materials in synthetic turf (recycled scrap tires, natural rubber, and a new-generation thermoplastic elastomer) were compared.The headspace solid-phase micro-extraction GC-MS analysis evidenced that at 70 °C natural rubber and thermoplastic elastomer release amounts of organic species much higher than recycled scrap tires. In particular, the desorption of mineral oils, with a prevalence of toxicologically relevant low-viscosity alkanes in the range C17-C22, and plasticizers (diisobutyl phthalate) was clearly evidenced. The new-generation thermoplastic elastomer material also releases butylated hydroxytoluene.In slightly acidic conditions, quite high amounts of bio-accessible Zn, Cu, and Co are released from recycled scrap tires, while natural rubber releases mainly Se and Tl. In contrast, the thermoplastic elastomer does not contain significant concentrations of leachable heavy metals.The formation of small particles, also in the inhalable fraction, was evidenced by electron microscopy after mechanical or thermal treatment of natural rubber.

Measurement techniques of exposure to nanomaterials in the workplace for low- and medium-income countries: A systematic review.

Nanotechnology offers many opportunities but there is still considerable uncertainty about the health risks and how to assess these.In the field of risk analysis for workers potentially exposed to nano-objects and their agglomerates and aggregates (NOAA) different methodological approaches to measure airborne NOAA have been proposed.This study proposes a systematic review of scientific literature on occupational exposure to NOAA in the workplace with the aim to identify techniques of exposure measurement to be recommended in low- and medium-income countries.We gathered scientific papers reporting techniques of NOAA exposure measurements in the workplace, we summarized the data for each eligible technique according to PRISMA guidelines, and we rated the quality of evidence following an adapted GRADE approach.We found 69 eligible studies to be included in qualitative synthesis: the majority of studies reported a moderate quality and only two studies demonstrated the use of a high quality exposure measurement technique.The review demonstrates that a basic exposure measurement, i.e. evidence for the presence or absence of NOAA in the workplace air, can be achieved with moderate (40 techniques) to high (2 techniques) quality; comprehensive exposure measurement, that allow the quantification of NOAA in the workplace, can be achieved with moderate (11 techniques) to high (2 techniques) quality.The findings of the study also allowed to finalize a list of requirements that must be fulfilled by an effective measurement technique (either basic or comprehensive) and to highlight the main weaknesses that need to be tackled for an effective affordability evaluation of measurement techniques to be recommended in low- and medium-income countries.

Cyto-genotoxic effects of smoke from commercial filter and non-filter cigarettes on human bronchial and pulmonary cells.

Cigarette smoke is a complex mixture of chemicals, some of which are known as carcinogens. The cyto-genotoxic effects of cigarette-smoke extract (CSE) from commercial cigarettes without (A and B) and with filter (C and D) were evaluated at different CSE concentrations on A549 and BEAS-2B cells. The particle content of the cigarette smoke and the metal composition of the CSE were also analyzed. The cells were exposed to 1-10% of the CSE from one cigarette per experiment. Cytotoxicity was evaluated by use of the MTT assay after 24h, and the lactate dehydrogenase (LDH) assay after 30min and 24h. The Fpg-modified comet assay was used to evaluate direct-oxidative DNA damage on cells exposed for 30min. As expected, unfiltered cigarette smoke (particularly from the B cigarette) contained a higher number of particles than filtered smoke. With smoke extract from the B cigarette we found a decrease in cell viability only in BEAS-2B cells. The results of the LDH test showed membrane damage for B-cigarette smoke extract, particularly in BEAS-2B cells. Extracts from unfiltered cigarette smoke induced significant direct DNA damage, to a larger extent in A549 cells. Filtered cigarette-smoke extract induced a significant direct DNA damage at 5-10%. A significant induction of oxidative DNA damage was found at the highest CSE concentration in both cell types (by smoke extracts from B and C cigarettes in A549 cells, and from A and D cigarettes in BEAS-2B cells). Smoke extracts from filter cigarettes induced less direct DNA damage than those from unfiltered cigarettes in A549 cells, probably due to a protective effect of filter. In BEAS-2B cells the smoke extract from the B-cigarette showed the highest genotoxic effect, with a concentration-dependent trend. These findings show a higher cyto-genotoxicity for smoke extracts from the B-cigarette and oxidative effects for those from the A and D cigarettes, particularly in BEAS-2B cells. Moreover, there was a higher responsiveness of A549 cells to genotoxic insult of CSE, and a cigarette-dependent genotoxicity in BEAS-2B cells. Our experimental model demonstrated to be suitable to sensitively detect early genotoxic response of different lung-cell types to non-cytotoxic concentrations of complex inhalable mixtures.

Multiparametric approach for an exemplary study of laser printer emissions.

The aim of this work was the study, by a multiparametric approach, of emissions from a laser printer in an experimental box-chamber, with particular attention to nanoparticles release. The experimental design included number concentration measurements by Fast Mobility Particle Sizer (FMPS) and chemical characterizations (elements) of size segregated samples collected by Nanomoudi cascade impactor. Volatile Organic Compounds (VOCs) were also sampled by charcoal sorbent tubes by personal sampling pumps. Monitoring of ozone, total volatile organic compounds concentrations and of temperature and humidity values inside the experimental box during the printing processes were also performed by automatic analyzers. The performed monitoring allowed to evidence different ways for particles emissions by laser printers, in particular showing that nanoparticles, characterised by high concentrations of Ba, Zn, B, K, Sr and Na, are set free at the beginning of the printing process. This emission seems to be directly ascribable to the use of toner powder, as all these elements are present in it. The emission of larger particles (ca. 100-320 nm) was observed in subsequent phases of the print process, probably due to the condensation of vapours released during the progressive heating of the fuser roller. This contribution was proved by both the FMPS measurements and the cascade impactor results. Also, a low emission of particles in higher size ranges was evidenced, mainly due to paper related particles. A very high concentration of VOCs was detected inside the chamber and the chemical speciation shows that the major contribution is associated to toner components, even if some species are released from other printer components. Although the formation of secondary species by reaction of VOCs with ozone cannot be excluded, these species were present inside the chamber at concentrations lower than the detection limit.