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In many industrial sectors, workers are exposed to manufactured or unintentionally emitted airborne nanoparticles (NPs). To develop prevention and enhance knowledge surrounding exposure, it has become crucial to achieve a consensus on how to assess exposure to airborne NPs by inhalation in the workplace. Here, we review the literature presenting recommendations on assessing occupational exposure to NPs. The 23 distinct strategies retained were analyzed in terms of the following points: target NPs, objectives, steps, "measurement strategy" (instruments, physicochemical analysis, and data processing), "contextual information" presented, and "work activity" analysis. The robustness (consistency of information) and practical aspects (detailed methodology) of each strategy were estimated. The objectives and methodological steps varied, as did the measurement techniques. Strategies were essentially based on NPs measurement, but improvements could be made to better account for "contextual information" and "work activity". Based on this review, recommendations for an operational strategy were formulated, integrating the work activity with the measurement to provide a more complete assessment of situations leading to airborne NP exposure. These recommendations can be used with the objective of producing homogeneous exposure data for epidemiological purposes and to help improve prevention strategies., Competing Interests: The authors declare no conflict of interest., (© 2023 Occupational Safety and Health Research Institute.)

The relevance of dustiness methods is increasingly recognized in the preliminary exposure evaluation of workers handling nanomaterials in powder form, and should also be transposed to the assessment of environmental risk in the future . The methods currently recommended in the European standards are mainly based on determining a mass-based dustiness index [mg kg -1 ], whereas surface area is regularly put forward as a more appropriate determinant to assess the pulmonary toxicity of nanoparticles. In this study, we describe an operational methodology leading us to propose a surface metric to determine the dustiness index [m 2 kg -1 ] of nanoparticulate matter. To this end, we demonstrate the equivalence between the external specific surface area of a nanopowder and that of its aerosol with five nanomaterials produced and used on an industrial scale, and covering a range of external specific surface areas from 35 to 230 m 2 g -1 . Compared to the conventional mass-based dustiness index, the surface-based dustiness index (1) is more discriminating, covering an additional order of magnitude, and (2) has an impact on the powder ranking with potential consequences on the preventive measures to be implemented. Finally, our proposal has the potential to be included in future revisions of European standards for workplace exposure and dustiness measurement, provided that further experimental results on surface-based dustiness indices support these preliminary data.

We demonstrate the relevance of the Volume Specific Surface Area (VSSA) parameter to identify the nanoparticulate character of powder mixes based on either spherical constituent particles with bimodal size distributions (TiO 2 ), or fiber-like constituent particles with unimodal size distributions (sepiolite and sepiolite-based pigments). These new results indicate that VSSA could reasonably be proposed as an optional criterion in the future for the definition of nanomaterials based on the European Commission recommendation, provided certain requirements are fulfilled., Competing Interests: There are no conflicts of interest to declare., (This journal is © The Royal Society of Chemistry.)

Despite recent concerns for workers' health, exposure situations to nanoparticles can occur in numerous workplaces. Understanding how exposures occur considering human work in these transformations remains a crucial issue of nanotechnologies. The objective of this article is to understand exposure situations to nanoparticles, their determinants and the resources to act on them. This understanding was achieved by specific measurement of nanoparticles aerosols, combined with an analysis of work activity (actions performed and physical strain) in a rubber industry. The presentation of real time measurements, associated with the video of work situations, during confrontation interviews becomes a means of making exposing work activities visible, to analyze and transform them from the points of view formulated by the company's stakeholders. In this way, characterized "typical exposure situations" serve to trigger discussions and open up new spaces for debate highlighting how innovation affects work and gives rise to enhanced prevention projects., Competing Interests: Declaration of competing interest The authors have no competing interests to declare., (Copyright © 2020 Elsevier Ltd. All rights reserved.)

Nanoparticulate powders are increasingly found in the workplace. Inhalation exposure to airborne nanoparticles (NPs) is possible throughout the life-cycle of the powders. As the toxicity of NPs has never been demonstrated, it remains essential to evaluate the risks associated with NPs in order to propose preventative measures. The first step of a risk assessment strategy consists in the identification of the 'nano' nature of a material, which suffers from a lack of an operational methodology. Here, we present a simplified and operational strategy relying on the volume specific surface area (VSSA) for nanomaterial identification, based on the recommendation stemming from the European Commission and previous work on this topic from the European Project Nanodefine. The proposed strategy was tested on a set of 15 representative industrial powders (TiO 2 , SiO 2 , CuO, and ZnO), covering a wide range of properties, and previous published data. The VSSA classification was validated via a comparison with the particle size obtained by transmission electron microscopy (TEM). It was evidenced that the VSSA is in accordance with particle size for nanomaterial powder classification. The proposed methodology involves relatively accessible methods such as thermogravimetric analysis, nitrogen adsorption and helium pycnometry and limits the detection of false negatives. Moreover, it does not imply systematic confirmation of the results with the reference particle size criterion. Our results suggest that the VSSA is a promising parameter to be used for risk assessment and should be further investigated on powder mixings to confirm its relevancy to define nanomaterial powders., Competing Interests: The authors confirm that there are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)

Nanomaterial powders and colloids are already a large industry and are expected to continue to grow rapidly. In the context of risk assessment associated with nanomaterials, characterization of nanoparticle size and morphology is required. Until now, the best method giving direct access to these parameters has been electron microscopy (EM), in particular, transmission electron microscopy (TEM). Although this method is widely used, several issues are highlighted such as cost, maintenance, sample representativity and damage for sensitive materials. Low-voltage transmission electron microscopes (LVTEMs) could be an alternative approach to solve some of these issues. This paper presents a first comparison between a benchtop LVTEM and a conventional device to determine the number size distribution of the constitutent particles of two polydispersed industrial powders (TiO 2 and SiO 2 ) with particle sizes close to 100 nm and two colloids referenced for their particle size (ERM FD 304 and NM 300 K). The samples were prepared with an optimized deposition protocol involving glow discharging and Alcian blue solution pre-treatment on the EM grids. The benchtop LVTEM produced a rather good resolution and the relative differences obtained for the median diameters D 50 are generally within ± 15 %. On the basis of these results, benchtop LVTEM could be promoted for identifying nanomaterials within the framework of risk assessment strategy., (Copyright © 2018 Elsevier Ltd. All rights reserved.)

Because nanomaterials have been increasingly developed and used in many technology and industry sectors over the last 20 years, an increasing number of workers is likely to be exposed to airborne nanoparticles. In addition, the question of the nanomaterial characteristics that should be assessed in epidemiological studies remains open. Thus, assessing occupational exposure to airborne nanoparticles will not only rely on mass concentration and chemical composition. Rather, key parameters, such as particle size, have to be included in measurement strategies. We previously proposed a methodology to estimate the Count Median Diameter (CMD) of an aerosol based on the simultaneous size-integrated measurement of two particle concentrations, lung-deposited surface area, and number, thanks to field-portable, commercially available aerosol instruments (Nanoparticle Surface Area Monitor/Condensation Particle Counter combination). In addition to previous work, this study investigates the case of various polydisperse metal oxides, organic oil, and salt particles with CMDs ranging from 16-410 nm. Once corrected, the CMDs derived from the NSAM/CPC agree within ±20% with regard to the reference electrical mobility equivalent diameter, regardless of aerosol composition, morphology, or geometric standard deviation (GSD). Furthermore, the field-applicability of the method was tested through 6 sets of experimental data stemming from workplace measurement campaigns where different materials were produced and handled (TiO 2 , SiO 2 , Ag, Multi-Walled Carbon Nanotubes-MWCNT), covering a range of CMDs between 40 and 190 nm. All situations considered, the approach based on the combination of a NSAM and a CPC leads to a satisfying estimation of particle CMD, within ±20% compared to reference CMD.

The relatively recent development of industries working with nanomaterials has created challenges for exposure assessment. In this article, we propose a relatively simple approach to assessing nanomaterial exposures for the purposes of epidemiological studies of workers in these industries. This method consists of an onsite industrial hygiene visit of facilities carried out individually and a description of workstations where nano-objects and their agglomerates and aggregates (NOAA) are present using a standardized tool, the Onsite technical logbook. To assess its reliability, we implemented this approach for assessing exposure to NOAA in workplaces at seven workstations which synthesize and functionalize carbon nanotubes. The prediction of exposure to NOAA using this method exhibited substantial agreement with that of the reference method, the latter being based on an onsite group visit, an expert's report and exposure measurements (Cohen kappa = 0.70, sensitivity = 0.88, specificity = 0.92). Intramethod comparison of results for exposure prediction showed moderate agreement between the three evaluators (two program team evaluators and one external evaluator) (weighted Fleiss kappa = 0.60, P = 0.003). Interevaluator reliability of the semiquantitative exposure characterization results was excellent between the two evaluators from the program team (Spearman rho = 0.93, P = 0.03) and fair when these two evaluators' results were compared with the external evaluator's results. The project was undertaken within the framework of the French epidemiological surveillance program EpiNano. This study allowed a first reliability assessment of the EpiNano method. However, to further validate this method a comparison with robust quantitative exposure measurement data is necessary., (© The Author 2017. Published by Oxford University Press on behalf of the British Occupational Hygiene Society.)

In addition to chemical composition, particle concentration and size are among the main parameters used to characterize exposure to airborne ultrafine or nanoparticles. To assess occupational inhalation exposure, real-time instruments are recommended in recent strategies published. Among portable devices for personal exposure assessment in the workplace, DiSCmini (Matter Aerosol AG, Switzerland) has been identified as a potential candidate with its capacity to measure the airborne nanoparticle concentration and average particle size with good time-resolution. Monodisperse and polydisperse test nanoaerosols of varying compositions and morphologies were produced in the laboratory using the CAIMAN facility. These aerosols covered a range of particle sizes between 15 and 400 nm and number concentrations from 700 to 840,000 cm(-3). The aerosols were used to investigate the behavior of DiSCmini, comparing experimental data to reference data. In spite of a slight tendency to underestimate particle size, all particle diameters, number concentrations and surface area concentrations measured were in the same order of magnitude as reference data. Furthermore, no significant effect due to particle composition or morphology was noted.

Potential differences in the toxicological properties of nanosized and non-nanosized particles have been notably pointed out for titanium dioxide (TiO(2)) particles, which are currently widely produced and used in many industrial areas. Nanoparticles of the iron oxides magnetite (Fe(3)O(4)) and hematite (Fe(2)O(3)) also have many industrial applications but their toxicological properties are less documented than those of TiO(2). In the present study, the in vitro cytotoxicity and genotoxicity of commercially available nanosized and microsized anatase TiO(2), rutile TiO(2), Fe(3)O(4), and Fe(2)O(3) particles were compared in Syrian hamster embryo (SHE) cells. Samples were characterized for chemical composition, primary particle size, crystal phase, shape, and specific surface area. In acellular assays, TiO(2) and iron oxide particles were able to generate reactive oxygen species (ROS). At the same mass dose, all nanoparticles produced higher levels of ROS than their microsized counterparts. Measurement of particle size in the SHE culture medium showed that primary nanoparticles and microparticles are present in the form of micrometric agglomerates of highly poly-dispersed size. Uptake of primary particles and agglomerates by SHE exposed for 24 h was observed for all samples. TiO(2) samples were found to be more cytotoxic than iron oxide samples. Concerning primary size effects, anatase TiO(2), rutile TiO(2), and Fe(2)O(3) nanoparticles induced higher cytotoxicity than their microsized counterparts after 72 h of exposure. Over this treatment time, anatase TiO(2) and Fe(2)O(3) nanoparticles also produced more intracellular ROS compared to the microsized particles. However, similar levels of DNA damage were observed in the comet assay after 24 h of exposure to anatase nanoparticles and microparticles. Rutile microparticles were found to induce more DNA damage than the nanosized particles. However, no significant increase in DNA damage was detected from nanosized and microsized iron oxides. None of the samples tested showed significant induction of micronuclei formation after 24 h of exposure. In agreement with previous size-comparison studies, we suggest that in vitro cytotoxicity and genotoxicity induced by metal oxide nanoparticles are not always higher than those induced by their bulk counterparts.

In the frame of assessing exposure to nanostructured particles, the aim of this work is to study the performance of a new device devoted to the real-time measurement of nanostructured aerosol: the meDiSC (Diffusion Size Classifier, Matter Engineering, Switzerland). This instrument is based on unipolar diffusion charging of particles which are then collected successively in diffusion and filtration stages. From currents measured in these stages, the instrument is capable of determining aerosol mean size and number concentration. These data were compared to reference measurements regarding monodisperse aerosols in a range from 20 to 700 nm; the relative biases were found unsatisfying. This led us to investigate the principle of the instrument. Consequently, the charging law of the diffusion charger was experimentally established, as well as the calibration curve allowing the determination of the mean size of the particles. The latter analysis was completed by a model based on diffusion theory. Our results indicate the possibility to improve the range of size measurement up to 350 nm. Measured particle size and number concentration were also used to calculate geometric surface-area concentration; the experimental data were compared to a reference calculated surface-area concentration. The results demonstrate the possibility to evaluate this parameter within acceptable uncertainty. In a second step, the meDiSC was challenged with polydisperse aerosols. It was observed that meDiSC overestimates particle size by a factor 1.7, while particle number concentrations are found within ±40% of the reference. The model applied to polydisperse aerosols indicates that polydispersity little influences particle size up to 300 nm while geometric standard deviation remains below 1.7., (This journal is © The Royal Society of Chemistry 2012)

Objective: Concern has been raised about the potential impact of nanomaterials exposure on human health, and France has decided to implement a timely epidemiological surveillance tool of workers likely to be exposed to engineered nanomaterials that could accompany the development of nanotechnologies., Methods: A comprehensive review of the toxicological and epidemiological literature has been conducted together with an exploratory study among French companies producing or handling nanoobjects., Results: A double surveillance system is proposed consisting of a prospective cohort survey and repeated cross-sectional studies. The aim of the cohort is (1) to monitor long-term health effects and (2) to allow of further research. Setting-up an exposure registry is the first planned step., Conclusions: The protocol is about to be submitted to the French Government for approval and funding.

Assessment of inhalable dust exposure requires reliable sampling methods in order to measure airborne inhalable particles' concentrations. Many inhalable aerosol samplers can be used but their performances widely vary and remain unknown in some cases. The sampling performance of inhalable samplers is strongly dependent on particle size and ambient air velocity. Five inhalable aerosol samplers have been studied in two laboratory wind tunnels using polydisperse glass-beads' test aerosol. Samplers tested were IOM sampler (UK), two versions of CIP 10-I sampler, v1 and v2 (F), 37-mm closed face cassette sampler (USA), 37-mm cassette fitted up with an ACCU-CAP insert (USA), and Button sampler (USA). Particle size-dependent sampling efficiencies were measured in a horizontal wind tunnel under a 1 m s(-1) wind velocity and in a vertical tunnel under calm air, using a specific method with Coulter(R) counter particle size number distribution determinations. Compared with CEN-ISO-ACGIH sampling criteria for inhalable dust, the experimental results show fairly high sampling efficiency for the IOM and CIP 10-I v2 samplers and slightly lower efficiencies for the Button and CIP 10-I v1 samplers. The closed face cassette (4-mm orifice) produced the poorest performances of all the tested samplers. This can be improved by using the ACCU-CAP internal capsule, which prevents inner wall losses inside the cassette. Significant differences between moving air and calm air sampling efficiency were observed for all the studied samplers.

Several samplers (IOM, CIP 10-I v1, ACCU-CAP, and Button) were evaluated at various wood industry companies using the CALTOOL system. The results obtained show that compared to the CALTOOL mouth, which can be considered to be representative of the exposure of a person placed at the same location under the same experimental conditions, the concentrations measured by the IOM, CIP 10-I v1, and ACCU-CAP samplers are not significantly different (respectively, 1.12, 0.94, and 0.80 compared to 1.00), the Button sampler (0.86) being close to the ACCU-CAP sampler. Comparisons of dust concentrations measured using both a closed-face cassette (CFC) and one of the above samplers were also made. In all, 235 sampling pairs (sampler + CFC) taken at six companies provided us with a comparison of concentrations measured using IOM, CIP 10-I v1, ACCU-CAP, and Button samplers with concentrations measured using a CFC. All the studied samplers collected systematically more dust than the CFC (2.0 times more for the IOM sampler, 1.84 times more for the CIP 10-I v1 sampler, 1.68 times more for the ACCU-CAP sampler, and 1.46 times more for the Button sampler). The literature most frequently compares the IOM sampler with the CFC: published results generally show larger differences compared with the CFC than those found during our research. There are several explanations for this difference, one of which involves CFC orientation during sampling. It has been shown that concentrations measured using a CFC are dependent on its orientation. Different CFC positions from one sampling session to another are therefore likely to cause differences during CFC-IOM sampler comparisons.

Annular aspiration slots were studied in laboratory conditions in order to investigate their performance in sampling airborne particles. The sampling efficiency was measured in a wind tunnel as a function of particle aerodynamic diameter in various conditions of external wind speed. The geometric parameters of the annular slot and the aerodynamic conditions of sampling were optimised in order to improve the sampling efficiency. Optimal selection of these parameters led to the sampling efficiency decreasing very slightly with increasing particle size. Two semi-empirical models of sampling efficiency--in moving and calm air conditions--were derived and experimentally checked. Omnidirectional annular sampling heads are less sensitive to the external wind and their inner particle losses can be minimised. A prototype of a personal aerosol sampler for exposure assessment in occupational safety and health was designed on the basis of these models. It broadly meets the conventional efficiency for inhalable aerosol sampling.

High concentrations of bioaerosols containing bacterial, fungal and biotoxinic matter are encountered in many workplaces, e.g. solid waste treatment plants, waste water treatment plants and sewage networks. A personal bioaerosol sampler, the CIP 10-M (M-microbiologic), has been developed to measure worker exposure to airborne biological agents. This sampler is battery operated; it is light and easy to wear and offers full work shift autonomy. It can sample much higher concentrations than biological impactors and limits the mechanical stress on the microorganisms. Biological particles are collected in 2 ml of liquid medium inside a rotating cup fitted with radial vanes to maintain an air flow rate of 10 l min(-1) at a rotational speed of approximately 7,000 rpm. The rotating cup is made of sterilisable material. The sampled particles follow a helicoidal trajectory as they are pushed to the surface of the liquid by centrifugal force, which creates a thin vertical liquid layer. Sterile water or another collecting liquid can be used. Three particle size selectors allow health-related aerosol fractions to be sampled according to international conventions. The sampled microbiological particles can be easily recovered for counting, incubation or further biochemical analysis, e.g., for airborne endotoxins. Its physical sampling efficiency was laboratory tested and field trials were carried out in industrial waste management conditions. The results indicate satisfactory collection efficiency, whilst experimental application has demonstrated the usefulness of the CIP 10-M personal sampler for individual bioaerosol exposure monitoring.

While personal aerosol samplers have been characterized primarily based on wind tunnel tests conducted at relatively high wind speeds, modern indoor occupational environments are usually represented by very slow moving air. Recent surveys suggest that elevated levels of occupational exposure to inhalable airborne particles are typically observed when the worker, operating in the vicinity of the dust source, faces the source. Thus, the first objective of this study was to design and test a new, low cost experimental protocol for measuring the sampling efficiency of personal inhalable aerosol samplers in the vicinity of the aerosol source when the samplers operate in very slowly moving air. In this system, an aerosol generator, which is located in the centre of a room-sized non-ventilated chamber, continuously rotates and omnidirectionally disperses test particles of a specific size. The test and reference samplers are equally distributed around the source at the same distance from the centre and operate in parallel (in most of our experiments, the total number of simultaneously operating samplers was 15). Radial aerosol transport is driven by turbulent diffusion and some natural convection. For each specific particle size and the sampler, the aerosol mass concentration is measured by weighing the collection filter. The second objective was to utilize the new protocol to evaluate three widely used aerosol samplers: the IOM Personal Inhalable Sampler, the Button Personal Inhalable Aerosol Sampler and the 25 mm Millipore filter holder (closed-face C25 cassette). The sampling efficiencies of each instrument were measured with six particle fractions, ranging from 6.9 to 76.9 micro m in their mass median aerodynamic diameter. The Button Sampler efficiency data demonstrated a good agreement with the standard inhalable convention and especially with the low air movement inhalabilty curve. The 25 mm filter holder was found to considerably under-sample the particles larger than 10 micro m; its efficiency did not exceed 7% for particles of 40-100 micro m. The IOM Sampler facing the source was found to over-sample compared with the data obtained previously with a slowly rotating, freely suspended sampler in a low air movement environment. It was also found that the particle wall deposition in the IOM metallic cartridge was rather significant and particle size-dependent. For each sampler (IOM, Button and C25) the precision was characterized through the relative standard deviation (RSD) of the aerosol concentration obtained with identical samplers in a specific experiment. The average RSD was 14% for the IOM Sampler, 11% for the Button Sampler and 35% for the 25 mm filter cassette. A separate set of experiments, performed with the Simplified Torso showed that in very slowly moving air a personal sampler can be adequately evaluated even when it is not attached to a body but freely suspended (confirming the data reported previously).