Experimental factors influencing the bioaccessibility and the oxidative potential of transition metals from welding fumes.

Inhalation of welding fumes (WFs) containing high levels of transition metals (Cr, Cu, Fe, Mn, Ni…) is associated with numerous health effects including oxidative stress. However, the measurements of the oxidative potential (OP) and bioaccessibility of WF transition metals depend on several physicochemical parameters and may be subject to several experimental artifacts. In this work, we investigated the influence of the experimental conditions that may affect the bioaccessibility of transition metals and their OP on stainless-steel WF extracts. WFs were produced using a generation bench and sampled on filters. The soluble fraction of the metals was analysed. Two different extraction fluids mimicking physiological pulmonary conditions were studied: phosphate buffer and Hatch's solution. Three extraction times were tested to determine the optimal time for a significant OPDTT using the dithiothreitol (DTT) method. The storage conditions of WFs after filter sampling such as duration, temperature and atmospheric conditions were investigated. The results indicate that experimental conditions can significantly affect the OPDTT and metal bioaccessibility analyses. Cr, Cu and Ni show higher solubility in Hatch's solution than in the phosphate buffer. Mn is highly sensitive to DTT and shows close solubility in the two fluids. An extraction time of 0.5 h in phosphate buffer allows a better sensitivity to OPDTT, probably by limiting complexations, interactions between metals and precipitation. Storage time and temperature can influence the physical or chemical evolution of the WFs, which can affect their OPDTT and Mn solubility. However, storage under N2(g) limits these changes. On-line measurements of OPDTT could provide an alternative to filter sampling to overcome these artifacts.

Characterizing particle emissions from a direct energy deposition additive manufacturing process and associated occupational exposure to airborne particles.

This study aims to characterize airborne particles emitted from a metal additive manufacturing machine and related levels of occupational exposure. To achieve this, a complete measurement methodology was deployed around a direct energy deposition machine. Different operating conditions were investigated, based on configurations of two materials and two injection nozzles. Two replicates were performed for each condition. Airborne particles emitted during repeated manufacturing cycles were measured simultaneously at the source, in the near field, in the far field and on the operator. Real-time instruments were used to characterize the machine emissions (10 nm-10 µm) associated with respirable and inhalable samplers and cascade impactors. Measurements were made during both the manufacturing process and transient operating phases. In parallel, personal exposure to hexavalent chromium was assessed. The number of particles measured for the different machining phases show that high levels of particles (> 5 × 105 # cm-3, 0.3-1.3 mg m-3 inhalable particles, 0.2-6 µg m-3 CrVI) were emitted in the machine enclosure. The size distributions indicate that more than 90% of the particles are smaller than 250 nm. Occupational exposure to CrVI was found to be below the LOQ of 0.098 µg m-3 for the two alloys investigated. During the machining process, near-field number and mass concentrations were ∼ 104 # cm-3, and below 0.04 mg m-3, respectively. Far-field number concentrations were also on the order of 104 # cm-3 throughout the whole monitoring period. The transient phase of door opening was found to result in high levels of exposure (> 105 # cm-3), which were also detected in the near-field, confirming the need to implement preventative actions. To address this issue, a collective protective measure, consisting of setting a time delay of about 8 min between the end of the manufacturing process and opening of the door, could be employed. This collective measure should also be accompanied by the wearing of personal protective equipment by the operator when an intervention in the machine enclosure is necessary.

Occupational exposure to beryllium in French industries.

Beryllium (Be) is a metal mainly used in the form of alloys, with copper (Cu) and aluminium (Al) in the metal industry. Be is an extremely toxic element which must be handled under strictly controlled conditions to avoid health hazards to workers. Exposure to Be can be responsible for Chronic Beryllium Disease, a pulmonary disease preceded by sensitization to the element, and for lung cancer. The goals of the current study were to investigate Be exposure in France, to determine the airborne Be occupational exposure levels, the associated impregnation of employees through their urinary Be levels and the factors that might affect them, and finally to study a possible relation between biomonitoring and airborne data. Seventy-five volunteer subjects were thus atmospherically and biologically monitored in five French companies involved in Cu or Al casting, Al smelting, CuBe machining or AlBe general mechanical engineering. Airborne exposure was quite low with only 2% of measurements above the current French Occupational Exposure Limit (2 µg/m3); the population potentially most exposed was foundry workers. Impregnation with Be was also low with only 10% of quantified urinary Be measurements above the current German BAR value (0.05 µg/L). Using a Bayesian statistical modelling approach, the mean subject-specific urinary excretion of Be was found to increase significantly with the mean subject-specific exposure to airborne Be. From this relationship, and based on the current French OEL-8 hr, a Biological Limit Value of 0.08 µg/L (= 0.06 µg/g creatinine) could be proposed.

Effects of occupational exposure to poorly soluble forms of beryllium on biomarkers of pulmonary response in exhaled breath of workers in machining industries.

OBJECTIVE: To analyze the effects of occupational exposure to poorly soluble forms of beryllium (Be) on biomarkers of pulmonary inflammation using exhaled breath condensate (EBC) in workers employed in machining industries. METHODS: Twenty machining operators were compared to 16 controls. The individual exposure to Be was assessed from the work history with several indices of exposure calculated on the basis of task-exposures matrices developed for each plant using historical air measurements. Clinical evaluation consisted in a medical questionnaire, measurements of biomarkers in EBC (tumor necrosis factor alpha (TNF-α), total nitrogen oxides (NOx)), measurement of the fraction of exhaled nitric oxide (FeNO) and resting spirometry. Adjusted multiple linear regressions were used to study the effect of the exposure to Be on inflammatory biomarkers. RESULTS: Levels of TNF-α and NOx in EBC were not statistically different between exposed and controls. We found a statistically significant relationship between levels of TNF-α in EBC and both index of cumulative exposure and duration of exposure to Be. No other statistically significant relationships were found between exposure to Be and pulmonary response. CONCLUSION: Our results suggest that machining-related exposure to Be is related to pulmonary inflammation involving TNF-α. These findings must be confirmed by larger studies.

Beryllium solubility in occupational airborne particles: Sequential extraction procedure and workplace application.

Modification of an existing sequential extraction procedure for inorganic beryllium species in the particulate matter of emissions and in working areas is described. The speciation protocol was adapted to carry out beryllium extraction in closed-face cassette sampler to take wall deposits into account. This four-step sequential extraction procedure aims to separate beryllium salts, metal, and oxides from airborne particles for individual quantification. Characterization of the beryllium species according to their solubility in air samples may provide information relative to toxicity, which is potentially related to the different beryllium chemical forms. Beryllium salts (BeF(2), BeSO(4)), metallic beryllium (Bemet), and beryllium oxide (BeO) were first individually tested, and then tested in mixtures. Cassettes were spiked with these species and recovery rates were calculated. Quantitative analyses with matched matrix were performed using inductively coupled plasma mass spectrometry (ICP-MS). Method Detection Limits (MDLs) were calculated for the four matrices used in the different extraction steps. In all cases, the MDL was below 4.2 ng/sample. This method is appropriate for assessing occupational exposure to beryllium as the lowest recommended threshold limit values are 0.01 µg.m(-3) in France([) (1) (]) and 0.05 µg.m(-3) in the USA.([ 2 ]) The protocol was then tested on samples from French factories where occupational beryllium exposure was suspected. Beryllium solubility was variable between factories and among the same workplace between different tasks.

Beryllium in exhaled breath condensate as a biomarker of occupational exposure in a primary aluminum production plant.

OBJECTIVE: Low beryllium exposure can induce pulmonary granulomatosis, so called berylliosis. For occupational health monitoring, it is more relevant to assess the internal dose of Be received by the lungs than urinary or atmospheric Be. Exhaled breath condensate (EBC) is a matrix collected non-invasively that derives from the airway lining fluid. EBC beryllium (Be) levels were evaluated as a marker of occupational exposure in a primary aluminum production plant. METHODS: We collected urine and EBC from controls and workers recently exposed to beryllium in the pot room and the anode repair sectors, and calculated a cumulative beryllium exposure index (CBEI) summing the number of years of employment in each task and multiplying by the estimated average beryllium exposure for the task. Concentrations of beryllium and aluminum were measured in EBC (Be-EBC and Al-EBC) and in urine (Be-U and Al-U) by ICP-MS. RESULTS AND CONCLUSION: We have shown that it was possible to measure Be and Al in workers' EBC. Compared with controls and after adjustment for smoking status, levels of Be-EBC and Al-EBC were higher in pot room workers and exposed subjects, respectively. Due to its relationship with CBEI, but not with Be-U, it appears that Be-EBC could be a promising marker of occupational exposure and provide additional toxicokinetic information in occupational health studies.

Occupational exposure to chrome VI compounds in French companies: results of a national campaign to measure exposure (2010-2013).

A campaign to measure exposure to hexavalent chromium compounds was carried out in France by the seven CARSAT chemistry laboratories, CRAMIF laboratory, and INRS over the 2010-2013 period. The survey included 99 companies involved in various activity sectors. The inhalable fraction of airborne particles was sampled, and exposure levels were determined using ion chromatography analysis combined with post-column derivatization and UV detection. The quality of the measurement results was guaranteed by an inter-laboratory comparison system involving all the laboratories participating in this study. Exposure levels frequently exceeded the French occupational exposure limit value (OELV) of 1 µg m(-3), in activities such as thermal metallization and manufacturing and application of paint in the aeronautics sector. The results also reveal a general trend for a greater proportion of soluble Chromium VI (Cr VI) compounds compared with insoluble compounds. Qualitative and quantitative information relating to the presence of other metallic compounds in the air of workplaces is also provided, for example for Cr III, Ni, Fe, etc. The sampling strategy used and the measurement method are easy to implement, making it possible to check occupational exposure with a view to comparing it to an 8 h-OELV of 1 µg m(-3).

Cytotoxicity and genotoxicity of nanosized and microsized titanium dioxide and iron oxide particles in Syrian hamster embryo cells.

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.

Evaluation of sampling methods for measuring exposure to volatile inorganic acids in workplace air. Part 2: Sampling capacity and breakthrough tests for sodium carbonate-impregnated filters.

In France, the MétroPol 009 method used to measure workplace exposure to inorganic acids, such as HF, HCl, and HNO3, consists of a closed-face cassette fitted with a prefilter to collect particles, and two sodium carbonate-impregnated filters to collect acid vapor. This method was compared with other European methods during the development of a three-part standard (ISO 21438) on the determination of inorganic acids in workplace air by ion chromatography. Results of this work, presented in a companion paper, led to a need to go deeper into the performance of the MétroPol 009 method regarding evaluation of the breakthrough of the acids, both alone and in mixtures, interference from particulate salts, the amount of sodium carbonate required to impregnate the sampling filter, the influence of sampler components, and so on. Results enabled improvements to be made to the sampling device with respect to the required amount of sodium carbonate to sample high HCl or HNO3 concentrations (500 µL of 5% Na2CO3 on each of two impregnated filters). In addition, a PVC-A filter used as a prefilter in a sampling device showed a propensity to retain HNO3 vapor so a PTFE filter was considered more suitable for use as a prefilter. Neither the material of the sampling cassette (polystyrene or polypropylene) nor the sampling flowrate (1 L/min or 2 L/min) influenced the performance of the sampling device, as a recovery of about 100% was achieved in all experiments for HNO3, HCl, and HF, as well as HNO3+HF and HNO3+HCl mixtures, over a wide range of concentrations. However, this work points to the possibility of interference between an acid and salts of other acids. For instance, interference can occur through interaction of HNO3 with chloride salts: the stronger the acid, the greater the interference. Methods based on impregnated filters are reliable for quantitative recovery of inorganic volatile acids in workplace atmosphere but are valuable only in the absence of interferents.

Evaluation of sampling methods for measuring exposure to volatile inorganic acids in workplace air. Part 1: sampling hydrochloric acid (HCl) and nitric acid (HNO3) from a test gas atmosphere.

Historically, workplace exposure to the volatile inorganic acids hydrochloric acid (HCl) and nitric acid (HNO(3)) has been determined mostly by collection on silica gel sorbent tubes and analysis of the corresponding anions by ion chromatography (IC). However, HCl and HNO(3) can be present in workplace air in the form of mist as well as vapor, so it is important to sample the inhalable fraction of airborne particles. As sorbent tubes exhibit a low sampling efficiency for inhalable particles, a more suitable method was required. This is the first of two articles on "Evaluation of Sampling Methods for Measuring Exposure to Volatile Inorganic Acids in Workplace Air" and describes collaborative sampling exercises carried out to evaluate an alternative method for sampling HCl and HNO(3) using sodium carbonate-impregnated filters. The second article describes sampling capacity and breakthrough tests. The method was found to perform well and a quartz fiber filter impregnated with 500 µL of 1 M Na(2)CO(3) (10% (m/v) Na(2)CO(3)) was found to have sufficient sampling capacity for use in workplace air measurement. A pre-filter is required to remove particulate chlorides and nitrates that when present would otherwise result in a positive interference. A GSP sampler fitted with a plastic cone, a closed face cassette, or a plastic IOM sampler were all found to be suitable for mounting the pre-filter and sampling filter(s), but care has to be taken with the IOM sampler to ensure that the sampler is tightly closed to avoid leaks. HCl and HNO(3) can react with co-sampled particulate matter on the pre-filter, e.g., zinc oxide, leading to low results, and stronger acids can react with particulate chlorides and nitrates removed by the pre-filter to liberate HCl and HNO(3), which are subsequently collected on the sampling filter, leading to high results. However, although there is this potential for both positive and negative interferences in the measurement, these are unavoidable. The method studied has now been published in ISO 21438-2:2009.