Jean-Jacques Sauvain

Characterization of lead-recycling facility emissions at various workplaces: Major insights for sanitary risks assessment

Most available studies on lead smelter emissions deal with the environmental impact of outdoor particles, but only a few focus on air quality at workplaces. The objective of this study is to physically and chemically characterize the Pb-rich particles emitted at different workplaces in a lead recycling plant. A multi-scale characterization was conducted from bulk analysis to the level of individual particles, to assess the particles properties in relation with Pb speciation and availability. Process PM from various origins were sampled and then compared; namely Furnace and Refining PM respectively present in the smelter and at refinery workplaces, Emissions PM present in channeled emissions. These particles first differed by their morphology and size distribution, with finer particles found in emissions. Differences observed in chemical composition could be explained by the industrial processes. All PM contained the same major phases (Pb, PbS, PbO, PbSO(4) and PbO·PbSO(4)) but differed on the nature and amount of minor phases. Due to high content in PM, Pb concentrations in the CaCl(2) extractant reached relatively high values (40 mg L(-1)). However, the ratios (soluble/total) of CaCl(2) exchangeable Pb were relatively low (<0.02%) in comparison with Cd (up to 18%). These results highlight the interest to assess the soluble fractions of all metals (minor and major) and discuss both total metal concentrations and ratios for risk evaluations. In most cases metal extractability increased with decreasing size of particles, in particular, lead exchangeability was highest for channeled emissions. Such type of study could help in the choice of targeted sanitary protection procedures and for further toxicological investigations. In the present context, particular attention is given to Emissions and Furnace PM. Moreover, exposure to other metals than Pb should be considered.

In vitro assessment of the pulmonary toxicity and gastric availability of lead-rich particles from a lead recycling plant

Epidemiological studies in urban areas have linked increasing respiratory and cardiovascular pathologies with atmospheric particulate matter (PM) from anthropic activities. However, the biological fate of metal-rich PM industrial emissions in urban areas of developed countries remains understudied. Lead toxicity and bioaccessibility assessments were therefore performed on emissions from a lead recycling plant, using complementary chemical acellular tests and toxicological assays, as a function of PM size (PM(10-2.5), PM(2.5-1) and PM(1)) and origin (furnace, refining and channeled emissions). Process PM displayed differences in metal content, granulometry, and percentage of inhalable fraction as a function of their origin. Lead gastric bioaccessibility was relatively low (maximum 25%) versus previous studies; although, because of high total lead concentrations, significant metal quantities were solubilized in simulated gastrointestinal fluids. Regardless of origin, the finest PM(1) particles induced the most significant pro-inflammatory response in human bronchial epithelial cells. Moreover, this biological response correlated with pro-oxidant potential assay results, suggesting some biological predictive value for acellular tests. Pulmonary effects from lead-rich PM could be driven by thiol complexation with either lead ions or directly on the particulate surface. Finally, health concern of PM was discussed on the basis of pro-inflammatory effects, accellular test results, and PM size distribution.

Nanoparticle reactivity toward dithiothreitol

Hazard determination of nanoparticles (NP) is challenging and should be based on a predictive and pragmatic tier approach. The biological effects of NP appear to be related not only to surface/size but also to their ability to generate free radicals/oxidants. We propose that the measurement of this property by acellular assays could be helpful for NP toxicity screening. This study investigated the effect of dispersing conditions on the oxidative capacity of a small selection of carbonaceous NP toward dithiothreitol (DTT). Increasing surfactant concentration decreased the DTT reactivity on these studied particles. Afterward, a panel of NP were studied under constant conditions. Classification of the NP panel based on their DTT reactivity was found to be dependent on the metric used (mass or surface) but not on the surfactant type. The DTT assay may be useful for an initial evaluation of the hazardousness of manufactured or unintentionally produced NP. However, the predictive potential of such a test towards biological effects still needs to be evaluated.

Comparison of Three Acellular Tests for Assessing the Oxidation Potential of Nanomaterials

Great effort is put into developing reliable, predictive, high-throughput, and low-cost screening approaches for the toxicity evaluation of ambient and manufactured nanoparticles (NP). These tests often consider oxidative reactivity, as oxidative stress is a well-documented pathway in particle toxicology. Based on a panel of six carbonaceous and five metal/metal oxide (Me/MeOx) nanoparticles, we: (i) compared the specifications (linearity, detection limits, repeatability) of three acellular reactivity tests using either dithiothreitol (DTT assay), dichlorofluorescein (DCFH assay), or ascorbic acid (AA-assay) as the reducing agent; and (ii) evaluated which physicochemical properties were important for explaining the observed reactivity. The selected AA assay was found to be neither sensitive nor robust enough to be retained. For the other tests, the surface properties of carbonaceous NP were of utmost importance for explaining their reactivity. In particular, the presence of “strongly reducing” surface functions explained most of its DCFH reactivity and a large part of its DTT reactivity. For the selected Me/MeOx, a different picture emerged. Whereas all particles were able to oxidize DCFH, dissolution and complexation processes could additionally influence the measured reactivity, as observed using the DTT assay. This study suggests that a combination of the DTT and DCFH assays provides complementary information relative to the quantification of the oxidative capacity of NP. Copyright 2013 American Association for Aerosol Research

Exhaled Breath Condensate as a Matrix for Combustion-Based Nanoparticle Exposure and Health Effect Evaluation

BACKGROUND Health assessment and medical surveillance of workers exposed to combustion nanoparticles are challenging. The aim was to evaluate the feasibility of using exhaled breath condensate (EBC) from healthy volunteers for (1) assessing the lung deposited dose of combustion nanoparticles and (2) determining the resulting oxidative stress by measuring hydrogen peroxide (H(2)O(2)) and malondialdehyde (MDA). METHODS Fifteen healthy nonsmoker volunteers were exposed to three different levels of sidestream cigarette smoke under controlled conditions. EBC was repeatedly collected before, during, and 1 and 2 hr after exposure. Exposure variables were measured by direct reading instruments and by active sampling. The different EBC samples were analyzed for particle number concentration (light-scattering-based method) and for selected compounds considered oxidative stress markers. RESULTS Subjects were exposed to an average airborne concentration up to 4.3×10(5) particles/cm(3) (average geometric size ∼60-80 nm). Up to 10×10(8) particles/mL could be measured in the collected EBC with a broad size distribution (50(th) percentile ∼160 nm), but these biological concentrations were not related to the exposure level of cigarette smoke particles. Although H(2)O(2) and MDA concentrations in EBC increased during exposure, only H2O2 showed a transient normalization 1 hr after exposure and increased afterward. In contrast, MDA levels stayed elevated during the 2 hr post exposure. CONCLUSIONS The use of diffusion light scattering for particle counting proved to be sufficiently sensitive to detect objects in EBC, but lacked the specificity for carbonaceous tobacco smoke particles. Our results suggest two phases of oxidation markers in EBC: first, the initial deposition of particles and gases in the lung lining liquid, and later the start of oxidative stress with associated cell membrane damage. Future studies should extend the follow-up time and should remove gases or particles from the air to allow differentiation between the different sources of H(2)O(2) and MDA.

Quantitative Aspects of the Interfacial Catalytic Oxidation of Dithiothreitol by Dissolved Oxygen in the Presence of Carbon Nanoparticles

The catalytic nature of particulate matter is often advocated to explain its ability to generate reactive oxygen species, but quantitative data are lacking. We have performed molecular characterization of three different carbonaceous nanoparticles (NP) by 1. identifying and quantifying their surface functional groups based on probe gas-particle titration; 2. studying the kinetics of dissolved oxygen consumption in the presence of suspended NPs and dithiothreitol (DTT). We show that these NPs can reversibly change their oxidation state between oxidized and reduced functional groups present on the NP surface. By comparing the amount of O2 consumed and the number of strongly reducing sites on the NP, its average turnover ranged from 35 to 600 depending on the type of NP. The observed quadratic rate law for O2 disappearance points to a Langmuir-Hinshelwood surface-based reaction mechanism possibly involving semiquinone radical. In the proposed model, the strongly reducing surface site is assumed to be a polycyclic aromatic hydroquinone whose oxidation to the corresponding conjugated quinone is rate-limiting in the catalytic chain reaction. The presence and strength of the reducing surface functional groups are important for explaining the catalytic activity of NP in the presence of oxygen and a reducing agent like DTT.

Benchmark of Nanoparticle Tracking Analysis on Measuring Nanoparticle Sizing and Concentration

One of the greatest challenges in the manufacturing and development of nanotechnologies is the requirement for robust, reliable, and accurate characterization data. Presented here are the results of an interlaboratory comparison (ILC) brought about through multiple rounds of engagement with NanoSight Malvern and ten pan-European research facilities. Following refinement of the nanoparticle tracking analysis (NTA) technique, the size and concentration characterization of nanoparticles in liquid suspension was proven to be robust and reproducible for multiple sample types in monomodal, binary, or multimodal mixtures. The limits of measurement were shown to exceed the 30–600 nm range (with all system models), with percentage coefficients of variation (% CV) being calculated as sub 5% for monodisperse samples. Particle size distributions were also improved through the incorporation of the finite track length adjustment (FTLA) algorithm, which most noticeably acts to improve the resolution of multimodal sample mixtures. The addition of a software correction to account for variations between instruments also dramatically increased the accuracy and reproducibility of concentration measurements. When combined, the advances brought about during the interlaboratory comparisons allow for the simultaneous determination of accurate and precise nanoparticle sizing and concentration data in one measurement.

Locating bomb factories by detecting hydrogen peroxide

The analytical capability to detect hydrogen peroxide vapour can play a key role in localizing a site where a H2O2 based Improvised Explosive (IE) is manufactured. In security activities it is very important to obtain information in a short time. For this reason, an analytical method to be used in security activity needs portable devices. The authors have developed the first analytical method based on a portable luminometer, specifically designed and validated to locate IE manufacturing sites using quantitative on-site vapour analysis for H2O2. The method was tested both indoor and outdoor. The results demonstrate that the detection of H2O2 vapours could allow police forces to locate the site, while terrorists are preparing an attack. The collected data are also very important in developing new sensors, able to give an early alarm if located at a proper distance from a site where an H2O2 based IE is prepared.

Emission of Carbon Nanofiber (CNF) from CNF-Containing Composite Adsorbents

Carbon nanofibers (CNFs) are a new class of synthesized carbonaceous materials receiving increased attention. They have been extensively studied due to their interesting properties (i.e., purity, mechanical strength, high geometric surface area) and potential for use as adsorbents and catalyst supports.(1–4) Production costs are significantly lower than those of carbon nanotubes (CNT), and CNFs provide high performance for certain applications.(5,6) CNFs are produced from chemical vapor deposition (CVD), the catalytic decomposition of hydrocarbon gases or carbon monoxide over selected metal particles, including iron, cobalt, nickel, and some of their alloys at temperatures in the range of 400–1000◦C.(5) CNFs are characterized by the graphite-like structure at the nanoscale. Variable alignments of laminated hexagonal layers along the fiber axis typically provide three types of CNFs: (1) platelet (aligned perpendicular to the fiber axis), (2) tubular (aligned parallel to the fiber axis), and (3) herringbone (aligned at an angle to the fiber axis).(2) These structures differ according to the growing conditions and the metal used as a catalyst.(7) Several studies have shown that CNFs improved adsorbent properties. For example, Lim et al.(3) gave activated carbon fiber (ACF) multiple additional properties by growing CNFs on its catalytic surface. This improved the performance of ACFs for such applications as SOx and NOx removal. Schlogl et al.(8) grew carbon nanostructures (CNFs and CNTs) on a carbonaceous carrier (activated carbon-AC) for the removal of metal species in water purification. In a recent study by some of the present study’s authors,(9) a composite of AC and CNFs (AC/CNF) was prepared. AC was impregnated with a nickel nitrate catalyst, and CNFs with a diameter between 10 to 20 mm were deposited on the catalyst particles in AC micropores using CVD. Prepared samples were then activated by CO2 to recover the surface area and micropores. The prepared composite adsorbent was tested for VOC adsorption and then employed in an organic vapor respirator cartridge in granular form. The breakthrough time of cyclohexane vapor for a cartridge prepared with CO2-activated AC/CNF was significantly longer than for those cartridges prepared with the original AC with the same weight of adsorbents. This study(9) suggested that the granular form of AC/CNF composite could be an efficient alternative adsorbent for respirator cartridges due to its larger adsorption capacities and lower weight. The broad utility of manufactured nanomaterials resulted in increased levels of production, greater risk of human exposure, and the potential for release of these novel materials into the environment. Therefore, close attention to potential health risks, i.e., the potential for exposure and toxic responses to manufactured nanoparticles, including various fibrous nanomaterials, is important.(10) A growing body of literature indicates a potential hazard from exposure to CNFs.(5,11–13) One study showed that CNFs can penetrate human cells in target organs and cause cellular damage.(12) Kisin

0072 Oil mist, from exposure determinants to early effect markers: an integrative study design

The present project focuses on the effects of occupational exposure to oil mists on a panel of exposure and effect biomarkers in an epidemiological study. The assumption is that different health outcomes are caused by reactive particles causing oxidative stress leading to lung inflammation and ultimately cancer or asthma. Ninety workers from France and Switzerland (30 controls, 30 exposed to straight cutting oil and 30 to soluble cutting oil) will be followed over two days after a non-exposed period of at least two days. The exposure assessment is based on measurements of particles, metals, aldehydes, amines, the intrinsic oxidative potential of aerosols and the cutting oil. Furthermore, exposure biomarkers are measured in exhaled breath condensate (EBC)- metals, ions (nitrite, nitrate...) and urine –metals, metabolites of PAHs- . Finally, exposure determinants will be collected to guide future efforts in exposure prevention. Effect biomarkers of oxidative stress (malondialdéhyde, 8-isoprostane, 8-hydroxy-2’-deoxyguanosine) in EBC and urine will be repeatedly measured as well as exhaled nitric oxide (FeNO), an inflammation marker. Genotoxic effects will be assessed using the buccal micronucleus cytome assay. Finally, the possible chronic effects of oil mist exposure on respiratory health will be explored by standard questionnaires. This integrative project will gain insights in the exposure determinants that drive the physiopathological effects, thus allowing an efficient prevention strategy to be developed.