First order risk assessment for nanoparticle inhalation exposure during injection molding of polypropylene composites and production of tungsten-carbide-cobalt fine powder based upon pulmonary inflammation and surface area dose

AbstractInhalation exposure to low toxicity and biodurable particles has shown to induce polymorphonuclear neutrophilia (PMN) in the lungs, which is a strong indicator for lung inflammation. Recently, Schmid and Stoeger (2016; http://dx.doi.org/10.1016/j.jaerosci.2015.12.006) reviewed mice and rat intratracheal instillation studies and assessed the relation between particles dry powder BET surface area dose and PMN influx for granular biodurable particles (GBPs) and transition metal oxides. In this study, we measured workers alveolar lung deposited surface area (LDSA) concentrations (μm2 cm−3) during injection molding of polypropylene (PP) car bumpers and production of tungsten-carbide-cobalt (WCCo) fine grade powder using diffusion chargers. First order risk assessment was performed by comparing the doses calculated from measured LDSA concentrations during an 8-h work day with the NOEL1/100, the one hundredth of no observed effect level, assigned for GBPs (0.11cm2g−1) and transition metal oxide particles (9×10−3cm2g−1). During the injection molding of PP car bumpers, LDSA concentrations varied from 23 to 39.8μm2cm−3. During 8-h exposure PP, particle doses were at a maximum of 1.4×10−3cm2g−1, which was a factor 100 lower compared to the NOEL1/100 assigned for GBPs. In the WCCo fine powder production plant, the LDSA concentrations were below 18.7μm2cm−3, which corresponds to the 8-h dose of 2.7×10−3cm2g−1. This is 3 times lower than the NOEL1/100 assigned for transition metal oxide particles. The LDSA concentrations were generally low compared to urban background levels of 44.2μm2cm−3 in European cities

First order risk assessment for nanoparticle inhalation exposure during injection molding of polypropylene composites and production of tungsten-carbide-cobalt fine powder based upon pulmonary inflammation and surface area dose

AbstractInhalation exposure to low toxicity and biodurable particles has shown to induce polymorphonuclear neutrophilia (PMN) in the lungs, which is a strong indicator for lung inflammation. Recently, Schmid and Stoeger (2016; http://dx.doi.org/10.1016/j.jaerosci.2015.12.006) reviewed mice and rat intratracheal instillation studies and assessed the relation between particles dry powder BET surface area dose and PMN influx for granular biodurable particles (GBPs) and transition metal oxides. In this study, we measured workers alveolar lung deposited surface area (LDSA) concentrations (μm2 cm−3) during injection molding of polypropylene (PP) car bumpers and production of tungsten-carbide-cobalt (WCCo) fine grade powder using diffusion chargers. First order risk assessment was performed by comparing the doses calculated from measured LDSA concentrations during an 8-h work day with the NOEL1/100, the one hundredth of no observed effect level, assigned for GBPs (0.11cm2g−1) and transition metal oxide particles (9×10−3cm2g−1). During the injection molding of PP car bumpers, LDSA concentrations varied from 23 to 39.8μm2cm−3. During 8-h exposure PP, particle doses were at a maximum of 1.4×10−3cm2g−1, which was a factor 100 lower compared to the NOEL1/100 assigned for GBPs. In the WCCo fine powder production plant, the LDSA concentrations were below 18.7μm2cm−3, which corresponds to the 8-h dose of 2.7×10−3cm2g−1. This is 3 times lower than the NOEL1/100 assigned for transition metal oxide particles. The LDSA concentrations were generally low compared to urban background levels of 44.2μm2cm−3 in European cities

Particle emission rates during electrostatic spray deposition of TiO2 nanoparticle-based photoactive coating

A new method for the covalent and specific labeling of fusion proteins of carrier proteins (CPs) with small organic molecules has been developed in this work. This technology combines the convenience of expressing genetically tagged reporter proteins with the versatility of synthetic organic molecules. Moreover it promises to overcome some of the limitations of the currently used approaches. The method is based on the posttranslational modification of CPs by phosphopantetheine transferase (PPTase). In this reaction, the 4'-phosphopantetheine group of coenzyme A (CoA) is transferred to a serine residue of CP by PPTase. The PPTase can also use as substrates CoA derivatives that are modified in the thiol moiety by fluorophores or affinity reporter groups that are transferred to CP by PPTase in a covalent and irreversible manner. In this work, several CoA derivatives were synthesized by coupling of CoA with reporter groups functionalized by maleimide. The labeling method using the acyl carrier protein (ACP) and the PPTase (AcpS) from E. coli was applied to the in vitro labeling of purified proteins or in E. coli and yeast lysates, but also to the labeling of proteins expressed on cell surfaces of yeast and mammalian cells. The labeling reaction is fast, specific and quantitative. Pulse-chase labeling experiments with different fluorophores allowed the visualization of different protein generations on yeast cell surfaces. Thus, the method was demonstrated to be attractive for fluorescence microscopy. The second objective was to create a system for the selective labeling of different CPs with different CoA derivatives in the same sample, which requires PPTases with different specificities. The labeling must be performed sequentially, in order that each CP is labeled with only one CoA derivative. The pair peptidyl carrier protein (PCP) from B. brevis and the PPTase from B. subtilis (Sfp) was chosen as counterpart of the pair ACP / AcpS from E. coli. AcpS that is specific towards ACP is used for the first labeling reaction, and after a washing step to remove excess of substrate, the second labeling is performed with Sfp which is promiscuous. The system was successfully tested in vitro in solution and with proteins immobilized on microarrays, and on the surface of yeast and mammalian cells. Finally, the last objective was to reduce the size of the carrier protein (∼ 80 amino acids) to a minimal motif that is efficiently recognized by the PPTase. ACP and PCP were truncated before and after helix II whose residues are involved in the recognition by AcpS and Sfp. The fragments of ACP (aa 27-50) and PCP (aa 37-59) were labeled by AcpS and Sfp respectively, but the kinetics of labeling was slow. Two libraries were created with randomization of the six amino acids around the modified serine. Selections were performed using a phage display system based on the phagemid technology. Mt1 (32 aa) was modified by AcpS at the same rate as wild type ACP. Additional truncations of mt1 sequence yielded mt1.4 (16 aa) that was efficiently recognized by AcpS and weakly by Sfp. In conclusion, this labeling method should become an important tool for studies of cell surface proteins as well as for in vitro applications

No Cytotoxicity or Genotoxicity of Graphene and Graphene Oxide in Murine Lung Epithelial FE1 Cells in Vitro

International audienceGraphene and graphene oxide receive much attention these years, because they add attractive properties to a wide range of applications and products. Several studies have shown toxicological effects of other carbon-based nanomaterials such as carbon black nanoparticles and carbon nanotubes in vitro and in vivo. Here, we report in-depth physicochemical characterization of three commercial graphene materials, one graphene oxide (GO) and two reduced graphene oxides (rGO) and assess cytotoxicity and genotoxicity in the murine lung epithelial cell line FE1. The studied GO and rGO mainly consisted of 2-3 graphene layers with lateral sizes of 1-2 mu m. GO had almost equimolar content of C, O, and H while the two rGO materials had lower contents of oxygen with C/O and C/H ratios of 8 and 12.8, respectively. All materials had low levels of endotoxin and low levels of inorganic impurities, which were mainly sulphur, manganese, and silicon. GO generated more ROS than the two rGO materials, but none of the graphene materials influenced cytotoxicity in terms of cell viability and cell proliferation after 24 hr. Furthermore, no genotoxicity was observed using the alkaline comet assay following 3 or 24 hr of exposure. We demonstrate that chemically pure, few-layered GO and rGO with comparable lateral size (> 1 mu m) do not induce significant cytotoxicity or genotoxicity in FE1 cells at relatively high doses (5-200 mu g/ml). Environ. Mol. Mutagen. 57:469-482, 2016. (c) 2016 The Authors. Environmental and Molecular Mutagenesis Published by Wiley Periodicals, Inc