Sampling strategies and analytical techniques for assessment of airborne micro and nano plastics.

The atmosphere is pervasively polluted by microplastics and nano plastics (M/NPs) released into indoor and outdoor areas. However, various methodologies and their limitations along with non-standardization make the comparison of information concerning their prevalence difficult. Such diversity in techniques greatly limits the interpretation of results. Herein, We extracted data from publications on PubMed and Embase database up to the year 2022 regarding sampling strategies, identification methods, and reporting data for M/NPs quantification. In this review, 5 major areas for measuring airborne M/NPs have been identified including pre-sampling/ sampling/ post-sampling/ analysis/ and contamination avoidance. There are many challenges specific to each of those sections that need to be resolved through further method development and harmonization. This review mainly focuses on the different methods for collecting atmospheric M/NPs and also the analytical tools which have been used for their identification. While passive sampling is the most user-friendly method, the most precise and reproducible approach for collecting plastic particles is an active method which is directly followed by visual counting as the most common physical analysis technique. Polymers collected using visual sorting are most frequently identified by spectroscopy (FTIR; Raman). However, destructive analytical techniques (thermal degradation) also provide precise chemical information. In all cases, the methods were screened for advantages, limitations, and fieldwork abilities. This review outlines and critiques knowledge gaps, and recommendations to support standardized and comparable future research.

Assessment of Experimental Techniques That Facilitate Human Granuloma Formation in an In Vitro System: A Systematic Review.

The process of granuloma formation is complex, and due to species differences, the validity of animal studies is somewhat questioned. Moreover, the large number of animals needed to observe the different stages of development also raises ethical questions. Therefore, researchers have explored the use of human peripheral blood mononuclear cells (PBMCs), a heterogeneous population of immune cells, in an in vitro model. This review included in vitro studies that focused on exposing PBMCs-from healthy, sensitized, or diseased individuals-to antigens derived from infectious agents-such as mycobacteria or Schistosoma spp.-or inorganic antigens-such as beryllium. The reviewed studies mainly explored how human in vitro granuloma models can contribute towards understanding the pathogenesis of granulomatous diseases, especially during the early stages of granuloma formation. The feasibility of granuloma modelling was thus largely assessed via experimental techniques including (1) granuloma scoring indices (GI), (2) cell surface markers and (3) cytokine secretion profiling. While granuloma scoring showed some similarities between studies, a large variability of culture conditions and endpoints measured have been identified. The lack of any standardization currently impedes the success of a human in vitro granuloma model.

Synthesis, characterization and toxicity assessment of a new polymeric nanoparticle, l-glutamic acid-g-p(HEMA).

The toxic effects of poly(HEMA)-based polymeric nanoparticles must be analyzed before their biomedical applications as drug delivery systems. The aim of the study was to characterize and evaluate the toxicity for its biocompatibility of a newly synthesized l-glutamic acid-g-p(HEMA) polymeric nanoparticle The nanoparticle was synthesized with surfactant-free emulsion polymerization and grafting techniques. Grafting efficiency was estimated at 58%. The nanoparticle shape was verified as nearly spherical by scanning electron microscopy. Atomic force microscopy images showed a rough surface topography. The nanoparticle had an average size of ~194.6 nm on zeta analysis, and the zeta potential value was -18 mV. Fourier transformed infrared spectroscopy revealed spectra from 750 to 4000 cm-1 and characteristic peaks of stretching bands. The swelling ratio was 46%. With 24-h exposure, p(HEMA) and l-glutamic acid-g-p(HEMA) did not have cytotoxic effects on a human bronchial epithelial cell line (16HBE) and human monocyte cell line by water-soluble tetrazolium salt 1 (WST-1) assay and lactate dehydrogenase assay (LDH). It did not show genotoxic potential by comet assay and did not have mutagenic effects on Salmonella typhimurium TA98, TA100, TA1535 and TA1537 strains by Ames test. The nanoparticle at 160 µg/ml showed 2% hemolytic activity on erythrocytes. On cell migration assay, the percentage closure difference between exposed and control cells was estimated at 21%. We found no irritation effect on Hen's egg test-chorioallantoic membrane test. We determined that the polymeric nanoparticle l-glutamic acid-g-p(HEMA) was biocompatible and has potential for use in a drug delivery system.

Development of a physiologically based kinetic model for 99m-technetium-labelled carbon nanoparticles inhaled by humans.

Particulate air pollution is associated with respiratory and cardiovascular morbidity and mortality. Recent studies investigated whether and to which extent inhaled ultrafine particles are able to translocate into the bloodstream in humans. However, their conclusions were conflicting. We developed a physiologically based kinetic model for (99m)technetium-labelled carbon nanoparticles (Technegas). The model was designed to analyse imaging data. It includes different translocation rates and kinetics for free technetium, and small and large technetium-labelled particles. It was calibrated with data from an experiment designed to assess the fate of nanoparticles in humans after inhalation of Technegas. The data provided time courses of radioactivity in the liver, stomach, urine, and blood. Parameter estimation was performed in a Bayesian context with Markov chain Monte Carlo (MCMC) techniques. Our analysis points to a likely translocation of particle-bound technetium from lung to blood, at a rate about twofold lower than the transfer rate of free technetium. Notably, restricting the model so that only free technetium would have been able to reach blood circulation resulted in much poorer fits to the experimental data. The percentage of small particles able to translocate was estimated at 12.7% of total particles. The percentage of unbound technetium was estimated at 6.7% of total technetium. To our knowledge, our model is the first PBPK model able to use imaging data to describe the absorption and distribution of nanoparticles. We believe that our modeling approach using Bayesian and MCMC techniques provides a reasonable description on which to base further model refinement.

Assessment of the sensitization potential of persulfate salts used for bleaching hair.

BACKGROUND: Persulfate salts have been associated with both allergic contact dermatitis and bronchial asthma. Because there is currently no experimental data available on the sensitizing properties of persulfate salts (ammonium, sodium, and potassium persulfates), we determined their dermal sensitizing capacity, using the murine local lymph node assay (LLNA). MATERIAL AND METHODS: For three consecutive days, BALB/c mice were dermally treated with ammonium, sodium, or potassium persulfate or with the vehicle alone (dimethyl sulfoxide) on each ear (2 x 25 microl). On D6, mice were injected intravenously with [(3)H]-methyl thymidine. The draining auricular lymph nodes were removed, and the incorporation of [(3)H]-methyl thymidine was compared with that of vehicle-treated control mice. A stimulation index (SI) relative to the vehicle-treated control value was derived. The sensitizing potency of the chemicals tested was determined by estimating the concentration of chemical required to induce a SI of 3 (EC3). RESULTS: All three chemicals provoked positive responses in the LLNA, with dose-dependent increases in proliferation. Maximal SIs recorded were 6.8 +/- 1.8, 6.5 +/- 1.2, and 5 +/- 1.0 at 5% for ammonium, sodium or potassium persulfate, respectively. The EC3 values were 1.9%, 0.9%, and 2.4% for ammonium, sodium, and potassium persulfates, respectively. CONCLUSIONS: All three persulfate salts need to be considered strong-to-moderate sensitizers according to the murine LLNA.

In vitro toxicity assessment of polyvinyl chloride particles and comparison of six cellular systems.

Occupational exposure to polyvinyl chloride (PVC) dust has been occasionally associated with lung disease. Our aim was to evaluate the in vitro toxicity of various types of PVC particles in relevant cell culture systems. Six samples from the normal industrial suspension process (PVC-S) and eight samples from the emulsion process (PVC-E) were studied. Cytotoxicity was assessed, using the MTT assay, after 20 h of incubation in A549 cells and in primary cultures of alveolar macrophages (AM) and type II pneumocytes (TII) obtained from rats (r-AM, r-TII) or from human surgical specimens (h-AM, h-TII). Hemolysis was assessed after 2 h of incubation with human erythrocytes (h-RBC). A positive control (crystalline SiO(2), Min-U-Sil) and relevant additives of these PVC particles were tested concurrently. No toxicity of PVC-S particles could be established up to 5 mg/ml in the hemolysis test and 2.5 mg/ml in the MTT assay. In contrast, 4 out of 8 PVC-E particles induced significant toxicity, with EC50 values ranging from 0.7 to 3.7 mg/ml in the hemolysis test and from 0.2 to 1.2 mg/ml in primary cells. The most toxic particles were those that contained the additives with the highest in vitro cytotoxicity. There was a good correlation between EC50 values obtained in relevant bioassays. The sensitivity order of the cell systems was A549 < h-RBC approximately h-TII < or = h-AM < r-TII < or = r-AM for the particles. In conclusion, PVC-E particles produced a moderate in vitro toxicity for primary rat and human pulmonary cells, probably because of the residual presence of additives.