Range-Finding Risk Assessment of Inhalation Exposure to Nanodiamonds in a Laboratory Environment

Abstract

This study considers fundamental methods in occupational risk assessment of exposure to airborne engineered nanomaterials. We discuss characterization of particle emissions, exposure assessment, hazard assessment with in vitro studies, and risk range characterization using calculated inhaled doses and dose-response translated to humans from in vitro studies. Here, the methods were utilized to assess workers’ risk range of inhalation exposure to nanodiamonds (NDs) during handling and sieving of ND powder. NDs were agglomerated to over 500 nm particles, and mean exposure levels of different work tasks varied from 0.24 to 4.96 µg·m−3 (0.08 to 0.74 cm−3). In vitro-experiments suggested that ND exposure may cause a risk for activation of inflammatory cascade. However, risk range characterization based on in vitro dose-response was not performed because accurate assessment of delivered (settled) dose on the cells was not possible. Comparison of ND exposure with common pollutants revealed that ND exposure was below 5 μg·m−3, which is one of the proposed exposure limits for diesel particulate matter, and the workers’ calculated dose of NDs during the measurement day was 74 ng which corresponded to 0.02% of the modeled daily (24 h) dose of submicrometer urban air particles.

Comparison of Geometrical Layouts for a Multi-Box Aerosol Model from a Single-Chamber Dispersion Study

“…While the present study has shown, especially the two-and three-box layouts predicted well the concentration levels in a well-controlled environment, the next step is to test the model performance by comparing modelled exposure levels with measured exposure levels in different environments. A successful comparison requires exposure studies, where contextual information is described well, and that concentrations are measured from multiple locations (see, e.g., occupational exposure studies by Jensen et al [29], Koponen et al [42], Mølgaard et al [22], Koivisto et al [25,[43][44][45], and Fonseca et al [46,47]). In addition, chamber studies will be carried out to characterise the significance of source strength measurements and the dispersion factor.…”

Airborne engineered nanomaterials in the workplace—a review of release and worker exposure during nanomaterial production and handling processes

“…Collecting end-product materials from chemical synthesis [23]; batch collection by industrial cyclone [24]; emptying and tipping powder materials from bucket to bucket [25]; scooping spilt materials off a table [25]; opening a furnace and transferring materials to vials [6]; manually loading and unloading trays [6]; dumping materials into a mixing tank [6]; detaching and removing CNTs from growth substrate using a razor blade [26]; sieving powders with a vibratory sieve shaker [27,28] Physical & chemical synthesis Gas-phase production of metal-based nanoparticles [29]; flame spray pyrolysis technique (FSP) [30,31]; induced coupled plasma with electric atomizer [32,33]; reaction collection [23]; electric arc reaction [34]; hot-wall reaction [19]; combustion reaction [35]; chemical vapor deposition (CVD) [26,[36][37][38][39]; water-assisted CVD [40] Weighing & mixing…”

“…Spraying and filtration of CNT solutions [37]; spraying solution onto a bulk absorbent [6]; changing a spray dryer drum [6]; spraying a suspension [9]; flame-spraying for surface coating and modification [50]; sonicating materials with different surface coatings in a hood [6]; sonication in an unventilated enclosure [7]; pelletizing and bagging products in a warehouse [51]; purification and functionalization [47] integrating MWCNT powder in coatings, dispersions, and plastics [52] [53], Al2O3 [53], CeO2 [53], iron oxides [6], Mn [6], Ag [6,54], Co [6], Si [19]; Carbonaceous: carbon black [23], CNT [26], SWCNT [25,40,55], MWCNT [6,28,37,47], carbon nanofibers (CNFs) [6,48], carbon nanopearls [6], nano diamond [27], carbon nanodiscs/carbon nanocones [28], nanoscale graphene platelets [56].…”

Ultrafine and nanoparticle formation and emission mechanisms during laser processing of ceramic materials

“…Nanoparticle emissions from industrial processes are receiving increasing attention in the literature in recent years (Demou, Peter, & Hellweg, 2008;Pfefferkorn et al, 2010;Curwin & Bertke, 2011;Gandra, Miranda, Vilaça, Velhinho, & Teixeira, 2011;Koivisto et al, 2012;Van Broekhuizen, 2012;Gómez, Irusta, Balas, & Santamaria, 2013;Fonseca et al, 2014;Gomez et al, 2014;Voliotis et al, 2014;Koivisto et al, 2014). These works focus on different types of processes, and reveal that nanoparticle emissions and subsequent exposures may reach up to particle number concentrations of 1 Â 10 6 parts cm À 3 such as the cases of firing processes where the painting and glazing of ceramics occur (Voliotis et al, 2014), as well as during and welding/soldering (Gómez et al, 2013).…”