Characterization and Cytotoxic Assessment of Ballistic Aerosol Particulates for Tungsten Alloy Penetrators into Steel Target Plates

Abstract

The nature and constituents of ballistic aerosol created by kinetic energy penetrator rods of tungsten heavy alloys (W-Fe-Ni and W-Fe-Co) perforating steel target plates was characterized by scanning and transmission electron microscopy. These aerosol regimes, which can occur in closed, armored military vehicle penetration, are of concern for potential health effects, especially as a consequence of being inhaled. In a controlled volume containing 10 equispaced steel target plates, particulates were systematically collected onto special filters. Filter collections were examined by scanning and transmission electron microscopy (SEM and TEM) which included energy-dispersive (X-ray) spectrometry (EDS). Dark-field TEM identified a significant nanoparticle concentration while EDS in the SEM identified the propensity of mass fraction particulates to consist of Fe and FeO, representing target erosion and formation of an accumulating debris field. Direct exposure of human epithelial cells (A549), a model for lung tissue, to particulates (especially nanoparticulates) collected on individual filters demonstrated induction of rapid and global cell death to the extent that production of inflammatory cytokines was entirely inhibited. These observations along with comparisons of a wide range of other nanoparticulate species exhibiting cell death in A549 culture may suggest severe human toxicity potential for inhaled ballistic aerosol, but the complexity of the aerosol (particulate) mix has not yet allowed any particular chemical composition to be identified.

Comparative microstructures and cytotoxicity assays for ballistic aerosols composed of micrometals and nanometals: respiratory health implications

“…There was no indication of elemental mixing of the target and tungsten heavy alloy (Fe and W, respectively). 6 Although the projectiles also contained about 8% (weight) of either Fe and Ni, or Fe and Co, there was no significant evidence of these elements either in combined (or alloyed) form or as single-component nanoparticulates in the collected aerosol, even though the nanoparticulate fraction collected on the filters dominated the particle concentration.…”

“…1,3,5 A recent study by Machado et al of filter collections representing aerosol debris resulting from heavy alloy tungsten, kinetic energy rod projectiles penetrating steel plate arrays in steel enclosures demonstrated the induction of rapid and complete death of a human epithelial cell type in culture. 6 This suggests that there may be a severe human toxicity potential for inhaled ballistic aerosol inside an armored vehicle penetrated by a variety of projectiles, particularly of tungsten heavy alloy rods into steel armor.…”

“…While Gold et al 8 and Machado et al 6 detected a variety of ultrafine (nanosized) and fine (micron-sized) particulates, only the work by Machado et al demonstrated severe respiratory health implications, although there was no clear indication of the specific role played by nanoparticulates in contrast with fine micron-sized particulates, or chemical speciation effects.…”

“…In addition, we performed energy-dispersive X-ray analysis and highresolution elemental mapping of previously collected aerosol particles scraped from collection filters in order to establish the elemental compositions (chemistries) for a wide distribution of collected particulates, particularly nanoparticulates, for comparison with the speciated particulates, by doing a comparison of the prior cell culture assay results 6 with those for speciated particulates. Finally, we mixed speciated nanoparticulates (Fe/W, W/Ni, W/Co Fe/Ni, Fe/Co) and examined their cytotoxicity in contrast with the original filter assays, as well as the single-element particulates in the context of symbiotic effects for mixed chemistries, especially for the collected nanoparticulates.…”

The Development of Magnetic Drug Delivery and Disposition

“…Regardless of the advantages for aerosol droplets with magnetic particles, the objective risk assessment studies have to be performed. Many of studies confirmed that the metal oxide particles are very toxic, especially in the pulmonary system (Machado et al, 2010). Nowadays, the in vitro studies are focused on the characterization and cytotoxic assessment of aerosol particulates, especially the nanoparticles based on heavy alloys W-FeNi and W-Fe-Co.…”