In vitro toxicity of silica substitutes used for abrasive blasting

Vallyathan, Val; Blake, Terri; Leonard, Steve; Greskevitch, Mark; Jones, William G.; Pack, Donna; Schwegler‐Berry, Diane; Miller, William E.; Castranova, Vincent

doi:10.1002/(sici)1097-0274(199909)36:1+<158::aid-ajim56>3.0.co;2-r

Cited by 5 publications

(2 citation statements)

References 2 publications

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“…If the particle surface has transition metal present, such as Fe, then it may generate radicals through a Fenton-like reaction. Silica particles, chromium and welding fumes all generated free radical production under similar exposure conditions (Leonard et al, 2000, 2010; Vallyathan et al, 1999). In order for particles to generate free radicals in a cellular system, the cell must first recognize and react with the particles.…”

Section: Discussionmentioning

confidence: 92%

Lung biodurability and free radical production of cellulose nanomaterials

Stefaniak

Seehra

Fix

et al. 2014

Inhalation Toxicology

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The potential applications of cellulose nanomaterials in advanced composites and biomedicine makes it imperative to understand their pulmonary exposure to human health. Here, we report the results on the biodurability of three cellulose nanocrystal (CNC), two cellulose nanofibril (CNF) and a benchmark cellulose microcrystal (CMC) when exposed to artificial lung airway lining fluid (SUF, pH 7.3) for up to 7 days and alveolar macrophage phagolysosomal fluid (PSF, pH 4.5) for up to 9 months. X-ray diffraction analysis was used to monitor biodurability and thermogravimetry, surface area, hydrodynamic diameter, zeta potential and free radical generation capacity of the samples were determined (in vitro cell-free and RAW 264.7 cell line models). The CMC showed no measurable changes in crystallinity (xCR) or crystallite size D in either SUF or PSF. For one CNC, a slight decrease in xCR and D in SUF was observed. In acidic PSF, a slight increase in xCR with exposure time was observed, possibly due to dissolution of the amorphous component. In a cell-free reaction with H2O2, radicals were observed; the CNCs and a CNF generated significantly more ●OH radicals than the CMC (p<0.05). The ●OH radical production correlates with particle decomposition temperature and is explained by the higher surface area to volume ratio of the CNCs. Based on their biodurability, mechanical clearance would be the primary mechanism for lung clearance of cellulose materials. The production of ●OH radicals indicates the need for additional studies to characterize the potential inhalation hazards of cellulose.

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Section: Discussionmentioning

confidence: 92%

Lung biodurability and free radical production of cellulose nanomaterials

Stefaniak

Seehra

Fix

et al. 2014

Inhalation Toxicology

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“…Airborne emissions include particles of various sizes and particulate metals, such as arsenic, cadmium, chromium (trivalent and hexavalent), lead, manganese, nickel, titanium, and others. [5][6][7][8] A study conducted to assess the toxicity of spent abrasives showed that metal concentrations can exceed the Toxicity Characteristic Leaching Procedure criteria limits. 9 Particulate emissions are of great concern because of the potential health effects, visibility impairment, ecosystem imbalance, and esthetic damage.…”

Section: Introductionmentioning

confidence: 99%

Atmospheric Particulate Emissions from Dry Abrasive Blasting Using Coal Slag

Kura

Kambham

Sangameswaran

et al. 2006

Journal of the Air & Waste Management Association

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Coal slag is one of the widely used abrasives in dry abrasive blasting. Atmospheric emissions from this process include particulate matter (PM) and heavy metals, such as chromium, lead, manganese, nickel. Quantities and characteristics of PM emissions depend on abrasive characteristics and process parameters. Emission factors are key inputs to estimate emissions. Experiments were conducted to study the effect of blast pressure, abrasive feed rate, and initial surface contamination on total PM (TPM) emission factors for coal slag. Rusted and painted mild steel surfaces were used as base plates. Blasting was carried out in an enclosed chamber, and PM was collected from an exhaust duct using U.S. Environment Protection Agency source sampling methods for stationary sources. Results showed that there is significant effect of blast pressure, feed rate, and surface contamination on TPM emissions. Mathematical equations were developed to estimate emission factors in terms of mass of emissions per unit mass of abrasive used, as well as mass of emissions per unit of surface area cleaned. These equations will help industries in estimating PM emissions based on blast pressure and abrasive feed rate. In addition, emissions can be reduced by choosing optimum operating conditions.

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Abrasive Blasting Agents: Designing Studies to Evaluate Relative Risk

Hubbs

Greskevitch

Kuempel

et al. 2005

Journal of Toxicology and Environmental Health, Part A

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Workers exposed to respirable crystalline silica used in abrasive blasting are at increased risk of developing a debilitating and often fatal fibrotic lung disease called silicosis. The National Institute for Occupational Safety and Health (NIOSH) recommends that silica sand be prohibited as abrasive blasting material and that less hazardous materials be used in blasting operations. However, data are needed on the relative risks associated with exposure to abrasive blasting materials other than silica. NIOSH has completed acute studies in rats (Hubbs et al., 2001; Porter et al., 2002). To provide dose-response data applicable to making recommendation for occupational exposure limits, NIOSH has collaborated with the National Toxicology Program (NTP) to design longer term studies with silica substitutes. For risk assessment purposes, selected doses will include concentrations that are relevant to human exposures. Rat lung burdens achieved should be comparable to those estimated in humans with working lifetime exposures, even if this results in "overloading" doses in rats. To quantify both dose and response, retained particle burdens in the lungs and lung-associated lymph nodes will be measured, as well as biochemical and pathological indices of pulmonary response. This design will facilitate assessment of the pulmonary fibrogenic potential of inhaled abrasive blasting agents at occupationally relevant concentrations.

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In vitro toxicity of silica substitutes used for abrasive blasting

Cited by 5 publications

References 2 publications

Lung biodurability and free radical production of cellulose nanomaterials

Lung biodurability and free radical production of cellulose nanomaterials

Atmospheric Particulate Emissions from Dry Abrasive Blasting Using Coal Slag

Abrasive Blasting Agents: Designing Studies to Evaluate Relative Risk

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