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TECHNICAL CHALLENGES ASSOCIATED WITH ASSESSING THE IN VITRO PULMONARY TOXICITY OF CARBON NANOTUBES
Citation:
SNYDER, R. J., R. M. ZUCKER, R. H. JASKOT, AND K. L. DREHER. TECHNICAL CHALLENGES ASSOCIATED WITH ASSESSING THE IN VITRO PULMONARY TOXICITY OF CARBON NANOTUBES. Presented at Society of Toxicology Annual Meeting, Seattle, WA, March 16 - 20, 2008.
Impact/Purpose:
This study presents the challenges and results associated with assessing the effects which purified single-wall carbon nanotubes (SWCNT), produced by various methods, have on the cell growth/viability of the human airway BEAS 2B cell line.
Description:
Nanotechnology continues to produce a large number of diverse engineered nanomaterials (NMs) with novel physicochemical properties for a variety of applications. Test methods that accurately assess/predict the toxicity of NMs are critically needed and it is unclear whether current test methods are adequate. This study presents the challenges and results associated with assessing the effects which purified single-wall carbon nanotubes (SWCNT), produced by various methods, have on the cell growth/viability of the human airway BEAS 2B cell line. Residual oil fly ash (ROFA) was employed as a positive control in this study. SWCNTs were optimally dispersed in suspension by sonicating in 10% serum in tissue culture medium. BEAS 2B cells were exposed to various particle concentrations (5 to 200 μg/ml) and cellular toxicity assessed by multiple colorimetric assays (WST-1, MTT, and LDH release) and direct counting methods (hemacytometer/trypan blue staining and flow cytometry/calcien AM and propidium iodine staining). ROFA exposure produced a dose dependent increase in BEAS 2B cellular cytotoxicity detected with comparable results by all colorimetric assays and direct cell counting methods. MTT and WST-1 colorimetric assays were found to produce significantly different results following exposure of BEAS 2B cells to all SWCNTs. Direct cell counting methods had to be employed to accurately assess the effect which various SWCNTs had on BEAS 2B cell growth\viability. Results from hemacytometer cell counting and LDH analyses showed a differential ability of SWCNTs to inhibit BEAS 2B cellular growth with no effect on viability or cytotoxicity. These results were confirmed by flow cytometry analyses. These studies show the ability of SWCNTs to inhibit BEAS 2B cellular growth was dependent on their production method. In addition, certain colorimetric assays cannot accurately assess the cellular effects of SWCNTs. Finally, SWCNTs may alter airway cell growth by mechanisms different from environmental combustion particles. (This abstract does not necessarily reflect EPA Policy)