Effects of Laser Printer–Emitted Engineered Nanoparticles on Cytotoxicity, Chemokine Expression, Reactive Oxygen Species, DNA Methylation, and DNA Damage: A Comprehensive in Vitro Analysis in Human Small Airway Epithelial Cells, Macrophages, and Lymphoblasts

Abstract

BackgroundEngineered nanomaterials (ENMs) incorporated into toner formulations of printing equipment become airborne during consumer use. Although information on the complex physicochemical and toxicological properties of both toner powders and printer-emitted particles (PEPs) continues to grow, most toxicological studies have not used the actual PEPs but rather have primarily used raw toner powders, which are not representative of current exposures experienced at the consumer level during printing.ObjectivesWe assessed the biological responses of a panel of human cell lines to PEPs.MethodsThree physiologically relevant cell lines—small airway epithelial cells (SAECs), macrophages (THP-1 cells), and lymphoblasts (TK6 cells)—were exposed to PEPs at a wide range of doses (0.5–100 μg/mL) corresponding to human inhalation exposure durations at the consumer level of 8 hr or more. Following treatment, toxicological parameters reflecting distinct mechanisms were evaluated.ResultsPEPs caused significant membrane integrity damage, an increase in reactive oxygen species (ROS) production, and an increase in pro-inflammatory cytokine release in different cell lines at doses equivalent to exposure durations from 7.8 to 1,500 hr. Furthermore, there were differences in methylation patterns that, although not statistically significant, demonstrate the potential effects of PEPs on the overall epigenome following exposure.ConclusionsThe in vitro findings obtained in this study suggest that laser printer–emitted engineered nanoparticles may be deleterious to lung cells and provide preliminary evidence of epigenetic modifications that might translate to pulmonary disorders.CitationPirela SV, Miousse IR, Lu X, Castranova V, Thomas T, Qian Y, Bello D, Kobzik L, Koturbash I, Demokritou P. 2016. Effects of laser printer–emitted engineered nanoparticles on cytotoxicity, chemokine expression, reactive oxygen species, DNA methylation, and DNA damage: a comprehensive in vitro analysis in human small airway epithelial cells, macrophages, and lymphoblasts. Environ Health Perspect 124:210–219; http://dx.doi.org/10.1289/ehp.1409582

A critical review of in vitro dosimetry for engineered nanomaterials

“…Some groups have already reported that the time required to deliver ENMs to cells may be a rate-limiting factor in cellular internalization and translocation [60,96]. Better characterization of in vitro dose will also enable comparison of in vitro doseresponse outcomes with effective doses and measured biological response patterns in vivo [3,85]. Importantly, reducing uncertainty regarding reported effective dose values will enable consolidation of nano-biointeraction results from various labs and biological systems into large libraries of comprehensive toxicity characterization data such as 'ISA-TAB-Nano' [23,100].…”

“…In order to ensure accurate and meaningful comparisons between the results of in vitro and in vivo studies, upon which the utility of in vitro toxicity screening is entirely dependent, ENM concentrations in in vitro nanotoxicity studies must be carefully selected such that the effective doses match those employed in the corresponding in vivo studies [3,28,33,85]. Numerical models, such as the widely used and well-accepted multiplepath particle dosimetry model (MPPD) [86,87] have long been employed to estimate the delivered in vivo dose of inhaled particles.…”

Markers of lipid oxidative damage in the exhaled breath condensate of nano TiO2 production workers

“…Furthermore, TiO 2 is permitted for use as an additive (E171) in food. NanoTiO 2 is used in numerous applications, including coatings, antibacterial sprays, composite nanofillers, copy toners, printing inks, and cosmetics, as well as in the pharmaceutical industry (Khatri et al, 2013a;Pirela et al, 2016;Warheit, 2013;Weir et al, 2012). TiO 2 is a high-volume material, with nano-sized TiO 2 material being increasingly used in many applications.…”

Markers of oxidative damage of nucleic acids and proteins among workers exposed to TiO2(nano) particles

“…The toxic/genotoxic effects induced by reactive oxygen species (ROS) and reactive nitration species (RNS) can contribute to tumourigenesis in multiple ways, including through the formation of DNA adducts, nucleic acids and proteins’ oxidative products 4 5 6 7. The exact site of the DNA damage is unknown and further research is needed to elucidate the mechanisms for ROS formation and carcinogenesis 8.…”