In Vitro Aerosol Exposure to Nanomaterials: From Laboratory to Environmental Field Toxicity Testing

Abstract

Exposure to nanomaterials (NMs) is inevitable, requiring robust toxicological assessment to understand potential environmental and human health effects. NMs are favored in many applications because of their small size; however, this allows them to easily aerosolize and, subsequently, expose humans via inhalation. Toxicological assessment of NMs by conventional methods in submerged cell culture is not a relevant way to assess inhalation toxicity of NMs because of particle interference with bioassays and changes in particokinetics when dispersed in medium. Therefore, an in vitro aerosol exposure chamber (AEC) was custom designed and used for direct deposition of NMs from aerosols in the environment to the air−liquid interface of lung cells. Human epithelial lung cell line, A549, was used to assess the toxicity of copper, nickel, and zinc oxide nanopowders aerosolized by acoustic agitation in laboratory study. Post optimization, the AEC was used in the field to expose the A549 cells to NM aerosols generated from firing a hand gun and rifle. Toxicity was assessed using nondestructive assays for cell viability and inflammatory response, comparing the biologic effect to the delivered mass dose measured by inductively coupled plasmamass spectrometry. The nanopowder exposure to submerged and ALI cells resulted in dose-dependent toxicity. In the field, weapon exhaust from the M4 reduced cell viability greater than the M9, while the M9 stimulated inflammatory cytokine release of IL-8. This study highlights the use of a portable chamber with the capability to assess toxicity of NM aerosols exposed to air− liquid interface in vitro lung cell culture.

Invited review: human air-liquid-interface organotypic airway tissue models derived from primary tracheobronchial epithelial cells—overview and perspectives

“…Exposing NP aerosols at the air interface could circumvent many of these issues and, overall, better represents how pulmonary NP exposures occur in vivo. Several studies have compared cellular responses between submerged and air-interface conditions (Raemy et al 2012;Tilly et al 2020). The deposited doses per surface area were first calculated for the respective studies to ensure that the comparison was made at equivalent doses.…”

“…For submerged cultures, deposited doses can be estimated based on the administered concentrations, particle characteristics, and particokinetics (Deloid et al 2014). For NP aerosol exposure, surface doses can be directly measured using QCM or atomic absorption spectroscopy (Raemy et al 2012;Tilly et al 2020). Differences were noted in dose-and time-response patterns and lowest-observed-adverse-effect levels.…”

New Approach Methods to Evaluate Health Risks of Air Pollutants: Critical Design Considerations for In Vitro Exposure Testing

“…Similar to the CCES, the Fraunhofer Institute developed the ExpoCube system that also incorporates thermophoresis-enhanced particle deposition, where a 12-well tissue culture plate can be placed inside the system [101]. Other perpendicular flow systems focused on portability for on-site field testing have also been developed [102,103].…”

Characterization of toxicological effects of complex nano‐sized metal particles using in vitro human cell and whole blood model systems

“…Characterization of the multiple toxicological effects caused by human exposure to complex nano-sized metal particles can be problematic, but tests performed on cultured epithelial and endothelial cells in vitro facilitate such investigations (Ahlinder et al, 2013;Lai et al, 2016;Tilly et al, 2020). Recently, a method based on an ex vivo model of human blood enabled examinations of particle-induced procoagulatory factors and mediators of vascular inflammation (Ekdahl et al, 2018;Ekstrand-Hammarström et al, 2015).…”

“…Increased reports of symptoms appear concomitant with the introduction of lead (Pb)-free ammunition, a substitution implemented primarily to protect the environment. Moreover, the amount of evidence demonstrating that ultrafine particle emissions of fine-caliber Pb-free ammunition comprising numerous metals present both a cytotoxic and immunogenic risk is also increasing (Bergström et al, 2015;Mariussen et al, 2021;Tilly et al, 2020;Wingfors et al, 2014). However, because Pb exposure constitutes a health risk for police officers, Pb-free primer and bullet alternatives are still promoted for regular shooting exercises (Laidlaw et al, 2017).…”