Development of a non-target strategy for evaluation of potential biological effects of inhalable aerosols generated during purposeful room conditioning using an in vitro inhalation model

Abstract

Objectives: An integrated in vitro inhalation approach was outlined to estimate potential adverse acute inhalation effects of aerosols from commercial nebulizer applications used for purposeful room conditioning such as disinfection, scenting or others. Aerosol characterization, exposure estimation and evaluation of acute biological effects by in vitro inhalation were included to generate dose-response data, allowing for determination of in vitro lowest observable adverse effect levels (LOAELs). Correlation of these to estimates of human lung deposition was included for quantitative in vitro to in vivo extrapolation approach (QIVIVE) for acute effects during human exposure.

Methods: To test the proposed approach, a case study was undertaken using two realistic test materials. An acute in vitro inhalation setup with air-liquid interface A549-cells in an optimized exposure situation (P.R.I.T.^® ExpoCube^®) was used to expose cells and analysis of relevant biological effects (viability, mitochondrial membrane potential, stress, IL-8 release) was carried out. Results: The observed dose-responsive effects in a sub-toxic dose-range could be attributed to the main component of one test material and its presence in the aerosol phase of the nebulized material. QIVIVE resulted in a factor of at least 256 between the in vitro LOAEL and the estimated acute human lung exposure for this test material.

Conclusions: The case-study shows the value of the non-target in vitro inhalation testing approach especially in case of a lack of knowledge on complex product composition. It is expected that approaches like this will be of high value for product safety and environmental health in the future.

HIGHLIGHTS

• Design of a routine in vitro inhalation approach to estimate biological effects of nebulized products.

• Application in a case study on a potential real product for purposeful room conditioning by use of a commercial nebulizer.

• Combining results from aerosol characterization and in vitro inhalation experiments allowed for comprehensive correlation of product composition, aerosol properties and biological effects.

• Assignment of sub-toxic biological effects to a specific product component enabled identification of a product composition with potentially even less biological effect.

• Combined in vivo exposure estimation and in vitro LOAEL determination enabled a QIVIVE approach.

Keywords:

• Inhalation
• in vitro
• acute toxicity
• non-target
• aerosol

Acknowledgements

The authors thank Nico Sonnenschein for conducting interleukin-8 ELISA assays and laboratory work referring to cellular read-outs, Martin Engelke for carrying out the A549 cell culture, Martin Stempfle for doing parts of the aerosol characterization work, Andreas Hiemisch for carrying out cell exposure, FT-IR analysis and general aerosol characterization as well as high content screening application and lab organization. Furthermore, the authors thank Prof. Dr. Wolfgang Koch for facilitating calculations of equilibrium aerosol concentrations and valuable discussions on the respective aspects of the study.

Disclosure statement

Rolf Fautz, Anne Zifle and Anne Fuchs are employees of a company selling cosmetic products, and providing the test items which are reported in the publication. All other authors are employees of the Fraunhofer Gesellschaft who is patentee of the ExpoCube^® technology (DE 10 2013 109 450).

Data availability statement

The data that support the findings of this study are available from the corresponding author, Detlef Ritter, upon reasonable request.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.