Evaluation of sampling methods for toxicological testing of indoor air particulate matter

Abstract

There is a need for toxicity tests capable of recognizing indoor environments with compromised air quality, especially in the context of moisture damage. One of the key issues is sampling, which should both provide meaningful material for analyses and fulfill requirements imposed by practitioners using toxicity tests for health risk assessment. We aimed to evaluate different existing methods of sampling indoor particulate matter (PM) to develop a suitable sampling strategy for a toxicological assay. During three sampling campaigns in moisture-damaged and non-damaged school buildings, we evaluated one passive and three active sampling methods: the Settled Dust Box (SDB), the Button Aerosol Sampler, the Harvard Impactor and the National Institute for Occupational Safety and Health (NIOSH) Bioaerosol Cyclone Sampler. Mouse RAW264.7 macrophages were exposed to particle suspensions and cell metabolic activity (CMA), production of nitric oxide (NO) and tumor necrosis factor (TNFα) were determined after 24 h of exposure. The repeatability of the toxicological analyses was very good for all tested sampler types. Variability within the schools was found to be high especially between different classrooms in the moisture-damaged school. Passively collected settled dust and PM collected actively with the NIOSH Sampler (Stage 1) caused a clear response in exposed cells. The results suggested the higher relative immunotoxicological activity of dust from the moisture-damaged school. The NIOSH Sampler is a promising candidate for the collection of size-fractionated PM to be used in toxicity testing. The applicability of such sampling strategy in grading moisture damage severity in buildings needs to be developed further in a larger cohort of buildings.

Keywords:

• Indoor air
• in vitro
• moisture damage
• particulate matter
• sampling
• toxicity testing

Acknowledgements

The authors would like to thank Matti Peltonen and Katja Saarnio for technical assistance and the participating schools for their collaboration.

Declaration of interest

The findings and conclusions in this report are those of the authors and do not necessarily represent the views of the National Institute for Occupational Safety and Health.

Funding

This work was supported by Tekes – the Finnish Funding Agency for Innovation, New knowledge and business from research ideas – HOVAVART (Homevaurion vakavuuden arviointi toksisuustestin avulla) Grant agreement no. 2285733-9. Professor Maija-Riitta Hirvonen, Drs Martin Täubel and Kati Huttunen as well as doctoral students Jenni Tirkkonen and Hanna Leppänen reported funding from Tekes – the Finnish Funding Agency for Innovation, New knowledge and business from research ideas – HOVAVART (Homevaurion vakavuuden arviointi toksisuustestin avulla) Grant agreement no. 2285733-9. Dr Bean T Chen has U.S. Patent Nos. 8,205,511 & 7,370,543 issued. Drs Anne Hyvärinen and William G Lindsley reported no declarations of interest. Doctoral student Jenni Tirkkonen was also funded by The Finnish Work Environment Fund Grant agreement no. 115283.

Supplementary material available online