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Wood combustion and cytotoxicity

A current ‘hot topic’ in genetic toxicology is the impact of particulate matter on human health arising from the combustion of logs in domestic fires.

Particulate matter has been identified as a major environmental pollutant causing severe health problems. Large amounts of the harmful particulate matter are emitted from wood combustion in domestic fires, but the toxicological and genotoxicological properties of wood combustion particles are poorly known.

Researchers from the National Institute for Health and Welfare in Finland and their collaborators investigated the chemical and consequent toxicological characteristics of particulate matter emitted from different phases of batch combustion in four different heating appliances. During the experimentation, mouse macrophages and human bronchial epithelial cells were exposed for 24 hours to different doses (between 15–300 µg/mL) of wood combustion particles. After this exposure, cytotoxicity, genotoxicity, production of the inflammatory mediators and effects on the cell cycle were assessed. The researchers chose to use the comet assay to asses DNA damage. Three replicate experiments were conducted. The cells were analysed in ethidium bromide-stained slides using the Comet Assay IV image analysis system from Perceptive Instruments Ltd.

All the wood combustion samples exerted high cytotoxicity, but only moderate inflammatory activity. The particles emitted from the inefficient phase of batch combustion in one heating appliance, the sauna stove, induced the most extensive cytotoxic and genotoxic responses in mammalian cells. Polycyclic aromatic hydrocarbons and other organic compounds in particulate matter samples might have contributed to these effects. Instead, water-soluble metals seemed to participate in the cytotoxic responses triggered by the particles from more efficient batch combustion in the masonry heaters. Overall, the researchers demonstrated that the toxicological responses were decreased when the combustion phase was more efficient.

The researchers concluded that the efficiency of batch combustion plays a significant role in the harmfulness of particulate matter, even under incomplete wood combustion processes.

Case study based upon:
Efficiency of log wood combustion affects the toxicological and chemical properties of emission particles Tapanainen M, Jalava PI, Mäki-Paakkanen J, Hakulinen P, Lamberg H, Ruusunen J, Tissari J, Jokiniemi J, Hirvonen MR. Department of Environmental Health, National Institute for Health and Welfare, Kuopio, Finland. Inhal Toxicol. 2012 May;24(6):343-55.