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Lung damage from agricultural fires probed
Organic compounds and particular matter released when burning forests to clear land for agriculture can kill human lung cells or lead to irreversible damage to DNA, according to a new study.
A controlled burn. 
Burning forest to make land suitable for farming or to rear livestock is a widespread practice in many parts of the developing world. Nearly three billion people around the world are exposed to contaminants from biomass burning as a result of farming practices, deforestation, and burning wood or charcoal for fuel.
A team of Brazilian researchers studied particles released during the burning of biomass using material they collected in the Amazon forest, to assess how inhaling them can impact on human health.
To do this, they exposed human lung tissue to particulate matter smaller than 10 microns (10 μm), which is commonly emitted as a result of these fires and can reach the lung alveoli.
A high amount of pro-inflammatory molecules were produced by the cells almost as soon as exposure began. The cells also started to release significance amounts of Reactive Oxygen Species (ROS), a type of substance that damages cellular structures when produced in high quantities.
The cells then stopped multiplying, and this suggests damage in the DNA.
The first signs of damage were observed just 24 hours after of exposure. As time passed, the genetic damage increased, and cells underwent apoptosis [non-inflammatory cell death] and necrosis [cell death that leads to inflammation]”.
Three days later, 33 per cent of the exposed cells had died by necrosis, compared with 2 per cent of cells without exposure. The surviving cells also showed signs of DNA damage which means they can be predisposed to developing cancer in the future.
During their analysis of compounds released from the substances picked up in the Amazon, the researchers became aware of the presence of a range of polycyclic aromatic hydrocarbons (HAPs), which are typically released as a result of burning organic materials, including cooked steak. Many HAPs are already recognised as carcinogenic, however most of them have yet to be studied.
On analysing the HAPs identified, the researchers discovered that a particular compound, retene (methyl isopropyl phenanthrene) was present in larger quantities than particles smaller than 10 μm.
On repeating the experiment using only this compound, at the concentrations found in the field, they found that retene can by itself provoke DNA damage and cellular death. (SciDev.Net)
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