Smoke from forest fires may contain potent mutagenic compounds that can damage human DNA, according to a controversial new study of fire emissions.
Researchers found nitrogen-rich alkaloids in smoke billowing from a controlled burn of Ponderosa pine trees in Missoula, Montana.
The findings could have significant health implications for those downwind of forest fires, especially smouldering, low-temperature fires such as prescribed burns that produce more smoke than higher-temperature wildfires.
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The presence of alkaloids 鈥� naturally occurring toxins produced by trees and other plants 鈥� has long been suspected in smoke from forest fires, but the new study is the first to detect the compounds coming directly from a blaze.
of the Pacific Northwest National Laboratory in Richland, Washington, and colleagues made their discovery using a specialised device to collect ultra-fine particles from the smoke of a forest fire. They then used high-resolution mass spectrometry to determine which molecules the particles contained.
Laskin says the alkaloids can be transported hundreds or even thousands of miles and play an important role in cycling nitrogen through ecosystems, but also have the potential to be quite harmful.
鈥淪ome of them are really toxic,鈥� says Laskin. 鈥淚t鈥檚 very well known that when cows, for example, eat pine needles they die. In a forest fire you emit aerosols into air that contain those same compounds.鈥�
鈥榃arning flag鈥�
Ralph Propper, an air pollution specialist at the isn鈥檛 so sure.
鈥淚鈥檇 be more concerned about eating heavily charred meat,鈥� says Propper, referring to the well-documented carcinogenic affects of burnt food.
He says the study鈥檚 claim that alkaloids produced by plants can alter or damage genes is an overstatement. 鈥淭hat鈥檚 just not accurate, a very minor percentage of alkaloids are mutagenic,鈥� he says, noting that caffeine and cacao (the key ingredient in chocolate) are also alkaloids.
Propper, emphasising that he is stating his opinion and not that of the CARB, goes on: 鈥淭he pine needles of Ponderosa pine are toxic to some degree 鈥� that鈥檚 how they defend themselves, with alkaloids 鈥� but there isn鈥檛 anything in this paper to show that they are mutagenic.鈥�
The study鈥檚 main shortcoming is that it identifies classes of compounds found in smoke rather than specific compounds, he says. 鈥淚t certainly gives a warning flag that the possibility for mutagenic or carcinogenic compounds exists, but they need to do a lot more work to establish that,鈥� says Propper.
Journal reference: (DOI: 10.1021/es803456n)
