Iron in particulate matter damages lungs

Published: Saturday 15 February 2003

-- (Credit: Emkay)they are small, almost undetectable; but their adverse impacts are very apparent, at times lethal. A new study, once again, narrates the nightmarish story about how small-sized particulate matter (pm) invades our lungs much more fiercely as compared to their bigger counterparts. The study provides a breath of fresh air to those struggling to find a plausible account of how pm harms.

Numerous studies have associated short-term increases in pm concentration to a rise in mortality resulting from respiratory and cardio-vascular diseases. Unfortunately, very few have examined the properties of pm that are responsible for the adversities.

The latest study was conducted by researchers from the us-based Utah State University, the University of California and the Ford Motor Company. They hypothesised that metals released within the epithelial cells (lungs' first line of defence) catalyse the formation of inflammatory substances that damage the lungs.

To scientifically validate their hypothesis, the researchers studied how iron (one of the major components of pm) affects cultured epithelial cells. The researchers studied the affects of iron present in pm of coal fly ash, gasoline emissions, diesel exhaust, natural soils, and the ambient air of Utah. For all five, they found that the levels of iron increased with a decrease in the size of pm. As a result, these particles damaged the lungs more, as compared to the larger ones.

Furthermore, the researchers observed that pm stimulated the syn-thesis of a protein called ferritin in the cells. The protein binds iron and thus prevents it from damaging the cells. But to their utter horror, the researchers found that when the levels of iron are too high, then ferritin stops functioning and even releases whatever iron it has absorbed. The iron provokes an inflammatory response by forming reactive oxygen species, which lead to the production of inflammatory substances like interleukin-8.

The researchers conclude that there may be multiple mechanisms by which inhaled pm produces adverse health affects. Therefore, further research to identify all pm characteristics is important to develop effective and appropriate air quality regulations.

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