US researchers warn of the dangers of toxic dust

Dust blown up from agricultural and industrial sites could be a major health hazard warn Arizona scientists, who have drawn up maps showing health risk areas.

Researchers from Arizona State University are advising that chronic inhalation of fine dirt that settles into homes in the Phoenix area could lead to an increased risk of cancer or heavy metal poisoning, and have developed a new series of maps from satellite images in order to identify areas where health risks are likely.

Agriculture and industry can cause the danger from toxic dust by introducing the substances into the soil, says William Stefanov, a geologist on the team. “Pesticides and herbicides can be applied for years in some areas, and that material doesn’t just disappear in the soil. It has a very long residence time.” The toxins adhere to soil particles and are carried on the wind along with the dust, and if the dust is inhaled by people of animals, so are the toxins. “The biggest problem comes when there’s a large-scale disruption of the surface, like a construction project,” said Stefanov. “When the soil has been broken up, the fine material, where a lot of these pesticides and heavy metals might be, is free to be picked up by the wind.” Frequent watering of the ground surface during construction would help to minimise the transport of this dust, the research team advises.

“Dust has been known as a health hazard for at least 20 years,” said Stefanov. “In the [the area], there’s certainly a potential health risk.” The damaging health effects of breathing dust depend on the amount of exposure, he explained. “If you drive through a dust cloud and breathe some dust, it’s probably not going to hurt you. But if you live down-range of an industrial site or some area where dust is always being generated and you’re always breathing this stuff, then you might have something to worry about,” said Stefanov.

Recently, public concern about dust-borne pathogens from outside the US was raised when marine biologists blamed the rapid demise of Caribbean corals on attacks by a fungus carried in Saharan dust. Saharan dust has also been found in the US Virgin Islands, containing heavy metals, bacteria, fungi, and what appeared to be viruses. Major storms in the Gobi desert of Mongolia and China have also moved dust containing pollutants such as arsenic and toxins from burning fossil fuel into air currents crossing the Pacific Ocean, with one massive cloud recently reaching the western US before dispersing (see related story).

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