UA Researchers Report Potential Health Risks of 'Green' Fuel

Feb. 22, 2001

Kate Jensen
UA Children's Research Center

Worldwide shortages of fossil fuel combined with concerns about the greenhouse effect are creating demand for "green," or environmentally friendly, fuels. One possible fuel source, dried municipal sewage sludge (MSS) is a potential health hazard according to a study by University of Arizona researchers published this week in Nature, an international weekly journal of science.

MSS is the mud-like material that remains after the treatment of wastes that flow into local sewage treatment plants. After it is sterilized, it can be used as a fertilizer but it also is being considered for use as a "green" fuel. MSS is "CO2 neutral," meaning it does not lead to a net increase of carbon dioxide in the atmosphere.

"But the fact that a fuel is CO2 neutral does not mean it is entirely safe," says Jost O.L. Wendt, head of the UA department of chemical and environmental engineering. "The message we hope to send is that the use of MSS as a 'green fuel' should be considered with care."

Wendt is the research co-coordinator for an international team of engineers and scientists who are investigating the relationship between sources of fine particle emissions and their health effects.

Most industrialized nations are looking at ways to reduce CO2 emissions by exploring biomass fuels such as wood, straw, sugar cane, ethanol or MSS.

The University of Stuttgart, another member of the research team, provided ash samples of burned MSS combined with coal for a pilot study. Experiments conducted in the Lung Injury Laboratory of the UA Children's Research Center showed that the MSS/coal mixture emits particles that cause significantly more lung damage than those from coal alone.

"Airborne particulate matter is an important environmental issue because of its association with acute respiratory distress in humans," says Mark Witten, UA research professor and head of the UA Lung Injury Lab.

"It is important to note that not all particulates are created equally," Wendt says. "Current standards limit the size of particulates, not composition. With the mixture of MSS and coal, zinc appears to be the bad actor." (Zinc is an oxidizing agent that can react chemically in lung tissue.)

This research was an international collaborative project funded by the Japanese New Energy & Technology Development Organization (NEDO).


Resources for the media