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OSU to study air pollutant's impact on Chinese, U.S. health
April 28, 2009
Chemist Staci Simonich and graduate student Wentao Wang examine a vial containing air pollutants at a lab at Oregon State University. Simonich is training Wang, who is from Peking University, so he can help with research about the impact of polycyclic aromatic hydrocarbons on the health of Chinese and U.S. residents. Photo by Tiffany Woods.
CORVALLIS, Ore. – Scientists at Oregon State University and China's Peking University plan to use part of a $12.4 million grant to study the impact that the burning of fuels like coal and biomass – as well as the smoking of meat – may have on the health of residents of China and the United States.
Additionally, the research will help determine the cancer-causing potential of certain air masses and where they came from, said OSU chemist and toxicologist Staci Simonich, the lead U.S. researcher on the project.
The research, funded by the National Institute of Environmental Health Sciences, will focus on air pollutants called polycyclic aromatic hydrocarbons (PAHs). They're produced when biomass (like straw and wood) and fossil fuels (like coal and gas) are burned as well as when meat is smoked or grilled. PAH compounds, some of which have been shown to cause cancer in humans, can attach to particles, like soot, and blow thousands of miles through the air and settle in the bottoms of lakes and rivers.
In China, which is a huge consumer of coal and a major emitter of PAHs, researchers will measure how much and what types of PAHs Chinese residents in 12 homes in the Beijing and Tianjin area are inhaling over the course of two years, starting in 2010. They'll analyze the urine of the 30 participants to find out what types of PAHs they’re exposed to. They’ll also ask them to wear air sampling devices, including ones that are worn as backpacks and have a motor that sucks in air. Air samplers will also be placed inside and outside their homes as well as in six locations throughout the Beijing and Tianjin area.
"The combined information on which PAH metabolites people are excreting and which PAHs are in air will help us identify the sources of the PAHs," said Simonich, who is a member of a National Academy of Sciences panel that studies air pollutants entering and leaving the United States.
The Chinese participants will live in three settings: urban apartments that use natural gas for cooking and heating, suburban residences that use coal stoves for these two purposes, and farm houses that use coal and biofuels to do so.
Across the Pacific Ocean in Oregon, air samplers will be set up at the Confederated Tribes of the Umatilla Indian Reservation. Scientists will also ask a handful of tribal members to wear air samplers on several occasions while they're curing fish and game in smokehouses, which produce PAHs. Urine samples will be taken before and after the food smoking events.
Scientists selected these two groups because they wanted to study populations that were exposed to PAHs but from apparently different sources to understand how the different PAH mixtures are metabolized in the body and excreted in urine.
The tribal members, however, might not be inhaling PAHs solely from the smokehouses, said Anna Harding, an OSU public health professor who is one of the leaders of the portion of the project involving the American Indians. Their reservation is downwind of a coal-fired power plant in Boardman, Ore., and it's also home to a truck stop where diesel exhaust is emitted. Additionally, it's in an agricultural area where some fields are burned.
Also as part of the project, scientists will collect air samples from Okinawa, Japan; Portland, Ore.; a rural site in Oregon's Clackamas County; and Mount Bachelor, which is near Bend, Ore. However, people at these sites won't be asked to wear air samplers. Instead, samples will be taken using stationary equipment.
"This combination of sites will help the team understand if PAH emissions from Asia increase the PAH concentrations in populated areas of the western United States," Simonich said.
After collecting air samples, researchers will test the PAHs on bacteria to assess possible damage to DNA. They'll also test them on zebrafish, pregnant mice, and human lung and liver cell lines to find out if the PAHs cause cancer.
Scientists will also see if the PAHs morph, through photochemical reactions, into cancer-causing nitro- and oxy-PAH compounds as they attach to particles and are blown across the ocean to the West Coast of the United States. This will help the researchers understand if the air masses that reach the United States are more or less toxic than when they left Asia.
With additional funding from the National Science Foundation, researchers will simulate this transformation in laboratories at OSU and the University of Bordeaux in France so they can better understand how the changes in chemical composition happen.
The air sampling sites were selected for strategic reasons. Okinawa was chosen because it's downwind of Asia and because Simonich previously conducted research there that traced PAHs back to China. Portland was selected because it's home to a low-elevation urban setting, and researchers want to know if the air masses from Asia, which typically travel at higher elevations, swoop that low, Simonich said. Clackamas County was chosen because it's downwind of Portland.
Mt. Bachelor made the list because its roughly 9,000-foot summit is accessible by chairlift and its high elevation makes it a good place for capturing pollutants from Asia, Simonich said. Additionally, she and her team have been collecting air samples there since 2004 and have detected chemicals from pesticides, fossil fuels, nonstick cookware coatings and stain-repellants. They traced them back to Asia, California, Oregon and Washington using computer models that followed the path of winds. Their findings have been published in the journal Environmental Science & Technology.
In her new research, Simonich will be collaborating with professor Shu Tao at Peking University. She worked with him last summer while monitoring the air quality in Beijing before and during the Olympics.
Source: Staci Simonich, Anna Harding