CORVALLIS, Oregon, January 6, 2014 (ENS) – Newly identified compounds produced by chemical reactions in vehicle exhaust or by grilling meat are hundreds of times more mutagenic than their cancer-causing parent compounds, according to scientists at Oregon State and three other universities.
These compounds were not previously known to exist, and they raise concerns about the health impacts of heavily-polluted urban air and dietary exposure, the researchers said. It is not yet clear in what amounts the compounds might be present, and no health standards now exist for them.
The highly mutagenic compounds were identified in laboratory experiments that mimic the conditions that might be found from the combustion and exhaust in cars and trucks, or the grilling of meat over a flame.
A mutagen is a chemical that changes the genetic material of an organism, increasing the frequency of mutations above the natural background level. As many mutations cause cancer, mutagens are likely to also be carcinogens.
The parent compounds involved in this research are polycyclic aromatic hydrocarbons, or PAHs, formed naturally as the result of almost any type of combustion, from a wood stove to an automobile engine, cigarette or a coal-fired power plant.
Many PAHs, such as benzopyrene, are known to be carcinogenic. They are believed to be more of a health concern that has been appreciated in the past and are the subject of extensive research at Oregon State University and elsewhere around the world.
PAHs can become even more of a problem when they chemically interact with nitrogen to become “nitrated,” or NPAHs, the scientists warn. The newly-discovered compounds are NPAHs that were unknown until now.
“Some of the compounds that we’ve discovered are far more mutagenic than we previously understood, and may exist in the environment as a result of heavy air pollution from vehicles or some types of food preparation,” said Staci Simonich, a professor of chemistry and toxicology in the OSU College of Agricultural Sciences.
“We don’t know at this point what levels may be present, and will explore that in continued research,” she said.
This study found that the direct mutagenicity of the NPAHs with one nitrogen group can increase six to 432 times more than the parent compound.
NPAHs based on two nitrogen groups can be 272 to 467 times more mutagenic than the parent compound.
For technical reasons based on how the mutagenic assays are conducted, the researchers said these numbers may actually understate the increase in toxicity. It could be even higher.
These discoveries are an outgrowth of research on PAHs that Simonich did at the Beijing Summer Olympic Games in 2008, when extensive studies of urban air quality were conducted, in part, based on concerns about impacts on athletes and visitors to the games.
Beijing, like some other cities in Asia, has significant problems with air quality, and may be 10-50 times more polluted than some major urban areas in the U.S. with air concerns, such as the Los Angeles basin.
An agency of the World Health Organization announced last fall that it now considers outdoor air pollution, especially particulate matter, to be carcinogenic, and cause other health problems as well.
PAHs are one of the types of pollutants found on particulate matter in air pollution that are of special concern.
Concerns about the heavy levels of air pollution from some Asian cities have prompted Simonich to conduct air quality monitoring on Oregon’s Mount Bachelor, a 9,065-foot mountain in the central Oregon Cascade Range.
Researchers want to determine what levels of air pollution exist there after the air has traveled thousands of miles across the Pacific Ocean.
This research was supported by the National Institute of Environmental Health Sciences and the National Science Foundation. It is also an outgrowth of the Superfund Research Program at Oregon State University that focuses efforts on PAH pollution.
Researchers from the OSU College of Science, the University of California-Riverside, Texas A&M University, and Peking University collaborated on the study.
The findings were published in December 2013 in the journal “Environmental Science and Technology.”