By Oregon State University, June 6, 2014
Researchers at Oregon State Univ.
have discovered novel compounds produced by certain types of chemical
reactions — such as those found in vehicle exhaust or grilling meat —
that are hundreds of times more mutagenic than their parent compounds,
These compounds were not previously known to exist, and raise
additional concerns about the health impacts of heavily-polluted urban
air or dietary exposure. It’s not yet been determined in what level the
compounds might be present, and no health standards now exist for them.
The findings were published in Environmental Science and Technology.
The compounds were identified in laboratory experiments that mimic
the type of conditions which might be found from the combustion and
exhaust in cars and trucks, or the grilling of meat over a flame.
“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,” says 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 says.
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, believed to be more of a health concern
that has been appreciated in the past, and are the subject of extensive
research at OSU and elsewhere around the world.
The PAHs can become even more of a problem when they chemically
interact with nitrogen to become “nitrated,” or NPAHs, scientists say.
The newly-discovered compounds are NPAHs that were unknown to this
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. Mutagens are chemicals that can cause DNA damage in
cells that in turn can cause cancer.
For technical reasons based on how the mutagenic assays are
conducted, the researchers says these numbers may actually understate
the increase in toxicity – it could be even higher.
These discoveries are an outgrowth of research on PAHs that was done
by Simonich 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
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.