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Roadsides
polluted by catalytic converters
By
Amy Geiszler-Jones
Catalytic
converters – the devices on cars that remove gaseous pollutants
– are spewing out some other potentially toxic elements that
are building up along U.S. roads, according to a study co-authored
by a WSU researcher.
Mark
Schneegurt, an assistant professor in biological sciences, and four
researchers from the University of Notre Dame have conducted one
of the most comprehensive U.S. studies of roadside contamination
by catalytic converters.
Catalytic
converters have been used on U.S. cars since 1978 to turn toxic
pollutants such as carbon monoxide and hydrocarbons into less harmful
emissions through chemical reactions. The material used to speed
up those reactions is filled with platinum, palladium and rhodium,
known collectively as platinum-group elements or PGEs.
The
elements are emitted as microscopic particles from your vehicle’s
tailpipe. The level and rate of PGE release are affected by a number
of things, including how fast you’re driving and the type of
engine in your vehicle.
And
enough of those elements are being spewed out that they are building
up to potentially harmful levels along roadsides and as far as 55
yards from the roads, the study showed.
"There’s
so much of it that it’s almost worth it to mine the top inch
of roadside dust" for the three elements, says Schneegurt.
Platinum
is highly allergenic. If people are consistently exposed to certain
allergens at even low levels they can develop allergies that can
lead to asthma, or they can experience other symptoms such as sensitive
skin. Not enough research has been done on palladium and rhodium
to determine how harmful they are, Schneegurt says.
PGE
buildup could lead to other problems, considering a number of U.S.
roads cut through agricultural areas, Schneegurt notes. It’s
not known if the elements are getting into groundwater supplies
or the wildlife and human food chains.
The
researchers collected soil samples from urban roads and side streets
in and around South Bend, Ind., where Notre Dame is located. They
also went to several sites along Interstate 80 between South Bend
and Chicago, collecting roadside samples and soil samples at five,
10 and 50 meters from the road.
There’s
the potential for even more elements to be emitted: The Clean Air
Act of 1990 requires converters to be attached to small gas engines
such as those on lawn mowers and chain saws.
"Catalytic
converters do far more good than harm, but we don’t want to
replace one problem with another," Schneegurt says.
He
hopes the study will cause manufacturers to consider making changes
to the converters.
The
study was published in a recent issue of the American Chemical Society’s
journal Environmental Science & Technology.
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