- DENVER, Colorado (ENS) -
Children living near heavily traveled streets or highways are at greater
risk of developing cancer, including childhood leukemia, a new study conducted
in the rapidly expanding Denver metropolitan area shows.
- When researchers looked at the occurrance of cancer in
children living in homes close to both high traffic corridors and high
current capacity power lines, they found the cancer risks were greater
than in children in high density traffic areas alone.
- The study was authored by Robert Pearson of Denver,s
Radian International, University of Colorado at Boulder electrical engineering
Professor Howard Wachtel and Kristie Ebi of the Electric Power Research
Institute in Palo Alto. It was published in the February 2000 issue of
the "Journal of the Air and Waste Management Association."
- "What we are seeing is that children who live near
high traffic streets have an increased risk for childhood cancer,"
said Pearson, also an adjunct professor of urban planning at CU-Denver.
"What we have not yet been able to pin down is the specific cause
and effect relationship."
- The new study showed that homes adjacent to street corridors
carrying 20,000 or more vehicles per day had roughly a six-fold increase
in risk for children contracting cancer, including childhood leukemia,
- Motor vehicles are a significant source of air pollution
emissions, including benzene and other organic compounds, said Pearson.
Occupational exposure to elevated concentrations of benzene is a known
cause of leukemia in adults.
- The researchers found a correlation between high volumes
of traffic on streets or highways near homes where incidences of childhood
cancer previously had been documented.
- A 1989 Study by University of North Carolina researchers
David Savitz and Lisa Feingold linked heavily trafficked Denver streets
to confirmed cases of childhood cancers on the specific streets, said Wachtel.
But the effect of heavy traffic on nearby thoroughfares was not taken into
account, leaving the study open to criticism.
- But the new study takes into account the neighboring
traffic in several ways, including adjustments for the distance between
the highest traffic streets and homes up to 1,500 feet away. This allowed
the researchers to consider the typical pattern of dispersion and decay
of drifting vehicle emissions as they migrated from the traffic corridors
outward to homes under study.
- For example, a house used as a control in the study or
a house with a confirmed case of childhood cancer might be located in a
quiet cul-de-sac. But if it also is only a few hundred feet from an interstate
highway, the volume of highway traffic weighed heavily in assessing the
traffic exhaust exposure for that dwelling, Wachtel said.
- The authors also speculated that children living near
heavily trafficked streets could be exposed to benzene and other carcinogens
via inhalation or exposure to soil where vehicle emission chemicals may
- A study in Stockholm several years ago in which researchers
looked at nitrogen dioxide pollution from vehicles and cancer rates of
nearby residents found a correlation, although not as strong as the one
in the new Denver study, said Pearson. Another study in Great Britain showed
a correlation between childhood cancer and the proximity of children,s
homes to steel mills, factories and high traffic streets, he said.
- Savitz, a former professor at the CU Health Sciences
Center, had previously worked with Wachtel, CU-Boulder Professor Frank
Barnes and several other researchers on a 1988 study that linked Denver
childhood cancers to high current capacity power lines common along high
density traffic corridors. But that research and subsequent studies around
the world failed to pinpoint a specific cause and effect relationship between
the electromagnetic fields generated by the power lines and cancer.
- For their study, Pearson, Wachtel and Ebi obtained street
traffic densities for 1979 and 1990 from the Colorado Department of Transportation
and the Denver Regional Council of Governments. The years 1979 and 1990
were closest to the period of exposure addressed in the 1988 power line
cancer study from which the specific cases and locations of childhood cancer
were drawn for the new study.
- Children living in homes close to both high traffic corridors
and high current capacity power lines show more elevated risks for cancer
than children living only in high density traffic areas, Wachtel said.
- "It,s possible that benzene and other organic compounds
from vehicle exhaust may initiate cancer in children while EMF,s [electro-magnetic
frequencies] may act to promote such cancers," he said. "We need
to design some well thought out follow up studies, since there is still
a lot we don,t understand about the associations involving cancer, high
density traffic and EMFs."
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