TUESDAY, April 9 (HealthDay News) -- Exposure to air pollution
during pregnancy and the first year of life might increase the
likelihood of developing certain childhood cancers, California
Researchers from the University of California, Los Angeles
School of Public Health collected data on children diagnosed with
cancer before the age of 6 and local traffic exposure. The greater
the traffic pollution, the higher the odds for acute lymphoblastic
leukemia (white blood cell cancer), germ cell tumors (cancers of
the testicles, ovaries and other organs) and eye cancer, they
These findings do not mean pollution actually causes these
cancers, said lead researcher Julia Heck, an assistant researcher
in the department of epidemiology. "This finding is an association,
because nothing is proven yet," she said.
But the results do suggest that exposure to traffic pollution
might increase risk for childhood cancers, Heck added. "Since this
was the first study to report risks for these [uncommon childhood]
cancers, these findings need to be confirmed in other studies," she
Areas of California are known for their unhealthy air. The
state's topography and its warm, sunny climate tend to form and
trap air pollutants, creating smog, according to the California Air
The researchers focused on pregnancy because certain cancers
originate in the womb, Heck said.
But women shouldn't worry about their baby's risk for cancer
based on this study, another expert said.
"There has been an association between air pollution and other diseases," said Dr. Rubin Cohen, director of the Adult Cystic Fibrosis and Bronchiectasis Center at the Long Island Jewish Medical Center in New Hyde Park, N.Y. "We know that pollution causes asthma, and that is probably more real than the cancer issue."
Cohen isn't sure the association between pollution and childhood
cancers is causal, and he said there isn't much one can do about it
anyway. "Moving is easier said than done," he said.
The study findings were scheduled for presentation Tuesday at
the annual meeting of the American Association for Cancer Research
in Washington, D.C.
For the study, Heck's team collected data on nearly 3,600
children under 6 years old who were born between 1998 and 2007 and
listed in the California Cancer Registry. The researchers compared
them with a similar number of healthy children.
The researchers were able to estimate the amount of traffic
pollution at each child's home during the mother's pregnancy and
the child's first year of life. The estimates included exposure to
gas and diesel engines as well as traffic volume, emission rates
Based on their findings, Heck's group concluded the risk for
cancer was increased with higher exposure to vehicular air
pollution. "In terms of the risk, greater exposure was associated
with a 5 percent increase in [acute lymphoblastic leukemia]
cancers, an 11 percent increase in eye cancer and a 15 percent
increase in testicle, ovary and other organ tumors," Heck said.
But whether any particular period is critical during pregnancy
or the child's first year wasn't clear.
Another expert agreed that more research is needed before
conclusions can be drawn about any actual risk for cancer from
The study needs to be replicated to see if the same findings are
seen in other cities, said Dr. Guillermo DeAngulo, a pediatric
oncologist at Miami Children's Hospital, in Florida.
"There has been a concern about environmental factors playing a role in cancers," said DeAngulo, who was not involved in the study. "The question is how much of a role they play."
Genetic components also may be involved that may make cancer
more likely for some of these children, he said.
Data and conclusions presented at meetings are typically
considered preliminary until published in a peer-reviewed medical
For more information on air pollution, visit the
U.S. National Library of Medicine.
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