Smog Exposure during Pregnancy Might Raise Child's Cancer

Risk: Study

Exposure to air pollution during pregnancy and the first year of life might increase the likelihood

of developing certain childhood cancers, California researchers say.

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

found.

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 said.

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

Resources Board.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 and weather.

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 traffic pollution.

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 journal.

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