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 typic
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