Children whose mothers have an increased exposure to air pollution from motor vehicles while pregnant may have a higher chance of ­developing certain cancers, a study has found.

Each increase in exposure to ­pollution from gasoline vehicles and diesel trucks was associated with a 4 percent higher risk of developing acute lymphoblastic leukemia, the most common childhood cancer, as well as increased chances of developing rarer cancers of the eye and of cells that form the reproductive system, according to data presented recently at the annual meeting of the American Association for Cancer Research in Washington.

Research in adults has shown that carbon monoxide can damage the retina and have an effect on germ cells of the reproductive system, said Julia Heck, the lead study author. The findings are the first to link air pollution with rarer pediatric cancers, she said.

"With childhood cancers, there's a lot less known about the causes," Heck, an assistant researcher at UCLA's School of Public Health, said in a telephone interview. "My results have to be confirmed in other studies. This is the first real study to report on these rare tumors."

She said it is unknown why exposure to pollution in utero can raise childhood cancer risks.

bloomberg news