Air Pollution Exposure in Pregnancy Linked to Cancers

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 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 today 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. Today’s 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 the University of California, Los Angeles, School of Public Health, said in an April 5 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.

California Registry

Researchers in the study looked at 3,590 children from the California Cancer Registry who were born from 1998 to 2007 and linked to a California birth certificate. The researchers then looked at 80,224 others who had California birth certificates. They estimated the amount of local traffic exposure at the mother’s home during each trimester of pregnancy and the child’s first year.

They found that each increase of 53 parts per billion of carbon monoxide pollution raised the risk of a child developing certain cancers, Heck said. Each increase raised the risk of developing retinoblastoma, or cancer of the eye, by 14 percent, and cancer of the germ cells by 17 percent.

The researchers weren’t able to break down at what point during pregnancy the pollution may increase the risk of cancer because pollution levels were fairly consistent, Heck said. Those with the highest exposures lived near highways or heavily trafficked roads.

About 11,630 U.S. children younger than 15 will be diagnosed with cancer this year, according to the American Cancer Society. The number of cases has increased slightly over the past few decades. Leukemia accounts for about 1 of every 3 cancers in children and the majority of those leukemia diagnoses are acute lymphoblastic leukemia, which is cancer of the blood and bone marrow, according to the cancer society.

Cancer of the eye, called retinoblastoma, affects about 200 to 300 children each year in the U.S. Most of the children have a tumor in only one eye, the society said on its website.

Germ cell tumors account for about 3 percent of all childhood cancers, according to the University of Texas MD Anderson Cancer Center website.

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