Exposure to Smog During Pregnancy Increases Risk of Rare Childhood Cancers

People living in Los Angeles hear reports periodically about the health risks of smog exposure, which has been linked to lung cancer, asthma and other illnesses.

A 2013 study has connected smog exposure during pregnancy and during a child’s first year of life to several rare cancers.

Researchers from the UCLA School of Public Health gathered data on children who were diagnosed with cancer before the age of 6, and exposure to the area’s smog from traffic. The worse the traffic pollution was, the higher the chances were of a child developing lymphoblastic leukemia (white blood cell cancer), germ cell tumors (cancer of the testicles or ovaries), and eye cancer.

While the study’s findings did not prove that pollution causes these cancers, it showed that exposure to traffic pollution may increase the risk for the cancers. Study authors called for more studies, to confirm these findings.

Areas of Southern California, including Los Angeles and Orange counties, and parts of San Bernardino and Riverside counties, are subject to dirtier air than the rest of the country because the area’s surrounding mountains, which block atmospheric air flow, combine with the warm, sunny climate and the high traffic, trapping air pollutants from automobiles, planes, ships, etc., and giving rise to the yellowish haze we know as smog.

Researchers focused on pregnancy because some cancers are known to originate in the womb.

Study researchers collected data for close to 3,600 children under six years of age, who were born between 1998 and 2007 and were listed in the California Cancer Registry. These children were compared to a similar number of healthy children.

The findings showed that the risk for cancer increased with higher exposure to traffic air pollution. Acute lymphoblastic leukemia risk went up by 5 percent; eye cancer risk went up 14 percent; and risk for testicle, ovary and other organ tumors went up 17 percent.

The study did not determine whether any particular period during pregnancy or the child’s first year was especially critical.

The study was presented at an April, 2013 meeting of the American Association for Cancer Research in Washington, D.C. It is the latest indicator that more than just a visibility nuisance, smog can increase the chances of a person developing serious illness. It also underscores that smog can affect not only the respiratory system, as was once believed, but a person’s entire system — and even that of a new life that’s developing inside the person who was exposed.

Previous studies on animals had shown that smog damages cells in the lungs’ airways and reduces the respiratory system’s ability to fight infections and eliminate foreign particles. Children, the elderly, and people with respiratory problems or cardiovascular disease are particularly susceptible to developing health conditions from smog exposure.

By Eirian Hallinan