Traffic-related air pollution raises childhood cancer risk, study finds

Sustained exposure to traffic-related air pollution significantly raises the risk of childhood cancer, particularly childhood leukemia, a new study has found.

The National Cancer Center announced Sunday that a joint domestic and international research team, including Kim Byung-mi of the center's cancer prevention division, confirmed the findings through a meta-analysis.

The study was conducted under the Korea-US Childhood and Adolescent Cancer Consortium, a collaboration involving researchers from Ewha Womans University College of Medicine — including principal investigator Ha Eun-hee, Yoo Eun-sun and Surabhi Shah, as well as researcher Oh Jong-min — along with Kim Byung-mi of the National Cancer Center and teams from the University of Minnesota and Boston College. The research received support from the Ministry of Health and Welfare's National Cancer Control Program research and development project on cancer survivor care and cancer prevention technology.

The team reviewed 1,632 studies published between 1990 and 2024, ultimately selecting 25 for a systematic literature review and meta-analysis.

The analysis focused on the association between childhood cancer incidence and exposure to three major traffic-related air pollutants: fine particulate matter (PM2.5), nitrogen dioxide (NO2) and benzene.

The results showed a clear trend: as concentrations of air pollutants increased, so did the risk of childhood cancer.

For every 10 micrograms per cubic meter increase in PM2.5 concentration, the risk of childhood acute lymphoblastic leukemia (ALL) rose by 29 percent, while the risk of retinoblastoma, a type of pediatric eye cancer, increased by 68 percent.

Each 1 microgram per cubic meter increase in benzene concentration was associated with a 12 percent rise in overall childhood leukemia risk and a 22 percent increase in the risk of acute myeloid leukemia (AML).

The researchers also compared exposure timing before and after birth, finding that postnatal exposure to traffic-related air pollutants during infancy and early childhood was more closely linked to increased leukemia risk than prenatal exposure.

Unlike adult cancers, childhood cancers are driven less by acquired lifestyle factors such as smoking, alcohol consumption and diet, and more by the interaction between genetic factors and exposure to environmental hazards.

The researchers said air pollutants, once absorbed into the body, promote inflammatory responses and induce oxidative stress, likely causing DNA damage in children's cells that can ultimately develop into cancer.

The study is considered significant for providing robust evidence of a link between traffic-related air pollution and elevated childhood cancer risk, drawing on a meta-analysis that synthesizes global research accumulated over more than 30 years.

The findings also underscore the need for tailored environmental health policies and air pollution reduction measures to protect children and pregnant women, who absorb pollutants at higher rates and are more vulnerable than adults due to incompletely developed physiological systems.

"This study systematically demonstrates that exposure to traffic-related air pollution can increase the risk of certain childhood cancers, including leukemia," Kim said. "Policy efforts to more aggressively reduce air pollutants and continued follow-up research are essential to protect the health of children, who represent the next generation."

The findings were published in Environmental Research (impact factor: 7.7), an international journal in the field of environmental health.