Traffic-related air pollution and acute childhood leukemia in France: findings from the nationwide GEOCAP study
Introduction: Several environmental factors are suspected of contributing to the development of acute leukemias (AL), the most frequently diagnosed cancers in children under 15 years of age. Among these factors, traffic-related air pollution has attracted particular attention. Certain pollutants, such as benzene and fine particulate matter, have been classified as proven human carcinogens by the International Agency for Research on Cancer (IARC), based on studies conducted in adults. In children, some studies have suggested an association between air pollution and the risk of leukemia, but this link remains to be clarified. The objective of this study was to evaluate whether exposure to traffic-related pollutants increases the risk of acute lymphoblastic leukemia (ALL, representing 80% of AL) and acute myeloid leukemia (AML, 15% of AL) in children.
Methods: Data from the nationwide case-control study GEOCAP-Diag were used. This study included 4,611 ALL cases and 830 AML cases diagnosed between 2002 and 2013, identified through the National Childhood Cancer Registry (https://rnce.inserm.fr/en/), as well as 60,189 controls randomly selected from tax databases. Annual average concentrations of traffic-related pollutants (nitrogen dioxide, fine particulate matter, and black carbon, a component of fine particulate matter) were estimated at the children’s residential addresses at the time of diagnosis for cases and at the time of inclusion for controls. In addition, the length of major roads (with high traffic) within a 150-meter radius of each child’s home was assessed.
Results: Higher concentrations of nitrogen dioxide, fine particulate matter, and black carbon at the children’s residences were associated with an increased risk of AML. Similarly, a greater length of major roads surrounding the residence was associated with a higher risk of AML in children. These effects were particularly pronounced in highly urbanized areas. In contrast, no increased risk of ALL was observed with any of the traffic-related exposure indicators.
Conclusion: The results of this study highlight an effect of exposure to traffic-related air pollutants on the risk of AML, supporting the potential role of these pollutants in the development of certain pediatric leukemias.
By Charlotte Salmon
