Exposure of preganant women to air pollution is the most likely cause of childhood cancers, suggests a British study published in the Journal of Epidemiology and Community Health.

Carbon monoxide, particulates and nitrogen oxides (which are associated with oil burning, particularly in engines) and non-methane volatile organic compounds (including benzene, 1,3-butadiene, benz(a)pyrene and dioxins) are cited in the research.

Carcinogenic Compounds

Animal research has already identified some of these compounds as carcinogens, says the author, George Knox, Emeritus Professor, University of Birmingham, UK.

Non-methane volatile organic compounds variously reflect solvent use, engine exhaust, fuel evaporation, and other industrial/refinery processes.

Professor Knox based his findings on a chemical emissions map for the UK produced by the UK National Atmospheric Emissions Inventory for 2001 and details of all children who had died from leukemia and other cancers before their 16th birthday in Great Britain between 1953 and 1980.

To compensate for the time lag between the production of the map and the era covered by the death register, only those children dying between 1966 and 1980 were included in the study.

Close Perinatal Encounters with Pollution

When all the data had been compiled and the risks calculated, children born within a 1 kilometer radius of emissions hotspots of particular chemicals were between two and four times as likely to die of cancer before reaching the age of 16 as other children.

Proximity to emissions of 1,3-butadiene and carbon monoxide carried the highest risks.

“Most childhood cancers are probably initiated by close perinatal encounters with one or more of these high emissions sources,” says the author.

The low atmospheric levels of these substances suggest that the mother may breathe them in, with carcinogens passing across the placenta, he ventures. But “effective direct exposures in early infancy, or through breast milk, or even pre-conceptually, cannot be excluded,” Professor Knox concludes.