Pollution May Cause Child Cancers

April 10, 1997

NEW YORK (Reuters) - Children born near sources of atmospheric and industrial pollution are about 20% more likely to die of leukemia and solid tumor (nonblood) cancers before they reach adulthood, British researchers say.

The findings further confirm fears of environmental health experts that air pollution may be an even greater threat to children in industrialized areas than lead exposure.

In a report in the Journal of Epidemiology and Community Health this week, researchers from the University of Birmingham Medical School in England report on their study of children who died of leukemia and cancer in Great Britain. From their previous studies, these researchers had found that childhood leukemias and cancers tended to occur "in small geographical clusters."

Among the more than 22,400 fatal childhood cancer cases that occurred in England, Scotland, and Wales between 1953 and 1980, the authors identified geographic patterns where the risk was greater for homes near industrial sites. "Childhood cancers are geographically associated with two main types of industrial atmospheric effluent, namely: (1) petroleum derived volatiles; and (2) kiln and furnace smoke and gases, and effluents from internal combustion engines," write the researchers.

Children born up to 3 miles (5 kilometers) from producers, refiners and industrial users of petroleum fuel and volatile petroleum products (including solvents, paints, fiberglass, plastics, and varnish) were in the group having the highest number of childhood cancer deaths.

"Relative excesses of leukemias and of solid cancers" were also found among children born near car-manufacturing plants; plants using high-temperature furnaces such as steelworks, cement and brick factories; and crematoria. Children living near major roadways, railways, harbors, and airfields - all sites involving combustion engines - also figured significantly in the increased cancer deaths.

The authors note that birthplace hazards appear to carry more risk for childhood cancer than addresses to which the children subsequently moved. "We conclude that early exposure is the more important," the authors state. "For children who had moved house between birth and death, the proximity effect was limited to the birth addresses."

To explain the increased cancer deaths, the researchers say they believe that the risk lies in "direct exposure of pregnant women or young children to airborne substances diffusing into the surrounding environment." They note these substances also can combine to form "secondary pollutants" - other hazardous compounds, including ozone -- which may exert their own carcinogenic effects.

The researchers also note there are "many less obvious" sources of potentially hazardous air pollution, including hospital and municipal incinerators, gas stations, and radon seepage from home sites.

Other possible causes of childhood cancers include "gamma radiation, medical radiation, ambient electromagnetic fields, infections of mother or child, and prenatal drug exposures."

"Patterns of exposure could be far more intricate than our present results have indicated," conclude the researchers.

SOURCE: Journal of Epidemiology and Community Health (1997;51:151-159)

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