BRITAIN: Most childhood cancers are probably caused by exposure in the womb to environmental and industrial pollutants that have been inhaled by the mother, according to a British researcher
Prof George Knox, an emeritus professor at the University of Birmingham, compared birth and death records of children who had died from cancer with a chemical emissions map of Britain. His study was published in the Journal of Epidemiology and Community Health.
He found that children born within a 1-km radius of chemical emissions hotspots were two to four times more likely to die of cancer before reaching 16 than other children.
"Most childhood cancers are probably initiated by close perinatal [ around birth] encounters with one or more of these high emissions sources," Prof Knox said.
Being born near high-emission sites of the organic compounds carbon monoxide and 1,3-butadiene carried the highest risks. Carbon monoxide is a product of internal combustion engines and 1,3-butadiene is used to manufacture synthetic rubber and is also a product of internal combustion engines.
"These diseases are determined very early in life, probably prenatally," Prof Knox said in an interview. "They are related to atmospheric emissions that are probably absorbed by the mother and passed across the placenta."
However, Dr Lesley Walker, of the charity Cancer Research UK, said the evidence in the study was thin.
"A wealth of information suggests that leukaemia, the most common type of cancer in children, may be a rare response to an unidentified but common infection," she said in a statement.
"This is a complex area to research - not least because cancers in children are rare and some may have an underlying genetic basis."
The maps used by Prof Knox were produced by the UK National Atmospheric Emissions Inventory. They measured emissions of different chemicals per sq km a year for 2001.
He converted the hotspots into map references and measured the distances between them and the birth and death addresses of the children born between 1960-1980 who had died of cancer.
Childhood cancers occur in about one in 1,000 children but in some of the hotspots it is three or four in 1,000. - Reuters