Studykids' cancers to moms' exposure to pollutants

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Study links kids' cancers to moms' exposure to pollutants

 

By ANDRÉ PICARD

PUBLIC HEALTH REPORTER

Tuesday, January 18, 2005 - Page A17

http://www.theglobeandmail.com/servlet/ArticleNews/TPStory/LAC/20050118/HCANCER1\

8/TPHealth/

 

Most childhood cancers are likely caused by pollutants expectant mothers

are exposed to during pregnancy, according to a new study. Those at

greatest risk live close to busy roads and industrial areas, researchers

found.

 

In particular, they found children born of mothers living near " emission

hot spots " of particular chemicals were two to four times more likely to

develop leukemia and other childhood cancers before age 16.

 

" Most childhood cancers are probably initiated by close, perinatal

encounters with one or more of these high-emission sources, " said George

Knox, a professor emeritus at the University of Birmingham in

Birmingham, U.K.

 

Emissions that appear to raise cancer risk the most include carbon

monoxide created by burning fossil fuels (notably gasoline used by

vehicles) and 1,3-butadiene, also a by-product of internal combustion

engines. Researchers also looked at the effect of various other

industrial and environmental pollutants, including particulate matter,

nitrogen oxides (both of which are associated with oil burning), as well

as dioxins, benzene, and benz(a)pyrene. These chemicals can be found in

engine exhaust, and smokestack emissions from various industrial and

refinery processes.

 

Dr. Knox said these chemicals -- many of which have been shown to be

carcinogenic in animal tests -- are likely breathed in by the mother and

passed on to the baby through the placenta. But he said that " effective

direct exposure in early infancy, or through breast milk, or even

preconceptually, cannot be excluded. "

 

The study is published in today's edition of the Journal of Epidemiology

and Community Health.

 

The study did not deal with how the chemicals might trigger the growth

of tumours. Instead, it focused on the location of children who

developed cancer. To conduct the research, Dr. Knox and his team used

detailed chemical-emission maps produced by the U.K. National

Atmospheric Emissions Inventory, and crossreferenced them with the home

addresses of children who died of cancer.

 

There were a total of 22,458 childhood cancer deaths in Great Britain

between 1953 and 1980. Eleven varieties of cancers were recorded,

including leukemias, lymphomas, neuroblastoma and bone cancers.

 

Dr. Knox and his team found that the cancer deaths were concentrated

near emissions " hot spots. " In fact, children within a one-kilometre

radius of a hot spot -- such as a large industrial plant or a major

highway -- were two to four times more likely to die of cancer.

 

Some cancer experts, however, said the study was highly speculative and

dismissed the notion that " most " childhood cancers are caused by

exposure to pollutants.

 

Dr. Lesley Walker of Cancer Research U.K. said, for example, that there

is a growing body of evidence that leukemia may be a rare response to a

common infection. It is also well established that some cancers, such as

neuroblastoma (a tumour that develops in the adrenal glands or certain

nerves), can be caused by nutritional deficiencies, specifically a lack

of folate. " This is a complex area to research -- not least because

cancers in children are rare and some may have an underlying genetic

basis, " she said.

 

Almost 1,300 children are diagnosed with cancer in Canada each year, and

about 230 die, according to the National Cancer Institute of Canada.

Almost one-third of the cases and the deaths are due to various forms of

leukemia.