Gas Emission at Birth Linked to Kids Cancer?
Study Shows Research Should Look at Timing of Exposure to These Chemicals, Concentrate on Solutions
Jan. 18, 2005 -- New research from the U.K. shows that prenatal exposure to gas emissions is a major cause of childhood cancers, but an expert contacted by WebMD remains skeptical.
The study showed that children in the U.K. living within about a half mile of a gas emission "hotspot" at birth were between two and four times as likely as other children to die of cancer prior to reaching their midteens.
The study's author contends that prenatal exposure to engine exhaust is responsible for the majority of childhood cancers. E.G. Knox, who is an emeritus professor at the University of Birmingham, says future research into the causes of cancer in children should focus on environmental exposures in the womb as well as during childhood.
What We Know
Knox tells WebMD that the findings also show the importance of reducing air pollution. While he agrees that we should work harder to reduce the level of carcinogens in the atmosphere, American Cancer Society spokesman Herman Kattlove, MD, says the U.K. study falls far short of proving a link between a baby's exposure in the womb to gas emissions and childhood cancer.
Cancer is relatively rare in children, with one to two cases occurring among every 10,000 children, according to U.S. figures. A recent report from the National Cancer Institute concluded that the cause of most childhood cancers is "largely unknown."
The report noted that a few conditions, such as Down syndrome and other identified genetic abnormalities explain a small percentage of childhood cancers. Radiation exposure has also been implicated, but the vast majority of cancers in children have no obvious cause.
"Environmental causes of childhood cancer have long been suspected by many scientists but have been difficult to pin down, partly because cancer in children is rare, and partly because it is so difficult to identify past exposure levels in children," the report stated.
Carbon Monoxide, 1.3-Butadiene
In the newly published study, Knox compiled data on birth and death addresses for children in the U.K. who died of cancer between 1966 and 1980. He then used a national map detailing chemical emission hotspots to calculate the risk of cancer based on where the children were living at birth and at the time of their deaths.
He concluded that children born within 1 kilometer (0.62 miles) of emissions hotspots for particular chemicals were at increased risk. Carbon monoxide and 1.3-butadiene (a gas made from the processing of petroleum), both carried the highest risk. A lower, but still elevated, risk was seen for exposure to the chemical benzene, which has been implicated in other studies as a cause of leukemia.
The findings are published in the latest issue of the Journal of Epidemiology and Community Health.
Kattlove, who is a medical oncologist and editor for the American Cancer Society, says Knox fails to present the necessary data to prove his claim that environmental exposure early in life or prior to birth is a major cause of childhood cancer.
He adds that if gas emissions are the main source of childhood cancers, then tougher emission standards should have led to a reduction in such cancers. While death rates among children with cancer have declined dramatically thanks to better treatment, rates of childhood cancers remained steady or even increased for specific malignancies.
"The proof just isn't here," he tells WebMD. "I think everyone agrees that we need to regulate atmospheric emissions, but this study doesn't prove the association with childhood cancer."