THURSDAY, Aug. 19, 2004 (HealthDayNews) -- Preliminary research suggests that benzene emissions from gas stations and auto repair shops may quadruple the risk of leukemia in children.
But the authors of the study, which appears in the September issue of Occupational and Environmental Medicine, caution against overinterpreting the results.
"It is preliminary," said senior author Dr. Jacqueline Clavel, director of research at the French National Institute of Health and Medical Research. The connection could be coincidental, but it does point to the need for further research, she said.
Acute leukemia is the most common childhood cancer. Only a few causes have been identified for the disease in children. However, occupational exposure to benzene -- such as among rubber industry workers -- has been clearly associated with acute leukemia in adults, especially acute non-lymphocytic leukemia, the study said.
According to the study authors, exposure could theoretically also come from unleaded fuel, which contains small amounts of benzene, and from higher air concentrations at gas stations.
While any childhood exposure to benzene would be much lower than that experienced by rubber workers, the authors of this study still felt the possible link merited a look.
The researchers identified 280 cases of acute childhood leukemia, then compared them with an age-matched control group of 258 children without a history of cancer. Almost two-thirds of the children with cancer were 2 to 6 years of age.
Mothers of the children were interviewed about their employment and residential histories.
There appeared to be no definitive association between the mother's occupation while she was pregnant, or the density of residential traffic, and a child's risk of developing leukemia. These findings contradicted certain previous studies.
On the other hand, children who lived near a gas station or an auto repair shop were four times more likely to develop leukemia as children who did not live near these places.
The effect was particularly pronounced for acute non-lymphoblastic leukemia, which was seven times more common among children living close to one of these establishments.
Also, the length of time a child lived near a gas station or service garage seemed to play a role, with the risk of leukemia increasing the longer the child had lived here.
Other experts emphasized that the findings were very preliminary.
"The investigators did not have any direct information on specific chemical exposures and thus allusions to one or another chemical is made without any direct evidence," said Dr. Marshall Lichtman, executive vice president of research and medical programs at the Leukemia & Lymphoma Society in White Plains, N.Y.
"Although rare cases of acute myelogenous leukemia may be induced by benzene exposure, the evidence indicates the risk is a function of the dose of benzene encountered, and the probability of finding that level throughout the neighborhood of a gas station seems improbable. This interesting study, carefully analyzed, requires further confirmation and if confirmed repeatedly, requires the identification of the as-yet unknown causal link between acute childhood leukemia and a particular neighborhood," Lichtman added.
Senior study author Clavel also pointed out the study's limitations. "Information on petrol or benzene was obtained only by interview," she said. "We just asked the mothers if they were living next to a garage or petrol station. It was not a measurement of something exact."
The findings, she stressed, need to be replicated and more precise measurements must be taken.
"The observation is important because there is benzene exposure through petrol," Clavel said. "The exposure is probably very low but we don't know at all what it could do to children."
More information
For more on childhood leukemia, visit the Leukemia & Lymphoma Society.
