Work solvent-related brain tumor concerns allayed

By Helen Albert, Senior MedWire Reporter

There is no consistent evidence for increased risk for glioma or meningioma following occupational exposure to chlorinated solvents, say researchers.

We did find some evidence suggesting a positive association between carbon tetrachloride and glioma, notes the team, but this was not conclusive.

Exposure to chlorinated solvents has been linked to various types of cancer including leukemia, lymphoma, and kidney and urinary tract cancer. An increased incidence of brain tumors has also been observed in people whose work involves a higher than average exposure to chlorinated solvents such as painters, electricians, and metal workers.

Gila Neta (National Cancer Institute, National Institutes of Health, Bethesda, Maryland, USA) and colleagues investigated whether exposure to six chlorinated solvents - dichloromethane, chloroform, carbon tetrachloride, 1,1,1-trichloroethane, trichloroethylene and perchloroethylene - increases a person's risk for glioma or meningioma.

They enrolled 489 glioma, and 197 menangioma patients, as well as 799 controls for the hospital-based case-control study.

For each participant, chlorinated solvent exposure was investigated and the following information recorded: ever/never exposure, duration of exposure, cumulative exposure, average weekly, and highest exposure.

In an analysis restricted to a small group of exposed individuals, the researchers found that an average weekly exposure to carbon tetrachloride above the median was linked to a significant 7.1-fold increased risk for glioma compared with below-median exposure (confidence interval 1.1-45.2).

However, no other associations between solvent exposure and glioma or meningioma were observed.

"We found no consistent evidence of an increased risk of glioma or meningioma related to occupational exposures to any of six chlorinated solvents, though there was limited evidence of a positive association between carbon tetrachloride and glioma," write Neta et al in Occupational and Environmental Medicine.

They add that their "results raise questions as to whether exposure to chlorinated solvents is the relevant hazard underlying the reported increased risk of glioma among electrical and electronics workers," as well as in other related professions.

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