Apple says it has not seen any evidence to back up a French newspaper’s claim that Mac Pros are emitting toxic odors, including benzene.

The report, first appearing in Libération and picked up by tech blogs in the U.S., contends Mac Pros built before 2008 emit an odor. A scientist quoted in the article says the odor contains several toxins, including benzene. Prolonged exposure to benzene raises the risk for diseases, including cancer.

While not dimssing the reports, Apple noted that it hadn’t found any evidence to prove the claim.

“We have not found anything that supports this claim, but continue to investigate it for the customer,” Apple spokesman Bill Evans told Macworld.

Apple has taken steps in recent years to remove hazardous materials from its products. In 2007, the company began phasing out the use for flourescent lamp in its LCDs to elimante the presence of mercury. In a 2007 open letter on the company’s environmental policies, CEO Steve Jobs said that Apple products complied with European Union restrictions on chemicals such as cadmium, hexavalent chromium, and decabromodiphenyl ether.