Swedish researchers find new PAH in tyres - update

ERJ staff report (DS)

Stockholm - A group of researchers in Stockholm university in Sweden

have found a new set of PAH materials in tyres, according to a paper

published in the journal Environmental Science & Technology, published by the American Chemical Society.

The paper, titled, Automobile Tires-A Potential Source of Highly Carcinogenic Dibenzopyrenes to the Environment,

shows that automobile tyres may be a potential previously unknown

source of carcinogenic dibenzopyrenes to the environment. The paper

abstract said, “Previously, there have been no data available for

carcinogenic dibenzopyrene isomers in automobile tyres.”

The researchers tested eight tyres tyres were purchased in the EU and manufactured in the time interval 2005 to 2006. They were analysed for 15 high molecular weight (HMW)

polycyclic aromatic hydrocarbons (PAH), using pressurized fluid

extraction.

In the paper, the researchers say, “In this study, the four

dibenzopyrene isomers dibenzo[a,l]pyrene, dibenzo[a,e]pyrene,

dibenzo[a,i]pyrene, and dibenzo[a,h]pyrene constituted <2 percent of

the sum of the 15 analysed HMW PAHs.”

These PAH materials are not covered by the existing ban on high PAH oils in tyres -- and indeed the tyres were not covered by the ban, having been made before the ban was imposed. Roger Westerholm, one of the researchers told ERJ, "The source of PAHs to tires is believed to be both the extender oils and the carbon black used as reinforcing material. With the ban of highly aromatic oil used as extender oils in the rubber manufacturing, the PAH content in the tires will probably be decreased, however, it is necessary to investigate what significance carbon black has to the PAH content. If the dibenzopyrene content is lowered as well is not known. Further research is needed."

He said the full text of the paper addresses these issues in more detail.

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Abstract of paper from ACS