ROCHESTER, N.Y., March 5 (UPI) -- U.S. researchers at the University of Rochester Medical Center found that polyaromatic hydrocarbon benzo(a)pyrene, or BaP, found in smoke, slows bone healing.

"Our results provide the first evidence that BaP prevents stem cells from becoming cartilage cells as part of healing," study investigator Dr. Regis J. O'Keefe said in a statement. "These findings extend our understanding of the impact of cigarette smoke on a process that is critical to fracture repair."

The study compared the effect of BaP versus that of cigarette smoke extract, a substance representing all the ingredients in cigarette smoke. The results suggest BaP alone may responsible for this specific mechanism of healing delay, since its effect was equal to the extract.

"Smoking reduces the rate at which the two sides of a fracture come together," Michael Zuscik said. "We believe this new research will establish for the first time the mechanisms by which polyaromatic hydrocarbons interfere with the healing process."

The findings were presented at the annual meeting of the Orthopaedic Research Society in San Francisco.