A recent study documents a sharp rise in the incidence of salivary gland cancer in Israel that researchers believe may be linked to the use of mobile phones.

The study was commissioned by the Israel Dental Association and directed by Avi Zini of the community dentistry department at the Hebrew University-Hadassah School of Dental Medicine. The study included examination of the incidence of oral cavity cancers in Israel from 1970 to 2006. Among salivary gland cancer cases, researchers found a worrying rise in the number of cases of malignant growth in parotid glands - the salivary gland located under the ear, near the location where cell phones are held during conversations.

By contrast, the incidence of salivary cancers in glands of the lower mouth - the so-called submandular and sublingual salivary glands - remained stable.

From 1980-2002 the number of cases of parotid salivary cancer held steady at around 25 per year. The number of cases rose dramatically in the five years after to 70 cases per year.

"We haven't gathered data on the use of cell phones on the part of the patients," Zini said, "but the rise [in cancer cases] absolutely could indicate increased exposure to cellular telephones and damage caused by radiation."

The researchers intend to collect data on their oral cancer patients' cell phone use during the next stage of the study to examine the possible statistical link between the two.

Of the 11,843 Israelis who developed oral cancers during the period studied, salivary gland cancer was the third most common (at 16.2 percent) after lip cancer and throat cancer. Most oral cancer patients were over 70, with only 2.7 percent under the age of 20.

However, salivary gland cancer, which researchers suspect to be linked to cell phone use, was disproportionately common among young patients. One fifth of those patients were under 20. Oral cancers are associated with a high mortality rate in Israel, with patients living an average of five and a half years. About 2 percent of total cancer cases involve oral cancer.

Warning signs of oral cancer include a white or red spot in the mouth, a sore that does not heal for eight weeks or more, or the appearance of a sore or spot on the tongue. First symptoms of salivary gland cancer include swelling or soreness in the face or neck, a change in the size or shape of one side of the face or dulled feeling or drooping on one side of the face.

A year and a half ago, a study led by Siegal Sadetzki of the Gertner Institute for Epidemiology and Health Policy at Sheba Medical Center, Tel Hashomer, found a link between cell phone exposure and malignant and benign tumors on the head and neck; after five or more years of exposure, a 34 percent rise in the incidence of tumors on the side of the face on which the user holds the cell phone.

The study also noted there was a drop in radiation levels through the use of accessories such as earphones.