Cell phone use increases the amount and flow of saliva, suggesting that frequent cell phone users slobber more, dental researchers claim.

Indian researchers from the Vidhya Shikshan Prasark Mandal's Dental College and Research Center, looked into how heat and radiofrequency emitted from cell phones can affect adjacent tissues by observing parotid glands, or saliva producing glands in the jaw, of heavy cell phone users.

The study consisted of 142 men and women, between the ages of 18 and 30, who had used cell phones for three or more years. None of the participants had oral complaints, disorders or medication use that could affect salivation and none had a medical history of systemic disorders affecting the head, neck or face.

Participants were divided into two groups of heavy users and control subjects. The heavy-user group made up of 50 men and 50 women who used their phones for more than two hours a day on average and the control group made up of 20 men and 22 women who used their phones for less than two hours a day.

Researchers measured the parotid glands in their resting state by recording unstimulated parotid salivary flow rate and taking ultrasound images of the glands.

Compared to the control group, researchers found that people who used cell phones for more than two hours a day have significantly larger parotid glands with higher levels of blood flow. Heavy cell phone users produced and secreted 26 percent more saliva on the side of the face where they typically hold their mobile phone.

Additionally, 30 percent of participants in the study reported other problems after cellphone use with 35 percent reporting ringing and heating of the ear and skin, 7 percent reporting headaches and 5 percent suffering from migraines.

Researchers noted that because the study only found a correlation between saliva production and phone usage, it cannot be concluded that frequent cell phone use directly caused more saliva secretion.

However, the findings may suggest that electromagnetic radiation from mobile devices could stimulate parotid gland growth and therefore their subsequent increased saliva production, but additional tests are needed to establish the actual cause.

"This study observed functional and volumetric changes induced in parotid glands are associated with excessive mobile phone use," the study authors concluded.

Researchers note that previous studies have found that radiofrequency radiation and heat generated by the phone can physically affect users, suggesting that "longer use of mobiles can potentially raise skin temperature and increase perfusion of the tissue to reduce the raised temperatures," researchers wrote.

The study was published in the journal Oral Surgery, Oral Medicine, Oral Pathology and Oral Radiology.