Long term use of cell phone has already been associated with brain tumor. Now a new study suggests that simply carrying a cell phone with talk mode on could damage sperm.

The study by researchers at Cleveland Clinic showed cell phones left on talk mode in a pocket increased oxidative stress and reduced antioxidants in the semen.

Ashok Agarwal, the Director of the Center for Reproductive Medicine and colleagues collected semen samples from 32 men and divided each sample into two parts. One part was placed 2.5 centimeters from an 850 MHz cell phone in talk mode for one hour and the other was not exposed to the radiation.

The researchers found oxidative stress increased and antioxidants decreased in the semen samples exposed to the cell phone radiation. Agarwal was cited by CNN as saying that the effect was equal to a decrease in sperm quality.

This was not the first time that cell phone was found to have a negative effect on the sperm. A few early studies have already associated exposure to cell phone radiation with decreased sperm quality.