We all know cell phones can heat up if used consistently over a long period of time, but how hot can they get? And are they safe?

One woman in Hunan doesn’t think so. She claims her iPhone 5s got so hot it burned her face. Doctors at the Zhuzhou People’s Hospital say the burn marks are indeed the result of “electric radiation burn”.

It all happened in July, when Su Jing from Zhuzhou, Henan was having a long talk on her iPhone 5s. During the call, Su felt her phone getting hot, so she switched to speaker phone. After the call she noticed a burning sensation on the left side of her face, but didn’t think anything of it.

Su only discovered the mark when she went to work the next day. She then went to a clinic, but was redirected to a hospital where she received her diagnosis. Su has reported the case to Apple, the manufacturer of the iPhone 5s, but has not received any answers so far.

She first went to an authorized Apple re-seller, but was told they wouldn’t be responsible for any injuries. When Su called the Apple customer service hotline, she was told she would first need to return the phone before Apple could make any kind of decision. However, Su said she’s unwilling courier the phone as nobody would be responsible for it if something happened to it in transit.

Su went back to the re-seller, which called Apple to verify if it can accept the phone on Apple’s behalf. However, there has been no reply. Su said she was told by Apple a month ago that the company would look into it, but she still hasn’t received a response.

A report in the Chinese media decided to test how hot cell phones can get during continuous use. Three phones were used in the experiement: an iPhone 5S, a Samsung Galaxy Note 2, and a Huawei G700.

After one hour of continuous use an infrared thermometer showed that screens on two of the phones reached a temperature of 40 degree Celsius. After 90 minutes, they reached temperatures of 49 degrees Celsius. The report didn’t say which two phones heated up the most.

Photo: XXCB