These days most of us have grown so attached to our phones that being without them almost feels like missing a limb.

We even sometimes sleep near our phones, and it is so tempting to have your mobile with you for some late night Facebook scrolling.

However, this habit is unwise and even unhealthy, warns the California Department of Public Health (CDPH).

The CDPH issued a statement about the dangers of the radio frequency (RF) energy that our smartphones emit. Some scientists are worried that RF energy damages human health.

"Although the science is still evolving, there are concerns among some public health professionals and members of the public regarding long-term, high use exposure to the energy emitted by cell phones," stated CDPH Director and State Public Health Officer Dr. Karen Smith. 

Cell phone manufacturers seem aware of these concerns. As the Daily Mail notes, Apple includes a notice about RF exposure in iPhone's settings, though their RF emissions fall within the US's safety standards. 

Dr. Smith continued, "We know that simple steps, such as not keeping your phone in your pocket and moving it away from your bed at night, can help reduce exposure for both children and adults."

With mobile phone usage on the rise, the CDPH warns that long-term, frequent use of cell phones could lead to brain cancer, tumours of the acoustic nerve (necessary for hearing and maintaining balance) and salivary glands, lower sperm count, inactive sperm, headaches, and learning difficulties. 

However, they clarified that these links are not definitive. The CDPH notes that RF energy is 'not as powerful or as damaging to cells or DNA as some other kinds of electromagnetic radiation, such as X-rays or UV rays from the sun'.

If people want to reduce their RF energy exposure though, the CDPH recommend keeping your phone away from your head or body by using speakerphone or a headset when talking on the phone.

The CDPH urge people to sleep with their phones several feet away unless they are off or in airplane mode. 

They also advised that people send texts rather than speak on their mobiles, as you are more distant from your device then. Carrying your mobile in a bag rather than your bra or pocket also helps to reduce RF energy exposure.

You should distance yourself from your phone when it is downloading or streaming large files, when you are in fast-moving vehicles, or when you have a low cell phone signal (as your phone puts out more RF energy then to connect to a cell tower). 

As well, 'radiation shields' and devices claiming to reduce RF energy or radiation from your phone may actually increase your RF exposure, as your phone emits more RF energy to get past the barriers.