But manipulation by the industry had begun almost immediately at the start of research. While Dr. Carlo and his team had never defined their research as being done to prove the safety of cell phones, the industry internally defined it as an insurance policy to prove that phones were safe. From the outset, what was being said by the cell phone industry in public was different from what was being said by the scientists behind closed doors.
I really want to caution you to be careful of any "expert" or EMF blogger recommending anti-radiation filtering cases, stickers that attach to the phone or necklaces to "ward off" EMF.  I get it, when I first realized 25 years ago that I was sensitive to electromagnetic energy and then later, when I understood that without a doubt, man made electromagnetic radiation has a biological effect on my body, I wanted an easy fix.  I tried the shielding materials and cases and I just did not feel any better.  Then I bought meters to see if the energy changed and I actually noticed what the California Department of Health now says and it's what the FTC and FCC post warnings about:  "Some shielding materials can make exposures worse". So please, be careful and read on for what you can do to avoid electromagnetic radiation exposure.
Today’s report, the final one, was about a decade in the making and is the last of several versions that have been released since preliminary results were presented in May 2016. It represents the consensus of NTP scientists and a group of external reviewers, according to the release. In the future, the NTP plans to conduct studies in smaller exposure chambers and to use biomarkers such as DNA damage to gauge cancer risk. These changes in the experimental setup should mean that future studies will take less time.
The World Health Organisation (WHO) released a fact sheet about these issues, shortly after the IARC re-classification, entitled "Electromagnetic fields and public health: mobile phones". The fact sheet points to the findings of the IARC and describes some of the known short-term and long-term effects of phone use, but ultimately, it lands on the side of where the most conclusive evidence exists:
The amount of RF energy absorbed from the phone into the user’s body is known as the specific absorption rate (SAR). Different cell phones have different SAR levels. Cell phone makers are required to report the maximum SAR level of their product to the US Federal Communications Commission (FCC). This information can often be found on the manufacturer’s website or in the user manual for the phone. The upper limit of SAR allowed in the United States is 1.6 watts per kilogram (W/kg) of body weight.

The World Health Organization (WHO) says the intensity of radio frequency (RF) radiation from cell phones decreases exponentially the further the device is held away from the body. Therefore your safest bet it keep your cell phone as far away from your ear and body as possible at all times. Don’t carry it in your pocket, tucked into a bra strap, and definitely don’t sleep with it next to your head.
The first one is easy, cellular frequencies vary between 450–2000MHz, but 800 or 900 MHz is the most common. The power emitted by a cell phone varies over the course of the call (higher when making initial contact, which lasts a few seconds). It can go up to 2 Watts at the start of a call, and can go down to .02 Watts during optimal operation [2]. Of course, most people barely use cell phones for calls, but I am using this example as a worst case scenario, because the phone is not right by your head when you are browsing Tinder.

Mobile or cell phones are now a days an integral part of modern telecommunications in every individual life. In many countries, over half of the population use mobile phones and the mobile phone market is growing rapidly. Saudi Arabia rank first among the countries of the gulf region with highest proportion of mobile users, a study conducted by United Nations Conference on Trade and Development (UNCTAD). In gulf countries, Oman ranked second, followed by Kuwait and the UAE. As billions of people use mobile phones globally, a small increase in the incidence of adverse effects on health could have major public health implications on long term basis. Besides the number of cell phone calls per day, the length of each call and the amount of time people use cell phones are important factors which enhance the health related risk. (1)
Just as inevitably, worries about brain cancer spawned a market for products that supposedly protect cell phone users. For $62, you can order a Delta Shield, a thin polyester patch that contains a microchip that allegedly renders cell phones harmless. Users are instructed to place the patch on their cell phone battery. The similar BIOPRO Cell Chip, sold online for $35, attaches to the outside of the phone. The penny-size WaveShield 2000 Gold, selling for about $25, fits on the earpiece.
In 2011, the International Agency for Research on Cancer (IARC), a component of the World Health Organization, appointed an expert Working Group to review all available evidence on the use of cell phones. The Working Group classified cell phone use as “possibly carcinogenic to humans,” based on limited evidence from human studies, limited evidence from studies of radiofrequency radiation and cancer in rodents, and inconsistent evidence from mechanistic studies (4).
The frequency of radiofrequency electromagnetic radiation ranges from 30 kilohertz (30 kHz, or 30,000 Hz) to 300 gigahertz (300 GHz, or 300 billion Hz). Electromagnetic fields in the radiofrequency range are used for telecommunications applications, including cell phones, televisions, and radio transmissions. The human body absorbs energy from devices that emit radiofrequency electromagnetic radiation. The dose of the absorbed energy is estimated using a measure called the specific absorption rate (SAR), which is expressed in watts per kilogram of body weight.