The most effective technique for protecting yourself against the dangers of cell phone radiation is keeping the phone at a distance from the body. Simply using a hands-free headset is a big step. Headsets keep the cell phone’s antenna at a distance of six to seven inches away from the body, thus eliminating near-field exposure. Wired headsets can act as an antenna to draw some ambient EMR, but not much, so using one is still preferable to holding the phone to your head. Wireless headsets should be avoided, as they draw much more far-field EMR.
The safest headsets have hollow air tubes, similar to those used in stethoscopes, instead of wires.They offer protection against both near-field and far-field exposure. If possible, avoid wearing the phone at your waist, which exposes the hip bones to radiation. Eighty percent of red blood cells are formed in the hip bones. There are also newer cell phones available capable of functioning in speaker phone mode. This enables you to talk on the phone while keeping it at a safe distance from your body. If you are able to conduct most of your conversations using a speaker phone, this could enable you to use a cell phone without encountering the intense radiation exposure that occurs when holding it to your ear.
Source:
https://www.amazon.com/dp/B014NJXVZO/ref=pd_lpo_sbs_dp_ss_1?pf_rd_p=1944687442&pf_rd_s=lpo-top-stripe-1&pf_rd_t=201&pf_rd_i=B003AO55JY&pf_rd_m=ATVPDKIKX0DER&pf_rd_r=7Q3Y3R0B5H10PPNCPZKS
http://www.lifeextension.com/Magazine/2007/8/report_cellphone_radiation/Page-02