What is the manufacturer's recommended minimum
According to test reports filed with the Federal Communications Commission (FCC), the Specific Absorption Rate (SAR) for the Galaxy S8 for cellular transmission is 0.34 watts per kilogram (w/kg) at the head, and 0.93 w/kg when worn on the body. The WiFi hotspot SAR is 0.95 w/kg. The SAR for simultaneous transmission (cellular plus Wi-Fi) is 1.25 w/kg at the head, 1.39 w/kg when worn on the body, and 1.52 w/kg when used as a hotspot. (1)
All SARs reported above are averaged over one gram of body tissue corresponding to the U.S. standard. The SARs may vary depending upon your specific cell phone carrier.
The FCC ID numbers for the Galaxy S8 are A3L SMG950U, 950U1, and 950W, and for the S8 Plus they are A3L SMG955U, 955U1, and 955W. The SAR values for these smart phones can be found on the FCC website: https://www.fcc.gov/oet/ea/fccid.
For tips on how to reduce exposure to wireless radiation, see "Some Tips to Reduce Your Exposure to Wireless Radiation". (18) In short, limit your use of the phone, keep the phone away from your body whenever it is powered on, use the phone hands-free, and turn off transmitters not in use (e.g., shut off Wi-Fi or use airplane mode).
(7) Environmental Working Group. EWG’s Guide to Safer Cell Phone Use: Where is EWG's cell phone database? August 27 2013.
(17) Joel Moskowitz. Brain Tumor Rates are Increasing in the U.S.: The Role of Cell Phone and Cordless Phone Use. http://bit.ly/risingtumors
(18) Joel Moskowitz. Some Tips to Reduce Your Exposure to Wireless Radiation (one page handout). Undated. http://bit.ly/saferemrtips3