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SAR / Device Absorption

A method for safety testing of radiofrequency/microwave-emitting devices using MRI.

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Alon L, Cho GY, Yang X, Sodickson DK, Deniz CM. · 2014

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Cell phones operating at maximum power for 15 minutes caused 1.7°C tissue heating, proving wireless devices create measurable biological effects within safety limits.

Plain English Summary

Summary written for general audiences

Researchers developed a new method using MRI to measure how much radiofrequency energy devices like cell phones deposit into body tissues by tracking temperature changes. When they tested a cell phone at maximum power for 15 minutes, it caused tissue heating of 1.7°C and delivered energy at 0.54 watts per kilogram. This technique provides a more accurate way to test whether wireless devices meet safety limits for human exposure.

Why This Matters

This study represents a significant advance in how we measure the biological impact of wireless devices. The science demonstrates that even at maximum power output, cell phones can cause measurable tissue heating - a 1.7°C temperature rise in just 15 minutes. What this means for you is that your phone is depositing enough energy to create detectable biological changes in real time. The reality is that current safety testing relies heavily on computer modeling rather than direct biological measurement. This MRI-based approach provides hard evidence of how RF energy actually behaves in tissue, giving us a clearer picture of exposure levels. The 0.54 W/kg SAR reading for the cell phone falls within current regulatory limits, but the measurable heating confirms that biological effects occur at approved exposure levels.

Exposure Details

SAR
0.54, 11.9, 12.4 W/kg
Exposure Duration
15 min

Exposure Context

This study used 0.54, 11.9, 12.4 W/kg for SAR (device absorption):

Building Biology guidelines are practitioner-based limits from real-world assessments. BioInitiative Report recommendations are based on peer-reviewed science. Check Your Exposure to compare your own measurements.

Where This Falls on the Concern Scale

Study Exposure Level in ContextStudy Exposure Level in ContextThis study: 0.54, 11.9, 12.4 W/kgExtreme Concern - 0.1 W/kgFCC Limit - 1.6 W/kgEffects observed in the Extreme Concern rangeFCC limit is 3x higher than this level

Study Details

We investigated the application of MR temperature mapping and 10-g average specific absorption rate (SAR) computation for safety evaluation of RF-emitting devices.

Quantification of the RF power deposition was shown for an MRI-compatible dipole antenna and a non-M...

The maximum temperature change for a dipole antenna and the maximum 10-g average SAR were 1.83°C and...

Information acquired using MR temperature mapping and thermal property measurements can assess RF/microwave safety with high resolution and fidelity.

Cite This Study
Alon L, Cho GY, Yang X, Sodickson DK, Deniz CM. (2014). A method for safety testing of radiofrequency/microwave-emitting devices using MRI. Magn Reson Med. 2014 Nov 25. doi: 10.1002/mrm.25521.
Show BibTeX
@article{l_2014_a_method_for_safety_807,
  author = {Alon L and Cho GY and Yang X and Sodickson DK and Deniz CM.},
  title = {A method for safety testing of radiofrequency/microwave-emitting devices using MRI.},
  year = {2014},
  
  url = {https://pubmed.ncbi.nlm.nih.gov/25424724/},
}
PubMed: 25424724

Cited By (20 papers)

Quick Questions About This Study

Yes, cell phones can cause measurable tissue heating. A 2014 MRI study found that a cell phone operating at maximum power for 15 minutes heated body tissues by 1.7°C (3°F), demonstrating that radiofrequency energy from phones does transfer heat into human tissue.
Research using MRI temperature mapping found that a cell phone at maximum output delivers energy at 0.54 watts per kilogram into body tissue. This measurement technique provides accurate data on how much radiofrequency energy penetrates and heats human tissue during phone use.
Cell phone radiation does cause measurable biological effects like tissue heating. A 2014 study documented 1.7°C temperature increases in tissue after 15 minutes of maximum phone use, showing that radiofrequency energy produces real physical changes in the body.
Yes, phone radiation measurably increases body temperature. MRI research demonstrated that cell phones operating at full power for 15 minutes raised tissue temperature by 1.7°C, proving that radiofrequency emissions from phones create detectable heating effects in human tissue.
Wireless devices can heat body tissues through radiofrequency energy absorption. Research shows cell phones at maximum power cause 1.7°C temperature increases in 15 minutes, indicating that prolonged or high-power wireless device use may pose thermal risks to human tissue.