References / Safety standards
Safety guidelines watch the rate of field change
Regulatory standardThe rate of change the report measures is also the quantity safety guidelines watch, because a fast enough change is what starts to stimulate nerves. Those limits are written in Tesla per second, where 1 G/us equals 100 T/s.
Where it appears in the report: Executive Summary (Slew Rate), Peak dB/dt Analysis
The evidence
ICNIRP sets its low-frequency exposure limits from the induced electric field, and that field depends on how fast the magnetic field changes. The MRI gradient standard IEC 60601-2-33 limits dB/dt on the same basis. Both come from medical imaging and workplace exposure. So the report uses them as a reference point, not a pass-or-fail mark for a wellness device.
Primary sources
- ICNIRP. Guidelines for Limiting Exposure to Time-Varying Electric and Magnetic Fields (1 Hz to 100 kHz). Health Physics. 2010;99(6):818-836. view
- IEC 60601-2-33. Medical electrical equipment - Part 2-33: Particular requirements for the basic safety and essential performance of magnetic resonance equipment for medical diagnosis (gradient dB/dt limits).
- Peripheral-nerve and cardiac stimulation thresholds (rheobase basis), as summarized in the induced-field safety literature. view