7.5 RF SAFETY PHILOSOPHY

The purpose of RF exposure guidelines is not to eliminate every interaction between electromagnetic fields and the body. Small biological responses can occur without impairing health, just as ordinary activity and changes in ambient temperature produce measurable physiological responses. The objective is to prevent established adverse health effects.

Guideline development begins by identifying adverse effects supported by the weight of evidence and determining the exposure conditions associated with them. Where the evidence supports a lowest exposure level known to cause an effect, this is identified as the adverse-health-effect threshold. Where a sufficiently precise threshold cannot be obtained, or related evidence indicates that harm could occur below it, a conservative operational threshold is used. Reduction factors are then applied to the relevant threshold or operational threshold to account for scientific uncertainty, differences among people, environmental conditions, dosimetric uncertainty, and other protective assumptions.

Protection is based on the physical quantities responsible for interaction rather than transmitter power alone. Identical transmitter powers can produce very different exposures because of frequency, antenna gain and direction, distance, duty cycle, field region, reflections, shielding, and source-body coupling.

The framework therefore combines health-based basic restrictions with conservative reference levels that can be assessed in practice. It also distinguishes controlled occupational exposure from general-public exposure and provides special treatment for brief, localized, and non-uniform exposures.

Exposure restrictions do not address every possible safety issue. Electromagnetic compatibility of implanted devices, contact with energized conductors, secondary injuries, and workplace operating controls may require separate device, equipment, or occupational safety provisions.