According to the National Institute of Justice Law Enforcement and Corrections Standards Testing Program for Hand-Held and Walk-Through Metal Detectors:
2.2.1 Safety Specifications and Requirements
Physical contact to voltages exceeding a particular value can be dangerous. HH and WT units should not expose the user or public to high-voltage electrical signals or power. If high voltages do exist within or on these devices, then these devices must be enclosed so as to prevent user access to the high voltages. Underwriters' Laboratories (UL) provides a standard for exposure to voltages that is referenced in the NIJ standard.
Another safety concern is more mechanical or physical in nature. The operator or another person coming into contact with the HH or WT unit should not be exposed to needless risk of injury. The HH and WT unit should not contain sharp edges, loose covers/cowlings, hanging wires, protruding surfaces, etc. To address this concern, the detector is required to have rounded corners, no external wires or cables to trip over, and no loose parts. Violations of these safety requirements would be obvious, but unless stated explicitly, manufacturer compliance cannot be assumed.
Magnetic fields are used by HH and WT units to sense the presence of metal objects. Scientific studies have raised the concern that exposure to magnetic fields may cause biological changes in living cells. The effect of exposure of biological tissue and systems (human bodies) to magnetic fields has been addressed by several standards-setting organizations, and these standards are used in the revised NIJ standard to limit human exposure to magnetic fields generated by HH and WT units.
In addition, certain types of personal medical electronic devices may be affected by these magnetic fields. However, the effect of magnetic fields on personal electronic medical devices has not been studied extensively. These devices may be implanted under the skin or attached to the surface of the skin and include cardiac defibrillators, pacemakers, infusion pumps, spinal cord stimulators, ventilators, etc. At the time of this writing, only a few manufacturers of HH and WT units have had the effect of their detectors on personal medical electronic devices tested; and this was only for cardiac pacemakers. The Center for Device and Radiation Health (CDRH) of the Food and Drug Administration (FDA) is the Federal organization responsible for determining safety of exposure to various types of radiation. The CDRH has defined exposure limits for laser sources, cabinet x-ray machines, microwave ovens, etc. At the time of this writing, however, the CDRH has not declared any formal opinions regarding the exposure of the various personal medical electronic devices to the magnetic fields generated by hand-held and walk-through metal detectors.
220.127.116.11 Warning Labels
A warning label is required on HH and WT units until the FDA or a similar agency has determined that exposure to the magnetic fields generated by HH and WT units is not unsafe.