The threshold values for EAS systems are established in the standard EN 50364. The recommendations of the International Commission on Non-Ionizing Radiation Protection (ICNIRP) are the scientific basis for these threshold values.
The threshold values are established in relation to the operating frequency. Several threshold values apply because the EAS systems work on different frequencies. After all, the possible biological effects differ: low frequencies in the body cause different effects than higher frequencies.
• Electromagnetic alternating fields in the frequency band 1 Hz - 10 MHz can generate an electric current in the body. If the alternating fields are too strong, the generated current can disrupt the functioning of nerves and muscles in the body and cause flashes of light in the field of vision. A threshold value has been imposed on the generated current density in the body so that these effects can be prevented.
• Another effect is generated in the frequency band 100 kHz - 10 GHz: a thermal effect, a warming up effect, as is the case with mobile telephones. This effect is measured in SAR (Specific Absorption Rate) value and expressed in W/kg. A threshold value is imposed for the SAR value to protect against this effect.
• Both effects are present in the frequency band 100 kHz - 10 MHz and both threshold values need to be checked (the threshold values on the current density and on the SAR value).
The SAR value and current density within the body are difficult to measure. That is why reference quantities (electric and magnetic field strength or magnetic flux density) are derived from it and these quantities are easier to measure. It is assumed that the product meets the exposure limits when these reference values for the electromagnetic fields are not exceeded. It is possible that the reference values are exceeded but that the exposure is still under the limits.
The FPS Health, Food Chain Safety and Environment has had a study conducted on the radiation fields of EAS systems.