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Electronic article surveillance systems

  • Essentially, electronic article surveillance systems in department stores all operate according to the same principle: the detection zone consists of a magnetic or electromagnetic field and is generally located in the checkout area or at the store exit.
  • Tags attached to the articles are detected using either low-frequency magnetic fields or high-frequency electromagnetic fields.
  • Electronic article surveillance systems can lead to high levels of exposure.
  • Recommendation: as a customer, walk through the detection or screening zone quickly and, if possible, through the middle. Wherever possible, you should neither stop inside the detection zone itself nor touch or lean on the transmitting antennas.

Electronic article surveillance systems are intended to prevent theft in department stores. Depending on the nature of the objects being protected, either a hard tag or a sticky label is attached to the articles. If the tag or label is not deactivated or removed from the article before a person passes through the detection zone of an EAS system with it, the system triggers an alarm.

Technologies used

Electronic article surveillance system Electronic article surveillance systemElectronic article surveillance system

A variety of technologies are currently used to detect tags by means of either low-frequency magnetic fields or high-frequency electromagnetic fields, operating either with continuous signals or with different pulse shapes. In many cases, there is a lack of detailed information about the frequencies and pulse shapes used or about the intensity of the magnetic or electromagnetic fields.

Essentially, all systems operate according to the same principle: the detection zone consists of a magnetic or electromagnetic field and is generally located in the checkout area or at the store exit. This field is produced by a transmitter generating low- or high-frequency signals. If an active security tag passes through the detection zone, the field is disrupted and an alarm is triggered.

Because of the way the devices work, the area with the highest field strength is located between the transmitter units. Outside of the detection zone, the field strength decreases rapidly with increasing distance.

Electronic article surveillance systems can lead to high levels of exposure

Exposure measurements have shown that systems using low-frequency fields (“acousto-magnetic” or AM systems; typical operating frequency: 58 kilohertz), can result in pulse peaks with a magnetic flux density of over 200 microtesla (µT). The reference level of 38 microtesla developed by the International Commission on Non-Ionizing Radiation Protection (ICNIRP) with respect to the general public was still exceeded at a distance of half a metre from the transmitting antennas.

Values exceeding the reference levels have also been detected with systems using higher frequencies in the region of 8 megahertz (“radio-frequency” or RF systems) and with systems operating at lower frequencies (“electromagnetic” or EM systems). Equipment that operates at frequencies between 2,400 and 2,500 megahertz is very rare in practice. No specific information is available for such equipment.

Research

If the reference levels proposed by ICNIRP are exceeded, it is necessary to carry out detailed investigations for the purposes of a health assessment. The BfS had already commissioned investigations of this kind as part of two research projects. The investigations highlighted significant technology-specific differences:

  • In systems with an operating frequency of around 8 megahertz (RF systems), the investigations gave no indication that decisive base values (specific absorption rates and electric field strength values in the body) for health protection in this frequency range are exceeded, even if unfavourable exposure conditions are assumed.
  • Systems that operate using low-frequency magnetic fields with a frequency of around 58 kilohertz (AM systems) can exceed the decisive base value (electric field strength in the body) for this frequency if a person approaches the transmitting antennas to a distance of some 20 centimetres or less.
  • In the case of systems that operate at even lower frequencies (EM systems), the possibility of exceeding the base value for the electric field strength in the body was only observed in extreme proximity to the transmitting antenna.

If the base value is exceeded, health-relevant effects can occur with increasing exposure level. These are acute effects that only occur for the duration of the increased exposure and cease if the person moves out of the field. The effects do not occur in every individual, as the base value lies well below the threshold above which effects have been demonstrated experimentally. The decision to define a base value that is significantly below the effect threshold reflects, among other things, the fact that people can react to the corresponding fields with different degrees of sensitivity.

Health Assessment

Although the overall health risk can be assessed as low based on current scientific knowledge, levels that exceed the base values are to be avoided in all circumstances in accordance with the fundamental principles of radiation protection.

There is scientific uncertainty as to the possible long-term effects at field intensities below the recommended limit values. Much less research has been carried out into the health risks due to magnetic fields with frequencies in the kilohertz range than into risks due to exposure in other frequency ranges. However, customers generally only find themselves within the area of influence of EAS systems for a short period of time. The contribution of these systems to customers’ overall exposure and therefore to a possible long-term risk can therefore be assumed to be low. As a precautionary measure, exposure to low- or high-frequency fields should generally be kept as low as possible.

Recommendations

for customersShow / Hide

  • As a customer, walk through the detection or screening zone quickly and, if possible, through the middle.
  • Wherever possible, you should neither stop inside the detection zone itself nor touch or lean on the transmitting antennas.

for people with active and passive medical devicesShow / Hide

Special precautionary measures are advisable for people with active or passive medical devices (such as cardiac pacemakers, infusion pumps or artificial joints):

  • Implants made entirely or partly of metal can lead to a concentration of the electric fields that are produced in the body. The base value recommended to protect health may therefore be reached even at larger distances from the sources of fields. If you have implants of this kind, you should pay particular attention to the following guidelines:

    • Walk through the detection zone quickly and as close to the middle as possible.
    • Wherever possible, do not stop within the detection zone.
    • Do not touch or lean on the transmitting antennas.
  • As the operation of active implants could be affected, people with an active implant (such as a cardiac pacemaker) should, as a precaution, never remain inside the field area for longer than is absolutely necessary. In other words, they should walk through the systems as quickly as possible and, in the event of queues in the checkout area, avoid standing between the detectors.

for shopkeepers/branch managersShow / Hide

Products are exhibited in the detection zone. Customers who wish to examine the products are forced to stand within the detection zone. Incorrectly positioned goodsProducts are exhibited in the detection zone. Customers who wish to examine the products are forced to stand within the detection zone.

  • If, as a shopkeeper or branch manager, you consider electronic article surveillance systems to be essential, you should only install systems that result in low levels of exposure. Studies have found that systems with an operating frequency in the megahertz range (RF systems) are more favourable than devices that use low-frequency fields (EM systems and above all AM systems with a frequency of 58 kilohertz).
  • Configure the detection thresholds of electronic article surveillance systems so as to avoid unnecessarily high levels of exposure.
  • Keep the screening zone clear of goods displays (“bargain bins”) and other incentives that could cause customers to linger within the magnetic or electromagnetic fields (see image).
  • Install the pedestals so as to also minimise exposure of employees (such as checkout or security staff). Account must also be taken of the fields produced by equipment for deactivating product tags in the checkout area.

Requirements

for the manufacturers of implants and for doctorsShow / Hide

To reduce the risk of affecting the operation of active medical devices:

  • manufacturers of active medical devices should develop devices that are as interference-proof as possible
  • doctors should favour interference-proof medical devices when treating their patients, avoid using interference-prone implantation techniques, and take care to use less interference-prone device configurations
  • health insurance funds and doctors should provide affected patients with suitable information.

In addition, further knowledge is needed about the causes of the effect on medical implants in order to reduce their sensitivity to electromagnetic interference.

for the manufacturers of electronic article surveillance systemsShow / Hide

  • Manufacturers should only use technologies that result in low levels of exposure. The possibility of levels that exceed the base values must be reliably ruled out for people of any size, including children, in all reasonably foreseeable circumstances.
  • Electronic article surveillance systems should be clearly identifiable to customers as sources of magnetic or electromagnetic fields and should be labelled as such. Concealed systems – e.g. in the floor – that are not identifiable as sources of electromagnetic fields should be avoided for reasons of radiation protection.
  • Manufacturers should make people with implants aware of potential interference by labelling the systems appropriately.
  • Manufacturers of electronic article surveillance systems should disclose the technical characteristics of their systems so as to allow radiation protection experts to assess the potential health effects. Ensuring the lowest possible exposure of the general public must be a key objective during the system’s development, and the exposure of staff must also be taken into account. Employees are exposed not only by the detectors but also by equipment for activating and deactivating the tags.
State of 2023.11.14

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