SAR Values in Electronic Devices: How to Interpret Them and What They Mean for User Safety

Mobile devices have become a fundamental part of contemporary life, and with this widespread diffusion, it is essential to ensure that prolonged use of these devices does not pose health risks to users. The safety of exposure to electromagnetic fields is a key issue in the certification landscape of electronic products, and it has attracted considerable regulatory and scientific attention internationally.

What are SAR values?

As is known, modern telecommunications are based on transmission of information through high-frequency electromagnetic fields, operating in the frequency bands between 450 and 2700 MHz. Unlike other forms of radiation, these electromagnetic waves fall into the category of non-ionizing radiation, characterized by the inability to break chemical bonds in biological tissues with which they come into contact.

However, when using a device, the portion of the human body closest to the antenna partially absorbs the energy associated with these electromagnetic fields. It is precisely this energy absorption dynamics that is quantified by the SAR values, an acronym that stands for Specific Absorption Rate, or specific absorption rate.

SAR values therefore measure the amount of radio frequency energy absorbed by the human body, expressed in Watts per kilogram of body mass (W/kg). This parameter represents a critical element in evaluating the biological compatibility of devices and is the primary reference for compliance checks with international regulations on user protection.

The methodology for measuring SAR values

SAR values are determined using standardized procedures that simulate real-world device usage conditions, using advanced measurement methodologies. These procedures measure the percentage of electromagnetic energy actually absorbed by the human body during exposure, allowing verification that absorption levels remain within the safety limits established by current regulations.

During measurements – rely on a laboratory qualified as Sicom Testing – Specialized equipment is used, the use of which is strictly codified. Generally, the device being tested is positioned, using a robotic arm, in relation to special tanks whose shape faithfully reproduces the anatomical characteristics of the human head and body. These tanks contain a special dielectric liquid capable of simulating the properties of human biological tissue. A highly sensitive electric field probe then detects the values at various measurement points, allowing the areas of maximum energy absorption to be identified.

The device is tested in multiple configurations that reflect the main real operational scenarios: in contact with the ear, if it is necessary to simulate telephone conversations, or in contact with different body areas when the device is carried on the person.

It is important to underline that the defined values arise from a multiplicity of test cycles and represent the highest absorption levels detected when the device is operating at its highest possible transmission power settings. This gives the certified SAR value a precautionary measure, ensuring a significant safety margin in real-world use.

International regulatory limits

Scientific research has led international regulatory authorities to adopt a precautionary approach in establishing maximum SAR limits for devices placed on the market. As is well known, the European Union has introduced specific requirements relating to exposure limits, subsequently revised to incorporate more rigorous testing criteria. Reference texts include the European Council Recommendation 1999/519/EC, the EN 50360 standard issued by CENELEC (European Committee for Electrotechnical Standardization) and the Directive 2013/35/EU.

Within this regulatory framework, the International Commission on Non-Ionizing Radiation Protection (ICNIRP) has set the maximum permissible limit at 2 W/kg, measured on a 10-gram volume of tissue. This value has been adopted by European legislation and represents the reference for certifying devices on the European Union market. In addition to this parameter, European legislation also establishes a limit of 4 W/kg for the lower and upper limbs, also measured on 10 grams of tissue.

In the United States, the regulatory approach taken by the Federal Communications Commission (FCC) is significantly different. The American government agency has set the maximum limit for SAR values at 1.6 W/kg, measured however on a tissue volume of 1 gram. This methodological difference in measurement means that the values certified according to the US standard are not directly comparable with the European ones, even though both are the expression of strictly defined precautionary criteria.

How to check the SAR values of a device

For those who need detailed information on the SAR values of a specific device, several sources are available. The primary source of information remains the technical documentation provided by the manufacturer, where SAR values are typically reported. This information is mandatory in the instruction manual and, in most cases, also in the public data sheet available on the manufacturer's official website.

At the international level, the Bundesamt für Strahlenschutz (BfS), the German federal agency responsible for radiation protection, operates a public register and continuously updated, containing certified SAR values for a wide range of mobile devices. This database is a fundamental resource for comparing different devices and for searching for certified data.

Furthermore, to ensure effective transparency for consumers and facilitate access to information on compliance with current regulations, the SAR-Tick label has been introduced. This appears as a green mark placed within the technical documentation of each device sold.

The SAR-Tick label represents an attestation of the device's compliance with the maximum exposure limits established by applicable national and international regulations. This marking allows users to easily identify compliance with safety standards, with the assurance that the certified values have been determined according to standardized and shared procedures.

The relationship between electromagnetic fields and human health

The assessment of health risks related to exposure to electromagnetic fields is an extremely complex and still under study area of research.

As previously mentioned, the electromagnetic fields used in telecommunications—unlike ionizing radiation—are not capable of directly altering the chemical composition of biological tissues. Nevertheless, the theoretical possibility of biological effects, understood as short- or long-term functional changes in organisms, remains.

Regarding short-term effects, the World Health Organization has stated that, based on current research, there is no clear causal correlation between exposure and alterations in the body's vital functions.

Regarding long-term effects, the currently available epidemiological literature has not established a direct causal relationship between exposure to electromagnetic fields emitted by mobile devices and the onset of cancer. The International Agency for Research on Cancer (IARC), however, has classified exposure to electromagnetic fields as Category 2B, dedicated to the factors in which a causal relationship is plausible but not yet definitively proven, and where it is not possible to exclude with certainty the role of confounders.

Exposure reduction measures

While scientific research and compliance with regulatory limits provide significant assurances about the safety of compliant mobile devices, precautionary considerations may be valuable. The World Health Organization recommends the implementation of some practices that allow you to reduce the intensity of exposure to electromagnetic fields.

Among the suggested measures is the use of earphones, headphones or hands-free systems During prolonged telephone conversations, maintain a distance between the device and the user's head. It's worth noting that wireless connectivity systems such as Bluetooth headphones operate at transmitted power levels 10 to 400 times lower than cell phones, thus representing a significantly lower-exposure alternative.

It is also recommended to prefer data transmission via Wi-Fi connections rather than mobile networks, and to avoid simultaneously making voice calls and using mobile data. When the reception signal is weak or during movements that require searching for alternative towers, mobile devices automatically increase transmission power, resulting in increased exposure; therefore, such situations should be avoided during prolonged use of the device.

Finally, it is recommended to maintain a physical separation between the device and the body when the latter is carried on the person, for example by keeping the phone in a bag or jacket rather than in direct contact with clothing next to the skin.

The role of specialized laboratories in SAR compliance

Certified compliance with international standards, verified using standardized methodologies, ensures that devices placed on the market meet the most stringent safety criteria.

Determining SAR values and verifying compliance with regulatory limits are obligations that require high technical skills and the use of specialized instrumentation.

Sicom Testing, a specialized laboratory for the testing and certification of electrical, electronic and radio products, offers Comprehensive human exposure assessment services for electrical and electronic equipment, including tests and measurements of SAR values according to current international regulations.

The services offered by our laboratory include planning and executing tests compliant with the latest standards, collecting and analyzing exposure data, and preparing the documentation required for product certification and marketing in regulated markets. This expertise is a critical element in the development and commercialization process of new devices, ensuring full compliance with applicable regulatory requirements in different geographical contexts.

Discover the Sicom Testing human exposure assessment services.