A few days ago, the iPhone 12 made headlines in France (and therefore, half the world). The French authorities detected that a few hundred analyzed terminals of that model slightly exceeded the permitted power limit that our body ends up absorbing. Specifically, it barely exceeded the ceiling set specifically for the extremities. This led to the withdrawal of the product from the French market, a measure that was later revoked after Apple, the model's manufacturer, carried out a software update that reduced the levels of the terminal's radio frequency waves. The case generated some alarm and brought to the table the debate about whether the waves emitted by mobile phones can be harmful to health. Well, experts have no doubts about it.
To begin with, and before getting into the subject, it is necessary to talk about the Specific Absorption Rate (SAR), which is nothing other than “the measure that indicates how much power is absorbed per kilogram of human body. when it is exposed to non-ionizing electromagnetic radiation [type of low-energy radiation],” Fernando Las-Heras, professor in the Department of Electrical Engineering at the University of Oviedo, explains to La Vanguardia. Specifically, the bitten apple company's terminal registered 5.74 watts per kilogram (W/kg) for the extremities, when the limit is 4 W/kg.
The question is: can this difference of 1.74 W/kg be translated into harm to people's health? Judge for yourselves. Las-Heras explains that, “based on scientific studies”, the International Commission on Non-Ionizing Radiation Protection (Icnirp) considered a SAR value of 4 W/kg for the entire body (not for the extremities) from which The biological effect of being exposed to an electromagnetic field could become a biological risk (potentially harmful to health). Because? Because body temperature could increase above one degree Celsius, generating thermoregulation problems and, therefore, biological damage.
From that figure, this body established its recommendations for any radio terminal, setting a limit for the entire body of 0.08 W/kg for the general public. “In other words, he lowered the bar up to 50 times,” says Las-Heras. Likewise, he set the ceiling at 2 W/Kg (measured on a mass of 10 grams) for the head and trunk and 4 W/kg for the extremities.
“Much more SAR is admitted when the radiation is received in areas that are not so sensitive, such as the extremities,” argues Las-Heras. "It is not the same to receive it in the eye, which is a very exposed area due to the poor blood supply of the lens - so it dissipates less heat than other tissues - than in an arm."
He understands that, although the iPhone 12 emitted at 5.74 W/kg (something that has already been corrected), it “did not automatically generate biological damage.” However, he continues, "it does enter the safety margin of biological risk," which is why he defends that if a limit is legally established to guarantee safety, as is the case, "this must be met."
And who certifies that a mobile phone emits within the permitted SAR parameters? Two actors come into play here: on the one hand, there are testing laboratories and, on the other, certification entities. The Applus company plays both roles: it has various laboratories and certification teams. In addition, it supervises these SAR tests carried out by other laboratories.
José María Laborda, its technical director of the electronic area, explains that there are four families of tests within radio frequency. The first has to do with electromagnetic compatibility. “That is, there are different devices (mobile phone, computer, headphones...) that emit electromagnetic waves and they all have to coexist with each other. What these tests allow is to corroborate that there are no interferences or anomalous behaviors.”
The second deals with the protection of the electromagnetic spectrum. “In other words, the emission flows through the band that corresponds to it and with the pertinent characteristics. Communication on one band cannot interfere in any way with the adjacent band.”
Interoperability is the third. “Each technology requires a form of communication, with specific signal coding. Verifying that this coding is relevant is what is called interoperability.”
And the last is the part of human exposure to electromagnetic waves. “And this is where SAR measures come in,” says Laborda. In Europe, he says, “if the device in question operates with transmission powers greater than 20 milliwatts and is going to be used less than 20 cm from the person, it must carry out SAR measurement tests.”
How do testing laboratories measure the SAR emitted by a mobile phone? There is a protocol. The first step is to fill a type of mannequin with a liquid that simulates the electromagnetic properties of human tissues. The composition of the fluid varies depending on the tissue to be simulated. “The head is not the same as an arm,” argues Laborda.
You don't have to imagine a standard mannequin (see the graph that accompanies these lines). In reality, it is a mold that is placed horizontally and filled. It is thanks to this horizontal position (otherwise the fluid would spill out) that it is possible to pass under the terminal in all the possible positions in which the user will end up using it while a probe is introduced into the liquid (through the upper part of the mold ) to take measurements of the radiation emitted by the mobile phone.
“At the ends of the mold there are two heads. It is to measure the left and right sides. Because? Because there are terminals that are not completely symmetrical,” explains Laborda, who emphasizes that different ways of picking up the phone are simulated: “The most unfavorable case is sought. If there is a possibility, no matter how remote, of taking the terminal, it is measured.” In the following video (made by the Verkotan testing laboratory) you can see the entire process.
The head and body SAR limit in Europe is 2 W/kg, averaged over 10 grams of tissue. In the US, the Federal Communications Commission requires phones to have a SAR value equal to or less than 1.6 W/kg, measured in 1 gram of human tissue. In the North American country (also in France since 2020) testing on extremities is required. It was precisely in this test where the French authorities detected excess issuance of the iPhone 12.
“The limits set are extremely low,” says Laborda. And she gives an example. “If you put your hand in the sun for 5 minutes, you will notice the heat shortly after. With mobile phones, the generation of heat by radiation is considerably less, complying with regulatory limits. I'm not saying that you can't feel a little in your ear if you've been talking on the phone for an hour, without there being contact between the terminal and your ear, but there is no point of comparison."
He argues that the level of security is enormous and that manufacturers are the first who do not want to waste energy. “They, within the limits of electromagnetic emissions, are the first interested in using the essential energy to be able to have the coverage that allows good communication, which translates into good functionality with convenient energy efficiency, and therefore autonomy” .
“What is clear – he adds – is that the worse the coverage, the greater the radiation power, the more battery consumption and possible higher SAR measurements.”
In fact, he asserts, there are certain voices in the industry that ask for these limits to be relaxed a little. “Emissions under current regulation are far from harming health, so slightly higher limits would allow much less complex technological development, or better operation in low coverage scenarios, for example.”
Even so, he assures that "since the current limits have been proven safe and at the same time do not represent an unbreakable barrier for the industry, there is no intention or plan right now to relax them."
