Testing commissioned by the Chicago Tribune suggests that Apple's iPhone has radio frequency broadcasts slightly above a legal limit, which has spawned a new range of testing by the federal government but this is not a crisis, nor a health hazard in any way, and here's why.

Cellphone radio frequency testing by the Chicago Tribune has gone on for over a year, according to the publication. The eponymous RF Exposure Lab was selected for the testing, and took one sample from 11 different smartphones, and positioned them between a sensor and a container of fluid with RF absorption properties the same as human flesh.

Tests were performed in accordance to what the manufacturers use for a spec as mandated by the US Federal Communications Commission (FCC). In the case of Apple, that is 5mm from the surface of the skin. An additional test was performed at 2mm, chosen by the third party as an average of pants pocket fabric thickness.

Samsung tests at 10mm and 15mm. Regardless of 5mm, 10mm, or 15mm, the FCC requires that at the point of closest exposure, users cannot absorb more than 1.6 watts per kilogram, averaged over one gram of tissue — this is called the "specific absorption rate" or SAR.

Tests are performed with a probe immersed in tissue simulating fluid. A base station simulator is used, with a tester placing a call to the phone being tested, with settings on the base station adjusted so that everything is on the same band, frequency, and channel. The highest radio frequency radiation is used for the maximum over a range of tests during the regulatory approval process.

In a worst-case scenario, from 5mm away, the probe embedded in the ersatz tissue received 2.64 watts per kilogram during the third-party tests with an iPhone 8. An iPhone 7 delivered 2.81 W/kg, and a different iPhone 7 got a similar result of 2.50 W/kg.

Motorola told the lab that they believed that a proximity sensor hadn't been properly engaged. When the lab followed Motorola's directions, a phone which exceeded the SAR limit by over three times, passed the test at 5mm.

A cellphone is tested at RF Exposure Lab in October 2018. Photo credit Brian Cassella of the Chicago Tribune

Similarly, when an iPhone 8 was grasped, it too was under the limit at 5mm — but the iPhone 7 was not. When pressed for more information on how the initial testing was performed, and how the lab could further improve the testing, Apple wouldn't comment.

"We take seriously any claims on non-compliance with the RF (radiofrequency) exposure standards and will be obtaining and testing the subject phones for compliance with FCC rules," FCC spokesman Neil Grace told the Chicago Tribune following the test report.

Apple took issue with the testing by the newspaper, and issued a statement saying that the tests "were inaccurate due to the test setup not being in accordance with procedures necessary to properly assess the iPhone models."

"All iPhone models, including iPhone 7, are fully certified by the FCC and in every other country where iPhone is sold," Apple said. "After careful review and subsequent validation of all iPhone models tested in the (Tribune) report, we confirmed we are in compliance and meet all applicable exposure guidelines and limits."

Apple refused comment on further questions by the Chicago Tribune.

It isn't clear why the lab wasn't aware of a proximity sensor in an iPhone that at this point is three years old. AppleInsider has emailed the lab asking that, and some other questions, about the testing.

Every cellphone manufacturer in the US has to test devices pre-sale for RF SAR. However, the manufacturer generally gets to choose their own devices.

Apple says that the SAR in the iPhone 7 us 1.19 Watts per kilogram in the head or body. The iPhone 8 has a SAR of 1.20 Watts per kilogram.

Still not a cause for panic

We're not excited about the results of the testing. Independent testing claiming that Apple is under-reporting SAR isn't good for anybody. But this isn't a health crisis, or an actual giant drama regardless of what speculative headlines in the coming days will lead you to believe.

Federal limits for RF exposure to the populace are extremely conservative, and the testing is performed in absolute worst-case conditions. While the levels seen by the testing are above that limit, the iPhone models in question do not pose any imminent safety hazard.

The US government sets several limits on exposure to just about everything. One is a safe limit, a second is an occupational limit, and the third is a non-occupational limit. In the case of radio frequency exposure like from the iPhone the occupational limit for industry workers is 10% of the safe limit, with the non-occupational limit set at 2% of the safe limit.

So, even with the proximity sensor on the iPhone 7 in question disengaged, at worst, the exposure is 3% of the safe limit, according to FCC exposure mandates.

And, like we said before, RF is not ionizing radiation. With RF, beyond thermal effects, there are different alleged mechanisms for damage — which is part of the current controversy surrounding RF.

Proponents of the limits as they stand say that there is no increase in cancers or other observable health effects in the population that is not attributable to better diagnostic methods — which, ironically, use various wavelengths of RF or radiation exposure to find. Opponents claim that the SAR limit isn't sufficient, and fails to incorporate other possible vectors of damage, or lacks sufficient study.

Research on radio frequencies

The US Food and Drug administration is continuing study. In a document detailing research published in May 2019, the agency points out that RF is classified in the International Agency for Research on Cancer's Group 2B and is "possibly carcinogenic to humans."

Other materials classified in the 2B grouping include the metal nickel, ginkgo biloba extract, nearly every food coloring, aloe vera, gas engine exhaust, and pickled vegetables.

The American Cancer Society has also not found a link to RF exposure and leukemia and lymphoma. The group has also pointed out that exposure of single-celled animals to RF is not the same as exposing a complex organism with skin, nor is exposure in mice or other small mammals equivalent to human exposure.

The World Health Organization declares tissue heating the "principal mechanism of interaction between radio frequency energy and the human body" predominantly because of the frequencies used by mobile phones. A study found no increased risk of glioma or meningioma with mobile phone use of more than 10 years, but is advocating for continued study given the prevalence of modern cellphone usage.

Studies will continue until our sun extinguishes, in all likelihood — and they should. But, given the inherent variances of studies involving living creatures, proponents of the existing limits won't change their minds by contrary results, nor will detractors be ameliorated by results confirming existing figures, unless something really dramatic is discovered.

That seems unlikely given that humanity has been generating its own radio frequencies for over a century.

Do the math

This exposure measured by the lab, or any radiative source, is impacted by what is called the inverse square law. Basically, the intensity of an effect like RF or ionizing radiation changes in inverse proportion to the square of the distance from the source.

Without delving into the difference and mathematics involved in considering a line source and a point source, practically, every doubling of distance from the source, cuts the exposure from that source to 25% of what it was at the closer range.

There is no limit for RF at 2mm. And, even if the same limit at 5mm was applied, it would only be approached or possibly exceeded if a call was received, accepted, and actively in progress. There is a difference between a phone pressed up against a leg, and against an ear. While the phone next to the ear is in fact next to your head, it has a big, bony structure between it and the brain — your skull.