ORIGINAL COMMENT · UNEDITED TEXT
As a qualified scientist that has done a lot of research in this area, it is crucial that head and body resonance is legitimately used in the determination of the safety standards.
The fact that it is not, and that this goes against the obvious science, is very questionable, and I'd say in even stronger terms that it's actually very suspicious.
Some research from Grok 4.7 Extra High references this obvious science:
"Head size sets the radiofrequency dose. Standards and most of the research behind them use one adult size. That misses what decides how much energy is absorbed, and where in the brain it lands.
The head works as an antenna. Size sets the frequency it absorbs most strongly, and which parts of the brain receive that energy. Head size changes greatly from infancy to adulthood, and among people of the same age. The FCC does not measure this. Phones are tested on a single adult head. The environmental limits are tightest where an adult body resonates, and they loosen where the head resonates.
The ARRL RF Safety Committee states it directly. "The adult head, for example is resonant around 400 MHz, while a baby's smaller head resonates near 700 MHz. Body size thus determines the frequency at which most RF energy is absorbed." The same guidance puts a grounded adult body near 35 MHz and an insulated adult near 70 MHz, with further resonances near 1 GHz at the body surface. An adult and a baby are not the same antenna.
Absorption peaks when head size matches the wavelength in tissue. The field inside the skull then forms a standing wave, so some parts of the brain absorb several times more than others. A head about 10 percent smaller peaks about 10 percent higher in frequency.
Circumference is about 35 cm at birth and 54 to 58 cm in adults, a factor of roughly 1.6. Applied to the adult figure, 400 MHz moves to about 640 MHz, beside the ARRL figure of 700 MHz for a baby head. At one age the spread is still several centimeters, about a 10 percent shift, enough to move a peak on or off a band in real use. A small adult and a large child overlap. Age is not a stand-in for head size (Nellhaus, Pediatrics 1968; Rollins, Collins, and Holden, J Pediatr 2010; CDC and WHO growth charts).
Calculated models show the same size dependence, and a second peak a uniform head misses. Kritikos and Schwan (IEEE Trans Biomed Eng 1972) found internal hot spots in a tissue-like sphere, the frequency of strongest heating set by radius. Joines and Spiegel (IEEE Trans Biomed Eng 1974) modeled the skull in layers, skin through brain, at 7 and 10 cm radius, to cover different skull sizes. The layered head has a broad peak near 2.1 GHz. A uniform head of the same size does not. At that peak the field is a standing wave that shifts with frequency. Weil (IEEE Trans Biomed Eng 1975) mapped layered heads from 2 to 12.5 cm radius, and the hot spots move with size. The 400 and 700 MHz resonances and this peak near 2 GHz are different. Both move with head size. One adult size sees neither one.
The FCC tests a phone at the ear on one shell, the SAM phantom required by IEEE 1528 and FCC KDB 865664. It is the 90th-percentile adult male from the 1988 Army survey (Gordon et al., Natick/TR-89/044, 1989), filled with uniform liquid, which misses the layered peak. It is not a child, a small adult, or the spread at one age, and it cannot compare 400 MHz with 700 MHz. SAM was meant as a cautious overestimate for older handsets (Beard et al., IEEE Trans Electromagn Compat 2006). Later work finds designs where an anatomical head, including a child's, exceeds SAM (Lee and Choi, ETRI Journal 2019). Papers disagree on the size of that gap (Gandhi, Lazzi, and Furse 1996; Christ et al. 2010). One shell measures neither side.
Away from the phone, the limits (47 CFR 1.1310; OET Bulletin 65) are strictest from 30 to 300 MHz, at 0.2 mW/cm2. The ARRL states why they loosen above 300 MHz: higher power densities are permitted "based on the concept that the body will not be resonant at those frequencies and will therefore absorb less energy." The head resonances sit in that range. At 700 MHz the limit is f/1500, about 0.47 mW/cm2, more than twice the 30 to 300 MHz limit. A smaller body resonates higher as a whole. The University of Florida newborn model resonates at 240 MHz, with a second peak near 800 MHz, and at resonance the public reference level does not hold the whole-body dose to the basic restriction (Dimbylow, Bolch, and Lee, Phys Med Biol 2010). The same shortfall appears for 1-year and 5-year models (Dimbylow and Bolch 2007).
A study or a limit built on one adult head assigns the wrong frequency, and the wrong place in the brain, to children and to many adults. The effect happens where the energy lands, and those peaks move when head size changes. A certification number is the result for one large adult shell. Research and standards need the resonant frequency and the internal pattern across real head sizes, including people of the same age."