## 3 Results  
### ICNIRP Guidelines  
Coinciding with the development of 5G with its projected use of mmW, the ICNIRP guidelines were updated and published in 2020 [2]. They take a frequency-based approach to assessing exposures. For frequencies < 6 GHz, the basic restrictions use specific absorption rate (SAR), as previously, but add specific absorption (SA) to ensure that the cumulative energy absorbed over 6 min is not so rapid that it could result in \"operational adverse health effects\" (p. 493), meaning heat damage. Both consider mass, using W/kg and J/kg, respectively.  
The updated ICNIRP guidelines remove the use of SAR and SA for exposures > 6 GHz since they claim, \"above about 6 GHz this heating occurs predominantly within the skin\" [5]. As a result, the basic restrictions for >6 GHz to 300 GHz exposure are to be assessed with absorbed power density (ICNIRP S\({}_{\text{ab}}\)), measured in W/m\({}^{2}\), thus limiting assessment to measuring power absorbed by a surface. However, S\({}_{\text{(ab)}}\) measurements are likely to be unreliable in the near field, as explained by [PERSON] et al. [6].  
For exposures > 6 GHz, to prevent overly rapid temperature rise, the ICNIRP specify measuring local absorbed energy density (U\({}_{\text{ab}}\)), also a surface measurement (J/m\({}^{2}\)). In both cases, any internal heating from absorbed energy is ignored.  
This is of concern because previous studies have demonstrated that mmW exposures can result in extremely high SAR readings even when the surface measures such as J/m\({}^{2}\) are acceptably low [7]. The shallower the absorption of energy, the higher the risk of unacceptably high surface heating.  
The updated guidelines have also introduced two categories of tissue, being those that are commonly cooler than core temperature and those that are not. Skin is included in the former category. The calculations and allowances for skin exposures assume that skin (and various other body parts) can safely be heated by 5 \({}^{\circ}\)C based on the normothermal [sic] skin temperature averaging < 33-36 \({}^{\circ}\)C; this is with the goal of keeping skin temperature rise below 41 \({}^{\circ}\)C, at which point tissue damage can occur, p. 489 [2]. Problems for those suffering fever or other temperature control health problems are claimed to be precludedby the safety margin imposed over the level at which \(\geq\)41 \({}^{\circ}\)C would occur [2] (p. 492). It needs to be borne in mind that skin modelling studies treat the skin as homogeneous dermal tissue although it is a complex organ interacting with the environment through nerve endings almost at the surface and blood vessels very near the surface. Further, the induced temperature increase can be underestimated by more than a factor of three [8].  
Declared confidence in the safety of the 2020 ICNIRP approach led to Australia's standards committee removing the precautionary clause from their new exposure standard (RPS-S1 (Rev.1)), saying it is unnecessary [9]. This is despite ICNIRP guidelines [2] and Dr [PERSON] of the Australian Radiation Protection and Nuclear Safety Agency (ARPANSA) acknowledging that higher frequencies can transport heat deep within the body [9].  
ARPANSA is the government body whose responsibility it is to provide advice and services on radiation protection to Australians. This aspect of their purview is led by Dr [PERSON], who is also a main commissioner with ICNIRP.