Notice: Localized human exposure limits for radiofrequency fields in the range of 6 GHz to 300 GHz

January 2021

Overview

Health Canada is providing recommendations for localized human exposure limits for radiofrequency electromagnetic fields (EMF) in the range of 6 GHz to 300 GHz. These have been developed at the request of Innovation, Science and Economic Development Canada (ISED) in order to support the establishment of new compliance requirements for wireless devices that will operate in this frequency range.

These localized human exposure limits are recommended in scenarios where wireless devices operating in the 6 GHz to 300 GHz range are held close to the body, such as smartphones and tablets, including some 5G-enabled devices.

Learn more about recommended human exposure limits to radiofrequency EMF.

Purpose

The principal aims of this Notice are to:

Communicate Health Canada's recommendations for localized human exposure limits for radiofrequency EMF in the 6 GHz to 300 GHz range
Outline the methodology and findings of Health Canada's approach for developing these recommendations, which included:
- assessing recently published international guidelines
- undertaking a review of the scientific literature
- conducting numerical and computational modeling

Background

Health Canada's Safety Code 6 sets out recommended limits for human exposure to radiofrequency EMF in the frequency range from 3 kHz to 300 GHz. These limits have been adopted by ISED as the Canadian radiofrequency exposure limits for wireless devices and their associated infrastructure, under the authority of the Radiocommunication Act.

Safety Code 6 provides recommended exposure limit values for:

whole-body average exposure, when the whole body is exposed to radiofrequency EMF (for frequencies up to 300 GHz)
localized exposure, when only part of the body is exposed to radiofrequency EMF (for frequencies up to 6 GHz).

As discussed in its Preface, interpretation of Safety Code 6 may be required by Health Canada scientists in order to address new exposure scenarios in a field where technologies are advancing rapidly.

The current version of Safety Code 6 provides whole-body exposure limits covering the 6 GHz – 300 GHz frequency range. It does not specify limits for localized exposures in this frequency range, as these frequencies have not been previously used in sources (i.e., wireless devices) operated close to the body.

Forthcoming wireless devices using the 6 GHz to 300 GHz frequency range, such as smartphones or tablets, may be operated close to the body. To support the establishment of new compliance requirements for wireless devices that will operate in this frequency range, ISED has requested Health Canada's recommendation on exposure limits above 6 GHz for these scenarios. Health Canada has determined that such exposure scenarios would be better addressed through the application of localized exposure limits.

Health Canada's approach

Health Canada has developed an Executive Summary of its analysis of recommended localized human exposure limits for radiofrequency fields in the frequency range 6 GHz to 300 GHz.

Health Canada reviewed the new radiofrequency exposure guidelines from the International Commission on Non-Ionizing Radiation Protection (ICNIRP) (Guidelines on Limiting Exposure to Electromagnetic Fields (PDF format)), which were published in March 2020. The new ICNIRP Guidelines:

introduce localized human exposure limits above 6 GHz
underwent a public consultation in 2018
considered the scientific literature on health effects of RF-EMF exposures and
identified scientifically-established health effects that can occur at exposure levels above the recommended limits (thermal tissue damage and heat-pain sensation)

To assess the validity of these proposed limits, Health Canada:

undertook a systematic analysis of the relevant scientific literature on health effects of exposures in the 6 GHz to 300 GHz range that included studies investigating thermal and non-thermal effects in humans and animals
considered relevant literature studying the interaction between radiofrequency EMF in the 6 GHz to 300 GHz range and human tissues by means of computational and numerical analyses
undertook a computational dosimetry approach using numerical modeling to assess the rise in temperature in superficial human tissues from exposures to radiofrequency EMF in the 6 GHz to 300 GHz frequency range

Conclusions

For localized exposures to radiofrequency EMF in the 6 GHz to 300 GHz frequency range, Health Canada is in agreement with ICNIRP that two adverse health effects can occur. These are:

heat-pain sensation
thermal tissue damage

Health Canada is also in agreement with ICNIRP regarding the threshold temperature for the occurrence of these effects.

Based on a number of worst-case assumptions built into Health Canada's computational modelling, Health Canada determined that application of the ICNIRP limits is justified with certain modifications in order to address a wider range of exposure scenarios. These modifications would further restrict maximal localized tissue temperature increases to levels which are below the thresholds for heat-pain sensation or thermal tissue damage.

Recommendations

For localized exposures to radiofrequency EMF in the 6 GHz to 300 GHz frequency range, Health Canada's recommendations are as follows:

Table 1: Basic restrictions for local electromagnetic field exposure above 6 GHz up to 300 GHz
Exposure scenario	Exposure duration (t)	Local absorbed energy density [ kJ/m²]	Local absorbed power density [ W/m²]
Controlled Environment	0 sec < t < 360 sec	36 [0.05+0.95(t/360)^0.5]	n/a
Controlled Environment	t ≥ 6 min	n/a	100
Uncontrolled Environment	0 sec < t < 360 sec	7.2 [0.05+0.95(t/360)^0.5]	n/a
Uncontrolled Environment	t ≥ 6 min	n/a	20
Notes: "n/a" signifies "not applicable" and does not need to be taken into account when determining compliance. "t" is time in seconds, and restrictions must be satisfied for all values of t between >0 s and <360 s, regardless of the temporal characteristics of the exposure itself. Local absorbed power density exposures are to be averaged over 6 min. Local absorbed power density is to be averaged over a square 4-cm² surface area of the body. Above 30 GHz, an additional constraint is imposed, such that the spatial peak exposure is restricted to two times that of the 4-cm² restriction. Local absorbed energy density is to be averaged over a square 4-cm² surface area of the body. Above 30 GHz, an additional constraint is imposed, such that the spatial peak exposure is restricted to 72[0.025+0.975(t/360)^0.5] kJ/m² for controlled environment and 14.4[0.025+0.975(t/360)^0.5] kJ/m² for uncontrolled environment exposure. Exposure from any pulse, group of pulses, or subgroup of pulses in a train, as well as from the summation of exposures (including non-pulsed EMFs), delivered in t s, where t is the sum of all periods in which there is non-zero exposure, must not exceed these levels.

Table 2: Reference levels for local electromagnetic field exposure above 6 GHz up to 300 GHz
Exposure scenario	Exposure duration (t)	Local incident energy density [ kJ/m²]	Local incident power density [ W/m²]
Controlled Environment	0 sec < t < 360 sec	275/f_G^0.177 X 0.36[0.05+0.95(t/360)^0.5]	n/a
Controlled Environment	t ≥ 6 min	n/a	275/f_G^0.177
Uncontrolled Environment	0 sec < t < 360 sec	55/f_G^0.177 X 0.36[0.05+0.95(t/360)^0.5]	n/a
Uncontrolled Environment	t ≥ 6 min	n/a	55/f_G^0.177
Notes: "n/a" signifies "not applicable" and does not need to be taken into account when determining compliance. f_G is frequency in GHz; t is time interval in seconds, such that exposure from any pulse, group of pulses, or subgroup of pulses in a train, as well as from the summation of exposures (including non-pulsed EMFs), delivered in t seconds, where t is the sum of all periods in which there is non-zero exposure, must not exceed these levels. Incident energy density is to be calculated over time t. Incident power density is to be averaged over 6 min. For frequencies of >6 GHz to 300 GHz: (a) within the far-field zone, compliance is demonstrated if the incident power density, averaged over a square 4-cm² projected body surface space, does not exceed the above reference level values; plane-wave equivalent incident power density may be substituted for the incident power density; (b) within the radiative near-field zone, compliance is demonstrated if the incident power density, averaged over a square 4-cm² projected body surface space, does not exceed the above reference level values; and (c) within the reactive near-field zone reference levels cannot be used to determine compliance, and so basic restrictions must be assessed. For frequencies of >6 GHz to 300GHz: (a) within the far-field or radiative near-field zone, compliance is demonstrated if the incident energy density, averaged over a square 4-cm² projected body surface space, does not exceed the above reference level values; (b) within the reactive near-field zone, reference levels cannot be used to determine compliance, and so basic restrictions must be assessed. For frequencies of >30 GHz to 300 GHz, the spatial peak incident power density exposure must not exceed twice that of the square 4-cm² restrictions. For frequencies of >30GHz to 300 GHz, the spatial peak incident energy density exposure must not exceed 275/f_G^0.177 X 0.72[0.025+0.975(t/360)^0.5] kJ/m² for controlled environment and 55/f_G^0.177 X 0.72[0.025+0.975(t/360)^0.5] kJ/m² for uncontrolled environment exposure.

The application of these limits will help ensure that Canadians continue to be protected from the occurrence of adverse health effects from radiofrequency EMF exposures.

Next steps

ISED will update its radiofrequency compliance requirements for wireless devices based on these recommended exposure limits.

Health Canada will continue to monitor and analyze all relevant scientific literature related to the health effects of radiofrequency EMF exposure.

If new scientific evidence were to show that exposure to radiofrequency EMF below the levels recommended by Health Canada poses a risk, the Government of Canada would take steps to protect the health of Canadians.

For further information pertaining to this Notice, please contact the Consumer and Clinical Radiation Protection Bureau at hc.ccrpb-pcrpcc.sc@canada.ca.

For additional information about the regulation of wireless communication equipment, please contact Innovation, Science and Economic Development Canada (ISED) at: ic.consultationradiostandards-consultationnormesradio.ic@canada.ca.

Page details

Date modified:: 2021-06-16

Language selection

Search