Characteristics of the application and its use
Digital Enhanced Cordless Telecommunication (DECT) is primarily used for creating cordless phone systems. DECT phones are commonly used in the home and in the work environment. In recent years this technology has also been used for baby monitors and in remote controls for industrial applications.
The DECT operate at frequencies of several MHz. Exposure from DECT devices can be considered as far field exposure in relation to the local base station and as near field exposure in relation to the portable phone or monitor.
Usually DECT telephone users are less exposed to HF than mobile telephone users. This is because the distance between the base station and the portable device and hence the emitted power to transmit the signal is much smaller in DECT than in mobile telephony.
HF effects on the body and health implications
HF fields, in general, have the ability to penetrate into the body (the higher the frequency, the lower the penetration depth), with the main effect of this being a temperature rise in the exposed tissue. The body can adjust to small temperature increases in the same way as it does when undertaking exercise and performing sporting activities. This is because the human body can regulate its internal temperature. However, above a certain level (referred to as the threshold), HF exposure and the accompanying temperature rise can provoke serious health effects, such as tissue damage (burns) and heatstroke. In the case of exposure to HF from DECT, the level of exposure is significantly below this threshold so that body temperature is not affected.
A large number of studies have been undertaken on both acute and long-term effects from HF exposure, such as from DECT, without showing any conclusive evidence of adverse health effects. Much of this research is inferred from the mobile phone and base station literature, as it refers to a similar exposure.
Among all of this research, the risk of tumors in close proximity to the ear where the phone is held, e.g. brain tumors, has been the focus of numerous epidemiological studies. A few of these epidemiological studies have reported a small increase in risk of some brain tumors for the small group of long-term and heavy mobile phone users (read more). These findings may be explained by reporting biases and weaknesses identified in the studies. Several studies have not reported any increase in brain tumors with mobile phone use. Also, experimental studies on animals and cells have failed to confirm the epidemiological studies, and there is no biophysical mechanism that could explain carcinogenicity at such low exposure levels. In addition, the increased risk observed in some of the epidemiological studies is inconsistent with the stable frequency of occurrence of these tumors in the population. That is an important consideration, given the widespread and significant increase in the use of mobile phones in the general population during the last few decades.
In particular, a considerable amount of research has now been conducted on the relationship between HF fields and outcomes such as headaches, concentration difficulty, sleep quality, cognitive function, cardiovascular effects, etc. To date, this research has not shown any such health effects. The only consistently observed finding is a small effect on brain activity measured by electroencephalography (EEG). The biological implication of these small changes is, however, unclear, and they have not been associated with effects on sleep quality or any other adverse health effects.
The overall evaluation of all the research on HF fields leads to the conclusion that HF exposure below the thermal threshold is unlikely to be associated with adverse health effects.
In general, to avoid health hazards from HF exposure, the temperature rise in the body and in the head must be restricted. Thus, ICNIRP recommends that the absorption of HF energy in the head and body, expressed in terms of the Specific Absorption Rate (SAR) that is related to the temperature rise, should be limited. Distinct SAR values apply for whole-body exposure, as typical of those from DECT base station, and for the head as being most relevant when using the phone itself.
ICNIRP follows up the HF related scientific research and any new information relevant to health. A revision of the current ICNIRP guidelines on HF fields used in conjunction with DECT is underway.