Directorate-General for Health and Food Safety
4. Can mobile phones or base stations trigger headaches or other health effects?
- 4.1 Have headaches and other symptoms been linked to mobile phones?
- 4.2 Can mobile phones affect the brain?
- 4.3 Have effects from RF fields of mobile phones on reproduction and development been reported?
- 4.4 Are children more vulnerable to possible effects of mobile phones?
4.1 Have headaches and other symptoms been linked to mobile phones?
Mobile phone base station
Some people attribute non-specific health symptoms such as headache, nausea, dizziness, fatigue and skin irritation to their exposure to electromagnetic fields. Such complaints have raised concern that certain individuals may be more sensitive than others to EMF. These self-reported symptoms have been named idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) also called electromagnetic hypersensitivity (EHS). The reported symptoms can sometimes be severe enough to cause serious impairments to a person’s wellbeing. While their health concerns are valid, studies conducted since the previous Opinion (about 15 reviewed) adds weight to the existing body of evidence that exposure to RF does not trigger symptoms, at least in the short-term. While additional observational studies are required to assess whether longer-term exposure could be associated with symptoms, the evidence to date weighs against a causal effect.
For symptoms triggered by short-term exposure to RF fields (measured in minutes to hours), the consistent results from multiple double-blind experiments lead to a strong overall weight of evidence that RF fields do not cause such effects. For symptoms associated with longer-term exposures (days to months), the evidence from observational studies is broadly consistent but has gaps, most notably in terms of the objective monitoring of exposure. Current evidence weighs towards an absence of effects due to RF fields exposure.
Even when a participant’s self-report of exposure to RF is accurate, it is still difficult to differentiate whether any association with symptoms is the result of RF exposure per se or whether the association is the result of a ‘nocebo’ effect (a negative placebo effect), whereby the participant’s belief that they are being exposed is sufficient to trigger their symptoms.
Subjects who know they are exposed to some RF fields, e.g. because they use a mobile phone or live near a transmission tower, tend to report more symptoms, whereas double-blind provocations studies where subjects do not know whether they are exposed to RF fields or not do not find a consistent link between radio frequency fields and symptoms.
Actually, there is no scientific evidence that humans - either so-called sensitive groups or healthy control groups - can perceive radio frequency fields better than would be expected by chance.
4.2 Can mobile phones affect the brain?
Because mobile phones come in contact with the head, there have been concerns they could affect the brain.
Studies on possible effects of RF exposure on brain function in humans (such as sleep, cognition, blood flow and oxygenation changes) have given mixed results. The conducted studies are difficult to compare with one another, and so the observed effects were not sufficiently replicated. There are some studies indicating that effects might vary with age and gender; it is not known whether subjects with pre-existing medical conditions may be affected differently. Most of the recent studies have confirmed an effect of RF exposure on electro encephalograms (EEG). There have also been effects found on sleep EEGs but there is not yet any conclusive evidence. Several of the recent studies addressing RF effects on spatial learning, memory, and behaviour suggest an effect at low field levels but there remain significant questions regarding the experimental protocols. No conclusive evidence can be drawn at present.
Experimentally, a number of different end-points have been studied in both mice and rats. Globally these observations are inconsistent and appear mostly at levels well above guidelines values. One of those endpoints is the potential impairment of the blood-brain barrier. Recent studies do not show that exposure to RF has any effect, several of the studies are done in such a way that their relevance for risk assessment is questionable.
Overall, regarding neurological disorders and cognitive functions, locomotion or an increased risk of Alzheimer's, there is no evidence that RF exposure from mobile phone use have a health-relevant effect.
4.3 Have effects from RF fields of mobile phones on reproduction and development been reported?
Numerous large and well-conducted studies have investigated potential effects of RF fields on development of animals, including mammals and birds and clearly show that RF fields can cause birth defects when the exposure is well above safety guidelines and therefore high enough to significantly raise temperatures in tissue. No consistent evidence of effects has been found at exposure levels that do not cause relevant heating of tissues.
No significant effects were seen from almost continuous, lifetime exposure of mice over four generations. More recent epidemiological studies have not shown increased risks of neurological disease or reproductive effect related to RF exposure; effects on foetuses from mothers’ mobile phone use during pregnancy are judged not plausible due to the low level of exposure. The data available provide no clear evidence of consistent adverse effects on human semen quality.
The previous SCENIHR Opinion (2009) concluded that there were no adverse effects on reproduction and development from RF fields at non-thermal exposure levels. The inclusion of more recent human and animal data does not change this assessment.
There are still no substantiated indications of any other health effects.
4.4 Are children more vulnerable to possible effects of mobile phones?
With so many children using mobile phones, there is concern about how radio signals may affect them. Some people worry that children could be more vulnerable than adults because their nervous systems are still developing, their brain tissue is more conductive, their heads might absorb more energy from mobile phones and children using mobile phones will have a greater lifetime exposure than people who were adults when they began using them. Children can also be exposed through other sources, such as baby monitors. Few studies have addressed the possible effects of radio signals on children, and extrapolating from adult studies remains problematic. Overall, current evidence does not demonstrate that children might be more vulnerable to RF EMF, However, age can play a role in the local SAR within the brain, due to the different head size, as well as in specific tissues, (e.g., bone marrow in the skull), due to age-related differences in their dielectric properties.