Frequently Asked Questions

Frequently Asked Questions

General:

1. Who is doing the research?
2. What are the health concerns related to TETRA?
3. Is anyone else investigating this issue?
4.  Who would benefit from this research?
5. Why are Psychologists involved?
6.  Are we independent?
7.  Why is independence important?
8. Why do we need to do experimental research on the possible health effects of mobile phone and TETRA masts?

Technical:

1. What is being broadcast by our signal?

Participation:

1. What are the aims of the research?
2. What will I be exposed to?
3. Where would I need to travel to if I decide to participate?
4. Will your study prove that I am sensitive to electromagnetic fields?
5. How will you know whether it is your signal that is affecting me and not something else?

General:

1. Who is doing the research?

We are a team of researchers from the Psychology, Computer Science and Electronic Systems Engineering Departments at the University of Essex, who have received funding from the Department of Health (Mobile Telecommunications and Health Research Programme) to investigate whether the electromagnetic fields emitted from TETRA (Terrestrial Trunked Radio) base stations directly affect human health and well-being. The principle investigator is Professor Elaine Fox.

Given the complex nature of this project it was essential to collaborate across a range of disciplines. In a nutshell, what we set out to do in the current study was to expose people to a signal whilst simultaneously measuring physiological, cognitive and subjective indices.

Experts in physics and electronic systems engineering designed our testing facility and the exposure system.
Our biomedical engineer designed and implemented our physiological measures and he will also be directing the analysis of the relevant data once we have finished testing people in October 2008.
A medical doctor is also an important member of our team. His role has been two-fold: to advise on suitable inclusion and exclusion criteria and to advise on any health issues that arise in day-to-day testing to ensure compliance with that criteria.
Experts in experimental and cognitive psychology form the remaining part of the team. The psychologists were responsible for designing and implementing the cognitive tests being used. Their role extends to the day-to-day running of the project and they will be responsible for the data analysis and writing up of research outcomes at the end of the project in December 2008.

More about the team.

2. What are the health concerns related to TETRA?

TETRA is a fairly new communications technology in use by the emergency services across the UK. Since 1997, hundreds of TETRA networks have been deployed across the world, with a considerable number of these being in Europe, and since 2005 TETRA handsets have been used by all police forces in England, Scotland and Wales.

Although the hand sets are only in use by the emergency services, their associated base stations are located in public areas, so if there are any adverse effects on human health from TETRA emissions it is of concern to us all. Currently there are 2,977 single operator TETRA base stations in the UK (Source: Ofcom, April 2008).

Even though the level of exposure from a hand-held device is thousands of times greater than that of a base station, the exposure from a handset is limited to when a person is either speaking or transmitting other information (e.g. a text) while the exposure from a base station is constant. A base station is constantly sending information, and so is continually emitting electromagnetic fields. If TETRA base stations do cause negative health effects then this constitutes a major public health issue, as has already been demonstrated by the large general public and media interest and concern.

Some members of the police force have complained of feeling unwell as a result of using this new technology. In 2002 nearly 200 police officers involved in a TETRA handset pilot scheme in Lancashire and North Yorkshire took time off sick, complaining of migraines, sleeplessness and concentration problems. In spite of these reported problems, relatively little research has been carried out in this area. It is therefore imperative that studies such as ours are carried out in order to ascertain whether the emissions from TETRA base stations do pose a health risk.

We are very pleased that our study is being supported by members of the police, the army, the fire service and paramedics. We urge anyone who feels that they are affected by electromagnetic fields to come forward and take part in this vital piece of research.

Back to Top.

3. Is anyone else investigating this issue?

Currently our study looking specifically at TETRA base station emissions is the only one of its kind being undertaken in the UK, although two studies investigating TETRA handsets are also underway at Imperial College (Airwave Health Monitoring Study) and King’s College London.

It is important to note that the MTHR is currently funding a wide range of projects into electromagnetic fields and health. Click on this link for a list of all the projects that are currently being funded. For more information on other research into electromagnetic fields being carried out across the world, visit the WHO website.

4. Who would benefit from this research?

Our research has two basic aims:

To provide scientifically valid evidence on the effect of TETRA signals on physiological, psychological and health functioning for people who believe they are sensitive to electromagnetic fields and for people who don’t experience any sensitivity.
To provide evidence for the preparation of appropriate advice to be given to the general public on the possible effects of exposure to electromagnetic field emissions from TETRA base stations.

At the moment there is a lack of hard scientific evidence about the effects of TETRA masts on human health and well-being, so whatever the end result of our study, your participation will be highly valuable as it will be contributing to a wider body of research.

5. Why are Psychologists involved?

Psychology is a wide ranging empirical science (very different from what popular psychology books and TV programmes may imply) in which two major areas are health and cognition. Many EHS individuals not only experience physical symptoms, such as headaches or skin rashes, but also complain about short term memory loss and difficulties in concentration. Therefore, psychological and physical factors are always closely integrated and so experimental psychologists are best placed to investigate these issues. The Essex team is a multi-disciplinary team of internationally recognized experts in the fields of experimental psychology (memory and attentional functions in relation to brain processes), biomedical engineering, antenna design and a practising medical practitioner. All of these disciplines play a pivotal role in investigating the complexities of environmentally induced illnesses, such as EHS.

6. Are we independent?

To be considered independent it is vital that the researchers in question are impartial in their approach to the design and execution of their research and in the interpretation of their findings. In addition, independent researchers are not affiliated with or directly funded by commerce or government.

The University of Essex research team was awarded a grant to carry out research into the possible health effects of TETRA base stations by a committee of scientists who are independent of government and industry. This committee assessed many applications from different research teams who responded to a call for applications and the Essex application was judged to be the best. Thus, neither the government nor industry had any influence over how the funds were allocated or how the various research teams on the programme are conducting their research. Importantly, this also means that neither can influence the interpretation or distribution of our findings.

7. Why is independence important?

Independence in research is essential for one very important reason: to ensure valid research results. Validity is not just about how the study is designed and executed. It also concerns interpretation of findings and whether people believe that the study has been conducted in an unbiased way.

Firstly, research of any kind is an investment and therefore should not be influenced by the views or needs of either the researchers themselves or any external sources. Although all researchers follow strict ethical guidelines when conducting research, being independent allows researchers greater freedom in keeping a distance from any one organisation that has a vested interest in the research findings. This is particularly relevant with mobile phone technology research, since the findings from our project and those of other projects currently under way will affect mobile phone companies, government policies, pressure groups and individuals who are either worried that their health might be affected or are sensitive to the electromagnetic fields being emitted from masts and other wireless communication devices. In this sense there are many stakeholders and it is important that we remain independent of all of them in order to conduct valid research.

Secondly, research must be seen by the general public to be valid. Research findings can be undermined by the perception that the research was influenced by a party with a vested interest. For example, a drug company pays for research into one of their products. The study finds that the product is an excellent remedy for a particular type of illness. Even though the research was carried out properly and within ethical guidelines, a rival company may claim that the company in question had a vested interest and the results should not be trusted. They may demand that further testing be done by an independent researcher. Clearly, it is in everybody’s best interests that the research is carried out independently to start with.

In addition to independence, additional measures may be used to ensure that the results are valid. One of the most important measures is to conduct double-blind studies. “Double-blind” means that neither the researcher nor the participant knows what condition the participant will receive. In our current study we are looking at two conditions: SHAM (no signal), and TETRA. When participants go into the testing booth neither ourselves nor the participant know what condition they will be exposed to. Therefore, the researcher cannot influence the way the participant reacts, nor can the participant bias the results by responding in a particular way.

8. Why do we need to do experimental research on the possible health effects of mobile phone and TETRA masts?

Some people view experimental research as being divorced from reality and that any conclusions drawn from experiments therefore cannot be generalised to real life. Epidemiological research and case studies are often considered more valid to study the safety of mobile communication base stations and electromagnetic hypersensitivity, because they allow people to be observed in their own environments. We argue that experimental research certainly does have an important role to play with respect to the investigation of whether or not base stations cause negative health effects and that the results can provide useful information that can be applied in the real world.

Here are some reasons why we chose not to conduct epidemiological research or a series of case studies:

Associations found through epidemiological studies are difficult to interpret because they cannot prove a cause-effect relationship. For example, there may be an event or factor not yet considered that is really to blame. In contrast, experiments are designed to investigate cause-effect relationships in a more direct way.
Case studies provide many details pertaining to the person, group or event under study, but are reliant upon subjective interpretation and explanation. Thus, as with epidemiological research, while these case studies are extremely useful it is difficult to draw any conclusions about cause-effect relationships.
Replicating the findings produced by case studies and epidemiological research is problematic because variables are not well controlled.
A particular problem with epidemiological studies on electromagnetic fields is that they cannot adequately measure how much exposure an individual is or previously has been exposed to. For example, distance from a mast is a poor way of determining exposure as a much stronger mast further away may be contributing more to the background electromagnetic radiation; or if somebody walks by with a mobile handset the amount of radiation will increase far beyond that contributed by the mast. This is why epidemiologists have considered it virtually impossible to conduct good studies in people’s own homes; it is impossible to determine how much exposure each individual receives. When individual exposure meters are available, which people would need to wear for a couple of weeks, then this type of research would be more feasible.

Case studies and epidemiological studies are useful indicators of the factors involved, but they don’t allow us to determine the extent to which electromagnetic fields influence health. This makes the results relatively unreliable.

There is a further, more specific problem which relates to studying base station emissions. The nature of the electromagnetic fields emitted by base stations is highly complex:

The number of mobile phone users is constantly changing, which affects the demands placed on base stations and the power emitted from them.
Technology is constantly changing (e.g. analogue=>GSM=>UMTS).
New services are being added (e.g. TETRA).
Radiation patterns are highly complex and it is important to consider whether measurements are being taken indoors or outdoors.
The spectral composition changes according to the site and time.
Depending on the topography of the area, electromagnetic fields, similar to visible light, can be blocked, reflected, refracted, scattered, and/or diffracted off different types of objects, such as buildings, houses, cars, signs, hills, etc.

Clearly, electromagnetic emissions from base stations in the natural environment change all the time due to a wide range of very complex interdependent factors. Experimental studies are therefore well-placed to provide reliable and accurate information regarding the safety of mobile phone base stations, provided they are well-designed and executed.

Technical:

1. What is being broadcast by our signal?

The signal:

· We are broadcasting a TETRA signal of 420MHz at a power density of 10mW/m2.

· The version in use for this project is Release 1.

· The signal comprises a TDMA (time division multiple access) structure in accordance with the European Telecommunications Standard Institute (ETSI) using a high spec signal generator.

· There are 4 timeslots per frame on a single carrier and the properties of the signal are modelled on the TETRA system which is used by the emergency services.

· The frequency of the signal we are using is very close to the emergency services signal but for obvious reasons is not exactly the same! For example the police TETRA signal operates at around 390MHz.

Waveform:

· There is a marked difference in the waveform depending on whether or not traffic is carried by the transmission due to the presence/absence of frequency correction in the bursts (FCCH).

· Frequency Correction Channel (FCCH) is only present under ‘no traffic’ conditions.

· A ratio of timeslot occupancy of 50:50 was therefore applied to enable an equal balance of the two states for the purposes of the study.

SAR:

· The approximate SAR value for this study is 271µW/kg.

The calculation used is for whole body exposure using the formula:

body surface area x power flux density

body weight

We based our calculation on assumed values of body surface area (BSA) and weight. The SAR value of 271µW/kg is for a person with a BSA of 1.9m² and a body weight of 70kg. Thus,

1.9x10mW

70kg

Participation:

1. What are the aims of the research?

In our particular study we have two very specific research questions:

Are EHS symptoms related to exposure to electromagnetic fields as produced by a TETRA base station signal?
Do electromagnetic field emissions produced by the TETRA base station signal have a direct effect (either positive or negative) on individuals who do not report sensitivity to electromagnetic fields?

2. What will I be exposed to?

You will be exposed to one signal: a standard TETRA signal which will be broadcast at 420MHz. See above to find out more about the signal characteristics. You will also be exposed to a SHAM condition where the base station is off (no signal is produced).

3. Where would I need to travel to if I decide to participate?

You would need to travel to the Electromagnetics and Health Laboratory at the University of Essex in Colchester, Essex.

Back to Top.

4. Will your study prove that I am sensitive to electromagnetic fields?

Our study is not designed to measure sensitivity in individuals. Each person’s data forms part of group statistical analyses. We look to measure differences between conditions (TETRA vs SHAM) and groups (ehs vs control). However, in the individual results we will send you we will be able to tell you whether you correctly judged when the mast was on and when it was off. In addition, during Session 1 you will be told when you are being exposed to TETRA and when you are being exposed to SHAM which will allow you to get a sense of whether this particular signal elicits any negative responses in your health and well-being.

Back to Top.

5. How will you know whether it is your signal that is affecting me and not something else?

We accept that people arrive at our study having had a variable amount of sleep, food intake and so forth. We also appreciate that in addition to the stresses of travel people are unavoidably exposed to ambient electromagnetic fields. Creating an experiment where every variable is controlled for is unfortunately not possible. This is where the importance of research design comes into play. We control for extraneous variables by:

a. having a SHAM (no signal) condition alongside the active (TETRA) condition;
b. having a control group matched in age and gender to the sensitives tested;
c. having a large number of participants;
d. conducting the experiment in a standardised way (i.e. everyone is given the same tests with the same instructions).

A well-conducted study should allow for many different comparisons to be made using a variety of tests that follow a pattern (convergent evidence). For our study, we are looking into physiological responses (heart rate, blood pressure, skin conductance), subjective well-being (symptom questionnaire) and cognitive functioning (memory and attention) - the results should all contribute towards what we are investigating: do TETRA masts have a negative impact on health in the short-term?

REFERENCES:

Leitgeb, N. (2005). Epidemiologic studies on mobile phone base station exposures (presented at the WHO Workshop on Base Stations and Wireless Networks, Geneva, June 2005).

Doll, R. et al (2001). Possible Health Effects From Terrestrial Trunked Radio (TETRA). Report of an Advisory Group on Non-Ionising Radiation. Documents of the NRPB, Vol. 12, No. 2.