Phase 2: Provocation Study

The second and main phase of our study began in January 2004 and was completed in December 2006. The aim of this study was to determine if electromagnetic fields emitted by the two main types of mobile phone base-stations (GSM and 3G) affect a variety of measures of health and well-being. We tested 56 people who suffered from EHS as well as 120 people who did not. In order to be scientifically valid, the study was conducted under “double-blind” conditions. This simply means that neither the person conducting the research, nor the person being tested knew when the base-station was “on” or “off”. Once we had completed the data collection phase (testing all our participants) we were able to “crack the code” and see to what extent the electromagnetic fields affected a variety of symptoms that people had reported, as well as measures of blood pressure and heart-rate. Analysis of the results is now underway. Once the paper has been peer-reviewed and accepted for publication the University of Essex will issue a press release and the research report will be made publicly available. We cannot release any preliminary findings, because our results must first be verified by independent scientists.

Design of Study

The provocation study involved one open provocation session and three double blind sessions, which meant that participants were required to travel to the University of Essex on four separate occasions.

Session 1: Each participant completed an Open Provocation test in which both the researcher and participant knew when the base station was ‘on’ or ‘off’ and if it was ‘on’, whether it was emitting the GSM or UMTS signal. During this time participants completed Visual Analogue Scales and recorded any symptoms that they experienced. Each exposure condition (GSM, UMTS, SHAM) lasted 15 minutes separated by 2 minutes of 'wash out' where nothing happens. At the end they performed the Digit Symbol Substitution task and the Visual Digit Span task. They also completed a quick Double Blind test where neither party knew the exposure condition and participants simply made a judgement as to whether they believed the base station was ‘on’ or ‘off’.

Sessions 2, 3 and 4: These sessions were all Double Blind and were 50 minutes long. This time participants only received one exposure condition per session. During these sessions participants spent 20 minutes watching the ‘Blue Planet’ video and 20 minutes doing Mental Arithmetic. These tasks were interrupted every 5 minutes for participants to complete the Visual Analogue Scales and to record any symptoms that they were experiencing. Participants then completed the Digit Symbol Task, the Visual Digit Span task and made a judgement as to whether the base station was ‘on’ or ‘off’. Participants were then taken back into the reception room where they completed a Pattern Glare test and recorded any symptoms that they may have been experiencing after testing.

Following sessions 2, 3, and 4, each participant completed follow-up questionnaires monitoring his or her symptoms over the following 6 days.

All testing took place in an electrically screened room and the mast, which was out of sight, emitted electromagnetic fields similar to a normal base-station, which is significantly less powerful than the electromagnetic fields emitted by a mobile phone itself. When the base station was on the power output was 10mWm^-2, which is no more than people would experience in an average outdoor environment.

We had two signals:

GSM Signal (mixed 900 and 1800MHz signal):

The transmit system consists of 2 carrier channels per frequency band, one for broadcast and one for traffic.

The broadcast channel transmits information from the base station to the mobile phone and the information it gives is very specific: It tells the mobile phone when it can transmit information and what frequency it needs to transmit that information on (i.e. when the base station is available to receive information and what frequency it can receive it on).

The traffic channel represents the normal activity of somebody who is either making a call or receiving a call on their mobile phone. This includes all the information either voice or data (for example, a text) that is being sent to the mobile phone. It also captures the information needed to dial up, connect and end the call.

The pattern of signals emitting from the traffic channel were modelled on actual base station busy hour call activity.

UMTS (3G) Signal (2100MHz):

The UMTS signal used was one frequency as the UMTS transmit system is more versatile than GSM. UMTS, or 3G, is the next step in the progression of mobile phone technology. UMTS identifies users on the basis of a specific coded sequence rather than using one frequency to downlink (information travelling from a base station to a mobile phone) and another frequency to uplink (mobile phone to a base station). Note that our tests do not simulate the uplink frequency as this is the one travelling from a mobile phone to a base station.

Since UMTS networks are not fully established traffic modelling was developed using the “Test Model 1” method, which is a standard procedure adopted by the mobile phone industry.

Participants were required to travel to the University of Essex on four separate occasions, approximately one week apart. Participants were paid £5 per visit, in addition to covering expenses for travel and food up to £30 per visit.

We are very grateful to all our participants for the enormous contribution they have made to our research.

Key questions that this study addressed were:

1. Do sensitive individuals experience more symptoms and a greater severity of symptoms during real exposure (i.e. GSM and UMTS) compared to sham (no signal)?

2. Does short-term exposure to GSM and UMTS base station signals affect the well-being of people in the general population (our control sample)?

3. Are sensitive individuals able to identify above chance level whether the base station is turned 'on' or 'off'?

4. Is performance on concentration and memory tasks affected by real compared to sham exposure?