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Table 2 Characteristics of individual studies. The studies are grouped according to type of exposure or frequency range applied. Details on the results are given for statistically significant results. “No statistically significant effect of exposure” indicates that the development of symptoms was not related to the exposure level (e.g., EMF exposure vs. sham)

From: Methodological limitations in experimental studies on symptom development in individuals with idiopathic environmental intolerance attributed to electromagnetic fields (IEI-EMF) – a systematic review

  Sample (included in analysis) Exposure type Experimental conditions, exposure duration and blinding status Outcome measure Result
VDU
 Andersson et al. [59] 17 IEI-EMF VDU, MF: 245 nT (5 Hz – 2 kHz) and 19 nT (2 kHz – 400 kHz); EF: 7 V/m (5 Hz – 2 kHz) and 10 V/m (2 kHz – 400 kHz) Before and after cognitive behavioural treatment: 1 exposure session and 1 sham session, each 30 min; sessions were separated by at least 1 week;
double-blind study
Global rating of symptoms: assigned score on a 100-mm visual analogue scale (VAS) No statistically significant effect of exposure
 Flodin et al. [60] 15 IEI-EMF Cathode ray tube (VDU or TV), MF: 5–2000 Hz mean of 342 nT, 2–400 kHz mean of 36 nT; EF: 5–2000 Hz mean of 288 V/m, 2–400 kHz mean of 6.2 V/m 2 exposure sessions to the same signal, 2 sham sessions, each up to 1 h; sessions were separated by 2–32 days;
double-blind study
Chosen items from a questionnaire consisting of at least 29 symptoms No statistically significant effect of exposure
 Lonne-Rahm et al. [61] 24 IEI-EMF,
24 controls (12 IEI-EMF and 12 controls
in each of two experiments that where combined for analysis)
VDU, MF: 198 nT (5 Hz – 2 kHz) and 18 nT (2 kHz – 400 kHz); EF: 12 V/m (5 Hz – 2 kHz) and 10 V/m (2 kHz – 400 kHz) 4 different exposure sessions: VDU “on” with stressor (visual test combined with calculations during a limited time period), VDU “off” with stressor, VDU “on” without stressor, VDU “off” without stressor, each 30 min; sessions were separated by 1 week;
double-blind study
Assigned scores on a VAS for rating the severity of facial skin symptoms, stress level, tiredness No statistically significant effect of exposure
 Oftedal et al. [53] 20 IEI-EMF VDU; static EF: − 2 – 9.5 kV/m, ELF EF: 2–12 V/m,
VLF EF: 0.3–10.5 V/m
1 exposure session without filter, 1 exposure session with inactive filter, 1 exposure session with active filter, each session lasted 2 weeks; symptom registration each day in week 2 of each session;
double-blind study
Assigned scores on a 10-interval scale for rating the severity of 7 categories of facial skin symptoms, 1 additional category for “other” symptoms Symptoms less pronounced with active filters, small significant effect for sensations of tingling, itching, pricking (p = 0.03); no statistically significant effect for the 6 other groups of skin symptoms
 Oftedal et al. [62] 38 IEI-EMF VDU; ELF EF: 0–20 V/m,
VLF EF: 0.05–1 V/m
1 exposure session without filter, 1 exposure session with inactive filter, 1 exposure session with active filter, each session lasted 3 months; symptom registration each day in week 4 and in the last week of each session;
double-blind study
Assigned scores on a 10-interval scale for rating the severity of 13 symptoms (skin: 4 symptoms, eye: 5 symptoms, nervous system: 4 symptoms) No statistically significant effect of exposure
 Swanbeck and Bleeker [63] 30 IEI-EMF VDU; static EF: VDU-A: 0.2 kV/m, VDU-B: 30 kV/m; MF (1–300 kHz): VDU-A: 50 nT, VDU-B: 800 nT, alternating EF: both VDUs about 60 V/m 1 exposure session with VDU-A, 1 exposure session with VDU-B, each 3 h; sessions were separated by 1 day;
double-blind study
Report of any skin symptoms experienced during a trial No effect of exposure, concluded without statistical analysis
ELF
 Kim et al. [64] 15 IEI-EMF, 16 controls 60 Hz MF, 12.5 μT at the subjects’ head 1 exposure session, 1 sham session, each 31 min; sessions were separated by at least 1 day;
double-blind study
Assigned scores on a 4-point scale [40] for rating the severity of 8 symptoms (throbbing, itching, warmth, fatigue, headache, dizziness, nausea, palpitations) No statistically significant effect of exposure
 McCarty et al. [52] 1 IEI-EMF 60 Hz EF, average field of about 300 V/m around the head, less than 50 kV/m around the body 1 condition with alternating 100 ms “field on”-“field off”-pulses during 100 s, 1 condition with 100 s continuous exposure, 1 sham condition, test 1: “on-off” and the sham condition repeated 10 times; test 2: all conditions repeated 5 times; next trial delayed until subject reported that symptoms had abated;
double-blind study
Verbal report of any symptoms experienced during a trial, questioned in interview Statistically significant more severe symptoms reported in trials during pulsed exposure (p < 0.05), but not during continuous exposure
 Szemersky et al. [65] 49 IEI-EMF, 57 controls 50 Hz MF, exposed arm: 500 μT, other body parts: 1.14 μT 10 exposure trials, 10 sham trials, each 1 min; trials were separated by 30 s;
double-blind study
Assigned scores on a 4-point scale for rating the severity of 15 symptoms (nervous system: 4 symptoms; visceral functions: 3 symptoms; sensations in the exposed hand: 8 symptoms), 1 additional category for “other” symptoms No statistically significant effect of exposure
 Toomingas [66] 1 IEI-EMF 50 Hz MF, 34 or 100 μT Exposure trials at 2 different intensities and for a duration of either 1 or 10 s, sham trials for either 1 or 10 s, each condition repeated 24 times; interval between trials not reported;
single-blind study
Verbal report of any symptoms experienced during a trial No effect of exposure, concluded without statistical analysis
 Trimmel and Schweiger [55] 36 IEI-EMF, 30 controls 50 Hz MF, 1 mT in the head area Each participant took part in 2 of the following sessions: session with EMF + noise, sham session (noise only), control session without noise and without EMF, each 1 h; sessions were separated by 1 h;
double-blind study
Assigned levels in the “Befindlichkeitsskala” questionnaire [67] for rating mood More discomfort during EMF + noise compared to noise alone condition across all participants (p < 0.05). No statistically significant effect for each group analyzed separately
 Wenzel et al. [68] 3 IEI-EMF,
7 controls
50 Hz MF, 96 mT 1st protocol: 25 min “field on”, 25 min “field off”; 2nd protocol: every 5 min “field on” and “field off” for a total duration of 50 min; no interval between conditions;
double-blind study
Verbal report of any symptoms experienced during a trial No effect of exposure, concluded without statistical analysis
RF
 Augner et al. [56] 8 IEI-EMF, 49 controls Environmental, mainly 900 MHz GSM downlink signal, low: 5.2 μW/m2, medium: 153.6 μW/m2, high: 2126.8 μW/m2 Each participant allocated to 1 of 3 exposure scenarios with different combinations of five 50-min sessions with low, medium or high exposure level; interval of 5 min between each session;
double-blind study
Assigned scores on a 5-point scale for rating the severity of 3 items of well-being (good mood, alertness, calmness) from The Multi-Dimensional Well-Being questionnaire (MDBF) [69] Main effects of exposure (all participants): Less psychological arousal (i.e., significantly calmer) with scenarios including high and medium exposure levels (p = 0.042). No statistically significant effects for other factors of well-being (good mood and alertness). No statistically significant interaction between exposure and group of participants (IEI-EMF or controls)
 Barth [70] 1 IEI-EMF Mobile phone (no information about exposure level, only that the mobile phone was switched “on” or “off”) 15 exposure trials, 16 sham trials; exposure duration and interval between trials not indicated;
double-blind study
Verbal report of experiencing any of 4 symptoms during a trial: palpitations, chest pain, vertigo, prickling in the arm No statistically significant effect of exposure
 Eltiti et al. [21] 44 IEI-EMF,
114 controls
GSM 900 MHz, GSM 1800 MHz, UMTS base station signals; combined power flux density of 10 mW/m2 for GSM signal, 10 mW/m2 for UMTS signal 2 exposure sessions to GSM (combined signal of GSM 900 and GSM 1800 frequencies) or UMTS signal and 1 sham session, each 50 min; sessions were separated by at least 1 week;
double-blind study
Assigned scores on a 100-mm VAS for rating the severity of 6 symptoms (anxiety, tension, arousal, relaxation, discomfort, and fatigue); assigned levels on symptom scales consisting of a list of 57 symptoms extracted from the Electromagnetic Hypersensitivity Questionnaire [6] For individuals with IEI-EMF: elevated levels of arousal when exposed to a UMTS signal (p < 0.0025), likely due to a non-balanced design (45% of participants had UMTS exposure in the first of the three sessions): no statistically significant effect when conditions were compared for each session separately; no statistically significant effect for the 6 other items of subjective well-being, nor for symptoms
 Furubayashi et al. [36] 11 IEI-EMF, 43 controls 2.14 GHz WCDMA base station signal with power density of 0.265 W/m2; EF at the subjects’ head: 10 V/m, calculated brain SAR10g peak: 0.0078 W/kg 1 session with continuous exposure, 1 session with intermittent exposure with EMF turned “on” and “off” randomly every 5 min (50% of the time "on"), 1 sham session, 1 noise session, each 30 min; two sessions on 1 day; sessions were separated by at least 2 h;
double-blind study
Assigned level of discomfort on a 5-point scale; assigned scores on a 5-point scale in the Profile of Mood States (POMS) questionnaire [71] for rating the severity of 6 states of mood (tension-anxiety, anger-hostility, depression, vigor, fatigue, confusion) No statistically significant effect of exposure
 Hietanen et al. [57] 20 IEI-EMF Analogue 900 MHz NMT phone (output power: 1 W), digital GSM phone 900 MHz (output power: 0.25 W), digital GSM phone 1800 MHz (output power: 0.125 W); power densities: 2–200 W/m2 3 exposure sessions to different signals, 1 sham session, each 30 min; sessions were separated by at least 60 min;
double-blind study
Verbal report of any symptoms and sensations experienced during a trial Higher number of symptoms was reported for the sham condition than for any of the RF exposures. Statistical significance (p < 0.05) of this effect was explicitly specified only for men.
 Hillert et al. [39] 38 IEI-EMF, 33 controls 884 MHz GSM mobile phone-like signal, head (calculated): SAR10g averaged peak spatial 1.4 W/kg 1 exposure session, 1 sham session, each 3 h; sessions were separated by at least 1 week;
double-blind study
Assigned scores on a 7-point Likert scale for rating the severity of 14 symptoms (headache, fatigue, nausea, vertigo,
difficulties concentrating, feeling low-spirited, temporary vision problems, 5 questions on dermal complaints, stress, heat or pain from the left ear), 1 additional category for “other” symptoms
Headache more commonly reported after RF exposure than after sham (p < 0.001) due to a difference between headache reports during RF and sham in the non-symptom group; no statistically significant effect on increase in percentage reporting headache. No effect of exposure for IEI-EMF participants and no statistically significant effect of exposure for other symptoms.
 Kwon et al. [72] 17 IEI-EMF, 20 controls 1950 MHz WCDMA mobile phone-like signals (output power: 24 dB), head: SAR1g 1.57 W/kg (measured and calculated) 1 exposure session, 1 sham session, each 31 min; sessions were separated by at least 1 day;
double-blind study
Assigned scores on a 4-point scale [40] for rating the severity of 8 symptoms (throbbing, itching, warmth, fatigue, headache, dizziness, nausea, palpitation) No statistically significant effect of exposure
 Nam et al. [73] 18 IEI-EMF, 19 controls 835 MHz CDMA mobile phone (transmission power: 300 mW), SAR1g 1.2 W/kg (according to manufacturer’s information) 1 exposure session, 1 sham session, each 31 min; sessions were separated by at least 1 day;
single-blind study
Assigned scores on a 4-point scale [40] for rating the severity of 9 symptoms (redness, itching, warmth, fatigue, headaches, dizziness, nausea, palpitation, indigestion) No statistically significant effect of exposure
 Nieto-Hernandez et al. [58] 60 IEI-EMF, 60 controls 385.25 MHz continuous wave signal, 385.25 MHz TETRA handset-like signal (pulsing frequency of 16 Hz), output power each 250 mW; close to the antenna SAR10g 1.3 W/kg 2 exposure sessions to different signals, 1 sham session, each 50 min; sessions were separated by at least 1 day;
double-blind study
Assigned scores in the Positive and Negative Affect Schedule (PANAS) questionnaire [74]; assigned scores on an 11-point numerical scale for rating the severity of 8 symptoms (headache; fatigue; dizziness; nausea;
sensations of warmth or burning on skin; skin itching, tingling, stinging or numbness; feeling irritable, anxious or depressed; difficulty concentrating or thinking)
Before correction for multiple comparisons
For TETRA signal: increased difficulty concentrating. For continuous wave signal: increased ratings of headache in all participants (p = 0.004), fatigue showed reduced initial rating (p < 0.0001) and faster increase (p = 0.014) in non-sensitive participants, increased difficulty concentrating (p = 0.037) and reduced sensations of itching in IEI-EMF individuals.
After correction for multiple comparisons
No statistically significant effect of exposure for TETRA signal. For continuous wave signal: reduced sensations of itching in IEI-EMF individuals (p = 0.03)
 Oftedal et al. [22] 17 IEI-EMF 902.4 MHz GSM mobile phone-like signal, maximum output power 23 dBm ( ̴̴0.2 W), head SAR10g peak spatial = 0.8 W/kg Up to 4 exposure sessions and up to 4 sham sessions, each 30 min, sessions were separated by at least 2 days;
double-blind study
Assigned scores on a 100- mm VAS for rating the severity of pain/discomfort in the head and “other” symptoms No statistically significant effect of exposure
 Regel et al. [23] 33 IEI-EMF, 84 controls 2.140 MHz UMTS base station-like signal, 1 V/m (brain SAR10g peak spatial: 45 μW/kg (calculated)) or 10 V/m (brain SAR10g peak spatial: 4500 W/kg (calculated)) 2 exposure sessions to different intensities, 1 sham session, each 45 min; sessions were separated by 1 week;
double-blind study
Scores in the questionnaire on the Current Disposition [75]; scores in the modified Quality-of-Life questionnaire [76] (23 items within 5 subscales: anxiety, somatic symptoms, inadequacy, depression, hostility) No statistically significant effect of exposure
 Rubin et al. [77] 60 IEI-EMF,
60 controls
900 MHz GSM mobile phone, continuous wave signal, SAR 1.4 W/kg (near to the antenna) 2 exposure sessions to different signals, 1 sham session; each 50 min; sessions were separated by at least 1 day;
double-blind study
Assigned scores on a 100-mm VAS for rating the severity of 7 symptoms (headaches; nausea; fatigue; dizziness; skin itching, tingling, or stinging; sensations of warmth or burning on skin; eye pain or dryness) No statistically significant effect of exposure
 Verrender et al. [78] 3 IEI-EMF 902–928 MHz RF signal, average output power: 1 W; power density: 0.3 W/m2 6 exposure sessions and 6 sham sessions, each 30 min; separated by at least 1 h;
double-blind study
Assigned scores on a 100-mm VAS for rating the severity of the most immediate symptom triggered during the open provocation No statistically significant effect of exposure
 Wallace et al. [79] 48 IEI-EMF, 132 controls 420 MHz TETRA base station signal, 10 mW/m2, estimated SAR: 271 μW/kg 1 exposure session, 1 sham session, each 50 min; sessions were separated by at least 1 week;
double-blind study
Assigned scores on a 100- mm VAS for rating the severity of 6 symptoms (anxiety, tension, arousal, relaxation, discomfort, and fatigue); assigned levels on symptom scales consisting of a list of 57 symptoms
extracted from the Electromagnetic Hypersensitivity Questionnaire [6]
No statistically significant effect of exposure
 Wilén et al. [33] 20 IEI-EMF, 20 controls 900 MHz GSM mobile phone-like signal, SAR10g: 0.8 W/kg (calculated) 1 exposure session, 1 sham session, each 30 min; sessions were separated by at least 1 day;
single-blind study
Report of any symptoms experienced during a trial using a follow-up form No statistically significant effect of exposure
Various
 Rea et al. [54] Experiment 1: 100 IEI-EMF;
Experiment 2: 25 IEI-EMF, 25 controls;
Experiment 3: 16 IEI-EMF
MF pulses of various frequencies between 0.1 Hz and 5 MHz, at hand level: 70 nT, at knee level: 350 nT, at floor level: 2900 nT Experiment 1 and 2: 21 exposure trials at different frequencies, 5 sham trials; experiment 3: 1 exposure trial and 5 sham trials on two separate occasions, each 3 min; interval between trials not reported Report of any symptoms experienced during a trial 16 out of 100 participants reported consistent reactions to exposure in all three experiments, but not to sham; no statistical analysis