Effects of personalised exposure on self-rated electromagnetic hypersensitivity and sensibility - A double-blind randomised controlled trial.

BACKGROUND: Previous provocation experiments with persons reporting electromagnetic hypersensitivity (EHS) have been criticised because EHS persons were obliged to travel to study locations (seen as stressful), and that they were unable to select the type of signal they reported reacting to. In our study we used mobile exposure units that allow double-blind exposure conditions with personalised exposure settings (signal type, strength, duration) at home. Our aim was to evaluate whether subjects were able to identify exposure conditions, and to assess if providing feedback on personal test results altered the level of self-reported EHS. METHODS: We used double-blind randomised controlled exposure testing with questionnaires at baseline, immediately before and after testing, and at two and four months post testing. Participants were eligible if they reported sensing either radiofrequency or extremely low frequency fields within minutes of exposure. Participants were visited at home or another location where they felt comfortable to undergo testing. Before double-blind testing, we verified together with participants in an unblinded exposure session that the exposure settings were selected were ones that the participant responded to. Double-blind testing consisted of a series of 10 exposure and sham exposures in random sequence, feedback on test results was provided directly after testing. RESULTS: 42 persons participated, mean age was 55years (range 29-78), 76% were women. During double-blind testing, no participant was able to correctly identify when they were being exposed better than chance. There were no statistically significant differences in the self-reported level of EHS at follow-up compared to baseline, but during follow-up participants reported reduced certainty in reacting within minutes to exposure and reported significantly fewer symptoms compared to baseline. CONCLUSION: Our results suggest that a subgroup of persons exist who profit from participation in a personalised testing procedure.

Electromagnetic hypersensitivity (EHS) in occupational and primary health care: A nation-wide survey among general practitioners, occupational physicians and hygienists in the Netherlands.

Subjects who attribute health complaints to every day levels of non-ionizing electromagnetic fields (EMF) have been referred to as electrohypersensitive (EHS). Previous surveys in Europe showed that 68-75% of general practitioners had ever been consulted on EHS. Given the lack of data on EHS in the Netherlands in the general population and on EHS in occupational settings, we performed a national survey among three professional groups that are likely in the first line of being consulted by EHS individuals. Results show that about one third of occupational hygienists, occupational physicians and general practitioners had ever been consulted by one or more EHS subjects. Many of these professionals considered a causal relationship between EMF and health complaints to some degree plausible, and their approach often included exposure reduction advice. Given the lack of scientific evidence for EHS and how low level EMF exposure could cause reported health complaints and given the finding that the majority of these professionals felt insufficiently informed about EMF and health, targeted information campaigns might assist them in their evidence based dealing with subjects who attribute symptoms to EMF.

Novel exposure units for at-home personalized testing of electromagnetic sensibility.

Previous experimental studies on electromagnetic hypersensitivity have been criticized regarding inflexibility of choice of exposure and of study locations. We developed and tested novel portable exposure units that can generate different output levels of various extremely low frequency magnetic fields (ELF-MF; 50 Hz field plus harmonics) and radiofrequency electromagnetic fields (RF-EMF). Testing was done with a group of healthy volunteers (n = 25 for 5 ELF-MF and n = 25 for 5 RF-EMF signals) to assess if units were indeed able to produce double-blind exposure conditions. Results substantiated that double-blind conditions were met; on average participants scored 50.6% of conditions correct on the ELF-MF, and 50.0% on the RF-EMF unit, which corresponds to guessing probability. No cues as to exposure conditions were reported. We aim to use these units in a future experiment with subjects who wish to test their personal hypothesis of being able to sense or experience when being exposed to EMF. The new units allow for a high degree of flexibility regarding choice of applied electromagnetic signal, output power level and location (at home or another environment of subjects' choosing).

The effects of nutrient enrichment and herbivore abundance on the ability of turf algae to overgrow coral in the Caribbean.

Turf algae are multispecies communities of small marine macrophytes that are becoming a dominant component of coral reef communities around the world. To assess the impact of turf algae on corals, we investigated the effects of increased nutrients (eutrophication) on the interaction between the Caribbean coral Montastraea annularis and turf algae at their growth boundary. We also assessed whether herbivores are capable of reducing the abundance of turf algae at coral-algae boundaries. We found that turf algae cause visible (overgrowth) and invisible negative effects (reduced fitness) on neighbouring corals. Corals can overgrow neighbouring turf algae very slowly (at a rate of 0.12 mm 3 wk(-1)) at ambient nutrient concentrations, but turf algae overgrew corals (at a rate of 0.34 mm 3 wk(-1)) when nutrients were experimentally increased. Exclusion of herbivores had no measurable effect on the rate turf algae overgrew corals. We also used PAM fluorometry (a common approach for measuring of a colony's "fitness") to detect the effects of turf algae on the photophysiology of neighboring corals. Turf algae always reduced the effective photochemical efficiency of neighbouring corals, regardless of nutrient and/or herbivore conditions. The findings that herbivores are not capable of controlling the abundance of turf algae and that nutrient enrichment gives turf algae an overall competitive advantage over corals together have serious implications for the health of Caribbean coral reef systems. At ambient nutrient levels, traditional conservation measures aimed at reversing coral-to-algae phase shifts by reducing algal abundance (i.e., increasing herbivore populations by establishing Marine Protected Areas or tightening fishing regulations) will not necessarily reduce the negative impact of turf algae on local coral communities. Because turf algae have become the most abundant benthic group on Curaçao (and likely elsewhere in the Caribbean), new conservation strategies are required to mitigate their negative impact on coral communities.