Betreff: [Masts] powerwatch take on Essex [ Essex Provocation Study finds no effect ]
Datum: Wed, 25 Jul 2007 13:03:47 +0100
The latest double blind provocation study by Essex University has found that
there is no significant difference between the subjective (self-assessed
symptoms) and objective (measured symptoms - e.g heart rate) responses
between sensitive and control participants, regardless of the system to
which they were exposed.
Firstly, of the original 56 selected to take part in the study, 12 withdrew
before the double-blind exposures, of which some withdrew very specifically
because of the severity of symptoms from the open exposure. To lose 20% of
the "sensitive" category in this way may well remove the most sensitive, or
"truly" sensitive participants in the study.
Secondly, when addressing a subject such as this, where there is so much
general public concern, there is bound to be a high level of nocebo effect
amongst those that believe they may have a problem. This would give rise to
a much higher proportion of self-assessed sensitive participants that were
not in fact sensitive, and this would have the effect of "hiding" those that
were actually responding to the provocations. This is a potentially very
serious confounder that has simply not been addressed in this study.
Thirdly, anecdotal reports of sensitivity (useful when deciding how an
experiment must be designed) show that many of the effects experienced only
manifest themselves a few hours after exposure, and have often not fully
subsided until the following day. This also seems to vary from person to
person, but it is hard to evaluate what the reason for this would be. Both
of these points are hard to properly incorporate into the design of the
There is very little the study authors can do about the withdrawals, aside
from comment on the potential damage that they can do to the statistical
resolving power of the data (i.e. the chance that all 12 would be 100%
"sensitive" participants and the chance that all 12 would be 0% "sensitive"
participants would both greatly skew the data). It would be useful perhaps
to keep a record of those withdrawing due to excessive symptoms, to create a
"pool" of people that seem to exhibit highest sensitivity (see next point
Nocebo responders are also very hard to sensibly deal with as a confounder,
due to having no prior knowledge of who they are - this is especially true
when cause is not established and it is a theoretical possibility that all
fall into this category. However, there are certain steps that can be taken
to separate out those with highly successful responses, perhaps with the aim
of adding them to the "highest sensitivity pool" (see point above). This
gives the opportunity to test those that seem to be the most sensitive in a
given study without the possible confounders of nocebo sufferers. This was
not done here, but in fairness to the authors this would require another
round of tests and may not have the required participation from the selected
group (who may not want to go through another round of tests).
The problem of effects experienced after a few hours (but not immediately)
was addressed by the study, which tested for symptoms very shortly after the
end of the exposure and allowed the participants to fill in a questionnaire
to return the following week. However, there is a good argument for it not
being necessary as the sensitive group have reported much higher levels of
perceived symptoms than the control group anyway. This gives reasonable
support to the idea that the authors have designed it in a way that should
find effect if there is one.
There is the added possible confounder that the sensitive group were
suffering from stress responses based on the pressure of believing they
might be exposed, and again this is something that it is not reasonable to
expect the authors to eliminate. However, it is a very important issue in
these double-blind provocation studies that can not be ignored.
The problem of responses not subsiding until the following day has been very
well catered for by the research team, as the tests were separated by a
period of one week in each case.
All in all, the Essex team have carried out one of the best designed and
executed studies to date. They consulted widely during the planning stages
and took notice of a wide variety of sources (including Powerwatch and some
individuals who claim to be electrically sensitive). We were present when
Sir William Stewart opened their testing laboratory. Their laboratory is
well designed and uses non-toxic paints and DC lighting to help eliminate
Whilst there were distinct problems early on in the realism of the exposure
system, by the time the actual provocation tests were performed it was the
best we have seen in an experiment to date, including a well designed
simulation of real network traffic. Measured background EMFs in the lab are
negligible (the rooms were screened to a 60 dB reduction in field strength),
and thus one of the biggest flaws of Rubin's work has been dealt with
As with all double-blind studies, there is no way in which the effects of
chronic exposure can be addressed, so this is not a failing of the study but
another point for consideration with regards to final conclusions.
Following this paper, it is becoming increasingly likely that there is a
significant proportion of self-assessed Electrically Sensitive people whose
response is entirely nocebo - whether induced by fear of harm or other
reasons, the cause is not radiofrequency EMFs.
There are fundamental flaws in the idea of evaluating subjective responses
in a double blind system that simply cannot be avoided regardless of the
care taken on experiment design (such as the potentially large proportion of
nocebo responses). There is also a chance that chronic exposure may give
rise to genuine symptoms whereas acute exposure may not, but that cannot be
addressed by this study.
So whilst it cannot be entirely ruled out that a small minority are truly
sensitive, the proportions of any truly sensitive people are likely to be
far lower than the 3% - 35% that has been quoted.
[View paper abstract]
Also in the news
Korean study finds increased leukaemia risk for those living near an AM
In the largest and most detailed study of AM radio radiation to date, a team
led by Mina Ha of South Korea's Dankook University in South Korea has found
that children living within 2km of an AM transmitter had more than twice the
risk of developing leukaemia, compared to those living more than 20km away.
The study, which included 36 cases of children with leukaemia living within
2km of an AM station, will appear in the August 1 issue of the American
Journal of Epidemiology and is already available on the journal's website.
The abstract reads as follows:
Cancer risks were estimated using conditional logistic regression adjusted
for residential area, socioeconomic status, and community population
density. The odds ratio for all types of leukemia was 2.15 (95% confidence
interval (CI): 1.00, 4.67) among children who resided within 2 km of the
nearest AM radio transmitter as compared with those resided more than 20 km
from it. For total RFR exposure from all transmitters, odds ratios for
lymphocytic leukemia were 1.39 (95% CI: 1.04, 1.86) and 1.59 (95% CI: 1.19,
2.11) for children in the second and third quartiles, respectively, versus
the lowest quartile.
This supports their earlier findings in 2004 and 2003, and the findings of
Italian researchers findings in 2002, and starts to lend some genuine
epidemiological weight to the possibility of increased cancer risk for those
living within a few kilometres from radio transmitters.
When Ha compared cases and controls relative to estimated RF exposures, she
found that the risk was significantly higher for those in the second and
third exposure quartiles, but not in the 25% most exposed children.
Regarding the lack of an association among those who are most exposed to RF,
Ha suggested that it might be due to "decreasing statistical power" or to a
Ha estimates that the electric field at 2km from the AM transmitters ranged
from 1 V/m to 3 V/m.
[Abstract of featured 2007 paper]
[Abstract of previous paper from 2004]
[Abstract of previous paper from 2003]
[Abstract of Italian paper from 2002]
Two more studies find effects on rats from GSM mobile phone radiation
The first of which, from INERIS in France, found a temporary change in brain
activity (specifically, glial evolution, suggesting neuronal damage) from
exposure to 15 minutes of GSM 900 Mhz mobile telephony radiation. This
temporary effect was found to be statistically significant at 2 and 3 days,
and to have disappeared after 6 to 10 days from exposure. This supports an
earlier paper from France in 2004 finding the same effect (abstracts linked
at the bottom of news entry). Whether this effect could pose long term harm
remains to be studied.
The Medical College of Wisconsin in the US has found that rats exposed to
cellular phone emissions (2 x 3 hour periods per day for 18 weeks) exhibited
"a significantly higher incidence of sperm cell death than control group
rats through chi-squared analysis. In addition, abnormal clumping of sperm
cells was present in rats exposed to cellular phone emissions and was not
present in control group rats." The authors conclude that "These results
suggest that carrying cell phones near reproductive organs could negatively
affect male fertility".
[2007 rat brain activity paper]
[Earlier 2004 rat brain activity paper]
[2007 rat sperm motility paper]
New Study from Imperial College finds increased infection risk from Electric
Electrical fields generated by everyday electrical equipment such as
computers, and excess static charge created by many modern materials, could
be bad for your health, says new research published by Imperial scientists.
Keith Jamieson of Imperial's Centre for Environmental Policy, lead author of
the paper, says: "Many of the factors that can cause high electric fields
and increased deposition and contamination are often found in hospital ward
environments and in buildings where incidents of sick building syndrome are
The researchers propose, however, that adopting a number of simple
guidelines in home, office and hospital environments could reduce the size
of electrical fields generated, and therefore reduce the levels of
potentially unhealthy particles deposited on the skin and in the lungs as
well as making surface contamination far easier to remove.
Keith Jamieson explains: "In the case of electrical equipment, particularly
laptops, ensuring they are earthed can often greatly reduce fields. In terms
of the electrostatic charge generated by people themselves, careful
selection of materials and humidity levels can significantly reduce problems
as can balanced bipolar air ionisation. Trying to avoid spending time in
areas where high fields are created, and unplugging electrical equipment
when not in use, are also good options - so there are a number of easy
actions which can already be implemented in the workplace and the home to
help reduce the toxic load our bodies have to deal with and the risk of
illness and infection being transmitted in this way."
[Taken from this Imperial College news summary]
Lloyd Morgan on non-thermal biological effects from EMFs
Lloyd Morgan has raised an excellent point regarding the continuous denial
that there is good evidence for non-thermal effects from Electromagnetic
Radiation as follows:
Don & All,
As we all know the existing "safe reference levels" or "guidelines" are
based on an assumption that there are no non-thermal biological effects from
RF EMFs. Further the ELF effects are based on standards that only provide
protection against induced current flow in the body which is a non-thermal
effect. Both are acute exposure situations. Below roughly 10-100 kHz the
primary bio-effect is induced current flow and above that boundry thermal
effects are predominant. When referring to both it is better to refer to
them as "low-intensity, chronic exposures."
Both approaches are de-facto industry controlled safety (sic) levels.
The lie that there are no low-intensity biological effects from EMFs is
readily exposed when pulsed EMF therapy for bone fracture healing is
discussed. There are millions of people whose bone fractures did not heal
after the requisite time in a cast but did heal after pulsed EMF therapy.
The science literature is thorough and extensive. This literature even
understands the mechanism (i.e., pulsed EMFs stimulate bone cell growth).
Even the particular pulsed EMF field is not some random result. The pulsed
EMFs have been tuned to resonate with biological processes.
Whenever possible this message should be provided to journalists (the few
that are not shills for industry).
Regards to all,
[View as published on EMFacts]