Denis Henshaw's Column
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Critique of the latest HPA-RPD report on melatonin and cancer
Some parts of the Report are satisfactory but the melatonin/cancer connection
is not well illustrated considering the large amount of data available. As a
result, the Report is rather un-authoritative when it discusses melatonin and
cancer. There appears to be scientific misunderstanding and confusion in certain
areas and lack of insightful comment. The widely differing concentrations of
melatonin in blood, within cells and in certain organs is not discussed nor the
reasons for its efficacy as an antioxidant and radical scavenger.
The distinction between electric fields (EFs), magnetic fields (MFs) and
electric and magnetic fields (EMFs) is not brought out, especially in relation
to reported effects of melatonin and circadian rhythm disruption in the human
body. The limitations of human volunteer studies involving acute magnetic fields
exposures are only briefly discussed. The body of studies for populations
chronically exposed to neighbourhood EMFs, including some volunteer studies
where exposure was carried out over several days, is not collated in a way which
illustrates the overall trend in melatonin suppression/disruption. Reports of
melatonin disruption and other adverse health effects resulting from
fluctuations in the earth's geomagnetic field are not mentioned.
More should have been said about the use of melatonin in the treatment of
breast cancer. Important work published in the peer-reviewed literature, of core
relevance to EMFs, melatonin and cancer is not cited. While this report contains
some useful reading, most evident is the lack of insightful comment at the
Specific issues not discussed or otherwise brought out in the AGNIR
- A description of the widely differing natural concentrations of
melatonin in cells, tissues and organs in the body, and its multiple actions,
some of which are receptor mediated, making melatonin a broad-spectrum and
- No conclusion drawn from the fact that the body of laboratory-controlled
human volunteer studies of melatonin disruption by magnetic fields, appears to
have been initiated by the results of Wever (1979) whose studies of circadian
rhythm disruption concerned exposure to 2.5 V m-1 electric fields.
- In both animal and human volunteer studies, it is those involving
longer-term (non-acute) exposures to magnetic fields (in some cases in the
presence of electric fields) which have tended to show evidence of melatonin
- Studies of populations chronically exposed to neighbourhood electric and
magnetic fields are consistent in providing evidence of melatonin
suppression/disruption, sometimes involving very low field exposures.
- Dose-response issues relating to EMF exposures.
- The work by Blask et al. (2005), which was published after the AGNIR
Report was compiled, which provides, in an animal model, an explicit
demonstration that the normal physiological concentrations of nocturnal
melatonin in human blood per se suppresses human breast cancer growth.
Please click here (272 KB .pdf) to view the full critique