Denis Henshaw's Column

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Critique of the latest HPA-RPD report on melatonin and cancer

Summary

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 research level.

Specific issues not discussed or otherwise brought out in the AGNIR Melatonin Report

• 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 ubiquitously-acting antioxidant.
• 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 disruption.
• 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