Re: Power Lines and Magneti

[John Moulder <jmoulder@post.its.mcw.edu>]

> 	"From  the viewpoint of an epidemiologist", the lack of 
> positive genotoxic findings does not imply a lack of involvement 
> in carcinogenesis, through promotion. (In the two-stage theory

But this is not the situation we face on power-frequency fields.  These fields 
have been tested for epigenetic activity; I am aware of a least 16 studies 
that have appeared in the peer-reviewed literature. 

Power-frequency magnetic fields are not promoters of chemically-induced liver 
cancer (2 studies).

They are not promoters of chemically-induced skin cancer (4 studies).

One study reports promotion of chemically-induced breast cancer at 100 microT, 
but studies at 0.3-1.0 and 30,000 microT are negative.

These fields do not inhibit repair of radiation-induced DNA damage (2 studies) 
or enhance cell transformation (1 study)

One study has reported enhancement of genotoxicity at 5000 microT, but two 
studies at 0.12-120 microT showed no effect.

So the laboratory evidence facing an epidemiologist is:
1)  Extensive documentation that the agent is not genotoxic
2)  No evidence for epigenetic activity at field intensities below 100 microT.
3)  Little evidence for epigenetic activity at any field intensities.
4)  No reproducible evidence for any biological effects at field intensities 
below about 200 microT.
5)  No plausible biophysical mechanism of interaction for field intensities 
below 5 microT, and no known mechanisms of interaction below about 500 microT.

And very important for the epidemiology -- No guidance as to the appropriate 
exposure metric.  If power-frequency magnetic fields are involved in cancer it 
could be peak fields, average fields, transients....