There are quite a large number of recent studies, Roger. I will try to find some
references. The most recent series has shown that very small changes in the
ambient magnetic field can have strong effects on the rate of certain biochemical
reactions involving enzymes. These rates increase or decrease in a slightly
changed magnetic field by orders of magnitude in some reactions. Science
News has reported on several of these studies over the past several months.
In some cases the increased activity has been associated with chemical reactions
which may be precursory to cancerous conditions, which is the main cause of
interest.