Here is an interesting documentary on the effects of EMF radiation in our environment, if you have a spare hour and a half this is well worth watching and quite frightening. Note they talk about Schumann resonance here, you may know also that Blushield does a whole lot more than just reproduce the Schumann resonance and they are talking about one aspect of the earths magnetic field.
Yes 7.83 Hz does do something but it does only for a limited number of people and in nature there are so many more frequencies than just the predominant 7.83 Hz. We have known this for a long time and taken that into account when designing the Blushield.
I wonder what would happen to the bees if we placed a Blushield in each hive? A test we should be sure to look at in the near future.