So, I should correct the statement: "It kills all microbes that posses a cell structure that is reasonably fragile and rigid at the same time. This seems to include all bacteria, most protozoa, and most fungi, and likely viri as well."

The virus can not be definitively claimed as it is not easily observed until it has been rendered to a non-viable state for examination under an electron microscope.

While we have not examined all bacteria under all circumstances, in every case that we have observed, the bacteria are destroyed.

While we have not examined all protozoa under all circumstances, in every case that we have observed, the protozoa are destroyed.

While we have not examined all fungi under all circumstances, in every case that we have observed, the fungi are destroyed.

As for the effect on human cells, since the cells of all upper organisms, human cells included, are very flexible, they are not destroyed and do not appear in any way harmed, from my observations and from others. This was a big question when I first started zapping, so I did a number of microscopic observations of human cells that were being zapped on a microscope slide. The was no significant change to the structures of the cells even after being zapped for several hours continuous.

There are, however, some caveats. If there is too much electric signal that is applied over too small of a surface area, some skin burning can be expected.

Also, no one with a pace maker or defibrillator attached should use a zapper or actually any device that applies any electric pulses to the body. While it is not the pulse generator that is the problem, a pacemaker or defibrillator can become confused by the electric pulses and either misfire or just plain fail its function.

Also, it is advised not to place the electrodes near the eyes as the optic nerve might suffer damage. While there has never been any reported case of this, it should be considered a possibility.

There are also some exceptions. Avoid the zappers that output more than 11.5 volts as they have a possibility of producing greater skin burning, nerve injury, and other possible issues.

There has probably been over 1 million zappers sold in the U.S. alone ( if not many more ) and not 1 single death or significant injury has ever been reported.

There was a case of 1 very old pacemaker that failed but the user had previously been warned about possible problems and decided that the benefits were the risk. The pacemaker had to be replaced.

One company reported selling as many as 40 thousand units in a 12 month period last year. Not sure if that is a reliable number. For more expensive top of the line models such as ParaZapper MY series, sales are on the order of a few hundred to possibly 1000 units a year.

Some mode expensive units have sold as many as 1000 to 2000 units a year according to their posted numbers.