Good grief---do you stay up nites thinking of these knit picky things to worry about?? The zapper's current has, just once possibly interfered with an old faulty pacemaker, that would have been more bothered by something like a microwave, by all accounts. The zapper wasn't blamed in this incidence at all, not even by the pace maker company, from what I've read.
And really, do you ask these questions standing by your microwave?? (you should---this is far more something to worry about) If you're so knit picking worried about a mean old evil zapper hurting your princess self, Dr. Clark even tells you how to build one with schematics and stuff starting on page 23 in her book 'Cure for All Diseases'. It's Greek to me, but since you're so worried about such inane things, I'm sure you will be able to find info about whatever's worrying your dear little princess heart. Go read it there.
Dr. Clark says this about it.:
"The most important question, of course, is whether there is a harmful effect on you. I have seen no effects on blood pressure, mental alertness, or body temperatures. It has never produced pain, although it has often stopped pain instantly. This does not prove its safety. Even knowing that the voltage comes from a small 9 volt battery does not prove safety, although it is reassuring... ...Your safety lies in the
short period of exposure that is necessary. Viruses and bacteria disappear in 3 minutes; Tapeworm stages, flukes, roundworms in 5; and mites in 7. One need not go beyond this time, although no bad effects have been seen at any length of treatment.' 'CFAD' page 19-20
And Dr. Clark's zapper isn't about frequencies, as I've said many times, unlike parazapper who seems much more in the Rife camp about this. It's the battery action, the positively offset wave.
"Any positively offset frequency kills all bacteria, viruses and parasites simultaneously
given sufficient voltage (5 to 10 volts), duration (seven minutes), and frequency (anything from 10 Hz to 500,000 Hz)." 'CFAD', page 15
And after 15+ years of at least weekly use, I'm pretty sure it's only benefited me and my immune system, T-cells and all