@Morrisminor72, my degree is in Electrical Engineering (and physics). I know dis tuff.
Even blood, which has about the lowest resistance of anything human, is still not conductive enough to draw much of a current at the small voltages we’re talking about here. Utterly, totally, completely safe.
The quick, easy-to-understand explanation for everyone: The bugaboo to be worried about is Power. Power is the rate at which energy is expended/consumed, and energy is what messes with tissue, by heating it (or burning, in the extreme). Higher power, higher heating rate. Obviously, if the rate (power) is too high, tissue will heat faster than the body can dissipate it, so damage results eventually (faster with higher power). Sunlight is low-power enough that your body mass can dissipate the heat – but its there, that’s why the sun feels warm.
Take everything explained above, then think about microwave ovens. Higher power ones heat things faster, right?
Now, the standard unit of power in the metric system is the watt. Turns out that with electricity flowing through something that resists it (which is everything except superconductors), the power dissipated in the “thing” from the electricity flowing through it is simply the voltage the “thing” is in contact with, times the current that flows through the “thing”.
At 3 volts, the current that flows between any two points on or in the human body is miniscule. Concomitantly, the power dissipated therefore (voltage x current) is miniscule. So much so, that its inconsequential.
Now, it turns out that if you double the voltage this will also double the current, so the power will increase by a factor of 4! This rule generally holds for most “things”. So, while 3V doesn’t cause any problem, 110V will, being around 37 times the voltage resulting in 37x37=1369 times the power.
This is why household voltage (110V) will fry you, while 3V won’t even register.