The static charge on a human averages around 10 nano amps. This is a problem when it is shunted to ground through a circuit with a current limit that is a small fraction of that amount.
That amount of current is more a tribute to precision electronics that allow us to measure it than anything else.
Note also that the static charge on a human is dependent on the humidity level. Some manufacturing facilities have humidifying misters to help reduce static charge on people.
People who live in damp climates will have much lower static charge levels on the surface of their body. Also, washing your hands will reduce the static charge on the surface of your body.
Lastly, I did find one study done by a Chiropractic University that examined the claim that there is information transferred from the body to the earth. They found that the signal is too weak and too random to possibly contain information.
All the claims for earthing belong in one of these:
