MeV electrons can kill you.* (well, almost, if you own Iridium stock)*

The hazards of MeV electrons are greatest in the outer radiation belts (L~3-5), though they still exist for LEO orbits and the South Atlantic Anomaly.
MeV electrons penetrate, causing deep dielectric discharges, such as the Telstar 401 satellite loss.
The Geosynchronous orbit uniquely lies on the edge of a steep spatial and spectral gradient. Thus GEO poses a wildly variable MeV electron environment, which is nearly impossible to predict, both in principle and in practice.
Yet of all orbits, this is THE most crowded spot.

MeV electrons can kill you.* (*well, almost, if you own Iridium stock)