The way scientists measure radiation is by a unit called a curie. The curie is a traditional unit of radioactivity equal to the radioactivity of 1 gram of pure radium. The curie is named after Pierre and Marie Curie, who discovered radium in their Paris laboratory. Radiation causes cell damage, cancer, aging effects, genome damage, etc. These would be long term risks and would not show up immediately.
Radiation is a big topic in itself.
Toxic effects would be from heavy metal poisoning. Uranium is a heavy metal. Other substances with the ore like lead and arsenic are also present. These can cause kidney damage, nerve damage. A direct toxic effects with chronic stress to the body.