Status of Human-Made Radioactive Materials in a Biophysical Constrained World.

The discovery of nuclear fission nearly a century ago not only caused the production of significant quantities of radioactive materials, but also purposefully brought naturally occurring radioactive substances from the Earth's crust to the surface through mining. The use of these materials, particularly in nuclear weapons, has profoundly influenced our understanding of the Earth system, driven by the military's need to study the effects of nuclear explosions. This introduced the alarming possibility of irreversible, severe consequences on a global scale within a very short time frame. Despite their critical significance, radioactive materials are scarcely addressed within the Planetary Boundaries framework. This oversight may stem from the challenge of defining control variables or safe operating spaces for the two most consequential release pathways: nuclear power plant accidents and nuclear explosions. Applying the precautionary principle in this context would advocate for a world free of nuclear weapons and a cautious, well-considered approach to the use of nuclear energy.