Which approach involves generating a highly toxic substance as needed instead of storing it?

The approach that involves generating a highly toxic substance as needed rather than storing it is minimizing the use or presence of such substances. This method focuses on reducing the risk associated with toxic substances by limiting the potential for exposure or accidents that could occur from storing these hazardous materials.

By generating the substance on-site only when necessary, companies can control the amount produced, ensuring that there is no excess for long-term storage, which can pose significant safety hazards. This strategy not only helps mitigate risks but also allows for better management of the entire chemical process, as the toxicity is only present at the moment of production and is not lingering in another area.

In contrast, the other approaches do not align with generating toxicity only when needed. Moderate often refers to using less harmful alternatives or reducing amounts, substitute focuses on replacing hazardous materials with safer options, and simplify involves making processes easier to manage without directly addressing the issue of toxicity.