ChatGPT summarizes it as follows:

When substances remain in storage for a long time, they can become toxic to living organisms for several reasons:

Chemical Reactions: Substances can react with the environment or other substances in the storage area to form toxic by-products.

Contamination: Contaminants can enter the storage area and mix with the substance, making it toxic.

Decay: Some substances can break down over time and produce toxic components.

Exposure to light or heat: Exposure to light or heat can speed up chemical reactions that can produce toxins.

Microbial activity: Microorganisms can develop in stored substances and produce toxic metabolites.

It is therefore important to monitor storage conditions and check substances regularly to prevent the formation of toxic substances.