What's the plural form of phosphorus poisoning? Here's the word you're looking for.
Answer
The noun phosphorus poisoning can be countable or uncountable.
In more general, commonly used, contexts, the plural form will also be phosphorus poisoning.
However, in more specific contexts, the plural form can also be phosphorus poisonings e.g. in reference to various types of phosphorus poisonings
or a collection of phosphorus poisonings.