There was a time when I was consuming a lot of industrial cheese. I developed a rash on my legs... One day I realized the rash was certainly being caused by my cheap cheese habit. I'm certain it was related to the "vegetarian enzymes" used as an industrial substitute for the traditional animal rennet. I stopped buying the cheap cheese, and my rash went away.

https://en.wikipedia.org/wiki/Rennet

Contaminants are a common problem in industrial food manufacturing: citric acid (fungal contaminants), vitamin C (heavy metals), and "enzymes" (?).

I'm glad Italians insist their cheeses be made following the traditional methods.