How much contaminated food do you have to eat to realisitcally risk botulinum?

I had forgotten a stew in my fridge for months. Because I'm an idiot, I dipped a fingertip in it to try it. Only later I found out there is a pretty good risk for some really nasty bacteria in doing stuff like that. Does anyone know how much exaclty you need ot eat to risk a botulinum or similarly dangerous... show more I had forgotten a stew in my fridge for months. Because I'm an idiot, I dipped a fingertip in it to try it. Only later I found out there is a pretty good risk for some really nasty bacteria in doing stuff like that. Does anyone know how much exaclty you need ot eat to risk a botulinum or similarly dangerous illness?
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