The difference here is that propylene glycol (mentioned as the food additive in the BBC article) is comparatively nontoxic. The 3 janitors drank ethylene glycol

The difference here is that propylene glycol (mentioned as the food additive in the BBC article) is comparatively nontoxic. The 3 janitors drank ethylene glycol, which is quite poisonous. Confusion between the two has been the cause of several mass poisonings involving medicine manufactured with poor quality controls.