you are right, but i was tought that you have to avoid every risk
Mask, gloves and glasses are essential!
To buy the wrong mask means, to build up a higher rist than without mask. The wrong filter accumulates (adsorb) the MDI or other stuff and gives it free (desorb) when a certain concentration is reached. After that point, you are inhailing more MDI or other stuff!
The right filter with the right active coal adsorbs all MDI and does not desorb it that easy...only if you extend the filters live!
And yes, MDI is carcinogen level IV which means, that it is potential. But this means a higher risk than other chemicals. The point for level IV is, that you cant proove it that easyly. For example, you are casting resin for years and you are a smoker. You cant prove which is the source, because both take long time to take hold!
And yes, as a hobbiist who is casting in a good aired room, you can only use glasses and gloves. But you need fresh air as you need it for priming your stuff with a spray marker!