SLA printers: safety with resin contaminated disposals

I've purchased an Elegoo Mars Pro recently, and I've been watching hundreds of video of all kind of processes, and everyone tells the same: resin is toxic, so you should cure it before throwing it to the trash, otherwise it must be treated as toxic waste.

But I've not been able to find anything with "things that are contaminated with it". For example, if I touch with some paper the resin, I guess that I should let it cure in the sun (like putting it in a plastic box and let it cure, maybe?).

But how about the IPA? How do I treat the rests of IPA contaminated with uncured resin? I don't think leaving something flammable into the sunlight during some hours is the best I can do (maybe I'm wrong and it's totally safe?).

Also, are resins water-washable (like this one from Elegoo) as toxic as the rest? Can I wash them in the faucet, or should I use a plastic recipient with just water and wash them there? What do I do with it once I finish? May I throw it into the bath, or let it cure into the sunlight, or...?

Hope this helps me and some others to treat resin disposals as they should be! Thank you!

• For general handling of a resin printer in your living space, refer to Best way to deal with Resin Printers in your living space – Trish Aug 19 '20 at 22:47
• Partial answer (for pure resin & contaminated material) can be found in Safe way of disposing resin – Trish Aug 19 '20 at 22:49
• Both answers give me more information about the subject and they will be useful for sure (regarding safety, there is never enough information)! Thank you so much! – Unapedra Aug 20 '20 at 6:29

At the moment I am waiting for an MSDS of eSun's Water-Washable resin, but the Eleegoo one is available, and it reads that it is classed as "Aquatic Chronic Class 2" - that's better than the Class 4 which IPA-washing resins have, but it is still not Sewer-safe: Do not allow product to reach sewage system or any water source. However, water is much less of a dangerous base for the waste than IPA, making it easier to handle. This mixture too needs to go to a chemical waste handler or be made inert but the waste also can be concentrated with less danger than IPA using a similar apparatus (cold distilling out water) or even a dedicated waste cookpot/evaporation vat that is exposed to heat - though you clearly should do this in a chemical-grade air filtration unit to mitigate the chance of resin fumes escaping into the atmosphere or your work environment if you heat it more than some. The dissolved resin might not be able to cure anymore as the photoinitiator might be used up during it evaporating.