# How to make dichloromethane human-friendly and safe for storage?

I use dichloromethane to polish 3D printed object as postprocessing step. Most of it is stored in darkened glass on my balcony (now at $\pu{-15^\circ C}$).

What chemical reactions I need to make it human-friendly (non toxic)? Is it ok to use non-darkened polypropylene/polyethylene box to store it?

What I can do during the summer season? (Dichloromethane is volatile liquid)

• Dichloromethane is a suspected carcinogen. The way to not make it a carcinogen is to make it something else, but then it's not dichloromethane. Storing in a closed bottle where it could be exposed to direct sunlight seems like a terrible idea. – Zhe Feb 23 '18 at 15:06
• DCM might be suspected of being a carcinogen, but it has been tested a lot a there is no evidence it is carcinogenic in people. It is actually one of the safest solvents (it isn't flammable or very toxic.) But it might need to be stored in glass or appropriate metal containers. It is destroys a lot of plastics. – matt_black Feb 23 '18 at 15:46
• @matt_black Here is just a small section of the hazards of DCM: ''Warning!: Causes eye and skin irritation. Causes respiratory tract irritation. Harmful if swallowed. May be harmful if inhaled. May cause central nervous system effects. Methylene chloride is metabolically converted to carbon monoxide after systemic absorption, which yields increased concentrations of carboxyhemoglobin in the blood. May cause kidney damage.'' Therefore i wouldnt say DCM is "safe" in general. Of course it also depends on what your idea of safe is as well. I am talking from a synthetic chemist's perspective. – AMM Feb 23 '18 at 16:07
• @AMM I used to use it a lot in the lab. It was one of the more benign solvents I used. The biggest immediate danger of large quantities was asphyxiation caused from the vapour displacing air (which has happened in industrial reactors). – matt_black Feb 23 '18 at 16:55

According to A Comprehensive Guide to the Hazardous Properties of Chemical Substances at pages 445-446:

Disposal/Destruction

...

Small amounts may be destroyed in the laboratory by hydrolyzing with ethanolic solution of potassium hydroxide

As in Zhe's comment, you cant make DCM human friendly and you shouldn't be handling it recklessly.

DCM, should be used in a fume hood to avoid breathing the vapors and should be stored in amber winchester bottles in a dark and cold place. It dissolves most polymers, so don't try to store it in a PP or a PE bottle as it will eat through it eventually and also get contaminated.

Lastly, if you want to dispose of it you shouldn't just bin it somewhere. Take it in a lab and they will do it properly. Reading the MSD of DCM would also be a good idea.