You must be very careful if you are planning to sand the floor of your shipping container. The sanding will release these fumigants and exposure could be lethal. Chemicals such as ethylene dibromide, phosphine, formaldehyde, hydrogen cyanide, methyl bromide, ethylene oxide, sulfuryl fluoride and chloropicrin (trichloronitromethane).

After a couple of years these chemicals dissipate, and you can significantly reduce your risk with special prepping and sealing methods.