Consumer advocates and environmentalists are outraged that the government resold products it deemed unsafe to live in, saying warning stickers attached to the units will not keep people from misusing them.

Besides formaldehyde, units may be plagued by mold, mildew and propane gas leaks, FEMA acknowledged.

"Proceed with caution, extreme caution, if you are tempted to respond to what appears to be an attractive offer for a travel trailer or manufactured home," Arkansas Attorney General Dustin McDaniel wrote in a consumer alert.