Yes, it is completely safe to dispense solid waste in a portable camping toilet. This is their sole purpose - to provide a convenient and sanitary way to relieve yourself while out in nature or on the road. Depending on the type of portable toilet you choose, there will be some basic maintenance that needs to take place to ensure that the unit remains clean and odor-free. You may have to empty a waste tank from time to time, dispose of waste bags after every use, or maintain the compost of your composting toilet. Overall, any of these types of portable camping toilets are effective and completely safe for both liquid and solid waste.