In my opinion commercial fabric softeners would have to be one of the most toxic and unnecessary cleaning/laundry items found on the supermarket shelf today.
Fabric Softeners work by coating the surface of the cloth fibers with a thin layer of chemicals. These chemicals make the fibers feel smoother and prevent build up of static electricity, that "clean fresh smell" is also a nasty chemical usually labelled as fragrance.  Most of these chemicals have been linked to allergies, asthma, brain damage and cancer just to name a few. These chemicals stay in your clothes and are abosrbed by your skin. Children are most vulnerable as their immune systems are still developing and are not equipped for the huge onslaught of chemicals they are exposed to every day in our modern society. 

The best fabric softener you an use is VINEGAR. It is readily available, cheap and yes it really does work!! If you need a fresh clean smell simply add a few drops of essential oil into your fabric softener dispenser or rinse cycle along with the vinegar.
Alternatively if you have a bottle of Clean Conscience window cleaner handy use that, the main ingredient is vinegar and it has a lovely fresh peppermint smell.

Clean Conscience laundry powder is made with soap nuts and will leave your laundry naturally soft, eliminating any need for fabric softener.