What could be wrong with a one year old that is having loose white stools?

Biliary system: A liver or bile duct issue can cause pale or white stools. Bile is what colors stool. Medication, infection, or bile duct obstruction could be causes. If your child appears ill or this condition persists, he/she should be evaluated by a physician.

Needs attention: Without knowing all the details, like how long, how the growth has been, other symptoms etc, it's hard to know. It would be best to bring this to the attention of your pediatrician with a visit. Diarrhea is usually but not always, infection, and if the poop really is white, that indicates a possible liver problem.