Caustic Powders and Liquids
When swallowed, alkali burns the swallowing passages and sometimes portions of the airway (especially above the vocal cords). This can lead to airway and swallowing passage obstruction and a serious chest infection.
Many household cleaners contain alkali (the opposite of acid). Laundry and dishwasher powders, gels and liquids, hair-straightening products, ammonia capsules (“smelling salts”) and disc batteries must be kept out of reach of young children.[Ref:15][Ref:16]
When small portions of laundry or dishwasher detergent are packaged in individual “capsules” (marshmallow-sized plastic wraps), a capsule (or “pod”) could cause complete airway obstruction (before causing internal burns).[Ref:41]
Over one hundred years ago, Dr. Chevalier Jackson began a decades-long struggle with the U. S. Congress to pass the Federal Caustic Poisoning Labelling Law of 1927. As a result, drain cleaners and many other (but not all) alkali substances have a “skull and crossbones” warning label.
It is not clear if small, symbolic “keep out of reach of young children” warning labels are as effective as “skull and crossbones” warning labels.