Simple devices keep toxic products off-limits to children.
The safest storage solution is to keep cleaning supplies completely out of children's reach. When that's not possible, a magnetic lock mounted on the inside of the cabinet door, like the one pictured here (Safety 1st Cabinet Hinge, about $18; go to safety1st.com for store locations), is the next-best option.
When you close the cabinet door, it locks automatically. To unlock it, you pass a magnetized "key" across the front of the cabinet. To disarm it, you flip the red lever inside. Interior cabinet latches require installation. If you're not handy with a screwdriver, a childproofing service can install locks and perform a safety assessment of your entire house. Contact the International Association for Child Safety (iafcs.com, 888-677-4227) to find a service near you.