Liable is a bit strong word here, liability without fault is mainly rejected concept in modern world.
Imagine you are a shop selling cola in can.
If coca cola company put some unhealthy stuff in, you are not liable just for selling it. But if you made the stuff unhealthy because you stored it in direct sunlight long time, you are liable.
I bought "child's toy" and sold you "child's today", you expect seller to check every toy if there is "secret camera" ?