The top tube is fine being plasic as almost no heat goes to it, however the one that is attached to the bowl should get changed. That very could easily get burned and give off bad fumes.
NotALlama Reviewed by NotALlama on . tight mini-bong! This is my devious mini water-bong. It's only about 6 inches tall but it'll get the job done let me tell you. Rating: 5