Couldn't tell you because there is no way to know what kind of metal or material the cap is made of or whether there is anything else coated on it that could be harmful. Maybe it is safe but ghetto smoking devices have always been a bitch to me, makes it harsher than it has to be and usually wastes smoke. A metal or glass pipe and other smoking devices are usually available at head shops, flee markets, gas stations...CVS sells corn cob pipes for like $5 that can fit a lot of weed, hit smooth and taste decent.

Here are some other suggestions: http://www.overgrow.com/growfaq/1454
Nullific Reviewed by Nullific on . safe alternative to aluminum? ive been aware of the danger of using aluminum foil for a while but never really did anything about it but recently ive been looking for alternative ways to smoke home-made because i am so broke, so i got a IBc rootbeer cap and took out the rubber and scraped all of the cover metal off and poked holes... does this have any harmful effects? Rating: 5