I believe we have met the criteria for this many times. Our boys have all been interested in varying degrees with fire. I have written about it before here and here.
Allowing kids to light, experiment and play with fire might be an experience that many parents balk at. I think it is an experience that can allow them to develop competance at an early age. Being around fire lets kids literally 'feel the heat', understanding quickly the boundaries that must not be crossed to ensure their own safety. In my experiene, kids that have not be adequately introduced to fire tend to act the most irresponsible when around it.
I think it is important to speak to children about these things in the positive. I don't believe in telling kids they will burn themselves or set their surroundings on fire. We inform them of the proper way to be around and handle fire and what to do if things do not go as planned. Being able to start and maintain a fire can be a life-saving skill.
Dangerous? Only if you are not prepared to give your kids the information and latitude they need to develop responsibility around fire.