Suntans are caused by exposure to solar radiation. This exposure over the course of many years can lead to skin diseases, including skin cancer. So yes it is dangerous over the long term.

Because they can cause Cancer. I'm not 100 % sure how they do this but I suspect it has something to do with radiation. If I were you I wouldn't do it at all, but it's YOUR body and therefore YOUR choice.

melanin is what controls your skins ability to tan or to sunburn

The more melanin, the easier and darker you can tan. Albinos who have an absence of melanin do not tan, but they can sunburn very easily.

The pigment melanin. It's also the pigment that makes suntans. The difference is that some people have that pigment all of the time, and others have it only when needed to protect the skin from repeated sun exposure.

According to SOWPODS (the combination of Scrabble dictionaries used around the world) there are 4 words with the pattern S-N-AN-. That is, seven letter words with 1st letter S and 3rd letter N and 5th letter A and 6th letter N. In alphabetical order, they are:

sanpans

sunland

suntans

syntans