Here is a great website that discusses both the pros and cons of lowering the drinking age to 18. I strongly encourage you to read it.
http://drinkingage.procon.org/#background
Essentially, I believe that it is wrong to allow someone to smoke, vote, get married, own guns, become a stripper/porn star, sign contracts, go to prison, and most importantly, offer their life for their country, yet not be permitted to consume alcohol.
It is very dangerous to drink without supervision, as many underage people do. By lowering the drinking age, individual safety will increase while drinking. Raising the drinking age hasn't eliminated alcohol related accidents. It has just moved the most alcohol related deaths up a few years.