Flush or throw?

I have had a cold. Today, as I was blowing my nose, it occurred to me that I don't know which is more environmentally friendly - to flush the tissue (I suppose to be at all green I would have to just put it in the toilet and wait for the next mandatory flush, assuming that whomever is next to arrive doesn't mind having it there) or to put it in the garbage. I'm assuming that my usual method of dealing with trash I don't know how to recycle (that is, lighting it on fire and holding it out my window) is not a good option.

Seems to me that if I flush, there are probably fewer germs being spread, and that's probably a good thing. And it does seem that tissues pretty much disintegrate in water, so even though I know it must theoretically end up somewhere, it kind of feels like it should be pretty easy to deal with. On the other hand, a tissue is not going to take up much room in a landfill, and, without getting into the details of the organic matter it holds, should decompose rather quickly.

If I were an environmental engineer, that's what I would study.

And that makes me think of something else... if I decided to change course now and re-educate myself for another career, what would I choose?

Sociologist - I would study the subculture of the US or Canadian "Bible belt". Not sure exactly how this one would translate into an income of some sort, but it would sure be interesting.
Author - probably erotic vampire fiction, but it's hard to know until I get started how that would go. If it didn't work out I would likely do children's stories.
Art historian - specialising in 15th century Flemish masters and eventually curating at the Groeninge Museum in Bruges. I am ideally suited to this except for my complete inability to remember names, dates, or events.
Recording engineer or producer - the dream that will not die.
Designer - probably furniture, but maybe an architect. I love nice things.