It actually does not take 'dirt' in with it. It only takes in things that are small molecules of a chemical that disolve I it. The worst thing it takes in with it is leg paints and linaments. Some of those can be real damaging like Iodine leg paints. If you look at the label, it is sold as a 'solvent'. That is because it was first marketed as a solvent and they found out accidentally that the molecule is so small that it penitrates skin. It is one of the things that came out in Mexico in the 60s in arthritis clinics.
It is 'bacteostatic'. If you put it on a wound, particularly a puncture, it will rarely get infected. If you add an antibiotic like Gentocin with it, it will kill a lot of hard to get to infections and do as much good as using the antibiotic alone IV.
If you use it on yourself too much (Ihave known people that did including myself once), it will affect your eyesight and blur your vision. It goes back to normal but it scared the heck out of me.
I also used it on a knee injury. I had surgery and then the knee kept filling back up with fluid and had to be frained 3 or 4 times (think 5 inch needle). The last time they stuck a needle in it, I swore they would not do that again and used DMSO on it until my vision blurred. The knee got better, but now I have permanent arthritis in it. -- which I was going to get no matter what.
It is really great for sprained fingers and wrists. I have had a sprained (swollen double in size) go down in 1 or 2 days with it. My son (28 years old) used it yesterday on a puncture where he got a steel splinter in his finger and it swelled all up and he could not even pick anything up with it. Now, it will get better without antibiotics, but I will have to keep reminding him to get a tetanus shot just in case.
I've been around it since it first hit the race track in 1961. Amazing stuff in the right place andnot over-done.