This is not a small issue! Volatile chemicals can be absorbed into the blood stream directly through the skin. I think this is a very real unreported and under appreciated risk. My son is a biomedical engineer and we have frequently discussed the hazards or transdermal absorption of bad chemicals. As a result I now always wear vinyl gloves when handling any aromatic compounds whether it be fuels, paint thinners, lacquers, or gun cleaning solvents, etc. Additionally, the solvent may also carry lead into your system which is also very bad. As much as I really like the smell of Hoppe's No. 9 it is not good to get it on your skin. And, of course, you should certainly always use it with adequate ventilation!! Just a word to the wise. Your kidneys and liver will thank you!