Originally Posted by Whiskey
Just rinse the valve with an acid wash, vinegar, star-san etc. It will be fine unless you decided to suddenly start eating brass valves.
+1 The amounts of lead that might be in the brass have to actually get into your body. They can't migrate there through magic. I cast my own bullets for reloading for 20 years; a lot of this was in a basically poorly ventilated space. After I quit casting, I was motivated to have a test for lead levels. Guess what? Background levels, no more than might be expected in the general population.
A lot of the stuff floating around about chemicals and radiation is just the purest superstition and speculation, and the Internet just makes this grow worse, and exponentially*. You will get more radiation flying in a jet from NY -> LA than you will from working a lifetime in a nuclear power plant. (In the plane, you're flying above most of the Earth's atmosphere, and thus are exposed to a lot of radiation from space, whereas the reactor is quite well shielded.)
*Note: According to comedian Lewis Black, "Halftime at the Super Bowl is the best because halftime at the Super Bowl has gotten exponentially worse every year. I use the word 'exponentially' because I was taught it in math class and that was the first sentence I could use it in. 'Exponentially worse' means crappier and crappier and crappier."