I'm shopping for brass or stainless ball valve to replace shutoff on a plumbing line. I see on ebay that some valves are advertised as "lead-free" while others are not. I would've assumed ALL brass/SS valves are lead-free. If I'm concerned with lead, do I need to screen specifically for lead?
If you go to your local hardware store, no. Products sold in the US have to be lead free, since 1996
In 1996 Congress further amended the Safe Drinking Water Act, requiring plumbing fittings and fixtures (endpoint devices) to be in compliance with voluntary lead leaching standards. The amendments also prohibited the introduction into commerce of any pipe, pipe or plumbing fitting or fixture that is not lead free.
Ebay is a bit of the "wild west", because you often have products sold direct to consumers from foreign countries (i.e. they bypass US regulations because they're sold and shipped from that country to you directly). It's easy to find Chinese or Indian products on there, and neither country has that prohibition against lead. So, yes, you probably need to screen on Ebay. If it's a serious concern for you, just buy from a US company or your local hardware store.
There are plenty of plumbing fittings used for non-potable water that are still being made which contain lead in the brass alloy. The lead free ball valves usually have a NSF icon on them.
Ball valves are used in many applications and industries and only the ones used specifically for drinking water would need to be lead free.
Its hard to tell if it is lead free or not just by the look, you may have to look up its part number online to find out.