I read recently (on here I believe) That some older whistles have a lead fipple, or at least contain lead somewhere. I was wondering if anyone can tell me more about the particulars? Who made whistles with lead and when did they stop? Is there anything to look for when buying online that might signify a whistle that has lead in it? Other than directly looking at the fipple that is. I saw some people who said to put nail polish on the lead to make it safe to play, or replace it. Any other suggestions? Thanks!
I assume you are referring to this thread.
Quite a few of the older rolled tin whistles used lead in the fipple. These were made long before anyone determined or accepted the fact that ingesting lead can cause brain damage. If you are not buying or playing antique whistles you have nothing to be concerned about. Modern manufactured whistles, at least those coming from the consumer safety conscious parts of the world, will not contain lead in the mouthpiece. All you have to be concerned about (depending on what whistles you play) are the compounds used to formulate modern plastics, metal allergies, exotic wood sensitivity, and so on. 
If you dig deep enough you will find someone that has a concern about most every material used to make whistles.
It’s all about choices and keeping yourself informed.
The suggestion that you coat a lead plug with nail polish is intended to keep the lead from leaching into the mouth while playing. That way you only make contact with tin and the acrylic lacquer of the nail polish.
Feadoggie
That is indeed the post I referred to, and i figured that it wouldn’t be included in modern manufacturing. I am looking at collecting older whistles though.
Yes, collecting is a fun activity. You never know where one will turn up. It’s best if the old whistle has a story to go with it too. Enjoy it.
As for which whistles have lead fipples, I would just assume that if the whistle has a metal plug then it is likely to have a high lead content. Lead and lead alloys were just so easy to work with. So even if the fipple isn’t solid lead it is likely to be a “pot metal” or what they called “monkey metal” which would likely have lead as a major component.
Feadoggie