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Anything that claims to be "negative ion" producing is immediately suspect.
At best, they're absolutely fake, hope that's what you get.
At worst, they do actually produce energy. But the only way to do that with a 2020 understanding of physics is by it having an energy source. They don't take batteries. Instead they tend to be thorium powder, that's extremely fine radioactive dust, either bonded into the plastic or just contained in a pouch. It's probably not that dangerous to hold, but prolonged contact with a small patch of skin (bracelet or necklace) worries me.
The real danger comes from spreading it around the environment and breathing it. If it's bonded into plastic then abrasion and uv are going to break it down and spread microscopic amounts around you. Not great, but considering the size of the world, probably not awful. Except its likely to build up where you hang around, so in the house and in your bed. Not clever...
The lanyards are even more insane though. Its a decent amount of radioactive dust, in a thin plastic bag. A plastic fucking bag. I despair, honestly. That's not going to last a decade, nevermind the next x billion years its gonna take to reach half life. Are either style of product going to be disposed of safely when they reach the end of their (dubious and questionable) useful lifetime? Are they fuck.
Anyway, most of them are a complete con and don't contain anything - and of that we should all be extremely grateful.
You'd have thought the world learnt its lesson though the Allies' use of Radium in all sorts of insane and deadly ways for the first half of the last century. The Radium Girls painting it onto watchfaces is the cautionary example that's most well known, but there were all sorts of quacks putting it into into medicines and creams with (in hindsight), obvious results.
It shouldn't be surprising, I guess, we do have form. Asbestos (everyfkinwhere, even bonded into plastics, metals and glue) and lead (paint, petrol, pipes, makeup and more) have been impressively bad, but we've learnt from it and most places now have rules in place to stop it. We've understood the dangers of radiation for over half a century, we've already learn this lesson. How can any form of this batshit half-assed quackery be tolerated or believed?
The Thought Emporium and others have some good videos on YouTube. "thorium negative ion" gets you there.
(entirely NOT sarcasm, somewhat angry though. I discovered this about a year ago when a mate brought in a laptop that kept crashing and corrupting the disk. Entirely covered in negative ion stickers for protection. Did not expect to need a Geiger counter in my computer toolkit :/)
edited for spelling and vitriol.
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