In the early years of the 20th century, there was a craze of medical quackery following the discovery of radioactivity in 1896 and the isolation of radium in 1898. Radioactive quackery quickly spawned numerous products which claimed to have a variety of medical benefits. Many of these products were completely bogus, but some, to the detriment of their buyers, were actually genuine. Radithor, for example, was a patent medicine composed of distilled water containing at least one microcurie of radium salts. Wealthy U.S. industrialist Eben Byers, who ingested large quantities of the stuff, died in 1932 of a variety of cancers and degeneration of his bones. He was buried in a lead-lined coffin.
Well, that was then and this is now, right? Certainly we’ve learned the risks of radiation, how silly people were to think of radiation as a medical panacea or fountain of youth, and people in developed countries are protected by their powerful and benevolent health and safety regulators, right? Right?
Wrong. Do a search for “negative ion bracelet” on Amazon or eBay. You will find a long list of products, many manufactured in China, which claim a litany of health benefits from “negative ions” they are said to produce. Now, many of them are completely bogus, and are made of materials such as titanium, copper, and permanent magnet alloys which produce no ions whatsoever. But like the original radium craze, even worse, some of them do produce ions, or at least, ionising radiation, by containing thorium, usually in the form of thorium dioxide. Thorium and its daughter nuclides, including isotopes of radium, actinium, radon, polonium, lead, bismuth, and thallium, emit alpha, beta, and gamma radiation.
One of the bracelets, when tested, was found to expose the skin immediately beneath it to radiation of 5.6 microSieverts per hour, which is equivalent to a dental X-ray every two hours. Background radiation at Fourmilab is around 0.16 μSv/h, so this is around 35 times higher than background. Worse, some of the bracelets simply have thorium dioxide powder embedded in silicone plastic and, as the plastic ages and erodes, are likely to shed radioactive dust that can be inhaled, which is about the worst thing that can happen with radioactive material, especially alpha emitters.
Here is a video from The Thought Emporium analysing a variety of these “negative ion” products and the radiation doses they deliver and the consequences thereof.
Oh, and there is no evidence that negative ions have any health benefits at all. Air ionisers can be useful in removing particulate matter contamination from air and reducing static build-up which can damage electronics, but these are effects which have nothing to do with the claims for these medical quackery products, radioactive or not.