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One of my readers in the far east has reported to me that members of the general public have been applying betadine to their skin in an attempt to protect themselves from radiation from the stricken nuclear plant in Japan.

As a chemist I hold the view that this application of antiseptic is unlikely to have a useful effect, the betadine contains iodine but as each week goes by the amount of radioactive iodine-131 which could leak out of the reactor site will decline by 50%. So as time goes by the iodine threat will become less and less.

The other major threat from the reactor accident is the cesium; I can tell you that no form of iodine will protect you from the effects of the cesium radioisotopes.

The interesting thing about betadine is that it is a form of iodine which is designed to be less available to human tissues than other forms of iodine, so compared with other iodine preparations I hold the view that it is a bad choice if you want to block the action of radioactive iodine on the thyroid.

I hold the view that the best substance for blocking the absorption of radioactive iodine in the thyroid is potassium iodide when taken orally, I have seen on sale a “vegan” grade of elemental iodine in solution which is intended to act as a protective agent against radioactive iodine. While biology is not my strongest point I will say that sea-weed and mineral deposits are definitely not from the animal kingdom. So any vegans who have made a moral choice to refuse to eat (or use) animal products should be able to use normal potassium iodide or iodine extracted from either sea-weed or a mineral deposit with a clean conscience.

Unless there is some hidden animal product used by industry for the extraction of iodine / potassium iodide then to my mind “vegan iodine” is like “vegan potatoes”. If any vegans are reading this blog then please do let me know if you have any evidence to suggest that an animal product is being used in the production of potassium iodide, iodine or “iodine pills”.

The original isolation of elemental iodine was from sea weed, this was done years ago in the days of Sir Humphrey Davy (The man who invented the miners’ safety lamp), I imagine right now that the vast majority of iodine and potassium iodide is extracted from a mineral deposit. I will have to check my trusty copy of “Cotton and Wilkinson” to check where the majority of the iodine which the world needs comes from.

I thought long and hard about what is betadine, betadine is a complex between protonated poly vinylpyrrolidinone (PVP) and the polyiodine anions which are formed by the reaction of elemental iodine with iodide. It is interesting that elemental iodine has a great ability to react with halides to form polyhalogen anions such as the I3 anion. Some of these polyhalogen anions can be stabilised by polymers such as the PVP in betadine and starch to form interesting complexes. I looked in the Cambridge crystallographic database and I found a series of polysaccharides which associate with poly iodides, these may well be good models for the famous deep blue reaction product of iodine with starch.


2 Responses

  1. The two major producers of iodine in the world are Chile and Japan. There are significant sources in several countries including the USA. The Chilean source is from iodates in tailings of surface mining for nitrates. The Japanese source is from brines associated with natural gas wells. The iodine is found as iodide.

    • Thanks Jim,

      Sounds like neither source of iodine has been part of an animal in the recent past (geological timescale) so it suggests to me that all iodine solutions are suitable for vegans.

      I do question the logic of butting a vegan label on a chemical which has nothing to do with animals, but a few chemicals and lab items are made using animal products such as gelatine. For example I have made reference electrodes using gelatine to make the salt bridge

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