Radioactive Iodine and Activated Carbon Filters

I learned something interesting last night that I thought I should share for anyone who is worried about radioactive isotopes of iodine in their drinking water or in the air.

If I remember correctly, the two most common isotopes of iodine that were released in Japan were iodine-131 and iodine-135. First, let me explain the problem that we as humans have with radioactive iodine. Our thyroid gland needs iodine and our body does a great job of absorbing iodine and funneling it all directly to the thyroid, so iodine gets concentrated there. If the iodine is radioactive, then you have a problem because the body is collecting it all and storing it in one small place. Radioactive isotopes of iodine also have short half-lives so there is a lot of radiation given off that could trigger cancer.

Iodine-131 has a half-life of 8 days and iodine-135 has a half-life of 2.3 hours. What that means is if you have 1 gram of iodine-131 then after 8 days you have half a gram of iodine-131 and half a gram of regular iodine (iodine-129). In another 8 days you have a quarter gram of iodine-131 and three quarters of a gram of regular iodine. Every 8 days half of the remaining radioactive iodine becomes inert iodine. Similarly, a gram of iodine-135 you only have half a gram after 2.3 hours and a quarter gram after 4.6 hours, and so on.

I titled this post Radioactive Iodine and Activated Carbon Filters because what I learned last night was that iodine can be filtered out easily with a good activated carbon filter. Did you know that a teaspoon of activated carbon powder has the equivalent surface area of a football field? That’s a lot of surface area for the carbon to absorb and trap contaminants in air and water.

So, the bottom line is that a good water filtration system with an activated carbon component can effectively eliminate the radioactive iodine in drinking water. Likewise, a good air filtration system with an activated carbon component can help to eliminate any radioactive iodine in the air. I say “help” because if you happen to breathe the air in before it goes through the carbon filter then it isn’t going to help you. But if you are in the same room as it then the device will reduce the amount that you are exposed to.

Nikken’s PiMag water systems: the Aqua Pour, Aqua Pour Deluxe, and the PiMag Deluxe Counter Top and Under Counter filters all include a large carbon filtration component in addition to the other filtration stages. The Air Wellness Power5 Pro air filter also has an activated carbon filter stage that the air passes through while being cleaned.

The PiMag water system are here.

The Air Wellness Power5 Pro is here.

Disclaimer: It was stressed to me also that the Nikken systems have not been specifically tested with radioactive isotopes of iodine but based on the performance of carbon filtration with similar substances, it should work. You can think of this as an added precaution if you are concerned. I would say that if you know for certain that your water supply is contaminated that you find a better source and not rely on any device to clean it if at all possible.

Wayne Woodworth