Jeffrey Lewis“New” Radiation Symbol

Somehow, I missed that a couple of years ago the IAEA and the International Organization for Standardization (ISO) released a new symbol for ionizing radiation.

For a field that spends an inordinate amount of time trying to place the real risks from radiation in some sort of perspective, I am not sure this sends precisely the right message.

Unless, of course, that message is: RUN FOR YOU LIVES WE ARE ALL GOING TO DIE!!!!!!!!!

Then, it’s totally great.

Late Update | 11:42 am 23 May 2011 Sometimes the most valuable posts are the ones where I come off looking like a jerk. In those cases, a reader writes in with a patient explanation that helps enlighten the community as a whole.  It’s a trifle embarrassing to discover that I am Simplicio in the dialogue, but at least it is for a good cause.

As Ayhan Evrensel points out, the sign is supplementary, intended for the casings CAT 1, 2, 3 sources. Had the symbol been in use, for example, in the 1980s, we might not have had the Goiânia incident, which killed 4 people and sickened many others.

I apologize for adding to the confusion, rather than reducing it.  And, again, I reminded what a wondeful resource my readers really are.


  1. FSB (History)

    Actually radiation effects on humans are typically underplayed not overplayed. But liked the old symbol better.

  2. ospalh (History)

    The symbol is to be placed on the device housing the source, as a warning not to dismantle the device or to get any closer. It will not be visible under normal use, only if someone attempts to disassemble the device.

    The point was, i guess, to avoid something like the Goiania accident were some people who apparently didn’t know what they were doing stole a medical radiation source and played around with it.
    In this case a “RUN FOR YOUR LIVES”-message like this might have been helpful.

  3. Andrew Tubbiolo (History)

    I remember years ago, maybe even decades ago, when there was talk about how to placard Yucca Mntn. At the time, the article mentioned a ongoing discussion about how to order a pictogram in such a way that there would be no mistaking the warning to indicate the contents were a agent of death, and not a means of raising the dead from the grave. I’m reading into the problem, but it seems as if they were assuming anyone exploring the site was doing so as a result of having forgotten about the contents of the dump. It’s a fascinating question of how to hand this gift to the future, when the gift keeps giving into a very very far future.

    • Alex W. (History)

      Peter Galison and Robb Moss are currently working on a documentary about nuclear waste, and in the rough clips I have seen, they have a great segment about the sci-fi imaginings regarding the protection of the WIPP site from human beings in the far, far future.

      In the early 1990s, the DOE called in all sorts of people to tackle the question of communicating with the future — anthropologists, linguists, science fiction authors, futurists, and people who worked at SETI and other areas concerning extraterrestrial intelligence. Because communicating with someone 10,000 years from now is really not too different from communicating with an alien: they might not speak our language, they might not understand our science, they might not understand our metaphors, etc. They produced some pretty far-out scenarios and some amazing architectural designs.

      Of course, the more elaborately we say “stay out, death lies within,” the more we sound like the curses written on the entrances of Egyptian tombs — and we know how well those kept out intruders!

    • Allen Thomson (History)

      Deep Time, by Gregory Benford, ISBN 0-380-79346-6, Part One.

    • John Bragg (History)

      “no mistaking the warning to indicate the contents were a agent of death, and not a means of raising the dead from the grave.”

      This one’s pretty good, in that it seems to imply that if you disturb the sacred relic (trefoil), that the angry dead WILL rise and pursue you as you flee.

  4. Reece Pendleton (History)

    I showed this to my seven-year-old who suggested that it was a sign informing pirates and joggers that there was a cooling fan up ahead. They might want to rethink the redesign.

  5. anon (History)

    “Actually radiation effects on humans are typically underplayed not overplayed.”

    By whom – the MSM?

    • FSB (History)

      TEPCO, e.g.

  6. sanman (History)

    Actually, to me it looks like the symbol is saying:

    “Watch out for Giant Mutant Skeleton Zombie Skulls, Dr Freeman! Your next portal exit is that-a-way!”

    Are you sure this isn’t a patch issued by Valve Software?

  7. Alex W. (History)

    My understanding is that this warning was just to be used on the very heart of the really radioactive stuff. The idea was that studies had shown that the traditional trefoil meant absolutely nothing to people who were undereducated or illiterate or very young — they thought it was a windmill or a flower. They didn’t get that there might be a hazard.

    As a symbol, the nuclear trefoil is pretty poor. Its source image (an atom with radiation coming out of it) is abstract to say the least, and not even obvious if you actually know what it is supposed to be. It was invented at Berkeley in 1946 by health physicists (nice page on this here: and as far as I know had no testing as to whether it was a good symbol or not.

    By contrast, the biohazard symbol (created in the 1960s) was chosen from a group of many other candidate symbols, tested against focus groups, and calculated to be both recognizable and striking. I think it is more intuitively “scary” than the radiation symbol — the ends of the lines are sharp and uninviting.

    • Alice (History)

      Excellent point. If you compare the Class 7 labels in this Hazmat guide to others, the gap in comprehension is distinct. The label for Oxygen directly communicates a fire hazard. I have a friend in logistics for a trucking company, they’ve only ever handled Americium. However, despite the supposed universality of the trefoil he couldn’t think of how they might label a truck for a shipment of radioactive materials.

    • Alex W. (History)

      It also doesn’t help that many people confuse the the Civil Defense fallout shelter graphic with the radiation warning one — they mean completely different things. Using the same general symbol for “come in here to be safe!” and “stay away from this!” must have seemed very clever at the time.

      (There is a nice page on the origins of the fallout shelter design here:

  8. Bradley laing (History)

    19 May 2011 Last updated at 02:55 ET

    Work on Trident nuclear renewal gets go ahead The renewal of Trident has major financial and political implications

    The defence secretary has given the go-ahead for initial work to begin on the replacement of Britain’s Trident nuclear weapons system.

    Liam Fox approved the £3bn first design stage for replacement submarines, saying Trident was the “ultimate guarantee of national security”.

    The coalition has delayed the final decision until after the next election amid Lib Dem concerns over its cost.

  9. Ayhan Evrensel (History)

    I happen to be involved in the public launch of the “Supplementary Radiation Warning Symbol”, when I was at the IAEA. It is the result of years-long human factor studies, including several tests on pre-school kids. It is a great example of non-verbal communication of risk and threat, independent from culture, language, age, gender.

    This symbol is meant to be used only on the casings/shields covering CAT 1, 2, 3 sources. In other words, this is the last “healthy” sign for an illiterate person trying to break into the metal shield, or if you don’t understand what is written on the casing because it’s in a different language…

    Somehow people took this SUPPLEMENTARY sign too seriously and started putting it even outside an X-ray examination room, where patients wait for their turn, as I recently saw in an Abu Dhabi hospital. I’m afraid, this Wonk story adds more to this confusion.

    Wonk Readers must read the link to IAEA story in Jeff’s entry, to understand the context:

    There, it is explained that the yellow-black trefoil is NOT replaced and this one is only supplementary to it; that a normal person who is not messing with any source will NOT see this sign, etc.

    In short, this symbol would have probably saved lives in Goiania, Georgia, etc. had the kids or the metal scavengers had a chance to see such a scary warning before crushing the metal casings of the caesium.

  10. Spruce (History)

    If the new symbol is reserved to locations and sources which are indeed immediatly dangerous, then it’s good – and it really should evoke that “RUN FOR YOU LIVES WE ARE ALL GOING TO DIE!!!!!!!!!” feeling.

    The problem with the old radiation symbol is that it’s plastered onto every source down to the last, barely detectable Category 5 source up to the most dangerous Category 1 source exactly the same way. I now and then work with very low activity calibration sources that are pretty much totally harmless unless eaten. When you are around them for any longer period and see the trefoil all the time, you soon start to discount it completely. At least once I almost did something stupid with a very active source that was nearby due to that – only looking at the markings there was no way to tell that that one rather dangerous while the calibration sources were nearly harmless.

    As far as I have understood, that new symbol is not meant to replace the trefoil, but to supplant it so that it’s visible only when there’s immediate danger. There’s need for that kind of “more serious” radiation symbol and that seems a pretty good draft of one.

    • John Schilling (History)

      So, how long until use of the new and improved warning sign is mandatory on e.g. the exterior of any device housing a Category 5 sealed radiation source? A few years, certainly, but probably not decades.

    • Spruce (History)

      If it goes that way, the new sign is an utter failure. But regardless, there is a true need for what they are doing and the sign is good for the purpose it’s meant – and that is not replacing the trefoil.

  11. trevor coker (History) will they put this sign up all over japan now ? or will the Carnegie group just tell every one the mox mix is good for you eat it up and then just raise the safe levels up ? . so what happend to the WHAT WAS THE CAUSE OF THE HIGH Cl-38 RADIOACTIVITY IN THE FUKUSHIMA DAIICHI REACTOR #1 ????????

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