Tritium Keychains.. Watchout.

[Bradlee]

How long does tritiated water reside in the body and how many grams of inhaled tritium would it take to do as much damage as say a common medical xray.

From this article: "Tritiated water is taken up readily by cells and is eliminated over an extended period with a biological half-life in humans of about 10 days (I), producing a chronic radiation exposure."

With regards to your latter question, what I got out of the HPA article sited above is that scientists don't agree on the relative biological effectiveness of beta particles relative to x-rays (though the consensus seems to be that it's higher), so it's hard to calculate an accurate figure.

 

[Nanomiser]

We use a Ludlum 44-6. It detects Primarily Gamma, but Beta too. It uses a Geiger-Mueller tube. I would guess a scintillation crystal sensor (more sensitive) would be needed to detect the level of Beta that small tritium tubes emit.

We also use a Ludlum, Model 3 Survey GM with a 44-9 pan cake head detector which is set up to detect Alpha beta & gamma radiation. I conducted a little test with 6 of Bart's ice-blue 1.55mm X 5mm vials just to see what would happen and got a surprise! :sick2:

With the range set on 1X and the detector head sitting right on top of the shipping bag the GM was picking up between 900 & 1100 counts per minute through all of the packaging. I thought the low energy of tritium beta couldn't even breach the glass vial envelope let alone the packaging to.

Only after I covered the shipping bag with some copper foil did it knock the count down to 100 to 200. Finally I laid a 1/16" thick aluminum plate on top of the foil and the count dropped off to back ground levels.

Bart doubts that any leaking is occurring, but yet the radiation being detected is behaving like beta or very low energy gamma.
Does anyone have any ideas on what is happening here?

Mike

 

[cruisemissile]

I didn't understand a word of what was just said.
I cant keep up with "nuk-u-lar" scientists.

I have wanted a tritium fob for a while , to match the tritium sights on my stainless .45, but haven't gotten around to it.
pending an answer to the safety of these t hings, I shall see if I will still get one.

 

[Bradlee]

We also use a Ludlum, Model 3 Survey GM with a 44-9 pan cake head detector which is set up to detect Alpha beta & gamma radiation. I conducted a little test with 6 of Bart's ice-blue 1.55mm X 5mm vials just to see what would happen and got a surprise! :sick2:

With the range set on 1X and the detector head sitting right on top of the shipping bag the GM was picking up between 900 & 1100 counts per minute through all of the packaging. I thought the low energy of tritium beta couldn't even breach the glass vial envelope let alone the packaging to.

Only after I covered the shipping bag with some copper foil did it knock the count down to 100 to 200. Finally I laid a 1/16" thick aluminum plate on top of the foil and the count dropped off to back ground levels.

Bart doubts that any leaking is occurring, but yet the radiation being detected is behaving like beta or very low energy gamma.
Does anyone have any ideas on what is happening here?

Mike

Using this reference which someone on EDCF just pointed out, I conservatively calculate an activity of 150MBq/mm for a 1.55mm vial. At 5mm, that works out to ~750MBq per vial, or 4.5GBq for the 6 you used. This 4.5 billion decays/sec is 0.27trillion decays/min so (if my calculations are correct) you're only picking up 1100/0.27T = 0.00000041% of the total beta emissions. That said, most of the beta particles would be reacting with the phosphor coating in the vial.

I suppose that was a round-about way of saying that there's a lot of activity in these vials. Even though most beta particles will annihilate when they hit the phosphor, some will make it past. It's said that 1mm of dense material is enough to stop the low energy beta particles produced by tritium but, looking at the above reference, we're talking about glass thicknesses of a fraction of a mm so some are bound to make it out.

Note that even with larger vials, where glass is thicker and they are encased in plastic, etc, the assertion that 1mm of dense material will stop the beta particles is only a statistical probability. Although the average energy for a beta particle is ~5.7keV, some can be up to 18.6keV.

 

[Nanomiser]

Thanks Brad for quantifying my readings.

The real question is given this level of beta radionuclide activity, what duration of exposure would someone have to under go before it becomes a serious health risk. Assuming external exposure, the risk is also influenced by what part of the person is exposed.

I just went through similar exercise in dealing with thorium exposures both external and internal. I need to get some more data on maximum allowable exposures limits and body burden level for tritium.

Mike

 

[Bradlee]

The real question is given this level of beta radionuclide activity, what duration of exposure would someone have to under go before it becomes a serious health risk. Assuming external exposure, the risk is also influenced by what part of the person is exposed.

I just went through similar exercise in dealing with thorium exposures both external and internal. I need to get some more data on maximum allowable exposures limits and body burden level for tritium.
Mike

I'm confused, are you talking about exposure to tritium (i.e. a broken vial), or its beta emissions?

 

[Tachikoma]

So how much do I risk, considering that I edc a 30mm tritium vial near my liver?

 

[Nanomiser]

I'm confused, are you talking about exposure to tritium (i.e. a broken vial), or its beta emissions?

I'm talking about both external and internal beta emissions exposure. Since the tritium is contained in glass I would like to better understand the worst case scenario of tritium inhalation (i.e. broken vial) as well the external exposure (i.e. beta emissions thru the glass).

 

[Bradlee]

I'm talking about both external and internal beta emissions exposure. Since the tritium is contained in glass I would like to better understand the worst case scenario of tritium inhalation (i.e. broken vial) as well the external exposure (i.e. beta emissions thru the glass).

Ah, okay. I'm not so much worried about a broken vial myself, but I'd really like to get a better hold on the effects of these relatively low energy beta particles.

I hope you can find the information you need to analyze both types of exposure in more detail. If I have some time, I may try to do the same, but I'm not sure if I have a sufficient knowledge base :shrug:.

 

[Nanomiser]

I just had a member send me with what looks to be, a very useful industry contact. I will call this guy next week and see what he has to say. Time allowing, I'll try to summarize what information I get and post it here.

Thanks for your correspondence,

Mike

 

[cdosrun]

I worked in a school a while ago and tried their Geiger Muller tube and counter over the holidays. I put 8 or 9 of the 1.5mm [email protected] phails near the tube and, as experienced above, the count was several times above background levels. I also placed a friend's commercial tritium key-ring fob in front of the counter and obtained lowed counts than just one of [email protected] 1.5mm tubes.

The upshot is that [email protected]'s tubes are very good value! I have one of the large titanium/tritium fobs now and am keen to see what is coming off of it.

As for risk, I am not especially concerned, when these items are in your pocket, the emissions usually have at least a few layers of fabric until they contact your skin, and then at least several mms of dead skin cells until anything capable of being damaged by them. I don't think the risk from direct emissions is even worth considering.

As for inhalation dangers, some time ago I ran through the calculations, percentage of hydrogen recombined to water, percentage water absorbed, half-life within the body etc - again, this was purely for interest, I don't consider these to be a tangible risk. The results were quite comforting, for the occasional one that breaks, it isn't worth thinking about. If you were to inhale a few hundred, you might be advised to increase your water intake for a week.

Andrew

 

[Nanomiser]

So how much do I risk, considering that I edc a 30mm tritium vial near my liver?

First you need to know what level of radioactivity you are being exposed to, the type of radiation (beta) and the duration of the exposure. Then understand the biological / physiological effect to the liver and do the math from there. I'm no expert so I couldn't tell you anything specific about what to expect.

My main point here is that people need to better educate them selves before making the decision to voluntarily purchase a radioactive source and subsequently becoming exposed to that radiation all in the name of fun. The paraphernalia Bart sells is neat, but I think there is a general lack of understanding the potential dangers of tritium and beta emissions exposure.

I did some research before purchasing my vials, but from what I read I did not expect to get the measure readings I ended up with.

 

[Nanomiser]

I worked in a school a while ago and tried their Geiger Muller tube and counter over the holidays. I put 8 or 9 of the 1.5mm [email protected] phails near the tube and, as experienced above, the count was several times above background levels. I also placed a friend's commercial tritium key-ring fob in front of the counter and obtained lowed counts than just one of [email protected] 1.5mm tubes.

The upshot is that [email protected]'s tubes are very good value! I have one of the large titanium/tritium fobs now and am keen to see what is coming off of it.

As for risk, I am not especially concerned, when these items are in your pocket, the emissions usually have at least a few layers of fabric until they contact your skin, and then at least several mms of dead skin cells until anything capable of being damaged by them. I don't think the risk from direct emissions is even worth considering.

As for inhalation dangers, some time ago I ran through the calculations, percentage of hydrogen recombined to water, percentage water absorbed, half-life within the body etc - again, this was purely for interest, I don't consider these to be a tangible risk. The results were quite comforting, for the occasional one that breaks, it isn't worth thinking about. If you were to inhale a few hundred, you might be advised to increase your water intake for a week.

Andrew

That is reassuring and I would tend to agree with you. However, when it comes to radiation exposure outside of the doctors / dentist office I need to be more informed.

 

[StarHalo]

Could one of you with a detector and a Bart vial please also run measurements on a banana and compare the numbers? It'd be nice to have something real-world to contrast the data to..

 

[[email protected]]

Quoting the manufacturer:

The graphic below shows the average natural does for the Swiss population in millisievert per year (mSv/a), compared to the incorporation of the total activity of one watch equipped whit trigalights (25 mCi / 1 GBq).

I'm expecting a PDF file about tritium safety from them this week, when I have it I will post it here.

 

[StarHalo]

Wow, a whole pie chart that even specifically includes bananas, nicely done [email protected] :thumbsup:

This is pretty much what I was thinking, that you get more radiation from common objects and naturally occuring sources than you ever could from a vial.

 

[Bradlee]

Could one of you with a detector and a Bart vial please also run measurements on a banana and compare the numbers? It'd be nice to have something real-world to contrast the data to..

I'd also be interested to see this although, by my calculations, the long half life of potassium-40 (1.28 billion years) means the average banana only has an activity of ~1.6mBq, several orders of magnitude less than we're talking about.

Quoting the manufacturer:
I'm expecting a PDF file about tritium safety from them this week, when I have it I will post it here.

Awesome, thanks :twothumbs.

Looking at the chart my EDC tritium (assuming identical exposure as from the watch) adds up to the Swiss annual exposure from food, terrestrial and medicine sources combined...

 

[Nanomiser]

Thank you Brad.

 

[Nanomiser]

Quoting the manufacturer:



I'm expecting a PDF file about tritium safety from them this week, when I have it I will post it here.

Thank you Bart for the follow up; I'll be looking for your post.

Mike

 

[mpteach]

What would the counts be for a merkeva diy glowring?

What are the counts from a crt tv.?