Joseph Herbert on tue 4 nov 97
Marie Curie won two Nobel Prizes and died of radiation induced leukemia or
pernicious anemia, as it was called in those days, at age 67, having worked
with radioactive materials (she invented the term) for 30 years. Her
discoveries (with her husband) included the elements radium and polonium.
Both of these elements are extremely radioactive - the unit of radiation,
the Curie, is based on the number of radiation events per second
(37,000,000,000) produced by a gram of radium - and she worked with these
elements and others, like uranium, as soluble materials in open evaporating
vessels. The fact that she lives so long in such an environment might be
more reason for comment that the fact that she died. She does look aged and
frail in the photos I have seen of her at the end of her life but age 67 is
not young in 1934.
I am not suggesting that people should be careless about radioactive
material, just that some of the hysteria that surrounds the subject is a
result of misinformation or no information at all. For materials like
uranium, the main danger is from ingestion, not from external exposure. In
fact, the amount of uranium 238 required to produce as many radiation events
as one gram of radium is about 1400 pounds, or about 1 cubic foot. (This may
not be exactly correct - I calculated it myself) The radium would be about
1/5th of a cc. Or about half the size of a gram of quartz and not really
noticeable - unless you have a radiation detector or the lights out, so if
the radium is mixed with Zinc Sulfate, the mixture glows brightly yellow,
alone it glows blue. Marie Curie is quoted as saying that, "one of our
pleasures was to enter our workshop at night; then, all around us, we would
see the luminous silhouettes of the beakers and capsules that contained our
products".
It may not be particularly useful to think of the radiation exposure that
Madame Curie accumulated, both internally and externally over her 30 years of
research (and lunch in the lab?!), but it does give one food for thought. We
worry about industrial exposures that are similar to that gained from living
in a mountain cabin. This is as it should be for no one should have to
accept more risk in their life just for a job. But truck driver s do accept
a different kind of risk as do all driver s who venture onto the roads.
There are some 50,000 people killed each year on the highway, far beyond the
number of excess deaths caused by radiation. Some 300,000 people per year
die of smoking related illness. Both of these death tolls are from risks we
think we understand so we accept them, rather gladly it seems. The prospect
of 17 extra cancers in the vicinity of a single nuclear power plant in
Pennsylvania redirected the American power industry and assured that we will
burn lots of fossil fuel in the coming century.
I don t really have a conclusion for this other than to observe that people
are really funny about risk in their lives. A person who goes skydiving or
bungee jumping without a thought is petrified of an unwashed apple. Part of
our response to a perceived risk is controlled by the response of those
around us. This control has produced the result that the nuclear world of
bombs and power plants has, in the past 50 years killed 200,000 to 300,000
people with bombs and maybe 5,000 to 50,000 people with power plants (none,
not one, in this country) while just in this country cars killed 1,500,000
and cigarettes killed 7,500,000.
Anyway, you should be careful with your ceramic materials, you should not
expose your customers to a risk that they don t know of and understand, and
you should be informed, well informed, about what you use and the ways you
use it.
By the way, almost everyone has a little stash of radioactive material in
their house. Your smoke detector contains some and won t work without it.
Another interesting balance of risk. The radiation poses very little or no
risk but what about the fires? A sufficiently negative opinion about
radioactive sources might deny the use of a smoke detector, assuring your
death from fire. The eternal search for balance.
Joseph Herbert
JJHerb@aol.com
Monona Rossol on fri 7 nov 97
---------- Forwarded message ----------
Date: Thu, 6 Nov 1997 08:05:41 EST
From: George Mackie
To: Multiple recipients of list CLAYART
Subject: Re: Uranium in Glazes (was- Re: A little reminder)
Resent-Subject: Re: Uranium in Glazes (was- Re: A little reminder)
----------------------------Original message----------------------------
It was me who opened the can of worms by mentioning uranium oxide as a
yellow colouring agent in Egyptian paste when a woman in Australia,
Deoborah Zinn, posted an enquiry on this topic. SNIP.... As for Uranium,
clearly the potter who uses it should avoid inhaling it but the beads I made
with it gave off no more radioactivity than the background level in the lab
where they checked it for me. SNIP
-----------------------------------------------------------------
I don't know what lab tested the beads or how sensitive the test equipment
they used was, but there is no way a uranium-colored surface is going to be
at background. Our Nuclear Regulatory Commission banned the use of
uranium-containing enamels on jewelry to preclude skin contact with the fired
enamels. Skin contact with uranium-containing Egyptian paste shouldn't be
that different.
Monona
Arts, Crafts and Theater Safety (ACTS)
181 Thompson St., # 23
New York NY 10012-2586 212/777-0062
http://www.caseweb.com/ACTS/
George Mackie on sat 8 nov 97
At 02:22 PM 11/7/97 EST, you wrote:
>
>
>I don't know what lab tested the beads or how sensitive the test equipment
>they used was, but there is no way a uranium-colored surface is going to be
>at background. Our Nuclear Regulatory Commission banned the use of
>uranium-containing enamels on jewelry to preclude skin contact with the fired
>enamels. Skin contact with uranium-containing Egyptian paste shouldn't be
>that different.
>
>
>Monona
Monona- the tests were done in a lab at the Physics Dept of the University
of Alberta in about 1968. George
Monona Rossol on mon 10 nov 97
> Monona- the tests were done in a lab at the Physics Dept of the
University > of Alberta in about 1968. George <
It would be interesting to know what kind of test equipment they used way
back then. A lot has happened in 30 years. Time to take another look.
The Nuclear Regulatory Commission's publication of the re-evaluation of
glazes and enamels (and other consumer sources of uranium) was in 1980.
The re-evaluation and ban on uranium-containing enamels occurred in 1984.
And there are still re-evaluations of the various kinds and levels of
radiation and their health effects on-going.
Monona
Evan Dresel on mon 10 nov 97
There seems to be a lack of understanding of basic radiation physics here.
Uranium is an alpha emitter. I don't know how the lab measured the
radiation from the beads either -- around here they often use a device
called a PAM (Portable Alpha Monitor I think) which is actually quite
difficult to use unless you are dealing with something screaming hot because
..... Alpha particles have very poor penetration properties. You can stop
them with a piece of paper. You can stop almost all of them with the dead
layer of your epidermis. You can stop them with your clothes. You can stop
them with latex gloves. You don't want an internal dose of alpha particles
particularly in the sensitive tissues of your lungs.
Then if you are dealing with pure uranium you are dealing with three
isotopes (four if you are thinking of the mostly spent fuel from a nuclear
reactor which I think we don't need to worry about here). All three
isotopes have very long half-lives. Very long half-life means very few
atoms decay in any period of time. That means there is not much radiation
to detect. If you want to detect it the easiest way is to dissolve up the
material and put it in a liquid scintillation cocktail. That's a special
liquid which emits light when it absorbs those alpha particles. Then you
measure the light given off with very sensitive photomultipliers. The
trouble with trying to measure the radioactivity of the solid is that nearly
all of the radiation is absorbed before it even reaches the surface. Even
more so when measuring the alpha radiation from a small amount of uranium in
a glaze -- It's going to be really difficult to detect.
Ok for those of you who have read all this, what's my point? My point is
that I am not surprised at all that the beads didn't read above background.
We could get into a really esoteric discussion of what "background" is, but
I don't think it is worth it. At the risk of annoying Monona (it has been
known to happen :-() if you consider a single alpha particle more than would
be present if the material wasn't there then she is right: it will be above
background (impossible to measure because the background radiation is
fluctuating constantly with time). But that's not exactly a reasonable test
and is not generally accepted in the scientific community.
-- Evan Dresel who just got back from Santa Fe where he caught a 101 cups
show at a gallery. Some of the cups were ceramic. A couple you could
probably drink from. Most were worth a look.
At 02:22 PM 11-7-97 EST, you wrote:
>----------------------------Original message----------------------------
>
>---------- Forwarded message ----------
>Date: Thu, 6 Nov 1997 08:05:41 EST
>From: George Mackie
>To: Multiple recipients of list CLAYART
>Subject: Re: Uranium in Glazes (was- Re: A little reminder)
>Resent-Subject: Re: Uranium in Glazes (was- Re: A little reminder)
>
>----------------------------Original message----------------------------
>It was me who opened the can of worms by mentioning uranium oxide as a
>yellow colouring agent in Egyptian paste when a woman in Australia,
>Deoborah Zinn, posted an enquiry on this topic. SNIP.... As for Uranium,
>clearly the potter who uses it should avoid inhaling it but the beads I made
>with it gave off no more radioactivity than the background level in the lab
>where they checked it for me. SNIP
>-----------------------------------------------------------------
>
>I don't know what lab tested the beads or how sensitive the test equipment
>they used was, but there is no way a uranium-colored surface is going to be
>at background. Our Nuclear Regulatory Commission banned the use of
>uranium-containing enamels on jewelry to preclude skin contact with the fired
>enamels. Skin contact with uranium-containing Egyptian paste shouldn't be
>that different.
>
>
>Monona
>
>
>Arts, Crafts and Theater Safety (ACTS)
>181 Thompson St., # 23
>New York NY 10012-2586 212/777-0062
>
>http://www.caseweb.com/ACTS/
>
>
Jeff Lawrence on wed 12 nov 97
The well-informed Evan Dresel was talking about uranium:
>Then if you are dealing with pure uranium you are dealing with three
>isotopes (four if you are thinking of the mostly spent fuel from a nuclear
>reactor which I think we don't need to worry about here).
My supplier says he can get depleted uranium dioxide. is this the spent fuel
above? Does it share the stigma of unclean?
Not that I'm really trying to recharge a depleted topic, but the only
weapons workers I know here in Los Alamos play with conventional explosives
and are no help with nuclear stuff. And I remember an exhibit in the
Technisches Museum in Munich (?) with uranium glazed pots and uranium glass.
Press a button to dim the lights and turn on a uv light. Eye-opening at
least and incredibly beautiful at best.
Evan, any observations?
TIA
Jeff
Jeff Lawrence
jml@sundagger.com
Sun Dagger Design
Rt 3 Box 220
Espanola, NM 87532
ph 505-753-5913
fax 505-753-8074
Gavin Stairs on tue 18 nov 97
Hi all,
Defining the emissions of ionizing radiation from a sample can be tricky.
In the case of a small object like a bead, if you simply put it close to a
counter and count, you may well decide that it emits no significant amount
above background, if the area of the counter is large, or a number of other
conditions. This does not mean that the bead is safe to place next to
skin. It simply means that if you live next to the bead (in the same room,
for example) you won't be absorbing any significant dose of radiation.
This is the same effect as being in a room with an incandescent bulb vs.
touching the bulb with your skin. The first is not unpleasant, but the
second is distinctly unsettling. If you wish to try the experiment, you
will find that there is a distance beyond which you cannot feel the heat
from the bulb, but as you move closer you feel it more and more until at a
certain point you begin to feel pain. Exposure to a radioactive source is
like that, only the damage to tissue becomes significant long before you
can feel it because we have no direct sensors to ionizing radiation.
The most damaging radiation for mucosa (lungs, mouth, digestive tract) are
alphas and disintigration products. Alphas may not even penetrate skin,
and they may not penetrate the glaze coat, especially if there is a clear
coat over the colour.
The most damaging radiation for close contact to skin, especially if the
source is buried in a glaze, is beta (electron) or gamma (photon)
radiation. This has the power to penetrate several millimeters of skin. It
will also penetrate a clear glaze coat over the colour.
Uranium emits alphas, betas, gammas, neutrons and fission products. If you
want to know if a bead is safe to place next to skin, you must read the
total activity of the bead and consider that as a skin contact source.
There are standard methods of doing this. The U of Alta test was probably
a simple matter of placing the bead in front of a survey counter for a few
seconds, and judging if the count rate increased significantly, perhaps
more than half again as much as background. This is not a sufficient test
to determine safety in skin contact. I won't go into the correct methods
for testing such a source, since they are somewhat involved, and are the
province of experts. They require sensitive and well shielded counters
sensitive to the appropriate particles, etc.
I would like to emphasize that unless you know what you are doing and take
sufficient precautions, any uranium salt or product is a potential if not
an actual hazard to health, even though no prompt symptoms may be detected.
People who do handle uranium do so under strict protocols regarding
shielding and protective procedures, and with constant supervision of the
level of inhaled particles and body exposure. Under such conditions, it is
possible to handle the metal and even the salt powders safely. In past,
these substances were not handled properly, and many health and safety
problems have resulted. Those who are unclear about the large scale
problems that can result should look into the situation at Rocky Flats.
Another caution: Radioactivity was not discovered until the turn of the
last century. Up until about WW2, the dangers were not appreciated, and
safety protocols were rarely instituted. It is dangerous to use prewar
practice as examples of proper usage, since our understanding has increase
considerably since then. Indeed, most of today's regulations come from the
experience of the Japanese population exposed during the bombing of
Hiroshima and Nagasaki. The legacy of this is that our data is for high
exposures, while what we are discussing is low exposures. There is a
current debate about whether the extrapolated high exposure data is
suitable for the low exposure. This will not be resolved for some time.
It is prudent to continue to regard low level exposures as somewhat
hazardous. Certainly, dust particle exposures in lung tissue are hazardous.
Gavin
At 05:29 PM 08/11/97 EST, George wrote:
>Monona- the tests were done in a lab at the Physics Dept of the University
>of Alberta in about 1968. George
stairs@echo-on.net
http://isis.physics.utoronto.ca/
416 530 0419 (home) 416 978 2735 (work)
Toronto, Ontario, Canada
Wade Blocker on wed 29 sep 99
Milton,
I suppose I qualify as an elder. The uranium that was sold was
"spent uranium" available at any chemical supply place. In a low fire
leadbased glaze it gave reds and oranges. In oxidation at higher
temperatures it acted as a yellow colorant. In reduction it turned black.
Mia in ABQ where the State Fair is over and the balloon festival is about
to begin.
Hank Murrow on thu 30 sep 99
>----------------------------Original message----------------------------
>
>Milton,
>
> I suppose I qualify as an elder. The uranium that was sold was
>"spent uranium" available at any chemical supply place. In a low fire
>leadbased glaze it gave reds and oranges. In oxidation at higher
>temperatures it acted as a yellow colorant. In reduction it turned black.
>Mia in ABQ where the State Fair is over and the balloon festival is about
>to begin.
Mia & Milton; If you soak the reduction fire during cooling, the 'black'
uranium will return to its yellow-green color. Regards, Hank
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