Monona Rossol on tue 18 mar 97
Jim,
Good questions!!
> I just read your post about barium toxicity and have a question for
> you. It does seem to me that might be possible for barium or any other
> element in a glass matrix could show up in spectrophotometric tests
> and still not be soluble. Some reading I've done on the solubility
> of glass matrices in water surprised me (Scientific American - I
> forget the month -several years ago). It seems like it would be possible
> for barium compounds to be liberated by the dissolution of their matrix
> only to be suspended in the leachate tested by the spectrophotometer. The
> barium compound could still be stable in water but decompose in the
> heat of the test environment. If I recall, spectrophotometers use a
> nitrous oxide enriched flame to 'burn' the sample being tested. Am I
> correct about this? <
Nope. Any undissolved or suspended material in the leachate will screw up
the test. The leachate must all be dissolved and crystal clear.
The clear leachate is placed in a small test tube, inserted in the machine, a
special light goes through the liquid and the machine generates a curve
plotting transmittance, reflectance or relative emittance at discrete
wavelengths. The identity of ions can be determined by the pattern of peaks
and the quantity of the ion in the liquid can be determined by peak height.
No heat is involved.
> Do the tests performed on the lead compounds indicate the lead
> availability? Is it possible the the total amount of elemental lead
> in ones blood stream could be high but still not toxic because the
> lead is not 'free'? <
Naaaah! If its there, its a hazard. Remember, your body converts things
like lead from one compound to another very easily with the use of enzymes
and other mechanisms. Chemical conversions that would require heat and
strong chemicals in the laboratory can be done by the body with ease.
> It sure doesn't seem like a leachate test would be a reliable way to
> predict an element's availability in an organism. <
You are confusing two things.
1) Blood lead tests tell you how much lead is in the blood. We then have
tons of data to predict what these levels mean in terms of both immediate
and long term health effects.
2) The leach test is just to see how much lead solubilizes from the surface
of pottery. THere is already plenty of data to predict the lead's fate once
it is ingested from food or drink in the pottery. That is the data that is
used to establish the FDA limits for the leach tests.
> Is there any animal testing that I can read about that discusses the long
> term impact to the test animal? Not just the blood levels of barium or
> lead? <
Again, this is all well-known. Since lead is listed as a carcinogen
by both EPA and IARC (The International Agency for Research on Cancer) there
are two-year tests available (two years=old mice). There are also two
and three *generation* studies of mice and rats to test lead's reproductive
hazards. I suggest you do a search on MedLine for lead/chronic/animal and
you will fill the memory of your computer. I have two floppies full of just
citations and abstracts of such papers!
The only good lead is no lead.
Monona Rossol, industrial hygienist
Arts, Crafts and Theater Safety
181 THompson St., # 23
New York, NY 10012-2586 212/777-0062
http://www.caseweb.com/acts/
Monona Rossol on tue 18 mar 97
Beautiful Ron!!! You said it so much more simply and clearer than I did!
And if we can only make it understood that there are no "safe" frits
regardless of the acid tests. Their large surface area and the ability of
the human gut to dissolve materials make the most insoluble of frits suspect
in the absence of actual animal tests by ingestion.
And let me tell you another outrageous thing about the frit acid test: Step
one in the standard method is to wash out the fines! In other words, in
order to get "reproducible results," the most soluble particles in the frits
are removed before testing. Clever, huh?
Monona
Monona Rossol, industrial hygienist
Arts, Crafts and Theater Safety
181 Thompson St., # 23
New York, NY 10012-2586 212/777-0062
http://www.caseweb.com/acts/
Monona Rossol on wed 19 mar 97
Ric Swensen wrote:
> Barium release from glazes should never occur in amounts that would harm
> anyone...<
Shouldn't but does.
I have lab results on one glaze that released over 3000 ppm on a standard
leach test and a letter from a toxicologist stating that a cup that leaches
800 ppm used for orange juice would be capable of killing a child.
In addition, there are chronic problems associated with barium ingestion.
For this reason, the EPA set a barium maximum contaminant level for your
drinking water at 2 ppm.
> .Lead is a different story...there are many elements that are more
> dangerous than Barium.. Cadmium, Celenium, Vanadium, Strontium <
I agree that there are things that are more toxic than barium that we ought
to worry about even more. And while cadmium, selenium, and vanadium are a
three of them, strontium is not very toxic at all.
> Barium, as I see it, is a red Herring...I think you will have trouble
> finding a case of Barium poisoning in the USA ...or any where else...(look
> in LANCET a LONG time ago for an example of a Pakistani chef in WW II, who
> didn't speak enough English..used Barium INSTEAD of FLOUR in biscuits and
> made his whole battalion ill for a few days.....one elderly officer died
> too. This was a massive over dose of barium...ingested into the environment
> of the human stomach...water...acid...all that cocktail of liquid to break
> down materials)....The truth is that Barium is NOT VERY SOLUBLE...therefore
> it is to be respected....but not feared...<
There was a case of a girl who poisoned her father a few years ago with
barium nitrate that she got from her high school chemistry class. If she
hadn't told a girl friend, she'd have gotten away with it because acute
barium poisoning really looks like a heart attack.
And there are other cases of barium carbonate poisoning since it was used as
a rat poison for so many years.
But acute poisoning is not the problem here. It is the chronic addition of
barium to the diet that people have a right to complain about and potters
must address.
> Further, It is very unlikely that barium glazes that have been "properly
> fired" into a glassy matrix.... will leach enough Barium to make anyone
> sick...but why take the chance? fire your pottery properly...just in
> case.... <
I rely on the good potters of Clayart to take issue with this statement.
Monona Rossol, industrial hygienist
Arts, Crafts and Theater Safety
181 Thompson St., # 23
New York, NY 10012-2586 212/777-0062
http://www.caseweb.com/acts/
Ric Swenson on thu 20 mar 97
I Don't want to argue about the dangers of chemicals......we all should
educate ourselves about the dangers of the materials we work with
daily....I need for you to explain to me how Barium can be soluble enough
to harm anyone...in a fired glaze. I am also interested to know why
Barium Carbonate...if properly handled...would cause a potter problems.
Please recite chapter and verse. The research I did at Dartmouth Medical
School Library was done years ago....so what's changed.?
Read on...
>----------------------------Original message----------------------------
>
>
>Ric Swensen wrote:
>
>> Barium release from glazes should never occur in amounts that would harm
>> anyone...<
>
>Shouldn't but does.
>
PLEASE QUOTE SOURCE FOR BARIUM POISONING...If it is some exotic form of
Barium that potters would never have access to,...please don't bother....if
you are using Barium nitrate as an example...tell me which glaze recipe
calls for that??
>I have lab results on one glaze that released over 3000 ppm on a standard
>leach test and a letter from a toxicologist stating that a cup that leaches
>800 ppm used for orange juice would be capable of killing a child.
Gee, was the sample fired? ( ...he said tongue in cheek)
Documentation on that would be interesting. Leached in what? Something
humans are ever in contact with outside the lab? Forgive my skepicism.
>
>In addition, there are chronic problems associated with barium ingestion.
>For this reason, the EPA set a barium maximum contaminant level for your
>drinking water at 2 ppm.
Because lots of folks were getting sick? or because a lab said it was
POSSIBLE?
Again, please quote your source....Barium carbonate ..the most used form
by potters is VERY insoluble....unless your stomach is filled with
hydroflouric acid. ?
>
>> .Lead is a different story...there are many elements that are more
>> dangerous than Barium.. Cadmium, Selenium, Vanadium, Strontium <
>
>I agree that there are things that are more toxic than barium that we ought
>to worry about even more. And while cadmium, selenium, and vanadium are a
>three of them, strontium is not very toxic at all.
You are right....but which form of Stontium are you calling "not very
Toxic" It boils down to semantics.....what form of Barium are we
discussing?
>
>
>> Barium, as I see it, is a red Herring...I think you will have trouble
>> finding a case of Barium poisoning in the USA ...or any where else...(look
>> in LANCET a LONG time ago for an example of a Pakistani chef in WW II, who
>> didn't speak enough English..used Barium INSTEAD of FLOUR in biscuits and
>> made his whole battalion ill for a few days.....one elderly officer died
>> too. This was a massive over dose of barium...ingested into the environment
>> of the human stomach...water...acid...all that cocktail of liquid to break
>> down materials)....The truth is that Barium is NOT VERY SOLUBLE...therefore
>> it is to be respected....but not feared...<
>
>There was a case of a girl who poisoned her father a few years ago with
>barium nitrate that she got from her high school chemistry class. If she
>hadn't told a girl friend, she'd have gotten away with it because acute
>barium poisoning really looks like a heart attack.
I hope she did not become a potter.
Interesting...anyone using Barium Nitrate in their glazes?
Does it work...is it less expensive....or is it not available because it is
a POISON?
>
>And there are other cases of barium carbonate poisoning since it was used as
>a rat poison for so many years.
>
There are not many examples...and I'll bet they didn't have to do with
pottery?
Tell me which JAMA or other articles you are referrring to.
We are talking about pottery....Barium has not been used as rat poison for
along time....since we came up with other, even worse and toxic stuff to
kill the little rodents....
Read the LANCET article...the reason the Barium was available to the Indian
cook is because rat poison ( a form of Barium mixed with grain, I
believe.?) was there to keep the rats out of the flour and other
foodstuffs. Its NOT good for you....but if we can find so few cases of
"poisoning" why alarm everyone about Barium in general. Spend your time
on lead and cadmium and Selenium..etc...
>
>But acute poisoning is not the problem here. It is the chronic addition of
>barium to the diet that people have a right to complain about and potters
>must address.
>
Documents?
>
>> Further, It is very unlikely that barium glazes that have been "properly
>> fired" into a glassy matrix.... will leach enough Barium to make anyone
>> sick...but why take the chance? fire your pottery properly...just in
>> case.... <
>
>I rely on the good potters of Clayart to take issue with this statement.
>
So, should we fire to the proper temperatures....or not? A barium glaze,
improperly formulated or underfire could leach barium....So fire and
formulate properly and educate people to repect the chemicals we all live
with...not fear them.
As we all know....or should by now.... Underfired lead glaze is VERY
dangerous...properly fired lead bearing glazes...that do NOT leach lead are
usable....enen though it would not be my choice. Proper firing and glaze
formulation are the keys to safe pottery... I still would'nt have lead
around my studio because of my exposure to it in raw form....but there are
people who use it...and with safeguards....are probably not at a terrible
risk....Housekeeping...a clean studio...knowledge of dust dangers are
things we should all work toward. It seems to me that there are a lot of
potters out there that are woefully ignorant about basic chemistry. Hey
maybe I'm one of them....Common sense goes a long way.
I knew this original post would cause a flame...and it's long
overdue....lets hear from more folks...maybe we can educate a few in the
process?
I would be interested to see the documentation of some of your
statements...I learn everyday, hopefully.
Thanks,
Ric Swenson, Bennington, VT
>
>Monona Rossol, industrial hygienist
>Arts, Crafts and Theater Safety
>181 Thompson St., # 23
>New York, NY 10012-2586 212/777-0062
>
>http://www.caseweb.com/acts/
Bill Walker on thu 20 mar 97
I have been watching this discussion, and have been rather shocked
by some of the things that have been stated. As a number of people
have pointed out, it is the barium ion Ba++ that is poisonous and
all compounds are soluable to some extent. The more soluble the
compound, the more Ba++ and the more potential for barium poisoning.
But the reason I decided to post, was to tell my barium story.
A friend developed this beautiful purple glaze that contained barium
and wanted to know if it was safe to use on dinnerware, so I had it
tested. The result was that after sitting overnight filled with 4%
acetic acid, the purple glaze turned PINK. I think that the chemist
reported that the Ba++ level in the acid was off the scale. So if
you visit my friend's studio there is this beautiful cup on display
with a purple rim and a pink inside. The chemist's report is displayed
with the cup.
Someone asked if the amount of barium stays the same with repeated
use, and the answer is no. The accessible barium all gets leached
out after a while, which brings me to the sad story of the couple
on the west coast (I think) who had these beautiful coffee cups.
The cups had a lead glaze, and the lead leached out into their coffee.
But the coffee stained the cups and when they scrubbed to get rid of
stains they scrubbed off the lead-depleted glaze and exposed more
leachable lead. At least one of them suffered from rather serious
lead poisoning.
Bill Walker
Alfred NY USA
Hodaka Hasebe on fri 21 mar 97
I have no opposition to chemists or experts on this field since I do not
know much. ( I replaced Barium with Strontium in some of glaze.) Reading
this thread of barium discussion makes me cerious, though.
I think that the following very serious test results are memtioned without
contexts. Does this apply to all glazes using Barium with any firing range?
Are you suggesting zero tolerance on Barium for food related pottery. If
not, closer to the subject we deal with, like contents of glaze, better I
can understand . And I do want to understand this matter better. Could
you give me more specifics on at least these two examples, such as kinds of
glaze (possibly a recipy) and which cone fired to, or hoplefully in general
guideline--does a type of 1) base glaze make- alkaline, magnesia..etc. 2) %
contents of barium used, 3)type of clay, 4) firing range- cone 6 or 10 make
any differnce?
Thank you.
Hodaka Hasebe Hasebeh@vivanet.com
>Ric Swensen wrote:
>I have lab results on one glaze that released over 3000 ppm on a standard
>leach test and a letter from a toxicologist stating that a cup that leaches
>800 ppm used for orange juice would be capable of killing a child.
> Bill Walker wrote:
>A friend developed this beautiful purple glaze that contained barium
>and wanted to know if it was safe to use on dinnerware, so I had it
>tested. The result was that after sitting overnight filled with 4%
>acetic acid, the purple glaze turned PINK. I think that the chemist
>reported that the Ba++ level in the acid was off the scale. So if
>you visit my friend's studio there is this beautiful cup on display
>with a purple rim and a pink inside. The chemist's report is displayed
>with the cup.
Ric Swenson on sat 22 mar 97
----reply---------
H.
Keep following the thread it gets more interesting all the time...Note that
I have been quoted in error below...it was Monona That said the bit about
the test pieces...I asked to see the documentation....I am as curious as
you...lets get the REAL scoop here.
What indeed is the context of the Barium threat?
Ric Swenson
>----------------------------Original message----------------------------
>I have no opposition to chemists or experts on this field since I do not
>know much. ( I replaced Barium with Strontium in some of glaze.) Reading
>this thread of barium discussion makes me cerious, though.
>
>I think that the following very serious test results are memtioned without
>contexts. Does this apply to all glazes using Barium with any firing range?
>Are you suggesting zero tolerance on Barium for food related pottery. If
>not, closer to the subject we deal with, like contents of glaze, better I
>can understand . And I do want to understand this matter better. Could
>you give me more specifics on at least these two examples, such as kinds of
>glaze (possibly a recipy) and which cone fired to, or hoplefully in general
>guideline--does a type of 1) base glaze make- alkaline, magnesia..etc. 2) %
>contents of barium used, 3)type of clay, 4) firing range- cone 6 or 10 make
>any differnce?
>
>Thank you.
>
>Hodaka Hasebe Hasebeh@vivanet.com
>
>>Ric Swensen wrote: ..no he didn't......Monona did...
>>I have lab results on one glaze that released over 3000 ppm on a standard
>>leach test and a letter from a toxicologist stating that a cup that leaches
>>800 ppm used for orange juice would be capable of killing a child.
>
>> Bill Walker wrote:
>>A friend developed this beautiful purple glaze that contained barium
>>and wanted to know if it was safe to use on dinnerware, so I had it
>>tested. The result was that after sitting overnight filled with 4%
>>acetic acid, the purple glaze turned PINK. I think that the chemist
>>reported that the Ba++ level in the acid was off the scale. So if
>>you visit my friend's studio there is this beautiful cup on display
>>with a purple rim and a pink inside. The chemist's report is displayed
>>with the cup.
Monona Rossol on mon 24 mar 97
Lauren BAll wrote:
----------------------------Original message----------------------------
I've been following this thread for a while and just wonder about some
obvious alternatives. Why not double glaze. Use any glaze you want,
fire. Then put on a nice thick coat of a clear non-toxic glaze over the
top and refire. If the last glaze matures at a lower temperature, I
would think it should protect us from the hazards. Please comment.
-------------------------
Within limits this will work. There is some intermingling of elements during
firing and some toxic substances--especially those that are wanting to fume
at kiln temperatures---can migrate to the surface of the over glaze. But in
the main, this is a good idea.
Monona Rossol, industrial hgyienist
Arts, Crafts and Theater Safety
181 Thompson St., # 23
New York, NY 10012-2586
http://www.caseweb.com/acts/
Monona Rossol on tue 25 mar 97
Hodaka Hasebe wrote,
----------------------------Original message----------------------------
Thank you Monona.
Now I know that some glaze in any firing range may have a problem.
As you stated that "it doesn't look like there will be any way soon to
relate the percent in
the glaze to the amount that leaches on a test" for contents of barium in
glaze, I want to make sure I understand collectly. Let me ask the
following questions, and I assume that answers for following 6 variables
are all YES. Am I right or wrong ?
Have you seen (tested) any corn 8-10 glaze with 2% barium carbonate (out of
total 100%) under any variation (e.g. gloss, matt, alkaline....) which
exceeded the 2 ppm EPA drinking water standard ? How about 10% and 25%?
On the other hand, have you seen (tested) any corn 8-10 glaze with 2%, 10%
or 25% barium carbonate under any variation (e.g. gloss, matt,
alkaline....) which did not exceeded the the 2 ppm EPA drinking water
standard?
Thanks.
hasebeh@vivanet.com
----------------------------------------------
There's just not enough data to answer the question. I have never seen a 2 %
barium carb glaze tested at all. WHat I have seen among the few tests was:
1) There was no linear correlation between percent barium and leaching. Some
glazes with more barium leached less the glazes with smaller amounts of
barium. Some did the reverse. When you see this kind of random
irregularity, you can't draw any conclusions. A lot more data is needed in
order to find what variables other than the amount of barium are operating.
2) There was considerable variation in the same glaze with small differences
in firing temperature. There are not even enough data for me to say for sure
that firing hotter is better than cooler! Although it looks like this might
be the case.
This is exactly why I want people to test their glazes and for schools to
take on this as a research project. It is entirely possible that when we
have hundreds of test results on different glazes at different firing
temperatures, we will then be able to draw some general conclusions.
I haven't seen Janet Deboos' paper yet--have you? What percentage of barium
were her glazes? I think someone said, but I forgot.
TO ALL: a bunch of my messages to Clayart generated a return saying that
the box was full and they weren't delivered. Not only that, these messages
did not include my text so I don't even know which ones didn't make it. I'm
not going to be able to resend.
I thoroughly hope certain Clayart people will not see the unanswered mail as
another sinister plot. Sheesh, lighten up.
Monona Rossol, industrial hygienist
Arts, Crafts and Theater Safety
181 Thompson St., # 23
New York, NY 10012-2586 212/777-0062
http://www.caseweb.com/acts/
Evan Dresel on tue 25 mar 97
At 09:31 AM 3-18-97 EST, you wrote:
>----------------------------Original message----------------------------
>
>> I just read your post about barium toxicity and have a question for
>> you. It does seem to me that might be possible for barium or any other
>> element in a glass matrix could show up in spectrophotometric tests
>> and still not be soluble. Some reading I've done on the solubility
>> of glass matrices in water surprised me (Scientific American - I
>> forget the month -several years ago). It seems like it would be possible
>> for barium compounds to be liberated by the dissolution of their matrix
>> only to be suspended in the leachate tested by the spectrophotometer. The
>> barium compound could still be stable in water but decompose in the
>> heat of the test environment. If I recall, spectrophotometers use a
>> nitrous oxide enriched flame to 'burn' the sample being tested. Am I
>> correct about this? <
>
>Nope. Any undissolved or suspended material in the leachate will screw up
>the test. The leachate must all be dissolved and crystal clear.
>
>The clear leachate is placed in a small test tube, inserted in the machine, a
>special light goes through the liquid and the machine generates a curve
>plotting transmittance, reflectance or relative emittance at discrete
>wavelengths. The identity of ions can be determined by the pattern of peaks
>and the quantity of the ion in the liquid can be determined by peak height.
>
>No heat is involved.
>
>Monona Rossol, industrial hygienist
Facinating. For groundwater and soils analysis the solution is aspirated
into either a flame (sometimes a nitrous oxide-acetylene flame for the extra
heat) in order to form free atoms. Then a light of a characteristic
wavelength is passed through the flame and the element in question is
measured by atomic absorbtion of the light. More commonly these days, the
solution is aspirated into an argon plasma (Can you say very, very hot?)
forming free atoms which are measured by atomic emission spectrophotometry.
So heat is most certainly involved. Perhaps you are mistaken or perhaps
there is a method I should be looking at for trace metal analysis.
-- Evan Dresel
Gavin Stairs on wed 26 mar 97
Monona wrote:
>>The clear leachate is placed in a small test tube, inserted in the machine, a
>>special light goes through the liquid and the machine generates a curve
>>plotting transmittance, reflectance or relative emittance at discrete
>>wavelengths. The identity of ions can be determined by the pattern of peaks
>>and the quantity of the ion in the liquid can be determined by peak height.
>>
>>No heat is involved.
Evan wrote:
>Facinating. For groundwater and soils analysis the solution is aspirated
>into either a flame (sometimes a nitrous oxide-acetylene flame for the extra
>heat) in order to form free atoms. Then a light of a characteristic
>wavelength is passed through the flame and the element in question is
>measured by atomic absorbtion of the light. More commonly these days, the
>solution is aspirated into an argon plasma (Can you say very, very hot?)
>forming free atoms which are measured by atomic emission spectrophotometry.
>So heat is most certainly involved. Perhaps you are mistaken or perhaps
>there is a method I should be looking at for trace metal analysis.
Both right. There are many methods of spectroscopy or spectrometery. The
words simply mean that a range of a particular variable is expanded and
measured more or less continuously by some method, by analogy to passing
light through a prism. The first spectroscopy was optical, measuring the
intensity of light at a range of optical wavelengths. There are at least
two methods of optical spectroscopy, which are described above by Monona and
Evan.
The hot flame spectroscopy described by Evan measures mostly atomic spectra:
everything is broken down to atoms, or more properly atomic ions, and their
emission lines are observed. In the hay day of optical spectroscopy, most
of the hitherto unknown natural elements were discovered in this way.
Notably helium was discovered by noting its absorption lines in the solar
spectrum. The presence and intensity of lines permits the amount of the
element present in the sample to be quantitatively estimated. This is still
one of the fundamental methods of astronomy, for example.
The aqueous spectrophotometry described by Monona is used to determine ionic
concentrations in aqueous (water) solution. These ions may be atomic, or
radicals, like CO3--. In this case a light is shone through the liquid, and
the absorption spectrum is recorded.
There are many other kinds of spectroscopy. Mass spectroscopy and gas
chromatography are used to analyze gasses by molecular mass. Ion source
mass spectroscopy may be used on refractory samples. X-ray spectroscopy
uses a different range of the electromagnetic spectrum. Then there's
positron emission spectroscopy, neutron activation, nuclear magnetic
resonance, secondary electron emission, and the list goes on.
The one thing all methods have in common is that they require expensive
apparatus to perform, and lots of experience and calibration to interpret.
The hardest thing in the world is to get it right, which is why scientists
spend their careers trying to do just that on the harder questions. Honor
the people who make good measurements, because they have invested much and
produced great things.
Each method has advantages and disadvantages, but it is a lucky researcher
who has a free choice. The common method in aqueous dissolution studies is
naturally aqueous optical spectrophotometry, since the sample comes prepared
as a water solution. The common method for elemental analysis of samples
which may contain indissoluble fractions and refractories is flame
spectrometry, or some kind of sputtering or ionic source mass spectrometry.
Evan, if you are doing soil studies, the flame analysis methods you describe
are good for elemental analyses. If you want to find organohalides, or some
other molecular complex, you will have to employ some other method, unless
there is a characteristic, unambiguous elemental tag. You might want to go
shopping for additional methods, but carry along a full pocketbook.
Gavin
Monona Rossol on thu 27 mar 97
Re analytical methods Gavin wrote:
>...... but carry along a full pocketbook. <
Excellent advice and good discourse on the subject.
Monona
Monona Rossol on thu 27 mar 97
Evan Dresel wrote:
> Facinating. For groundwater and soils analysis the solution is aspirated
> into either a flame (sometimes a nitrous oxide-acetylene flame for the extra
> heat) in order to form free atoms. Then a light of a characteristic
> wavelength is passed through the flame and the element in question is
> measured by atomic absorbtion of the light. More commonly these days, the
> solution is aspirated into an argon plasma (Can you say very, very hot?)
> forming free atoms which are measured by atomic emission spectrophotometry.
> So heat is most certainly involved. Perhaps you are mistaken or
> perhaps there is a method I should be looking at for trace metal analysis.<
Gavin wrote a good description of the different kinds of equipment that can
be used. However, you are right with regard to the method that FDA and
California *now* uses:
From the California Standard--whose tests are the same as the FDA federal
standards but I happened to lay hands on first:
Attachment A
3.1 Warnings shall be provided based on the result of the method of analysis
for lead set forth in "Official Mathods of Analysis of the Association of
Official Analytical Chemists," 15th Edition (1990), Method 973.32, "Cadmium
and Lead in Earthenware: Atomic Absorption Spectrophotometric Method, Final
Action, (1977), AOAC/ASTM Method ("Lead Leaching Test").
Then I went to the ASTM standard method and found:
Apparatus
4.1 *Atomic Absorption Spectometer* equipped with light sources (hollow
cathode or electrodeless discharge lamps) specific for lead and cadmium,
instrumental background correction, and a 4-in. (102-mm) single slot or
Boling burner head. Digital concentration readout may be used. Use
air-acetylene flame, instrumental background correction, and operating
conditions recommended by instrument manufacturer.
This equipment is indeed different from that which we used before. Now heat
IS involved. Air acetylene is not as "hot" as the newer equipment to which
you referred, but this test is "hot" nontheless!
Monona Rossol, industrial hygienist
Arts, Crafts and Theater Safety
181 Thompson St., # 23
New York, NY 10012-2586 212/777-0062
http://www.caseweb.com/acts/
Monona Rossol on fri 11 apr 97
Evan Dresel wrote:
> I sort of agree and sort of disagree. The EPA drinking water standards are
> a useful reference but really only give you a relative sense of the hazards.
> I use them myself as a reference for assessing the problem with contaminated
> water that no one is drinking. But I think it's worth looking at what is
> behind the standards. For drinking water the usual assumption is that a
> person consumes 20 L a day for 70 years. The cumulative dose or exposure or
> risk or however you measure the "danger" is much higher than any exposure I
> can invision from leaching of ceramics. Yes, it is good to make
> conservative assumptions, but don't forget that the drinking water standards
> **usually** make conservative assumptions so you are multiplying that by a
> large factor. <
Absolutely. And that's why what I recommend is that if the ware beats these
standards. Even the most fastidious consumer really can't complain about
these standards.
However, if a person used pottery cups, bowls, dishes, pitchers and storage
containers not only for water but all liquids and food consumed, the water
standards probably would not be sufficient.
> I don't want to spread rumors, but if I remember correctly, EPA increased
> the standard for barium from an interim value of 1 mg/L to 2 mg/L but had
> originally proposed a final standard of 4 mg/L. The 2 was a compromise --
> not exactly scientific. <
Again right. And there was also independent testimony at the time supporting
the 1 ppm standard. Life's a compromise.
The water standards are not "scientific." No government standards really
are. Look at the different federal and California standards for lead
leaching from pottery. But meeting the water standards is a good
conservative liability strategy. Any customer claiming chronic health
effects would have a very hard time convincing a jury that the potter was at
fault if her/his ware met these standards.
And let me also answer some comments from Clayarters other than you,
Evan, in this post:
Clearly the water standards attempt to protect users from *chronic* hazards.
Its amazing that some people are apparently dumb enough to think that we mean
to imply that exceeding the drinking water standards will cause people to
double up in pain with a glass of water half drunk in their hands.
**The water standards are set in an attempt to ensure that people can drink
water and maintain good health. Our pottery standards must do no less.**
Monona Rossol, industrial hygienist
Arts, Crafts and Theater Safety
181 Thompson St., # 23
New York, NY 10012-2586 212/777-0062
http://www.caseweb.com/acts/
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