Elke Blodgett on sat 8 apr 00
from Monona in response to:
> ---------- Forwarded message ----------
> Date: Thu, 6 Apr 2000 14:56:40 EDT
> From: John Baymore
> Reply-To: Ceramic Arts Discussion List
> To: CLAYART@LSV.UKY.EDU
> Subject: Re: Food safety
> Resent-Subject: RE: Food safety
>
> ----------------------------Original message----------------------------
> ------------------
> (snip)
> There are plenty of materials available that are not a problem - there was
> a list made up once - does anyone have it? I must be somewhere.
> (clip)
> Ron,
> Monona Rossol put one out a while back....... maybe she'll respond.
> BEst,
> .....................john
> John Baymore
> River Bend Pottery
> 22 Riverbend Way
> Wilton, NH 03086 USA
I can only respond if someone forwards the inquiry. Someone did.
Metals of negligible toxicity for glazes include calcium, magnesium,
potassium, and sodium. Silica also is not toxic by ingestion. So lots of
spars, and other minerals and compounds of these metals are safe to use.
Even if they leach into food, it would take a lot to reach toxic levels.
Colorants can include iron compounds. Maybe a little copper.
We haven't opened one other Pandora's box, however. All glazes contain
aluminum. And this also leaches into food. While it is clear that aluminum
is toxic at high doses, the data is confusing about lower doses. Some
people really don't want aluminum in their diets, however.
Hope this helps.
Monona Rossol
ACTS
181 Thompson St., # 23
NYC NY 10012-2586 212/777-0062
ACTSNYC@cs.com
Earl Brunner on sun 9 apr 00
I try not to get upset when I read Monona, because I know
that she
performs a valuable function in our art community.
Hopefully people are becoming more aware of the
responsiblities and precautions that they need
to have and take while working with various materials, but
ALUMINUM????
How about water and oxygen? Isn't it amazing that we live
at all?
And I mean that with all seriousness. We live in a hostile
environment.
And in universal terms a very narrow environment, couple
hundred degrees,
hight mixture of gases to breath. But ALUMINUM??? It's
everywhere!!!
>
> ----------------------------Original message----------------------------
>
>
> I can only respond if someone forwards the inquiry. Someone did.
>
> Metals of negligible toxicity for glazes include calcium, magnesium,
> potassium, and sodium. Silica also is not toxic by ingestion. So lots of
> spars, and other minerals and compounds of these metals are safe to use.
> Even if they leach into food, it would take a lot to reach toxic levels.
>
> Colorants can include iron compounds. Maybe a little copper.
>
> We haven't opened one other Pandora's box, however. All glazes contain
> aluminum. And this also leaches into food. While it is clear that aluminum
> is toxic at high doses, the data is confusing about lower doses. Some
> people really don't want aluminum in their diets, however.
>
> Hope this helps.
>
> Monona Rossol
> ACTS
> 181 Thompson St., # 23
> NYC NY 10012-2586 212/777-0062
>
> ACTSNYC@cs.com
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
Phyliss Ward on mon 10 apr 00
Actually, aluminum is suspected to be a contributing factor in Alzheimer's and
many other diseases. It is certainly not innocuous.
Earl Brunner wrote:
> ----------------------------Original message----------------------------
>
> Hopefully people are becoming more aware of the
> responsiblities and precautions that they need
> to have and take while working with various materials, but
> ALUMINUM????
> How about water and oxygen? Isn't it amazing that we live
> at all?
Diane G. Echlin on mon 10 apr 00
>
> And in universal terms a very narrow environment, couple
> hundred degrees,
> hight mixture of gases to breath. But ALUMINUM??? It's
> everywhere!!!
>
I learned on a cooking show (I think) that Aluminum pots "Breathe." That is, wh
they are heated, the pores open up, and bacteria is allowed to permeate the
surface. When the aluminum cools, the pores close, encapsulating the bacterias
and keeping them safely tucked away so they cannot be washed away. When the pot
is reheated, all those little creatures come out to play with the new food in th
pot, and the cycle begins again. Not that this has a lot to do with Aluminum in
pottery. On the other hand, when my mother was in the early to middle stages of
alzheimer's disease, her doctors were very interested in the amount of aluminum
she was exposed to through cooking pots, etc. So perhaps there is more here tha
scare tactics. I don't know. Just my penny's worth.
Di
ACTSNYC@cs.com on mon 10 apr 00
I
> ---------- Forwarded message ----------
> Date: Sun, 9 Apr 2000 20:50:47 EDT
> From: Earl Brunner
> Reply-To: Ceramic Arts Discussion List
> To: CLAYART@LSV.UKY.EDU
> Subject: Re: Monona on:Re: Food safety (fwd)
> Resent-Subject: Re: Monona on:Re: Food safety (fwd)
> ----------------------------Original message----------------------------
> I try not to get upset when I read Monona, because I know
> that she performs a valuable function in our art community.
> Hopefully people are becoming more aware of the
> responsiblities and precautions that they need
> to have and take while working with various materials, but
> ALUMINUM????
> How about water and oxygen? Isn't it amazing that we live
> at all? And I mean that with all seriousness. We live in a hostile
> environment. And in universal terms a very narrow environment, couple
> hundred degrees, hight mixture of gases to breath. But ALUMINUM??? It's
> everywhere!!!
So is silica. So is lead. So are all the metals. That's no argument at all.
But what I am concerned about most is the large number of people who now
think that Alzheimer's disease may be related to aluminum exposure. I
personally have not made up my mind about this. The fact that some
Alzheimer's victims have very high levels of aluminum in their brains could
be either the cause or the effect of the disease. It could even be unrelated.
I just don't know. I only know that aluminum at high doses is a neurotoxin
and that aluminum is a protein crosslinker--which implicates it in the aging
process.
But the people who fervently *believe* that aluminum causes Alzheimer's are a
very vocal bunch who get upset about aluminum in deodorants, in pots and
pans, etc. I have a feeling that when these people find out that aluminum
also leaches from pottery, they will be hostile. And they will
feel--somewhat rightly--that we have not been forthcoming about this fact.
This is why I am trying to find the time to get the aluminum leaching
information I have together into some useful form within this next year.
Best to head off the problem with information coming from our side.
Monona Rossol
ACTS
181 Thompson St., # 23
NYC NY 10012-2586 212/777-0062
ACTSNYC@cs.com
Gavin Stairs on tue 11 apr 00
At 03:24 PM 4/10/00, Phyliss Ward wrote:
>----------------------------Original message----------------------------
>Actually, aluminum is suspected to be a contributing factor in Alzheimer's and
>many other diseases. It is certainly not innocuous.
>
>Earl Brunner wrote:
>
> > ----------------------------Original message----------------------------
> >
> > Hopefully people are becoming more aware of the
> > responsiblities and precautions that they need
> > to have and take while working with various materials, but
> > ALUMINUM????
> > How about water and oxygen? Isn't it amazing that we live
> > at all?
The problem here is the form. We encounter Aluminum principally as Al2O3,
which is an extremely inert substance. In clay, it is also in the form of
an oxide, which we usually report as the separate oxide of Aluminum, as
above. To make Aluminum bio-available, we would have to reduce it to the
metal, hydroxide or otherwise reduce it to some metal-organic
substance. Most of the speculation concerning the role of Aluminum in such
diseases as Alzheimer's centre around the partially dissolved metal from
pots, food wraps and the like, and it use in antiperspirants (alum). I
don't think we should be concerned with the Aluminum which is one of the
central cations in our work materials. Very little of it can become
available as a poison because of the form in which we use it.
However -- you knew there was a 'however', didn't you? -- This is simply
another argument in favour of highly durable food contact surfaces. In the
most extreme cases of detergent attack, the aluminosilicate matrix of glaze
and body is attacked and dissolved. Mind you, this mostly happens in the
dishwasher, so the dissolved material does not go into food, but it does
break down the backbone of the material, and make it more likely that such
leaching into food might occur.
So a little common sense will carry us a long way here: people who ingest
powdered clay (kaolin, ball clay, etc.), which is used widely as a food
conditioner as well as a medicine, are evidently more at risk from
geological dioxins than from the Aluminum in the aluminosilicate clay
particles. In its fired form, in which extremely small amounts become free
to be ingested, the risk must be minuscule.
I'm not aware of any other forms of Aluminum in use in potting. That is,
forms in which free Aluminum is available. Unless someone else knows of
something like this, I'd say that the Aluminum alarm is a bit of an over
reaction.
Gavin
Earl Brunner on tue 11 apr 00
Fine, shut down the kilns, pack up your equipment and send
it to the
dump. (make that the hazardous waste site)
Clay: Al2O3-2SiO2-2H2O
pay particular attention to the AL2O3 part = ALUMINA
Are you saying that there is no essential difference between
ingesting
the metal aluminum and alumina as found in clay? Aluminum =
alumina?
I know that aluminum is refined from alumina, but are they
the same
thing?
That's the only form of alumina that I know of that is going
to get out
of my pots and into anything.
Because if we are talking about Alumina then we can give it
up.
I wonder what we will be eating out of next?
Probably don't need to worry about it though, most of what
we eat is
bad for us as well. If not bad for us, bad for some special
interest
group. Might as well just run down and get cremated, but
that's bad for the environment a well.
ACTSNYC@cs.com wrote:
>
> ----------------------------Original message----------------------------
> I
> > ---------- Forwarded message ----------
> > Date: Sun, 9 Apr 2000 20:50:47 EDT
> > From: Earl Brunner
> > Reply-To: Ceramic Arts Discussion List
> > To: CLAYART@LSV.UKY.EDU
> > Subject: Re: Monona on:Re: Food safety (fwd)
> > Resent-Subject: Re: Monona on:Re: Food safety (fwd)
> > ----------------------------Original message----------------------------
> >
>
> So is silica. So is lead. So are all the metals. That's no argument at all.
>
> But what I am concerned about most is the large number of people who now
> think that Alzheimer's disease may be related to aluminum exposure. I
> personally have not made up my mind about this. The fact that some
> Alzheimer's victims have very high levels of aluminum in their brains could
> be either the cause or the effect of the disease. It could even be unrelated.
> I just don't know. I only know that aluminum at high doses is a neurotoxin
> and that aluminum is a protein crosslinker--which implicates it in the aging
> process.
>
> But the people who fervently *believe* that aluminum causes Alzheimer's are a
> very vocal bunch who get upset about aluminum in deodorants, in pots and
> pans, etc. I have a feeling that when these people find out that aluminum
> also leaches from pottery, they will be hostile. And they will
> feel--somewhat rightly--that we have not been forthcoming about this fact.
>
> This is why I am trying to find the time to get the aluminum leaching
> information I have together into some useful form within this next year.
> Best to head off the problem with information coming from our side.
>
> Monona Rossol
> ACTS
> 181 Thompson St., # 23
> NYC NY 10012-2586 212/777-0062
>
> ACTSNYC@cs.com
--
Earl Brunner
http://coyote.accessnv.com/bruec
mailto:bruec@anv.net
ACTSNYC@cs.com on wed 12 apr 00
> ---------- Forwarded message ----------
> Date: Tue, 11 Apr 2000 14:49:37 EDT
> From: Gavin Stairs
> Reply-To: Ceramic Arts Discussion List
> To: CLAYART@LSV.UKY.EDU
> Subject: Re: Monona on:Re: Food safety (fwd)
> Resent-Subject: Re: Monona on:Re: Food safety (fwd)
> ----------------------------Original message----------------------------
> The problem here is the form. We encounter Aluminum principally as Al2O3,
> which is an extremely inert substance. In clay, it is also in the form of
> an oxide, which we usually report as the separate oxide of Aluminum, as
> above. To make Aluminum bio-available, we would have to reduce it to the
> metal, hydroxide or otherwise reduce it to some metal-organic
> substance. Most of the speculation concerning the role of Aluminum in such
> diseases as Alzheimer's centre around the partially dissolved metal from
> pots, food wraps and the like, and it use in antiperspirants (alum). I
> don't think we should be concerned with the Aluminum which is one of the
> central cations in our work materials. Very little of it can become
> available as a poison because of the form in which we use it.
>
> However -- you knew there was a 'however', didn't you? -- This is simply
> another argument in favour of highly durable food contact surfaces. In the
> most extreme cases of detergent attack, the aluminosilicate matrix of glaze
> and body is attacked and dissolved. Mind you, this mostly happens in the
> dishwasher, so the dissolved material does not go into food, but it does
> break down the backbone of the material, and make it more likely that such
> leaching into food might occur.
>
> So a little common sense will carry us a long way here: people who ingest
> powdered clay (kaolin, ball clay, etc.), which is used widely as a food
> conditioner as well as a medicine, are evidently more at risk from
> geological dioxins than from the Aluminum in the aluminosilicate clay
> particles. In its fired form, in which extremely small amounts become free
> to be ingested, the risk must be minuscule.
>
> I'm not aware of any other forms of Aluminum in use in potting. That is,
> forms in which free Aluminum is available. Unless someone else knows of
> something like this, I'd say that the Aluminum alarm is a bit of an over
> reaction.
> Gavin
>
You are confusing two separate hazards. Al2O3, clays, and other dusts
containing aluminum are primarily hazards because of their being inert--that
is they don't dissolve. This means if they get deep into the lungs, they
stay. And if you ingest clays or alumina, they do not dissociate and
release any significant amount of aluminum.
It is only glazes that will leach because, once fired, clays are no longer
inert minerals but a glasslike material.
I am only talking about soluble aluminum seen on leach tests and available by
ingestion. I have a bunch of these tests. They range from really high (over
100 ppm) to very low. The very high ones are from lead glazes. But many of
the glazes that pass lead tests with flying colors still leach more aluminum
than water standards would allow (0.2 ppm).
I'm not sure yet how to handle this data. I asked Dr. Ralph Sheets to do
this research and it proved what I had been saying all along. I knew that
all the ingredients of a glaze leach, so aluminum has to solublilize, too.
But now that I have the data, I can't ignore it.
Monona Rossol
ACTS
181 Thompson St., # 23
NYC NY 10012-2586 212/777-0062
ACTSNYC@cs.com
Tanya M. Tlaskal on wed 12 apr 00
Actually, this connection between aluminum and Alzheimer's is supposed to
be a fluke. I recall reading several years ago in a scientific journal that
the original observations were based on microscopic observations of brain
slices where the aluminum detected came from fixatives, mordants or stain
solutions. The connection is far from being established but the original
myth persists...
Regards,
Jorge
-----Original Message-----
From: Phyliss Ward
To: CLAYART@LSV.UKY.EDU
Date: Tuesday, April 11, 2000 06:25
Subject: Re: Monona on:Re: Food safety (fwd)
>----------------------------Original message----------------------------
>Actually, aluminum is suspected to be a contributing factor in Alzheimer's
and
>many other diseases. It is certainly not innocuous.
>
>Earl Brunner wrote:
>
>> ----------------------------Original message----------------------------
>>
>> Hopefully people are becoming more aware of the
>> responsiblities and precautions that they need
>> to have and take while working with various materials, but
>> ALUMINUM????
>> How about water and oxygen? Isn't it amazing that we live
>> at all?
>
Louis H.. Katz on thu 13 apr 00
Hi Monona,
Thanks for your vigilance in monitoring our list. But, isn't it true that glaze
is also a glass like material, or am I not understanding something? And are not
glazes as inert as clay?
Thanks
Louis
"It is only glazes that will leach because, once
fired, clays are no longer
inert minerals but a glasslike material."
--
Louis Katz
NEW EMAIL ADDRESS Louis.Katz@mail.tamucc.edu
NCECA Director of Electronic Communication and Webmaster(Ad-Hoc)
Texas A&M-CC Division of Visual and Performing Arts
Visit the NCECA World Ceramics Image Database Online
Looking for a school or a class? Visit NCECA Ceramics Educational Programs
Database Online
John Hesselberth on thu 13 apr 00
ACTSNYC@cs.com wrote:
>But many of
>the glazes that pass lead tests with flying colors still leach more aluminum
>than water standards would allow (0.2 ppm).
Hi Monona,
I am curious why you continue to feel so strongly that drinking water
standards are the standard to be met. This is so much more stringent
than the standard for lead which, as I think you know, is 7-300 times the
drinking water standard depending on the type of vessel and whether you
are in California or the rest of the U.S. Do you have some data which
support your point of view. If so, I would sure like to see the
reference to it. Is this merely an absolute-safe-side,
let's-live-in-fear-of-the-lawyers view or is there more substance to your
continual reference to drinking water? From what I have seen I could
make a very strong a case for ratioing off the lead standards given that
the water standards probably already take into account the toxicity
difference between materials.
On a related subject, I have recently done, with Roland Hale, some
limited testing of actual foods in a glaze that has fairly poor leaching
performance (we purposefully picked a poor one) and compared it to the
standard leaching test. The standard leaching test is a very rigorous
test--much more rigorous than anything found in "normal" use except
perhaps cooking a tomato-based casserole in an oven. Even orange juice
left in a cup for 24 hours at room temperature only leaches about 30-35%
of the amount obtained in the standard leaching test. Orange juice
stored in a refrigerator would give significantly less leaching than
that. Coffee (which is also quite acidic) poured in hot and left for an
hour leaches only about 3-12% of the amount leached in the standard
leaching test. While some coffee undoubtedly sits in a cup for quite a
while by far the greatest amount is consumed within 20 minutes so even
the above 1 hour test is at the outer limits of what would be seen in
normal use.
As you know, I have been working to understand how to make glazes more
stable and will continue to do that; however I want to work toward
objective, not arbitrary, goals. For example in the case of copper,
there are quite a number of glazes out there that will leach in the range
of 15-50 mg/l of copper in the standard leaching test. I have come to
believe that a reasonable goal is <10 mg/l largely because this is where
copper begins to make food taste bitter. Given that the leaching test is
more rigorous than almost any normal use of pottery would give, this
means we will be unlikely to affect the taste of food if we stay <10. In
reality 90+% (and probably 99+%) of the time, at <10 mg/l, we would not
expose a person to any higher level of copper than is allowed in drinking
water. 10 mg/l also happens to be about 7-8 times the water standard for
copper which puts it at the extremely conservative end of the range when
ratioing off the lead range of 7-300. I now know that attractive medium
green glazes can be made that leach less than 10 mg/l; although early in
my work I did not know if that would be possible. If you have other data
or can suggest a more objective way to set a goal I'd like to hear it.
Also, if you feel my logic for setting the copper goal is sound, can you
point me to ways to set objective goals for other leachates?
On the other hand, if you continue to believe that the water limits
should be the standard then I believe you have a strong obligation to
take on the lead-glazed dinnerware industry as a first priority and get
their standards brought down to water levels. They have the potential to
harm far more people than studio potters if water standards represent the
safe limit.
Yours for stable glazes, John
John Hesselberth
Frog Pond Pottery
P.O. Box 88
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
The only things in life that are certain are death and taxes; however
only taxes come once a year. Anonymous
Ray Aldridge on thu 13 apr 00
At 04:37 PM 4/12/00 EDT, you wrote:
>You are confusing two separate hazards. Al2O3, clays, and other dusts
>containing aluminum are primarily hazards because of their being inert--that
>is they don't dissolve. This means if they get deep into the lungs, they
>stay. And if you ingest clays or alumina, they do not dissociate and
>release any significant amount of aluminum.
>
>It is only glazes that will leach because, once fired, clays are no longer
>inert minerals but a glasslike material.
>
>I am only talking about soluble aluminum seen on leach tests and available by
>ingestion. I have a bunch of these tests.
May I ask where you got them, and why these glazes were tested for aluminum
solubility?
And could you tell us in what form the aluminum is found in the leachate,
and what the methodology used to test these samples was?
Ray
Aldridge Porcelain and Stoneware
http://www.goodpots.com
ferenc jakab on fri 14 apr 00
> But what I am concerned about most is the large number of people who now
> think that Alzheimer's disease may be related to aluminum exposure. I
Monona,
Your expertise in this field is of course far superior to mine. I understand
that the original spark for concern about Altzheimers was from the
neurotoxic effect it had in cats, ( human brains are not effected in the
same way) and that the jury is still well and truly out on this one.
Feri
ACTSNYC@cs.com on fri 14 apr 00
> ---------- Forwarded message ----------
> Date: Thu, 13 Apr 2000 13:15:27 EDT
> From: "Louis H.. Katz"
> To: CLAYART@LSV.UKY.EDU
> Subject: Re: Monona on:Re: Food safety (fwd)
> Resent-Subject: Re: Monona on:Re: Food safety (fwd)
> ----------------------------Original message----------------------------
> Hi Monona,
> Thanks for your vigilance in monitoring our list. But, isn't it true that
> glaze is also a glass like material, or am I not understanding something?
> And are not glazes as inert as clay?
> Thanks
> Louis
> --
>
No. They are not as inert. The theory that they were is what caused people
to believe that frits were acid insoluble and inert. Now we've put that to
rest. Glass is sort of a mishmash of molecules frozen together in a mass.
The composition is not even consistent. Glass is very vulnerable to
dissolution. Lead crystal leaches lead into food. Other types of glass
containers leach other metals. Glazes are doing the same thing.
Clay is a crystalline mineral in which the molecules are organized in a
pattern and strongly held. Not all crystalline materials are inert--but
clays really are about as inert as you can get.
You might want to look at the post on ClayArt I just wrote on aluminum in
medications. The FDA says that one of the sources of contamination if from
the glass containers the liquid medications are in.
I hope this explains it. If not, ask again!
Monona
ACTSNYC@cs.com on fri 14 apr 00
> -------- Forwarded message ----------
> Date: Thu, 13 Apr 2000 13:21:41 EDT
> From: Ray Aldridge
> Reply-To: Ceramic Arts Discussion List
> To: CLAYART@LSV.UKY.EDU
> Subject: Re: Monona on:Re: Food safety (fwd)
> Resent-Subject: Re: Monona on:Re: Food safety (fwd)
> ----------------------------Original message----------------------------
> At 04:37 PM 4/12/00 EDT, you wrote:
> >You are confusing two separate hazards. Al2O3, clays, and other dusts
> >containing aluminum are primarily hazards because of their being inert--
> that
> >is they don't dissolve. This means if they get deep into the lungs, they
> >stay. And if you ingest clays or alumina, they do not dissociate and
> >release any significant amount of aluminum.
> >
> >It is only glazes that will leach because, once fired, clays are no longer
> >inert minerals but a glasslike material.
> >
> >I am only talking about soluble aluminum seen on leach tests and
available
> by
> >ingestion. I have a bunch of these tests.
>
> May I ask where you got them, and why these glazes were tested for aluminum
> solubility? <
Dr. Ralph W. Sheets at Southwest Missouri State University. I asked him to
test for aluminum because I was sure it would be found and wanted proof.
>
> And could you tell us in what form the aluminum is found in the leachate,<
Since it was clearly solubilized by the acetic acid, I'd guess it is probably
in the form of aluminum acetate or aluminum subacetate.
> and what the methodology used to test these samples was? <
The standard FDA leach test.
>
> Ray
>
> Aldridge Porcelain and Stoneware
> http://www.goodpots.com
>
>
ACTSNYC@cs.com on fri 14 apr 00
>
> ---------- Forwarded message ----------
> Date: Thu, 13 Apr 2000 13:17:20 EDT
> From: John Hesselberth
> Reply-To: Ceramic Arts Discussion List
> To: CLAYART@LSV.UKY.EDU
> Subject: Re: Monona on:Re: Food safety (fwd)
> Resent-Subject: Re: Monona on:Re: Food safety (fwd)
> ----------------------------Original message----------------------------
> ACTSNYC@cs.com wrote:
>
> I am curious why you continue to feel so strongly that drinking water
> standards are the standard to be met. This is so much more stringent
> than the standard for lead which, as I think you know, is 7-300 times the
> drinking water standard depending on the type of vessel and whether you
> are in California or the rest of the U.S. <
The FDA and even the California standard for lead leaching is a compromise
with what is possible Vs what is desirable. Don't base any calculations on
the difference between the water standards and the ceramic leach standards
for lead. They are skewed in order not to put the ceramic and glass
industries out of business.
Even more interesting, the FDA's maximum contaminant level goal (MCLG) for
lead in water is ZERO!
> Do you have some data which
> support your point of view. If so, I would sure like to see the
> reference to it. Is this merely an absolute-safe-side,
> let's-live-in-fear-of-the-lawyers view or is there more substance to your
> continual reference to drinking water? From what I have seen I could
> make a very strong a case for ratioing off the lead standards given that
> the water standards probably already take into account the toxicity
> difference between materials. <
Since there are no ceramic leaching standards for metals other than lead and
cadmium, the water standards are kind of handy. Its not perfect toxicology
to use them this way, but pretty practical. Remember that the water
standards are, for the most part, the standards for the worst quality water.
If your water just barely passes the MCLs, I suggest you buy bottled! I
think a person drinking out of a ceramic cup probably should be able to
expect that they would not be exposed to more stuff than in a glass of
really poor quality municipal water.
> On a related subject, I have recently done, with Roland Hale, some
> limited testing of actual foods in a glaze that has fairly poor leaching
> performance (we purposefully picked a poor one) and compared it to the
> standard leaching test. The standard leaching test is a very rigorous
> test--much more rigorous than anything found in "normal" use except
> perhaps cooking a tomato-based casserole in an oven. Even orange juice
> left in a cup for 24 hours at room temperature only leaches about 30-35%
> of the amount obtained in the standard leaching test. Orange juice
> stored in a refrigerator would give significantly less leaching than
> that. Coffee (which is also quite acidic) poured in hot and left for an
> hour leaches only about 3-12% of the amount leached in the standard
> leaching test. While some coffee undoubtedly sits in a cup for quite a
> while by far the greatest amount is consumed within 20 minutes so even
> the above 1 hour test is at the outer limits of what would be seen in
> normal use. <
I suggest you don't even go there. The rationale for the FDA leach tests is
all spelled out in detail. Get the standards and read them. There are
mathematical relationships between the leach test and safety factors with
foods. Remember, some glazes actually leach more with alkaline foods than
with acid. There are too many variables with actual food. You may get
less---and you may get more--leaching with actual food.
> As you know, I have been working to understand how to make glazes more
> stable and will continue to do that; however I want to work toward
> objective, not arbitrary, goals. For example in the case of copper,
> there are quite a number of glazes out there that will leach in the range
> of 15-50 mg/l of copper in the standard leaching test. I have come to
> believe that a reasonable goal is <10 mg/l largely because this is where
> copper begins to make food taste bitter. Given that the leaching test is
> more rigorous than almost any normal use of pottery would give, this
> means we will be unlikely to affect the taste of food if we stay <10. In
> reality 90+% (and probably 99+%) of the time, at <10 mg/l, we would not
> expose a person to any higher level of copper than is allowed in drinking
> water. 10 mg/l also happens to be about 7-8 times the water standard for
> copper which puts it at the extremely conservative end of the range when
> ratioing off the lead range of 7-300. I now know that attractive medium
> green glazes can be made that leach less than 10 mg/l; although early in
> my work I did not know if that would be possible. If you have other data
> or can suggest a more objective way to set a goal I'd like to hear it. <
I'm just not going to spend time on something that has already been done.
There are standards for how much is too much. And these are determined by
complex toxicological profiles taking into account all the different types of
people in the general population. You can't make up your mind on the basis
of taste. That's just nuts.
> Also, if you feel my logic for setting the copper goal is sound, can you
> point me to ways to set objective goals for other leachates? <
I don't think the logic is sound. FDA says:
" ...people who drink water containing copper in excess of the action level
over a relatively short amount of time could experience gastrointestinal
distress. Some people who drink water containing copper in excess of the
action level over many years could suffer liver or kidney damage. People
with Wilson's Disease should consult their personal doctor." 63 FR 44534
I have a sister with Wilson's Disease and the water quality standards are not
protective enough for people like this. But a person should be able to use
our ware for years without risking health effects.
> On the other hand, if you continue to believe that the water limits
> should be the standard then I believe you have a strong obligation to
> take on the lead-glazed dinnerware industry as a first priority and get
> their standards brought down to water levels. They have the potential to
> harm far more people than studio potters if water standards represent the
> safe limit. <
Exactly my plan. In 1989, FDA stated that they were aware that metals other
than lead and cadmium were a problem in ceramics and they called for comments
about setting standards for other metals. I think I was about the only
commenter! There was almost no data to report so nothing was done.
But as the data builds up, there will be more to say. Then I will go back
and petition FDA requesting them to set leach standards for other metals that
are specifically for ceramics. Until that time, I will use the water
standards. There is nothing currently that is better.
Hope this explains it.
Monona
ACTS
181 Thompson St., # 23
NYC NY 10012-2586 212/777-0062
ACTSNYC@cs.com
Evan Dresel on fri 14 apr 00
The aluminum drinking water standard is a secondary standard which means
it is not health-based. From the United States EPA website
http://www.epa.gov/safewater/mcl.html :
National Secondary Drinking Water Regulations (NSDWRs or secondary
standards) are
non-enforceable guidelines regulating contaminants that may
cause cosmetic effects (such as
skin or tooth discoloration) or aesthetic effects (such as
taste, odor, or color) in drinking water.
EPA recommends secondary standards to water systems but does
not require systems to
comply. However, states may choose to adopt them as
enforceable standards. See Table 2.
Actually the EPA gives a range of values for aluminum 0.05 to 0.2 mg/L.
I'm not familiar with the reason for this. As many of you know, I don't
believe that drinking water standards are appropriate levels to use for
leach tests. But using secondary standards really doesn't make sense if
you are worried about health risks.
BTW: aluminum can be quite soluble at high and low pH, depending what
else is present in solution, but is extremely insoluble at near neutral
pH. If I see any detectable aluminum in groundwater samples it usually
means that the filter failed.
-- Evan in W. Richland WA who saw a curlew today.
ACTSNYC@cs.com wrote:
>
> ----------------------------Original message----------------------------
snip...
> I am only talking about soluble aluminum seen on leach tests and available by
> ingestion. I have a bunch of these tests. They range from really high (over
> 100 ppm) to very low. The very high ones are from lead glazes. But many of
> the glazes that pass lead tests with flying colors still leach more aluminum
> than water standards would allow (0.2 ppm).
>
> I'm not sure yet how to handle this data. I asked Dr. Ralph Sheets to do
> this research and it proved what I had been saying all along. I knew that
> all the ingredients of a glaze leach, so aluminum has to solublilize, too.
> But now that I have the data, I can't ignore it.
>
> Monona Rossol
> ACTS
> 181 Thompson St., # 23
> NYC NY 10012-2586 212/777-0062
>
> ACTSNYC@cs.com
ACTSNYC@cs.com on sat 15 apr 00
In a message dated 4/14/00 2:40:39 PM Eastern Daylight Time,
eiblodge@freenet.edmonton.ab.ca writes:
>
> > But what I am concerned about most is the large number of people who now
> > think that Alzheimer's disease may be related to aluminum exposure. I
>
> Monona,
> Your expertise in this field is of course far superior to mine. I
understand
> that the original spark for concern about Altzheimers was from the
> neurotoxic effect it had in cats, ( human brains are not effected in the
> same way) and that the jury is still well and truly out on this one.
> Feri
Nah. The data I've looked at is all on human brains and nervous systems.
But I agree that the jury is still out. As I keep saying, the only
conclusion I've come to is there isn't enough data to draw any conclusion.
Monona
ACTS
181 Thompson St., # 23
NYC NY 10012-2586 212/777-0062
ACTSNYC@cs.com
Tom Wirt/Betsy Price on sat 15 apr 00
----- Original Message -----
From: John Hesselberth
Subject: Re: Monona on:Re: Food safety (fwd)
> ----------------------------Original message----------------------------
> ACTSNYC@cs.com wrote:
> I am curious why you continue to feel so strongly that drinking water
> standards are the standard to be met. This is so much more stringent
> than the standard for lead which, as I think you know, is 7-300 times the
> drinking water standard depending on the type of vessel and whether you
> are in California or the rest of the U.S. Do you have some data which
> support your point of view. If so, I would sure like to see the
John
I've got to suspect that the water standards were developed on the
assumption that someone might drink the recommended 64 ounces per day,
everyday from the same source, plus whatever else might be used in cooking
or washing.
The difficulty I see in using water standards is just that. Not many of us
drink 64 ounces of vinegar that has been standing in a bowl for 24
hours....or even orange juice.
So to me, the idea of using a water as a standard is, as you suggest,
nonsense.
Tom Wirt
John Hesselberth on sun 16 apr 00
Monona Rossol wrote:
>
>The FDA and even the California standard for lead leaching is a compromise
>with what is possible Vs what is desirable. Don't base any calculations on
>the difference between the water standards and the ceramic leach standards
>for lead. They are skewed in order not to put the ceramic and glass
>industries out of business.
>
>
>I suggest you don't even go there. The rationale for the FDA leach tests is
>all spelled out in detail. Get the standards and read them. There are
>mathematical relationships between the leach test and safety factors with
>foods. Remember, some glazes actually leach more with alkaline foods that
>with acid. There are too many variables with actual food. You may get
>less---and you may get more--leaching with actual food.
Hmmm. So which is is? Are the leaching test and resulting standards a
compromise or is the rationale spelled out in detail? You can't have
both sides of this argument--at least not in the same memo. I have read
CPG 7117.07 and CPG 7117.08 and there is not a thing in those documents
about rationale. Can you give me a specific reference? As you know, the
FDA records are pretty difficult to search without a starting point.
Also there are very, very few alkaline foods. The FDA has an excellent
list of the pH of foods on their web site you might find useful. I found
it at http://vm.cfsan.fda.gov/~mow/app3a.html. They list maybe 150
different foods and crackers, cakes, some cheeses, milk part of the time
(its range is from 6.3-8.5) and egg whites are about the only alkaline
ones. Probably less than 5% of the total foods listed are alkaline.
>
You can't make up your
>mind on the basis of taste. That's just nuts.
You said in an earlier post that the aluminum standard for drinking water
of 0.2 mg/l was set primarily on the basis of taste. I am concerned that
you are taking whichever side of this argument serves your purpose at the
moment. If setting a standard or goal on the basis of taste is "just
nuts" then using that standard as the basis for food safety or regulating
a piece of pottery out of existence is "just nuts" too.
>
>" ...people who drink water containing copper in excess of the action level
>over a relatively short amount of time could experience gastrointestinal
>distress. Some people who drink water containing copper in excess of the
>action level over many years could suffer liver or kidney damage. People
>with Wilson's Disease should consult their personal doctor." 63 FR 44534
>
I'll look it up and read the whole document. Thanks for the specific
reference.
>
>
>Exactly my plan. In 1989, FDA stated that they were aware that metals other
>than lead and cadmium were a problem in ceramics and they called for
>comments
>about setting standards for other metals. I think I was about the only
>commenter! There was almost no data to report so nothing was done.
>
>But as the data builds up, there will be more to say. Then I will go back
>and petition FDA requesting them to set leach standards for other metals
>that
>are specifically for ceramics. Until that time, I will use the water
>standards. There is nothing currently that is better.
>
But of course, nothing to justify it either except, as you stated earlier
in this post "the water standards are kind of handy". I remained
concerned about the nearly complete lack of science in this area and
standards being proposed or set with no hard data to back them up. While
I don't like to use this argument because it is specious and sounds too
much like the tobacco industry I am prompted, by the specious nature of
your arguments, to point out that there is not a single documented
instance of anyone having been harmed by leaching from a lead-free
ceramic glaze--not one. If you get to use specious arguments, I do too.
Meanwhile, I'm going to go mix up some stable glazes. I remain committed
to learning how to make glazes more stable; however I want goals to work
toward that make sense. When the lead standards for glazes are so far
above the lead standards for water I find it impossible to rationalize
that the water standards are what should be used for other
materials--talk about just plain nuts (to borrow one of your favorite
putdowns)! So far I don't have sensible goals. Think I'll test some
glazes for aluminum too.
John Hesselberth
Frog Pond Pottery
P.O. Box 88
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
The only things in life that are certain are death and taxes; however
only taxes come once a year. Anonymous
ACTSNYC@cs.com on mon 17 apr 00
> ---------- Forwarded message ----------
> Date: Sun, 16 Apr 2000 18:03:35 EDT
> From: John Hesselberth
> Reply-To: Ceramic Arts Discussion List
> To: CLAYART@LSV.UKY.EDU
> Subject: Re: Monona on:Re: Food safety (fwd)
> Resent-Subject: Re: Monona on:Re: Food safety (fwd)
> ----------------------------Original message----------------------------n
a message dated 4/15/00 7:36:51 AM Eastern Daylight Time,
john@frogpondpottery.com writes:
Monona Rossol wrote:
> >The FDA and even the California standard for lead leaching is a
compromise
> >with what is possible Vs what is desirable. Don't base any calculations
on
> >the difference between the water standards and the ceramic leach
standards
> >for lead. They are skewed in order not to put the ceramic and glass
> >industries out of business.
> >
> >
> >I suggest you don't even go there. The rationale for the FDA leach tests
> is all spelled out in detail. Get the standards and read them. There are
> >mathematical relationships between the leach test and safety factors with
> >foods. Remember, some glazes actually leach more with alkaline foods
that
> >with acid. There are too many variables with actual food. You may get
> >less---and you may get more--leaching with actual food.
>
> Hmmm. So which is is? Are the leaching test and resulting standards a
> compromise or is the rationale spelled out in detail? <
Both, of course--as with ALL regulations. Do you think one side gets
everything they want even if they know it's right? Welcome to reality.
You are deliberately being obtuse now. This is not a reasonable comment on
your part.
> You can't have
> both sides of this argument--at least not in the same memo. I have read
> CPG 7117.07 and CPG 7117.08 and there is not a thing in those documents
> about rationale. Can you give me a specific reference? As you know, the
> FDA records are pretty difficult to search without a starting point. <
You need the standard's prerule material in which the toxicology rationale
for setting the limit is proposed FDA, industry comments or argues, and FDA
replies. That's where the studies all are and the reasons for the decision
are made. And it's no memo. Its a ton of stuff, especially if you go to the
references as well.
I understand all this background stuff is available on the web, but I don't
know how to do that. I get the daily Federal Register and read it as it
comes out. Its also all available in any governmental or law library. And
the Register is very well indexed.
If you are going to presume to set your own standards for leaching, you
bloody well better know what wiser heads than yours have come up with in the
past and why.
> Also there are very, very few alkaline foods. The FDA has an excellent
> list of the pH of foods on their web site you might find useful. I found
> it at http://vm.cfsan.fda.gov/~mow/app3a.html. They list maybe 150
> different foods and crackers, cakes, some cheeses, milk part of the time
> (its range is from 6.3-8.5) and egg whites are about the only alkaline
> ones. Probably less than 5% of the total foods listed are alkaline.
>
So? That's why its better to test in acid, even though in some cases the
amount of leaching will underestimate leaching into the alkaline foods. You
aren't thinking clearly. The fact that there are fewer alkaline foods than
acid isn't relevant.
>
> You can't make up your
> >mind on the basis of taste. That's just nuts.
>
> You said in an earlier post that the aluminum standard for drinking water
> of 0.2 mg/l was set primarily on the basis of taste. <
I made that comment in response to your proposed, personally-evolved,
standard for copper for which your rationale relies in part on your detecting
a bitter taste.
There are substances whose taste can be detected at levels below concern and
others that by the time you taste them you are in trouble. That's why one or
two of the water standards are set to avoid a bad taste while the others are
set for toxicity. That doesn't mean that the one that tastes bad is not
also toxic at slightly higher levels. I think you are bright enough to know
that, and I'm not interested in arguments for the sake of arguing.
I've come to a decision: I spend a lot of time training and teaching and
love to explain stuff on ClayArt, but the arguments in this post are going
nowhere. I am going to summarize what I have been saying in these posts
one, AND I DO MEAN ONE, more time. And then I'm only going to respond to
real questions.
1. As I have said all along in these posts: I DON'T THINK THAT ALUMINUM IS A
BIG TOXIC PROBLEM FOR POTTERS. Aluminum is by far less toxic than so many of
the other metals we use. It may or may not be related to Alzheimer's, ALS
and other diseases. But aluminum definitely is toxic at high levels and some
individuals are exquisitely susceptible to aluminum.
2. We need to assess aluminum leaching with some test data to quantify the
problem and to look for glazes that do not leach much aluminum. Actually,
this should be easier than with many of the more toxic metals.
3. We need to be open about the fact that ALL elements in a glaze leach.
The whole glaze is dissolving. By failing to understand the nature of
leaching and by pretending that aluminum doesn't leach we will only engender
some well-earned distrust from our customers.
4. We need to know which populations are particularly susceptible to
aluminum leaching, such as people with kidney problems and infants, so we can
make intelligent suggestions to our customers.
5. We need to inform those people that do not want any additional aluminum in
their diets since they have a right to know. This is the same as the problem
with milk from hormone injected cows. Even though many experts are sure
there will be no adverse effects from the milk, people should have the right
to know which foods are made with this milk so they can make up their own
minds.
6. While a panel of toxicologists could come up with better standards for
ceramic leaching--and almost surely will one day, at present the best
solution is to use the EPA water quality standards as guides. People today
are buying bottled water so they can drink less polluted water than that
which is available in cities whose water barely passes these standards. So
in general, I think we should not be responsible for exposing people,
without their knowledge, to food and drink which may contain pollutants at
levels above what would be allowed by EPA in a rather bad municipal water
supply. It's not great toxicology, but it is common sense.
Monona Rossol
ACTS
181 Thompson St., # 23
NYC NY 10012-2586
ACTSNYC@cs.com
John Hesselberth on tue 18 apr 00
ACTSNYC@cs.com wrote:
>I've come to a decision: I spend a lot of time training and teaching and
>love to explain stuff on ClayArt, but the arguments in this post are going
>nowhere. I am going to summarize what I have been saying in these posts
>one, AND I DO MEAN ONE, more time. And then I'm only going to respond to
>real questions.
I also have decided not to pursue this any further. It is no longer
productive and, besides, I've learned what I need to know. I could argue
with many of the points in your last response because there is a lot
there that should be cleared up. But that would serve little purpose.
What I hoped for in asking my initial question was some open, objective
discussion of the pros and cons of various goals for leaching. I offered
an alternative view of the way one might think about setting goals for
glaze leaching and wanted to know your thoughts.
What I first got back was primarily a tirade of insults and inconsistent
statements. When I confronted those inconsistent statements what I got
back was (in the public version) some thoughtful response coupled with a
continuing string of attempted put-downs and (in the private version)
another tirade and stronger insults. Your outbursts don't intimidate me
Monona; actually I find them revealing and, therefore, helpful. The only
times, during a long career of supervising literally hundreds of highly
trained technical people, that I have seen such a defensive and vitriolic
reaction, to what I had hoped would be an objective discussion, is when I
have caught someone peddling an unsupportable position.
I am disappointed though. I had hoped you might be an ally in setting
reasonable, meaningful guidelines or goals for glaze leaching
research--someone with an open mind to bounce ideas off of. I now know
that will not be possible; it's clear to me you don't work in that mode.
That's OK; now that I know that, I will seek out other people to help me.
John Hesselberth
Frog Pond Pottery
P.O. Box 88
Pocopson, PA 19366 USA
EMail: john@frogpondpottery.com web site: http://www.frogpondpottery.com
"Pots, like other forms of art, are human expressions: pleasure, pain or
indifference before them depends upon their natures, and their natures
are inevitably projections of the minds of their creators." Bernard
Leach, A Potter's Book.
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