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Tuckerfan
01-02-2007, 05:46 AM
A poster on another board I frequent is thinking about getting tungsten carbide wedding rings is a bit concerned about the rings shattering easily and wants to know what kind of alloy they should look for in a ring. All I know about tungsten carbide alloys is that some of them are nearly indestructible and others are not, but I've no idea which alloy is which. Any recommendations?

Also, there's a wide variation in prices on websites for rings of the same style. One site will sell a ring for $50, while another site has an identical ring for $250. Any idea as to what could be causing the disparity in prices?

Swarf&Sparks
01-02-2007, 09:36 AM
Maybe better look at titanium alloys?
G11 Ti is commonly used in jewellery, anodizes in some magnificent peacock colours.
Rgds, Lin

SGW
01-02-2007, 10:05 AM
Just out of curiosity, and not to disparage anyone's personal whims...but why would anyone want a tungsten carbide wedding ring?

Evan
01-02-2007, 10:09 AM
Tell him to forget it. Tungsten carbide alloys are cemented alloys using cobalt as a binder. Cobalt is highly toxic.

topct
01-02-2007, 10:26 AM
Just out of curiosity, and not to disparage anyone's personal whims...but why would anyone want a tungsten carbide wedding ring?

For one of these lovely ladies.

http://www.yesbutnobutyes.com/archives/2006/01/the_top_ten_sex.html

Swarf&Sparks
01-02-2007, 10:30 AM
Kinda my point, in a gentle way Evan.
Maybe mistook W for Ti?
Don't think pure tungsten is toxic (?) but cemented carbides certainly are.
Dunno why you'd want a tungsten ring either. There are much denser metals.
Uranium, plutonium........ :D

BTW, hope retirement brings you joy and peace.
Rgds, Lin

Evan
01-02-2007, 10:33 AM
Tungsten is actually slightly denser than uranium. Still, what's wrong with platinum?

SGW
01-02-2007, 10:36 AM
I just did a quick web search for "tungsten carbide ring." Allegedly, they use a tungsten carbide alloy that doesn't contain cobalt. At least some of them claim to.
It sure wouldn't be my thing. I see no artistry in them, but I guess there is no accounting for taste.

Swarf&Sparks
01-02-2007, 10:48 AM
Nuthin at all wrong with platinum. Even in today's market, it's still gotta be cheaper than plutonium.
Mind you, if it's a question of density, Pb at 82, Pt at 78? :D

Scishopguy
01-02-2007, 12:39 PM
A couple of my wife's friends had a pair made out of meteorite material. Whatever floats your boat, I guess.

If either partner is suspected of "getting around" you could make them out of brass. Even if they took it off the green stain would be a dead giveaway.

Swarf&Sparks
01-02-2007, 12:45 PM
Hell, pretty soon the wedding ceremony will include a vet with a "chip" needle :D

Tuckerfan
01-02-2007, 12:58 PM
Just out of curiosity, and not to disparage anyone's personal whims...but why would anyone want a tungsten carbide wedding ring?
A.) It's cheap. B.) It's tough as all get out and they're rough on jewelry C.) They're heavier than titanium, and thus they know when they've got it on and it hasn't slipped off.

So, I guess I'll tell them that Henny Youngman's not happy with their choice.

hitnmiss
01-02-2007, 01:59 PM
I machined mine out of 303. Held up pretty good, course 2.8 years later I don't need it anymore...

lazlo
01-02-2007, 02:30 PM
Tell him to forget it. Tungsten carbide alloys are cemented alloys using cobalt as a binder. Cobalt is highly toxic.Uh, no.

Tungsten carbide wedding rings are very trendy these days.

http://www.oromi.com/cat_wrbo/cat_display.php?categoryname=Tungsten+Wedding+Ring s
http://www.e-weddingbands.com/store/tungsten_rings.html
http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=230072615144


Where did you get the idea that cobalt was toxic? Cobalt is an essential element in humans, as a constituent of vitamin B12.

http://www.epa.gov/ttnatw01/hlthef/cobalt.html

Human studies are inconclusive regarding inhalation exposure to cobalt and cancer, and the one available oral study did not report a correlation between cobalt in the drinking water and cancer deaths. EPA has not classified cobalt for carcinogenicity.

SGW
01-02-2007, 02:38 PM
See http://www.cdc.gov/niosh/npg/npgd0647.html

Rich Carlstedt
01-02-2007, 02:39 PM
Carbide without Cobalt, is like steel without carbon.

Cobalt is in my artificial hip right now (Chrome/Cobalt) so how can it be carcinogenic Evan ?
FDA would not permit it !

As long as the atoms are bonded(locked) it is OK to my knowledge
Rich

The following is a copy of http://www.hipsandknees.com/hip/hipimplants.htm
"The metal parts of the implant are manufactured of Cobalt-chrome or Titanium. There is no agreement as to which is better. In some circumstances, each has advantages over the other. Cobalt-chrome has been used in the manufacture of orthopedic implants for 65 years, and is extremely well tolerated by the body. The AML stem is made of Cobalt-chrome. The socket is made of Titanium. In rare cases patients with metal allergies may have skin rashes, or chronic pain and swelling of the replaced joint which may be due to metal allergy. True rejection of the implant has never been reported"

lazlo
01-02-2007, 03:00 PM
See http://www.cdc.gov/niosh/npg/npgd0647.html

Sure, if you're grinding tungsten carbide, you don't want to get it into your lungs, but we're talking about wearing tungsten carbide alloy.

Evan
01-02-2007, 04:28 PM
I didn't say cobalt is carcinogenic, I said it is toxic. Big difference although it may also promote tumor growth, not the same as causing it.

Sure vitamin B12 contains cobalt as cobalamin. The RDA is one to two millionths of a gram. In larger doses or in doses that are highly localized it is toxic. The same effect is found with many metals such as selenium.

In this case the use of a material containing cobalt in proximity to the skin is the concern. That is the most common cause of problems with cobalt.



Toxicity

Cobalt and its salts are relatively non toxic by ingestion. Most cases
of cobalt toxicity relate to occupational skin contact or inhalation.

Features

Topical

- Cobalt is a topical irritant and a well recognised cause of
occupational contact dermatitis.
- Cobalt sensitivity may be the cause of metal prosthesis
failure.
- Simultaneous allergies to nickel and cobalt are frequent.
- Orofacial granulomatosis has been described in association
with delayed cobalt hypersensitivity.

http://www.intox.org/databank/documents/chemical/cobalt/ukpid52.htm

lazlo
01-02-2007, 04:47 PM
I didn't say cobalt is carcinogenic, I said it is toxic.

Evan, you worry too much. The British article you Googled says that cobalt is hypoallegenic to some people:

"Toxicity

Cobalt and its salts are relatively non toxic by ingestion. Most cases of cobalt toxicity relate to occupational skin contact or inhalation."

There are millions of people around the world wearing tungsten carbide wedding rings, and they're not developing tumors.

Some people are allergic to just about every metal used in jewelry except gold. And some of the tungsten carbide wedding rings are alloyed with nickel instead of cobalt. Some people are allergic to nickel (or silver, or...).

Titanium and Tungsten wedding rings comparison
http://www.titaniumkay.com/titanium-tungsten.aspx

"Both titanium and tungsten are considered "model metals" in the jewelry industry because they were not available to the consumer market as commodities until ten years ago. They have gained tremendous popularity since the introduction and become an integral part of the jewelry material spectrum.

Due to the rather little exposure, many questions arise concerning titanium and tungsten when it comes to choosing jewelry. The followings are some points of consideration if you are seriously thinking about buying a titanium or tungsten wedding ring.

...
Hypoallergenic

This is the very same concern as buying silver jewelry to some people: Will I be allergic to the jewelry? In general, titanium jewelry is virtually safe to wear for everybody. Yet, some tungsten carbide jewelry contains the element cobalt that some people are allergic to. Interesting, another form of tungsten alloy using nickel as a binder metal is hypoallergenic, even to people who are allergic to nickel."

Evan
01-02-2007, 05:05 PM
There are millions of people around the world wearing tungsten carbide wedding rings, and they're not developing tumors.
So what? Why do you persist in referring to tumors? I never said it is carcinogenic and that is not the same as toxic. Stop trying to throw a red herring in the discussion.

Skin reactions to nickel and cobalt are very common and it most certainly isn't a good idea to buy or make a wedding ring from a material that contains either.

Joel
01-02-2007, 05:48 PM
Toxic = poisonous. Poisonous = a substance causing illness or death when eaten, drunk, or absorbed, even in relatively small quantities (from Websters).

I would imagine that the statement “Cobalt is highly toxic” lent to the apparent confusion. Of course carcinogenic has a different, quite specific meaning.

A skin reaction is not typically very problematic, nor much of a risk. Irritant = causing inflammation - perhaps this is more appropriate and just a bit less dire.

lazlo
01-02-2007, 06:19 PM
So what? Why do you persist in referring to tumors?

Evan, you're the one who brought up tumors! :)


I said it is toxic. Big difference although it may also promote tumor growth

The poor guy is asking a simple question about what to look for in tungsten wedding rings, and you're trying to get him all worked up about tumors. :rolleyes:

Tucker: I would imagine the difference in price, and the durability of the ring has to do with the actual tungsten content.

One really nice advantage to tungsten wedding rings is that they will stay highly polished. Anyone who's been married knows that their gold or platinum wedding band starts out really shiny, but quickly dulls and nicks. My wedding band is gold with a platinum band in the middle, and I caught it on a knurl a week after we came back from our honeymoon, causing a good-sized ding. My Wife was very unhappy.

There's probably an important metaphor in there somewhere ;)

Evan
01-02-2007, 06:28 PM
Depending on the type of exposure cobalt can be highly toxic. The occupational exposure limits in air are <50 micrograms per cubic meter.

Incidentally, it is a listed carcinogen in some countries as well as California. It is a proven carcinogen in animals.

Toxins commonly cause allergic reactions. A well known example is bee venom. Another is the toxin in poison ivy. Many others exist including snake venoms, jellyfish venoms and various inorganic and organic materials. Even histamine which is the mediator of an allergic reaction in the body is a toxin.

Evan
01-02-2007, 06:30 PM
Evan, you're the one who brought up tumors! :)
Bull.

To quote you with your emphasis:



Human studies are inconclusive regarding inhalation exposure to cobalt and cancer, and the one available oral study did not report a correlation between cobalt in the drinking water and cancer deaths. EPA has not classified cobalt for carcinogenicity.



The poor guy is asking a simple question about what to look for in tungsten wedding rings, and you're trying to get him all worked up about tumors. :rolleyes:

Again, bull. You brought it up, not me.

topct
01-02-2007, 07:04 PM
I like the feel of gold. For this situation gold is best.

Todd Tolhurst
01-02-2007, 07:34 PM
Skin reactions to nickel and cobalt are very common and it most certainly isn't a good idea to buy or make a wedding ring from a material that contains either.

And yet white gold rings containing nickel have been popular for ages. That's because the overwheming majority of people don't have skin reactions to nickel.

Todd Tolhurst
01-02-2007, 07:36 PM
Depending on the type of exposure cobalt can be highly toxic. The occupational exposure limits in air are <50 micrograms per cubic meter.


A measure which implies inhalation of airborne dust, not a lump of solid material on a finger.

Todd Tolhurst
01-02-2007, 07:38 PM
Incidentally, it is a listed carcinogen in some countries as well as California.

And silica dust is a known carcinogen, too. It doesn't make wearing an amethyst ring a health risk.

john hobdeclipe
01-02-2007, 08:00 PM
Tungsten Carbide ring...interesting thought. Be sure to size it right the first time, 'cause the local jeweler won't be much help there, with his little ring sizing machine.

As for the cobalt, remember that in most grades of carbide, the cobalt is only about 3% to 7%. I don't really think it would be a problem unless you're unusually sensitive.

CCWKen
01-02-2007, 08:46 PM
I machined mine out of 303. Held up pretty good, course 2.8 years later I don't need it anymore...

LOL... :) That would be my reasoning. In fact, I'd be looking for a Spearmint gum wrapper. :D

JCD
01-02-2007, 08:53 PM
Tungsten Carbide wedding rings are indeed available on the retail market.
It seems to me that if a persons hand was subjected to enough force to shatter the ring, shattering the ring would be the least of there worries.

Evan
01-02-2007, 09:28 PM
And silica dust is a known carcinogen, too. It doesn't make wearing an amethyst ring a health risk.
Quite so. I already pointed that out (toxin does not equal carcinogen). Silica dust isn't a known skin irritant. Cobalt is.


And yet white gold rings containing nickel have been popular for ages. That's because the overwheming majority of people don't have skin reactions to nickel.
True. Reactions to cobalt are far more common.


A measure which implies inhalation of airborne dust, not a lump of solid material on a finger.
It is still highly toxic in those circumstances. It is that toxicity that also makes it a strong skin irritant. Inhalation toxicity arises from the same powerful irritant property.

Todd Tolhurst
01-03-2007, 12:36 AM
True. Reactions to cobalt are far more common.

If you say so. None of the references I could find on the web would agree. This one is typical:


A total of 2543 cases of occupational ACD were reported during 1991-1997. Cr caused 143 (5.6%) cases of ACD, Ni 176 cases (6.9%) and Co 41 cases (1.6%) of ACD.

I Kanerva L, Jolanki R, Estlander T, Alanko K, Savela A. Am J Contact Dermat 2000 Sep;11(3):155-160.

A.K. Boomer
01-03-2007, 12:54 AM
I know --- Hitnmiss really cut me up with that one too, I read it and then i read his name --- hitnmiss! believe me fella were not laughing at you were laughing WITH you, Your not the only one bro, If they didnt have that fuzzy little thing going on therd be a bounty on thier heads!:p

Evan
01-03-2007, 02:05 AM
If you say so. None of the references I could find on the web would agree. This one is typical:
Your reference doesn't quote rate by exposure. Total cases alone is meaningless. It is likely that far more people are exposed to chromium and nickel than cobalt especially since cobalt is known to cause problems and has strict regulations in place to prevent exposure. The fact that there are cases in spite of the preventative measures argues that it is much worse than the other metals.

Todd Tolhurst
01-03-2007, 03:51 AM
Total cases is perfectly meaningful here. You said cobalt reactions are "far more common" than nickel reactions. What does "more common" mean to you?

ttok
01-03-2007, 09:43 PM
Lazlo -

Close call with your wedding ring knurling! I would take it off in the shop if it were me. Go to the Nimitz Museum in Fredericksburg, Tx and see the signed outline of Admiral Chester A. Nimitz' left hand - it is missing the entire ring finger! He was inspecting some rotating equipment on a ship - had white dress gloves on - snagged and pulled off his entire ring finger! Show your wife that - she will get the message if she objects to your taking it off.

I still have the Vacuoline unopened 5-gal pail. Father-in-law passed away in November and things are just now getting back to "normal". Will call and bring a couple of gallons up in a couple of weeks.

As for rings from fancy materials, I ruined my gold HS ring back in the early 1960's by having a railroad passenger car door shut on my hand! It was the upper half of the dutch door in the vestibule. Did not hurt, but bent the ring so I could not get it off! Had to mash it in the opposite direction - however, it did save my hand in that situation. Would hate to have to resort to carbide tooling to remove a mashed ring! Ha! A.T.

Evan
01-03-2007, 11:47 PM
You said cobalt reactions are "far more common" than nickel reactions. What does "more common" mean to you?

It means how often somebody reacts when exposed.

Citing the total number of cases means nothing if we don't know the number of exposures.

Todd Tolhurst
01-04-2007, 12:05 AM
Sigh.

So, if we did a patch test on a bunch of subjects and counted the number of skin reactions to various metals, then we'd know whether cobalt produces skin reactions more often than nickel, right?

Fortunately, this has been done. You will note that the rate of reaction is quite a lot lower for cobalt than for nickel. There are other studies, and the numbers do vary somewhat from study to study and from population to population, but in all cases I have seen thus far, the rate of cobalt sensitivity has always been less than the rate of nickel sensitivity. If you have citations to the contrary, let's see 'em.


Metal contact dermatitis: Prevalence of sensitization to nickel, cobalt and chromium
Ida Duarte, José Roberto Amorim, Eliene Félix Perázzio, Rutsnei Schmitz Junior
An Bras Dermatol. 2005; 80(2):137-42.

Abstract:
BACKGROUND: Metal contact dermatitis (nickel, cobalt and chromium) is a common dermatosis among several population groups.

OBJECTIVE: To describe the individuals with metal contact dermatitis in the group studied, to determine the prevalence of skin sensitization by nickel, cobalt and chromium, to verify the positive test combinations among these three substances and to compare our results with the literature.

PATIENTS AND METHODS: Patch test was performed in 1208 patients with a presumptive diagnosis of contact dermatitis. Those with positive reactions to metals were selected.

RESULTS: Out of the total sample, 404 (33.5 %) patients had at least one positive reaction to nickel and/or cobalt and/or chromium. There were 487 positive reactions to metals (48% of all positive reactions). Most patients were female (72 %) and white (54%), aged 40-49 years old (25%) and cleaning services workers (59%). Among the 404 patients, 329 (81.5%) had positive reactions to only one metal; in that, 60% were positive to nickel, 13% to chromium and 8.5% to cobalt. Approximately 18.5% had positive reactions to two or three metals and the association of nickel and cobalt was the most frequently observed.

lazlo
01-05-2007, 08:31 PM
Close call with your wedding ring knurling! I would take it off in the shop if it were me.

Yeah, no kidding. I just picked up something that was knurled -- I don't wear my ring around the machine tools. On the oter hand, I'm more concerned with my Wife taking that finger if I gouge my ring again...


As for rings from fancy materials, I ruined my gold HS ring back in the early 1960's by having a railroad passenger car door shut on my hand!

See, if that was a tungsten wedding ring, it would have been fine! :p

Good to hear about the Vacuoline -- I've just about used up my Vactra. I also wouldn't mind meeting some of your model engineering friends next time your up here...

Really sorry about your Father-in-Law A.T....

Robert

Evan
01-05-2007, 10:35 PM
Todd,

That study simply confirms that more people are exposed to nickel and chromium than are exposed to cobalt. Contact dermatitis is an allergic response to a material and requires that the person have been previously exposed to that material to show a positive reaction to the test for that material.



OBJECTIVE: To describe the individuals with metal contact dermatitis in the group studied, to determine the prevalence of skin sensitization by nickel, cobalt and chromium, to verify the positive test combinations among these three substances and to compare our results with the literature.

You will note that the purpose of the study is to determine the exisiting prevalance of sensitization, not the sensitizing potential of each element. Since exposure to cobalt is less common than exposure to nickel or chromium the prevalance of existing sensitization to cobalt will be correspondingly less as well.

Todd Tolhurst
01-06-2007, 07:11 AM
OK, so accepting for the moment the questionable premise that "cobalt reactions are far more common" than nickel reactions actually means "cobalt is a stronger sensitizer than nickel", where is the evidence to support your assertion?

Evan
01-06-2007, 10:27 AM
Several clinical and experimental findings point to cobalt as the only sensitizer and causal agent of hard metal asthma. The clinical features have been clearly defined by bronchial provocation tests, with a prevalence of late phase responses. Epidemiology is still insufficient to configure prevalence and incidence rates for cobalt asthma. IgE and IgG antibodies with cobalt specificity have been demonstrated, but T-lymphocytes and eosinophyls involvement seem to be important in the mechanism of an allergic inflammation in the airways. Such an immunological pathogenesis links cobalt asthma with other manifestation of hard metal disease

http://cat.inist.fr/?aModele=afficheN&cpsidt=4143574
Cobalt sensitivity is almost always accompanied by nickel sensitivity because cobalt is virtually always contaminated with nickel since it is extremely difficult to remove all nickel from cobalt. However, nickel doesn't cause the same lung sensitization that cobalt does. This argues that cobalt is a much more powerful sensitizer than nickel or even chromium with the possible exception of hexavalent chromium.

As nickel is much more common (cement, plaster, stainless steel, coinage, jewelry etc) than cobalt the incidence of nickel sensitivity is much higher.

Todd Tolhurst
01-06-2007, 10:49 AM
Sorry, Evan, but if cobalt is the lone sensitizer for hard metal asthma, that doesn't tell us anything at all about its relative sensitizer strength compared to nickel.

None of the literature that I was able to turn up, in fact, provides any direct comparison between the sensitization power of the two metals. However, the ACGIH threshold limit value for both substances is the same, 0.05 mg/m^3, which doesn't suggest cobalt is a stronger sensitizer.

So, what is your basis for your assertion that cobalt reactions are "far more common" than nickel reactions?

Evan
01-06-2007, 11:13 AM
Sorry, Evan, but if cobalt is the lone sensitizer for hard metal asthma, that doesn't tell us anything at all about its relative sensitizer strength compared to nickel.
It doesn't? People are exposed to nickel fumes constantly while welding with few if any reactions while cobalt can produce a reaction in short order. Since an allergic reaction in the lungs is mediated by the same mechanism as in the skin it tells us a lot about the sensitization potential.

When it comes to allergic reactions I am not talking from "google". I have studied allergies for many years as they are a fact of life or me. Much of what I know has been learned directly from various medical professionals over the years.

IgE (Immunoglobulin type E) is the major mediator of allergic reactions. It is a component of the eosinophils, more commonly known as white blood cells. When they encounter a substance that provokes a response they degranulate and release IgE. This promotes a cytokine cascade that then results in the release of histamine, a potent toxin and vasodilator. This then results in the local destruction of cells as well as a general systemic reaction characteristic of allergies. (this is a simplfied explanation)

If an allergen operates anywhere in the body it also will usually operate in the skin. This is the basis for skin testing for allergies by intradermal injection of suspected allergens.

This argues directly that if a sensitizer operates in the lungs it also operates in the skin with equal efficacy. As nickel does not have the same effect in the lungs it is by definition a lesser sensitizer.

Todd Tolhurst
01-06-2007, 11:46 AM
Clearly, if you had facts to back up your (modified when challenged) assertion ("cobalt reactions are more common than nickel reactions", "no, I mean cobalt is more potent than nickel"), you would have presented them by now.

You do sound authoritative, though, and that's half the battle.

Evan
01-06-2007, 12:40 PM
Clearly, if you had facts to back up your (modified when challenged) assertion ("cobalt reactions are more common than nickel reactions", "no, I mean cobalt is more potent than nickel"), you would have presented them by now.

I didn't modify my assertion.

"cobalt reactions are more common than nickel reactions" was meant to imply "when exposed to either separately".

That is a fact supported by laboratory evidence as shown by the above quoted abstract. It is supported as well by everday experience by welders and people who grind colbalt containing material. Hence, the strict OSHA limits on cobalt exposure.

Todd Tolhurst
01-06-2007, 02:10 PM
I didn't modify my assertion.

If you say so, Evan.



That is a fact supported by laboratory evidence as shown by the above quoted abstract.

No, it's not. The abstract doesn't mention nickel at all, so it's useless as a basis for comparing the sensitization power of Ni and Co. It's also solely concerned with cobalt-induced asthma caused by inhalation of cobalt-bearing airborne dust particles. Tungsten Carbide wedding rings are a very poor source of airborne cobalt dust when used as intended, so it's irrelevant to the safety of the rings on that count as well.

Funny thing: The CDC has this to say about dermal exposure levels for nickel sensitization:


Nickel sensitization typically involves initial prolonged contact with nickel or exposure to a very large nickel dose. [...] There is limited information on nickel levels resulting in sensitization. [...] Among sensitized individuals, a direct relationship between nickel exposure level and severity of the dermatitis has been found. A weak reaction has been reported in individuals exposed to nickel alloys that release nickel ions at a rate of <0.5 μg/cm2/week; a strong reaction was observed for nickel alloys that release >1 μg/cm2/week.
http://www.atsdr.cdc.gov/toxprofiles/tp15-c2.pdf


But this is all they have to say on the topic of dermal exposure levels for cobalt sensitization:

Exposure levels associated with the development of dermatitis have not been identified.
http://www.atsdr.cdc.gov/toxprofiles/tp33-c3.pdf


It would appear that even the CDC doesn't know what level of dermal Co exposure causes sensitization, which obviously renders a comparision with the level for Ni sensitization impossible. Is it possible that you are a more authoritative source of information on this topic than the CDC?

Lew Hartswick
01-06-2007, 02:34 PM
There are millions of people around the world wearing tungsten carbide wedding rings, and they're not developing tumors.."

I'm not weighing in on this "overall" argument BUT: the above is not an
argument to be used in any "logical" discussion.
ie. There are millions of people that have smoked for years and dont have lung
cancer. :-)
...lew...

plastikosmd
01-06-2007, 04:13 PM
we have gone from "highly toxic" to a type IV hypersensitivity reaction...so basically cobalt is as toxic as my cat...."highly toxic" to some, and completely pet-able to others..:) or my cat may be even more toxic due to airborne dander in the house..and his claws..:)

Evan
01-06-2007, 06:01 PM
It would appear that even the CDC doesn't know what level of dermal Co exposure causes sensitization, which obviously renders a comparision with the level for Ni sensitization impossible. Is it possible that you are a more authoritative source of information on this topic than the CDC?

Demonstrating your selective reading skills again?
I said: "Cobalt sensitivity is almost always accompanied by nickel sensitivity because cobalt is virtually always contaminated with nickel since it is extremely difficult to remove all nickel from cobalt."

That also means that it is nearly impossible to quantify the degree of sensitization that exists to cobalt alone in sensitive people. People are rarely exposed to pure cobalt.

Because exposure to either metal appears to increase sensitivity to both, the degree that cobalt alone produces a reaction is unknown. Again, the fact that cobalt does produce a reaction in the lungs and nickel doesn't is clear evidence of the abilty of cobalt to promote a reaction.


No, it's not. The abstract doesn't mention nickel at all, so it's useless as a basis for comparing the sensitization power of Ni and Co.
They don't mention nickel because it has been excluded as a cause. Hard metal disease has as it's major component asthma which is produced by the IgE mediated pathway, the same as nickel reactions in the skin.
-------------------------------------------------------



we have gone from "highly toxic" to a type IV hypersensitivity reaction...so basically cobalt is as toxic as my cat...."highly toxic" to some, and completely pet-able to others.
I already explained that. Allergens are often considered toxins. They cause cell death via a histamine mediated pathway.

Todd Tolhurst
01-06-2007, 06:40 PM
Demonstrating your selective reading skills again?

Well, no. I just don't accept your conclusions.

Fact 1: The dermal sensitization threshold for Co is not known.
Fact 2: The dermal sensitization threshold for Ni is known, at least to a degree.
Fact 3: Inhalation of Co dust is a cause of hard metal asthma.

Fact 1 & 2 render a comparison of the relative sensitization potency of Ni and Co impossible. You'd like to recruit Fact 3 to support your otherwise unsupported assertion that Co is a more potent sensitizer than Ni, but neither you nor I can draw any conclusions about the dermal sensitization power of Co from its respiratory effects. It would appear nobody in the medical or regulatory fields has applied your reasoning, either.

In short, it may be that Co is a more potent sensitizer. Or it may not be. Nobody knows. Not even you.



They don't mention nickel because it has been excluded as a cause. Hard metal disease has as it's major component asthma which is produced by the IgE mediated pathway, the same as nickel reactions in the skin.


So don't inhale cobalt. This does not inform us as to the risks of wearing a tungsten carbide wedding ring, even if they contain cobalt, which is not a given.



I already explained that. Allergens are often considered toxins. They cause cell death via a histamine mediated pathway.

Oh, that's precious. Tutor the physician in medicine, Evan. Maybe he missed the day they taught allergy.

John Stevenson
01-06-2007, 07:17 PM
In short, it may be that Co is a more potent sensitizer. Or it may not be. Nobody knows. Not even you.


Oh, that's precious. Tutor the physician in medicine, Evan. Maybe he missed the day they taught allergy.

No Todd but one thing Evan is an ex-pert at is blowing smoke :D

.

Evan
01-06-2007, 09:42 PM
Stop it John, we're having fun here.



Fact 1 & 2 render a comparison of the relative sensitization potency of Ni and Co impossible. You'd like to recruit Fact 3 to support your otherwise unsupported assertion that Co is a more potent sensitizer than Ni, but neither you nor I can draw any conclusions about the dermal sensitization power of Co from its respiratory effects.
Ah, but we can. They dermal effects are mediated by the same system of the body that produces the lung effects. The IgE activated eosinophils have a particular job to play in the body. They are responsible for attacking parasites in the body such as worms. These eosinophils are especially prevalent in the lungs and digestive system but also exist anywhere that parasites can gain entry, including the skin.

As the abstract I quoted points out, the cobalt reaction is most likely mediated by these eosinophils. This also applies to other ionic metals including nickel. The higher concentration of these cells in the lungs makes the lungs a sensitive indicator of reactivity to a particular sensitizer material, not just in the lungs but anywhere in the body as the reaction is caused by the same sensitivity everywhere. (1)

There is an interesting theory that has some support in studies regarding this sensitivity. In the industrialized countries asthma and related allergic reaction have become much more common in the last 100 years. It seems that when deprived of an "enemy" the IgE producing mast cells become more sensitive, even to materials that would not normally provoke a reaction. When you react to something, say a parasite, chemicals are released that help to dampen the reaction so as to prevent overreacting which may kill the host. (2)

In the absence of any parasites, which is the usual condition in industrialized countries now, these "dampening chemicals" are not present. The system is then more sensitive than usual since the usual human condition is to have at least some parasites onboard. This seems to result in reactions to substances that aren't normally considered allergens. They are usually substances with either toxic potential or unfamiliar proteins.




Oh, that's precious. Tutor the physician in medicine, Evan. Maybe he missed the day they taught allergy.
You assume a lot. Allergies are a specialty and are only lightly touched on in medical school, at least in the past. They would be lucky to have one day to cover it. Hopefully the situation has changed.



Note 1


IgE, mast cells, basophils, and eosinophils constitute essential elements in allergic inflammation. Allergen-specific IgE, synthesized in response to allergens in the environment and in susceptible individuals, becomes fixed to high-affinity receptors on cellular membranes, especially of mast cells and basophils. If these receptor-bound IgE molecules are aggregated on reexposure to specific allergen, these mast cells and basophils produce mediators that result in the allergic response. Principal among the cells drawn to sites of mediator release is the eosinophil.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=pubmed&dopt=Abstract&list_uids=12592295

Note 2


Most of the eopsiophil content of the body is in the subepithelium of respiratory, digestive, and urinary systems. Their granules share some proteins with neutrophils, and also conaitn some unique components. Although not their primary role, Eosinophils can also phagocytose and kill microorganisms. Their main effector function is degranulation and release of their granule content. These granules contain highly toxic proteins that enhance production of oxygen free radicals. Degranulation is induced by IgE/antigen complex binding to the eosinophils. The contents of these granules are especially toxic to parasitic worms, but also damage surrounding tissue. In fact, this same mechanism has been proposed for allergy induced tissue damage, by IgE and eosinophils. Eosinophils are also known to secrete histaminase, an enzyme that breaks down histamine (*link to role of histamine), the main allergy associated secretory product of mast cells. Thus this action of the eosinophil can be viewed as suppression of the inflammatory response and granulocyte migration.
http://sprojects.mmi.mcgill.ca/immunology/cell_non_spec.htm


BTW, in case you are wondering, I know exactly what those notes mean and the meaning of the words used.

On the subject of toxins being allergens is this:
Note also that cutaneous injection also reflected the airway effects which further supports what I have said about how such effects are produced.


During a Florida red tide, brevetoxins produced by the dinoflagellate Karenia brevis become aerosolized and cause airway symptoms in humans, especially in those with pre-existing airway disease (e.g., asthma) . To understand these toxin-induced airway effects, we used sheep with airway hypersensitivity to Ascaris suum antigen as a surrogate for asthmatic patients and studied changes in pulmonary airflow resistance (RL) after inhalation challenge with lysed cultures of K. brevis (crude brevetoxins) . Studies were done without and with clinically available drugs to determine which might prevent/reverse these effects. Crude brevetoxins (20 breaths at 100 pg/mL ; n = 5) increased RL 128 ± 6% (mean ± SE) over baseline. This bronchoconstriction was significantly reduced (% inhibition) after pretreatment with the glucocorticosteroid budesonide (49%) , the β2 adrenergic agent albuterol (71%) , the anticholinergic agent atropine (58%) , and the histamine H1-antagonist diphenhydramine (47%) . The protection afforded by atropine and diphenhydramine suggests that both cholinergic (vagal) and H1-mediated pathways contribute to the bronchoconstriction. The response to cutaneous toxin injection was also histamine mediated. Thus, the airway and skin data support the hypothesis that toxin activates mast cells in vivo. Albuterol given immediately after toxin challenge rapidly reversed the bronchoconstriction. Toxin inhalation increased airway kinins, and the response to inhaled toxin was enhanced after allergen challenge. Both factors could contribute to the increased sensitivity of asthmatic patients to toxin exposure. We conclude that K. brevis aerosols are potent airway constrictors. Clinically available drugs may be used to prevent or provide therapeutic relief for affected individuals.

http://www.ehponline.org/members/2005/7498/7498.html

My emphasis.

Todd Tolhurst
01-06-2007, 10:12 PM
Ah, but we can. [Amateur medical theory deleted...]


Evan, you are as qualified to to theorize on this matter as I am, which is to say, not at all. Even if you were, it's only a hypothesis, and not tested, much less supported, by any experimental trial. As such, your layman's suppositions carry no weight whatsoever.

If you can find a qualified authority to state that Co is a stronger sensitizer than Ni, please let us know. Note: You are not a qualified authority.



You assume a lot. Allergies are a specialty and are only lightly touched on in medical school, at least in the past. They would be lucky to have one day to cover it. Hopefully the situation has changed.


*I* assume a lot!?! You're presuming to teach Discover Magazine-level medical topics to an M.D., but I'm assuming a lot.



BTW, in case you are wondering, I know exactly what those notes mean and the meaning of the words used.


Well, I wasn't wondering, actually; I assumed you understood it. It's not exactly Martian to me, either. However, you did manage to make me feel acutely embarrassed for you. Were you trying to impress me? I'm afraid I don't grasp your purpose in pointing out your understanding.

Evan
01-06-2007, 10:53 PM
If you understood then you wouldn't still be arguing.

Todd Tolhurst
01-06-2007, 10:56 PM
Or, perhaps, if you understood your limitations.

I think we're done with this topic, don't you?

Evan
01-06-2007, 11:01 PM
Agreed.

http://xtx.xhx.zzz.jpg

plastikosmd
01-06-2007, 11:21 PM
grin...I realize I have a lot to learn about nearly everything. no doubt you are a skilled machinist, an intelligent person. i doubt debating how much the immune system and ALL of its functions and dysfunctions are taught, and consequently as to if I can speak to the subject is useless...:)

plastikosmd
01-06-2007, 11:23 PM
err..hmm guess the debate is over..durn didnt wanna be the last hurrah... o well...:)

Tuckerfan
01-07-2007, 03:51 AM
I guess now it's a little late to mention that apparently tungsten carbide rings don't contain cobalt.

John Stevenson
01-07-2007, 05:58 AM
err..hmm guess the debate is over..durn didnt wanna be the last hurrah... o well...:)

Only if Evan is allowed to have the last word.

.

SJorgensen
01-07-2007, 06:41 AM
Who pissed in your Cheerios John?

John Stevenson
01-07-2007, 07:01 AM
Don't eat them Spence.
Do a search and you will find out they are the only cereals that people piss in, you never get anyone pissing in porridge, so why take the chance.:)

PM coming

.

Your Old Dog
01-07-2007, 09:10 AM
So if he don't want to make a grand play with the lady by using cobalt, suggest he do what I did.

My wedding band was ordered one size too small. My bride slid it onto my finger as far as it would go. On the way down the isle I popped it over my finger knuckle and it's has never been off since, not ever. There have been several times when I was told I could not have it on me but I refused to remove it. I plan on taking it off when the marriage is over but it's far from over.

lazlo
01-07-2007, 03:29 PM
Who pissed in your Cheerios John?

Yeah, but John's right. Evan lives for these Google flame wars.


I guess now it's a little late to mention that apparently tungsten carbide rings don't contain cobalt.

I mentioned earlier in the thread -- a quick perusal of the jewlery sites shows roughly half the tungsten wedding rings advertised use cobalt as a binder, and the other half use nickel as a binder. The nickel based tungsten rings are somewhat more expensive.

Evan
01-07-2007, 03:51 PM
Yeah, but John's right. Evan lives for these Google flame wars.

The only reason I used Google was at Todd's insistence. I already know that information quite well as I have studied it long before Google even existed, or the WWW for that matter. I have a considerable library of medical texts that aren't commonly available to the general public, some of which were given to me by doctors and others that I purchased through the local college where I was an instructor. I also know several doctors very well as friends and we discuss medicine on a regular basis.

This is an area of extreme personal interest to me. The two medical conditions that I suffer, FMS and Gluten Enteropathy, are often accompanied by allergies for reasons not well understood.

Todd Tolhurst
01-07-2007, 04:46 PM
I guess we're not done with this topic after all.

Since you're claiming enough expertise as an amateur immunologist to formulate your own theories and pronounce them correct without the bother of experimental confirmation (like real scientists do), a question occurred to me. I wonder if you consider yourself more competent, less competent, or equally competent in immunology as in another field in which you claim considerable expertise, astronomy.

As you will recall, you displayed total ignorance of a basic astronomical vocabulary word ("metal"), and rejected all evidence, no matter how authoritative the source, which disagreed with you.

So I'm just wondering if you are as fallible in immunology as you are in astronomy.

John Stevenson
01-07-2007, 05:00 PM
Love - two................................/:D




.

Evan
01-07-2007, 06:03 PM
As you will recall, you displayed total ignorance of a basic astronomical vocabulary word ("metal"), and rejected all evidence, no matter how authoritative the source, which disagreed with you.
You certainly do have a facination with that particular discussion Todd. I don't suppose you recall any of the information I provided about how that particular use of the term "metal" came about and in particular the way that metallicity is determined solely by iron content.


Since you're claiming enough expertise as an amateur immunologist to formulate your own theories...
I haven't proposed any theory in this area, merely stated facts.

Evan
01-07-2007, 06:12 PM
BTW, Todd,

You also seem to be ignoring a major item that has direct bearing on the original post. You seem to maintain the the evidence points to nickel being a more important sensitizer than cobalt. If that were in fact so then why is it that many of the sites promoting tungsten carbide jewlery go to pains to advertize that their products contain no cobalt, only nickel? Seems that would be a bad thing, unless of course cobalt really is more likely to cause a reaction than nickel.

Todd Tolhurst
01-07-2007, 07:05 PM
You certainly do have a facination with that particular discussion Todd. I don't suppose you recall any of the information I provided about how that particular use of the term "metal" came about and in particular the way that metallicity is determined solely by iron content.


Yes, I recall how you preferred the distraction of talking about "metallicity" instead of correcting your ignorant comment that you had never heard the term "metals" used in astronomy to refer to elements heavier than helium, and that "real astronomers" do not use the term that way. I also recall what a real astronomer told me when I asked him the meaning of the term. Do you recall whether his answer agreed with you, or disagreed with you?

Don't strain your memory, I'll tell you: his answer disagreed with you. You were wrong. Completely, utterly wrong, because you surely had discovered you were wrong during the course of the discussion, refused to admit it, and tried to steer the discussion elsewhere instead.

But, no, I'm not particularly fascinated with that discussion. It just bears a similarity to this one, in which you're asking us to accept data which conflict with authoritative sources based on your personal authority. You've never heard of a term, therefore it does not exist, no matter what the textbooks say. You say PTFE can be dissolved at normal temperatures and pressures, therefore it can, no matter what the chemists say. See the parallel?

Now, here you are again, claiming expertise which exceeds that of authorities in a field. Co is a more potent sensitizer then Ni, no matter what the CDC says. Evan knows better. You really should publish this stuff.


I haven't proposed any theory in this area, merely stated facts.

I do not agree. You are attempting to draw a conclusion concerning the relative dermal sensitization potency of Co and Ni, based on the respiratory effects of Co dust. Your theory, in a nutshell is:

- Inhalation of low-level Co dust causes hard metal asthma
- Inhalation of low-level Ni dust does not cause hard metal asthma
- Therefore, Co is a stronger dermal sensitizer than Ni

Your theory starts off with a silent assumption that the lungs and skin react to a substance in the same way. This is a poor assumption, but let's keep it for the moment and see where it leads. Would it not predict that higher-level respiratory exposure to nickel should cause hard metal asthma? Yet you have said that Ni has been excluded as a cause of hard metal asthma. Therefore, hard metal asthma is a health effect unique to Co exposure, and cannot be used to draw any conclusion about the relative sensitization strengths of Co and Ni.

So, even on the basis of your bad assumption, your theory fails its own prediction. Bad amateur scientist! No cookie!

The only fact needed here is that there is no established dermal sensitization threshold for cobalt. Therefore, no comparision can be made with nickel.


You also seem to be ignoring a major item that has direct bearing on the original post. You seem to maintain the the evidence points to nickel being a more important sensitizer than cobalt.

More potent or more powerful, Evan; not more "important". And I do not maintain that Ni is more potent that Co. I maintain that we do not know. I have, however, posted numbers showing the Ni sensitivity is more common than Co sensitivity, in response to your claim that Co reactions are more common than Ni reactions.



If that were in fact so then why is it that many of the sites promoting tungsten carbide jewlery go to pains to advertize that their products contain no cobalt, only nickel?

Perhaps because even among people who are sensitive to Ni or Co, most aren't sensitive to both. Having a choice of Ni or Co is a good thing. Perhaps because nickel binders make a better-looking ring, as they are less prone to oxidation than cobalt binder rings. Perhaps because product differentiation is fundamental to marketing. I think we can agree that it's certainly not because nickel is hypoallergenic, as some such sites claim!

But we've been over all this before. And you agreed we were done. Wanna try again?

Evan
01-07-2007, 08:27 PM
Your theory, in a nutshell is:

- Inhalation of low-level Co dust causes hard metal asthma
- Inhalation of low-level Ni dust does not cause hard metal asthma
- Therefore, Co is a stronger dermal sensitizer than Ni.

Your theory starts off with a silent assumption that the lungs and skin react to a substance in the same way.


Incorrect. It isn't my theory. It is demonstrated by experiment. And, since the mechanism found to be responsible is common to lung and skin reactions there is no assumption taking place.



This is a poor assumption, but let's keep it for the moment and see where it leads. Would it not predict that higher-level respiratory exposure to nickel should cause hard metal asthma?
It does. I just takes a lot of exposure. Because of that it is uncommon. You can however find individuals that are allergic to almost anything.


Yet you have said {I didn't say it}that Ni has been excluded as a cause of hard metal asthma. Therefore, hard metal asthma is a health effect unique to Co exposure, and cannot be used to draw any conclusion about the relative sensitization strengths of Co and Ni.

It's unique because of the sensitizing potential of cobalt. Nickel is also known to cause asthma but it requires much higher and more prolonged exposure.



So, even on the basis of your bad assumption, your theory fails its own prediction. Bad amateur scientist! No cookie!
I can't eat cookies. Even if I could I don't care for them.

Almost forgot, what about the big deal that is made about cobalt free rings? Why bother? Most people have no idea what cobalt is other than a color.

Todd Tolhurst
01-07-2007, 08:37 PM
Yet you have said {I didn't say it}that Ni has been excluded as a cause of hard metal asthma.

You're denying you said the following in message #51 in this thread?


They don't mention nickel because it has been excluded as a cause. Hard metal disease has as it's major component asthma which is produced by the IgE mediated pathway, the same as nickel reactions in the skin.



Almost forgot, what about the big deal that is made about cobalt free rings? Why bother? Most people have no idea what cobalt is other than a color.

Skipped the second-to-last paragraph of my post, did we? No matter. I'm done with this topic, whether or not you are.

Evan
01-07-2007, 09:26 PM
You're denying you said the following in message #51 in this thread?

Quote:
They don't mention nickel because it has been excluded as a cause. Hard metal disease has as it's major component asthma which is produced by the IgE mediated pathway, the same as nickel reactions in the skin.


Are you familiar with the word "they" and its common usage?


More potent or more powerful, Evan; not more "important". And I do not maintain that Ni is more potent that Co. I maintain that we do not know. I have, however, posted numbers showing the Ni sensitivity is more common than Co sensitivity, in response to your claim that Co reactions are more common than Ni reactions.


I meant to reply to that but forgot.
You also don't seem to read very well. I said my statement that you intially seized upon to start this silliness implied "when exposed (to each metal)".

And, when I said "important" I meant important, not more powerful. As nickel exposure is more common it is by definition more important whether it is more powerful or not.

However, you still haven't explained why the apparent concern by the sellers of tungsten carbide rings about cobalt and their apparent assumption that nickel is a safe(r) sustitute.

Todd Tolhurst
01-07-2007, 09:36 PM
*** Click ***

John Stevenson
01-07-2007, 09:43 PM
Are you familiar with the word "they" and its common usage?

Is that like the Royal "we" ?
:D

.