Manganese

[MatthewV]

The Lancet recently classified manganese as neurotoxic. To avoid another internet ranting place about Fluoride, which was also classified as neurotoxic, I have used the harder-to-read journal source.

http://www.thelancet.com/journals/laneur/article/PIIS1474-4422%2813%2970278-3/fulltext#article_upsell

 

Maybe it is time to phase out glazes that use this metal.

 

Summary from the Lancet:

Neurodevelopmental disabilities, including autism, attention-deficit hyperactivity disorder, dyslexia, and other cognitive impairments, affect millions of children worldwide, and some diagnoses seem to be increasing in frequency. Industrial chemicals that injure the developing brain are among the known causes for this rise in prevalence. In 2006, we did a systematic review and identified five industrial chemicals as developmental neurotoxicants: lead, methylmercury, polychlorinated biphenyls, arsenic, and toluene. Since 2006, epidemiological studies have documented six additional developmental neurotoxicants—manganese, fluoride, chlorpyrifos, dichlorodiphenyltrichloroethane, tetrachloroethylene, and the polybrominated diphenyl ethers. We postulate that even more neurotoxicants remain undiscovered. To control the pandemic of developmental neurotoxicity, we propose a global prevention strategy. Untested chemicals should not be presumed to be safe to brain development, and chemicals in existing use and all new chemicals must therefore be tested for developmental neurotoxicity. To coordinate these efforts and to accelerate translation of science into prevention, we propose the urgent formation of a new international clearinghouse.

[Guest JBaymore]

The potentially toxic properties of manganese compounds in ceramics usage have been known for a LONG time.  The largest hazard is to the potter and it is from fumes (tiny, tiny dust particles) from the kiln gases as the manganese vaporizes during firing.  Of particular concern to the potter is the saturated (gorgeous!) glazes that give such wonderful micro-crystalline surfaces.... because of the very high concentrations of the manganese compounds in them. 

 

The biggest issues are upon inhalation.

 

Out of caution (lacking actual leaching studies), it has been good practice to avoid this colorant in glazes used for functional wares for a long time also.

 

It is important to temper this toxicity information with the occupational health concepts of intensity, duration, and frequency.  Also the form of the chemistry...... oxides, salts, carbonates, and so on... and their bioavailability.  This is not a simple subject.

 

best,

 

...............john

[Marcia Selsor]

Bill Alexander and Monona Rossol were both early writers about such hazards. Bill was in Bozeman Montana, Head of the School of Art in 1977 and Monona wrote for ACTS.monona presented at NCECA/Supermud in1978 at Penn State.

I think Bill had an article in an early Studio Potter magazine on health hazards such as manganese and chrome.

Marcia

[MatthewV]

Hopefully everyone is aware of the dangers of working with raw materials. This analysis puts manganese in the same league as lead and arsenic. Because manganese is not exactly an everyday material, I suspect hearing more about this is unlikely.

[rayaldridge]

I've always wondered about those dark clays that contain manganese as a colorant.  I would never use such a clay, and none of my glazes contain manganese.  This may be an overabundance of caution, but I don't think manganese glazes are so wonderful that I can't do without.

 

All that said, I doubt that small amounts of manganese in a good non-leaching glaze are a grievous risk.

[Roberta12]

One of the clays I use is Speckled Buff from Laguna Clay.  I thought it was manganese that made the speckles.  But it is not listed on the msds sheet.  However, I just picked up a box of Continental clay to try and it says mid range oxidation with manganese.  If I understand this, the concern would not be using it to throw, but when it is being fired?  Is this correct?

 

r.

[Guest JBaymore]

Roberta,

 

When "granular" manganese dioxide is added to a clay body to create "speckles", it is likely that the material contains the "fines" as well at the larger particles.  So this contributes to the manganese that is in the general body in a "dust" form (as opposed to the true granular... "large" lumps).  A very dark body with a manganese bearing clay or the addition of manganese dioxide also likely has "fines".  So this situation contributes to the potential issues that the general studio dust creates... beyond the 'standard' carcinogen issue with respirable free silica and also the silicosis risk that comes with any clay body.

 

How exactly this all plays out is very complicated. Occupational health studies available on chronic manganese toxicity have not been targeted at potters and how they use the material and how they typically work (to my knowledge).  So the best we have to go on is trying to make sense of 'what is out there'....and "guestimate" how it might apply to us.  A lot of the info we can get is from industry... and it is sort of not a good model for what we do. 

 

Additionally a lot of the stuff you hear circulating in the ceramic community is either apocryphal or second hand.  ( ie - "My friend told me that Ralph got lung cancer from breathing clay dust in his studio" .... when what you don't know is that, yes Ralph got lung cancer all right, but Ralph also smoked 2 packs of cigarettes a day for the past 30 years.) 

 

And in another vein, in some cases, it is based on assumptions about cause and effect relationships that are not there (or are not statistically proven).  Bad science.  ("ie- Bob worked with manganese in the studio... Bob got Parkinson's Disease......... working in the studio with manganese will cause Parkinson' Disease.)

 

There is sufficient evidence that manganese fume (MnO₂) is an issue upon inhalation.  That comes, in our case, from firing in kilns.  Extrapolation says that if the dust from dry clay bodies is of respirable size, then it might very well present the same issues.  But that extrapolation might be wrong too.  There is some evidence that it is also toxic upon chronic ingestion (in larger amounts).  Skin contact thru intact skin appears to not be an issue (mucous membranes and cuts and abrasions aside).

 

As I mentioned above... you also have to look at intensity (what is the actual exposure level), duration (how long do those exposures last), and frequency (is the exposure infrequent, frequent, 24/7, or what).  That kind of stuff is a 'standard criteria' that must be looked at in determining occupational exposures.  In most studio artists cases... we do not have real data on intensity, we often do not know the real duration.... and the frequency is also often not really determined (example-is your studio in your living space?????).

 

So lacking hard data (air sampling and the like), the prudent thing most people do is to assume that the exposure is quite significant.... and "play it safe".  Might this be "overkill?  Of course.  Some might call it "hysteria".  Having done some air sampling in my history of doing and teaching this stuff, the exposures likely are less than what everyone assumes they probably are.  But individual circumstances vary SO much that it is hard (and not prudent) to assume that kind of thing.

 

So maybe it comes down to the "glass half full / glass half empty" stuff.  If something has not yet been proven to be an issue (in the form and way you use it) is it safe?   How one answers that likely determines how one approaches hazards in the workplace.

 

best,

 

................john

[Roberta12]

Thanks John, for always giving a thoughtful, educated reply.  I appreciate it.  The more time I spend in the ceramics community, the more I realize just how much I do not know.   

 

Roberta

[What?]

I am the hobbyist potter.Good thing is I get X-rays and MRI's of my lungs every couple years just to keep an eye out for anything. Over the course of my manufacturing career I have worked in and around some Stuff. Looking at the SDS's you would think you would get cancer suffer some neurological disorder and have complete shut down of your liver and kidneys in a year. Not the case. I was actually surprised when incidents would occur and we would have to dress to level A or B and then monitor releases with the Dragers. It was not as bad as I would have thought it to be. So glad we have those suits and SCBA's though.  Always better to err on the side of caution, but get your testing and data in order to come to a sensible conclusion.

 

Gasoline now that's a good one!

[Guest JBaymore]

  The more time I spend in the ceramics community, the more I realize just how much I do not know.   

 

Thank you.

 

Me too.  One of the beautiful things about ceramics is that you will never get bored... because there is always more and more to learn.  I've got 100 lifetimes planned out.

 

best,

 

..............john

[bciskepottery]

Most of the safety/handling/toxicity information/regulations/practices that are out are written for industrial and other environments where OSHA and other groups are focused on worker safety and environmental concerns. My understanding is few, if any, studies have been done at the individual pottery level -- and, while industrial practices and rules are often good guidance and informative, they are very hard to apply to our situations -- folks like us who work in a studio set up at home or who have standalone studios. Doing air exposures tests just aren't practical for our pottery work places.

 

In general, whether its manganese or any of a number of similar materials, practicing and using standard dust control methods have you covered -- a properly fitting respirator (P-100) when working with dry ingredients, cleaning up wet, cleaning often, having a good air exchange/filtration system in place and not letting dust/remnants accumulate in your studio. There is no risk to you while throwing (or it would not have that nifty non-toxic label on the box). If you're really worried, throw in gloves. Use common sense and common sense practices and you should be okay.

 

Learn about the materials you use and that are in the products you buy. Any clay manual worth its binding glue will tell you which materials are toxic and hazardous. Use Google (and information from trusted websites). A simple search will tell you that the manganese mining industry has been studied at length and limits have been set for the maximum amount of allowable airborne particulate manganese. The levels that cause miners to be at risk are the same as those that would cause you, a potter, to be at risk for manganese toxicity. Just remember, they are at risk in much higher concentrations and levels of exposure that we are. It will take an average potter (like those who are the majority of forum readers/practitioners)to reach comparable levels of exposure as those in industry. In the same way, manganese fuming has been studied extensively and you can read all about it. Manganese exposure and manganism have been studied since the 19th century. Safe dietary levels of manganese have been studied and there are a number of studies that account for manganese leaching along with other heavy metals like cadmium and lead. There are studies that show a link between manganism to Parkinsons-like symptoms and other neurological disease. If you have any history of neurological concerns or illness, check them out with your physician or knowledgeable health care provider.

 

Then, take what you learn and put it in context -- or as was pointed out in another post -- "temper this toxicity information with the occupational health concepts of intensity, duration, and frequency." I doubt there is enough manganese in the clay that will fume during a kiln firing that will drop you on the spot. Work with it in high concentrations every day, be exposed to its fumes in a factory every day, use high concentrations in glaze and stick your arms in it all day long -- yep, you are likely to show symptoms. But I doubt that is your everyday experience with manganese. Common sense tells us that breathing kiln fumes of any sort is not advisable, why start with manganese?

 

What it comes down to is "how you feel." Inform your feelings, don't let them be overly influence by fear. There's a lot of data on manganism and exposure out there and, as suggested, it's all about how you approach -- and mitigate -- any risk.

 

BTW, I use two clay bodies that contain manganese -- one a cone 6 similar to the one in question, another a cone 10. I also use manganese in a slip I use for salt firing.

[Babs]

I read of a potter in Western Australia who developed a neurological condition but she was also laundering her partner's mining clothes, shaking them out before washing..... straw that broke the camel's back. AND of an era when masks, were not used and sanding back manganese coated clay was "OK"

[Marcia Selsor]

John,

I agree with most of what you have said but I believe both David Shaner and Hans Coper suffered from the effects of using a lot of manganese in their clays and glazes. They had the symptoms of deteriorated nervous systems and muscular disorders. David was convinced if was from the fumes when he fired.

Marcia

[Guest JBaymore]

I read of a potter in Western Australia who developed a neurological condition but she was also laundering her partner's mining clothes, shaking them out before washing..... straw that broke the camel's back. AND of an era when masks, were not used and sanding back manganese coated clay was "OK"

 

This concept is called "total body burden".  It deals with the exposure you might get of a particular toxin form multiple different sources.  So let's say you are a potter and are exposed to silica dust in the studio.  And your hobby is off-road driving in the US southwest.  The exposure to silica dust from you pottery activities is not an issue .... low-ish levels.  BUT that silica laden dust you are breathing from the open cab off-road Jeep ...when added to the exposure in the studio... and bingo... problems.

 

Years ago (like 20 or more) ......... when I was  teaching a section on toxicology I had a student (older, non-traditional) come up to me after a class where I was discussing manganese and the typical symptoms of manganism.  He said to me, "I think you just diagnosed the issue I have been having that the doctors can't track down."   

 

Making a long story short... first of all he was going to the wrong KIND of doctors.  He was seeing GP type folks up until then.  No one was yet looking for any possible environmental toxins.  I recommended he see an occupational health specialist at the Occupational Disease Clinic at Peter-Brent Brigham Hospital in Boston.  So it turned out that he was a full time ceramist and a part time photographer.  He was working with saturated manganese glazes for those lovely iridescent matte, micro-crystalline glazes.  Electric kiln... no local vents (in those days).  He was also working with wet process photos stuff that used manganese.... and in those days...... without any protective gear like gloves.  VERY unfortunately for that he was using a salt of manganese... (chloride)... which is absorbable in skin contact. 

 

Unfortunately, Total Body Burden got him.   Confirmed manganism.  I ran into him one time many years later...... by then, even though he had stopped working with it, basically his condition was indistinguishable from Parkinsons.  Very sad.  He has since passed away. 

 

The only obvious sources of manganese for him were the ceramics and the photo stuff.  In talking to him.... he said it was "confirmed"... but I do not know the precise details of the testing regimen used by the Doctors to confirm the diagnosis... so in that sense this is "second hand" information. I do not have copies of, nor did I ever see, the medical records.

 

best,

 

..................john