Thread: Warning! Mother of pearl & shell dust

The true issue is simply that all dusts are irritants, if not outright poisonous, as are some species of wood dusts. The sub-micron crap is the worst as lung cells deal with it differently from bigger chunks. The chronic irritation seem to trigger neoplasms, particularly in those who are genetically predisposed to such things.

I use a lot of shell and slate as inlay in my wood carvings. That means a lot of cutting and shaping with stones and sanding drums running in my drill press (pillar drill?). Easy, enjoyable but dusty.
The front face of the drill spins to my left. The drum spins in the open cutoff end of a 2 liter plastic milk jug on the end of my ShopVac hose. Nothing can outfly my ShopVac, equipped with a plaster dust bag filter.

I have posted an illustrated thread, way down in the Woodcarving forum, hope you can find it, I have long since forgotten the title. Sorry.

Originally Posted by kiwihumidor

Alas woodwork can be an unhealthy pastime. The dust generated by working with shell is very carcinogenic. . . . . .

There's a lot of hype and claims about this one on the web usually perpetrated across craft and associated websites. However, unlike asbestos there does not appear to be a single verifiable death from a cancer that a medical investigation has attributed to exposure to shell dust.

Shell dust can be a strong irritant and may generates very allergic reactions in some people. One theory about why it does this is a small amount of the calcium carbonate (not harmful) in the shell is decomposed into Calcium Oxide (CaO) by heat from cutting tools. CaO, also known as quick lime, is a strong alkaline irritant especially when in a fine dust form it comes into contact with moist membranes like eyes, nose, lungs. If you are worried about this then read the MSDS for CaO [http://www.sciencelab.com/msds.php?msdsId=9927329] - however note that CaO is NOT carcinogenic. Being a soluble metal oxide it has characteristics similar to ZnO which produces "metal fume fever" (most common cause is welding galvanised metal) a not very pleasant and breath taking reaction which feels like a nasty flu. This flu does eventually go away after a few days and does not leave a long lasting effect. Please not that this is only a theory and has not been adequately tested.

If shell was VERY carcinogenic, or even suspected of being carcinogenic, it would appear on the US Dept of Health and Human services Annual Report on Cancer (POC) which is published every year.
This report lists and details the situation with regards ~200 material "which either are known to behuman carcinogens or may reasonably be anticipated to behuman carcinogens".
Note that wood dust has been listed on ROC since 2002.

Because shell is also a widely sold and traded commodity if shell was that "dangerous" it would require a MSDS. I only had a quick look and the only reference to an MSDS for shell that I could find was on an Indian Website but they did not list the MSDS. If anyone can find an MSDS for shell that would be worth positing.

So I agree with RV - treat it like any dust in a workshop - in Australia we should where possible use dust extraction that vents external to a work area.

Originally Posted by BobL

There's a lot of hype and claims about this one on the web usually perpetrated across craft and associated websites. However, unlike asbestos there does not appear to be a single verifiable death from a cancer that a medical investigation has attributed to exposure to shell dust.

Shell dust can be a strong irritant and may generates very allergic reactions in some people. One theory about why it does this is a small amount of the calcium carbonate (not harmful) in the shell is decomposed into Calcium Oxide (CaO) by heat from cutting tools. CaO, also known as quick lime, is a strong alkaline irritant especially when in a fine dust form it comes into contact with moist membranes like eyes, nose, lungs. If you are worried about this then read the MSDS for CaO [http://www.sciencelab.com/msds.php?msdsId=9927329] - however note that CaO is NOT carcinogenic. Being a soluble metal oxide it has characteristics similar to ZnO which produces "metal fume fever" (most common cause is welding galvanised metal) a not very pleasant and breath taking reaction which feels like a nasty flu. This flu does eventually go away after a few days and does not leave a long lasting effect. Please not that this is only a theory and has not been adequately tested.

If shell was VERY carcinogenic, or even suspected of being carcinogenic, it would appear on the US Dept of Health and Human services Annual Report on Cancer (POC) which is published every year.
This report lists and details the situation with regards ~200 material "which either are known to behuman carcinogens or may reasonably be anticipated to behuman carcinogens".
Note that wood dust has been listed on ROC since 2002.

Because shell is also a widely sold and traded commodity if shell was that "dangerous" it would require a MSDS. I only had a quick look and the only reference to an MSDS for shell that I could find was on an Indian Website but they did not list the MSDS. If anyone can find an MSDS for shell that would be worth positing.

So I agree with RV - treat it like any dust in a workshop - in Australia we should where possible use dust extraction that vents external to a work area.

Thanks for the info guys. I got my info from my doctor & an old antique dealer many years ago. I don't use power tools with shell often- usually jewellers saw & files. Most seasoned woodies are aware of the health risks involved with our craft but I often encounter newbies quite unaware of the dangers - my warning was aimed at helping inexperienced woodies.
Your comments have also helped me - as I have good stocks of shell but avoid using them. I may now do more inlays with (a little) less concern.

Cheers,
Kiwi

Working shell for inlay is easy and safe, just be mindful of the dust.
I posted a thread in the Woodcarving Forum that illustrates how I do it.
The chunks 1mm and bigger, I could care less about, not about to snort that.

The sub-micron particles are mineralized. In the lung, phagocytes engulf the particles as phagosomes.
In theory, the added primary lysosomes should be able to hydrolyse the contents. Not so with shell or silica.
More than likely the same for most, if not all, dust particles. That's a guess on my part but I'm not far wrong.
Seems that the serum is 10^-3M Ca++ and the cytoplasm is about 10^-6M. There's a sudden change in plasma membrane permeability, triggered by the failed hydrolysis, and the influx of Ca++ kills the cell. If the serum is held to 10^-6M Ca++, the cells live well. Autolysis was the long-held belief. Just ain't so.

So more phagocytes try to clean up the dead stuff and the process goes on and on. This preoccupation probably undermines resistance to bacteria and fungi. The chronic irritation induces collage development from fibroblasts and that cuts down on lung elasticity and volume.

Take care.