Duke of Pearl - Posted - 09/20/2010:  11:29:34

Well, since I don't really have time to hang much on the Hangout, this thread which generated comments on shell toxicity only just came to my attention: banjohangout.org/archive/156329.

As pointed out in the discussion there are unending references in craft and luthiery literature referring to the supposed "toxicity" of nacreous shell dust, but inevitably these are completely lacking either direct primary evidence or support from published medical studies. In other words, the only "support" for such claims are anecdotal and usually second-hand (stories, gossip, and rumor).

As an excellent example of how these urban myths are passed along, the above thread mentions the famous and now deceased luthier J.W. Gallagher as having suffered from facial skin cancers caused by M.O.P. and abalone shell dusts; but it must be noted that this is a claim being passed along by another luthier, who quotes a comment made by Chet Atkins, who assumedly heard it from Gallagher while visiting his shop.

I'm not familiar with any specific medical details of Gallagher's case, but an almost identical story had circulated for years about the late inlayist Hascal Haile, who claimed that because of prolonged exposure to shell dust he had "suffered deep and disfiguring facial burns, necessitating plastic surgery" (as per an article appearing in the September 1979 issue of Pickin' magazine).

On contacting Mr. Haile he insisted that the information was based on "a whole week's worth of lab work done on [his] case at Vanderbilt University", but after numerous calls I was unable to locate anyone there who agreed with him! A letter sent to me by his physician (F. Tremaine Billings, M.D.) on Nov. 6, 1979, states: "None of us here believe that the dust from the work Mr. Hascal Haile does is causing his problem. We all feel that he picks his skin, pulls hairs, picks scabs off and generally is somewhat manipulative of his skin. Many people use the same material that Mr. Haile does without jeopardy. I would say that if you keep the dust down, have your room well ventilated and perhaps keep a little moisture, so that the dust is not too thick you will do well; particularly after your use of the grinding machinery be sure to wash yourself well and do not pick at your skin."

During my 43 years in doing inlays and commercially processing shell for the industry I've spent countless hours tracking down stories such as this, but not a single one has ever produced hard evidence that shell was the causitive agent in any of the rumored sicknesses or deaths. I've probably inhaled and been exposed to more shell dust than anyone on the planet, and it's always been a major health concern that I not be doing long-term damage to any body parts. In 1977 I was able to get extensive testing done (by one private and one government lab) on all types of shells, including different parts of each shell. The results found NO evidence of poisonous or toxic substances, including: cyanide, bismuth, arsenic, radioactive isotopes, silicone (in its free SiO2 state), lead, mercury or any other heavy metals, in spite of the fact that each of the above (as well as others, such as "apache gas" or glucamite) have been claimed as being released during the working of shell.

This is not to say that shell dust can't be dangerous. But the real danger is more physical than chemical. The dust acts as a strong desiccant (sucking moisture from skin and mucous membranes), and is hard to wash off completely; dust in the lungs can cause lesions to the air sacs (alveoli) and a resulting scar tissue condition known as fibrosis, scars which can also become infected; the dust isn't dissolved by water or body fluids, so can eventually accumulate to dangerous levels. It can also contribute to nose bleeds, corneal scratching, damage to nasal cilia (the tiny hairs which help filter and propel mucous and particles outward and away from the lungs), initiate (rare) protein allergies, and transport infective materials present on raw shells (remnants of rotted organic matter).

But none of these issues involve actual toxins or poisons, and are problems associated with many other chemically inert dusts having sizes in the nanoscale range. As Frank Ford correctly points out, breathing any sort of fine dust is unhealthy. Work outside, use a fan or vacuum, and if it makes you feel better wear a decent dust mask (although not necessary if the above tips are followed -- a mask also interferes with being able to blow dust away from the cut while sawing).

For more detailed information, see "Is Shell Dust Hazardous" in Guitarmaker #16 (June, 1992).

Edited by - Duke of Pearl on 09/20/2010 12:39:47