Letter 0020

Zinc "whiskers"

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As an Industrial Hygienist I have the opportunity to assess numerous health risks. Never have I seen any research about zinc whiskers or zinc needles. A minor search of professional IH groups has not identified any health based documentation. Of course zinc oxide, zinc stearate, and other zinc forms have been known and assessed for quite some time now. One article I recently read, attempted to draw a comparison between asbestos and zinc whisker exposure. While I can understand the electronic risks, do you know of any health based documentation? I am aware of the court case you directed others towards.

Thanks

Ed Kramer
- St. Louis, Missouri

Would you please give us that asbestos-zinc whisker article's reference please? Sounds a little far out to me.

Tom Pullizzi
Platronica.com
Falls Township, PA

I have not read the asbestos-zinc whisker article, but I do know that a relationship could be drawn between them. In at least one state (Michigan or Minnesota, I forget, but I'm sure there's others), the legal definition of 'asbestos' is any inorganic substance that has a 100:1 length-to-width ratio or greater. By this definition, zinc whiskers are classified as asbestos and a manufacturer could be sued on the grounds that the company is exposing their workers to asbestos. This legal definition is different than the true geologic definition of asbestos, which has this description in addition to others but is limited to a small range of silicate minerals. As a side note, 95% of all asbestos does NOT cause lung cancer. They do, however, cause asbestosis, which is the scarring of lung tissue as these crystals get stuck in the lung, which I'm sure that zinc whiskers could cause.

I cannot remember which state this story came from, but some mining company that mined nothing similar to asbestos was sued for contaminating the river exiting the mining grounds with asbestos. After some scientific research was done, it was found that the mining company was keeping the river TOO clean. Some diatoms (aquatic microorganisms) that grow only in the cleanest of waters produced silica shells with a length-to-width ratio of 100:1 or greater, which met the legal definition. Unfortunately, I never heard about the conclusion of the lawsuit...

Chase Watkins
- Purcell, OK

Yes, certain particle sizes and shapes are troublesome regardless what material they're made of -- think of glass shards and the terrible bodily damage they can do despite how innocuous glass is as a 'chemical'.

Asbestosis is a real disease that had a number of industrial workers as its victims, and who have our deepest sympathy for their tragic fate.

But asbestos became a multi-billion dollar boondoggle, with the American golden goose butchered to feed our gluttonous legal industry. Now that our domestic plating industry is all but gone, it should be very amusing watching our legal industry trying to sustain itself by recovering damages for zinc whiskers from Chinese plating shops :-)

Ted Mooney, P.E.
finishing.com
Brick, New Jersey

+++++

I am a co-author of the article referenced elsewhere on this site. It is not for any individual to make a claim as to hazards of any material. I realize that the comparison to asbestos has raised some eyebrows. First, I would like to say that the article being distributed is an excerpt of a much larger article that was prepared to outline a very specific operational function in an attempt to recover a zinc needle (zinc whisker) contaminated specification environment.
The citing of asbestos properties was made for the purpose of highlighting the fact that it is the shape of the debris, NOT what the chemical makeup, that create inhalation issues.
OSHA's consideration of inhaled zinc. One must do considerable research to discover the documents referenced in the writing of that article. In fact, in a cursory search, the OSHA site has no specific listing for Zinc, but rather Zinc Oxide. For any business concerned with safe and legal operations in America, the issue requires referencing the OSHA classification of whatever the worker may be exposed to in the workplace. There is clear documentation available from OSHA that states inhalation of airborne Zinc particles (Specifically NOT Zinc Fumes nor Zinc Oxide) is considered to be much more than a respiratory irritant.

The following is taken directly from OSHA documentation referencing the hazards of inhaling zinc particles:

NAME: Zinc
IMIS: Z100
CAS: 7440-66-6
DESCRIPTION: Solid.

HEALTH EFFECTS: Irritation-Eye, Nose, Throat, Skin---Marked Respiratory Effects---Acute lung damage/edema Chronic(Cumulative) Toxicity-Suspect Carcinogen or mutagen

I trust this will clear up any questions as to whether statements made in that document are not in line with the OSHA listing.

I am not a metallurgist, nor a doctor. The document in question elsewhere on this site drew attention to the POTENTIAL hazards of inhaling zinc particles in order for our client to determine how his crew should proceed in the operation. Throwing caution to the wind is not prudent in dealing with large scale contaminations of any kind.

VRM

Valan Martini
- Atlanta, Georgia

+++++

"It is not for any individual to make a claim as to hazards of any material."

I could not possibly disagree any more strongly with that, Valan!

It may not be safe to rely on an individual's claims -- but they are the starting point of virtually all progress. Rachel Carson's "Silent Spring" [link is to product info at Amazon] was the seed that started the whole environmental awareness movement. Please don't credit it to bureaucrats! Geez, they were busy carpet bombing our suburbs with toxic insecticides and engaged in city planning that guaranteed extermination of whole species like the Dutch Elm when Carson informed the world just how reckless and shortsighted the bureaucracy was. Carson should have kept her mouth shut!?

Besides, facts are facts irrespective of pronouncements. Are certain compounds actually carcinogenic in the USA but not in the EU, and vice versa, based on the differing pronouncements from the bureaucrats of the varying countries? That is completely ridiculous.

From my own experience, while OSHA was wishy-washying about whether hexavalent chrome was carcinogenic, it was difficult to get chrome plating fumes treated with respect because some architects felt it "was not for an individual to say" that they were hazardous. If someone feels that something is hazardous, they absolutely should say so. And if they feel that, in a world of limited resources and countless ever-present risks, zinc whiskers aren't a significant inhalation hazard for most of us, they should say that too.

Sorry, I can't find mention of your article on this site, Valan, beyond possibly "One article I recently read". If your referenced report is available, please provide a link; and if you can tell us what thread you are referring to on this site, I'd appreciate it. Thanks!

Ted Mooney, P.E.
finishing.com
Brick, New Jersey

P.S.: This "a thing is asbestos if it's longer than it's wide" discussion reminds me of the punch line of an old favorite song, Melanie's "Psychotherapy" [link is to product info at Amazon] :-)

+++++

In silver and copper, the phenomenon has been known for about 425 years now, and for about sixty years in tin, zinc, and cadmium. Check out Scientific American [link is to product info at Amazon], 203:1, 1960, p. 64 -- although the focus is on whisker growth from vapor, basal growth is mentioned. Metal whiskers are discussed in the "Handbook" edition of R. Holm's "Electric Contacts" [link is to product info at Amazon].

Small amounts of lead, antimony, and a few other elements impede basal growth whisker formation -- probably by blocking material transport along grain boundaries.

Interest in metal whiskers is episodic, waxing when another costly failure is attributed to them.

Norman Helmold
- Greenbelt, Maryland

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