Nickel Use in Hot Dip Galvanizing

A. Dr Cook is making some interesting and noteworthy comments. I would particularly like to comment on his statement about nickel refineries and cancers. It has been known for many years that workers in nickel refineries can suffer from excessively high occurrences of cancer; the most common cancers are lung, nasal sinuses and laryngeal. A lot of work has been done on the relative causes in relation to the types of nickel the workers are exposed to and it has been found that one of the most hazardous sources, in broad terms, is water soluble nickel.

However, when considering nickel refineries, water soluble nickel is a secondary interest because the airborne nickel is not in a soluble form. The important issue with refineries is the type of nickel ore being refined. It was established back in the 1920's or 1930's by, I believe, Gawkrodger (don't rely on this name, as I am not absolutely sure of it), in some work done in English and Welsh refineries. He showed that nickel subsulfides are particularly carcinogenic. This work has been replicated on numerous occasion since then and has confirmed these findings. The findings also strongly suggested that suboxides are also a high risk source, but subsequent work has not totally confirmed these findings. However, the bottom line is that when the refineries studied in the early work changed their nickel ore sources to non-subsulfides or suboxides, the incidences of cancer decreased.

One of the major problems with studies involving airborne pollution and cancers is the interference of smoking -- this is well known to cause cancers and can sometimes give false results in studies involving respiratory illnesses and diseases.

A. Trevor,

I am well aware that nickel has caused many cancers in workers in the nickel refining industry. Perhaps 30 or more years ago nickel METAL was listed as a suspected or likely cancer causing agent in humans. In lab animals cancers were often induced using nickel powder. On page 224 of the 2007 Ed. USA NIOSH Pocket Guide to Chemical Hazards (CDC), Nickel is listed as: "TO: Nasal cavities, lungs, skin [lung and nasal cancer]." Thus it is clear that Metallic Nickel need not be soluble to cause cancer. On finishing.com letter number 58320, a steel worker laid her face down on a galvanized steel I-beam and had an allergenic reaction to the galvanizing. I believe that the galvanizer who galvanized that I-beam has 0.05% nickel and 1% lead in his zinc. He did not have a hexchrome quench.

The following methods may reduce Nickel (or Lead) worker exposure in hot dip galvanizing:

(1) Use dust masks (N95; with one rubber band) or personal respirators (two rubber bands and an aluminum nose clip) during periods of visible smoke or dust.

(2) Use a pipe to vent smoke/dust from an ash/skimmings recovery furnace to the outside of the building. This pipe (stack) will corrode though in a year or two due to high temperature and high chloride in the smoke, ash, dust.

(3) Wear a two rubber band personal respirator when transferring ash from the recovery barrel to the transport barrels.

(4) If the kettle has an enclosure, air extraction, and bag house, then be sure they are properly operating.

(5) Some galvanizers advocate rotating the workers (especially the ash/skimmings processing guy) so that one worker avoids excessive exposure. The problem here is that more workers would be exposed.

(6) Good hygiene can reduce worker Nickel (or Lead) exposure. Proper hand washing, not smoking cigarettes which have been soiled by dirty hands, keeping soiled clothing out of the lunch room, can all reduce Nickel (or Lead) exposure for workers.

(7) Grinding or sanding zinc icicles off the product or grinding or sanding before painting the galvanized product needs be properly done (likely with masks), and carefully cleaning up the floor dusts can reduce worker exposure to Nickel (and lead).

(8) If Nickel powder (or lead ingots) is stored, then put it in an isolated non-working area and keep the area around the powder or ingots vacuumed up.

(9) Do timely periodic worker urine/blood testing to determine the actual levels in the workers. Metals of interest include, but are not limited to: Nickel, Lead, Tin, Bismuth, Zinc, and any other metals that may be present.

Regards,

A. Cliff Honicker gave me the name of a woman that worked 1 1/2 years as an office person (1996) in the "nickel plant" during the enrichment of uranium for the U.S. government. She told me that her urine nickel test showed 26 times the maximum allowable nickel in her body. She was also exposed to 14 different kinds of toxic and radioactive materials for which she is receiving compensation from the U.S. government. Thus no conclusions can be made regarding the toxicity of nickel alone, however she thinks the sinus problems that she experiences are due to nickel. Since her exposure was only 16 years ago, the cancer possibility has likely not had time to show up. This entire thread is a "heads up" for galvanizers using nickel in their zinc bath.

Regards, Dr. Thomas H. Cook, Hot Springs, South Dakota, USA