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Is Galvanized Steel Poisonous?



(-----)
Tutorial:
Galvanizing is a zinc coating applied to steel for corrosion resistance.

Our understanding is that zinc is an essential micronutrient, not a poison or toxin. Farmers spread it on the earth if their soil is deficient in it, people take "cold easing" supplements that are zinc, farm animals have been eating & drinking from galvanized troughs for 150 years, grain is stored in galvanized silos, and some people have collected rainwater from their galvanized roofs for many decades.

Welding of galvanized materials is a well-known danger because the very high temperature of welding vaporizes zinc into a "cloud" of dust which can then be inhaled and cause "zinc fume fever". This illness gives flu-like symptoms for a couple of days. Some feel that this has no long term effects, but our position is that people should not come home sick from work in the first place; galvanized materials should not be welded without proper air-supply welding hoods.

Another less significant danger is consumption of excess amounts of zinc by using zinc as a food surface. Although this would be most likely to happen if storing acidic products in a zinc-coated container, and although it sounds unlikely in most scenarios, it's probably best to consider zinc as not a "food safe" surface.

A final point is that dogs and other animals are not people :-)  Veterinarians have reported serious consequences for dogs from swallowing pennies, and to pet birds chewing on galvanized cages.

Current questions & answers:

December 11, 2021

Hi. I handle crowd control barriers made of galvanized pipe quite a lot every Sunday. My hands get grey stained, is it poisonous? Can zinc and other elements get into the skin easily? Just got this barriers this week, so I haven't used gloves yet. I'm worried that our weekend school children and their parents might sometimes touch the barriers to help out with moving them around. Are we exposing ourselves dangerously if we scratch our eyes or eat something prior to washing our hands? Is it a bad idea to get the galvanized pipe barriers model? I could have ordered the normal steel items but they'll get corroded very quickly. Any advice would be greatly appreciated, thanks a lot.

Kiram Lezzar
Church volunteer - Conroe Texas



December 2021

A. Hi Kiram. I can't say much about the safety of galvanizing and other zinc materials that isn't already said in the "FAQs & TUTORIAL" introduction. Kids have been shinnying up and down galvanized poles for generations without any well-known danger warnings. Considering the multiple serious hazards kids face in parking lots I personally wouldn't worry about it.

7164-3ext

This is not to say there has never ever in this big world been a single report of a problem from handling galvanized materials though; for example -->

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey




September 18, 2021

Q. Lots of concerns about the new galvanized steel raised beds being sold and utilized for garden growing. What are the thoughts of this metal leaching into the soil or foods being grown in these beds?

Katalina Prena
homemaker - Roy, Utah



September 2021

A. Hi Katalina. Why "lots of concerns"? Who is telling you to worry about this, and what are they saying? Please google "zinc in soil" to learn that the amount can vary tremendously without having any effect, but if it's too low farmers deliberately spread zinc on their fields, and it's almost never high enough to stunt plant growth.

As for it's direct effect on people, third-world and off-the-grid people have collected rainwater from zinc-coated roofs for a long time, and farm animals (some of which are far more sensitive to zinc poisoning than humans) have been eating and drinking out of zinc-coated troughs for a very long time as well.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha
finishing.com - Pine Beach, New Jersey





Previous closely related Q&A's, oldest first:

2001

Q. Hello, I work with galvanized steel and I was just wondering if it is poison and if so, what are the harmful effects that it can cause.

Thank-you

Dominic Sumner
- Adrian, Michigan



2001

"All things are poison and nothing (is) without poison; only the dose makes that a thing is no poison." -- Paracelsus (1493-1541)

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A. Hi, Dominic.

Galvanized steel is steel with a zinc coating for corrosion protection. Just as a baby aspirin a day is a healthy regimen for millions, whereas a baby eating a bottle of aspirin is a medical emergency, so too with zinc.

Zinc is most certainly not poisonous! Rather, it is an essential nutrient ["Zinc is an essential mineral that is naturally present in some foods, added to others, and available as a dietary supplement" -- nih.gov]. Cold prevention tablets and nasal sprays are zinc, and it's included in multivitamins.

When you say "work with", is it your job or your hobby? Do you mean you weld it or you just bend and cut it? If you weld galvanized metal, the coating vaporizes, and inhaling clouds of this vaporized zinc can certainly give you "metal fume fever" and possibly worse. Further, there might be very small amounts of lead and hexavalent chromium in/on the articles, and these are poisons.

If you can flesh out your question with a bit more detail about how you "work with" it, we may be able to help! Thanks.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey



2001

A. Dominic,

Is galvanized steel poisonous, you ask. YES, ABSOLUTELY, Don't whatever you do eat it! The harmful effects of its specific gravity on your stomach lining are enormous. It can't be digested. Mind you, you could make up a nice stew by dissolving it in acid but gastronomically this is not Cordon Bleu cooking ... and also poisonous. As long as you don't eat it, or lead, or copper, or aluminum or any metal, you should lead a normal life.

freeman newton portrait
Freeman Newton [dec]
(It is our sad duty to advise that Freeman passed away
April 21, 2012. R.I.P. old friend).




2001

A. How is it you "work with" galvanized steel? If you merely bend it, cut it, shear it, punch it, or roll form it; you shouldn't be in any danger. However, if you are welding it, the welding fumes are dangerous.

The galvanize coating will not be absorbed, by your skin. However, it could have a thin coating of rust preventive oil. Some people have allergic reactions to the oil. You should be wearing gloves. If the gloves get saturated with oil, get new gloves. You could also put protective cream, on your hands. Wash your hands before eating.

If you are not self employed, your company should have a material safety data sheet, for your galvanized materials.

Never eat or drink, from any galvanized product. You could get zinc poisoning. But you shouldn't be doing this, at work or home.

I also believe "lead" has been removed from all galvanize coatings. The EPA forced galvanize producers to remove the small amount of lead which was in the zinc coating.

I have also "worked with" galvanize products for 25 years. It's not something which I believe is dangerous to my health.

Good Luck,

Terry Magyar
steel co. - Columbus, OHIO



2001

Q. Hello.

My brother works with Galvanised steel 6 days a week, welding and bending the steel. I am concerned for his health and was wondering exactly what chemicals are in Galvanised steel and what fumes (names of the fumes?) are being given off? Are the chemicals in these fumes damaging to his health and what precautions can he take? Also if anyone knows of any web sites to MSDS that I could look at that are relevant to the chemicals my brother is being exposed to it would be greatly appreciated.

Thank you.

Heather Davis
- Sydney, NSW, Australia



2001

A. Heather,

A good website for MSDS sheets is siri.org/msds^ (ed. note 10/6/2017: apparently no longer on line). This site provides free MSDS information. There are other sites too if you use any web search engine like google.

Your brother is probably fine. The most hazardous chemicals he would be working with are probably concentrated acids and hexavalent chromium. Both of these are reasonably safe to work with if proper care is taken. He should be able to ask his boss for hazard information. In the U.S., we have the Hazards Communications Act in which providing this information to workers is a legal requirement. I would imagine that Australia might have a similar law.

If I were you, I would be more concerned about the safety procedures at his facility than the specific chemicals. Workplaces need to be concerned about things like railings, good ventilation, first aid kits, eyewashes, safety showers, housekeeping, and chemical handling training. If his management is responsible and concerned about safety, then I would not worry.

tim neveau
Tim Neveau
Rochester Hills, Michigan



2002

A. I looked up zinc poisoning on WebMD and it is poisonous. Heather, you need to let your brother know that inhaling the fumes of galvanized steel will screw you up. I was welding pipes of galvanized steel and I thought I had a major onset of the flu. If he works with it for a living the company he works for is required to let him know all of the risks and preventative measures.

Ian Davidson
- Charlottesville, Virginia



2002

A. Yes, that seems like the metal flu, similar symptoms to the flu, but caused by exposure to the fumes.

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Tom Pullizzi
Falls Township, Pennsylvania



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2002

A. Hello,

I stumbled onto your question while researching the exact topic of welding galvanized surfaces. In my research, I've found that in addition to the numerous common welding fumes that are harmful to inhale, galvanized metals give off zinc oxide when heated. Zinc oxide causes metal fume fever. Good ventilation is the key to welding! Don't breathe all those metals- your body can handle quite a lot, but it's best to minimize your health risks.

Casey Bogen
- Portland, Oregon



2003

A. If you are welding galvanized then you are at a great risk of getting what is called welding fume fever, the symptoms of this are identical to flu but very rarely last longer than 48 hours. If this happens to you once, then think about getting a better extraction system because if this is a common problem then the harm done to you will get worse as time goes on. The body can only take so much before it starts to fail. Also I would recommend that you do some research on the production of Ozone when welding galvanized and other metals such as stainless steel and aluminium.

Gavin Barr
- Sheffield, England




sidebar 2003

Q. WHAT ABOUT THE OLD THING OF DRINKING MILK WHEN WELDING GALVANIZED METALS?

LES DRUMMOND
TRAILERS - DENVER, COLORADO



2003

Q. Les Drummond asked the question about milk. I have also heard that milk will remove the poison. Is it true or is it the by product of too much green smoke?

Randy Brown
- West Milton, Ohio



2005

A. I have been welding on some galvanized panels and old plumbing pipe that I am using to build holding pens and roping arena, I am also a firefighter and have the privilege to be around doctors and paramedics, I was told that if you drink milk it will help offset the poison, although you don't want that to be your primary remedy. I was also told that you can wear a charcoal respirator, I don't know how true this is but I have been sick for the last week, with the wind blowing away from me and all so I don't know.

Michael_L Jordan
self employed welder - Ada, Oklahoma



September 28, 2009

A. I don't know about the milk for galvanizing but it does help after welding stainless steel.

Jeff Keen
- Claremore, Oklahoma



June 10, 2011

A. Galvanise coating is dangerous to your health if ingested (so wash your hands after handling) and if the gas off it is inhaled for example when welding. Inhaling the gas will cause severe flu like symptoms that last about 48 hrs. 'galv flu'. It also attacks the lining on your stomach. Drinking milk before welding lines your stomach and will help but it still goes through your lungs which can't be good! Best wearing appropriate breathing apparatus and in well ventilated area.

Andy Jones
- Old Colwyn, Conwy, North Wales




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2003

Q. I work for a company that welds galvanized steel, and I was wondering where I could find information about the side effects and symptoms associated to the smoke and fumes of the galvanized steel.

Wayne Brown
- Columbus, Mississippi



2003

A. Hi, Wayne. We now have at least six threads about that subject on-line here; so please try the search engine. You didn't say whether you are the safety director for your company or an employee doing the welding. If the former, you have some work in front of you; if the latter, ask your employer for the MSDS and related safety information. Good luck.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey



2004

Q. Hi I have been welding galvanized steel for the last 5 years I wear a air back pack. What sort of affects could I have when I get older. I am 31 years old -- is it harmful?

Jamie Donnelly
sub/contractor - Melbourne, Vic, Australia



July , 2008

A. Hi, Jamie. I think that "metal fume fever" is a good "canary in the coal mine". If you are prudently wearing an air pack and you are suffering no metal fume fever episodes, I would not expect long term problems. However, your employer should somehow offer you access to an industrial hygienist or a doctor. Remember that these public comments are offered by people in the metal finishing industry and users, but generally not industrial hygienists or doctors.

Regards,

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey



2006

i. I just want to add to the ever growing question concerning potential occupational over exposure to galvanized steel. Take note that not only do you need to look for welding fumes, but you also need to look at potential fluorides.

Shawn Jacob
- Lexington, Kentucky



Please clarify that for me, Shawn. Where are these fluorides coming from in the topic of this discussion? Fluorine is an element; it cannot be generated from any chemical reaction; that is, it cannot be released unless it was present in the first place. There is certainly no fluoride in the galvanizing, so please clarify what situation you are alluding to, and what material has fluorine in or on it -- some welding rods maybe? Thanks!

Regards,

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey




sidebar January 5, 2008

Q. Would the same negative affects "metal fumes" result from using a piece of galv. steel pipe in place of a piece of black stove pipe on a wood heating furnace?

I know someone who is using same and have had concerns.

TIA,
David

David_A. Tobey
- Auburn, Washington



January 7, 2008

A. The exhaust ducts on gas-fired water heaters, boilers, and furnaces are almost universally galvanized, and I don't think wood stove ductwork should be much different. I doubt that the outside surface of the duct could ever reach the melting point of zinc, about 420 °C (the hottest point on the outside of my stove reaches about 320 °C); and I don't think even the heart of a wood fire reaches the 907 °C boiling point of zinc.

Still, if you read the installation instructions for wood stoves, most will tell you to use black painted ductwork rather than galvanized. But who knows if any stove manufacturer has ever actually seen a "fume fever" problem, or they are just reinforcing urban legend -- especially since most wood stoves, including mine, have galvanized ash collector trays :-)

Although I personally give little credence to health issues, if the stove manufacturers tell you not to do it, you shouldn't.

Ted Mooney, finishing.com
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey



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