Is Galvanized Steel Poisonous?

A. Hi, Vic. No, it's not "safe" because zinc is not a "food-safe" material. There should be no contact between food and galvanized surfaces. That is because acidic foods can dissolve zinc and we don't want the situation of people eating the dissolved zinc, and the possibility of overdose.

Again, zinc is an essential nutrient not a poison -- but you don't make coffee cups out of aspirin, or rotisserie spits of zinc :-)

Regards,

A. Hi, Joey. As long as the spit (in contact with the food) is not galvanized, it's probably okay -- the enclosure is not a food surface. But paint fumes are not good either. Get it good and hot without food in it a few times first.

I'm assuming you bought this metal, not found it; cadmium looks like zinc but is highly toxic. I read a scary story long ago of a family which used a very old refrigerator shelf as a barbecue grate and got terribly sick -- long ago, refrigerator shelves apparently were, at least sometimes, cadmium plated.

Regards,

A. Hi, Jason. Zinc is not a food-safe material. The temperature doesn't matter, food should not directly be mixed in, nor skewered onto zinc. That doesn't mean it's necessarily a serious hazard, just that guidelines say we shouldn't do it.

Regards,

A. Hi Scott. Nothing is ever totally safe, everything is relative.

But water is still supplied to some homes through galvanized pipe; in the third world people collect their drinking water from rain off their galvanized roof; farmers feed and water their livestock with galvanized troughs; central air conditioning runs through galvanized ducts; furnaces and water heaters use galvanized flues for their exhaust gasses. In short it is very widely used and I personally wouldn't worry about it conveying smoke for a smokehouse.

Luck & Regards,


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

A. Hi, Cliff.

A baby aspirin a day can be good for you or at least harmless, a baby eating a bottle of aspirin can be very bad for it.

Zinc is an essential nutrient, not a poison. The tiny amount, if any at all, of vaporized zinc from your dutch oven is surely harmless, but the clouds of vaporized zinc to which a welder is exposed when welding galvanized metal can be harmful.

Regards,

A. Hi John.

Sorry, but I just don't have any idea what that coating was. It could have been paint. Anything you inhale is bad for you, and can be dangerous because it can coat the air sacs in the lungs. Phosphates and black oxides are usually waxed or oiled, so it may have been vaporized oil. I have heard (not familiar with the actual cases, but have no trouble believing it) that people have died from breathing regular compressed air because the oil dispersed in the air coated their lungs. Your smoker will probably be okay after what is on it burns off, but as I previously said, it's dangerous to use stuff on hand and assume it will be safe because, although odds may be in your favor, we just don't know what it is.

Although I'm certainly no doctor, the danger in smoking cigarettes is proportional to how much and how log you smoke, so I think that a one-time exposure to stuff that didn't seriously injure you rarely has long term consequences. Good luck.

Regards,

A. Hi. Personally I wouldn't give it a second thought if you're not welding it.

Regards,

A. Hi. Zinc is an essential nutrient, not a toxin, but it doesn't sound like any detectable amount could end up in your food anyway.

Regards,

A. Hi, Carol. Don't inhale the fumes, they could possibly give you flu-like "metal fume fever", but you surely don't anyway. I don't know 100% about zinc damaging kiln bricks but I seriously doubt it.

Regards,

A. Hi, Shelley. The feed troughs and watering troughs on many farms are galvanized; people in remote areas have collected rain water off their galvanized roofs for many purposes, including drinking, for decades; and a great deal of water piping (maybe most water piping) was galvanized until a few decades ago. I personally don't think there is any danger whatsoever, but if anyone thinks there is, they are encouraged to post the reason for their concern.

Regards,

A. Hi Tammyleigh,

This is just my opinion. I am not an industrial hygienist, and if I was I wouldn't be able to offer a professional opinion without seeing the described installation anyway.

But if there are particles of anything in the air, a respirator should be worn ... not because of the danger of zinc per se (it's a micronutrient not a toxin) but because particles of anything don't belong in your lungs. As for fumes: if none are visible it's probably not an issue. Again, zinc is not a toxin any more than aspirin is -- they're both for sale at the drugstore; but you can't safely take a whole bottle of aspirin, and you can't safely inhale clouds of zinc oxide. Luck & Regards,


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

A. Hi, Catherine. Galvanized fencing is fine. When we say it's not "food-safe" we mean you should not cook in zinc pots or serve food out of zinc containers because of the possibility of acidic food or drink dissolving the zinc, and you consuming too much of it. Zinc is not poison, it is an essential nutrient; cold prevention tablets are one example of the deliberate consumption of zinc.

Regards,

A. Hi, Catherine. No, it won't.

Regards,

A. Hi, Alex. Although it is bad for welders to breathe zinc fumes, and it may be bad to put acidic foods into contact with zinc because of vaguely possible overdose, zinc is not plutonium, it's an essential nutrient. The MDR for zinc is 15 mg, and it is fairly common to take 100 mg per day to ward off colds and flu. Farm animals eat and drink out of galvanized troughs all the time; and in rural parts of the world people still collect rainwater from galvanized roofs for their drinking water supply.

It will take years for all of the galvanizing to dissolve into the soil, probably decades more for all for much of it to be taken up into the plants; then much of the plant will be thrown away or composted and only a fraction eaten. I doubt that the vegetables have any chance of providing your MDR let alone deterring colds let alone poisoning anyone.

The term "heavy metals" was invented by alarmists, and is a poor one that obfuscates. The term implies commonality between relatively harmless "heavy metals" like tin, iron, and gold on the one hand with extremely hazardous metals like cadmium, lead, and mercury on the other.

Regards,

A. Hi Penelope. Chrome is also an essential micronutrient, and miniscule amounts of hexavalent chrome if even present probably won't survive their trip to either your vegetables or the water table.

Sorry, I never heard this information about frogs avoiding galvanized steel, but I have heard that zinc is poisonous to parrots and even to dogs, so I suppose it's quite possible. Although people are one type of animal, other animals are not people; it is not always true that what is safe/dangerous for various animals is safe/dangerous for us and vice-versa.

Regards,

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 150 years.

Luck & Regards,

A. Hi, Jeff. Most industrial facilities have exhaust systems and fume scrubbers to clean up emissions from processes like these. If you can see & smell fumes, and find them objectionable, in most areas the state EPA will make the shop correct the problem under a nuisance clause even if they do not exceed emission standards.

We still can't even definitively say whether carefully monitored things consumed in definitively measured amounts like coffee, red wine, and milk are good or bad for us -- the answers seem to change every few months. So to try to estimate the possible side effects of an unknown amount of fumes from a process you're not familiar with, that are controlled to an unknown degree, on someone in an office in a different building across the street is simply impossible. Sorry.

Regards,

A. Hi, Ann. I am very sorry to hear of your ill health. It sounds like you believe that your health issues are the result of exposure to something in your work environment and can be accordingly treated, whereas your doctors, who know better than you and I, apparently think your work history has little bearing on the best treatment regimen at this point.

You could try calling a poison control center and see if they have a recommendation for a doctor you can see. A personal injury lawyer may have a specialist doctor they can refer you to who might be familiar with similar symptoms, or might be able to help you in other ways. Best of luck. I'm not making such an assertion, but it is possible of course that your medical issues might have nothing to do with your employment.

Regards,

A. Hi, Chester. Assuming that you never smoked, you may have identified the problem. But if you smoke, please stop; don't be in denial :-)

I smoked but never welded, and I, too, must use an inhaler :-(

Regards,

A. Hi, Linda.

Employers must comply with OSHA standards; it is not optional. Someone can call the OSHA hotline semi-anonymously and have the situation investigated.

However, as much as you may be concerned for your husband's health, it is he -- or better yet his sick co-workers -- who must call, not you. You have nothing to go on but second-hand hearsay about conditions in the plant, and third-hand hearsay about the health of your husband's co-workers. Good luck.

Regards,

A. Hi, Usher.

I haven't personally read of sleep apnea being a symptom of exposure to zinc. Maybe the undertaker will tell your wife different though, since apparently you are not going to go to the doctor even though you stop breathing :-(

Regards,

A. Hi, Dale. As noted in the beginning of this thread and a dozen like it, everything is relative. The amount of zinc exposure from this sounds reasonably minimal, and zinc is considered non-toxic.

What would concern me far more is the possibility of pinhole leaks in your piping which, depending on whether the section under the coals is on the suction side of the fan, could draw carbon monoxide into the house.

Regards,

A. Hi, Richard.

If you have self-converted your vented gas fireplace to ventless, carbon monoxide is a much bigger danger than zinc fumes. Make sure that your gas fireplace is properly equipped with an oxygen sensor. This may be no more exotic than a nozzle in the gas line just before the pilot light, with a carefully designed pair of holes, but it's indispensable (if there's not enough oxygen in the air, the pilot light flame moves further from the end of the gas pipe because it needs more air in order to burn; and so it advances past the thermocouple, turning off the gas.

Regards,

A. Hi, David. Fruit juices are the kind of acidic food that concern us with galvanizing. I don't think your life is in peril, but the taste of your juice probably is. Yes, line it.

Regards,

A. Hi, Anamika and friends. Galvanized metal should not be used for food. Excessive zinc can dissolve into acidic or highly alkaline foods. Plus the galvanized coating might also contain a small amount of lead, and possibly a very thin layer of toxic hexavalent chrome. It's not so much a question of actually dangerous as learning that there are safety codes which govern our design work.

Regards,

A. Hi, Tiffanie.

I don't know whether you really mean "galvanized", i.e., coated with zinc by hot dipping -- but this is certainly not a proper material for ear wires or anything that goes in a piercing. I doubt that polishing it can possibly harm you, but inserting galvanized material into a piercing is not good for the buyer of the jewelry; you should use stainless steel.

Regards,

Hi again.

I suspect that the wire is probably not galvanized, but rather coated or plated with something else, or maybe it's stainless steel. When you buy it, is there any description or specification of what it is? If it is actually galvanized it is not safe for skin contact whether you've had a reaction or not. Use stainless steel wire.

Regards,

A. Hi Dan. Galvanizing often has a final quench in hexavalent chromate. Even though the amount is minuscule, as a matter of principle I would not use metal that has even a minuscule amount of carcinogenic hexavalent chrome on it as jewelry. Probably just as important, galvanized steel won't make for an aesthetically pleasing jewelry item because of its propensity towards white rust and corrosion when exposed to water and sweat. Get stainless steel wire.

Regards,

A. Hi, Arthur.

As far as I know, the thickness of the steel has no effect on the melting point of the zinc coating, which is about 420 °C as mentioned earlier in the thread. Good luck.

Regards,

A. Hi Douglas. We're only approximating that the fence caps are "galvanized", without any detailed understanding of the manufacturing process for those specific parts.

The general rule is that nothing should be used in food preparation that was not intended for use in food preparation because no epidemiologist will have studied the issue and be able to offer any statistical data or facts. So it ends up with people just guessing, and their guesses are always colored by their limited life experiences and their personality :-(

My own personal feeling is that I would run the BBQ for a while with the top open, and then not worry about it. But if someone else would worry about it, I can't say they shouldn't. Sorry, but better answers are not available when we use things for purposes for which they weren't intended.

Regards,

A. Hi Cheryl. With no disrespect, I don't think that's quite the right question. I think the question should be whether galvanized steel is a good finish for jewelry, and I think the answer is "probably not".

Although galvanizing protects the steel from rusting, think about what protects the galvanizing itself from quickly dissolving away in unsightly fashion: a hard, glassy, and corrosion-resistant zinc carbonate skin forms on galvanizing when it is out in the open air and free to react with carbon dioxide. When those conditions don't exist, galvanizing corrodes away with voluminous white corrosion products called "wet storage stain", so I doubt that you will find galvanizing to be a satisfactory jewelry finish.

Regards,

A. Hi Mike. I don't think there is any cause for concern at all, except for the fact that aluminized steel may be more corrosion resistant in this particular application (I don't know).

Regards,

A. To the comments about drinking milk... It's when working with lead, like lead based paints, that when you drink a pint of milk, it stabilizes the lead toxins. I'm not sure if it's the same for galvanized metals.

A. Hi Jens. You'll be happier if you paint a piece of black iron pipe instead. The paint will stick better; you'll worry less (we've explained again & again that it's all is a matter of degree, and nobody can help you decide what the risk is and whether you'll accept it); and galvanized pipe isn't ideal for this wear and type of environment. Good luck.

Regards,

A. Hi Kate. Things are not "safe" vs. "unsafe" -- rather, everything is relative. Far more children die in car accidents than from any other cause, but few parents keep their children out of cars because they are "unsafe".

9 month old children should not be sucking on galvanized objects -- but that does not mean that galvanized buckets for storage is any realistic threat at all to older children. Best of luck.

Regards,

A. Hi Roger. You posted your question under the topic of safety of "zinc" (galvanizing), but you say the heating plate is made of "tin", but it looks like "chrome". Unfortunately, you don't actually know what it's made of, and it's unlikely that any reader would either, unless they happen to be retired from a career working in the plating shop of Broil King :-)

You say this item is vintage, so presumably it's been used many times over the decades. I don't know how a thin shiny plating on the surface of a heating plate could possibly sustain outgassing for decades even if it were made of some exotic poisonous metal, which it's obviously not. Don't worry about it! But if you want something to worry about, consider whether there might be asbestos in the insulation :-)

Good luck.

Regards,

A. Hi Jaime. It was a livestock water container, so it was safe enough for that; and he's barely warming it, so I see no problem.

Regards,

A. Hi Brandon. As mentioned a couple of times, zinc is an essential nutrient not a toxin. The amount of this essential nutrient that you have added to a pool full of swimming water by heating the galvanized pipe is probably not even measurable. Good luck.

Regards,

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A. Hi Elizabeth. Galvanizing might have some small amount of lead in it, it might have a small amount of leachable nickel in it, it might have a very dilute chromate conversion coating on it. I don't think it's particularly hazardous, but the operative idea is that if you re-purpose something, using it for something it wasn't intended for, you have no assurance of its safety for the new application. The designer might not know or remember that people might hang the item on a wall for kids to play with.

If you paint it then it sounds quite safe, but paint doesn't stick well to galvanizing. You'd probably have to start with a primer designed for galvanized surfaces before applying your decorative spray paint. Good luck.

Regards,

A. Have to agree with Ted, even though I sell galvanizing.

It's primarily corrosion protection for steel. It's a zinc coating on the steel that slowly erodes in preference to the steel, until all consumed after which the steel starts to rust (perhaps decades later).

It's not for wearing, eating, etc.

A. Hi Ryan. Please contact your county health department about this. Galvanized pipe was very widely used for water service in the old days but is rarely used today. It may be against local codes. Plastic pipe is probably more common today.

Regards,

A. Hi Ross, I'd suggest getting it red hot outside first because the temperature either will be hot enough to vaporize the zinc or it won't.

Luck & Regards,


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

A. Hi Carlos. If you're not getting that backsplash hot enough that you're worried about burning the house down, I don't think there is any cause for concern. Again, zinc is not a poison, it's an essential micro-nutrient; the problem comes from overdoses that welders encounter when vaporizing the zinc into clouds of zinc-based smoke. But your "stand-off" idea is a good one.

Regards,

A. Hi. Lots of things that get hot are galvanized. Exhaust ducts for furnaces and water heaters, internal parts of gas and charcoal grills, ashpans in airtight stoves, etc. Outdoor burning, which is nowhere near welding temperatures, and where the smoke getting to your lungs and eyes will force you upwind anyway, doesn't sound to me like it poses any issue at all.

Regards,

A. Hi. No problem. And they're probably clear coated after the zinc plating anyway. Of course, China and India are not crawling with lawyers and EPA people like the USA -- so just because it says zinc covered steel doesn't necessarily mean it is.

Regards,

A. Hi Brian. I think people misunderstand the nature of the "zinc fumes" issue. Zinc is an essential micronutrient, not a toxin. It's a problem for welders because of the blinding heat of electric welding vaporizing the zinc, combined with the fact that a welder tends to do a lot of welding, not one little spot weld a month. And I strongly doubt that the zinc coating will even melt, let alone vaporize.

Products very similar to hardware cloth, but woven from stainless steel, are available if you prefer.

Regards,