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How toxic is chrome plating

Q. Hi everyone. I have a chrome-plated drain cover on my laundry floor. My elderly cat has become senile and keeps missing the litter tray so the urine goes down the drain. The whole drain cover now has dark blue "corrosion" from the urine. Is this a hexavalent chromium salt or is this a salt of the underlying metal? I am very worried about toxicity issues (for both myself and the cat!) in relation to contact with hexavalent chromium. Thank you.

G Evans
Householder - Melbourne Victoria
May 15, 2022

A. Hi G. There is no hexavalent chrome in/on chrome plated articles, and even dissolving chrome plating in strong muriatic acid won't produce hexavalent chromium.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
May 2022

⇩ Related postings, oldest first ⇩

Q. Hi. I have read that chrome baths involve using chromium VI and other toxic substances. I am wondering, is a chrome-covered object dangerous if the chrome is starting to flake off? In other words, is the chrome finish itself toxic if its inhaled or ingested?

And if chrome finish isn't toxic, then how can it get from being dangerous during the application process to becoming harmless? Thanks

Chris Yu
student - College Park, Maryland
March 20, 2008

A. Simple--Chrome metal has a valence of 0 while chrome in a conventional chrome plating solution has a valence of +6.

Major difference!

James Watts
- Navarre, Florida
March 21, 2008

Q. Thanks.
I also read that HCl can oxidize chrome metal with a valence of zero into trivalent chrome. Hypothetically, if a person vomits onto a chrome plated object, does that chrome become oxidized into trivalent chrome?

Also, I read that decorative chrome plating found on most household objects are nickel-chrome plated. When some of the chrome is chipping off, does that expose the nickel underneath? Will that nickel react with carbon monoxide (i.e., from a gas stove) to form nickel carbonyl?

Chris Yu [returning]
student - College Park, Maryland
March 25, 2008

A. I don't know whether enough stomach acid is released to actually dissolve any of the chrome, Chris, and it's hard to imagine a more distasteful experiment :-)

But trivalent chrome is a "health food" supplement, so there is certainly little danger from it. Similarly, nickel is widely used without any chrome overplate, and poses little hazard except that some people acquire nickel-induced contact dermatitis (nickel itch).

I don't know the exact process for manufacturing nickel carbonyl, but I understand that it is usually done at elevated temperature and pressure, that catalysts speed the process, and that fine nickel powders are used in order to present a very large surface area. I would imagine that the rate of production from exposing a nickel plated object to the reducing region of a gas flame would be negligible.

The conversation will probably attract more of the potential responders who you are trying to engage if you state your thesis, or give the context of where you are going, rather than spoon feeding us a string of abstract hypothetical questions :-)

Thanks. Good luck!

Ted Mooney,
Ted Mooney, P.E.
Striving to live Aloha - Pine Beach, New Jersey
March 25, 2008

Q. Yesterday I ordered "chrome" dumbbells from Amazon. At the time I was thinking they were less toxic (to the environment during manufacturing and to me as the end user) than the variety of covered bells out there for sale. Without further information, would you agree? Is there any reason to believe without chipping that it it ingested through the skin like the junk jewelry metals (cadmium for instance)? Thank you for any insight. Sue

Susan Corrigan
- Washington, DC, USA
January 10, 2018


A. Hi Susan. Unfortunately, it's not possible for people to do much but guess :-(

When something is advertised as "chrome" these days, it actually means nothing except that it is bright and the general color of chrome plating. It might be "chrome-look paint", or zinc plating with a clearcoat paint over it, or actual nickel-chrome plating.

But assuming that it is real nickel-chrome plating, it poses no acute danger ... although some people are allergic to nickel or acquire allergy to it ("nickel itch)". Since the USA has no prohibition yet against nickel even in rings worn 24/7 or in pierced jewelry, I don't think nickel-chrome dumbbells will realistically be a problem, and barbell handles were/are nickel-chrome plating for decades -- but you could wrap the handle with duct tape or clear packaging tape if you wish. Enjoy.


pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
January 2018

Q. Dear everyone, I have a related question.

I was once told that hexavalent chromium is only contained in the layer of conventional chromate conversion coating. There should be none for regular use.

However, my water faucet pipe is made of brass with nickel plating. I have recently noticed it is flaking off on the inside where the chrome plating touches the water, and I have no idea how long it has been going on. I have been drinking water from the pipe for years.

Here is the question: Does anyone happen to know if I could possibly ingested chrome metal in form of valence +6?

Chemistry is not my area, if you happen to know the answer would you try to explain it as if you were talking to a child? I really want to understand it, and thank you so much !!!

Farah Thomas
- Austin Texas
July 31, 2021

A. Hi Farah. As an aside, table salt is sodium chloride, NaCl, a compound/chemical combination (not merely a mixture) of two elements. Both sodium and chlorine are highly poisonous, but when in the ionized form that each is in when chemically locked together as in table salt, they are harmless. Importantly, there is no practical way, for the sodium ions in salt to morph into sodium atoms at a different, dangerous, ionization/valence state, and the same goes for the chlorine.

Chromium is an element as well, but there are industrial techniques which are capable of converting it to different ionization states:
0 - metal, what you see on your faucet.
+3 - trivalent, what you see as a health-food store supplement.
+6 - hexavalent, the chemical used in a chrome plating tank and was used in Erin Brockovich days in some industrial water treatment processes.

There is no way for your body to convert metallic chrome or trivalent chromium to hexavalent chromium. But if your faucet were actually flaking into shards of metal, they could be bad for you in the same way that shards of glass are bad for you; that sounds very unlikely though.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
August 2021

thumbs up sign Dear Ted,

Thank you so much for being so kind and explained it so clearly to me. You are saying that the chrome plating flakes I consumed can't be hexavalent chromium. Did I understand correctly?

Have a nice day!

Farah Thomas [returning]
- Austin Texas
August 2, 2021

A. Hi again. You understood correctly.

Luck & Regards,

pic of Ted Mooney
Ted Mooney, P.E. RET
Striving to live Aloha - Pine Beach, New Jersey
August 2021

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