Talk:Hexavalent chromium/Archive 1

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Archive 1

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US EPA MCL For Cr VI

The US EPA does not currently have an MCL for Cr VI, only total Cr. The 0.1 ppm is Cr mentioned in the article is for total Cr. I have edited the article to reflect this. —Preceding unsigned comment added by 199.115.12.254 (talk) 15:41, 20 December 2010 (UTC)

Indiana National Guard v KBG addition

New York Times reported that members of the Oregon National Guard were sent letters advising them of possible exposure from KBG contractors. I added this to the Indiana National Guard v KBG section as this seemed the most relevant location. I added the references to the article. If formatting is incorrect feel free to fix. Also there was no writer attributed to the article other then the Associated Press. Finally, we may need to change the title of the section. I did not want to make too many changes without first posting here. —Preceding unsigned comment added by 161.6.65.56 (talk) 14:59, 12 February 2009 (UTC)

Yes, I fixed the citation formatting. When done correctly it automatically shows in the References Section and should not also be manually placed in the External Links Section. Pzavon (talk) 01:38, 13 February 2009 (UTC)
Americans especially seem to like adding news stories to articles on chemicals. Aside from appearing parochial (it's in my backyard so you better be interested...), these reports raise the question of notability. Wikipedia is probably not the ideal forum for listing incidents, except those of historic significance. Some editors, well intentioned ones, seem to view Wikipedia as a mechanism to alert the populace about pollution incidents. And my guess is that this alerting mechanism is not a sustainable (there are too many incidents) or appropriate for Wikipedia.--Smokefoot (talk) 14:07, 13 February 2009 (UTC)
Your observations make sense to me. What conclusion would you reach? Shout the ING section be removed? Pzavon (talk) 01:36, 14 February 2009 (UTC)

Confusion between the article and the talk page (title added)

The last edit should have been added to the discussion page instead of to the article itself, I suspect. —The preceding unsigned comment was added by Mq@maq.org (talk • contribs) .

I agree —The preceding unsigned comment was added by 212.138.47.14 (talk • contribs) .

Carcinogenicity (title added)

"Some hexavalent chromium compounds are carcinogens."

I thought all hexavalent chromium compounds were carcinogenic. Should this be fixed? --71.227.190.111 03:48, 16 July 2006 (UTC)

Got a source? —Keenan Pepper 04:12, 16 July 2006 (UTC)
Never mind, I found a good one. —Keenan Pepper 04:46, 16 July 2006 (UTC)

It is disputed among experts whether or not ingested chromium VI is toxic. Probably more to the point, how much is necessary to cause injury. The EPA does have the 0.10 mg/L standard, but that does not mean that it is toxic at that level. That is just the level that they know is safe. I'm not sure it matters, but the way the article is written, it states as a fact that chromium causes cancer. In my reading, this is still a debated question. For example, see http://www.ead.anl.gov/pub/doc/chromium.pdf RyanGentry (talk) 01:56, 26 January 2009 (UTC)

The current source being used for the claim that it's carcinogenic in groundwater links to something that only gives the abstract (for free). The abstract doesn't make the distinction of being carcinogenic in groundwater (and proving even that much isn't the goal of the research anyways). Can a better source be found? One that can actually be, um, verified? (I shouldn't have to pay just to see if a wikipedia reference is valid) 209.90.133.67 (talk) 16:59, 19 May 2009 (UTC)
RE: section - Current policies in the United States
Not a big editor here, I rarely remember my login, but I noted the EWG cited here. They're a bunch of scaremongers with little grasp of what's toxic and what isn't - nor do they seem to care. Cr-6 is destroyed by HCl in the gut and rendered back to Cr-3 which isn't anywhere near as nasty. I'm not going to cite my work here as this is fairly well known after multiple scientists ragged on the Erin Brockovich story pointing out that PG&E (while responsible for the cockup) didn't actually have a case to answer re. toxicity or carcinogenicity. Cr-6 IS carcinogenic (and highly so I gather) if INHALED. 81.97.100.208 (talk) 23:29, 3 August 2018 (UTC)
Firstly, Cr-6 doesn't exist. The oxidation state is always referred with roman numbers. Secondly 'Cr-6 is destroyed by HCl' doesn't makes any sense. The water-soluble ions of Cr(VI), namely the chromate-anion and dichromate-anion are indeed rendered to Cr(III)-ions, but the place of this reduction is the leber and not in the gut. Sorry for grammar errors, I don't speak english.

Detection?

Are there any methods to dectect hexavalent chromium in air or water and are they easy to carry out, or do you need your own lab?(Wouse101 22:26, 24 April 2007 (UTC))

All such methods require laboratory analysis. You don't need your own lab because there are commercial labs that will do the analysis for a fee. Sample collection, in air, at least, requires somewhat specialized collection filters that must be shipped promptly to the lab and must be analysed within a few days. Pzavon 01:37, 25 April 2007 (UTC)


The preferred method for occupational air sampling in the US is OSHA ID-215, requiring a sampling pump and PVC chloride filters (5.0 um pore size, 37-millimeter cassette size, 2-piece). Pzavon is right about the time requirements for analysis. [Not logged in] —Preceding unsigned comment added by 75.164.116.78 (talk) 18:26, 5 September 2008 (UTC)

Besides the OSHA method cited above, other suitable methods are also available for the determination of Cr(VI) in workplace air samples. This includes those methods published by the National Institute for Occupational Safety and Health (NIOSH) in the NIOSH Manual of Analytical Methods (www.cdc.gov/niosh/nmam). Beyond the US, other equivalent procedures have been promulgated by, notably, European occupational health institutes (e.g., in the United Kingdom, France & Germany). Voluntary consensus standard methods for Cr(VI) sampling and analysis have been published by ASTM International (www.astm.org) and the International Organization for Standardization (www.iso.org). For a comprehensive review, see K. Ashley, A. M. Howe, M. Demange and O. Nygren, "Sampling and analysis considerations for the determination of hexavalent chromium in workplace air", J. Environ. Monit. 5: 707-716 (2003). —Preceding unsigned comment added by 158.111.5.34 (talk) 20:52, 4 February 2009 (UTC)

External links modified

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Chromium in alloys is not hexavalent (title added)

Per my discussion with stainless steel suppliers who are involved in the European Directive for the reduction of hazardous substances, hexavalent chromium is NOT present in chromium-containing metals. There is chromium in these alloys, but it is NOT hexavaent chromium, therefore d) above is false.

This statement above was removed from the article owing to its style. Can anyone confirm its accuracy - if so, please edit the article to reflect that. Aussie Alchemist 23:25, 16 January 2006 (UTC)

According to Patty (4th Edition) hexavalent chromium particles are generated in the welding of stainless steel. The discussion in Patty mentions several studies of exposure to hexavalent chromium from these activities. It may be that hexavalent chromium is not present in the metal (as aserted by the stainless steel suppliers referenced above), but is produced from chromium of another valence during the welding process. Pzavon 03:26, 1 March 2006 (UTC) The atoms in a metal alloy usually exist in a low oxidation state, normally zero. Metals are normally oxidised on their surface in air. Stainless steel normally has a adherent coating of chromium (III) oxide on its surface, which is why it is stainless. Normal steel has a loose layer of Iron (III) oxides and hydroxides on its surface, which is why it rusts. When stainless steel is welded, it is possible that further oxidation to Chromium (VI) could occur at the high tempertures used. 2corner (talk) 10:04, 22 August 2008 (UTC)

While I won't attempt to comment on the chemical composition of the alloys, hex chrome sampling is almost always performed during welding fume sampling, especially for stainless welding. [Not logged in] —Preceding unsigned comment added by 75.164.116.78 (talk) 18:32, 5 September 2008 (UTC)


The chromium in stainless steel is in a metallic state, not a hexavalent state. The article's introduction should not say that stainless steel includes hexavalent chromium. It is, however, possible for welding processes to generate hexavalent chromium fumes from stainless steels (and many other alloys containing chromium), but that's not unusual: a lot of perfectly safe and innocuous compounds turns toxic when you scorch them. The amount of hex-chrome produced in weld fumes is controllable. References:

http://www.uasinc.com/Documents/General/06ControlHexChromium.pdf

http://www.ncbi.nlm.nih.gov/pubmed/19212602 — Preceding unsigned comment added by 147.160.248.10 (talk) 19:37, 25 August 2011 (UTC)

Hexavalent Chromium MCL

California is proposing 0.06 ug/L. I believe the USEPA is considering 0.1 ug/L at this time but given the current public concern over the chemical this may end up at the California limit.

Gpronger (talk) 23:22, 15 March 2011 (UTC)Greg Pronger

California finalized a public health goal at 0.02 ppm (was previously proposed at 0.06 ppm). This standard is not enforceable but is a step in the process in developing the MCL. — Preceding unsigned comment added by 64.129.227.4 (talk) 23:19, 12 September 2011 (UTC)

Hydroxyl radical formation

Hello, community:

I was browsing through the site and realized there was no citation for the radical-forming role of hexavalent chromium. Perhaps this study is adequate in showing that Cr(VI) can produce *OH. While it is found in this study that Cr(VI) does not produce *OH in a previously suggested mechanism, it is suggested that the hydroxyl radicals are produced in a Fenton-like reaction which is biologically relevant.

What do you all think?

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1567404/pdf/envhper00399-0222.pdf — Preceding unsigned comment added by 173.175.179.126 (talk) 06:19, 25 April 2012 (UTC)

Natural or anthropogenic?

The Greece section of the article says the contamination "is mainly linked to natural processes, but there are anthropogenic cases."

It would be nice if all localities mentioned in the article, including Midland, Chicago, and Milwaukee, had a similar explanation of the cause. 174.24.79.250 (talk) 04:43, 26 May 2012 (UTC)

Conflicting and unclear information on EPA vs. California MCL

From the Toxicity section:

For drinking water, no United States EPA Maximum Contaminant Level (MCL) exists, though the current MCL for total chromium is based on the assumption that all of it is Cr(VI). California has finalized a Public Health Goal of 0.02 parts per billion (ppb or micrograms per liter)[9] and is now in the process of establishing an enforceable MCL.

From the Hinkley, California section:

The 0.58 ppm chromium VI in the groundwater in Hinkley exceeded the Maximum Contaminant Level (MCL) of 0.10 ppm for total chromium currently set by the United States Environmental Protection Agency (EPA).

These statements appear to conflict (the first says EPA has no standard; the second says EPA has a standard of 0.10 ppm). If these statements don't conflict, further context would be helpful as it's unclear. If they do conflict, the incorrect statement should be removed and citations should be added to the correct statement.

Additionally, these topics should be expanded to answer these questions:

  • Why does California have a standard, but the EPA doesn't?
  • What is the scientific basis for California's standard? Has it been sufficiently peer-reviewed?
  • Why hasn't the EPA adopted a standard?
  • What are the points of contention between the EPA and California?
  • What research is currently underway?

73.50.54.57 (talk) 18:18, 20 August 2014 (UTC)

AFAIU EPA has a limit value for total chromium (but not Cr+VI, so no limit for Cr+VI exists).
So this is fine, but there seems to be a mismatch in numbers. From the Hinkley, California section:

The 0.58 ppm chromium VI in the groundwater in Hinkley ... // Average Cr(VI) levels in Hinkley were recorded as 1.19 ppb with a peak of 3.09 ppb.

0.58 ppm would be 580 ppb. Is it a typo? Are 580 ppb in groundwater, but 1.19 ppb in the drinking water people were exposed to? Somebody can clear this up?
2A02:1205:34DA:5F90:CABC:C8FF:FEA7:3DAD (talk) 10:37, 18 September 2014 (UTC)

Article Structure

There is a lot information in the introduction of this article that is not contained anywhere in the body. The only two body sections are toxicity and pollution. There should be sections on the chemical structure, compounds, uses, etc... Dspark76 (talk) 19:55, 11 April 2016 (UTC)

Need a real writer here!

This article as written, is crap!

"A controversial study claimed that from 1996 to 2008, 196 cancers were identified among residents of the census tract that includes Hinkley — a slightly lower number than the 224 cancers that would have been expected given its demographic characteristics.[8][9] 196 cases over 12 years for a population of 1915 equates to roughly 853 cases per 100k population per year. By comparison San Bernadino County averaged 359/100k/yr over the same period.[10]"

Hey, I'm no genius, but 1996 to 2008, wait, let me count with my fingers here, is 14 and not 12 years. Also the comparison is reversed: 853cases per 100K/yr is MORE THAN TWICE the 359 cases/100K pop/yr, so how does this relate to the number of cancers being LOWER than expected, Come'on!

Wikipedia's "writers" continue: "Average Cr(VI) levels in Hinkley were recorded as 1.19 ppb with a peak of 3.09 ppb. The PG&E Topock Compressor Station averaged 7.8ppb and peaked at 31.8ppb.[11] Compare to the California proposed health goal of 0.06 ppb. The same day the study came out, the plume of contaminated water was reported to be spreading.[12] Ongoing cleanup documentation is maintained at California EPA's page. Cr(VI) contaminated water supply is apparently a widespread problem and not isolated to Hinkley.[13]

Again, I am no genius, but I know that "Average...levels" don't mean a thing unless you specify the basis of the average: Were these the average of tests on separate instances at one location? Were they the average of several samples the same day at one location? Were they the average of separate locations? And who cares about the "PG&E Topock Compressor Station"? The reader does not know what that is and there is no context! The ppb levels listed are not provided with a base, typically mass/volume, volume/volume, or mass/mass.

It's not enough to quote something and paste it here. If you don't understand and can write it in plain language, then you're not doing any service! Please provide the link as references at the bottom so at least someone that understand technical writing can benefit from the original reference!

"the plume...was spreading"? The "writer" has not provided any context! What plume? If we're expected to look at the references, then why not just provide a link to the story?

And for the record, it is true that stainless is manufactured without hexavalent chromium, but according to OSHA, it may be generated by oxidation from other forms of chromium during hot work, hence the hazard.

We don't need to know every place in the world where the've found hexavalent chromium. How is that relevant to the theme? Instead the article is lacking in the more central issue of the real debate as to toxicity, permissible levels, political issues, international actions on the substance, legal activity, and comments on the possibility of finding substitutes for the uses of hexavalent chromium. —Preceding unsigned comment added by 146.23.68.40 (talk) 22:45, 12 January 2011 (UTC)

The article mixes measures of ppm, ppt, ppb and micrograms per litre. For consistency any one article should stick with one set of units so that figures are easily comparable by lay persons. Should there be a single standard across WP? — Preceding unsigned comment added by 81.106.15.136 (talk) 09:47, 22 September 2016 (UTC)

Agree with the OP, this article does not meet Wikipedia's standards. For one thing, the lead (intro) section should contain any controversy. It almost seems like intentional censorship via desiccation & boredom. Erin Brockovich, and the movie (not mentioned anywhere) should probably be in the lead as well (as the TOC). This is not a chemical encyclopedia, please don't write like it, that would be poor writing. —In short, please get familiar with Wikipedia standards, we can all have more Fun Getting Smarter.
--2602:306:CFCE:1EE0:64AE:8B1:7AE7:4B77 (talk) 08:48, 17 June 2017 (UTC) Doug Bashford

Toxicity plagiarism

I understand that the people working on this article probably don't have Ph.D.s, but that is no excuse for plagiarism. The section on toxicity has sentences that have been lifted directly from the cited research paper. A sentence must be 70% unique to not constitute plagiarism.

In addition, there is clearly no understanding on the part of the author as to what the research paper is saying, for example: "Insoluble salts of lead and barium chromates were negative in the implantation model of lung carcinogenesis," (which is taken directly from the research paper by Salnikow and Zhitkovich [2008] without enough change--notice I used direct quotes to show I did that and I cited the resource in-text immediately afterward) should not be included in this article. Why? Because the implantation method is when they take hexavalent chromium and DIRECTLY implant it into lung tissue to see if it causes cancer. Since I can think of NO natural situations where chromium would be implanted into a human's lung on a widespread basis and that would be the SOLE source of exposure, why include information that states you can be exposed to hexavalent chromium in many other ways and it has been shown to cause cancer, but if you are implanted with non-soluble salts of it, you should be safe? In addition, to change this sentence so it would be clear, you would need to say something like, "When salts of lead and barium chromates, which do not readily dissolve, were implanted directly into lung tissue, there was no statistically significant indication that the direct exposure caused an increase in cancer cells. However, it should be noted that soluble chromates, which do readily dissolve, were initially shown not to cause cancer when directly implanted but further testing revealed they do cause cancer when they are introduced into the body by more natural means." (These are my own words using the information I gleaned from the same small section of the research paper and rewwrote it so that not only is it not plagiarized (although it would still need and in-line numeric citation), but also the audience that Wikipedia targets would be able to understand it better than the way it is now. 2601:245:C100:F500:D513:2C4:1960:8071 (talk) 09:51, 17 April 2017 (UTC)

The article isn't protected - anyone - including anonymous users such as yourself, may edit it. You've provided a lot of commentary unrelated to the charge of plagiarism. Note that the talk page isn't a platform for personal opinions. You are welcome to edit the article yourself to correct any errors (obviously with supporting cites), and to reword any instances of plagiarism. Anastrophe (talk) 15:34, 17 April 2017 (UTC)
I agree, the OP should man-up & edit the article himself, he seems to have the rare combination of knowledge, energy, enthusiasm, and writing skills to do so. However, I would be tempted to simply delete the offending passages as misleading or irrelevant, —rather than the laborious rewrite he has so skillfully done—Because no matter how skilled, any irrelevancy would just sound like more boring, long-winded crap. (air freshener + crap annoys everybody, pleases nobody) As protection from vested-interest-vandals, I would also back-up my edit with references and perhaps a Talk Section explanation (done). CHEERS!
--2602:306:CFCE:1EE0:64AE:8B1:7AE7:4B77 (talk) 10:14, 17 June 2017 (UTC) Doug Bashford

Lead wrong?

The lead sentence is:

  • Hexavalent chromium (chromium(VI), Cr(VI), chromium 6) is any chemical compound that contains the element chromium in the +6 oxidation state (thus hexavalent).

Huh? I thought hexavalent chromium referred to the element itself in the +6 oxidation state, not (somehow) to all compounds containing it. I.e. "hexavalent chromium" is not some kind of alternate name for the compound "chromium trioxide". How about:

  • Hexavalent chromium (chromium(VI), Cr(VI), chromium 6) is the element chromium in the +6 oxidation state (thus hexavalent). There are several common compounds that are made with it, including chromium (VI?) trioxide, etc.

—[AlanM1(talk)]— 03:41, 23 December 2019 (UTC)

Or maybe, if it cannot exist in that state by itself:

  • Hexavalent chromium (chromium(VI), Cr(VI), chromium 6) refers to the element chromium in a compound in which it has a +6 oxidation state.

—[AlanM1(talk)]— 11:12, 23 December 2019 (UTC)

The term refers to compounds, basically a red flag that these compounds pose a particular danger as a mutagen. Cr6+, an exotic ion, poses no trouble because it exists fleetingly only in some specialized instruments. Hexavalent chromium is jargon. "Valency" is a complicated term that is generally avoided by chemists. Maybe we need to source the terminology.--Smokefoot (talk) 12:42, 26 December 2019 (UTC)
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