Talk:Trichloroethylene
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[edit] Solubility
TCE IS soluable in water... (unsigned comment by user:7segment 00:24, 4 July 2006
- Indeed it is. It exists quite readily in dissolved phase in groundwater. Someone should fix ... Nfitz 20:31, 8 September 2006 (UTC)
[edit] anesthetical uses?
"Supplanting chloroform and ether for a significant period of time, trichloroethylene demonstrated superior efficacy..."
This paragraph seems to be talking about uses as an anesthetic, of which I was heretofore unaware. Could someone please make this more clear? --7segment 04:24, 4 July 2006 (UTC)
- OK --done. Mfbabcock (and others) I'm surprised at how few people in the toxicology world are aware of just how many patients received very high levels of TCE with minimal acute problems.
[edit] carcinogenicity
The references to carcinogenicity should stick to well established studies and reviews. Although there certainly are valid concerns for its toxicity and carcinogenicity, these types of data are often difficult to interpret. Mfbabcock 02:28, 8 October 2006 (UTC)
[edit] TCE as an organochlorine compound
The sentence in the health effects section:
"Organochlorine compounds such as trichloroethylene present a potentially serious environmental liability given their great resistance to natural degradation and their high marine toxicity",
does not provide a good characterization of TCE health risks. TCE isn't that kind of organochlorine compound; that description better represents persistant organic pollutants (POPs) such as dioxins/furans, PCBs and chlorinated hydrocarbon insecticides. TCE doesn't pose a significant ecological risk, in comparison with its potential human health risks, and while somewhat recalcitrant, will biodegrade in soil and groundwater. If you're going to have an introductory statement for this section, would be better to focus on the potentially widespread human exposures, the cancer risks and developmental toxicity. Jlowe19 03:09, 21 November 2006 (UTC)
[edit] Some additional comments on health effects section
The metabolism of TCE and its carcinogenicity in animals is a little more complex than discussed in the article. Active metabolites in liver carcinogenicity in mice are trichloroacetic acid (not trichloroethanol), dichloroacetic acid and chloral hydrate, according to the NAS report released in July 2006. So, the following sentence:
"[t]he active metabolite of trichloroethylene is trichloroethanol, identical to that of chloral hydrate. Therefore, concerns of the carcinogenicity of the latter have been raised, and is subject to on-going debate",
should be revised, and moved from the Uses to the Health Effects section.
It's probably an overstatement that "[t]he long-term effects of trichloroethylene on human beings are unknown". The health effects of TCE are better understood that most chemicals, and while there's uncertainty concerning the significance of adverse effects at low levels of exposure, that a different point compared to the one stated in the article.
It's correct that TCE doesn't cause liver cancer in rats, however, TCE has been shown to cause kidney cancer in rats. In addition, the NAS report concluded there was a "concordance" between the animal studies and human experience with regard to kidney cancer, and it appears that kidney cancer is of more concern now than liver cancer. Also, it's a small point, but the IARC Group 2A classification is called "probably carcinogenic to humans". What's there is the NTP ROC designation.
The thinking concerning adverse reproductive effects has undergone some change, and it's now a little more certain that TCE and/or a metabolite is associated with congenital cardiac defects in humans (again from the NAS report).
The statement that EPA concluded TCE is from 2 to 40 times more carcinogenic than previously believed isn't correct - EPA's 2001 report doesn't say anything like that. I've explored the folklore behind that statement in my blog, Impact Analysis (I'll find the links later - it doesn't have a good search engine). It would be better to characterize this sentence as something the popular media has said, or delete it. The best thing to say is that TCE is more of human health concern than previously believed. Jlowe19 14:31, 21 November 2006 (UTC)
--- I agree. Please go ahead and make changes to make the article more factual and less emotional. Mfbabcock 16:31, 21 November 2006 (UTC)
Thanks. The revisions to the health effects section will be posted shortly.
Jlowe19 16:45, 22 November 2006 (UTC)
[edit] Revisions to health effects section: 11/25/06
Updated the introduction to focus on the principal reason for concern about TCE - the widespread nature of exposure.
Revised discussion of carcinogenicity to reflect the current assessment as presented in the NAS report. Included a contrasting review regarding kidney cancer (recently published in J. Urology).
Revised discussion of developmental toxicity to reflect current assessment as presented in the NAS report.
Presented a more detailed chronology of the review process for TCE, from the "state of the science" review, through EPA's 2001 reassessment and the NAS report. Removed the misleading conclusion that EPA found TCE to be from "2 to 40 times more carcinogenic". It's a factoid as I've discussed here: http://impact_analysis.blogspot.com/2006/04/more-of-tce-story-missed-by-la-times.html.
Provided more description of the extent of TCE contamination in groundwater, noting there are more than just sites in the DOD and DOE complexes.
Removed misleading statement regarding chloral hydrate metabolite from the "Uses" section.
Jlowe19 10:31, 25 November 2006 (UTC)
[edit] Health Effects section references added
References have been added for the revised information in the health effects section. Jlowe19 20:24, 2 December 2006 (UTC)
[edit] Salina contamination
I have added a link to the Salina, Kansas page under the contaminated cities section. Although, strictly speaking, the TCE leak from KSLN hasn't quite reached the water supply yet... How should we handle this? Some kind of note? —Preceding unsigned comment added by 198.67.36.168 (talk) 14:23, 16 May 2008 (UTC)
