Dioxin vs. Dioxane.

I did not help this with a typo in module 10B. Dioxin is the media name for 2,3,7,8-TCDD. Dioxane is a cyclic ether. Two very different compounds with similar names.

The final word on vinyl chloride - actually two students answered:
1. In response to the statement in module 10B, “The conversion from vinyl chloride to the epoxide (I'm not sure of the proper chemical name, extra credit for someone finding that out for us) takes place in the liver.”  Vinyl chloride is metabolized to chloroethylene oxide, an unstable epoxide.  It is then transformed to chloroacetaldehyde, which is converted to chloroethanol or monochloroacetic acid.  The main toxic metabolites of vinyl chloride are chloroethylene oxide, chloroacetabldehyde, and monochloroacetic acid. There is a lot of information about vinyl chloride, in general, and also its metabolism on the following website:  International Programme on Chemical Safety, World Health Organization, 1996.  <http://www.inchem.org/documents/pims/chemical/pim558.htm>

2.You ask on the hydrocarbon section (http://www.faculty.uaf.edu/ffrap/ENVE_652/Module10/Submodule10B_SolventsHydro/Hydrocarbons.htm) what is the proper chemical name for the epoxide of vinyl chloride.   According to my organic chemistry book, you add oxide to the common name.  However, this would give you vinyl chloride oxide, which isn’t ever used.   So, I’d go with chloroethylene oxide, because this is actually used.  You called it chloroethane oxide, which would’ve been my guess too, but the book says since it started out as an alkene, you keep the –ene.  For the systematic name, you have 2 options:  2-chlorooxirane or 1,2-epoxy-2-chloroethane.   Again, it looks like 2-chlorooxirane is the one that is actually used of the two.
Alkene                                                            Epoxide__________________________________
vinyl chloride (common name)       vinyl chloride oxide (common)
                                                            2-chloroethylene oxide (common and used)
chloroethene (systematic name)     1,2-epoxy-2-chloroethane (systemic)
2-chlorooxirane (systemic and used)

Q. I’ve heard of people in developing counties drinking gasoline to relieve some of the pain when they pull out a bad tooth without professional medical intervention.  You mention that the BTEX compounds are all anesthetics at high doses, and I know gas with relaxed vapor pressure and benzene requirements (like AK and probably developing countries too) are about 30% aromatic by volume.  So, do you think it is  just the BTEX, ethanol, and other light stuff that is getting the job done, or do all hydrocarbons contribute to pain relief.  I am just wondering if they could just as well drink diesel, which is possibly a little less harmful in the long run.
A. Or just pay a colleague to hit them over the head.   As you know, petroleum products are mixtures of chemicals and vary between sources and over time – often quite a bit.  I know that for marine organisms there are vast differences in the toxicity of various crude oils.  The BTEX is generally volatile and therefore absorbed from the air.  The diesel is much less volatile. 

Q. The EPA's Cancer Assessment and Review Committee (CARC) put lindane in the category: “ suggestive evidence of carcinogenicity, but not sufficient to assess human carcinogenic potential”,in other words: a potential human carcinogen. Studies reviewed by CARC showed that lindane was carcinogenic to female mice. Additional studies reviewed by CARC on rats did not show carcinogenicity. CARC believes that certain isomers of lindane may be carcinogenic while others may not.
A. That could be an important point. Often commercial chemicals are not pure at all. If the contaminants don't affect the use of the product, it is not worthwhile to purify the product. However if these contaminants are toxic, their presence is quite important. So, for laboratory testing of the product, a purified version is used, which may give incorrect results.

To answer your question in submodule 10B: The formal name for the epoxide degradation product of vinyl chloride might be “chlorooxirane”. Very good. Actually “2-chlorooxirane”

Q.Classifed as a carcinogen according to the Pesticide Action Network (PAN). [OK site] Data for PAN Bad Actors come from official lists of chemicals with certain toxicity properties. The available lists are generally accurate and up-to-date. However, because many chemicals have not yet been thoroughly evaluated, these lists cannot be considered comprehensive. Source http://www.pesticideinfo.org/Docs/ref_toxicity7.html#BadActor

A. Here's from the homepage of PAN North America:

"Pesticides are hazardous to human health and the environment, undermine local and global food security and threaten agricultural biodiversity.

Yet these pervasive chemicals are aggressively promoted by multinational corporations, government agencies, and other players in this more than $35 billion a year industry."

So they are probably not an unbiased source of information. I often use such sites for information, but don't rely on the them for scientific information, they are “popular literature” a long way from science.

Q. When I search web to get some information about whether carbaryl can cause cancer or not . I found some interesting things. According one paper, I was told at the l ong-term or delayed health effects, this chemical may cause cancer . It is considered a Possible Carcinogen by the World Health Organization, the U.S . Environmental Protection Agency , or another agency. But when I read other papers, I was told carbaryl does not cause cancer . According laboratory tests in rats and mice fed up to 200 ppm (rats) or 400 ppm (mice) for 2 or 1.5 years did not show any evidence of carcinogenicity . (The data are results of animal studies which the Environmental Protection Agency has evaluated in support of the registration of carbaryl. And these data are used to make inferences relative to human health.) It is so weird . Some told me the conclusion - carbaryl can cause cancer . Still others told me another conclusion - carbaryl can not cause cancer . I found each of paper said their data adapting to the standards of EPA . Why theses conclusions are extremely different according the same standards-EPA? I do not know the reason. And I also do not know which one is correct. Dr. Perkins, would do you like tell me which one is correct? the papers' web-addresses are: Carbaryl does not cause cancer. http://infoventures.com/e-hlth/pestcide/carbary.html Carbaryl cause cancer. http://www.checnet.org/healthehouse/chemicals/chemicals-detail.asp?Main_ID=328

A. You must read these carefully. The agencies, EPA, etc., classify substances for regulatory purposes. They use a “weight of evidence” classification. So that is what you found from the agencies, i.e., it is a Group A Carcingen or such. On the other hand, the definition of “carcinogen” is very broad - anything shown to cause cancer, under any circumstances. So, one research can generate cancer in a Fisher 344 rat model and announce – quite correctly – that “XYZ is carcinogenic in Fisher 344 rats” under the dosing conditions the researcher used. The particular dosing regimen used might or might not be relevant for human exposures. Ames and Gold points out that many test procedures might not be relevant for human cancer.