Re: non-combustion oriented volatilization

[cmcr@ism.net (Cold Mountain, Cold Rivers)]

i'm learning a good deal from this discussion, but i have a recurring set
of questions.  dr. shadoff wrote:

>Date: Sun, 4 Aug 1996 16:02:12 -0500
>From: lshadoff@brazosport.cc.tx.us (Lewis A. Shadoff)
>To: dioxin-l@essential.org
>Subject: Re: non-combustion oriented volatilization

>UV light causes free-radical reactions to occur.  Initial attack is at the
>carbon-chlorine bond.  If hydroxyl is present, for instance water, it
>attaches forming the aryl-hydroxy compounds.  Once a chlorine in the 2,3,7,
>or 8 position is substituted with non-halogen the toxicity drops

arttaches at what rate, or rather how prferentially (in various environments)?


>Exposure long enough, causes complete decomposition to carbon dioxide,
>water and HCl.  Phil Kearney of USDA, Beltsville did a micro-ecosystem
>study of carbon radio-labelled 2,3,7,8-TCDD and found that as it moved
>through the ecosystem it decomposed in the air forming, ultimately,
>radio-labelled CO2.

how complete is this Rx, how fast, and in what environments doesn't it occur?


>The time for decomposition depends on the matrix, and its ability to expose
>the dioxins to the light.  It also depends on the wavelength and intensity
>of the light.  The toxic oil which caused all the problems in Missouri was

do photol. Rx form other pcdd/f's/other Ah-binding compounds
preferentially?  to what extent do differnt pcdd/f photolize?

>An early study was done by Crosby on dioxins on the surface of leaves
>exposed to sunlight.  He found a half-life on the order of hours, as I
>recall.

again, at what product did the Rx's terminate?


>In the lab, analytical standard solutions must be protected from room light
>since, in clear vials, the concentration can drop a factor of two in one
>month.  (A personal observation)

again, to what compounds?

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