Re: Dioxins and Plants

[Byron Bodo <bodo@interlog.com>]

>
>Not exactly true about the only reason trees give off dioxin when
>burned.  Dr Gross of the University of Nebraska found dioxin in very old
>petrified trees that had burned thousands of years ago.  He also found
>dioxin in the tissue of Eskimo bodies found frozen in an igloo from
>several hundred years back.  The dioxin was thought to have come from
>burning wood for heat within the igloo.  The chlorine source for this
>was most likely salt air from the sea, but trees do contain chlorine
>from salt uptake from the soil.  I agree that the levels are higher now
>due to the organochlorines from the atmosphere.
>
>Dennis Catalano
>

There's no doubt that some of the high Kow / Koa (octanol-air
partition coefficient if anyone's actually measured such) OCs sorb into
in waxy coatings of leaves, needles, etc. & the lipids in tree bark, but
I'd expect ( & correct me if I'm wrong) that the Cl content of wood
is probably several orders higher.

Despite some claims that forest fires were major PCDD/F sources,
I've yet to see any hard evidence (e.g., dated sediment cores from remote
lakes) that confirms the assertion.  Accordingly, PCDD/Fs in the ambient
environment created by natural combustion of vegetation & wood are 
likely very low. 

-bb