[Dioxin-l] "normal background level"

[david bell]

Hi Connie

>Have you had any experience working on environmental issues with
>politicians?  If  "no politician can ignore the logic" then we wouldn't
>still be discussing dioxin and incineration<snip>

if I can try to paraphrase your line of reasoning, I think I would agree 
with you; I understand you to be agreeing about the value and utility of 
fact-based argument, but them dang' politicians are mighty slippery beasts !

>Run a CFCs time line versus a dioxin/incineration time line.  My memory is
>not perfect on this issue but I think the dioxin/incineration relationship
>came to be know first.  Why is it so far from being fixed ? <snip>
>Also if you remember there were a core of
>scientists that swore the whole CFC hole was a fabrication.  It was just
>because industry and environmentalists pulled together that the job got
>done.

I think I will vary with you here. My understanding, and it is fairly clear, 
is that there was an overwhelming scientific consensus that CFCs were a 
clear and present danger. I believe that there are reports from the National 
Academy of Sciences, etc. Scientific journals like Nature and Science were 
very clear on this, and while there was debate on the size of the hole, 
whether it was 'natural' or not, etc., it rapidly became impossible to state 
that the hole was a fabrication or, that CFCs were not plausibly involved. 
This was the basis for incredibly convincing argument.

I think you are right about some of the practical problems which you raised 
about the difficulties of reducing dioxin emission, but for my money, I 
would point out to you that there is considerable lack of consensus about 
the 'safe' level for dioxin. For example, Canada and the UK have an 
Tolerable Daily Intake (for TCDD) 1000 fold bigger than in the US; the WHO 
limit is 100-400 x bigger than the US TDI. The point I am making (without 
taking sides !!) is that there is no clear scientific consensus.

>I didn't get into the sedcore file as it would take download time and it
>seemed from your statement that again they didn't tell you why the dioxin
>was there to begin with. I do not know what industry was on these lakes or
>where they were, but I'd bet that they had bleached paper mills on them.

The stated aim of the papers was to find out about the 'background' level of 
dioxin contamination of the environment, rather than to look at pollution 
associated with particular paper mills. Nonetheless, you are quite right 
that there may have been paper mills there; I don't recall reading anything 
about that.

Given the recent postings about production of dioxins from uncontrolled 
burning, it may well be that the level of dioxin in the 1800s largely 
stemmed from the incineration that the local populace undertook. It clearly 
wasn't the chemical industry.

cheers
david


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