[Dioxin-l] Open List?

[david bell]

Hi Ralph

>Dr. Linda Birnbaum says:
>"When was dioxin first found in the environment, and when did it start
>to accumulate? <snip>Prior to
>the onset of heavy uses of chlorinated organics in industry, which
>really commenced about 1930, levels were extremely low <snip>

This was disappointing, because there are no references, and so you cannot 
find out what data she is using to make such statements.

You can look on the web at EPA data.
http://www.epa.gov/ncea/pdfs/sedcore.pdf
Finds 6 to 10-fold difference from 1970s to 1880s. See also:
http://www.epa.gov/ncea/dei.htm

This seems good data; also look at chapter 3 of 'Dioxins and Health' by 
Arnold Schecter. There is quite a bit of information that you can measure 
dioxins at 10-20% of current levels in the 19th century.

<snip>
>On whether there is a threshold for dioxin Dr. Birnbaum said;
>         “there is no threshold for immunotoxic responses to dioxin."

The EPA assessment of dioxin does not make this statement : instead it says 
that the data shows no apparent threshold. An enormous difference, as the 
second statement implies that there may well be a threshold at a lower dose.

>
>Human studies
>         Industrialists have maintained humans are not as sensitive as
>animals to dioxin. Research shows this is not strictly true.<snip> >Cancer 
>appears to occur at similar body
>burdens in animals as in humans.[5]

The current position of the US NTP is that there is insufficient, or 
limited, evidence that TCDD is a human carcinogen. Given that it is not 
clear that TCDD causes cancer in humans, how can you then compare that to 
the known cancer-causing potency in rats ? Even if you took as gospel the 
conclusion that TCDD does cause cancer in humans, the uncertainty 
surrounding how much cancer it causes means that you could only compare it 
and say it was similar within an order of magnitude.

>
>Unfortunately much of the public, especially those threatened with waste
>to energy incinerators are being hoodwinked into accepting today's
>dioxin contamination level of the globe as 'the normal background
>level.'

I don't believe I have heard anyone advocate that- is this your belief ? I 
think the current levels should diminish.

<snip>
cheers
david

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