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Re: Does dioxin toxicity increase in the environment??
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- Subject: Re: Does dioxin toxicity increase in the environment??
- From: "Rebecca Leighton Katers" <firstname.lastname@example.org>
- Date: Sat, 2 Aug 1997 13:54:50 +0000
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I've always wondered if the more toxic congeners
of PCBs, furans and dioxins might be accumulating while
the total levels appear to be dropping.
In the Lake Michigan region, agencies claim progress is
being made because PCBs have dropped dramatically
since the 1970s.
But the more toxic PCBs accumulate in the fatty
layers of aquatic wildlife in Lake Michigan, and
as one organism dies another eats its body. Is
it possible that this cycling and storage
mechanism actually protects and preserves the
most dangerous chemicals, while the less toxic
types are exposed and degraded by the elements?
Is it possible that the actual toxicity of the total remaining
chemicals in the Lake Michigan food chain is actually
much higher now and will continue to grow?
If this is true, and the other speculation about
less toxic congeners degrading into more toxic
congeners is true --- then progress will be even
Does anyone know of research data on this?
Date: Sat, 2 Aug 1997 07:35:10 -0400 (EDT)
From: Alan Watson <email@example.com>
To: Multiple recipients of list <firstname.lastname@example.org>
Subject: Re: Does dioxin toxicity increase in the environment??
My earlier post was incomplete and lacked these references - sorry:
Some work has been done on photolytic degradation to potentially more
toxic congeners by:
Miller, G.C., Herbert,V.R. Mueller, M., Mitzel, R., Zepp, R.G. (1989).
Photolysis of octachlorodibenzo - p- dioxin on soils: Production of
2,3,7,8 - TCDD. Chemosphere, 18,1265
Bueser, H.R. (1976) Preparation of qualitative standard mixtures of
polychlorinated dibenzo-p-dioxins and dibenzofurans by ultraviolet and
irradiation of the octachloro compounds. J. Chromatography., 129,303.
Bueser, H.R. (1979) Formation and Identification of tetra- and
pentachlorodibenzo-p-dioxins from photolysis of two isometric
Whilst these tend to be accelerated lab studies with high UV input it
seems plausible that similar reactions could take place in the
environment over longer periods of time.
Could it be possible, for example, that an increase in TEQ in the
environment could explain some of the discrepancies between current
emission and deposition inventories?
If this does happen how can you possibly regulate dioxin emissions on a
TEQ basis - the limits would be meaningless in real terms.
Any comments on this would be greatly appreciated!
_\\|//_ Alan Watson C.Eng
(' O^O ') Oakleigh
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