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Re: Background Dioxin Levels?
Dioxin is not natural in soil and there are still places where soil
samples can be taken and the analysis will come back all non detects.
One reference illustrating this is Jay Van Oostdam _Dioxins and Furans
in the BC Environment_ (BC MoE 1995). Many samples were taken in this
study, and mostly around known sources, yet there were still non detects
for all congeners.
What is really meant by "background"? How stable should the background
be? When looking at a single primary source, background can include
all the dioxin slowly but continuously diffusing from all the other
sources. This may be used to justify increasing levels, but really,
Another point to watch when interpreting background is how non detects
contribute to TEQ; nd=0, nd=0.5dl or sometimes a more complex procedure.
When not much is being detected, and among few samples, this is quite
significant. Using nd=0.5dl, a backgound of 1 or 2 pg/g may be
posited when there was no real detection.
Philip Fleischer email@example.com