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Dioxin and PCB update in Belgium

c. miller rellim at MAILHOST.TCS.TULANE.EDU
Mon Jun 7 09:25:51 EST 1999


I suggest that you refer to these documents at American Toxic Substances
and Disease Registry (ATSDR) within the Center for Disease Control (CDC)
for information on health effects and potential risks due to PCB and dioxin
exposure.

http://www.atsdr.cdc.gov/atsdrhome.html (general information)
http://www.atsdr.cdc.gov/mrls.html (minimal risk levels)
http://www.atsdr.cdc.gov/tfacts104.html (updated dioxin fact sheet)

In my opinion, the toxicity of dioxins and PCBs is overrated by some
government agencies, risk assessors, epidemiologists, and toxicologists. I
agree that they can cause cancers, hepatotoxicity, endocrine disruption,
immunotoxicity, behavioral and developmental effects given the proper
conditions (sensitive animal strains, sufficient doses, etc.). However, the
human epidemiological evidence for toxicity is surprisingly weak for "the
most toxic man-made compounds known". Humans may be relatively insensitive
to TCDD due to the nature of the human dioxin receptor. The human receptor
(common to >99% of the population) has a relatively low affinity for TCDD
and other toxic ligands, which probably protects us from the ambient low
levels of these contaminants. As suggested in your post, the fat pool in an
organism can serve as a reservoir for PCBs and dioxins, thus keeping the
compounds sequestered from more critical target tissues. I don't mean to
sound as if exposure to these (or any) chemicals is not significant--it
is--and should be avoided if possible. I think that there is cause for
concern (but not panic) when exposures  happen.

I suggest that the best efforts be directed to prevent future exposure as
this is the easiest and most cost effective approach to controlling the
problem. Following this, some estimates of dose will be needed before any
reasonable predicitions of potential heath effects can be made.


Best wishes,

Chuck


Dr. Charles A. Miller III,   rellim at mailhost.tcs.tulane.edu
Dept. Environmental Health Sciences, SL29
Tulane-Xavier Center for Bioenvironmental Research and
Tulane Univ. School of Public Health and Tropical Medicine
1430 Tulane Ave.
New Orleans, LA 70112
(504)585-6942, fax (504)584-1726
Bionet.toxicology newsgroup: http://www.bio.net/hypermail/TOXICOLOGY





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