dioxin human health (was Greenpeace leaked dioxin...) 
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 dioxin human health (was Greenpeace leaked dioxin...)

i was unable to post this when i wrote it, sun eve. (yesterday)


>>>This is the old bait and switch routine. You bait us by mentioning the low
>>>levels of dioxin detected in humans, then switch to the alleged effects on
>>>laboratory animals. The only problem is you failed to mention that you had
>>>switched.  The effects you allege are confined to laboratory animals, an
>>>entirely different subject,since dioxin has been known for decades to be far
>>>more toxic to our {*filter*} friends than to humans.  When you or EPA have
>>>identified harmful effects of low level exposure to dioxin in *humans*, get
>>>back to us.
>> bait & switch my a**


>Frankly, tony, your posterior anatomy doesn't interest me.  Try alt.sex.motss.
>In the mean time, perhaps you can tell us how we can obtain a copy of the
>original document.  By all means, post your summary of the highlights, but
>you'll pardon me if I reserve judgement until I read the document myself.

sorry about my language, and glad to be able to post the summary on the same
thread. there's no address given, but it should be avail from the int'l
joint commission. i got my copy from a professor.

the following extended quotes are from:
great lakes water quality board--102nd meeting, chicago il, 15 july '93
                   're-evaluation of dioxin' (19 pp's)
presentation by linda birnbaum, dir. env. toxicology division, u.s. epa

"what i would like to do today is give you an overview of the state of
science of dioxins & health effects. [the whole talk revolves around human
health effects, but she mixes freely w/ mammalian data.]

"...the issue that dioxin is but one of a family of chemicals."

"the highest level we know people were exposed to, would have been lethal in
guinea pigs, but they are, at least in the order of magnitude or more, lower
than the levels that would kill almost any other mammalian species. so i think
the reason we have not seen wasting or death in people is that we have not had
high enough exposure..."

"effects on the liver--there are some differences in species, but in general,
you see enlargement, you see accumulation of fat. in some tissues you have
hyperplasia, which is a proliferation of cells. ... in other kinds of cells
instead of getting hyperplasia, you get squamous metaplasia, which is an inap-
propriate differentiation of cells. ... not only in monkeys for example but
also in humans, is metaplasia of the meibomian glands of the eye."

"dioxin is a potent teratogen in a # of species... .in other speccies it
causes much more subtle developmental effects. ...in a standard teratology
study, you dose animals during organogenesis, which is the major period of
differentiation...and then you sacrifice them just before they would normally
be born. the developmental effects we are studying now in fact are things that
you don't see until the animal reaches puberty, and then there are altrations
in the {*filter*} functions and reproductive behavior of the animals. so if you
kill them at birth, you're not going to see what is going to happen."

"...hormones are a very carefuly modulated, and the way that we maintain ho-
meostsis in our body is by having a balanced level."

"dioxin modulates the activity of many of these [growth factors & receptors,
table 3], leading to altered growth & differentiation.

"...then the dioxin can be recycled back. ...one of the critical differences
about dioxin, compared to, for example compounds in broccoli, cauliflower &
other foods we eat that also bind to this receptor, is that those compounds
are very rapidly metabolized ang gotten rid of. the problem with dioxin is
that you have a persistant effect. dioxin comes in, binds with its receptors,
and it ties it up. sou you get a constant signal from the nucleus to make
more protein, and you have a constant phosphorylation going on. usually phos-
phorylation events are very tightly regulated. they are usually very much
on-off, and now you've locked the switch. i think that the whole idea of
the persistance of the dioxin activity is an important one..."

"you have approximately 3-5,000 fold differences in sensitivity [among
species, re:acute toxicity]. in many chemicals this is highly unusual. for
something that functions like a hormone this is not totally unexpected. ...
most mammals tend to cluster in the neighborhood of 100ug/kg as approx. the
lethal dose. ...if you look at hamster embryos or fetuses, they are essen-
tially equisensitive to guinea pig embryos. if you look at rat embryos they
are essentially equisensitive. there is something about the {*filter*} hamster
that makes them resistant to tcdd..."

"in the ongoing...(niosh) looking at workers who were exposed to dioxin, these
{*filter*} males are showing decreases in...testosterone at body burdens very simi-
lar to the body burdens in {*filter*} rats. in immunotoxicity testing, human lym-
phocytes & cultured cells respond to the same concentration of dioxin in the
medium as mouse & monkey cells. ...developmental toxicity based on organ
culture you find similar response at similar concentrations of tcdd... simi-
larly, the body burden associated w/ chloracne in people is essentially the
same...in monkeys, hairless mice, or rabit ears... cancer appears to occur
at similar body burdens in animals as in humans."

"we have since repeated that [peterson, u. wisconsin, as low as 65 ng/kg
doses] study, not only with his kinds of rats... we have also looked at
hamsters...basically the same results" [decreased {*filter*}, altered {*filter*}
behavior, deformed {*filter*}ia].

"the yucheng cohort [2,000 taiwanese who cooked w/ oil contaminated w/ pcb's
& pcdf]...the children born following this episode have been followed for the
past 8-133 years, that is the age of the kids now. ...ectodermal dysplasia
...short in stature...developmentaly delayed...their iq is [permanently, so
far] shifted about 5 points down... the ones who are 10-13 are apparantly
having problems w/ their {*filter*}ia. this is very new data..."

"...if you feed animals in long-term studies w/out ading any known initiator,
dioxin by itself still causes an incr. in tumors. it does not cause only
one type of tumor, it causes tumors at multiple sites. it causes it in both
males & females..."
"seveso cohort...very significant increases in multiple tumor types... there
is also a decrease in {*filter*} cancer. remember is told you dioxin is a hormone,
and it may increse some things and decrease other things. the decrease in
{*filter*} cancer, btw, has been reported in animal studies. ...seveso...the in-
crease is in both males and females, and again at multiple sites. ...to me,
the data is overwhelming that dioxin has the potential, at least at high
doses, to result in cancer in people."
[tables 5 & 6, summarize 18 cancer mammal (rats, mice, hamsters) studies, all
positive, 1 medaka fish study showing multiple site tumors w/ high incidence
& short latency, 3 recent human epidemiological cohort studies for cancer,
all corelated exposure level w/ increased incidence, showed generalized
tumor response, especially in people who were exposed long term]

"in the northern quebec inuit population exposed to very high levels of pcb
...,children also have v/ high incidence of respiratory infenctions and
otis, and also a very decreased rate of take of vaccinatins. all which would
at least be compatible w/ the effects on the immune system."

[3 endometriosis (tissue build up in the uterus) in monkey studies, all show-
ing dose-response relationship w/ dioxin or pcb 1254 (the most tcdd like pcb
mixture). endometriosis is newly epidemic in humans]

"so i think at this point, in the general scientific community, there are 3
consensus points... i) that dioxins are growth dysregulators that are mediated
through the Ah receptor; ii) that people are sensitive to the effects of di-
oxin; iii) and if you are going to look at the env. risk from these compouns,
you need to consider all the related isoteric compoounds."

"i can't tell you yet whether tumor promotion or immunotox. or develop. tox.
may have thresholds or not. but...simple biochemical responses are occuring
in the same range of body burden as develop. and immuno toxicity. and in that
range there is no evidence for a threshold or nonlinear response. the other
point...is that...we are not ever starting from zero esposure. we all have
these compounds in our body."

"what we see are great similarities across species, and that there may be
sensitive subpopulations, based on either exposure or susceptibilty."

"we have been doing a lot of data collection, because what we wanted to do
was try to develop extrapolation models that would be biologically based."

"so, what were the results of last september's [epa dioxin re, re, as{*filter*}t]
review? well, the outside panel, at that point, said that the body burden in
the general population was at or near the level were responses are expected
to occur. i am going to editorialize, and i am not speaking for the agency,
but this sounds to me that this has a direct impact on a regulatory agenda.
thank you."

[from the q&a session]

"now those ranch handers [vietnam agent orange cohort] come back every 5
years...going to see a lot more information out of the seveso cohort...
we need to look at the right population, & i don't think it's {*filter*} males
[probably re: occupational exposure cohorts]. i think we need to be looking
at {*filter*} females and we need to be looking at children born to women who were
exposed and we need to follow those kids, especially for when they hit pu-

"on the last day of the peer review, they actually sat there & listed effects
and they listed body burdens that were associated with the effects in animals,
and...in people. ...the levels of dioxin by itself, are probably not that
high. but when you look at the sum total of what is out there...high enough so
you might say we are having a response." [followed by an interesting off-the-
record statement]

tony tweedale

Sat, 09 Nov 1996 03:12:27 GMT
 [ 1 post ] 

 Relevant Pages 

1. Study Of Dioxin-Exposed Humans

2. ARTICLE: Study Of Dioxin-Exposed Humans

3. ARTICLE: DIOXIN linked to health

4. Dioxins and Pregnancy

5. Dioxin and Native Communities

6. Dioxin & PCB Pollution: An Update

7. RACHEL: Dioxin Reassessed, #2


9. RACHEL: Dioxin Reassessed, #1

10. Dioxin and endometriosis

11. Rachel: DIOXIN

12. Test for dioxin exposure

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