[Dioxin-l] follow-up TCDD cancer potency/TDI history; earliest refer. to dixon?

[Tony Tweedale]

looking through my files for the earliest refer's to dioxin, I discovered
the whole of Dr Commoner's address to the 2nd Citizen's Dioxin Confer. from
which a quote was posted here (about O-Cl's ocurance in nature).  It mainly
is about the controversy & fraud of TCDD's cancer risk.  My post of a few
days ago neglected the pre-Banbury conference portion of the story, and I
recommend Commoner's speech to all.

The landmark '78 Kociba et al. TCDD rodent assay (_Tox & Applied Pharmacol.
46:279-303 -- in which 100 ng/kg/d TCDD caused cancers in almost half the
female rats, doses of 10 and 1 ng/kg/d were also given but I don't know the
results) led to EPA's '85 TDI (estimated "safe" intake) of 0.006 pg/kg/d,
for ambient water standard setting.

[See 1980's  Poland & Glover "A Model for the Mechanism of Action of
2,3,7,8-TCDD', published in the proceedings of the confer. "Estrogens in
the Env.', ed. MacLachlan of NIEHS, which I think was published in _Env
Health Perp's_, NIEHS' journal.  This is an incredible (for 1980, as is the
whole NIEHS sponsored conference) summary of the Ah mode of action of TCDD
(which mechanism is cited by propnents & opponents of weaking the TDI, as
it was by Commoner).  This paper also shows that PAHs, tho binding to Ah,
do not induce enzymes and proteins/do not get carried into the nucleus; but
TCDD and various halogenated analogues to it (ie planar and 3 X 10
angstroms in 2-D size) do.]

Commoner says a Dow scientist challanged the Kociba sudy and EPA's
resulting '85 standard.  The P&P industry's toxicologists borrowed the
microscope slides to look for cellular signs of uncontrolled growth
(cancer), and were split in opinion--resolvced by a vote (not a
conservative aproach!) to reduce the cancer potency by half.

Commoner then says EPA set up a Workgroup chaired by the Reagan AA for OR&D
(Office of Reearchs & Develpmnt.), which came out w/ an external a draft
review of the '85 RA in '87.  They chose to AVERAGE the various cancer risk
estimates -- -industry's and EPA/Kociba et al. (god scientific method!--as
Comoner points ot, one or the other models is right--it's potent or less
potent...).  The Workgroup  withdrew this estimate after external comment
(incl. from Commoner and Tom Webster) and accepted the Kociba derived one;
but finally ended up stating it may be an overestimate of risk and that the
cancer potency was 16 X's less than the '85 estimate ("unencumbered by
factual scinetific analysis", as C. puts it).

These EPA and industry reviews of Kociba led to the '90 Banbury conference
(sponsored by EPA and the Chlorine Institute, but it was industry's PR
spinners who relesed a false claim that there was consensus at the
conference that TCDD's cancer potency-->and other AH mediated effects--was
indeed less potent).  Pick up the story from that _Science_ news article I
cited in my previous post on this (in sum, EPA agreed to review dioxin-like
(TCDD-like) compounds once more, and--w/ fianlly opening the process to
scientific review --ended up essentially confirming the Kociba study,
setting the cancer TDI @ 0.01 pg/kg/d (relaxed from 0.06); but it also
based risk on cumulative exposures and on all the dioxin-like PCDD/F/PCBs,
and on non-cancer effects (as the stiill v. incomplete data allows).

To me, this history shows the critical importance of supporting science and
scientists.  This includes letting them work, accepting their claims as
possible, arguing from that basis, and encouraging openess (which incl's
publication).  Now if only industry's scientists would generally live up to
this standard of openess!
----

Commoner also gives here the earlest refer. I have about the existance of
dioxins or TCDD.  He says 2 Atlanta physicians published in '36 in _Arch
Derm. & Sypholology_ a case study of two Monsanto Anniston AL workers. One,
"O.D., a Negro aged 26 [who] began work in the distillation of chlorinated
diphenyl in April 1930."  Diphenyl is the dioxin backbone--perhaps the
plant was making DDT?  Commoner writes:  The patient had severe chloracne
and even in Dec. '33 "complained of lassitude, loss of apetite and libido."
"His complaint of lassitude was not borne out by anything nore than the
usual temperament of the Negro towards work." [!].  Elsewhere I see the
famous '65 Dow experiment of painting Pennsylvania prisoner's backs w/
dioxins (w/out consent or informed consent).  In between, internal company
(BASF, Monsanto, Dow, Hercules, etc.) dioxin studies, some studying
accidents/explosions from the '40's & '50's) began seeing the light of day
(reluctantly) by the early '70's, perhaps a bit earlier.  Commoner, CEHJ's
Carol van Strum (activist and USFS (Forest Svc)  2,4,5-T aerial victim),
EPA's Bill Sanjour, Dr. Richard Clapp, the VVA (Vietnm Vets Amer.) and
Chicago Media Watch  (Liane Casten), inter alia, have compliled the record
of early industry fraud and cover-ups on dioxin.  Commonly, the exposed
would be moved into non-exposed study groups, and vice-versa, in these
company woker studies.  All these reviews, incl Dr. Commoner's speech, are
published in _Synthesis/Generation--A Magaz. of Green Social Thought_,
Summer '95.

Does anyone have any cites mentioning dioxins bewteen 1936 (or earlier!)
and '65?
---


Casten, Sanjour and elsewhere CCHW's (now CEH&J) Steve Lester (in their
_Everyone's Backyard_:13:3), have also summarized EPA's reaction,
butressing Commoner on the Kociba saga.  V. briefly, EPA in '87 began
considering industry's detoxifying claims.  But in '90 EPA's Cate Jenkins
alerted EPA's Science Adv. Board (SAB) about such fraud by BASF & Monsanto;
SAB advised EPA continue to rely on the animal studies.  EPA then
investigated but dropped a crimminal investigation on the companies.

VP Gore has heard and repeated (Oct '95) that every breath we take has
6-times the # of Cl atoms as before WW2...

Tony Tweedale

Causality is a concept not subject to empirical demonstration. -David Hume
(1711-'76)

Temperate but endangered planet.  Enjoys weather, northern lights,
continental drift.  Seeks caring relationship with intelligent life form.
      -Friends of the Earth