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#414 - Potent Immune System Poison: Dioxin, 02-Nov-1994

The immune system is a complex set of specialized cells and organs that
defends the body against attack by "foreign" invaders. When it
functions properly, the immune system fights off diseases caused by
bacteria, viruses, fungi, parasites, and cancer cells. "When it
malfunctions, however, it can unleash a torrent of diseases, from
allergy to arthritis to cancer to AIDS," according to the federal
National Institutes of Health (NIH).[1]

At the heart of the immune system is the ability to distinguish between
self and nonself. A healthy immune system protects the "self" and
attacks only the "nonself." Virtually every cell in your body carries
distinctive molecules that identify it as self. Cells lacking a "self"
marker are quickly perceived as "foreign," attacked, and eliminated by
the immune system.

The National Institutes of Health (NIH) describes the immune system
this way: "The immune system, which equals in complexity the
intricacies of the brain and nervous system, displays several
remarkable characteristics. It can distinguish between self and
nonself. It is able to remember previous experiences and react
accordingly: once you have had chicken pox, your immune system will
prevent you from getting it again. The immune system displays both
enormous diversity and extraordinary specificity: not only is it able
to recognize many millions of distinctive nonself molecules, it can
produce molecules and cells to match up with and counteract each one of
them. And it has at its command a sophisticated array of weapons.

"The success of this system in defending the body relies on an
incredibly elaborate and dynamic regulatory-communications network.
Millions and millions of cells, organized into sets and subsets, pass
information back and forth like clouds of bees swarming around a hive.
The result is a sensitive system of checks and balances that produces
an immune response that is prompt, appropriate, effective, and self-
limiting."[1]

The immune system can fail in two ways: if it is damaged, it can fail
to attack foreign invaders, and can thus allow infections or cancers to
develop. On the other hand, if the immune system fails to distinguish
self from nonself, it can overreact and attack the self, causing
"autoimmune" diseases such as arthritis, asthma, lupus, or Type I
diabetes (insulin-dependent diabetes mellitus). Other autoimmune
diseases include scleroderma, Graves' disease, Addison's disease,
Hashimoto's disease, myasthenia gravis, lymphocytic adenohypophysitis
(also called Sheehan's syndrome), mucocutaneous candidiasis, Schmidt's
syndrome, and autoimmune thyroid disease.

Dioxin: Potent Immune System Poison

U.S. Environmental Protection Agency's (EPA's) 1994 draft reassessment
of dioxin emphasized that dioxin damages the immune system directly and
indirectly. From studies of rats, mice, guinea pigs, rabbits, cattle,
marmosets, monkeys, and humans, EPA concludes that even low doses of
dioxin attack the immune system. Dioxin directly reduces the number of
B cells (immune cells that develop in the bone marrow, then circulate
throughout the blood and lymph, fighting off invaders). And it reduces
the number of T cells (immune cells that develop in the thymus, then
circulate throughout the body, attacking invaders), but dioxin's attack
on T cells seems to be indirect. EPA says, "One potentially important
indirect mechanism is via effects on the endocrine system. Several
endocrine hormones have been shown to regulate immune responses,
including glucocorticoids, sex steroids, thyroxine, growth hormone, and
prolactin. Importantly, TCDD [dioxin] and other related compounds have
been shown to alter the activity of these hormones."[2,pg.9-49]

EPA goes on to say, "It is important to consider that if an acute
exposure to TCDD even temporarily raises the TCDD body burden at the
time when an immune response is initiated, there may be a risk of
adverse impacts even though the total body burden may indicate a
relatively low average TCDD level." In other words, a single dose of
dioxin at the wrong time may damage your immune system's ability to
protect you.

EPA then says, "Furthermore, because TCDD alters the normal
differentiation of immune system cells, the human embryo may be very
susceptible to long-term impairment of immune function from in utero
[in the womb] effects of TCDD on developing immune tissue." In other
words, dioxin can prevent the immune system from developing properly in
an unborn child, with lifelong consequences, EPA believes. "Animal
studies suggest that some immunotoxic responses may be evoked at very
low levels of dioxin exposure," EPA says.[2,pg.9-50]

Linda Birnbaum, director of research at the U.S. EPA Health Effects
Laboratory in Research Triangle Park, N.C., was the leader of EPA
scientific team reassessing dioxin. She says, "Dioxin appears to be a
carcinogen in fish, rodents, and other mammals, including humans. But
dioxin can also modulate [modify] the immune system resulting in an
inability to fight disease. It is a very powerful immunosuppressant.
But it can also upregulate [excite] the immune system so that you start
becoming hypersensitive, developing autoimmunity and allergies.
Depending upon the stage [of growth] of the animal and the species,
sometimes you observe immunosuppression and in other cases you observe
upregulation."[3,pg.4]

Birnbaum goes on to describe Taiwanese children, exposed to dioxin-like
chemicals, who had unusually frequent respiratory infections and ear
infections (otitis). Further, she described an Inuit population in
Quebec with elevated levels of dioxin in their bodies from eating the
fat of marine mammals (seals); their children have "very high
incidences of respiratory infections and otitis [ear infections], and
also a very decreased take of vaccinations," Birnbaum says.[3],pg.11 In
other words, vaccinations don't work well in these children, perhaps
because their immune systems have been damaged.

Birnbaum says there is no threshold for immunotoxic responses to
dioxin;[3,pg.14] in other words, there is no level of dioxin below
which the immune system is not affected. Put another way: any amount of
dioxin seems to do some damage to the immune system, at least in
animals; there is no "safe" dose.

In laboratory mice, a single tiny dose of dioxin causes increased
deaths when the mice are challenged with an influenza virus.[4] It is
worth emphasizing that the effective dose of dioxin is very small: 10
nanograms of dioxin per kilogram of bodyweight (10 ng/kg) harms the
mouse immune system enough to increase the death rate from influenza
virus. To get 10 ng/kg into perspective, consider that a single 5-grain
aspirin tablet taken by a 150-pound adult is a dose of 4.7 MILLION
nanograms of aspirin per kilogram of bodyweight (4,761,936 ng/kg). For
an adult human to get a dose of aspirin equivalent to the dose of
dioxin that harms the mouse immune system, you would have to divide a
single aspirin tablet into 470,000 pieces (nearly half a million
pieces) and eat only one piece. Is the human immune system as sensitive
to dioxin as the mouse's? No one yet knows.

What about animals more human-like than mice? Tom Webster of the Boston
University School of Public Health cites evidence that the number of
immune cells in rhesus monkeys is changed by a dioxin body burden of
270 ng/kg; in marmosets, the number of immune cells is changed at only
6 to 8 ng/kg of dioxin. "While the medical implications of this effect
are unknown, it appears to occur at about the average human body burden
of dioxin-like compounds," he says. In other words, average residents
of North America carry 7 to 9 ng/kg in their bodies now, and 6 to 8
ng/kg alters the immune systems of marmosets.[4,pg.8] "Similar effects
[immune cell alterations] were seen in the children of mothers who
lived in dioxin-contaminated Times Beach, Missouri during and after
pregnancy," Webster notes, citing work by Gerson Smoger and others.
[4,pg.7]

This past summer, German researchers published a study of the health of
158 chemical workers who had been exposed to dioxin in 1953 during an
industrial accident at a BASF chemical plant.[5] The 158 exposed
workers were compared to 161 unexposed workers. The dioxin-exposed
workers experienced more frequent infections and parasitic diseases
during the 36 years after exposure, consistent with immune system
damage. Especially noticeable were increases in respiratory infections,
thyroid diseases, disorders of the peripheral nervous system, and
appendicitis. Mental disorders were also increased. All together, the
highly-exposed group had 18% more recorded episodes of illness than the
control group.

Ironically, the largest source of dioxin entering the environment today
is medical incinerators. Together, medical incinerators and municipal
solid waste (msw) incinerators account for 95% of all dioxin emissions
into the air of the U.S., according to U.S. EPA.[6,pg.2] The good news
is: these technologies are not needed and could be phased out rapidly,
if public health authorities began to take their DISEASE PREVENTION
responsibilities seriously. Plans for new incinerators could be easily
abandoned. For both medical wastes and municipal wastes, alternatives
already exist that are cleaner, safer, and less expensive. (The chief
appeal of incinerators is political: massive campaign contributions by
the waste industry.)

Unfortunately, instead of planning to phase out incinerators, EPA has
announced plans to "regulate" incinerator emissions more tightly by
requiring air pollution scrubbers. Scrubbers will not decrease dioxin
production, but will move dioxin from the air emissions into the
incinerator ash, which gets buried in shallow pits in the ground. Thus,
current public health policies are creating a legacy of unpleasant
surprises for our children.

--Peter Montague

=====

[1] Lydia Woods Schindler, UNDERSTANDING THE IMMUNE SYSTEM [NIH
Publication No. 88-529] (Bethesda, Md.: National Institutes of Health,
July, 1988), pg. 1.

[2] U.S. Environmental Protection Agency, HEALTH ASSESSMENT DOCUMENT
FOR 2,3,7,8-TETRACHLORODIBENZO-p-DIOXIN (TCDD) AND RELATED COMPOUNDS.
VOL. III OF III. [EPA/600/BP-92/001c] (Cincinnati, Ohio: U.S.
Environmental Protection Agency, August, 1994.) This is the official
draft of "Chapter 9" of the EPA dioxin reassessment, also known as the
"risk characterization chapter." Available free while supplies last;
telephone (513) 569-7562 in Cincinnati.

[3] Linda Birnbaum, GREAT LAKES WATER QUALITY BOARD 102ND MEETING,
CHICAGO, ILLINOIS, JULY 15, 1993, PRESENTATION BY LINDA BIRNBAUM, U.S.
EPA (Washington, D.C.: International Joint Commission, Great Lakes
Water Quality Board, Dec. 21, 1993), pg. 4. Available from us for
$4.00.

[4] Tom Webster, DIOXIN AND HUMAN HEALTH: A PUBLIC HEALTH ASSESSMENT OF
DIOXIN EXPOSURE IN CANADA (Boston: Boston University School of Public
Health, 1994), pg. 7, citing unpublished work by Linda Birnbaum and
others. Available from us for $4.00.

[5] Andreas Zober and others, "Morbidity follow up study of BASF
employees exposed to 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) after a
1953 chemical reactor incident," OCCUPATIONAL AND ENVIRONMENTAL
MEDICINE Vol. 51, No. 7 (July 1994), pgs. 479-486.

[6] Lynn Goldman, STATEMENT OF LYNN GOLDMAN, M.D., ASSISTANT
ADMINISTRATOR FOR PREVENTION, PESTICIDES AND TOXICS, U.S. ENVIRONMENTAL
PROTECTION AGENCY, SEPTEMBER 13, 1994 (Washington, D.C.: U.S.
Environmental Protection Agency, September 13, 1994).

Descriptor terms: immune system; morbidity; nih; dioxin; incineration;
taiwan; children; bronchitis; upper respiratory infections; basf;
occupational safety and health; times beach, mo; mo; tom webster; linda
birnbaum; gerson smoger; epa; germany; thyroid disease; appendix;
appendicitis; peripheral neuropathy; mental health; medical waste; msw;
corruption; elections; campaign finance reform; campaign contributions;