the Endometriosis Association
review of links between endometriosis and dioxin
is a puzzling and sometimes debilitating disease that affects
millions of women around the world. Women
suffering from endometriosis experience a variety of symptoms, with
lower abdominal pain being most common. Pain can be especially intense
before and during menstrual periods. Some women experience pain
throughout the menstrual cycle; some during sex. The disease forces
more than 100,000 hysterectomies each year in the United States
alone, and the costs of the disease exceed $1 billion annually.
Particularly troubling is the fact that it is showing up more than
ever before in very young women. Given the poor quality of data,
however, it is difficult to document long term trends or determine
the precise number of women afflicted with the disease. Many cases
go unreported and accurate, confirmed diagnosis requires an invasive
specialists in the field believe that the prevalence of the disease
has increased greatly since World War II. The National Institute
of Child Health and Human Development estimates that endometriosis
afflicts 10 to 20 percent of women of childbearing age in the U.S.
Prior to 1921, there were only twenty reports of the disease
in the worldwide medical literature.
develops when endometrial-like tissue starts growing in
places where it shouldn’t be, away from the lining
of the uterus, often in the abdominal cavity or pelvic region, but
sometimes in lungs or arms, and elsewhere. These tissue growths
respond to hormonal signals in the menstrual cycle in the same way
that uterine lining does, building up and breaking down each month.
But while the uterine lining can be flushed out of the body during
menstruation, the tissue remains of endometrial growths
have no place to go. Internal bleeding, inflammation and
other problems result.
these facts about endometriosis are clear, the causes of the disease
are much more obscure and debated. There are four key parts to the
how does endometrial tissue wind up in inappropriate locations?
One suggestion is that endometrial cells are transported by reverse
flow off blood during menstruation into the abdominal cavity,
or through the blood stream and lymphatic system to more remote
sites. Another is that cells in the remote locations are transformed
from their original condition into endometrial cells. These explanations
are not mutually exclusive.
why doesn’t the immune system prevent endometrial
tissue from becoming established and growing? Recent
research has revealed that women with endometriosis are also likely
to experience an array of immune system problems, suggesting that
immune system dysfunction may be the proximal cause of endometriosis.
The challenge then is to understand what has happened to the endometriosis
victim's immune system.
what would lead some women to develop severe endometriosis,
while others none at all? There appears to be some heriditary
component to the risk of endometriosis, possibly involving multiple
genes, but environmental factors are also implicated. The
most telling evidence on environment comes from animal
studies in which dioxin increases the risk of endometriosis in
Rhesus monkeys, and also increases the likelihood that endometrial
implants will thrive in rodents. Monkeys exposed to radiation
also are more likely to develop endometriosis.
fourth, what are the patterns of the disease over time?
As indicated above, it is widely believed that endometriosis is
more common now than mid-20th century, and data also suggest that
more cases are now developing earlier in life than before and
becoming more severe.
we describe in Chapter 10 of Our Stolen Future, the medical
causes of endometriosis are shrouded in uncertainty. A few studies
completed by the time we published OSF pointed toward contamination.
Since then a small number of studies have been reported consistent
with this trend. None contradict it.
1992, German scientists reported
an association between heavy PCB contamination and endometriosis
that hinted at a new chapter in the search for causes of endometriosis.
Then in 1993 researchers from the Harlow Primate Center at the University
of Wisconsin published dramatic and unexpected findings
. Their study was of monkeys used in research on the long-term reproductive
effects of dioxin. When three of the dioxin treated animals died
of severe endometriosis, a new study was initiated to compare the
presence and severity of endometriosis with the animals exposure
to dioxin. The study found a dose-dependent relationship between
dioxin and endometriosis. Animals with more exposure were more likely
to develop the disease, and the greater a female monkey's exposure
to dioxin, the greater the severity of the disease. Only one
of 7 animals exposed to 25 parts per trillion dioxin was
free of endometriosis. This was much higher than the rate of
endometriosis experienced in the general population of monkeys at
the research center, about 30%.
work has now afforded additional clues. In mice and rats, exposure
increases the size of endometriotic sites that are experimentally
induced. A furan
also promotes endometrial growth.
about dioxin and endometriosis...
we still lack scientific certainty about the causes of endometriosis,
exposures to environmental factors that undermine the immune
system are emerging as one of the most likely causative agents.
Both dioxin (and other dioxin-like compounds) and radiation harm
immune system action, in monkeys as well as in people. Widespread
exposures to dioxins increased during the 20th century, as most
likely did endometriosis. Other contaminants also are toxic to the
immune system including a variety of pesticides and industrial compounds.
combination of experimental data from animals and circumstantial
evidence from people suggests that preventative steps to
reduce exposures could assist in the fight against endometriosis.