Why then are some women more susceptible to endometriosis?
One of the most recent theories is that it may be due to individual immune deficiency caused by, among other things, immuno suppressive drugs, toxic overload from other drugs or environmental pollutants.
There is strong evidence linking endometriosis with immune system damage caused by the environmental pollutant dioxin. Research done by the US Endometriosis Protection Agency indicates a close association between dioxin levels in the body and the severity and incidence of endometriosis.
Dioxins are unintentional by products of chemical manufacturing processes involving chlorine, such as plastic, PVC, many solvents such as drycleaning fluid, pesticides and wood preservatives, disinfectants and drugs. They are produced when the waste containing these chlorine chemicals is burnt or incinerated. They then become airborne, fall on grass and plants and are eaten by animals such as cows, which become dioxin concentrators. Animal fat, such as meat and dairy produce, is the major source of dioxins for humans, and surveys of breastmilk suggest that UK dioxin levels are among the highest in the world.
It is well known that dioxins attack the immune system, and the US Environmental Protection Agency (EPA) has stated that immune system effects are likely at the levels of dioxins some of us already have in our bodies: "Some more highly exposed members of the population may be at risk. . . of decreased sperm counts, higher probability of experiencing endometriosis in women, reduced ability to withstand immunological challenge and others."
An experiment carried out on rhesus monkeys exposed to the most toxic dioxin, TCDD, concluded that "the incidence of endometriosis was directly correlated with dioxin exposure and the severity of disease was dependent upon the dose administered" (Fundamental & Applied Toxicology, November 1993).
Until the use of chlorine is reduced, the only way in which we can cut dioxins intake is by eating fewer foods containing animal fat.
Drugs administered to women for conditions other than endometriosis may also lead to an immune deficiency.
A 76 year old woman who had, for several years, been taking tamoxifen (see WDDTY vol 3, no 11) an increasingly questionable drug used in the prevention and treatment of breast cancer, died from neutropenia, a blood disease linked to immune deficiency (The Lancet, 20 August 1994).
Symptoms of endometriosis usually disappear after the menopause (either naturally or medically induced), but hormone replacement therapy, in which there is little control over the amount of estrogen released into the bloodstream, has been shown to reactivate symptoms in post menopausal women (Australian & New Zealand Journal of Obstetrics & Gynaecology, November 1992).
The anti estrogen drug clomiphene citrate (Clomid), which is used to treat infertility, may also cause endometriosis, which is somewhat ironic considering that endometriosis is also being touted as a cause of infertility. In a letter to the BMJ (24 February, 1990) John M Svigos reported that in a study group of infertile women with no previous evidence of endometriosis, 57 per cent were found to have the disease following treatment with clomiphene citrate, compared to 7 per cent in the control group.
Psychotherapeutic and gastroenteric drugs have also been shown to cause adenomyosis in mice (Life Sciences 49 (3) 201-6, 1991).