By Peter Montague
There are now more breast cancers diagnosed in the US each year (181,000) than any other cancer, and all but 1000 of these occur in the female half of the population. There are a few other cancers that occur almost as often (lung: 168,000, colon and rectum: 155,000), but these other cancers are spread among the entire population, both men and women. Breast cancer kills more than 46,000 US women each year.
The incidence of female breast cancer in the US is steadily increasing. According to the National Cancer Institute, between 1973 and 1989, among women of all ages, breast cancer incidence rose at the rate of 1.7% per year (2.1% per year among women over the age of 50). To put it most starkly, in 1960 a woman's chance of getting breast cancer in the US was one in 20; today it is one in 9.
The search for the causes of breast cancer has taken many turns. There seems little doubt that something in the environment contributes importantly to the disease because in high-incidence countries, such as the US and Germany, the death rate per 100,000 women is four times as high as it is in low-incidence countries, such as Japan. Furthermore, when Japanese women migrate to the US, within a generation their breast cancer rates begin to approach the US averages.
Several factors have been linked to breast cancer: age at which a woman's period begins (later is safer); age at which menopause occurs (earlier is safer); age at birth of first child (earlier is safer); diet (less fat and more fibre are safer); alcohol intake (less is safer); and exercise (more is safer).
These factors have a common thread: they all affect the oestrogen levels in a woman's blood stream. However, these known "risk factors" still account for only 30% of breast cancers; some 70% remains unexplained.
In the 1980s, researchers in Israel observed that the incidence of breast cancer among Israeli women decreased noticeably when chlorinated pesticides were reduced substantially in Israeli milk.
Devra Lee Davis and others have formally proposed the hypothesis that oestrogen-mimicking chemicals in the environment, including pesticides and industrial wastes, may explain the rise in breast cancer that has occurred in industrialised countries during the past 30 years (Environmental Health Perspectives, October 1993).
Recent US studies of DDT in blood and breast tissues of women who developed breast cancer have reached contradictory conclusions about the relationship of DDT to breast cancer: one found a statistically significant increase in cancer among women with elevated levels of DDT (or its by-product, DDE) in their breasts. A more recent study found slightly increased breast cancer rates among black and white women with elevated DDT and DDE in their blood, but an opposite effect among Asian women; taking all three groups together, the relationship was not strong enough to achieve "statistical significance".
Most recently, researchers with the New York state Department of Health have found that women on Long Island have a greater chance of getting breast cancer if they grew up within a mile of a chemical plant than if they lived further away.
Many environmental factors may contribute to breast cancer. One well-established factor that seems to have been missed by the news media and even by some scientists is radiation. For decades, women have been subjected to unnecessary and unnecessarily high radiation exposures by the medical community.
Dr John Gofman has recently been examining medical literature going back to the 1930s and 1940s. He has found that many physicians were fixated on a "problem" (later discovered not to be a problem) called "thymic enlargement".
The thymus is a gland in the upper chest and lower neck. In the '30s and '40s, doctors imagined that "thymic enlargement" was a common and potentially fatal problem among US children. They prescribed frequent large doses of X-rays and fluoroscopic examinations, both for diagnosis and for therapy. (Fluoroscopy is to x-rays what motion pictures are to snapshots. Fluoroscopy gives the patient a much larger dose of radiation than an X-ray.) Many doctors regularly gave X-ray treatments to newborns as a "prophylactic" measure against thymic enlargement.
In a 1948 medical article, two physicians wrote, "The obstetrician or paediatrician should accede to the wishes of the parents who want neonatal roentgenograms [X-rays] of their children. It might even be wise to administer therapeutic doses over the thymus. Whatever assurance is gained by this apparently harmless and perhaps beneficial procedure will aid in alleviating any anxiety which occasionally becomes a thymus phobia."
In a 1970 medical article, Dr Hanson Blatz looked back on his professional years, noting, "Those of you who have been in the field a long time know it was once the practice of pediatricians to fluoroscope babies and young children every month and when they had the annual checkup. When we questioned this practice, physicians would say, 'Well, the parents expect it. They think if I don't fluoroscope the patients, they are not getting a complete examination.'" Gofman notes that Blatz must be describing habits of the 1940s and 1950s.
Gofman points out that, between 1920 and 1960, unnecessary and/or excessive X-rays and fluoroscopic exposures of the breasts were received by girls and women in connection with scoliosis (spinal curvature), mammograms, screening for tuberculosis, diagnosis and treatment of enlarged thymus, "therapy" for non-malignant breast conditions, monitoring of tuberculosis treatments, exposure of adults during exams of children and non-medical uses (such as fluoroscopes in shoe stores).
What should a reasonable and prudent person conclude from all this? Is radiation important in causing breast cancer? Without a doubt. Is DDT? Probably yes. Are other chlorinated compounds besides DDT? Probably yes. Does anyone know for sure about harmful effects of these chemicals? No.
What should we do to protect ourselves and our children during the decades that it will take for scientists to learn some of the answers? Adopt the precautionary principle. Avoid exposing yourself to exotic chemicals and technologies. Eat lots of fruits and vegetables, especially the dark greens and dark yellows. Prevent pollution: phase out chlorine and stop adding to the world's burden of radiation-producing materials derived from nuclear power and nuclear weapons. Trust your own common sense and don't leave important decisions exclusively in the hands of the "experts".
[From Rachel's Hazardous Waste News (US).]