I am presently reading a book called "Living Downstream: A
Scientist's Personal Investigation of Cancer and the
Environment"(1997), by Sandra Steingraber, a Ph.d biologist and
ecologist. It is extremely well-written, well-researched, and well-
reasoned. I hope that everyone taking part in this discussion will
look for it. Steingraber examines the evidence for cancer "clusters"--
areas (geographical, cultural, occupational, etc.) that have higher
rates of particular cancers compared to the general population--and
possible environmental explanations. She begins in her own county
in Illinois. I spent my own childhood in what was to become such
a cluster. When I was born in Jacksonville, Arkansas in 1970 the
town was home to a factory that produced Agent Orange. In the
early 90's, the defunct factory was cleaned up with Superfund
money. The public library has a filing cabinet documenting the
dioxin contamination of the town and the high incidence of dioxin-
associated cancers. IMO my generation and my parents' have
been involuntary "experimental" subjects.
Because I think this is a very important topic, and this information
needs to be disseminated, I've taken the time to post the following
excerpts. Please don't delete it--read it or save for later. These
quotes are taken from the first 50 pages, all I've read so far. I think
they speak well to the questions that have come up in this thread.
"There are individuals who claim, as a form of dismissal, that links
between cancer and environmental contamination are unproven and
unprovable. There are others who believe that placing people in
harm's way is wrong--whether the exact mechanisms by which this
harm is inflicted can be precisely deciphered or not. At the very
least, they argue, we are obliged to investigate, however imperfect
our scientific tools: with the right to know comes the duty to inquire.
"Happily, the latter perspective is gaining esteem as many
leading cancer researchers acknowledge the need for an
"upstream" focus. As explained at a recent international
conference, this image comes from a fable about a village along a
river. The residents who live here, according to a parable, began
noticing increasing numbers of drowning people caught in the river's
swift current and so went to work inventing ever more elaborate
technologies to resuscitate them. So preoccupied were these
heroic villagers with rescue and treatment that they never thought
to look upstream to see who was pushing the victims in.
"This book is a walk up that river.
"When all the diagnoses of years past and present are tallied, an
ongoing narrative emerges that tells us how the incidence of cancer
has been and is changing. Changes in cancer incidence, in turn,
provide key clues about the possible causes of cancer. For
example, if heredity is suspected as the main cause of a certain
kind of cancer, we would not expect to see its incidence rise
rapidly over the course of a few human generations because genes
cannot increase their frequency in the population that quickly. Or if
a particular environmental carcinogen is suspected, we can see if a
rise in incidence corresponds to the introduction of such
substances into the workplace or the general environment (taking
into account the lag time between exposure and onset of disease).
Such an association does not constitute absolute proof, but it gives
us ground to launch additional inquiries.
"The work of compiling statistics on cancer incidence is carried
out at a network of cancer registries, which exist in the U. S. at
both the state and the federal levels. Theoretically, for each new
cancer diagnosis, a report is sent to a registry [containing] a coded
description of the type of cancer; the stage to which it has
advanced; and the geographic region, age, sex, and ethnicity of the
newly diagnosed person.
"This incoming information is then processed, analyzed,
audited, graphed, and disseminated by teams of statisticians. In
and of itself, a head count is not very useful. The prevalence of
cancer is higher now than it was a century ago, in part because
there are simply more people now. There are also proportionally
more older people alive now than ever before, and the aged tend to
get more cancer than the young. Between 1970 and 1990, for
example, the U.S. population increased by 22 percent, and the
number of people over sixty-five increased by 55 percent. To
eliminate the effects of the changing size and age structure of the
population, cancer registries standardize the data. One way of
doing this is to calculate a cancer incidence rate, which is
traditionally expressed as the number of new cases of cancer for
every 100,000 people per year. For example, in 1982, 90 out of
every 100,000 women living in the state of Mass. were diagnosed
with breast cancer. By 1990, the incidence rose to 112 out of
100,000.
"These numbers are also age-adjusted. That is, the data from
all the differently aged people from any given year are weighted to
match the age distribution of a particular census year. Thus
standardized, the statistics from various years can be compared to
each other. In this way, we know that the 24 percent rise in breast
cancer in Mass. that occurred between 1982 and 1990 did not
happen because the population of New England women was aging.
Alternatively, cancer registry data can be made age-specific: the
percentage of 45- to 49-year-olds contacting breast cancer can, for
example, be compared with the percentage from a decade ago...
"While still a matter of some debate, the most widely accepted
estimate is that between 25 and 40 percent of the recent upsurge
in breast cancer is attributable to earlier detection. Underlying this
acceleration exists still a gradual, steady, and long-term increase
in breast cancer incidence...This slow rise--between 1 and 2
percent each year since 1940--predates the introduction of
mammograms as a common diagnostic tool. Moreover, the groups
of women in whom breast cancer incidence is ascending most
swiftly--blacks and the elderly--are among those least served by
mammography. Between 1973 and 1991, the incidence of breast
cancer in females over 65 in the United States rose nearly 40
percent, while the incidence of breast cancer in black females of all
ages rose more than 30 percent.
"All types combined, the incidence of cancer in the U.S. rose 49.3
percent between 1950 and 1991. This is the longest reliable view
we have available. If lung cancer is excluded, overall incidence still
rose by 35 percent. Or, to express these figures in another way: at
midcentury a cancer diagnosis was the expected fate of about 25
percent of Americans...while today, about 40 percent of us (38.3
percent of women and 48.2 percent of men) will contract the
disease sometime within our lifespans. Cancer is now the second
leading cause of death overall...More of the overall upsurge has
occurred in the past two decades than in the previous two.
"...[W]hile smoking remains the largest single known preventable
cause of cancer, the majority of cancers cannot be traced back to
cigarettes. Indeed, many of the cancers now exhibiting swift rates
of increase--cancers of the brain, bone marrow, lymph nodes, skin,
and testicles, for example--are not related to smoking. Testicular
cancer is now the most common cancer to strike men in their
twenties and thirties. Among young men both here and in Europe,
it has doubled in frequency during the past two decades. These
increases cannot be attributed to improved diagnostic practices.
Brain cancer rates have risen particularly among the elderly.
Between 1973 and 1991, brain cancers among all Americans rose
25 percent. Those over sixty-five suffered a 54 percent rise.
"Mortality and incidence do not always track each other. No
cancers are increasing in mortality while decreasing in incidence,
but several cancers have increased in incidence even as their death
rates have declined due to more effective treatments. According to
SEER data, these include cancers of the ovary, testicle, colon and
rectum, bladder, and thyroid. There are eight cancers whose
incidence and mortality are both on the decline: those of the
stomach, pancreas, larynx, mouth and pharynx, cervix and uterus,
as well as Hodgkin's disease and leukemia...
"However, these modest gains are swamped by the cancers
that show both increasing incidence and increasing mortality:
cancers of the brain, liver, breast, kidney, prostate, esophagus,
skin (melanoma), bone marrow (multiple myeloma), and lymph
(non-Hodgkins lymphoma) have all escalated over the past twenty
years and show long-term increases that can be traced back at
least forty years.
"...'Explanations for these increases do not exist,' according to
Philip Landrigan, a pediatrician and leading public health
researcher...Clarification about carcinogins, Landrigan believes,
requires an environmental line of inquiry:
'The possible contribution to recent cancer trends of the substantial
worldwide increases in chemical production that have ocurred since
World War II (and the resulting increases in human exposure to
toxic chemicals in the environment) has not been adequately
assessed. It needs to be systematically evaluated.'"
"I am struck...by the symmetry between Landrigan's recommended
course of action and an observation made thirty years earlier by
two senior scientists at the National Cancer Institute, Wilhelm
Hueper and W.C. Conway: 'Cancers of all types and all causes
display even under already existing conditions, all the
characteristics of an epidemic in slow motion.'...And yet the
possible relationship between cancer and what Hueper and
Conway called 'the growing chemicalization of the human economy'
has not been pursued in any systematic, exhaustive way.
"...The rise in cancer incidence over calendar time is one line of
evidence that implicates environmental factors. The increase in
cancer incidence among successive generations is another. A
third line of evidence comes from a close cosideration of the
cancers that exhibit particularly rapid rates of increase. If we
restrict our view to these cancers, what patterns emerge?
"...Melanoma accounts for only 5 percent of all skin cancers, but it
is the most dangerous kind, accounting for 75 percent of skin
cancer deaths. The U.S. incidence of melanoma rose nearly 350
percent between 1950 and 1991, and mortality rose by 157
percent. Between 1982 and 1989 alone, melanoma incidence
jumped 83 percent...The accelerating incidence of melanoma
means exposure to ultraviolet radiation is probably increasing. This
could be happening for two reasons. First, more people are
spending more time in the sun. Second, the sunlight to which we
are exposed contains more ultraviolet rays.
"...While the incidence of Hodgkin's disease has declined modestly
over the past two decades, non-Hodgkin's lymphoma has shot up--
approximately tripling in incidence since 1950. This increase is
evident in both sexes and within all age groups except the very
young...Lymphomas do seem to be consistently associated with
exposure to synthetic chemicals, especially a class of pesticides
known as phenoxy herbicides [including 2,4,5-T and 2,4-D, and the
combination of these two, Agent Orange].
"...Multiple myeloma is also associated with exposure to a variety
of chemicals--metals, rubber, paint, industrial solvents, and
petroleum. Farmers and agricultural workers exposed to
pesticides and herbicides have higher rates of multiple myeloma
than the general population. Multiple myeloma is on the rise in all
major industrialized countries. But the parallel increase among
both sexes argues against a purely occupational cause.
According to one researcher who has examined multinational
mortality trends, the patterns of multiple myeloma among
generational cohorts suggest a general environmental exposure of
some kind, common to all industrialized countries...
"...The spatial features of cancer's occurrence around the globe
clearly belie the notion that cancer is a random misfortune.
Industrialized countries have disproportianately more cancers than
countries with little or no industry (after adjusting for age and
population size). One-half of all the world's cancers occur among
people living in industrialized countries, even though we are only
one-fifth of the world's population. Closely tracking industrialization
are breast cancer rates, which are highest in North America and
northern Europe, intermediate in southern Europe and Latin
America, and lowest in Asia and Africa. Breast cancer rates are
thirty times higher in the U.S. than in parts of Africa, for example.
Breast cancer incidence in the U.S. is five times higher than it is in
Japan, though this gap is rapidly narrowing. Of all the world's
nations, Japan has the most rapidly rising rate of breast cancer.
"Because we have no nationwide cancer registry, we also have no
definitive geography of cancer incidence in the U.S. The National
Cancer Institute has, however, published the two-volume 'Atlas of
U.S. Cancer Mortality among Whites and Nonwhites: 1950-1980'--
in essence, cancer death maps. Areas of high mortality are
colored in scarlet, fuchsia, and orange; areas of unusually low
mortality are painted deep blue...
"Death from cancer is not randomly distributed in the U.S.
Shades of red consistently light up the northeast coast, the Great
Lakes area, and the mouth of the Mississippi River. For all
cancers combined, these are the areas of highest mortality; they
are also the areas of the most intense industrial activity."
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