blogsite has reported that a river resident has lived on the Tittabawassee River for 45 years and has raised six healthy
daughters. She believes that this is ample
confirmation that dioxins are not a risk to human health.
More than one Midland resident
believes that dioxins are harmless for basically the same
reasonno cancer in my family.
year, I had a conversation with a prior resident of Midland
about a "cancer cluster" in his neighborhood. In
addition to his wife that died from colon cancer, he named
at least ten neighbors that had been either diagnosed with
cancer or had died from cancer. Perhaps, his opinion
about the health risk from dioxin exposure might be
different than that of a certain river resident.
However, despite the "cancer cluster", there is no evidence
that all dioxin exposure will result in cancer.
However, there is ample evidence that
dioxin exposure is harmful to human health -- not to all
those exposed, but many.
Cancer is a disease that has affected so many that a
statistical analysis can be carried out with some degree of
certainty. While statistics can not predict who will
contract cancer, there is ample data to determine if the
incidence of cancer in larger populations is abnormally high or low.
Opponents that oppose controlling dioxin exposure to very
low levels may be basing their opinion on the assumption
that, unless there is a cancer "epidemic", dioxins are
any cancer mortality study, there is a very fine line
between a "statistically significant" linkage and a "no
causal relationship". It is amazing as to how few
deaths are needed to make the difference between the two
1991, the National Institute for Occupational Health and
Safety (NIOSH) published a study that tracked the mortality
of 5172 chemical workers that had been exposed to TCDD.
Dow's Midland plant dioxin exposed employees were included
in the study and totaled approximately 2200 workers.
The study, Cancer Mortality in Workers Exposed to
2,3,7,8-Tetrachlorodibenzo-dioxin, Fingerhut, et al,
1991, examined the mortality experience of the 5172 male
workers from 1942 to 1987.
of the cancer specific information from the study can be found on a
table that compares Standardized Mortality Ratio's (SMR)
from the NIOSH study to six Dow mortality studies. The
link to the table is
Link To NIOSH
findings from the NIOSH study are particularly interesting.
Cancer Mortality (a)
SMR 95% CI
- 130 (p<0.05)
Cancers - Rare(b)
- 241 (p<0.05)
(a) Fingerhut, et al, 1991
(b) Cancers of Other and Unspecified Sites - no ICD category
Both findings are statistically significant as
indicated by the lower 95% Confidence Interval (95% CI)
value being greater than 100.
Please be aware that a very small number of additional
deaths35.1 (Obs. 265 versus
Exp. 229.9)were all that were necessary to make the All
Cancers mortality ratio statistically significant.
a cynical person may claim that an additional 35.1 deaths
spread over 45 years over 5172 employees does seem like
muchand it's not. However, these additional deaths
are very real to the families of the deceased and they are
significant enough to confirm that dioxins are harmful to
"An unexpected finding was
the small but significant increase in mortality from all
cancers combined. The observed increase is consistent
with a carcinogenic effect of TCDD.... Moreover, a
significantly increased SMR for all cancers combined is
unusual in occupational studies of chemical workers."
NIOSH study also noted an statistically significant
elevation of Cancers of Other Unspecified Sites. The
cancers that are included in this category are the cancers
that are so rare and occur in such low numbers that
they are not assigned a specific code number in the
International Classification of Diseases.
these rare cancers, the difference between 'statistically
significant" and "no causal relationship" is even less than
in All Cancers. The NIOSH study reported the following
findings for these rare cancers: Obs. 24, Exp. 14.8, SMR
162, 95% CI 104-241. Only 9.2 additional deaths
were found over 5172 workers over 45 yearsenough to make
the elevated number of deaths statistically significant.
elevation in mortality from these rare cancers was probably
not surprising to Dow since the company has observed similar
results at the Midland plant site.
Dow Chemical Studies
Cancer Mortality - Other and Unspecified Sites
Bond, 1987 (a)
135 115-157 (Total
Bond, 1987 (a)
(a) Study is not dioxin-specificgeneral chemica
Ott, 1987 had these comments on the findings, "Among
other cancer sites, there was a significant increase in
deaths due to other and unspecified malignant
neoplasms (12 observed v 4.6 expected). Review of the
death certificates... did not provide additional insights as
to the origin of the tumors. Nor did the internal analyses
identify any significant work area or dixoin-related
associations. Aside from noting that mortality for the
category tends to run somewhat higher at this plant
location [Midland]... we can offer no explanation for
Perhaps there is an explanation. Since the NIOSH found
a similar elevation in the 5172 workers from 12 different
companies that had been exposed to dioxins, this
suggests that the increased mortality is associated with
Bond, 1987 study is especially significant since the
study evaluated the mortality of approximately 37,682 male
employees that worked at Dow's Midland and Bay City sites
from 1940 to 1982. Although the study did not provide
specific mortality data for the Midland plant, it can be
assumed that the 29,420 (78%) Midland plant employees
endured the greatest amount of chemical exposure and
probably contributed the greatest number of deaths.
study also reported a statistically significant elevation in
mortality from these rare cancers in both the total cohort,
the hourly workforce and the salaried non-exempt workforce (Obs.
14 Exp. 6.6 SMR 213 (116-356).
is well recognized that the Dow's Midland site is heavily
contaminated with dioxins that were emitted from Dow's
hazardous waste incinerators. It is very probable that
dioxin exposure is the reason for the statistically
elevated mortality from these rare cancers.
the Bond, 1987 study, the additional number of deaths
from these rare cancers was 43.7 deaths spread over
almost 38,000 male employee spread over 42 years.
really do not know how many long term residents live on property
adjacent to the Tittabawassee Riverlet's assume 2000 and
let's also assume that the dioxin exposure is similar to
that experienced by the workers in the NIOSH study.
the 45 years that a certain resident lived on the river and
raised six daughters, a total of 88.9 cancers would be
expected in the 20 miles of river from Dow's plant to
the Saginaw River. According to the NIOSH study
results, an excessive number of cancer deaths would be
is very difficult to imagine that this resident would notice
an additional 13.5 deaths over roughly 45 years on
20 miles of river.
there are 5000 long term residents, the additional number of
cancer related deaths would be 33.5 additional deaths
over 45 years on the 20 miles of river.
Increased mortality from dioxin exposure does not reveal
itself as a cancer epidemic... dioxin takes its victims one
by one over many years... sometimes so slowly that only an
epidemiologist would notice.
a few others really notice... the persons that died prematurely and