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Dow Newsletter November 2004 |
Dow Statements |
MDEQ Analysis of Dow statements |
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Page 1, Column 1, Paragraph 2 |
This analytical work is important because dioxins and
furans are perhaps the most frequently studied compounds, yet the
findings about their toxicity – especially in humans – are inconclusive.
Despite the claims of some, the overwhelming weight of scientific
evidence does not support the fact that dioxin/furan exposure at low
levels is cause for serious concern |
This is an overly generalized and ambiguous statement.
The Environmental Protection Agency, International Agency for Research
on Cancer (IARC), U.S. Department of Health and Human Services, and
other government organizations recognize 2,3,7,8-TCDD as a known human
carcinogen and dioxin mixtures (toxic equivalence or TEQ) as suspected
or probable human carcinogen. |
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Page 1, Columns 2 and 3 |
Topics: Dow Releases Results of
Current Worker Study Blood Levels Elevated, Still Below CDC Level for
Cancer Concern ...No Indication of Health Effects...People More
Resistant |
It is difficult to review this section because Dow would not provide
the actual study results or even a copy of the Powerpoint presentation
given to staff of the Departments of Community Health (DCH) and
Environmental Quality on November 3, 2004. DCH staff requested this
information on November 4, 2004. Dr. Michael Carson of Dow declined to
provide the requested information |
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Page 1, Column 2, Paragraph 3: |
Heading: No Indication of Health Effects
Text: “Given these new study findings, we are more
confident than ever about our health conclusions that, other than
chloracne among highly exposed workers, we find little indication
of any health effect related to dioxin exposure in our chlorophenol
workers,” said Dow Medical Director, Dr. Mike Carson... |
The heading of this section states “No Indication of
Health Effects” and the text indicates that Dow finds “little indication
of any health effect related to dioxin exposure in our chlorophenol
workers |
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Page 1, Columns 2 and 3, Paragraph 6 |
No worker in the Dow study had these high
levels of dioto 176 ppt TCDD.xin in their blood. The range for Dow
employees was 2 |
In 2004, this is the range Dow reports. Dioxin is eliminated from
the body with a half life of approximately seven years. If the Dow
reported levels are corrected for elimination via half life, this range
would be much higher. It is not accurate to compare the 2004 Dow data to
the levels reported by the Centers for Disease Control which are the
estimated highest serum levels at the time of last exposure. |
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Page 1, Columns 3, Paragraph 2 |
People More Resistant:
The CDC also states: “Although dioxin is extremely toxic in some
animals, humans appear to be more resistant to its toxicologic effects
than most animals in which it has been tested. The primary clinical
health effects that have been observed in humans exposed to high levels
of dioxin through occupational or accidental exposures have been
chloracne and transient mild hepatotoxicity. Various types of cancer and
non-cancer health effects also have been associated with exposure to
dioxin in some studies. However, study results have been inconsistent in
demonstrating these effects.” |
The section, “People More Resistant,” is misleading.
The statement cited is not proven for all adverse effects that have been
associated with dioxin exposure. For example, for effects that have been
clearly associated with dioxin exposure, such as chloracne and the
induction of liver enzymes, humans and animals respond at similar body
burdens. For some effects, humans are more sensitive than certain other
mammalian species (e.g., chloracne in mice, cancer in hamsters,
decreased testosterone in rats). |
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Page 2, Column1, Paragraph 4 |
To date, the studies show that Dow workers with high
levels of dioxin exposure do have an increased risk of chloracne, a skin
condition known to be caused by such exposure. However, other than
chloracne, no other increased risk of disease, including cancer, was
found related to dioxin exposures. These results are consistent with
recent observations published by the U.S. Agency for Toxic Substances
and Disease Registry and the national Centers for Disease Control. |
The more comprehensive studies by National Institute
for Occupational Safety and Health (NIOSH) and IARC do show increased
risk of disease (cancer, ischemic heart disease). These results were
reaffirmed in 2004. Dow should cite the study to which they referred. |
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Page 2, Column 2, Paragraph 4 |
Bioavailability Study. Dow also is
conducting a pilot bioavailability study. Bioavailability refers to the
ability of the human body to absorb any compound. This study will help
find out how much dioxin can be absorbed into the body if it is attached
to soil. Since dioxins firmly bond to soil particles and are not readily
absorbed into the bloodstream, it is important to understand this
process. ... What’s more, a German study found the level to be as low as
15 percent. ... |
The bioavailability study design has not been approved by the DEQ.
An independent peer review by Toxicology Excellence in Risk Assessment (TERA)
indicates that there are major problems with the study design. In
addition, it has not been demonstrated at this location that dioxins are
“firmly bound” to soil and are not readily absorbed into the blood. In
fact, based on Dow’s wild game study and Michigan State University’s (MSU)
ecological risk studies, dioxins in the Tittabawassee River floodplain
appear to be very bioavailable. The German study referred to in
this discussion may not be relevant as bioavailability varies based, in
part, on soil type and contamination. |
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Page 3, Columns 2 and 3 |
Studies Will Clarify Models
Several studies help in our understanding of the validity of the models
being used to assess potential risk of exposure to dioxins and furans.
Dow’s recent study of the levels of dioxins in wild game such as deer,
turkey, and squirrels from the flood plain area
 |
Dow’s graphs and comparisons are flat out
misrepresentations of the actual facts, data, and model for the
DEQ’s screening level terrestrial ecological risk assessment (ERA)
evaluation. The DEQ made no estimates of the level of
contamination expected to be present in squirrels and turkeys from the
Tittabawassee River floodplain. It would have been, and is,
inappropriate to use the DEQ’s screening level terrestrial ERA to
attempt to make such calculations. The DEQ was, in fact, surprised by
the high levels of dioxins found in the portions of squirrels, turkeys,
and deer consumed by humans. Higher levels of contamination are expected
to be present in portions of animals that are consumed by prey species.
The recently released MSU ecological data support the DEQ’s conclusion
that ecological risk from dioxins is present in the Tittabawassee River
floodplain. Levels of dioxin in small ground dwelling mammals is on the
order of 100 times higher than the squirrel data reported by Dow. |
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Page 4, Column 3, Paragraph 1 |
“This CDC data is important for understanding the
connection between age and dioxin levels in the blood,” said Dow
Toxicologist Bob Budinsky. “Since everyone has dioxin in their blood,
and dioxin breaks down very slowly, the study suggests it is most
appropriate to assign guidelines by age.” |
The “guidelines” referred to in this paragraph are
actually concentration ranges. Exposure to these concentration ranges
may result in adverse health effects. Some studies in humans have
shown adverse health effects associated with background levels of
dioxin. |
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Page 5, Columns 1 and 2 |
Dow is working in cooperation with Saginaw
area officials to help improve two Tittabawassee River parks and at the
same time take steps to minimize potential exposure to dioxins and
furans. Dow and parks officials recently received permit approval for
improvement projects at Imerman and Freeland Festival parks. The work is
part of the corrective action process by Dow and was proposed as an
interim response activity (IRA). |
The Interim Response Activities (IRAs) referred to in this section
have not been approved by the DEQ. This section does not discuss
critical components of the IRAs, which include advisory signage to
reduce exposure to contaminated soil and fish.
Please note that “permit approval” likely refers to floodplain
permits, not Part 111 approval of the IRAs for corrective action
purposes as is implied by the wording.
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Page 5, Column 3, Paragraph 1 |
Other key findings of the study are as follows:
• Some tradesmen who had plant-wide responsibilities, such as
pipefitters and mechanics, also had dioxin levels above non-chlorophenol
workers.
• Workers with past chloracne had higher blood dioxin levels – five
times higher on average than other workers employed in the chlorophenol
departments.
• Dioxin exposure estimates used in the previous studies of Dow workers
accurately predicted actual, measured dioxin levels. |
Based on Dow’s November 3, 2004 presentation to DCH and
DEQ staff, chloracne did not predict serum dioxin levels (i.e., some
workers with high dioxin levels did not exhibit chloracne).
Dow’s exposure estimates did not predict actual measured dioxin
levels as stated in this paragraph. Instead, they predicted relative
levels of exposure.
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Page 5, Column 3, Paragraph 7 |
Results of the study were presented in October at the
International Symposium on Epidemiology and Occupational Health in
Melbourne, Australia. Dow also met with local health department
officials, and has briefed the Michigan Department of Community Health
and the Michigan Department of Environmental Quality on the research. |
Although Dow briefed DCH and DEQ staff on the worker
study, Dow declined to provide the actual study results when
requested to do so on November 4, 2004. |
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Page 6, Column 2, Paragraph 2 |
A new cancer study on laboratory animals,
recently completed by the U.S. National Toxicology Program, shows that
the furan congener 4-PCDF (which makes up about 50 percent of the TEQ in
the Tittabawassee River area) is much less potent in laboratory animals
than originally thought. |
A publication of the study cited by Dow supports the TEQ approach,
which is an order of magnitude estimate of overall toxic potency (not
just cancer). Also, it should be clarified that toxic equivalency
factors (TEFs) are developed based on specific toxicity studies of the
individual compounds. The TEF for 2,3,4,7,8-PeCDF (not 2,4,7,8-PCDF)
estimated from this study were 0.16 to 0.34 for four tumor types, which
are within half an order of magnitude of the current TEF of 0.5. The
study cited here also verified that the cancer incidence from a mixture
of three dioxin-like compounds was adequately predicted by the TEF
approach and did not over-predict toxicity as implied by Dow. |
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Page 7, Column 1, Paragraphs 3 and 4 |
This data will help clarify whether there
is a link between dioxins in soil/house dust and in human blood. If
dioxin levels are not elevated in residents’ blood, it would indicate
there is no increased health risk for area residents. If levels are
elevated, additional health studies would be appropriate, to determine
if there is a correlation with dioxin exposure. The results also will
provide another point of tangible data on which to base decisions about
corrective action in Midland and the Tittabawassee River area. Go to
http://umdioxin.org for additional information. |
The University of Michigan Dioxin Exposure Study (UMDES) as designed
will not be able to conclusively determine the exposure of the specific
population of greatest concern, residents who live on properties that
frequently flood. Also, as noted above, even if these residents have
dioxin levels within the background range, it does not mean that there
will be no increased health risk.
The DEQ will not be able to use the UMDES for corrective action purposes
as described here. In addition, it is not appropriate to wait until
the study is completed in 2007 to begin to take actions to reduce
exposure.
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