Study of
DIOXIN&other
TOXIC POLLUTANTS
Midland, Michigan
U.S. EPA Region 5
April 1985
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DIOXIN
A generic term for a group of
75 related compounds known
as polychlorinated dibenzo-
p-dioxins. The most toxic
compound of this group is
2,3,7,8-tetrachloro-dibenzo-p-
dioxin (2378-TCDD). A num-
ber of the dioxins, including
2378-TCDD, are formed as
inadvertent byproducts dur-
ing the manufacture of or-
ganic chemicals, particularly
chlorinated phenols. Certain
combustion sources such as
municipal and industrial
waste incinerators and acci-
dental electrical transformer
fires have been shown to be
sources of 2378-TCDD and
other dioxins. The levels of
2378-TCDD from these
sources have been relatively
low compared to levels from
chlorinated phenols produc-
tion. 2378-TCDD is very per-
sistent in the environment.
It does not readily degrade
into less toxic chemicals.
Tests on laboratory animals
indicate 2378-TCDD is one of
the most toxic chemicals
made by man. Based on its
estimated carcinogenic po-
tency, cancer risks of individ-
uals who consume fish con-
taminated with high levels of
2378-TCDD could be signifi-
cant. Exposure to Dioxin
contaminated soils could
also significantly increase
cancer risk.
As part of its National Dioxin
Strategy, the U.S. EPA has
begun a national dioxin study
to determine the extent of
dioxin contamination in the
environment. The results of
that study are expected by
the end of 1985.
REPORT SUMMARY
At the State of Michigan's request, the U.S. Environ-
mental Protection Agency has been conducting
comprehensive environmental studies in the City of
Midland, inside the Dow Chemical Midland plant,
and at comparison sites across the Midwest. While
the primary focus of the studies was on possible
dioxin (2378-TCDD) contamination in the Midland
area, EPA also sampled for other toxic chemicals.
Results show that;
Current dioxin levels in surface soils away from
the Dow Chemical plant are well below one part
per billion (ppb). According to the Centers for
Disease Control, one ppb is the level at which
some action must be considered to prevent
human exposure to the dioxin-contaminated soil
in residential areas. Current levels of dioxin in the
Midland area, therefore, do not pose an unac-
ceptable public health risk.
Inside the Dow Chemical plant, EPA found con-
centrations as high as 36 ppb in surface soils.
(Dow Chemical reported concentrations as high
as 51 ppb.) Concentrations inside the plant are
generally in the lower range of levels found at
similar chemical manufacturing and disposal sites
in other parts of the country. EPA, the State of
Michigan, and Dow Chemical have entered into a
proposed consent order to provide interim cover-
ing of surface areas that have high concentra-
tions inside the plant. A public comment period
on the consent order began on March 20, 1985
and will last until April 17, 1985.
Concentrations of dioxin found in the City of
Midland away from the Dow plant are significantly
higher than the trace levels found in a few
samples taken in other cities. Most samples from
these comparison sites,and all samples from
natural areas,did not contain dioxin at detectable
levels.
Air emissions from the Dow Chemical plant are
the likely source of dioxin contamination in the
Midland area.
Current levels of toxic organic pollutants, other
than dioxins, in Midland soils are at levels found
elsewhere in the environment and do not pose an
unacceptable public health risk.
Because of high dioxin levels in fish taken from
the Tittabawassee River, a warning on eating fish
particularly bottom-feeding fish such as carp
and catfish should be continued.
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INTRODUCTION
This report presents a brief history of dioxin findings in the
Midland area, a description of EPA's soil study, the soil
study results, and conclusions from the Centers for
Disease Control (CDC) and EPA about health risks from
exposure to contaminated soils. In addition, data from
other locations, including cities that also have chemical
manufacturing plants and disposal sites, are compared to
data from Midland. Results and conclusions from fish
sampling in the Tittabawassee River are also presented.
The study in Midland has been incorporated into the
National Dioxin Strategy. The National Dioxin Strategy is
examining potential sources and risks of dioxin in the envi-
ronment. It is organized into seven tiers or categories
ranging from sites where dioxin was most likely to be found
(Tiers 1 and 2) to sites where contamination is not
suspected (Tier 7).
HISTORY OF DIOXIN FINDINGS
In June 1978, Dow Chemical advised the Michigan Depart-
ment of Public Health (MDPH) that it had found dioxin
(2378-TCDD) in fish caught from the Tittabawassee River.
The MDPH immediately issued an advisory against eating
fish from the river. That advisory is still in effect today.
Subsequently, the Michigan Department of Natural
Resources (MDNR), in cooperation with EPA, sampled fish
from the Tittabawassee River and confirmed Dow's
findings.
The agencies attempted to determine if Dow Chemical's
wastewater discharges, which flow into the Tittabawassee
River, contained the dioxin that was accumulating in the
fish.
However, at that time, regulatory agencies could not
detect dioxin at ultratrace levels in water because
analytical methods had not yet been developed that were
able to detect dioxin at very low levels.
In the fall of 1981, MDNR and EPA conducted a caged-fish
study in the Tittabawassee River to determine if Dow
Chemical was the source of the dioxin. Catfish were kept
in cages for 28 days both upstream and downstream of
Dow Chemical and directly in the plume of Dow's dis-
charge in the river. An experimental method of ultratrace
analysis for dioxin in water was also developed as part of
that study.
The preliminary results released in March 1983 demon-
strated that Dow Chemical's wastewater was the source
of dioxin. Subsequent analyses by Dow Chemical have
confirmed that finding.
In the spring of 1984, the State of Michigan, with EPA's
concurrence, issued a wastewater discharge permit and
an administrative order to Dow Chemical that limits the
discharge of 2378-TCDD. The order also requires the con-
struction of wastewater treatment systems as a first step
in reducing dioxin discharges.
In March 1983, the State of Michigan formally requested
EPA to conduct a comprehensive study of dioxins and
other toxic pollutants at Dow Chemical's Midland plant, in
the Tittabawassee River, and in the City of Midland. The
state and EPA planned the study in the spring of 1983. Soil
sampling was conducted in Midland, at Dow Chemical,
and at the comparison sites during 1983 and 1984. Dow
incinerator emissions, ambient air samples, Dow brine
system and wastewater samples, drinking water well
samples, and river sediment samples were also collected
in 1984.
SOIL STUDY
Study Objectives
The principal objective of the soil study was to determine
whether concentrations of dioxins and other toxic pollut-
ants in Midland surface soils could pose unacceptable
public health risks. The study was also conducted to deter-
mine the likely source or sources of ambient levels of diox-
ins in Midland; if levels found in Midland are comparable to
levels found in other industrial areas with combustion
sources and process operations different from those at
Dow Chemical; and whether levels found in Midland are
significantly different from background levels generally
found in the environment.
Conduct of the Study
The investigation of dioxin and other toxic pollutants in the
Midland area is one of the first and most comprehensive
studies conducted by EPA in which laboratory methods
capable of detecting 2378-TCDD at the low parts per
trillion (ppt) range were used.
(One ppt is 1,000 times less than one part per billion (ppb)
which is the level in residential soils at which CDC believes
some action to limit human exposure needs to be con-
sidered.)
Throughout this study, elaborate quality assurance controls
were used to ensure that accurate data were produced.
Field work was thoroughly documented. Duplicate soil
samples were obtained at certain locations. Clean, dis-
posable sampling equipment was used for each sample.
Each sample was coded with a unique identification
number. The samples were thoroughly blended in a labora-
tory before extraction and analysis.
All samples were then analyzed on a blind basis, that is,
EPA laboratories at Bay St. Louis, Mississippi, and
Research Triangle Park, North Carolina, did not know
where the samples had been taken or the identity of the
samples they were analyzing. Control and blank samples
were also submitted to the laboratories on a random, blind
basis. In addition, EPA provided split samples to Dow
Chemical on a blind basis for comparative analyses.
Dow's analyses confirmed EPA's results.
EPA believes that the data obtained accurately reflect sur-
face soil conditions in Midland, at Dow Chemical, and at
the comparison sites. This set of high quality data is suffi-
cient to evaluate health risks to Midland residents from
exposure to current levels of 2378-TCDD and other pollut-
ants in Midland soils.
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NATURAL AREAS IN
MINNESOTA
This site consists of the following four areas
managed by the Minnesota Department of
Natural Resources as scientific and natur-
al areas:
Kettle River Scientific and Natural Area
Pembina Trail Scientific and Natural
Area
Itasca Wilderness
Bluestem Prairie Scientific and Natural
Area
Scientific and Natural Areas are estab-
lished by the State of Minnesota to protect
and perpetuate natural features that
possess exceptional scientific or educa-
tional value. The Kettle River area is a
760-acre tract typical of the woodlands of
eastern Minnesota. Pembina Trail is one
of the largest remaining tracts (1,660
acres) of native prairie in Minnesota.
Itasca Wilderness is-a 2,000-acre tract of
pine-dominated forest that has never been
logged. Bluestem Prairie is another prairie
that has not been affected by nearby pol-
lution or combustion sources. These areas
are considered Tier 7 sites, or background
sites, for EPA's National Dioxin Strategy.
FIGURE 1
MAP OF EPA REGION 5
SHOWING LOCATIONS
OF SOIL STUDY SITES
MIDLAND, MICHIGAN
The major industries in the City of Midland
(population 37,250) are the Midland plant
of the Michigan Division of Dow Chemical
Company and the Dow-Corning Silicone
Products plant. Dow Chemical's Midland
plant falls within Tiers 1, 2, 3, and 4 or
EPA's National Dioxin Strategy in that
2,4,5-trichlorophenol (2,4,5-TCP) was pro-
duced (Tier 1); 2,4,5-TCP was used to
make pesticide products (Tier 2); 2,4,5-TCP
and derivatives were formulated into
pesticidal products (Tier 3); and the plant
is also a combustion source (Tier 4).
Pembina Trail
Itasca Wilderness
A 0
\/ Bluestem Prairie
Kettle River
MINNESOTA
WISCONSIN
Midland Site
MICHIGAN
Henry Site
OHIO
Middletown Site
INDIANA
ILLINOIS
HENRY, ILLINOIS
The principal industry near Henry, Illinois,
is a polyvinyl chloride manufacturing plant
operated by the B.F. Goodrich Chemical
Company. The plant has numerous pro-
cess vents and some combustion sources.
There are no Tier 1 or Tier 2 sites as
defined by EPA's National Dioxin Strategy
in the Henry, Illinois area. Henry has a
population of about 2,700.
MIDDLETOWN, OHIO
The City of Middletown (population 43,700)
is in southwestern Ohio. The principal
industries are the ARMCO, Inc. Middle-
town Works; Sorg Paper Company; and
Crystal Tissue Company. The ARMCO,
Inc. Middletown Works is a fully integrated
steel plant that has cokemaking, iron-
making, and steelmaking operations. Sorg
Paper manufactures fine paper from pur-
chased pulp, recycled paper, and paper
wastes. Crystal Tissue manufactures fine
tissue and wrapping papers from virgin
pulp. There are no Tier 1 or Tier 2 facilities
as defined by EPA's National Dioxin Strat-
egy in the Middletown, Ohio, area.
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Soil Study Results
The study results for 2378-TCDD for each site are sum-
marized in Table 1. The Dow Chemical and City of Midland
data are highlighted in the centerfold of this summary
report.
Figure 2 compares the ranges of dioxin levels found in sur-
face soils at each of the comparison sites with levels found
in Midland. The data show that levels of dioxin in Midland
away from the Dow plant are well below the 1 ppb level of
concern established by CDC for residential soils. One sam-
ple obtained near the east fence line of the Dow plant had
a dioxin concentration of 2.03 ppb. Supplemental sampling
conducted by Dow Chemical around the site showed the
2.03 ppb concentration to be isolated to a small area. Dow
Chemical has extended its fencing around that site to pre-
vent public access.
The next highest sample obtained near the perimeter of
the Dow plant contained less than 0.55 ppb of dioxin. Fre-
quent and prolonged exposure of the public to soils around
the perimeter of the Dow plant is not likely.
Figure 2 also shows that, while levels of dioxin found in
Midland are well below CDC's level of concern for residen-
tial areas, those levels are higher than found around other
industrial sites and in natural areas.
Figures 3, 4 and 5 present the dioxin data for Midland
public use and residential areas, the perimeter of the Dow
plant, and inside the Dow plant. The data in Figure 3 show
that most values of 2378-TCDD in Midland public use and
residential areas are at or less than 0.10 ppb. All values
were less than 0.30 ppb.
Four out of the five highest values in the city were found at
residential downspouts, indicating that airborne emissions
from Dow Chemical are the likely sources of dioxin. Down-
spouts can be good indicators of atmospheric contamina-
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FIGURE 2
COMPARISON OF
MIDLAND SOIL DATA
TO OTHER SITES
Geometric Mean
Arithmetic Mean
CDC LEVEL OF CONCERN
FOR RESIDENTIAL SOILS
TJ TJ ģ O " S
c c o Ž rr
-------
2378-TCDD
SURFACE SOIL CONCENTRATIONS
MIDLAND, Ml
o
o
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o
p
4.6
DOW
CHEMICAL ^
COMPANY
INCINERATOR
LAGOOIN
CONSUMEI
COOLING I
-------
LEGEND
2378 - TCDD
(PARTS PER BILLION)
1+
0.5-1.0
0.1 -0.5
0.05-0.10
] 0.001 - 0.05
O OPEN AREA SAMPLE
DOWNSPOUT SAMPLE
o
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On
(36.0)
DOW
CORNING
O
FJS POWER CO.
'ONDS
-------
9
8
7
6
5
4
3
2
1
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FIGURE 3
PUBLIC USE AND
RESIDENTIAL AREAS
MIDLAND, Ml
y
2378-TCDD (ppb) in
SURFACE SOILS
M
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.05 .10 .15 .20
Concentration (Parts Per Billion)
IX
N
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(0
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FIGURE 4
PERIMETER DOW CHEMICAL
MIDLAND PLANT
2378-TCDD (ppb) in
SURFACE SOILS
L
0.5 1.2 1.5
Concentration (Parts Per Billion)
2.0
a
E
E
a
Z
FIGURE 5
DOW CHEMICAL
MIDLAND PLANT
2378-TCDD (ppb) in
SURFACE SOILS
I
_L
_L
1.0 3.0 3.5 4.0
Concentration (Parts Per Billion)
4.5 35.5
36.0
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tion because airborne particles tend to collect on exposed
surfaces such as building roofs. These particles are
washed from the roofs by rain and deposited in soils
around the downspouts.
Figure 4 shows that although one value of 2.03 ppb was
found on the perimeter of the Dow plant, the next highest
value is less than 0.50 ppb. Data presented in Figure 5 indi-
cate that most values found inside the Dow Chemical plant
have less than 0.50 ppb of 2378-TCDD. A few sampling
locations inside the Dow plant had concentrations in the 3
to 5 ppb range and one location had a dioxin concentration
of 36 ppb. Supplemental sampling by Dow Chemical indi-
cates that most of the Dow plant had dioxin concentrations
less than 1 ppb, although one sample had a value of 51 ppb.
CDC has stated that, based on experience at similar
facilities, it is doubtful whether significant dioxin exposure
to workers would occur at the plant unless the soil was
disturbed because of construction or similar activities.
EPA, the State of Michigan, and Dow Chemical have
entered into a proposed consent order by which Dow
Chemical will provide interim covering of the two identified
high concentration areas with asphalt to minimize expo-
sure to plant workers and prevent migration of dioxin
offsite.
Consideration of Health Risks
The data from this study were reviewed by CDC to deter-
mine whether levels of dioxin and other pollutants in
Midland soils might pose unacceptable health risks to
Midland residents.
CDC concluded that levels of 2378-TCDD in Midland soils
are well below the 1 ppb level at which some action to limit
human exposure to residential soils needs to be consid-
ered; and, that levels found in residential soils, including
downspout areas, do not represent a significant health risk
to either the persons living there or the public at large.
The levels of other dioxins, furans, and other toxic
chemicals, which are all less toxic than 2378-TCDD, do not
represent an unacceptable public health risk. CDC also
concluded that levels of other toxic chemicals are within
the range of levels found generally in the environment.
CDC also states that its assessment is based upon current
environmental data, and no comment can be made about
past environmental levels and potential risks.
EPA's Chlorinated Dioxins Work Group at EPA Headquart-
ers in Washington, D.C., also evaluated the data and came
to the same conclusions as CDC.
Comparison with Other Dioxin Sites
Figure 6 compares data obtained at Dow Chemical and in
Midland with data from other chemical manufacturing
sites and disposal sites where dioxin has been found.
These are Tier 1 and Tier 2 sites for EPA's National Dioxin
Strategy. These data show that the levels of 2378-TCDD
found at Dow Chemical are, for the most part, in the range
of, or lower than, levels found at other Tier 1 and Tier 2
sites.
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FIGURE 6
MAXIMUM 2378-TCDD AT SELECTED
TIER 1 AND TIER 2 SITES
Onsite/Offsite Concentrations in
Surface Soils(in ppb)
LEGEND
>1000= Greater than
1000 ppb
NA = Not Available
ND = Not Detected at
0.35 ppb or less
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-------
FISH STUDY
During the summer of 1983, MDNR collected fish from the
Tittabawassee River and several other Michigan rivers for
dioxin analyses.
For most rivers, samples of bottom-feeding fish such as
carp and catfish were collected along with samples of
game fish including walleye and bass. The fish were
analyzed by U.S. EPA's Environmental Research Labora-
tory in Duluth, Minnesota. The results for the Tittaba-
wassee River, which are summarized in Table 2, were
originally released to the public by MDNR in October 1984:
Whole fish composite samples of carp from 11 other
Michigan rivers had levels of 2378-TCDD ranging from
none detected to 8.6 ppt.
Figure 7 presents data obtained for the 25 carp fillets and
5 walleye fillets from the Tittabawassee River. The concen-
trations of 2378-TCDD in carp are much higher than con-
centrations in walleye. As shown in Table 2, the average
carp fillet concentration is about 50 ppt, while the average
for walleye is about 4 ppt.
The Food and Drug Administration recommends that fish
with more than 50 ppt of 2378-TCDD not be eaten and fish
in the range of 25 to 50 ppt be consumed only on a limited
basis. Based upon the data obtained from this study, both
CDC and EPA recommend that the MDPH warning on con-
sumption of fish from the Tittabawassee River be main-
tained.
As a result of a March 1984 consent decree with EPA, Dow
Chemical has agreed to analyze dioxin levels in fish from
the Tittabawassee River every 2 years beginning in 1985
and lasting until 1991. This program has been approved by
EPA and MDNR and will be monitored by the agencies.
The purpose of the program is to determine whether
wastewater treatment systems now being installed by Dow
Chemical to control dioxin are having a beneficial impact
on dioxin levels in Tittabawassee River fish.
8
FIGURE 7
1983 FISH COLLECTION
IN TITTABAWASSE RIVER
NEAR MIDLAND, Ml
2378-TCDD (ppt)
(/>
4)
a
E
54
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FISH
TABLE 2
STUDY RESULTS
2378-TCDD
(Results in Parts Per Trillion)
Tittabawassee River Fish
(August-September 1983)
Number of
Measurements
Range
Mean
Carp whole fish composite (5 fish)
1
190 ppt
Carp individual skinless fillets
25
12-530 ppt
50 ppt
Catfish skinless fillet composite (5 fish)
1
75 ppt
Smallmouth Bass skin-on fillet
composite (5 fish)
1
5.1 ppt
Walleye individual skin-on fillets
5
2.8-5.1 ppt
3.9 ppt
Note: A composite fish sample is made up of a number of individual fish blended together prior to analyses.
Bottom-feeding fish were sampled because they are more likely to pick up contamination in river sediment.
ACRONYMS
EPA U.S. Environmental Protection Agency
CDC Centers for Disease Control
MDNR Michigan Department of Natural Resources
MDPH Michigan Department of Public Health
PPB Parts Per Billion
PPT Parts Per Trillion
2378-TCDD dioxin or 2,3,7,8 tetrachlorodibenzo-p-dioxin
GLOSSARY
Ambient Air Air outside the property limits of industrial or
other types of facilities.
Administrative Order An order issued by an EPA adminis-
trator in accordance with congressional authorization that re-
quires a party to correct environmental problems.
Background Levels Concentrations of chemicals that are
found in the environment away from manmade pollution
sources.
Carcinogen A substance or agent that produces or incites
cancer.
National Dioxin Strategy In December 1983, EPA
announced a National Dioxin Strategy to determine the extent
of dioxin contamination throughout the country. The strategy
provides a framework under which the Agency will:
Study the nature of dioxin contamination throughout the
United States and the risks to people and the environment
Clean up dioxin-contaminated sites that threaten public health
Find ways to prevent future contamination
Find ways to destroy or dispose of existing dioxin.
To carry out its dioxin strategy, EPA established seven cate-
gories or tiers of sites for investigation and study. These sites
range from those that are most probably contaminated (Tiers 1
and 2) to those where there is no expectation of contamination
(Tier 7). EPA believes more than 80 percent of the dioxin in the
environment is associated with the Tier 1 and 2 sites. The other
tiers are being evaluated in EPA's National Dioxin Study, which
was started in the summer of 1984, and is scheduled for com-
pletion by the end of 1985.
Parts Per Billion, Trillion One part per billion, the level at
which CDC says action must be considered to prevent human
exposure to 2378-TCDD in residential soils, is equivalent to one
inch in about 16,000 miles. A part per trillion is one thousand
times less than one part per billion.
Split Samples To ensure the accuracy of laboratory
analyses, samples are often divided and sent to different labo-
ratories for comparative analyses.
Toxic Chemical Any of a number of chemicals considered
by EPA for special regulatory attention because of the adverse
impacts these chemicals can have on man, animal life, or the
environment in general. Many are lethal in single high doses or
cause long term illness if administered at low doses over longer
periods of time.
AVAILABLE INFORMATION
For more information about EPA's dioxin studies in the Midland area, please review the information repositories at
the following locations:
Grace A. Dow Memorial Public Library
1710 W. St. Andrews Drive
Midland, Ml 48640
(517)835-7151
Dr. Winifred Oyen, Director
Midland Health Department
125 W. Main Street
Midland, Ml 48640
(517) 832-6655
Ingersoll Township Hall
c/o Kurt Shaffner, Supervisor
4400 Brooks Road
Midland, Ml 48640
(517) 835-5289
For additional information, please contact:
Vanessa Musgrave
U.S. EPA Community Relations Coordinator
230 South Dearborn Street
Chicago, IL 60604
(312) 886-4359
1-800-621-8431 (toll free, 8:30 a.m.-4:30 p.m., Central Time)
Gary A. Amendola
U.S. EPA Project Manager
Michigan Dioxin Studies
U.S. EPA Eastern District Office
25089 Center Ridge Road
Westlake, OH 44145
(216) 835-5200
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