UNITED STATES ENVIRONMENTAL PROTECTION AGENCY
SUBJECT:
FROM:
TO:
08FEB1979
Status Report* 8EHQ-1173-0209
(Supplement)
Frank D. Kover
Assessment Division, OTE/OTS
Joseph J. Merenda, Director
Assessment Division, OTE/OTS
Approved
•Revision
Needed
Submls s ion Description
The submission was made as a followup to Dow Chemical
Cc-mpany's two earlier submissions on the detection of
chtSrjnated dioxins and other chlorinated organics in
various environmenta1! samples. In a press release (attached) ,
Dow concluded that "its research ... has verified the follow-
ing sources for chlorinated dioxins: refuse incinerators,
fossil-fueled powerhouses, gasoline and diesel powered
automobiles and trucks, fireplaces, charcoal grills and
cigarettes." On the basis of this work, Dow concluded that
"dioxins occur everywhere as a result of normal combustion
processes." The submission consists of the press release
and related material, a report presenting Dow's data and
conclusions, and several appendices describing sampling and
analytical methodologies.
Ev^ckg round
T":.e polychlorinated dibenzo-p-dioxins (PCDDs) are a series
of tricyclic aromatic compounds which exhibit similar
chemical and physical properties. The basic structure of
PCDDs (as shown below) has eight possible points of chlorine
substitution. From the monochloro to the octachloro deriva-
tives, a total of 75 different positional isomers is possible.
•0-
P,
*NOi'E: This status report is the result of a preliminary
staff evaluation of information submitted to EPA. Statements
made herein are not to be regarded as expressing final
Agency policy or intent with respect to this particular
chemical. Any review of the status report should take into
r--sideration the fact that it may be based on incomplete
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The most extensively studied isomer of the PCDDs is 2,3,7,8-
tetrachlorodibenzo-p-dioxin (2,3,7,8-TCDD), one of the most
potent toxicants presently known. The toxic effects induced
by other TCDD isomefs are less well characterized; however,
they appear to exhibit a lesser degree of toxicity (both
quantitatively and qualitatively) than 2,3,7,8-TCDD. For
these reasons, the PCDD isomer attracting the greatest
amount of Agency interest and activity is the 2,3,7,8-TCDD.
Submission Evaluation (An overall evaluation of the
submitted information will be presented in this
section of the status report; a detailed technical
evaluation of the submission can be found in the
attached appendix.)
The information contained in the present submission was
received as a followup to the Dow Chemical Company's earlier
submissions of June 28, 1978 (8EHQ-0678-0209) and October
11, 1978 (8EHQ-1078-0209 [Followup]) which concerned the
presence of chlorinated dioxins in Tittabawassee River fish
collected near Dow1s Midland, MI chemical plant. A detailed
description and evaluation of the June, 1978 submission can
be found in the status report prepared for that submission.
The following listing summarizes the most important points
from that initial Dow submission.
a) Tetrachloro dibenzo-p-dioxiris (TCDDs, isomers not
identified) appear to be widespread contaminants of the
Tittabawassee and Saginaw Rivers (and possibly Saginaw Bay)
downstream from Midland. Octachloro dibenzo-p-dioxin (OCDD)
also appears to be widely distributed downstream of Dow.
TCDD was no.t detected in 3 fish taken upstream of the Dow
Midland facility, although OCDD was apparently detected in
one of these fish.
b) Five of six caged rainbow trout held in a mixture
of Dow1s tertiary waste treatment effluent under flowing
conditions for 7 days accumulated traces of TCDD (ppt).
c) Caged rainbow trout held in flowing waters appro-
ximately six miles downstream from Dow's plant accumulated
detectable amounts (ppt) of TCDD (whole fish analysis) after
30 days of exposure. This indicates downstream movement of
TCDD.
Based on the above, it appeared that Dow's discharge repre-
sented the major, if not the only, source of the chlorinated
dioxin contamination found in the Tittabawassee and Saginaw
Rivers and Saginaw Bay in Michigan.
The latest submission represents the output of a Task Force
established by Dow's Michigan Division "to identify the
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potential sources of the chlorinated dioxins" found in the
Tittabawassee River. This report advances as "strongly
supported" a number of conclusions that, on careful evalua-
tion, have no documented support in the information submitted
by Dow. A detailed evaluation of Dow1 s report is provided
in the attached appendix; the main points resulting from the
Agency's evaluation have been condensed as follows:
a) No information, other than purely circumstantial
evidence, has been submitted by Dow to support the premise
that polychlorinated dibenzo-p-dioxins (PCDDs) and especially
the TCDDs are typical by-products of combustion. Other
investigators have demonstrated under laboratory conditions
that PCDDs can be formed during the pyrolysis of polychloro-
phenates or polychlorophenoxy-containing materials. However,
there is no experimental evidence (either submitted by Dow
or present in the literature) indicating that combustion in
the absence of PCDD precursors normally results in PCDD
synthesis.
b) Much of the analytical work reported by Dow in this
submission used methods that have "not always been validated
and not yet corroborated by other scientists." Because of
this, little or no analytical significance can be derived
from the results reported by Dow. In order to derive signifi-
cant and valid analytical meaning and/or conclusions from
the results of part per billion (ppb) and part per trillion
(ppt) analysis for PCDDs, the results must be accompanied by
(1) appropriate quality control results and (2) a complete
description of the criteria used to identify and confirm the
presence of PCDD residues.
c) M?ay of the PCDD residue values relied on by Dow
when formulating its conclusions as to the "ubiquity" of
PCDDs were identical or approximately equal to the analytical
method's level of detection. Such numbers have uncertain
analytical significance especially in situations when non-
validated analytical methods are employed.
d) Dow claims (p.21 of its report) that the results of
its analysis of soil and dust samples "strongly support the
conclusion that chlorinated dioxins are produced in incinera-
tors and fossil fueled powerhouses as a consequence of
combustion." In point of fact, the results presented by Dow
offer no scientific documentation (other than weakly circum-
stantial evidence) relating its observations on PCDD contam-
ination of soil and dust to the synthesis of PCDDs as a by-
product of incineration or power generation. There is some
circumstantial evidence that the hexachloro dibenzo-p-
dioxins (HxCDDs), heptachloro dibenzo-p-dioxins (HpCDDs),
and octachlbro dibenzo-p-dioxins (OCDDs) identified in the soil
samples from the urban and the metropolitan areas may be
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associated with the operation of a powerplant and an incinerator,
respectively. This, however, does not demonstrate that the
presence of these substances results from their synthesis as
a normal combustion by-product. EPA's evaluation of these
data indicates that the following conclusions, contrasting
Dow's claims, can be supported:
(1) Midland, MI, and especially the area around
the Dow plant, exhibits the greatest evidence
for gross PCDD contamination among the various
locations sampled. This is true both in
terms of the proportion of samples in which
PCDDs were detected and the degree of contamina-
tion evident in individual samples. In the
latter case, the levels of PCDDs found in
Midland are 2-4 orders of magnitude greater
than those reported at other locations. Th -.
fact that much higher levels of PCDDs were
found in soil and dust around the Dow cheiuic-al
plant as compared to urban, metropolitan, and
rural areas suggests that polychlorophenol
production or some other activity at the Dow
plant may be the source of the observed PCDD
contamination.
(2) To the extent that TCDDs, especially 2,3,7,8-
TCDD, are the PCDDs of greatest Agency concern,
the levels of TCDDs identified in Midland soil
and dust samples indicate that this area
represents a definite TCDD "hot spot." In
comparison, there are very few instances where
TCDDs were reported at other sites.
e) In part V of its report, Dow cites several European
authors who have reported the presence of PCDDs in fly ash
from municipal incinerators and in fly ash from an industrial
heating facility. Dow notes (p.22 of its report) that one
of the authors postulates that the PCDDs are formed as a
result of the thermal condensation of chlorophenols, although
mention is made in the article that a thermal synthesis
reaction involving inorganic chloride and organic material
"was considered to be entirely possible." Dow, however,
fails to discuss several other studies which indicate that
the pattern of PCDD isomers identified in fly ash (from
incinerators and heating facilities) was almost identical to
that found when a mixture of polychlorophenates was pyrolyzed
under controlled conditions. One of these papers goes on to
state that available evidence indicates that commercial
chlorophenols cannot be excluded as the precursor to PCDDs
in fly ash. The information submitted by Dow appears to
offer some degree of support for this statement. In general,
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fly ash from DOW'S- chemical waste incinerators show higher
Levels of PCDDs than does fly ash from its fossil fueled.
powerhouse. The difference may be related to the nature of
the material being burned in each operation. One possible
explanation is that the chemical wastes being burned in Dow's
incinerators already contain PCDDs or PCDD precursors (poly-
chloropherioxy material)(i.e., wastes from Dow's chlorophenol
production processes) and tha.t these substances are the
sources of the observed PCDDs.
f) Dow claims (on p.30 of its report) that "wipe
testing and air monitoring data are strong evidence that
(Dow) manufacturing plants do not emit levels of chlorinated
dioxins sufficient to explain the finding of these compounds
in the soil samples reported earlier." No scientific basis
for this conclusion is provided in the data presented by
Dow.
g) Dow reports (pp.33-35) trace quantities of PCDDs in
scrapings taken from the inside of car and diesel truck
mufflers. Does this necessarily mean, as Dow advances, that
PCDDs are formed during combustion in the engine? If the
car or truck was driven primarily in an industrial area or
near sources that might be considered contaminated with
PCDDs or PCDD precursors, airborne particulates containing
these substances could be drawn into the air intake of the
engine. Any PCDDs not decomposed in passage through the
engine might then be deposited in the muffler. The state-
ment (p.35) that PCDDs "are in particulate emissions from
internal combustion engines" cannot be supported because
vehicles' exhaust gases were not analyzed. The only conclu-
sions that can be supported by the observations presented in
this section are that (1) PCDDs have been identified in some
muffler scrapings, however, (2) the source of the PCDDs is
unknown.
h) Dow claims (pp.35-36) that soot collected from 2
fireplaces contains PCDDs; however, Dow offers no documenta-
tion of its claim that none of the wood burned in the fire-
place "had been treated'with any wood preservatives."
Without such evidence, these results can not support Dow's
thesis concerning the synthesis of PCDDs as a normal combus-
tion by-product.
i) The geographic locations of the homes Where fireplace
soot and home electrostatic precipitator particulates were
sampled may be important. This is of interest because the
dust collected in the electrostatic precipitator (electronic
air cleaner) had a higher concentration of PCDDs than the
soot samples from the fireplaces (acknowledged sources of
typical combustion by-products). A home electrostatic
precipitator functions to a certain extent as a "high volume
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air sampler." In the case cited by Pow, the electrostatic
precipitator was operated, over a period of 6 spring and
summer months. Thus, the precipitator particulates analyzed
by Dow represent airborne material collected over a 6 month
period which does not coincide with the months generally
associated with heavy space heating-related combustion or
home fireplace usage. Therefore, the PCDD values for the
home electrostatic precipitator-collected particulates may,
to a certain extent, represent the results of incidental ambient
air "sampling" conducted at the site of the house.
j) Dow claims to have verified charcoal grills and
cigarettes as sources of PCDDs. No evidence is presented to
indicate that charcoal grills per se produce PCDDs, although
an attempt is made to show that steaks cooked on charcoal
grills contain newly synthesized PCDDs. The reported PCDD
residue values, however, are identical or approximately equal
to the analytical method's level of detection such that the
reported values have limited analytical significance. In
its cigarette assays, Dow reports finding picogram (10-12g)
concentrations of PCDDs per cigarette (in trapped cigarette
smoke particulates). However, several questions remain con-
cerning the significance of this assay (e.g., results of
unburned cigarette [control] analysis; geographic location
of the conducted studies, etc.).
k) Dow reports that it identified polychlorinated
dibenzofurans (PCDFs) in a number of the analyzed environ-
mental samples. This finding should be investigated in
more detail in .light of the high toxicity of several PCDF
isomers.
Overview
In summary, Dow1s efforts "to identify the potential sources
of the chlorinated dioxins" found in the Tittabawassee
River indicate that it is possible that some portion, likely
quite small, of the PCDDs identified in Tittabawassee River
fish may have originally been formed and released to the
environment as a combustion by-product rather than as a
direct water effluent release as suggested by the information
in the original submission. An important consideration,
however, is that (with the exception of some OCDD) PCDDs
were not detected in fish collected upstream from Dow's
Midland, MI plant. Therefore, the available information
(especially point (d) above) continues to suggest that the Dow
Chemical Company's Midland, MI plant represents the major,
if not the only, source of the TCDD contamination found in
the Tittabawassee and Saginaw Rivers and Saginaw Bay in
Michigan.
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Current Production and Use
polychlorinated dibenzb-p-dioxins are impurities that may be
formed as unwanted contaminants under certain conditions
during the production of chlorophenols. For example,
2,3,7,8-TCDD has been identified as a contaminant produced
during the manufacture of 2,4,5,-trichlorophenol (2,4,5,-
TCP) by current production methods. Because of this, 2,4,5-
trichlorophenoxy acetic acid (2,4,5,-T), a registered
pesticide derived from 2,4,5-TCP, is also potentially
contaminated with 2,3,7,3-TCDD from the TCP intermediate.
Comments/Recommendations
a) This submission and status report should be trans-
mitted to OPP, SAD, CAD, PID, LTAT (AD), OE, OWWM, OGC,
OAQPS, ORD, OMSAPC, Region V, Michigan Department of Natural
Resources, CPSC, USDA, FDA, OSHA, NIEHS, and NIOSH.
b) The submitter should be asked to provide the
clarifications outlined in the status report and appendix.
The submitter should be asked to prepare a written response
to the questions; in addition, a meeting between Dow and EPA
is suggested to provide a full discussion of the scientific
aspects of the submission.
c) The development of a Sources/Effects Report (Phase
I document) on PCDDs is recommended. This activity should
also include consideration of the polychlorinated dibenzofurans
(PCDFs).
d) Controlled combustion studies are needed to evaluate
Dow's hypothesis that PCDD synthesis occurs in most combustion
processes as well as to indicate the scope of any future
monitoring effort.
e) SAD (OPII) should initiate consideration of an
appropriate monitoring program to determine the degree and
extent of PCDD contamination in Midland, MI, as well as
other current or historical sites of possible PCDD contami-
nation (e.g., chlorophenol manufacturing, processing, or
disposal sites). Environmental monitoring for PCDFs should
also be considered. These efforts should be closely coordi-
nated with ongoing or contemplated activities in other EPA
offices (e.g., OPP, IERL/Cinn., OWWM, OAQPS, Region V,
etc.).
f) OTS efforts to assess the sources and extent of
PCDD and PCDF contamination as well as possible control needs
should be closely coordinated with the efforts of other EPA
offices and federal agencies by PID (OPII), possibly through
intra-agency work, groups and the Regulatory Development Work
Group of IRLG, respectively. All of these efforts should be
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coordinated with the designated Headquarters Coordinator
for all dioxin-related activities.
g) An 8(d) rule to collect health and safety studies
on PCDDs and PCDFs should be considered.
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APPENDIX (8EHQ-1178-0209) (Supplement)
The polychlorinated dibenzo-p-dioxins (PCDDs) are a series
of tricyclic aromatic compounds which exhibit similar
chemical and physical properties. The basic structure of
PCDDs (as shown below) has eight possible points of chlorine
substitution. From the monochloro to,the octachloro deriva-
tives, a total of 75 different positional isomers is possible.
The most extensively studied isomer of the PCDDs is 2,3,7,8-
tetrachloro dibenzo-p-dioxin (2,3,7,3-TCDD), one of the most
potent toxins presently known. The toxic effects induced by
other TCDD isomers are less well characterized; however,
they appear to exhibit a lesser degree of toxicity (both
quantitatively and qualitatively) than 2,3,7,3-TCDD. For
these reasons, the PCDD isomer attracting the greatest
amount of Agency interest and activity is 2,3,7,8-TCDD.
Submission Evaluation
(The following sections refer to
subheadings in Dow's report.)
I. Building Blocks for Chlorinated Dioxins
The report's conclusions state that "conditions in a flame
favor the occurrence of every conceivable type of chemical
reaction" (p. 5) , so tlvit PCDDs may be formed in trace
quantities wherever co.xufcustion occurs. The formation of
polycyclic organic compounds during combustion is not a new
finding. During coal combustion, the initial pyrolytic
reaction can result in fragmentation, ring closures, conden-
sation, and aromatization. The main products tend to be
polynuclear ring compounds, occasionally containing nitrogen,
oxygen, or sulfur, and simple compounds like H0, H0S, NH-.,
CH4, C02, etc.
Dow opens the discussion in Part I by establishing that
inorganic chloride, gaseous products (SO0, NO , CO, etc.),
metals (V, Fe, Ni, etc.), and a wide variety of aliphatic
and aromatic hydrocarbons are present during refuse- or
fossil-fueled combustion reactions. The submitter then
postulates that "at ultratrace levels, parts per billion,
the number of compounds which may possibly form on particu-
late matter approaches or exceeds that presently known to
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man." While this statement may be true, it is never linked
experimentally in Dow's submission to a demonstration that
PCDDs will typically form during combustion reactions.
Several authors (e.g., Buser et al. [Chemosphere, 7(2),
165, 1978]; Rappe et al. ;[Chemosphere, 7(3), 269, 1978],
Stehl and Lamparski [Science, 196, 1008, 1977]; Ahling et
al. [Chemosphere, 6(8), 461, 1977]; Buser and Rappe [Chemosphere,
7T2) , 199, 1978]), on the other hand, have demonstrated in a
laboratory setting that PCDDs can be formed during the
pyrolysis of polychlorophenates (sodium salt) or polychloro-
phenoxy-containing materials (e.g., polychlorophenate-
impregnated leaves, wood shavings, plywood, or waste oil).
Rappe et al. (1973) stated that the concentration of PCDDs
in the combusted samples represented a sizeable increase
over the levels detected in the original polychlorophenate
samples.
IV. Airborne Particulate Matter
Soil samples were collected from "13 different locations
inside and outside (Dow's) Midland Plant" and analyzed for
tetrachlorodibenzo-p-dioxin (TCDD), hexachlorodibenzo-p-
dioxin (HxCDD), heptachlorodibenzo-p-dioxin (HpCDD), and
octachlorodibenzo-p-dioxin (OCDD). Dow does not further
identify the sites with respect to individual locations or
distances from the plant or specific plant operations. The
analytical results are presented in Table 1. Dow notes that
the analytical method was not validated and, therefore, the
results are qualitative only.
Table 1. PCDDs in 13 Midland Soil Samplesa
(taken from p.17 of Dow's report)
TCDD HxCDD HpCDD OCDD
4/13 9/13 13/13 13/13
a) Collected from "inside and outside the Midland
plant."
A second set of soil samples was collected in the same
manner; 5 of these, "including the ones corresponding to
those that previously gave positive TCDD results, were
analyzed by a newly developed and validated analytical
method." Dow goes on to state that this new method per-
mitted the separation of the 2,3,7,8-TCDD from "almost all
of its other 21 isomers." These results are summarized in
Table 2. The specific sample selection sites represented by
Table 2 should be clearly identified as to their placement
with respect to the Dow plant.
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Dow's claim at this juncture and at subsequent points in the
submission that its analytical method permitted separation
of TCDD isomers is not adequately supported by any of the
figures shown in the submission or the attached appendices.
Dow should be asked to provide a detailed description of the
methods of extraction and analysis as well as the criteria
utilized in the identification of TCDD isomers; e.g., (a)
GC/HRMS (gas chromatography/high resolution mass spectroscopy)
detection method, (b) elemental composition of molecular
masses m/e 320, m/e 322, and m/e 324, (c) molecular ion Cl
ratio, 0.8/1.0, (d) GC/HRMS retention time of test samples
and confirmatory samples fortified with specific TCDD
isomers, (e) m - COC1 loss, m/e 257, (f) use of and tech-
niques for GC/HRMS double ion monitoring, (g) a description
of the capillary column GC resolution measured in theoretical
and/or effective plates, and (h) a description of the degree
of GC resolution of specific TCDD isomers (Dow's tables
should be more specific and indicate identified isomers and
their contribution to the total value shown). In addition,
Dow should clarify if the quantified values of TCDD isomers
shown in its report are based on the response of specific
isomers or if the values are normalized to the response of
2,3,7,3-TCDD. Finally, there is some question that the harsh
(acid) conditions used for sample extractions may have
resulted in PCDD formation from precursers or by dechlorina-
tion of higher PCDD isomers. Dow should be asked to confirm
its findings by providing comparative results from neutral
extraction procedures, if available.
The information needs outlined in the preceding paragraph
concerning TCDD isomer values also apply in all cases to
HxCDD, HpCDD, and OCDD isomer values reported in the Dow
submission. Any available data on the presence of penta-
chloro dibenzo-p-dioxin isomers in environmental samples
should also be requested.
Dow states on p.2 of its report that the "analytical method-
ology is so very new that it has not always been validated
and not yet corroborated by other scientists." Limited
analytical significance can be derived from results generated
using nonvalidated procedures. In order to derive significant
and valid analytical meaning and/or conclusions from the
results of part per billion (ppb) and part per trillion
(ppt) analysis for PCDDs, the results must be accompanied by
(1) appropriate quality control results and (2) a complete
description of the criteria utilized to identify and confirm
the presence of PCDD residues. Furthermore, in cases where
the reported PCDD residue levels and the limit of detection
are of identical or approximately equal value, such numbers
have uncertain analytical significance especially in situations
when nonvalidated analytical methods are employed. PCDD
values which are not greater than ten times (10X) the noise
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have been identified with an asterisk (*) in this status
report. (When analyzing for trace levels of PCDDs, .a
signal to noise ratio of 2.5:1 is considered to be the level
of detection; values below this ratio are reported as non-
detected [ND]. When a sufficient amount of the sample and
time are available to the analytical chemist, samples having
a signal to noise ratio between 2.5:1 and 10:1 should be
rerun a second time to verify the result. If the second
analysis falls between 2.5:1 and 10:1, the two separate
results and the average should be reported. Values result-
ing from a single analysis are not contested if the signal
to noise ratio is at least 10:1 and the ratio of peak heights
m/e 322:m/e 320 is in the proper isotopic proportion.)
Table 2.
PCDDs in 5 Midland Soil Samples5
(taken from Dow's Table III)
Sample
1
2
3
4
TCDD isomers
other than
2,3,7,8-TCDD
17
9
18
13
0.8
2 ,3 ,7 , 8-TCDD*
16
6
100
16
HxCDD
230
40
120
280
0.3
HpCDD
3200
470
650
240
70
490
a) Taken from "inside and outside the Midland plant."
b) Values are reportedly based on the "separation of
the 2,3,7,3-TCDD from almost all of its 21 other
isomers" (see discussion in the text),
Next, dust samples were collected at various locations in a
"Dow research building" and subsequently extracted and
analyzed using a method reportedly separating "the 2,3,7,3-
TCDD from all but about 11 of its isomers". (As discussed
earlier, this statement should be supported by documentation
indicating that eleven TCDD isomers plus the 2,3,7,8-TCDD
equals one fraction. Dow's statement to that effect is not
sufficient.) The results of this work are presented in
Table 3. Dow should be asked to clearly describe what it
means by the term "air intake." Does the PCDD contamination
of this air intake dust result from the handling of "inside"
or "outside" air?
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Table 3. Dust Samples from a Dow Research Building (ppb)
(taken from Dow's Table IV)
Sample
1st floor
1st floor
2nd floor
2nd floor
TCDD isomers
other than
2,3,7,8-TCDD
0.5
2.3
1.3
2nd floor 1.5
(2 weeks after
cleaning)
air intake 2.3
2,3,7,3-TCDDc
1.0
2.3
2.6
0.7
1.2,
2.3
HxCDD HpCDD OCDD
35* 1200 7500
a) Values are reportedly based on the "separation of
the 2,3,7,8-TCDD from all but about eleven of its
isomers" (see discussion in the text).
*Value is close to the detection limit for the analytical
method employed (signal is less than 10X noise).
Additional dust samples from Midland and an unspecified
"metropolitan area" were collected and analyzed for control
purposes. These samples did not satisfy this need, therefore,
dust and soil samples wer^ collected from additional, vaguely
characterized ("rural," "urban," and "major metro") sites.
Table 4 represents a composite presentation of these results.
Dow concludes (p.21) that these data (Tables 1-4) "strongly
support the conclusion that chlorinated dioxins are produced
in incinerators and fossil fueled powerhouses as a consequence
of combustion. These results indicate that chlorinated
dioxins are more widespread than previously anticipated and
are perhaps ubiquitous". In point of fact, the results
presented offer no scientific documentation (other than
weakly circumstantial evidence) relating Dow's observations
on PCDD contamination of soil and dust to the synthesis of
PCDDs as a by-product of incineration or power generation.
There is some circumstantial evidence that the HxCDD,
HpCDD, and OCDD identified in the soil samples from the
urban and the metropolitan areas may be associated with the
operation of a powerplant and an incinerator, respectively.
This, however, does not demonstrate that the presence of
these substances results from their synthesis as a normal
combustion by-product. Table 5 presents a comparison of the
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total number of PCDD-positive samples collected from the
Midland, MI area with those collected from other locations.
From Table 5, the following observations, contrasting Dow's
claims, can be supported:
(a) Midland, MI, and especially the area around the
Dow plant, exhibits the greatest evidence for
gross PCDD contamination among the various locations
sampled. This is true both in terms of the propor-
tion of samples in which PCDDs were detected and
the degree of contamination evident in individual
samples. In the latter case, the levels of PCDDs
found in Midland are 2-4 orders of magnitude
greater than those reported at other locations.
The fact that much higher levels of PCDDs were
found in the soil and dust arour.i the Dow chemical
plant as compared to urban, metropolitan, and rural
areas suggests that polychlorophenol production or
some other activity (spills, plant emissions,
combustion of chemical wastes, etc.) at the Dow
plant may be the source of the observed PCDD
contamination.
(b) To the extent that TCDDs, especially 2,3,7,3-TCDD,
are the PCDDs of greatest Agency concern, the levels
of TCDDs identified in Midland soil and dust samples
indicate that this area represents a definite TCDD
"hot spot." In comparison, there are very few
instances where TCDDs were reported at other sites.
V. Incineration
in its introduction to this section, Dow cites several
European authors who have reported the presence of PCDDs in
fly ash and flue gas from municipal incinerators (Olie et
al., Chemosphere, 6(8), 455, 1977), in fly ash alone from a
municipal incinerator, and in fly ash from an industrial
heating facility (Buser et al., Chemosphere, 7(2), 165,
1973). Dow notes (p.22) that Olie et al. postulate that the
PCDDs are formed as a result of the thermal condensation of
chlorophenols, although mention is made in the article that a
thermal synthesis reaction involving inorganic chloride and
organic material (especially hexachlorobenzene and other
highly chlorinated benzene) "was considered to be entirely
possible." Dow, however, fails to discuss aspects of the
Buser et al. (1973) study as well as a Rappe et al.
(Chemosphere, 7(3), 269, 1978) study which indTcate that the
pattern of PCDD isomers identified in fly ash (from incinera-
tors and heating facilities) was almost identical to that
found when a mixture of polychlorophenates was pyrolyzed
under controlled conditions. Buser et al. go on to state
361
-------
Table 4.
PCDDs in Soil and Dust Samples (ppb)
(taken from Dow's Tables III, IV, V, and VI)
Sample
Midland
TCDD
HXCDD
HpCDD
OCDD
(1) 0.03* 0.2 2.3 19
(2) 0.04* 0.4 3.9 31
(3) See Tables 2 and 3 for other Midland values.
Rural
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(3)
Urbana
(1)
(2)
(3)
(4)
(5)
Major Metro
(1)
(2)
(3)
(4)
(5)
(6)
(7)
(3)
(9)
(10)
(11)
(12)
(13)
(14)
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
0.03
ND
0.006*
0.005*
0.005*
ND
ND
0.04*
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
1.2
ND
0.03*
ND
ND
ND
0.03*
0.31
0.12*
0.14
0.04*
0.09*
0.02*
ND
0.34*
0.09
0.1
ND
0.3
ND
ND
ND
0.3*
0.05*
0.02*
ND
0.03*
1.6
0.23
0.30
ND
0.035*
0.14
0.24
3.3
1.4
0.85
0.36
0.96
0.10
0.64
3.2
0.3
0.3
ND
1.0
ND
0.1*
ND
0.10
0.17
0.16
ND
0.11*
2.0
0.96
2.0
0.05*
0.20
0.41
1.0*
22.0
8.5
3.2
1.4
6.0
0.35
2.6
8.2
3.5
0.4
ND
3.3
a) Samples collected from between 300-1500 feet from a
"powerhouse."
b) Samples collected from between 100-3300 feet from an
"incinerator" (except for (14) which was collected at
a "metro river shoreline").
*Value is close to the detection limit for the analytical
method employed (signal is less than 10X noise).
ND) Signal not detected at 2.5X noise.
362
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Table 5. A Comparison of PCDD-Positive Soil and Dust Samples/
Total Analyzed from Different Locations
Location
Midland, MI
Other Locations
(total)
TCDD Isomers
16/25a (64%)b
(0.03-18)°
5/23 (22%)
(0.005-0.04)
2, 3, 7, 3 -TCDD
HxCDD
HpCDD
to
u>
Rural
Urban
Major Metro
0/8 (0%)
0/5 (0%)
5/10 (50
(0.005-0
(100%) 22/26 (33%) 26/26 (100%)
(0.3-100)
(0.2-280)
(2.3-3200)
10/23 (43%) 18/23 (78%)
(0.02-1.2) (0.02-3.3)
0/8 (0%)
2/5 (40%)
(0.03-1.2)
4/8 (50%)
4/5 (80%)
(0.035-1.6)
8/10 (30%) 10/10 (100%)
(0.02-0.34) (0.10-3.3)
OCDD
26/26 (100%)
(19-20500)
20/23 (87%)
(0.05-22.0)
5/8 (63%)
5/5 (100%)
(0.05-2.0)
10/10 (100%)
(0.35-22.0)
a) This entry reportedly represents TCDD isomers other than 2,3,7,3-TCDD;
i.e., the analytical method is claimed to have achieved some degree of
TCDD isomer separation. All other entries in this column apparently represent
aggregate totals for all TCDD isomers.
b) Percent (PCDD-positive samples/location). Note that for purposes of this
table, asterisked (*) values taken from Tables 3 and 4 were considered
"positive" despite questions as to the analytical significance of some of
these values.
c) Range of detected levels in ppb.
d) This entry reportedly represents some degree of separation of the 2,3,7,8-TCDD
from other TCDD isomers.
-------
that available evidence indicates that commercial chloro-
phenols cannot be excluded as the precursor to PCDDs in fly
ash. As noted briefly in the dicussion of part I, Rappe et
al. (among others) have also shown that the combustion of
leaves, wood shavings, plywood, or waste oil containing
chlorophenates can yield a variety of PCDD isomers in the
ash. Dow reports that it operates two major chemical waste
incinerators at Midland, MI. The first is a large stationary
tar burner and the second is a rotary kiln incinerator.
Samples of particulate matter were removed from the stacks
and analyzed for PCDDs. The resulting data are summarized
in Table 6. Particulates from the stationary tar burner and
the rotary kiln incinerator show no detectable TCDD when
operated with supplementary fuel. (The levels of the other
PCDD isomers are, nonetheless,itill relatively high.)
However, when the rotary kiln incinerator is operated
without supplemental fuel, extremely high levels of TCDDs
(and other PCDDs as well) are detected. Several important
questions immediately arise. Does Dow generally operate the
rotary kiln incinerator with supplemental fuel when using it
for chemical waste incineration? Dow should specify the
types and conditions of operation of air pollution control
devices (including scrubbers) used to control particulate
emissions from these incinerators? It is also important to
know whether the particulate samples were collected from the
stacks "upstream" or "downstream" from the scrub water inlet
(i.e., before or after scrubbing) (see part VII below). In
addition, were the particulates scraped from the walls of
the stacks or were they collected from the gas phase or an
electrostatic precipitator (or some other pollution control
device).
VI. Powerhouses
Partioulates from a Dow Midland powerhouse stack were col-
lected and analyzed. Fuel oil and coal are burned in the
powerhouse. The results of the PCDD analyses are presented
in Table 7.
It is not clear why the TCDD isomers (other than 2,3,7,8-
TCDD which was not detected) are so high (compared to other
PCDDs) in the powerhouse particulate. Likewise, if Dow's
thesis concerning the synthesis of PCDDs as a normal combus-
tion by-product is correct, why do the incinerators as
opposed to the powerhouse, in general, show higher levels of
PCDDs in the fly ash? The difference may be related to the
nature of the material being burned in each operation.
One possible explanation is that the chemical wastes being
burned in the incinerators already contain PCDDs or PCDD
precursors (polychlorophenoxy material); that is, the wastes
364
-------
Table 6. PCDDs in Particulate Matter from Dow Incinerators (ppb)
(taken from Dow's Tables VIII and IX)~
Sample
(1)
(2)
(3)
(4)
(5)
TCDD isomers
other than
2,3,7,8-TCDD
2 , 3 ;,7', 8-TCDD'
HxCDD HpCDD
OCDD
Stationary tar burner (with supplemental fuel)
ND
ND
ND
ND
ND
ND
ND
ND
ND
ND
20 90 330
7 125 440
6 60 190
4 160 320
1 27 250
(1)
(2)
(3)
(4)
(5)
a)
Rotary kiln incinerator (without supplemental fuel)
(1)
(2)
(3)
(4)
1,800
5,000
3,300
12,000
2,300J?
8,200D
110
ND
13,000
65,000
1,300
5,600
110,000
510,000
2,000
37,000
180,000
310,000
3,000
59,000
Rotary kiln incinerator (with supplemental fuel)
ND
ND
ND
ND
ND
1.4
ND
ND
5.0
4.0
13.0
4.0
6.0
27.0
110.0
30.0
9.0
15.0
170.0
950.0
ND
ND
ND
ND
ND
Dow1s report does not specify the number of TCDD
isomers represented by values in this column.
b) These values may be high; see Dow's comment on p.24.
Table 7. PCDDs in Particulates from a Powerhouse Stack (ppb)
(taken from Dow's Table X)
TCDD isomers
other than
2,3,7,8-TCDD
33*
2 , 3 , 7 , 3-TCDD'
ND
HxCDD
HpCDD
4
OCDD
24
a) Dow1s report does not specify the number of TCDD
isomers represented by this value.
*Value is close to the detection limit for the analytical
method employed (signal is less than 10X noise).
,365
-------
result from Dow's chlorophenol production processes. Rappe
et al. (1978) offer several different mechanisms for the
formation of PCDDs given the presence of pre-formed PCDDs or
PCDD precursors. The 3 proposed mechanisms are:
a) by dimerization of chlorophenates,
b) by dechlorination of higher chlorinated PCDDs, and
c) by cyclization of PCDD precursors.
VII. Waterborne Particulates
Composite scrubber water samples were taken from the rotary
kiln incinerator during the same sampling reported in part V
of the report. Particulates were filtered from the scrubber
water and both the particulates and the water filtrate were
analyzed for PCDDs. (Note that Dow's analytical method ML-
AM-78-63 [Dow's Appendix B3] [specific for soil, dust, and
particulate samples] was used to analyze the scrubber water
particulates. Dow, however, does not specify the analytical
method used to examine the water filtrate. This should be
clarified.) Table 3 presents the results of these analyses
and also compares the scrubber water PCDD values with those
reported for rotary kiln fly ash (previously reported in
Table 6). When comparing the PCDD levels reported in the
different samples, it should be noted that there is no
indication whether all the samples were taken within a.short
time of each other or days apart. In addition, it is not
clear if the same wastes were being burned or if similar
incineration conditions existed when the respective samples
were taken. Dow should be asked to provide a complete
description of the operating conditions (normally and during
sampling), nature of the wastes burned normally and during
sampling, and use of air pollution control devices on the
rotary kiln incinerator. Dow should also describe the
method of disposal used for scrubber water particulates and
any other solid wastes resulting from these incineration
procedures.
In addition, Dow should provide the same information for its
stationary tar burner.
VIII. Combustion of Dioxins
The U.S. EPA report entitled "At-Sea Incineration of
Herbicide Orange Onboard the M/T Vulcanus" (EPA-600/2-
78-086) was published in April, 1978. A copy of this
publication should be transmitted to Dow in any followup
to this submission.
366
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Table 8. PCDPs in Rotary Kiln Scrubber Water and Stack
Fly Ash(ppb)
(taken from Dow's Tables IX, XI, and XII)
Without supplemental fuel
Sample
A) scrubber water
particulates
TCDD isomers
other than
2,3,7,8-TCDD
300
B) scrubber water 0.0018*
filtrate
C) fly ash .
particulates
2,3,7,3-
TCDD HxCDD HpCDD OCDD
2,200'
0.001'
3,400 26,000 42,000
0.005 0.24 0.026
(1) 1,800
(2) 5,000
(3) 3,300
(4)12,000
2,800
8,200
110
ND
13,000
65,000
1,300
5,600
110,000
510,000
2,000
37,000
180,000
310,000
3,000
59,000
With supplemental fuel
D) scrubber water
particulates
14
E) fly ash . (1) ND
particulates (2) ND
(3) ND
. (4) ND
(5) ND
32'
ND
ND
ND
ND
ND
200
970 1,200
1.4
ND
ND
5.0
4.0
13.0
4.0
6.0
27.0
110.0
30.0
9.0
15.0
170.0
950.0
a) The analytical method reportedly did not separate
the 2,3,7,8-TCDD from 11 other isomers.
b) The high results reported for 2,3,7,3-TCDD "are
probably due to analysis by the non-specific GC-MS packed
column method" (see p.24 of Dow's report). In addition,
Dow1s report does not specify the number of TCDD isomers
represented by the values in the 2,3,7,8-TCDD column.
*Value is close to the detection limit for the analytical
method employed (signal is less than 10X noise).
367
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IX. Michigan Division Manufacturing Plants as Potential
Sources of Trace Levels of Chlorinated Dioxins in the
Environment
A. Wipe testing
The fact that 8 out of 230 wipe tests gave positive results
for TCDD merits consideration. The wipe test area, 100
cm i is roughly equivalent to the area of a human hand and
1 ug TCDD may be approaching a toxic level (LD_0 male guinea
pig, 0.6 ug/kg). The text indicates that the analyses were
conducted by gas chromatography with a detection limit of
1 ug/wipe; however, Appendix B4 states that analyses were
carried out by GC-MS with a level of detection of 0.1 ug/
sample. These points should be clarified. In addition,
information as to the suitability of the wipe test method-
ology to actual conditions which might be encountered in
the Michigan Division manufacturing plants should be provided
by Dow.
B. Air monitoring
The method of sample collection is not described in suffi-
cient detail in Dow's report. Are particulates sampled
during this procedure? Also, note that part of the report
appears to have been omitted at the top of page 30. This
omission should be clarified.
A statement made on p.30 could be misleading. "The few
molecules that take this path (vaporization) will be destroyed
by photodegradation within a few hours even when the day is
cloudy (23)." This statement could lead one to believe that
if PCDDs are released to the atmosphere they will be destroyed.
If these compounds are really volatilized then they could
possibly be decomposed; however, if they are adsorbed onto
fly ash or other particulate matter they would probably not
be destroyed photolytically or to only a limited extent. In
addition, the applicability of Dow's reference 23 (Nash and
Beall, 1977) to the above quotation is not clear; clarification
is required.
Dow claims on page 30 that the "wipe testing and air monitoring
data are strong evidence that (Dow) manufacturing plants do
not emit levels of chlorinated dioxins sufficient to explain
the finding of these compounds in the soil samples reported
earlier." No scientific basis for this conclusion is provided
in the data presented by Dow. In the first place, there is
no way to compare the ppb levels of TCDD found in soil and
dust with the "1 ug/wipen values reported for the wipe
testing. To support its conclusion, Dow would either have
to "wipe test" soil samples or, preferably, analyze pesticide
plant wipes on a ng/g (ppb) basis. Handled in any other
way, one is left to compare apples with oranges. Similarly,
368
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there is no way to compare D'ow's plant air monitoring data
with the PCDD values reported for soil and dust samples
collected outside the plant. Furthermore, there is no
indication as to the location of each wipe test or air
sampling site in relation to the various operations involved
with polychlorophenol production or handling. Dow should
present a grid of its polychlorophenol production and
handling sites and identify the sampling points for the 230
wipe tests and 35 air monitoring assays. Any available
monitoring data (wipe tests, air sampling, etc.) regarding
Dow laboratory facilities as potential sources of PCDD
contamination should also be provided.
C. Aqueous streams
Further information on the "tests" for primary organics
reported in this section should be provided by Dow.
D. Cooling waters
The results of Dow's analyses of cooling tower "residues"
for PCDDs are shown in Table 9. It is important to know if
these towers cool steam or other effluent streams from the
polychlorophenol facilities, the power plants, or the incinera-
tors discussed earlier. Dow should provide a map of its
plant site showing the location and relationship of each
cooling tower, incinerator, powerhouse, and production
facility (especially those producing or handling polychloro-
phenols or derivatives). In addition, Dow should further
describe what it means by "cooling tower residue"; is this
a water or sediment sample? Dow should also support with
analytical results its statement on page 30 that "product
leaks to cooling towers" do not occur.
Table 9. PCDDs in Cooling Tower Residues
(taken from Dow's Table XIII)
Location
TCDD
Northwest ND (L.O.D.
0.05)a
East ND (L.O.D.
0.05)
Central #1 1.6*
Central #2 6.0
HxCDD
ND
ND
10
HpCDD
25
12
20
a) Level of detection was 0.05 ppb.
*Value is close to the detection limit for the analytical
method employed (signal is less than 10X noise).
369
-------
Dow states in this section (p.30) that "(it) was assumed
that cooling tower residues would be positive for chlorinated
dioxins." Dow should be asked to provide the basis for this
assumption. On page 31, Dow states that "(from) these data
(see Table 9), we conclude that the presence of chlorinated
dioxins in cooling tower residues confirms the airborne
route." Dow should b6 asked to explain the term "airborne
route" and specify the sources of the PCDDs found in cooling
tower residues.
Central to this discussion of cooling towers is the assumption
that Dow does not use 2,4,5-trichlorophenol in its cooling
tower waters as a biocide. Dow should be asked to clarify
this point. In the event that Dow does use 2,4,5-trichloro-
phenol, then the PCDDs found in the cooling tower residues
may not be from airborne particulates.
E. Various aqueous streams
For this part of the report, Dow sampled various aqueous
streams in its Midland plant. The samples were collected
from sewer lines before they entered the waste treatment
plant. The samples were selected on the basis of "the
stream source and its rate of flow." This vague description
of the samples is inadequate. Do any of the sampled aqueous
streams come directly from chlorophenol production or handling
operations? Do these samples include particulates? If
not, these analyses have limited value. Dow indicates it
employed analytical method ML-AM-73-97 (Appendix B2) for the
analyses reported in this section. The method is specified
for the analysis of fish and soil samples; its applicability
to aqueous stream analysis should be demonstrated.
O*i page 32, Dow states that in the case of sewer water
analyses, "the source of the chlorinated dioxins cannot be
reliably determined by the ratio of the various species."
However, in immediate juxtaposition to this statement is
Dow's remark (p.33) that "(with) the exception of sewer
water samples 2 and 4 and cooling tower central £1, the data
indicate that the chlorinated dioxins are from the same
source as those on soil and dust. The exceptions have
species whose ratios are similar to those found on particu-
lates from the powerhouse." Dow should clarify the meaning
and significance of these remarks. Insofar as Dow states in
the Introduction (p.2) that "(samples) were not taken by
statistical design and results are not intended to represent
anything other than the sample analyzed," how can Dow proceed
to compare the PCDD ratios from one sample with those from
another? Moreover, how can Dow draw conclusions from such a
comparison? Furthermore, how can the submitter state in one
paragraph that a comparison of PCDD ratios will not yield a
370
-------
"reliable" determination of- the source, but then in the next
paragraph draw 2 separate and distinct conclusions from
these same ratios.
Another statement on page 33 deserves comment: "The (PCDD)
ratios (found in the cooling tower or sewer waters) do not
fit those normally found in any manufactured product." The
meaning of the phrase "normally found in any manufactured
product" is not clear because no known polychlorophenol
product or derivative contains both TCDD and OCDD. In
general, trichlorophenol contains TCDD, while pentachloro-
phenol contains HxCDD, HpCDD, and OCDD but no TCDD. If Dow
is aware that any of its products contain both TCDD and
OCDD (or for that matter, both trichlorophenol and penta-
chlorophenol) , it should so inform the Agency. Dow should
describe the spatial relationship of its trichlorophenol
production facility to the location of its pentachlorophenol
production site. Are any waste water lines common to both?
What is the composition of the chlorophenol wastes incinerated
by Dow? Do these wastes represent a composite of both
trichlorophenol and pentachlorophenol wastes? Or are wastes
from the two chlorophenol production processes burned sequen-
tially in the same incinerator?
X. Chlorinated-dioxin Containing Particulate Matter from
Mufflers
DOW reports trace quantities of PCDDs in scrapings taken
from the inside of car and diesel truck mufflers. The cars
sampled were equipped with and without catalytic converters.
Does this necessarily mean, as Dow advances, that PCDDs are
formed during combustion in the engine? If the car or truck
was driven primarily in an industrial area or near sources
that might be considered contaminated with PCDDs or PCDD
precursors, airborne particulates containing these substances
could be drawn into the air intake of the engine. Any
PCDDs not decomposed in passage through the engine might
then be deposited in the muffler. The statement (p.35) that
PCDDs "are in particulate emissions from internal combustion
engines" cannot be supported because vehicles' exhaust gases
were not analyzed. The only conclusions that can be supported
by the observations presented in this section are that (1)
PCDDs have been identified in some muffler scrapings, however,
(2) the source of the PCDDs is unknown.
The analytical method (GC-EC vs. GC-MS) used to detect
TCDD isomers was not specified in Dow's Table XV; this
information should be provided.
371
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XI. Commonplace Sources
1. Soot from fireplaces
Dow reports that soot collected from 2 fireplaces contains
PCDDs. The results are presented in Table 10. Dow states
(pp. 35 and 36) that none of the wood burned in the fire-
places "had been treated with any wood preservatives." Dow
should be asked to document this statement.
2. Particulate matter from a home electrostatic precipitator
The results of PCDD analysis performed on this sample are
presented in Table 10.
Table 10. PCDDs in Fireplace Soot and Particulates
from a Home Electrostatic Precipitator (ppb)
(taken from Dow's Table XVI)
TCDD isomers
other than
Source 2,3,7,8-TCDD
0.27
fireplace
A
fireplace
B
ND
electrostatic 0.40*
precipitator
2,3,7.3-
TCDD
0.1*
ND
0.6*
HxCDD HpCDD OCDD
3.4 16 25
0.23 0.67 0.39
34 430 1300
a) Dow's report does not specify the number of TCDD
isomers represented by values in this column.
'•'Value is close to the detection limit for the analytical
method employed (signal is less than 10X noise).
The geographic location of each house sampled in Table 9
should be provided by Dow. Were these houses in the Midland,
MI area, and if so were they near Dow's plant? This is of
some interest because the particulate collected in the
electrostatic precipitator (electronic air cleaner) have
a higher concentration of PCDDs than the soot samples from
the fireplaces (acknowledged sources of typical combustion
by-products). A home electrostatic precipitator functions
to a certain extent as a "high volume air sampler." In the
case cited by Dow, the electrostatic precipitator was operated
over a period of 6 spring and summer months. Thus, the
precipitator particulates analyzed by Dow represent airborne
372
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material collected over a 6 month .period which does not
coincide with the months generally associated with heavy
space heating-related combustion or home fireplace usage.
Therefore, the PCDD values for the home electrostatic
precipitator-collected particulates may, to a certain
extent, represent the results of incidental ambient air
"sampling" conducted at the site of the house. For this
reason, the location of this particular house may be important.
3. Charcoal broiled steaks
The results of this assay are presented in Table 11. As can
be seen, all samples were negative for TCDD and HxCDD and in
only one case (that being an "over-done" steak) did the GC-
MS (gas chromatography-mass spectrometry) method of analysis
"support" the GC-EC (gas chromatography-electron capture)
result. However, even in that case (as in all other
instances reported in the table), the reported OCDD residues
and the level of detection are of identical or approximately
equal value such that the number has limited analytical
significance. Furthermore, the blank sample (uncooked
steak?) had a concentration of 6 ppt of OCDD (determined by
GC-EC, although the value is so close to its level of
detection as to have limited analytical significance). Was
this blank (uncooked steak?) contaminated with pentachloro-
phenol, a widespread environmental contaminant?
Table 11. PCDD Content of Charcoal Grilled Steak (ppb)
(taken from Dow's Table XVII)
Sample
blank
medium-rare
well-done
over-done
TCDD isomers
other than
2,3,7,8-TCDD
ND
ND
ND
ND
2,3,7,8-
TCDD
ND
ND
ND
ND
HxCDD
ND
ND
ND
ND
GC-MS
ND
ND
ND
ND,
HpCDD
EC
0.004*
0.003*
0.006*
0.007*
OCDD
GC-MS
ND
ND
ND
EC
0.006*
0.005*
0.012*
*Value is close to the detection limit for the analytical
method employed (signal is less than 10X noise).
373
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XII. Cigarette Smoke
Cigarette smoke particulates were also analyzed for PCDDs;
the results are presented in Table 12.
Table 12. PCDDs in Cigarette Smoke Particulates
(lO"12 g/cigarette)
(taken from Dow's Table XVIII)
Location TCDD isomers
of purchase other than 2,3,7.8-
and test 2,3,7,8-TCDD TCDDa HxCDD HpCDD OCDD
urban 1 ND ND 8.0 8.5 50
urban 2 ND ND 4.2 9.0 13
a) Dow's report does not specify the number of TCDD
isomers represented by values in this column.
Several questions arise concerning this assay. Are PCDDs or
PCDD precursors present in unburned cigarettes (possibly due
to pesticide use of polychlorophenols^or derivatives)? How
does 10" g/cigarette relate to 10~ g/g (or ppt)? The
cigarettes were smoked in two unidentified "urban locations";
why was this method chosen over a controlled study conducted
in a lab? Were the cigarettes "smoked" near Midland, MI or
some other industrial site; in other words, how would the
results of ambient air sampling at the two locations compare
with the reported cigarette-PCDD values? Do the individual
results in Dow's Table XVIII represent GC-EC or GC-MS
analysis? Are the methods confirmatory in their results?
XIII. Other Chlorinated Compounds Identified
The polychlorinated dibenzofuran (PCDP) findings reported in
this section should be investigated further. Several investi-
gators (Buser et al., Chemosphere, 7(5), 419, 1973a; Rappe
et al., Chemosphere, 7(5) , 431, 1978; Buser et al., Chemosphere,
7(5), 439, 1978b; Rappe et al. , Chemosphere, 6(5), 231,
1977; Buser et al., Chemosphere, 7(1), 109, 1973c; etc.)
have identified PCDFs in polychlorophenol pesticides, saw
dust from polychlorophenol-treated wood, fly ash, PCB mixtures,
and as a by-product of the combustion of PCBs. Of significance
are the Buser et al. (1973a) findings that the major PCDF
constituents (in fly ash as well as in PCB pyrolyzates)
tended to be the most toxic PCDF isomers (2, 3,7,8-tetra-CDF;
1,2,3,7,3-penta-CDF; and 2,3,4,7,3-penta-CDF). This contrasts
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with the Buser et al. (1978a) findings on the distribution
of PCDD i§ojner§~rn polychlorophenate pyrolyzates where the
less toxic isomers were in greatest concentration.
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