United States . e Solid Waste and
Environmental Protection Emergency Response EPA530-R-94-021
Agency (5305) , April 1994
&EPA Exposure Assessment
Guidance for RCRA
Hazardous Waste
Combustion Facilities
DRAFT
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DRAFT -.'' V Revised April 22, 1994
Attachment ,
IMPLEMENTATION GUIDANCE FOR CONDUCTING
INDIRECT EXPOSURE ANALYSIS AT
RCRA COMBUSTION UNITS
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KOTICE: The recommendations- set out in this
document are hot final Agency "action, but are intended
solely as guidance. They are not intended, nor can they
be relied upon, to create any rights enforceable ,by any
party in litigation with the United States. EPA
officials may decide to follow the guidance provided in
this memorandum, or to act at variance with the guidance,
based on an analysis of specific site circumstances. The
Agency also reserves the right to change this guidance.
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-1. WHO PERFORMS RISK ASSESSMENTS . - .
With respect to the facility-^specific risk assessments, the
Draft Waste Minimization and Combustion Strategy (also referred to
as Draft Strategy) indicates that risk assessments should be
performed prior to permitting, generally by EPA Regions or the
authorized State. . ' \ ,
' - ,- ' ,.,'... . . . ' "
Several questions have been raised on whether close Regional
or State supervision over facility owners and operators conducting
risk assessments could be an acceptable approach. For :example, in
certain cases, State law requires the owner/operator to,conduct the
risk assessment. Iyn addition, there may be other cases where the
Regions or States believe the facility may be in the best position
to conduct the risk assessment. To avoid needless duplication, the
Regions and States need not. conduct the assessments in those cases
but should be intimately involved in the planning and carrying out
of the risk assessment and should be formally reviewing and
approving the risk assessment protocols.
2. EMISSIONS ISSUES
, GUIDANCE ON LEVEL OF ORGANIC COMPOUND IDENTIFICATION REQUIRED
FOR RISK ASSESSMENT COMPONENT OF DRAFT STRATEGY
The EPA's Draft Strategy makes a full multiple-route risk
assessment a major component in the permitting of boilers and
industrial furnaces, and incinerators. To conduct the assessment,
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DRAFT , Revised April 22, 1994
EPA will need more extensive analysis of the chemicals identified
in the emissions to estimate risks from both direct and indirect
exposures. The risk assessment called for in Draft Strategy
involves two significant expansions from what was typically
conducted previously: (1) the number of routes of exposure will be
expanded and (2) the number of compounds analyzed and used in the
risk assessment will be expanded in order to identify as large a
fraction of the emissions as is realistically possible.
Guidance on Development of Facility-Specific List
While the actual list of compounds the facility must sample
and analyze is to be, determined by the permit writer, the following
guidance is offered to assist the permit writer in developing a
site-specific list.
a. The first list the permit writer should consider requiring the
facility to sample and analyze is the 12 metals currently
regulated under the BIF rule. (For boilers and industrial
furnaces, these metals must be addressed; for incinerators, it
is strongly recommended they be addressed.) The second list
the permit writer should consider requiring the facility to
sample and analyze are the compounds recommended in Table l of
Attachment A (a.k.a. the "PIC list"). The permit writer may
also want to include some of the compounds on Table 2 of
Attachment A. The compounds on Table 2 are currently being
evaluated and may be recommended at a future point in time.
b. Additionally, it is recommended that the permit writer also
require the analysis of the 20 largest peaks obtained in the
GC-MS analysis of the trial burn. This analysis will help EPA
determine whether there are any compounds that are not on the
attached PIC list but that are present in high amounts that
might significantly affect the risk.
c. The PIC list includes a full substituted dibenzo-p-dioxin and
dibenzofuran analysis. It is recommended that the permit
writer require the facility to perform this analysis in order
to identify compounds with resolution that will identify the
number of chlorine (or bromine or other halogens) molecules
and whether the congener has a halogen on the 2,3,7,8
positions. The purpose for this resolution is to calculate
Toxicity Equivalents (TEQs) which are used to calculate risk.
at the point of exposure. There are 7 possible
2,3,7,8-substituted dibenzo(p)dioxin congeners, ranging from
tetra-substituted to octa-substituted congeners, and
10 possible 2,3,7,8-substituted dibenzofuran congeners, also
ranging from tetra-substituted to octa-substituted congeners.
d. The PIC list also includes a full polychlorinated biphenyl
(PCB) scan. It is recommended that the permit writer require
the facility to perform this analysis in order to determine
the total PCB's. There are 209 possible PCB congeners,
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DRAFT Revised April 22, 1994
ranging from mono-substituted congeners to deca-substituted
congeners.
e The permit writer should also require the facility to sample
and analyze any additional highly toxic compounds that will be
in the trial- burn waste in high concentrations. The
formulation of the wastes used in the trial burn is intended
to provide a representative mixture of constituents that will
generate PICs that are characteristic of emissions from the
facility in permitted use so that the permit writer 'can
establish protective permit conditions. However, some of
these compounds may survive the combustion process and be
emitted intact. Hence, the list of principle feed
constituents should also be added to the list of compounds,for
which the facility should sample and analyze. See;
Attachment B, "Guidance on Trial Burns," for a full discussion
of factors to consider in the selection of waste constituents-
f The permit writer may also require sampling and analysis of
nitrogenated organic compounds. At this stage of development
of the draft PIC list, hot all of these compounds have been
added. It is anticipated that EPA's stack sampling program
will provide further guidance for nitrogenated PICs that the
permit writer may require of the facility. Nitrogenated PICs
are expected during the maximum temperature test. ,
g The permit writer may also require sampling and analysis of
any additional PICs that the permit writer believes are
important. , ' -.,-'..'.
Further guidance on the selection of compounds for analysis is
provided in the trial burn guidance;(Attachment B) .
Development of the PIC List , ,
The draft PIC list (i.e., Attachment A) was developed - from
existing data in EPA's possession as well as .lists of toxic
compounds from certain EPA programs. Since these lists were not
developed to be lists of toxic PICs, compounds have been Deleted
from the lists that appear to be inappropriate. EPA recognizes the
importance of using, specific focused studies to develop a PIC list
that .. is appropriately protective of the environment and not
excessively burdensome on the regulated community. However,^ OSW
considers It appropriate to use a draft list that is based on
existing data for an interim period. As EPA collects additional
PIC data, this list will be revised.
Source lists included:
* The hazardous waste constituent list in 40 CFR 261
Appendix VIII (Office of Solid Waste-OSW)
* The Hazardous Air Pollutants (HAP) list (Office of Air
"Quality Plcinning and. Standards-OAQPS)
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DRAFT Revised April 22, 1994
* Office of Research and Development list of organic
compounds found in combustion devices developed
for the Draft Addendum to the Indirect Exposure
Document (includes PICs found in hazardous waste
combustion devices and other combustion devices)
Inappropriate compounds were deleted from this list on the
following basis:
Compound was a pesticide that was unlikely to be a PIC
- Compound listed because it is an FDA regulated drug
- Compound listed because it is a carcinogenic sugar
substitute
- Listings that are not chemical specific,such as "coal tar"
- Compound for which EPA does not have a sampling and
analysis method delineated
- Metallic compounds were deleted because of difficulty in
analyzing the specific compounds; metals are still
included as-elemental totals
- If the compound had a low octanol-water partition
coefficient and did not have inhalation toxicity data
(i.e., it was not bioaccumulative and there was no
direct inhalation toxicity data, thus it would not
affect the risk assessment)
- The compound had low toxicity values
- Naturally occurring plant toxins
Certain compounds were kept on the list such as:
- Pesticides that have a molecular structure that is simple
enough to be of concern as a PIC
- Compounds with very high octanol- water partition
coefficients .
Planned Further Development of List
EPA is undertaking experimental studies specifically directed
toward determining which toxic organic compounds ai-e likely to be
formed in trace quantities from hazardous waste combustion devices.
The studies will explore variations in combustion conditions and
the effect on the specific organic molecules released. The studies
will also focus on defining operating parameters that can affect
the type, character, and quantity of PIC emissions.
Accounting for Unidentified Compounds
One of the concerns that has been raised by the public is
that, even with the lists described in the previous sections, there
may be a significant, number of unidentified compounds in the
emissions which will contribute to the overall risk from the
facility. While the risks associated with heavy metals are
believed to be adequately addressed directly, given the recommended
level of compound identification, the risks from unidentified
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DRAFT Revised April 22/ 1994
organic compounds could potentially be significant. Presented
below are two approaches for addressing those potential risks. OSW
recommends using the first option but solicits comment on the
second approach.
The first option assumes that the unidentified organic
compounds are similar in toxicity and chemical properties to those
of the identified organic compounds taken , as a whole, including
compounds from the PIC list and any other voluntarily identified
compounds that are toxic or that do not have toxicity data.
* " " ' . ' - .-,*'' i ' ' /' " '
Under this assumption, the total risks from the organic
compounds would be equal to the risks from the identified organic
compounds multiplied by the ratio of the mass of total organic
compounds to the mass of the identified organic compounds. This is
accomplished computationally by increasing the emission rate of
each of the identified organic compounds by the ratio of the
concentration of total organic compounds to the concentration of
all the identified organic compounds combined. Mathematically,
-this may be written as follows:
roc
t
i
where: ' ' .. . . - . . . '
Q- ad- = adjusted emission-rate of compound i
' Q1.' = emission rate of compound i
C- =stack concentration of compound i (carbon basis)
CTOC = stack concentration of total organic carbon
The risk assessment would then be conducted using the adjusted
(i.e., increased) emission rates for each of the identified organic
compounds. (Note: no adjustment is made to metals emissions.)
The second option would assume that 'all unidentified organic
compounds are carcinogens and have a carcinogenic potency that is
similar to the compounds on the PIC list. This option was.
developed to address the concern .that any voluntarily identified
compounds, beyond those on the PIC list, would tend to be primarily
noncarcinogens or low potency carcinogens.
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DRAFT - Revised April 22, 1994
Under this assumption, the total carcinogenic risk from the
organic compounds would be increased by adjusting the emissions of
each of the organic carcinogens on the PIC list as follows:
CTOC
Qcpitadj = QcPi ^
where: -
= adjusted emission rate of PIC list
carcinogenic compound i
Qcp± = emission rate of PIC list carcinogenic
compound i
Ccp^ = stack concentration of PIC list carcinogenic
compound i (carbon basis)
Cn_- = stack concentration of noncarcinogenic
compound j (carbon basis)
Ccnk = stack concentration of non-PIC list
carcinogenic compound k (carbon basis)
CTOC ~ stack concentration of total organic carbon
The risk assessment would then proceed using the adjusted
(i.e., increased) emissions for the organic carcinogens on the PIC
list and the measured (i.e., unadjusted) emissions for the organic
carcinogens not on the PIC list and the organic noncarcinogens.
The ratio for adjusting the emissions in the above equations
should be based on the .mass of carbon- This is because the
analytical methods typically used for measuring total organic
carbon are based on detection of the amount of carbon dioxide
released from thermally oxidizing the sample. The results may be
expressed on a carbon atom basis or some other basis (such as
propane). Therefore, the measured stack gas concentrations of the
organic compounds that are identified in the analysis must all be
converted to an equivalent carbon basis, as appropriate.
Total Organic Carbon Analysis . , ' '
A total organic carbon (TOC) analysis is necessary to account
for the portion of the organic emissions that are not specifically
identified and quant-tated. The permit writer should allow the
applicant the latitude to determine the method to be used to
measure TOC. At present, EPA cannot recommend a specific method.
Discussions with the Office of Research and Development are
underway which are intended to lead to the development of a
standard method. In the interim, the permit writer should require
the applicant to demonstrate that the method being used does detect
and measure a variety of organic compound types, such as the types
of organic compounds found on the PIC list. The method used should
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DRAFT Revised April 22, 1994
minimize any positive interference from the detection of carbon
dioxide and carbon monoxide. .".'
Quality Assurance :
In order to encourage as complete an identification of the
organic emissions as possible, the permit writer may require less
stringent data quality objectives for the organic compounds which
are not on the recommended PIC list.
For TOG the permit writer may want to consider establishing
.specific quality assurance.requirements on a case by case-basis to
ensure the, reliability of the data. ""'.'
Detection Limits
r~ * , ' - - '
For compounds on the PIC list which are not detected, the
permit writer should evaluate whether they are likely tos pose a
significant risk at concentrations near the detection limit. If
this is the case, or if the detection limit achieved during the
trial burn is significantly higher than can reasonably be achieved
using sound sampling and analysis procedures, then these compounds
should be included in the risk assessment at an assumed
concentration of 1/2 the detection limit. Other compounds which
are not detected need not be considered in the risk assessment.
GUIDANCE ON TRIAL BURNS .
See Attachment, B. ' '
APPLICATION OF DATA
See Attachment B. . :
. OTHER EMISSION SOURCES ' ':
The Draft Strategy is intended to address risks from
combustion units burning hazardous wastes. Therefore, the analysis
should ideally address air emissions from all sources that are_an
integral part of the combustion operation, including activities
such as storage, blending, and handling of wastes fed to th'e
combustion unit itself, as well as storage and handling of
combustion residues (e.g./ flyash, bottom-ash, and quench water)
generated by the combustion facility. For those faci? ities where.
these other activities are likely to contribute significant
emissions and for which enough information is available to analyze
their impact, the following approach is recommended.
"Fugitive" emissions generated from these on-site sources
include volatile organics from RCRA-permitted tanks, containers,
and related equipment (e.g., pumps, valves, and flanges) used in
the storage and handling of liquid hazardous waste and pumpable
solids, as well as fugitive dust from storage and handling of
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DRAFT Revised April 22, 1994
combustible solids and combustion residues in open tanks,
containers, waste piles, conveyers, and trucks. Fugitive emissions
of volatile organics from equipment leaks (pumps, seals, fittings,
etc.) can be estimated on the basis of "Protocol for Equipment Leak
Emission Estimates", Document No. EPA-453/R-93/026. Fugitive
emissions of volatile organics from storage tanks and containers
can be estimated using the methodology provided in "Hazardous Waste
TSDF: Background Information for Proposed RCRA Air Emission
Standards", Document No. EPA-450/3-89-023. These methods have been
adapted for spreadsheet calculations in th^ PC-based model,
CHEMDAT7, which is available from the OAQPS Technology Transfer
Network (TTN) electronic bulletin board. Fugitive dust emissions
from open waste piles and staging areas can be estimated using the
methodologies described in "Hazardous Waste TSDF - Fugitive
Particulate Matter Air Emissions Guidance Document", Document
No. EPA-450/3-89-019. Many of the calculations have been
computerized, as described in "User's Manual for the PM-10 Open
Fugitive Dust Source Computer Model Package", Document No.
EPA-450/3-90-010, and are available from the OAQPS TTN bulletin
board. Estimation of fugitive emissions using these methods
requires that estimates, be made or measurements be taken of the
concentration of chemical constituents (e.g., volatile organics,
semivolatile organics, and metals) in the wastes being used as feed
materials and in the combustion ash residuals.
Emissions from non-RCRA combustion units at the site
(e.g., power plants, etc.) and from other RCRA facilities in the
geographic area would not be directly included in the analysis but
would instead be considered as part of the background levels.
3. RISK CHARACTERIZATION ISSUES
Historically, human health risk assessments in the RCRA
program have focussed on high end individual risk or on bounding
estimates, such as the hypothetical "most exposed individual"
(MEI). In the context of permitting hazardous waste combustion
facilities pursuant to the EPA1s draft strategy, it is recommended
that risk assessors place primary emphasis on characterizing the
high end of the range of individual risks. .This is because it is
anticipated that high end individual risk will weigh heavily in
risk management decisions related to permitting.
SCREENING ESTIMATES
As a first step, screening estimates may be used to
demonstrate that risk from a particular combustion facility is
below a level of concern and that no further risk assessment
analysis is needed. Detailed guidance for conducting screening
analyses is provided in Attachment C.
The attached guidance, which was developed jointly by OSW and
OERR, is meant to serve as a "work book" for permit writers and
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DRAFT "~ . Revised April 22, 1994
others to use for - performing screening analyses at combustion
facilities burning hazardous wastes*, The guidance provided in the
primary guidance documents (i.e., the 1990 ORD report "Methodology
for Assessing Health Risks Associated with Indirect Exposures to
Combustor Emissions" and the November 10, 1993 Draft Addendum) has
been integrated and simplified for use in the screening procedure.
Also, the screening guidance provides recommendations for all--
parameter 'values thalb are required to perform the calculations,
except where site-specific values are recommended. .
General Approach . . ,
'.- The purpose of the screening guidance is to ^enable permit
writers to make conservative yet reasonable estimates of ,the
high-end individual risks from routine facility: emissions. The
objective is to approximate the high end .risk that would be
calculated,in a site-specific assessment if "high risk" activity
patterns occur at the locations of the maximum media
concentrations. However, a number of simplifications have been
made which in all likelihood, will ensure that the screening
estimates exceed the corresponding site-specific estimates. (For
example, maximum deposition~to soils and vegetation are assumed to
occur at the same location as the maximum ground-level air
concentrations. Also, the algorithms have been simplified by
eliminating a number of loss coefficients, many of which would
ordinarily have to be calculated; loss coefficients have been
retained only where .t.heir. inclusion is thought to be of particular
significance. In addition, for the purpose of modeling atmospheric
.dispersion and deposition, vapor phase emissions are assumed to
disperse and deposit the same as particle phase emissions.) f
The screening guidance addresses the major, pathways of
potential human exposure, both direct and indirect, although the
detailed procedures provided in the attached guidance focus on^what'
are generally believed to be the most significant indirect
Exposures such as ingestion of beef, milk, fish, and vegetables.
The screening guidance identifies which indirect exposure pathways
are important for what constituents, as determined by the physical
and chemical properties of the constituents. :The screening
guidance recommends that maximum or near maximum estimates of media
concentrations be used (i.e., concentrations in air, soils, and
surface waters), even if they occur at different locations. The
screening guidance recommends that the activity patterns ,that pose
the highest risk (i.e., subsistence farming and fishing)' be assumed
to occur at the point of maximum concentration, unless
site-specific information is available which clearly rules out
these activities. In such cases, the guidance recommends that
other potentially high risk activity patterns be evaluated at the
point of maximum concentration (e.g., eating homegrown vegetables)
and that subsistence activities be evaluated at alternative
; locations where such activities could potentially occur. For each
pathway and activity pattern, the screening procedure uses a
combination of high end and central tendency values, for the
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DRAFT . Revised April 22, 1994
* .
remaining parameters (other than media concentrations) to yield
reasonable maximum estimates of exposure.
Constituents
For indirect exposures, the screening guidance focuses on a
subset of constituents which have been judged to be of the greatest
concern by routes of exposure other than direct inhalation alone.
A multiple-pathway evaluation which emphasized food chain exposures
was conducted for 105 compounds on the PIC list. Factors that were
considered in choosing an appropriate subset to address in the
indirect exposure screening guidance included the importance of
indirect exposure pathways (relative to the direct inhalation
pathway) and the relative toxicity of the compound. OSW. is
currently evaluating the remaining compounds on the PIC list to
determine whether additional compounds, should be included in the
screening guidance.
The subset of constituents that was selected for inclusion in
the guidance for assessing indirect exposures is made up of
dioxin-like compounds (PCDD's and PCDF's), polycyclic aromatic
hydrocarbons (PAH's), polychlorinated biphenyls (PCB's), and
metals. Also included are selected chlorophenols, chlorinated
benzenes, nitroaromatics, and phthalates. These compounds are
among those that are most frequently detected during stack testing
of combustion devices. , ,
/
Other constituents identified in the stack emissions that are
present at levels of concern through indirect exposure routes
should also be included in the screening analysis. As indicated,
OSW is evaluating additional compounds for possible inclusion in
the screening guidance.' For compounds which are identified in
stack gases but are not now addressed in the screening guidance,
the Regions may want to contact OSW for assistance in evaluating
these compounds and/or obtaining the relevant physical and chemical
properties data. Also, as the PIC identification guidance (as
discussed in Section 2, Emission Issues) begins to be implemented,
the Regions are encouraged to inform OSW of the magnitude and
frequency at which the various compounds are being found in stack
gases. Such information will enable OSW to evaluate with greater
confidence what additional constituents may need to be addressed in
future revisions to the guidance.
For direct exposures, the screening analysis should includ,
all constituents for which data are, available (i.e., data on
emissions and information on toxicologic criteria or benchmarks).
The April 15, 1994 draft screening guidance, which includes four metals
(arsenic, beryllium, .lead, and mercury), will be revised to include eight
additional metals which are on the PIC list (antimony, barium, cadmium, chromium,
nickel, selenium, silver, and thallium). .
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DRAFT ^ Revised April 22, 1994
Given the diverse mixture of constituents to which individuals
may be exposed from combustion sources, a screening analysis should
consider additivity of both constituents and pathways, -***£E£
below in the sections "COMBINING CONSTITUENTS" and "COMBINING
PATHWAYS" and in the screening guidance. It is important to
include the significant constituents arid pathways in the screening
analysis in order to retain the conservatism necessary for
developing appropriate screening estimates.
Although it is anticipated that site-specific land use datai
will not generally be .needed to develop screening estimates, thj
screening guidance does recommend that some site-specific data be
used This is the case for much of the input data required for the
air dispersion and deposition model (currently recommended as
COMPDEP), due to the comple* interactions among stack related
parameters, terrain, and meteorological conditions. Here; data
avaiTabiUty should not be an issue:' values for stack parameters
should be available for any facility seeking a RCRA permit; .actual
terrain data are readily available for virtually all' locations; and
Sourly meteorological data are available for numerous sites around -
the country. The use of actual terrain and meteorological data is
regarded as standard practice for the application of air dispersion
models for most air pathway analyses involving^the use ff. long-term
(e.g., annual) average ambient air concentrations. .Although the
effort' required to process these data is not trivial, standard
procedures and software are available for doing so and are widely
used. Sources from which these data may be obtained are identified
in the screening guidance.
/ _ _ , -
' '. The screening -" guidance also recommends that certain
site-specific data be used for surface water pathways, in
particular the size and location of -the watershed or waterbody and,
for rivers and streams, the average annual flow. Such data are
readily available and should be used; in .certain instances,
however, conservative default values are provided if needed.
Fugitive Emissions and Upsets
Fugitive emissions and upset emissions should be included^in
the screening analysis. Although upsets are not generally expected
tfincrtasestTck Emissions by more than .a factor of two over the
life of the facility, upset emissions should be estimated for the
particular facility based on the operating "history of the facility
or similar faciaities.. Fugitive emissions should be estimated
based on the types of wastes the facility will be burning (See
the discussion of "Other Emission Sources" under Section 2,
"Emissions Issues") ;
Since fugitive emissions have characteristics that; are
different from those of stack emissions, dispersion of fugitive
emissions should be modeled separately, with the plume impacts
being added at the receptor point. A number of dispersion models
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DRAFT Revised April 22, 1994
can be used for this purpose, including the FDM and ISC2 models,
models which are available on the OAQPS TTN bulletin board.
Ecological Effects
Given the EPA's commitment to the protection of ecosystems, it
is also expected that as part of the screening analysis an
evaluation should be conducted of the potential for ecological
impacts to the extent feasible. (Although this issue arises in
both screening and detailed or site-specific assessments, it is
discussed here.) The ecological assessment should include
identifying critical ecological resources to be protected from
reduction, degradation, or loss in quantity, quality or use,
including critical fish and wildlife habitat and the presence of
endangered species. Also, the ecological assessment should include
an evaluation of whether the impacts of the.combustion facility on
ambient surface water concentrations of toxic constituents are
likely to cause exceedances of State water quality standards.
HIGH END INDIVIDUAL EXPOSURE
If the screening analysis indicates that a more detailed,
site-specific risk assessment is needed, it should include, a
description of the high end of the distribution of individual
exposure(s). High end exposure(s) are plausible estimates 'of
individual exposure(s) for those persons at the upper end of the
distribution. The intent of this descriptor is to convey estimates
of exposure in the upper range of the distribution, but to avoid
estimates which are beyond or above the true distribution.
Conceptually, high end exposure(s) means exposure(s) above the
90th percentile of the population distribution, but not higher than
the individual in the population who has the highest exposure.
The Draft Addendum describes an approach for estimating, the
distribution of exposures across the population in the study area
through a combination of concentration isopleths and information on
activity patterns (location of farms, residential areas, etc.).
This approach provides exposure estimates for population subgroups
(farmers, school children, etc.) within each of the isopleths, and
these estimates can be combined to yield a" general population
distribution. The high end individual exposure can then be
determined by selecting within the most exposed 10 percent of the
distribution.
This approach will require that a substantial amount of
information be collected on locations and activity patterns for the
whole population of concern in the study area. An alternative
approach would be to identify those populations in areas with
relatively high concentrations and high risk activity patterns and
define these as the high end of the distribution. This alternative
"Guidance for Risk Assessment", Risk Assessment Council, November 1991.
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DRAFT = Revised April 22, 1994
may require some iterative analysis, particularly since high risk
activity patterns can vary depending on the constituent. -However,
this approach could require collection of substantially less
information. : . ,
Once a population of concern has been identified, one can
either set all exposure parameters such as consumption rates to
central tendency values (if 'this population is relatively small) or
else high end exposures within that population can be estimated by
identifying the most . sensitive parameters that determine the
average daily dose and setting the values of one or a few of these
to their high end values while leaving all other parameters at
their "typical" values. However, combinations of parameter values
that are highly unlikely to occur at the same time should be
excluded. Generally speaking, parameters that are known to be
highly correlated should be varied together. Whether the upper end
or the lower end of the distribution of the parameter is used
depends on whether the - parameter has a. directly,proportional, or
inversely proportional relationship to risk. Sensitivity analysis
should be performed to support the selection of the most sensitive
parameters for the various constituents and pathways.'
In setting the values of the most sensitive parameters for use
in estimating the high end exposure, it is recommended that values
at or above the 90th percentile be used (or, conversely, at or
below the 10th percentile) If only a relatively few data points
are available, the maximum or near-maximum value should be used
(or, conversely, the minimum or near-minimum value).
COMBINING CONSTITUENTS . ' ' ' ' . ^. ,
, Generally speaking, the risks to an individual exposed to a
mixture of carcinogens 'should be combined by adding ^ the
constituent-specific risks, unless synergistic or, antagonistic^
interactions are known to occur for the specific mixture.
However, for systemic toxicants, estimating a hazard index_for a
mixture is generally appropriate only if theg constituents induce
the same effect by similar modes of action. . Because different
effects occur for the same chemical at different dosages, and
because biochemical mechanisms are infrequently known or
understood, it is suggested that hazard indices for mixtures be
estimated only if, at a minimum, the RfDs of the. individual
3 Ibid.
4 "The Risk Assessment Guidelines of 1986", Office of Health and
Environmental Assessment, August 1987., ., -
5 Ibid.
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components are all based on effects in the same target organ.* It
should be noted that, since many carcinogens also exhibit systemic
effects, carcinogens should be included for consideration when
non-cancer individual risks from chemical mixtures are being
evaluated.
COMBINING PATHWAYS -
' ' ' ' > , .
When estimating individual daily doses, exposures from
different pathways should be added for each route of exposure
(i.e., oral, dermal, or inhalation) if there is a reasonable
expectation that the same individuals are exposed.
t - .
For carcinogens, exposures can be added across direct and
indirect pathways if the constituent is a carcinogen through both
oral and inhalation routes. For non-carcinogens, it is appropriate
to add oral and inhalation exposures only if there is information
to indicate that the oral reference dose and the inhalation
reference concentration are based on the same effect. Generally,
dermal exposures can be combined with oral exposures.
When combining exposures, it is important to consider whether
the same individual is likely to be ;exposed through each of the
exposure pathways that are being added.
EXPOSURE DURATION
The duration of exposure should take into account both the
expected operational life of the facility and the time period of
residence that is discussed in the guidance. For many exposure
pathways, exposures may continue after the facility has ceased
operations, due to continued cycling of contamination in and
between biota, soils, and sediments. Generally speaking, exposure
durations should represent less-than-lifetime exposures, unless it
is reasonable to expect that individuals will be exposed for a
lifetime. Estimates of the likely duration of exposure via a given
exposure pathway should be made wherever possible. Local census
data and, for unusual situations, limited site-specific surveys can
help establish the likely durations of individual exposures.
4. RISK MANAGEMENT ISSUES
LAND USE ' '
The risk assessment should consider both current land use and
ways in which the land surrounding a combustion unit are reasonably
6
"Risk Assessment Guidance for Superfund Volume I Human Health Evaluation
Manual (Part A)", Office of Emergency and Remedial Response, December 1989.
7 Ibid.
14
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DRAFT Revised April 22, 1994
likely to be used so that the appropriate exposure pathways,
potentially exposed populations, 'exposure parameters, and equations
can be used to estimate acceptable emission limitations. To
determine reasonably expected land uses, risk assessors should rely
on a combination of available information and best professional
judgment. Several factors to be considered for determining
reasonably expected land use include: projected land use based on
recent trends, changes in population growth and population density
near the combustion unit, and restricted land uses because of local
zoning laws. ' , "
ACCEPTABLE TARGET LEVEL ' > ' ' '
To ensure protection of human health from emissions of toxic
constituents, the total incremental risk from the high-end
individual exposure to carcinogenic constituents should not
exceed 10 . For systemic toxicants, the hazard quotient (e.g., the
ratio of the total daily oral intake to the reference dose) for the
constituent or, when appropriate, the mixture should be less
than 0.25. In the case of lead, for which there is no reference
dose, direct comparison with media-specific health based levels is
.suggested, after adjusting for background level|; specifically,
values of 100 mg/kg for soils and 0.2 M9/m for air are
recommended. (Note: See the discussions on "COMBINING CONSTITUENTS"
and "COMBINING PATHWAYS" for more specific guidance.)
The selection of these levels fas opposed to, for example, an
incremental cancer risk level of 10" and a hazard quotient of 1.0)
was done in part to ciccount for exposure to background levels _ of
contamination (including indirect exposures from other combustion
units) which should be considered as part^of the risk estimation
and decision-making process to set emission, levels at a combustion
Unit. The unit will not likely be the only source contributing to
exposures in the study area and to neglect other environmental
sources may overestimate an allowable emission level, leading to
unacceptable total risk to the public. In this case, background is
, defined as those exposures in drinking water, food, and air
attributable to sources other than the combustion unit(s) being
assessed.
If detailed information on background sources is available for
a particular area, the permit writer may choose to use this
information to develop an alternative approach for incorporating
background levels.
8 This approach is consistent with the approach taken in the Boiler and
Industrial Furnace Rule, 56 FR 7169 (February 21, 1991)., However, the way in
which cancer risk is estimated in this guidance differs from the BIF rule to more
closely follow Agency guidance. For example, in the'BIF rule carcinogenic metals.
and organic compounds are not aggregated, Group A and B carcinogens are not
aggregated with Group C carcinogens, and a hypothetical MEI' is estimated.
15
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DRAFT Revised April 22, 1994
NOTE; The results of any risk assessment which is
conducted pursuant to this guidance do not
replace the requirements of the BIF rules at
40 CFR Part 266 Subpart H. Therefore,
allowable levels of metals emissions that are
derived from a risk assessment conducted
pursuant to this guidance should .be compared
to those determined under the BIF rule and the
more stringent levels rhould be used to
establish the permit limits. However, for
incinerators, allowable levels that are
derived from a risk assessment conducted
pursuant to this guidance should be used to
establish the permit limits, as applied under
Omnibus authority.
16
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DRAFT
Attachment A
April 15, 1994
Table 1. Chemicals Recommended for Identification
CAS Number
75-07-0
98-86-2
107-02-8
107-13-1
7440-36-0
7440-38-2
7440-39-3
71-43-2
56-55-3
205-99-2
50-32-8
96-07-7
100-44-7
7440-41-7
92-52-4
111-91-1
117-81-7
590-60-2
Chemical Name
1
i Acetaldehyde
Acetophenone
Acrolein
Acrylonitrile
Anthracene
Antimony
Arsenic
Barium
Benzaldehyde
Benzene
Behzo(a)anthracene
Benzo(b)fluoranthene
Benzo(j)fluoranthene
Benzo(k)fluoranthene
Benzo(a)pyrene
Benzo(e)pyrene
Benzo(g,h)perylene
Benzotrichloride
Benzyl chloride
Beryllium
Biphenyl
Bis(2-chlofoethoxy)methane
Bis(2-ethylhexyl)phthalate
Brornochloromethane
Brornodichloromethahe
Brornoethene
A-l
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DRAFT
April 15, 1994
Table 1. Chemicals Recommended for Identification
CAS Number | Chemical Name
75-25-2
74-83-9
106-99-0
85-66-7
7440-43-9
56-23-5
57-74-9
532-27-4
106-47-8
106-90-7
510-15-6
67-66-3
74-87-3
91-58-7
95-57-8
75-29-6
7440-47-3
218-01-9
1319-77-3
1319-77-3
1319-77-3
4170-30-3
94-75-7
3547-04-4
53-70-3
96-12-8
84-74-2
95-50-1
Bromoform
Bromomethane
1 ,3-Butadiene '
Butylbenzyl phthalate
Cadmium
Carbon tetrachloride
Chlordane
2-Chloroacetophenone
p-Chloroaniline
Chlorobenzene
Chlorobenzilate
Chloroform
Chloromethane
B-Chloronaphthalene
2-Chlorophenol
2-Chloropropane
Chromium
Chrysene
m-Cresol
o-Cresol
p-Cresol
Crotonaldehyde .
2,4-D
DDE
Dibenz(a,h)anthracene
1 ,2-Dibromo-3-chloropropane
Dibutyl phthalate '
1 ,3-Dichlorobenzene
A-2
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DRAFT
April 15, 1994
Table 1. Chemicals Recommended for Identification
CAS Number
95-50-1
106-46-7 ,
764-41-0
764-41-0
75-71-8
107-06-2
75-35-4
156-80-5
120-83-2
542-75-6
542-75-6
84-66-2
105-67-9
131-11-3
119-90-4
99-65-0
100-29-4
121-14-2
606-20-2
117-84-0 ,
1 23-39-1
100-41-4
106-93-4
75-21-8
96-45-7
75-34-3
206-44-0
Chemical Name
1 ,2rDichlorobenzene ,
1 ,4-Dichldrobenzene
(cis) 1 ,4-pichloro-2-butene
(trans) 1 ,4-Dichloro-2-butene ;
Dichlorodifluorornethahe
1 ,2-Dichloroethane
1 , 1 -Dichloroethylene
(trans) 1,2-dichloroethylene
2,4:Dichlorophenol :
(cis)1 ,3-DichIoropropene
(trans) 1 ,3-Dichloropropene
Diethyl phthalate
2,4-Dimethylphenol
Dimethyl phthalate
3,3.'-Dimethoxybenzidine
i,3-Dinitrobenzene -
o-Dinitrobenzene
p-Dinitrobenzene
2,4-Dinitrotoluene
2,6-Dinitrotoluene
Difn)octyl phthlate
1,4-Dioxane , ,
Ethylbenzene - ,
Ethylene dibromide .-',''-
Ethylene oxide
Ethylene thiourea
Ethylidene dichloride
Fluoranthene ...'.'
A-3
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DRAFT
April 15, 1994
Table 1. Chemicals Recommended for Identification
CAS Number
50-00-0
76-44-8
1 1 8-74-1
87-68-3
319-84-6
319-85-7
77-47-4
67-72-1
70-30-4
110-54-3
193-39-5
7439-2-1
123-33-1
7440-97-6
72-43-5
71-55-6
106-87-2
Chemical Name
Formaldehyde
1 , 2,3,4,6,7, 8-Heptachlorodibenzofuran
1,2,3,4,7,8,9-Heptachlorodibenzofuran
Heptachlor
1,2,3,7,8,9-Hexachlorodibenzo(p)dioxin
. 1 ,2,3,4,7,8-Hexachorodibenzofuran
1 ,2,3,6,7,8-Hexachlorodibenzofuran
1 ,2,3,7,8,9-Hexachlorodibenzofuran
2,3,4,6,7,8-Hexachlorodibenzofuran
Hexachlorobenzene
Hexachlorobutadiene
a-Hexachlorocyclohexane
B-Hexachlorocyclohexane
r-Hexachlorocyclohexane
Hexachlorocyclopentadiene
Hexachloroethane
Hexachlorophene
n-Hexane
Indenod ,2,3-cd)pyrene
Lead
Maleic hydrazide
Mercury
Methoxychlor
Methyl chloroform
Methylcyclohexane
A-4
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DRAFT
AprU 15, 1994
Table 1. Chemical;, Recommended for Identification
CAS Number
78-93-3
74-95-3
75-09-2
91-20-3 '
88-74-4
96-95-3
100-02-7
924-1 6-3
608-93-5
82-68-8
87-86-5
1 08-95-2
75-44-5
1336-36-3
123-36-6
78-87-5
91-22-5
106-51-4
94-59-7
7440-22-4 .
1 00-42-5
Chemical Name .
r . . i
Methyl ethyl ketone -
Methylene bromide
Methylene chloride
Naphthalene _
Nickel
o-Nitroaniline
Nitrobenzene
4-Nitrophenol
N-Nitroso di-n:butylamine
1 - /.
Octachlorodibenzo{p)dioxin . ,
Octachlorodibenzofuran / .
l^jS^.S-PentachlorodibenzotpJdioxin
1,2,3,7,8-Pentachlorodibenzofuran .
2,3,4,7,8-Peritachlorodibenzofuran
Pentachlorobenzene ;
Pentachloronitrobenzene
Pentachlorophenol
Phenol
Phosgene
Polychlorinated biphenyls (209 congeners)
Propionaldehyde
Propylene dichloride
Quinoline . .
Quinone ,
Safrole (5-(2-Propenyl)-1 ,3-benzodioxole)
Selenium
Silver
Styrene -
A-5
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DRAFT
April 15, 1994
Table 1. Chemicals Recommended for Identification
CAS Number
95-94-3
1746-01-6
630-20-6
79-34-5
127-18-4
58-90-21
7440-28-0
106-88-3
95-53-4
106-49-0
120-82-1
79-00-5
79-01-6
75-69-4
95-95-4
88-06-2
96-18-4
76-13-1
1 08-05-4
75-01-4
75-35-4
1 330-20-7
1330-20-7
1330-20-7
Chemical Name
1 ,2,4,5-Tetrachlorobenzene
2,3,7,8-Tetrachlorodibenzo(p)dioxin
2,3,7,8-TetrachIorodibenzofuran
1 , 1 , 1 ,2-Tetrachloroethane
1 , 1 ,2,2-Tetrachloroethane
Tetrachloroethylene
2,3,4,6-Tetrachlorophenol
Thallium
Toluene
o-Toluidine
p-Toluidine
1 ,2,4-Trichlorobenzene
1 , 1 ,2-TrichIoroethane
Trichloroethylene
Trichlorofluortimethane
2,4,5-Trichlorophenol
2,4,6-Trichlorophenol
1 ,2,3-Trichloropropane
1 ,1 ,2-Trichloro-1 ,2,2-trifluoroethane
Vinyl acetate
Vinyl chloride
Vinylidine chloride
m-Dimethyl benzene (xylene) "
o-Dimethyl benzene (xylene)
p-Dimethyl benzene (xylene)
A-6
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DRAFT
.April'15/1994
Table 2. Chemicals for Potential Identification
CAS Number 1 Chemical Name
\ .
"
Ammonia
Aniline
o-Anisidine
Azbbenzene
Bis (2-cnIoroethyl) ether
Bis (chloromethyl) ether
Carbon disulfide
Chlorocyclopentadiene .
Cumene ,
Cyanogen
Cyanogen bromide
Cyanogen chloride
2-Cyclohexyl-4,6-dinitropenol ,
Dibenzo(a,e)fluorarithene
Dibenzo(a,h)flouranthene , , .
3,3-Dichlorobenzidine
Dichloroisopropyl ether .
Dichlbromethyl ether
Dichloropentadiene
Dimethyl aminoazobenzene '.-
1 ,2-Dimethylhydrazine ' .
Dimethylnitrosamine
Dimethyl sulfate
4,6-Dinitro-o-cresol
2,4-Dinitrophenol
Diphenylamine
1 ,2-Diphenylhydrazine
Di-n-propylnitrosamine
A-7
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DRAFT
April 15, 1994
Table 2. Chemicals for Potential Identification
CAS Number
Chemical Name
Endothall
Epichlorohydrin
2-EthoxyethanoI
Ethyl carbamate _
Ethyl chloride
Ethyl methacryiate
Ethyl methanesulfonate
Ethylene glycol
Ethylene glycol monobutyl ether
Ethylene glycol monethyl ether
Ethylene glycol monoethyl ether acetate
Formic acid .
Furfural, ,
Glycidylaaldehyde
Hexamethylene-1 ,5-diisocyanate
Malononitrile
Methacrylonitrile
2-Methoxyethanol
Methyl isobutyl ketone
Methyl isocyanate
Methyl mercury
Methyl styrene (mixed isomers)
Methyl tert-butyl ether
4,4-Methylenedianiline
Phthalic anhydride
Pronamide
1 ,3-Propane sultone
Propargyl alqohol
A-8
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DRAFT
April 15, 1994
Table '2. Chemicals for Potential Identification
«'
Chemical
'.'... ' ; '
\ . ' .
Name
Propylene glycol monomethyl ether ,
Pyridine
Strychnine
Toluene-2,6-diamif»e
2,4-Toluene diisocyante
2,2,4-Trimethylpentane
1,3,5-Trinitrobenzene .
A-9
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DRAFT , ._ . 5/2/94
Attachment B : ' '
GUIDANCE ON TRIAL BURNS
i . ' .'..-,.. .
Historically, RCRA trial burns have been conducted in order
for hazardous waste combustion facilities to demonstrate
compliance with regulatory performance standards and other
emission limits. Applicable emission standards included minimum
destruction and removal efficiency (ORE) for selected principal
organic hazardous constituents (POHCs), as well as risk-based
mass emission limits for toxic metals. Since it is not possible
to conduct stack emissions monitoring for specific^organic and^
metal constituents on a continuous basis, the conditions at which
the combustion device operated during the trial burn Were
included in the permit as conditions for operation. ,
: Implementation of the Draft Waste Minimization and
Combustion Strategy (hereafter referred ,to as the Draft Strategy)
expands the objective and use of data generated from trial burns.
Under the Draft strategy, comprehensive emissions data must be
generated during the trial burn for incorporation into multi-end
point risk assessments.
The principal new trial burn information which must be
generated to support multi-endpoint risk assessments is stack
emissions data on a much wider range of organic constituents.
.These organic constituents are loosely referred to as products of
incomplete combustion (PICs). There is concern that PIC
emissions, including dioxin/furan compounds', may. significantly
contribute to the overall risk posed by hazardous waste
combustion facilities. In general, the available information
databa,se is limited relative to the waste composition and unit
operating conditions on PIC speciation and concentration. Prior
evaluations have suggested that limiting- stack carbon monoxide to
100 ppmv (corrected to 7% oxygen) arid/or hydrocarbon (HC)
concentration to less than 20 ppmv (as propane, measured hot,
corrected to 7% oxygen) will adequately control the inhalation
risk from PICs. However, with respect to risk from indirect
exposure, there is not sufficient information currently available
to verify that the CO and HC emission,limits (as identified
above) are sufficiently protective. Consequently, it will be
necessary to further speciate PICs and quantify individual PIC
emission rates as part of the trial burn process at each
facility.
" ' ."""'- . B-l "' . , . ..',',.'
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DRAFT 5/2/94
Metals emissions data is another important consideration.
Metals emissions determinations should be expanded to generate
data on metals which can be important for multi-pathway risk
assessments (i.e., copper, aluminum, nickel, selenium, and
zinc ) in addition to the ten toxic metals identified in the
boiler/industrial furnace regulation which are of concern from
the inhalation pathway. Metals speciatioh information is also
desirable for risk assessments. Stack test data typically
provides information on the total mass emission rate of a
.particular metal, but not on the chemical speciation of that
metal. Unfortunately, for the majority of metals, this issue
cannot be addressed at this time since, with a few exceptions,
analytical methods to accomplish metals speciation are not yet
available. As analytical methods become available, permit
writers may consider adding metals speciation determinations to
trial burns. ,
The current "Guidance on Setting Permit Conditions and
Reporting Trial Burn Results" addresses trial burn planning for
determining compliance with DRE and other regulatory performance
standards. Similarly, the boiler/industrial furnace regulations
and accompanying guidance provide trial burn planning guidelines
for determining compliance with risk-based metals emissions
limits. Therefore, this guidance is intended as a supplement to
the previous guidance to more specifically address generation of
organic PIC emissions data during trial burns for use in multi-
end point risk assessments.
TRIAL BURN CONDITIONS NEEDED TO GENERATE PIC EMISSIONS DATA FOR
USE IN RISK ASSESSMENTS
A brief review of definitions and current guidance is
appropriate in order to provide a framework for the topics
contained in this guidance. First, there has been historic
confusion relative to the terms POHCs, PICs, and organics. For
the current guidance, use of the term "PIC" encompasses any
organic species emitted from the stack, regardless of the origin
of the compound. Risk assessments are generally concerned with
the health risks posed by emissions from the facility. It makes
no difference with respect to risk if the organic was formed from
a compound specified as a POHC, if it is a partial oxidation
product of the POHC, or if it formed from other materials added
to the combustion device. However, from a trial burn
perspective, it may be beneficial for the permit, writer to
consider three sub-categories of the broad grouping of PICs.
These include:
Some of these metals, such as copper and aluminum, may not
have a significant < impact directly on the risk assessment, but may
affect the formation of other toxic compounds such as
dioxins/furans. ,
B-2 ' '" '
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DRAFT / 5/2/94
Unburned organics originally present in the waste feed,
but not necessarily selected as "POHCs" for
determination of DRE.
Other PICS (i.e., from partial destruction and/or
recombination reactions), and
. Other trace toxic .organics such as dioxins and
.furans that may be formed downstream of the combustion
chamber by low temperature reactions involving fly
ash.- ... . : . . - -','
The first of these three groups is included since failure to ;
destroy any organic included in the waste feed can contribute to
the overall risk posed by the facility. The second group
includes the wide range of compounds that are traditionally
thought of as PICs. The final group, which includes dioxins and
furans, is actually a sub group of the earlier categories but has
been singled out because these compounds are expected^to have a
profound influence on risk assessment. They are also singled out
because they are formed under conditions that must be
specifically considered in planning trial burns.
Also, a brief review of current trial burn planning guidance
is helpful. As mentioned previously, trial burn operating
conditions have historically played an important role in assuring
ongoing performance with DRE and metals performance standards.
Key "control parameters" were identified before the trial burn.
As part of the trial burn planning process, waste feed and
combustion device operating conditions were selected in order to
determine the operating extremities for each of^the control
parameters (i.e., maximum chloride feed rate, minimum
temperature, etc.). Permit limits were placed on each of the
control parameters based on measurements taken during the trial
burn. These "permitted operating limits" defined the range of
acceptable operation for post-trial burn operation. As long as
the combustion device was operated within the permitted range, it
was assumed to be meeting the emissions performance standards.
In order to implement the Draft Strategy, the data needs for
the risk assessment must also be'addressed as part of trial burn
planning. From a risk assessment standpoint, there is support
for measuring PIC emissions during normal operation of the
combustion device (instead of the extreme ranges which have '5een
'required during DRE and metals tests). The emissions during
normal operation may relate more directly to the risk posed by
the combustion device over its operating life. However, we are
not aware of any mechanism to set permit conditions to assure
that the average emissions posed by the "normal" operation,
tested during the trial burn, will not be exceeded. Nor is it
possible to continuously monitor the emissions of toxic
pollutants used in the risk assessment. Therefore, this guidance
generally recommends that emissions data for use in the risk
'. " : B-3 . ,..''-;- '
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DRAFT 5/2/94
assessment be generated based on the "permitted operating limits"
developed during the trial burn- for PICs, similar to the approach
that has been historically used for DRE and metals trial burns.
One challenge relative to the "permitted operating limits"
PIC condition approach is that there is limited information
available on how waste feed and unit operations impact speciation
and concentration of the wide range of PICs that must be
accounted for in the risk assessments. Traditionally, trial
burns have included special tests for: (1) metals where the
system operating temperature is maximized; and (2) for POHC
emissions, where system temperatures are minimized. There is a
logical argument which suggests that the trial burn conditions
for POHC emissions will also result in significant PIC emissions,
particularly if PICs are specifically considered in selecting
trial burn.feeds. However, available data does not show that
this argument is necessarily valid for dioxins and furans, which
are critically important PICs. For dioxins and furans, catalytic
formation seems to be more dependent on the higher air pollution
control device temperatures that are typically seen during a
worst-case metals test. Therefore, to reflect the range of
operating conditions that could influence PIC emissions, this
guidance recommends that PIC emissions be quantified during both
the minimum temperature POHC test(s) and the maximum temperature
metals test(s). In planning these tests, consideration must be
given to the additional control parameters identified in this
guidance which could potentially influence PIC generation.
Characteristics of the waste burned, the combustion
technology employed, and the flue gas cleaning equipment used are
all expected to influence the types and amount of PICs generated
and emitted. At this time, the major items of concern with
respect to worst-case PIC generation conditions during trial
burns are listed following this section. For each item, general
recommendations are provided regarding whether the specific
parameter is best demonstrated during the low temperature POHC
test(s) or the high temperature metals test(s). In addition, the
guidance suggests which parameters should be specifically
translated into final permit conditions.
As a cautionary note, the permit writer must keep in mind
that the owner/operator of the facility will generally attempt to
get the device permitted for the broadest band of operating
conditions (i.e., the Tiost extreme operating conditions).
Therefore, the permit writer must take great care in reviewing
the trial burn to assure that he/she will be able to set
appropriate performance (permit) standards based on the trial
burn, and, that the trial burn itself does not pose an imminent
hazard to human health or the environment (as specified in
Subpart 260.62 of 40CFR). In addition, he should be reasonably
confident that the trial burn will not result in the violation of
applicable standards such as DRE and CO.
B-4
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DRAFT *- ; '" .' 5/2/94
To assure that there is'no problems during the trial burn
the permit writer must have some assurance that the device is , .
operated under Good Operating Conditions (GOC). Due to the
complexity and number of different types of devices involved this
document does not attempt to fully define GOC. However, the
permit writer should use his experience and engineering judgement
in making the determination as well as documents such as the
draft "Combustion Emissions 'Technical Resource Document"
(CETRED). CETRED defines Best Operating Practices (BOP) for some
devices. The permit writer may endeavor (and is encouraged) to
implement BOP as defined in CETRED, if applicable, even if he/she
is able to determine GOC by other means. If the permit writer is
left with a particularly difficult determination, he/she should
feel free to call on the resources of the Waste Combustion Permit
Writers' Work Group. ,
WASTE FEED CONDITIONS _
Test data from hazardous waste and other combustion
processes show many of the same PICs are formed regardless of 1:he
type of waste or fuel burned. In other instances, PIC
characteristics;may be directly related tp the waste chemical
composition or,physical properties. To best reflect PICs which
might be directly related to site-specific waste composition,
trial burns should utilize reasonable worst-case "real" wastes
(which may be spiked with POHCs or other constituents) instead of
surrogate wastes .(wastes synthesized from mixtures of .pure
compounds). Representative wastes should be selected based upon
a review of the wastes handled at the particular facility. This
issue is discussed in more detail under SELECTION OF REAL WASTES
BASED ON QUANTITY AND TOXICITY. Considering site-to-site
variations in both the "waste composition and technologies
employed, realistic conditions to demonstrate maximum PIC
emissions must be selected with an understanding of factors which
influence the formation and emission control of PICs.
Major PICs of concern include chlorinated (or brominated)
compounds such as dibenzo-p-dioxins, chlorinated dibenzofurans,
chlorobenze'nes, chlorophenols, polychlorinated biphenyls (PCBs) ;
polycyclic aromatic hydrocarbons (PAHs); and nitrogenated PAHs.
PIC formation may result from poor combustion conditions in
the high temperature, regions of the combustor. PICs may also be_
formed (or transformed) through low temperature reactions in
system components downstream of the combustor. Poor combustion
can result from a variety of factors including uneven feed
conditions, inadequate combustion temperatures or residence
times, low or excessive amounts of combustion air, and .inadequate
mixing. In the case of highly chlorinated wastes, PIC formation
can also result from chlorine or other halogen combustion
B-5
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DRAFT 5/2/94
reactions which reduce the amount of OH radicals necessary for
complete destruction of hydrocarbons .
Low temperature PIC formation and transformation downstream
of the combustor is extremely important from a risk assessment
perspective. Data from municipal waste combustion systems,
medical waste incinerators, and cement kilns indicate that the
majority of dioxins and furans emitted from these facilities are
generally created in the low temperature regions provided by
particulate control devices. This low temperature formation of
dioxin and related chloro-organic compounds (and possibly bromo-
organic compounds) involve fly ash catalyzed reactions of _
halogens with undestroyed organic material from the furnace .
In some cases, some organics in the stack gases may originate in
raw materials other than the hazardous waste which are fed to the
furnace. Metals which are "thought to promote these reactions
include copper, iron, zinc, nickel, and aluminum. The source of
organic material -for these low temperature reactions can either
be from (1) specific precursor compounds (chlorobenzenes,
chlorophenols, etc.,) which escape destruction in the high
temperature regions of the combustor or (2) organic decomposition
products originating from low temperature oxidization of the
carbon in fly ash. The rate of PIC formation is dependent upon
the amount of undestroyed organics, the amount and form of
halogens (amount of dioxin precursors present), the amount and
composition of fly ash, the flue gas composition, arid the APCD
temperature. Under some conditions, large amounts of chlorinated
organics can be created in particulate matter collection devices.
The following list of waste/feed extremities should be
considered in the development of the trial burn plan. The
extremities in this discussion refer to the maximum or minimum
trial burn condition or potential permit condition, as
applicable. Although they are referred to as extremities, they
should always represent good operating practice:
1. Variability of Batched-Charaed Waste Teed Higher
levels of PICs are produced during combustion upsets. Upset
conditions may result from short term variations (i.e., less than
15 minutes) in the properties of fuel or waste being fed to the
combustor. As noted earlier, trial burn"tests for collecting PIC
risk assessment data should be conducted while the unit is
Wesbrook, C.K., Inhibition of Hydrogen Oxidation in Laminar
Flames and Detonations by Halogenated Compounds, Nineteenth
Symposium (International) on Combustion, The Combustion Institute,
1982, (pp.127-141). ,
3 In some cases, the organics in the stack gases may originate
in the raw materials fed to the furnace, especially in the case of
a cement kiln.
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RAFT . .. '; . ' '.' ..'....' " ....__"
burning waste that is representative of the wastes'normally
, burned at the facility. .This guidance is particularly important
for commercial .burners where the waste is received from many
sources and the feed is reasonably expected to be highly
variable. In these situations, there is concern that rapid
changes in, waste characteristics may disrupt the normal sequence
of oxidation reactions, such as with "puffing", and lead to
significant PIC release. Phenomena of this type may not be
revealed through testing unless the tests are carefully planned
to assure the material burned adequately characterizes the
reasonable worst case waste that could create such a phenomenon.
' . It is suggested that the permit writer carefully examine the
expected characteristics of waste to be burned at a facility and
assure the applicant develops a trial burn in which the unit is
fired with a sequence of waste that is representative of wastes
typically burned at the facility; If the unit is batch charged
(such as drum fed rotary kilns), individual charges should
present the incinerator with the most,challenge with respect to
parameters such as waste volatility, waste heating value,
moisture content, molecular weight, oxygen content, and halogen
content that are expected to be fed to the incinerator. Once
these parameters are/maximized (or minimized as in the case of O2
content), variations between the charges and their sequencing
should be minimized to increase the repeatability of the test
runs. This scenario is consistent with the "Guidance, oh Setting
Permit Conditions and Reporting Trial Burn Results" which
specifies the feeding of containers with the highest volatility
during the trial burn. The high moisture content requirement may
be in conflict with some of the other parameters such as
volatility and heating value. Therefore, it the moisture
content is higher than a nominal amount in containers
(approximately 5%), then the facility should consider another
test run with maximized moisture content.
If the trial burn waste or fuel is oxygenated, this oxygen
level should be considered as a floor when setting permit
conditions. Ideally, the incinerator and its control system will
be designed and operated to account for this type of variability.
If not, the shortcoming .will probably be reflected in higher PIC
emissions and higher indicated unit risks. These higher*PIC
emissions will be reflected in higher CO- and HC measurements as
well as low O2. If this situation is a problem the facility must
find ways- to reduce the waste variability'to minimize emissions
and upsets. In some cases, a hew test may be required or the
permit writer may consider other measures such as minimum excess
oxygen levels.
Permit limits should address the same parameters, as other
wastes as well batch size, frequency, heating value, and
container type (including thickness). ... ' .
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DRAFT 5/2/94
2. Wastes with a high content of halogens. A high halogen
content may locally deplete the available OH radicals which are
necessary for complete destruction of organics and may lead to
excessive amounts of PAHs or halogenated organics being formed.
Generally, these halogenated organics, which include dioxins and
furans, are the most toxic PICs. While this problem may be
associated with all types of combustors, liquid waste
incinerators operating with high halogen feed concentrations and
relatively low excess air levels may be particularly vulnerable.
Therefore, testing should be conducted using the highest levels
of halogens in the wastes and auxiliary fuels which will be
allowed by-the permit.
The "high halogen- waste feed" parameter should ideally be
demonstrated during both the minimum combustion temperature POHC
test and the maximum combustion temperature"metals test. By
demonstrating this parameter during the minimum temperature test,
the combined impact of high halogen concentration and low,
temperature on incomplete destruction {and resulting PIC
emissions) can be characterized. The high halogen concentration
is also important during the high temperature metals test to
characterize the impact of chlorinated precursor compounds from
the furnace combined with downstream catalytic formation in the
air pollution control device, particularly for dioxin/furan
compounds. This recommendation assumes that the air pollution1
control device inlet temperature will be higher during the metals
test than the POHC test (although this assumption would have to
be verified on a site-specific basis). Existing data shows that
higher temperatures in dry air pollution control devices result
in higher levels of catalytically-formed dioxins and furans.
In addition to the impact of high halogen concentrations on
downstream PIC formation, high chloride inputs are required
during metals tests because chlorides can affect metals
volatility. Efforts should be made to maintain equivalent
halogen concentrations between the metals and POHC tests, as
variations between the tests could add unnecessary complexity to
development of permit conditions. A specific limit on maximum
chloride/chlorine feed rate is required in the final permit.
3. Wastes Containing Dioxin/Furan Precursor Compounds. As
mentioned previously, dioxin/furans can be formed in dry air
pollution control equipment systems due to fly ash catalyzed
reactions between halogens and undestroyed organic material from
the furnace. Precursor compounds, such as chlorinated phenols
and chlorinated aromatics, can be one source of the organic
material for these reactions since existing data shows a
correlation between dioxin/furan precursors in waste or fuel
feeds and dioxin/furan emission rates.
/
If the facility plans to burn dioxin/furan precursor
compounds, then those compounds should'be represented in the
waste feeds selected for the trial burn. The precursor compounds
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DRAFT 5/2/94
v ' .*-.''
should ideally be present in both the low temperature POHC test
and the high temperature metals test for the same reasons as the
halogen concentration (generally these precursors should be used
for the high halogen feed rate). If the trial burn wastes have
been selected.to adequately represent the types and amounts of
precursor compounds to be burned at the facility, then a specific
permit limit on this parameter is not necessary. .
4. Haloqenated wastes containing ash or metals that can lead to
the catalytic formation of haloaenated organic compounds. As
noted- earlier, certain metals are believed to catalyze low
temperature reactions which can create dioxins and furans. It is
important that this PIC formation mechanism be accounted for in
specification of the trial burn waste. The metals which have
been shown in some cases to catalyze the reactions, include
copper, iron, zinc, nickel, and aluminum; but copper is
considered the most reactive. It is important to note that from
this list, only nickel is considered a pollutant of concern with
respect to human health. However, copper, zinc, and nickel are
of,concern with respect to wetlands ecosystem effects.
Several scenarios can be envisioned. In most instances, it
is anticipated that a strong potential will exist for copper to
be present in the waste stream. If copper is expected to be in
any of the future waste streams to be combusted, it is suggested
that the trial burn waste be doped with, a known loading of copper
chloride (CuCl2) . The precise doping level is currently being ,
investigated but we suggest a.nominal copper doping rate
equivalent to 0.10 to 1.0 weight percent of the total ash
content . If the trial burn is run at this copper, chloride ,
Lxiijk, R., et al., Envir.' Sci. Technol., 1994 28, 312;
National Incinerator, Testing and Evaluation Program:Mass Burn
Technology, Quebec City, Environment Canada, Industrial Programs
Branch, Ottawa, Ontario, December 1987; Kilgroe, J..D., W.S.. Lahier
and T.R. van Alten, Montgomery County South Incinerator Test
.Project: Formation, Emission, and Control of Organic Pollutants,
Municipal Waste Combustion Conference Papers and Abstracts from
Second Annual Specialty Conference, AWMA, Pittsburgh, PA, April,
1991; Gxillett, B.K., P.M.. Lemieux, J.E. Dunn, Role of Combustion
and Sorbent Parameters in Prevention of PCDD and PCDF during Waste
Combustion, Environ.Sci. Technol., Vol 28, No 1, 1994; Robert, S.,
Dioxin Formation and Control in Cement Kilns, Presented at EPA/ASME
Seminar on PIC Formation and Control, RTP,NC, March 8-9, 1994
5 The effects of metals in fly ash or inorganic compounds in
stack gases have been brought into question more recently. Some
metals and inorganic compounds may suppress the formation of dibxin
or speed up its destruction. Metals and organic compounds which
may reduce FCDD/PCDF include sulfur, sodium,, calcium, and
NH,(Takacs,L., Pilot Scale Testing of Ammonia injection Technology
for Simultaneous Control of PCDD/PCDF, HCl and NOx Emissions from
; , ' ; ."' B-9 ,- ' . ' ' . -
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DRAFT 5/2/94
doping level and if acceptable dioxin emission results are
achieved, there is no reason (from a PIC perspective) to set a
permit limit on the feed rate of these metals '(i.e., higher
levels of these metals are not expected to increase dioxin
emissions). If a lower doping rate is negotiated, then the
permit should limit operation to burning of waste with copper and
other potential metallic catalysts loadings at or below those
levels used in the trial burn. If metal doping is implemented,
then it is recommended at both the high and low temperature tests
since the mechanism(s) of the catalyzed reactions are unknown.
An alternate scenario is when wastes fed to the unit will not
contain any of the metals listed above. In that case, doping is
not warranted for the trial burn but the permit should
appropriately limit the composition of waste to be burned.
5. Highly nitroaenated wastes which can lead to formation of ,
nitrogenated PAHs. Some nitrogenated PAHs are highly
carcinogenic. Incineration of wastes containing unusually high
amounts of fuel-bound nitrogen (> 5%) may lead to increased
levels of nitrogenated PAHs. Of particular concern is when the
nitrogen is bound1 in the heavy distillation fractions of the
waste. Such situations may be found with coal tars or bottoms
from petroleum distillation. Formation of nitrated PAHs can
occur in any type of combustion system. Combustor conditions
most likely to result in nitrated PAH release are when the
primary flame is prematurely quenched - low temperature or too
much excess air in the primary combustion chamber. For
facilities burning high nitrogen wastes, the trial burn should
include a test where the unit is operated at the lowest allowed
temperature (or maximum excess air) while burning waste with the
highest levels of bound nitrogen anticipated for that .facility's
normal operation. Doping of the'waste with model nitrogenous
compounds is generally not recommended since this action has the
potential of changing the waste combustion characteristics
depending on the surrogate used. As part of the sampling
protocol for the low temperature test, it is suggested that the
concentration of HCN also be determined, since it is an important
PIC from decomposition of the nitrated waste.
6. Difficult to burn wastes such as highly viscous liquid
wastes, sludge or wastes with easily entrained solid organic
particles. Viscous liquids are difficult to atomize and large .
waste droplets in liquid waste incinerators may escape the high
temperature regions of the combustor before they are completely
destroyed. This process is anticipated to have similar influence
on both POHC and PIC emissions. Accordingly, since this is
Municipal Solid Waste Incineration, Municipal Waste Combustion
Conference Papers and Abstracts from the Second Annual
International Specialty Conference, AWMA, Pittsburgh, PA, April
1991).
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DRAFT 5/2/94
. ' *' - ' . " , ' i
covered in previous guidance, no new guidance is provided
relative to selection of the trial.burn waste.
7. Blended wastes with easily volatilized components. Batch-
fed wastes or wastes in containers can contain substantial
amounts of organic compounds that rapidly volatilize and deplete
the available combustion air,, forming difficult-to-destroy soot
particles. PAHs and nitrogenated PAHs are commonly associated
with soot particles. Trial'burn test conditions for . ; ' '
containerized waste should generally follow current guidance
including consideration of the waste volatility and container
size (see Guidance on Setting Permit Conditions and Reporting
Trial Burn Results).
8. Cement Kilns with Hicrh Levels of Organic Material in the
Feed. CDD/CDF may be formed in the precalciner since it /
appears they are formed in zones where particulate matter and !
organics have a potential for being "held up" for a period of;
time in the temperatxire range of 450-750°F. These compounds may
be formed by devices such as preheaters, precalciners, or PM
control devices. Feed conditions which are expected to pose
problems are high levels of chlorine in the hazardous waste feed
coupled with high levels of organics in the cement raw materials.
Feed condition extremities for developing permit conditions would
be represented by operations with the maximum halogen
concentration in the hazardous waste feed at the same time that
the raw materials contain high levels,of organics.
Emission testing for the maximum levels of organics in
cement kiln feeds should be completed -concurrently with high
halogen concentrations during both the minimum temperature (POHC)
test and the maximum temperature (metals) test since the
formation of PICs in the cold regions of the kiln and the air
ducting system need to be evaluated. However, for many kilns it
is the major source of PICs. Therefore, maximum levels or
concentrations of organics as total organic carbon (TOC) in
cement kiln feed stocks are recommended.
SELECTION OF REAL WASTES BASED ON TOXICITY AND QUANTITY
The previous section discussed a number of waste feed
parameters which can impact two of the three subcategories of, PIC
emissions (i.e., PICs from partial destruction and/or
recoiftbination reactions, and PICs from fly ash catalysed
reactions, such as dioxins and furans)'.,. The last subcategory of
PICs includes unburned organics which were originally present in
the waste feed. For this category of PICs, it.is especially
important to ensure that representative waste feeds are selected
for the trial burn on a site-specific basis considering the
actual "real" wastes that the facility intends to burn. Since
every waste generally cannot be represented during,the trial
burn, it is important to ensure that the trial burn wastes are
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DRAFT 5/2/94
selected using a "reasonable worst case" methodology. The wastes
and or chemicals to be burned should be ranked based on the
constituents in the-various wastes that could significantly
affect the risk assessment if trace amounts of those constituents
went through the combustion process undestroyed. The following
discussion sets forth a methodology for making this ranking. The
permit writer may recommend this methodology or another method
which takes into account these factors and other factors in
developing the trial burn plan.
Application of this methodology results in a list of
preferred constituents or wastes fo;r use in selecting the risk
assessment trial burn waste mixture. This list should only be
considered a tool in selecting real wastes for the test. It is
not necessary that every constituent on the list be represented
during the test. Rather, the list presents a preferred ranking
whereby wastes containing high quantities of constituents on the
list would be considered more likely candidates for the trial
burn than wastes without constituents from the list (or wastes
with low quantities of those constituents). Final waste
selection should include consideration of both the preferred
constituent list and criteria specified in the "Waste Feed
Condition" section of this document (hopefully, some of the
compounds and criteria will overlap). Several real wastes may
have to be used to meet all of the waste criteria, and/or spiking
of real wastes may be necessary. The ranking methodology also
does not include difficulty-of-incineration (incinerability) and
other POHC selection criteria which are applicable since
emissions testing for the risk assessment and ORE determinations
should be combined if possible.
This methodology considers the following factor's:
- Quantity. as reflected by data on historical feed
rates and composition;
- Toxicity. considering both carcinogenic and
non-carcinogenic effects;
- Bioaccumulation Potential, particularly in meat,
fish and milk, given the primary importance of
these routes of exposure.
An example of a waste/chemical selection process consists of the
following five steps discussed below:
1. Selection of Wastes Based on Quantity Burned - The ten organic
constituents or wastes with the highest predicted feed rates
should be considered for the trial burn. This process will
ensure that the hazardous organics expected to be present in the
largest concentrations in'the stack emissions will be included in
the risk assessment. ;
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One way of determining high-quantity organic constituents .
for existing facilities is to review waste profile sheets for all
wastes burned in the past year of operation. The waste profile
sheets typically provide a breakdown of waste composition with
organic and other constituents expressed as range percents. The
mid-point of the range percent for each constituent - can be
combined with the annual quantity burned to determine the
highest-quantity constituents at a given facility. Other
approaches may be appropriate for determining high-quantity
constituents/wastes on a site-specific basis. .
2. Selection of Constituents/Wastes Based on Quantity and
Carcinogenic Potency '- Constituents/wastes should be ranked on
the basis of quantity and carcinogenic potency as determined by
the following equation:
1 ' ."',- ..'."., . j -
QC = (FR)(SF)
where: -
QC = Quantity/Carcinogenic Potency Score
, FR = Feed Rate (or annual quantity burned)
iSF =-Slope Factor (oral or inhalation, whichever is
higher) - , ''.'
The 10 chemicals/wastes with the highest QC scores, if not (
already included in step- 1, should be added to the list.
3. Selection of Constituents/Wastes Based on Quantity and Non-^
carcinogenic Toxicitv - Constituents/wastes should be ranked on
the basis of quantity and non-carcinogenic toxicity using the
, following equation:
QN = FR/RfD
where: . - . - ,
QN = Quantity/Non-cancer Toxicity Score
FR = Feed Rate (or annual quantity burned) ,
RfD = Reference Dose (oral or inhalation^whichever is
' smaller) ."'.' . -'
Note that the units for an oral RfD (mg/kg-bw/day) and an '
inhalation RAC (mg/m ) are different. To accomplish non-
carcinogenic rankings, the inhalation and oral toxicity values
can be converted to similar units using the equation .which was
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DRAFT 5/2/94
utilized to convert oral RfDs to RACs for the boiler/industrial
furnace regulation as follows:
RAC - RfD x body weight x correction factor
cubic meter air breathed/day ,.-'
where:
RfD is the oral reference dose (mg/kg-bw/day); -
Body weight is assumed to be 70 kg for an adult male;
Volume of air breathed by an adult male is assumed to be 20
cubic meter/day;
Correction factor for route to route extrapolation is
assumed to be 1.0;
As an alternative to the above transformation, the QN score could
consider only the inhalation RAC, and the QNB Score below could
consider only the oral RfD.
The 10 constituents/wastes with the highest QN score, if not
already included in steps 1 and 2, should be added to the list.
4. Selection of Constituents/Wastes Based on Quantity,
Carcinogenic Potency and Bioaccumulation Potential -
Constituents/wastes should be ranked on the basis of quantity,
carcinogenic potency, and bipaccumulation potential using the
following equation:
QCB = (FR)'(SF) (logKOH)
where: .
QCB - Quantity/carcinogenic Potency/Bioaccumulation
Potential Score
FR = Feed Rate (or annual quantity burned)
SF = Slope Factor (oral or inhalation, whichever is
highe
r)
logKOH = The logarithm of the octanol-water partition
coefficient, which is related to a
chemical's bioaccumulation
potential in milk and meat.
The 10 constituents/wastes with the highest QCB score, if not
already included in steps 1, 2, or 3 should be added to the list.
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DRAFT 5/2/94
i - ' . . :
5. Selection of Constituents/Wastes Based on Quantity. Non-Cancer
Toxicity. and Bioaccumulation Potential - Constituents/wastes
should be ranked on the basis of quantity, non-carcinogenic
;toxicity, and bioaccumulation potential using the following
equation: ' ; .
QNB = (FR) (logK0J/RfD
where:
" QNB - Quantity/Non-carcinogenic .
Toxicity/BioaccUmulation Potential Score ,
FR = Feed Rate (or annual quantity burned)
logKpH = The logarithm of the octanol-water partition
coefficient
RfD = Reference Dose (oral or inhalation, whichever is
smaller)"
The 10 constituents/wastes with the highest QNB scores, if not
already included in Steps 1> 2,3, or 4 should be added to the
list. ; i ' ''.'.'.-. ..'-../, ,.."..
DEVELOPMENT OF PERMITTED OPERATING CONDITIONS
Operating conditions other than those associated with waste
feed conditions can also affect the formation and emission of
PICs. All thermal destruction processes operate over a range of
conditions and it is important to conduct trial burn tests over
the range of operating conditions for which the process is to be
permitted. Combustion and flue gas cleaning device operating
conditions which should be considered when defining acceptable
operating conditions with respect to PICs are as follows:
1. Minimum Combustion temperature and residence time.
' Combustion reaction rates decrease with decreasing temperatures
resulting in decreased POHC destruction and increased PIC
formation. At lower temperatures, longer residence times are
required for complete destruction ,of gas .phase and condensed
phase organics,, At least one trial burn condition should be at
the minimally-acceptable combustor operating temperature and
residence time. (According to the regulations, residence time Is
determined by an indicator of combustion, gas velocity.)
Low combustion temperatures can result from \a number of
causes: low waste heating values, high excess air levels and
excessive heat extraction rates. Excessive heat extraction rates
are not expected to be a problem in well designed and operated
combustors. Some wastes have low heating values because of their
inherent composition (high moisture content, high-ash content, or
chemical .composition). If low heating.value wastes are burned at
' ' ' B-15 " - '.-' . ."
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DRAFT 5/2/94
a facility then these "low BTU" wastes should be used during the
trial burn tests in combination with maximum excess air rates to
produce the minimum expected combustion temperatures at which the
facility expects to operate. Minimum combustion temperatures
could also be achieved by lowering waste feed rates. However,
this method is not desirable during trial burns because of the
need to maximize waste feed rates and thermal input for the
ultimate permit conditions, and because lower feed rates may not
result in minimum residence times.
When low BTU. wastes are not burned at a facility, it may be
difficult to operate at reduced.combustion temperatures without
operating at abnormal combustion conditions. For moderate and
high BTU value wastes, the lowest expected combustion
temperatures and residence times might only be achievable by
operating at maximum excess air conditions. As discussed under
item 4 below, "Maximum excess air rates" should be provided as
primary air.
The permit writer should also consider other factors besides
waste, fuel, and air feed rates which can affect residence time.
These factors include residues, including slag or ash build up in
the combustion chamber as well as increases in the aqueous
content and oxygen content of the waste or fuel. Trial burns
should generally be tested at the highest moisture level which..
would be expected during the life of the permit (low temperature
tests) in order to assure high moisture content will not
adversely effect the combustion process or cause excessive
pressures.
The minimum combustion temperature and residence time
conditions should be demonstrated during the low temperature POHC
test, and specific permit limits are required for both
parameters. Maximum combustion gas velocity (continuously
monitored as an indicator of minimum residence time) is also
required to be demonstrated during the high temperature metals
test, with a subsequent permit limit. Because setting a
combustion velocity limit is necessary with respect to the
residence time and metals testing, it is desirable" to maintain
the same maximum combustion gas velocity during both the POHC/PIC
and metals tests.
2. Amount and distribution of combustion air . The proper
amount and distribution pf combustion air is essential for
efficient combustion. The amount of excess air must be
sufficiently high and it must be adequately distributed to
minimize the existence of fuel-rich pockets. Alternatively,
overly high excess air levels or poor combustion air distribution
This discussion applies to complete combustion devices and
not to pyrolytic devices which are addressed in previous trial burn
guidance.
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DRAFT , 5/2/94
can quench combustion reactions. The range of excess air levels
that will satisfy these objectives varies for each combustor
technology. ,
The appropriate range for excess air or oxygen concentration
in a combustion device is dependant on a wide variety of site
specific conditions including the waste characteristics and the
details of the fuel/air mixing process! For any given combustion
system, there is an optimum range of excess air, but that optimum
is highly site specific. As the system excess air is decreased
from the optimum, the amount of oxygen available to oxidize
organic constituents is reduced. Eventually, a condition is
reached where the most difficult to oxidize compound will be
released from the furnace. That compound is carbon monoxide
(CO). Further reduction in available excess air will lead to
increased CO concentrations. Thus, emission limits for CO are
one method for assuring that wastes are not fed to the unit while
excess air is at too low a level.
Regardless of .the CO limit safeguard, some hazardous waste
combustion systems have been known to operate under conditions
which result in reaching or exceeding the CO permit limit. A
very effective, automatic combustion control system is being
widely employed which is based on continuous measurement of
oxygen concentration. Some systems sense the O2 level in the
stack while others sense O2~ level while the gases are still quite
hot. In either mode, a site-specific .optimum excess oxygen
condition may be determined. A signal from the oxygen monitor is
then used to modulate a damper in the combustion air supply line
or to modulate the,total heat input. The overall objective is to
maintain the overall fuel to air ratio as nearly constant as
possible. -. .
" ' A
An automatic control system for maintaining fuel-air ratios
is a highly desirable system feature for combustors burning any
waste, but is especially important for units burning hazardous
waste. This guidance encourages, but does not require, their
inclusion as part of permitted RCRA combustion operations. Such
control systems will help assure continuous operation within the
defined envelope, thus minimizing the number of permit
exceedances. , ' , ,
For combustion systems fired continuously and with discreet
charges (e.g. containerj-ed) of waste, oxygen availability is
critical because the rapid release of volatile matter from each
charge of waste or combustibles consumes large quantities of
available oxygen. If the instantaneous oxygen demand exceeds the
available oxygen, there will be a dramatic increase in the PIC
generation rate as well as,a change in composition of the PICs
generated. Because some control systems cannot effectively
respond to instantaneous O2 demands, the trial burn must be
designed to develop permit conditions which ensure that short
term oxygen demand does not exceed the available oxygen supply
B-17 . _. .
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DRAFT 5/2/94
when feeding containers (or the facility can upgrade its control
system). ,
As stated in previous guidance, the containerized feed used
during the trial burn should represent both the largest container
size and the maximum amount of volatile, high BTU materials that
will be fed during normal operations. A new recommendation of
this guidance is that the combustor should be operated during the
trial burn at a "baseline" oxygen concentration that represents
the minimum level that the facility wishes to maintain as a
permitted condition for treating containerized waste . In this
context, the baseline oxygen concentration is defined as the
steady state oxygen concentration that exists in the absence of
containerized feeds. When a fresh charge is added, the oxygen
level will drop below that baseline, but it should not be allowed
to drop below the levels measured during the trial burn, since
the "worst-case" containers (i.e., maximum volatility and size)
are being fed during the trial burn. Therefore, during normal
operation, the unit should not go into a pyrolytic mode of
operation with high emissions of CO, HC and PICs. This condition
should be demonstrated during the low temperature POHC test
unless it conflicts with the minimum residence time parameter
(which may be achieved by using an increased amount of excess
air) .
Based on the trial burn results, the permit writer should
establish permit conditions on container size and the minimum
baseline oxygen concentration which must be met as a permitted
condition for containers to be treated in the unit. The permit
should also require that the container feed mechanism be
automatically locked out when the measured oxygen concentration
is below the established baseline. For a unit which consistently
experiences CO excursions, it is recommended that both the O2
lockout and the previously mentioned automatic combustion
fuel-to-air control system be system additions, if not already
part of the combustion system.
3. Maximum thermal input rates. Excessive thermal input rates
(including both wastes and auxiliary fuel) can result in
operation of the combustor above design operating conditions.
High thermal input rates result in reduced combustion product
residence times within the high temperature regions of the
furnace. This situation reduces the time .available for
destruction of gas-phase PICs and solid organic particles
entrained in the flue gas. High thermal input rates also result
in increased entrainment of particulate matter and carryover of
The use of a permitted baseline oxygen concentrations may
not be required in all cases since the facility may have means of
quickly increasing oxygen availability (i.e., by the use of
dampers). These devices or systems should be demonstrated during
the trial burn.
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DRAFT , . 5/2/94
this material into boiler passages and air pollution control ,
devices. Prior guidance-he-is been provided for setting trial burn
test conditions representing reasonable worst case thermal input
conditions. These conditions may result in reasonable worst case.
conditions for PIC formation.
Ideally maximum thermal input rates should be demonstrated
during both the minimum temperature POHC test and the maximum
temperature metals test. A maximum thermal input rate should be
established in the permit based upon the measured thermal input .
rates during the tests. Efforts should be made to maintain
equivalent thermal inputs between the metals and POHC'tests, as ,
variations between the tests could add complexity to development
of permit conditions. Although it may be difficult to , -
simultaneously achieve a maximum thermal input rate and minimum
combustion temperature for the POHC test, adjustments to excess
air rates and waste moisture contents can help mitigate the
conflicts between these two parameters.
4. Maximum Temperature at inlet to theparticulate matter
control device. PM control devices such as electrostatic
precipitators and bag houses contain large amounts of PM and
under certain conditions they can act as a chemical reactor for
the formation of trace organic compounds. This situation is
particularly true relative to dioxins and furahs. Available data
shows that there is generally a net increase of CDD/CDF across
particulate collection devices operated in the temperature range
of 450 to 750°F. Generally, a zero change in CDD/CDF
concentration across the control device simply means that removal
of dioxins formed in the furnace region is matched by, additional
formation in the APCD. Data from several classes of combustion
systems have demonstrated that CDD/CDF formation continues at
lower temperature but that the formation rates are substantially
reduced at temperatures below 300°F. In fact, the data indicates
that reducing APCD temperature by 125°F will reduce the low .
temperature dioxin formation rate by an order of magnitude.
.Trial burns should include operations at the maximum temperature
at which electrostatic precipitators or fabric filters are
expected to operate and should also reflect minimally acceptable
combustion conditions. With regard to the development of
permitted combustion conditions, the primary concern here is-.to-
select, conditions which maximize the carry-over of particulate
matter to the APCD. This situation is normally achieved with
maximum gas velocity in the primary combustion region. This
condition may be distinctly different from maximum gas velocity
in the overall system. .
' " ''''",- '
The maximum APCD inlet temperatures and maximum gas velocity
parameters should ideally be demonstrated during the high
temperature metals test, and specific permit limits are required
for both parameters.
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DRAFT 5/2/94
5. Other Conditions. Other conditions, such as flue gas
cleaning equipment operating variables, can be tested at minimal-
acceptable operating conditions. An example of this type of
requirement would be the minimum rate at which activated carbon
is injected to provide supplementary control of CDD/CDF. Another
operating condition to be considered in planning trial burns for
PICs is the occurrence of soot blowing. Prior guidance on this
issue was provided for BIF's in "Technical Implementation for
EPA's Boiler/Industrial Furnace Regulations". That same guidance
should be followed relative to PIC emission evaluations.
More recently there has been discussions about the injection
of additives or sorbents to the air system after the combustion
device (similar to activated carbon injection). These materials
include calcium, sodium, and sulfur which are believed to
minimize the formation of dioxin by scavenging C12. Permit
writers must be aware of any injections to the air system during
the trial burn and incorporate them into the permit as
appropriate. " ' -
APPLICATION OF DATA ' - ...
Traditionally, trial burns have included special tests for
metals where the system operating temperature is maximized and
tests for POHC emissions where system temperatures are minimized.
For the purposes of the risk assessment, it is recommended that
PICs be quantified under both sets of operating condition's. With
regard to use in the risk assessment, the emission value used- for
PIC and metal constituents should be an average of results ^ from
three runs completed for a given waste or operating condition.
The test condition which gives the highest risk should be the
values used in.the risk assessment. This procedure will likely
result in the need to calculate the risk for more than one test
condition if it is not obvious which test condition represents
the higher risk.
If there are great differences in the results for the
individual runs in a set of test runs or conditions, the average
value may not be appropriate. The cause ,of the disparity should
be determined and a more appropriate value may be selected by the
permit writer or he/she may require a retest.
The above discussion does not revise the previous
methodology for determining noncompliance with emissions limits.
Historically, this determination is based on a single run.
Therefore, each run of a test must pass to be permitted at that
condition. There is no change in this approach at this time.
PARTICULATE SIZE DISTRIBUTION
Both the deposition and vegetative uptake algorithms used in
the risk assessment models require information on particle size.
Although site-specific ambient particle size data that is
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DRAFT * 5/2/94
representative of the interaction of the combustion device
particles and the background aerosol is preferred, such data may
be difficult to obtain. Particle size distribution of the
emissions may:be measured directly, or may be estimated from
information in the "Compilation of Air Pollutant Emission
Factors" (AP-42) (available from the Government Printing Office).
The information in AP-42 is applicable mainly to BIFs.
EXEMPTIONS . . ':'.-/.
It is important to note that planning and execution of trial
burns and development of risk assessments based on .trial burn
results is extremely involved and expensive, and that under
special conditions, it may not always be justified. Earlier
guidance and regulations for trial burn planning recognized this
fact and gave permit writers flexibility to forego DRE trial
burns under three separate scenarios. These scenarios .included
(1) Incinerators burning waste with no or insignificant hazardous
constituents, (2) BIF's qualifying for the low risk waste
exemption, and (3) boilers under special operating conditions.
/Under conditions where, in the opinion of the permit writer, no
DRE trial burn is necessarily required, consideration may also be
given to excluding the facility from PIC trial burn testing. In
screening such facilities, the permit writer must carefully
evaluate any available data (including historical PIC emissions
'data, waste types, presence of halogens, volumes, and toxicity)
from similar facilities burning similar waste. Special attention
should be given to any data concerning dioxin and furan emissions
from similar facilities, including similar units burning non-r
hazardous wastes. In screening such data, the permit writer must
be particularly mindful of the guidance presented in the previous
sections to assure that-provided data represents a_realistic
assessment of anticipated reasonable worst case emissions. Based
on such a screening review, which must include historical data on
CO and/or HC, a waiver of the PIC trial burn could be in order.
Until further guidance is developed on this issue, it is (
recommended that permit writers considering such an exemption
consult with OSW.
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DRAFT
5/2/94
Feed Parameter
Organic Types
Nitrated Waste
Metal Catalyst
Halides/Halogens
Ash
POHC
BIF Metals
Volatility
Precursors
TOG of Kiln
Feed
TRIAL BURN
EXAMPLE TEST MATRIX
PIC/POHC Test
Representative
Representative
Maximize CuCl
Maximum
Maximum
Based on POHC
Selection Criteria
Representative
Maximum
Representative
Maximum
Combustion Parameters
Container Size Maximum
Combustion Temp. Minimum
Thermal Input Max."if poss
Combustion Gas Vel. Maximum
Oxygen Content Minimum
Permit
Condition
N
N
Y
as appl.
Metals Test
Representative
Representative
Representative
Maximum Y
Maximum Y
Same as POHC/PIC N
Test
Maximum . Y
Representative N
Representative N
Representative N?
, Maximum
Maximum
Maximum
Maximum
Minimum
Y
Y
Y
Y
Y
for
Batch
Soot Blowing
Representative
Representative
N
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DRAFT , 5/2/94
PIC/POHC Test Metals Test Permit
- Condition
\ '..'. : ' ' .' ' . '_.''. . . ' ' .; .' : .'" . (Y/N)
APCD Conditions
Temperature Representative Maximum Y
AP Minimum Minimum Y
Rapping or Cleaning. Normal Maximum >
Rate " ' .- . -' ' ; -.-.".. .-"'..'"
Other APCD Parameters - As per previous,guidance.
, B-23
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DRAFT 5/2/94
Resource Documents:
Guidance on Setting Permit Conditions and Reporting Trial Burn
Results; EPA/625/6-89/019, January 1989. ,.
Technical Implementation Document for EPA's Boiler and Industrial
Furnace Regulations; EPA/530-R-92-011; NTIS# PB92-154 947, March
1992.
Combustion Emissions Technical Resource Document (Draft); EPA,
April 1994
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DRAFT AprUlS, 1994
Attachment. C ', . ' , . ' _."
GUIDANCE FOR PERFORMING SCREENING LEVEL
RISK ANALYSES AT COMBUSTION FACILITIES
BURNING HAZARDOUS WASTES
Office of Emergency rnd Remedial Response
Office of Solid Waste
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DRAFT Aprill5,1994
1. INTRODUCTION
1 .. . ' . ' ' '."' " ' \
This document provides guidance for performing a screening level analysis of direct and
indirect human health risks from combustion emissions. The screening procedure is intended
to give a conservative estimate of the potential risk in order to determine whether a more
detailed site-specific assessment is warranted. The screening guidance provides information on
the constituents, exposure scenarios, indirect pathways, and parameter values that are needed
for estimating risk. The document is designed as a kind of "workbook" that is clear, concise,
and simple to use.
, the screening procedure is based on the guidance in the January, 1990 interim final report
Methodology for Assessing Health Risks Associated with Indirect Exposure to Combustor
Emissions (EPA/600/6-90/003 and referred to as the Indirect Exposure Document), the draft
Addendum to the Indirect Exposure Document (dated November 10, 1993), and the draft
implementation guidance entitled "Implementation Guidance for Conducting Indirect Exposure
Analysis at RCRA Combustion Units" .(dated April 22, 1994 and referred to as the
Implementation Guidance). In the interest of simplicity, the procedure has been streamlined by
reducing the number of,algorithms mat need to be evaluated, while retaining the degree of
conservatism appropriate for a screening level analysis. ";'...
The screening guidance specifies the particular exposure scenarios that should be evaluated
and provides default values for most input parameters. In addition, the screening guidance also
allows the flexibility to use available site-specific information to modify certain assumptions.
For example,, site-specific land use information may be used to determine that certain
assumptions regarding the exposure scenarios are implausible (e.g., that exposure occurs at the
points of maximum air concentration and maximum deposition) and to make alternative
assumptions (e.g., to identify locations at which the exposure scenarios used'for the screening
analysis are plausible). If the final estimated risk'is below levels of concern, then there is good
reason to conclude that further analysis of the risk from stack emissions is unnecessary.
', The primary focus of the screening guidance is on indirect exposures. However, in order
to characterize the risk from stack emissions it is necessary to characterize the risk from direct
inhalation exposures as well. The screening guidance, therefore, includes a brief discussion of
estimating risk from direct inhalation exposures. It is important to recognize that the
constituents for which direct inhalation exposures are of primary concern may be different from
(and generally more numerous than) those for indirect exposures.
The endpoihts of the screening analysis are estimates of individual risk for several exposure
scenarios. The exposure scenarios selected for the screening analysis are considered to be the
most significant ones for combustion sources. For each scenario, the risk estimates are based
on combining exposures and risk for an individual constituent across several pathways. Where
appropriate, risk from multiple constituents are also combined to provide estimates .of overall
risk for each exposure scenario. . ' ,
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DRAFT April 15, 1994
As indicated in the text box, in the following sections the document gives a general
overview of the screening approach (Section 2), discusses the required air dispersion and
deposition modeling and input parameters (Section 3), presents the equations to use and gives
default parameter values for ,
calculating media ^^^^^^^"^^^i^
concentrations for each of the Section!. Introduction
pathways that are associated Section 2. ' Overview
with indirect exposures Sections. Air Dispersion and Deposition
(Section 4), provides all Modeling
necessary chemical-specific Section 4. Indirect Exposure Pathway
parameter values (Sections), ~~ Equations
and explains how to Sections. Chemical-Specific Parameters
characterize risk for each of Section 6. Risk Characterization
the exposure scenarios in the
Screening analysis (Section 6). 'mmmmmmim^mfi^immmmmmm^^mmmmammm^m^mmmmmmmmm^^
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DRAFT , AprU 15, 1994
2. OVERVIEW
This section gives an overview of the screening approach to the analysis of indirect and
direct exposures to combustion emissions. This section highlights key aspects of the screening
guidance, including constituents to evaluate, exposure scenarios that form the basis of the
analysis, atmospheric dispersion and deposition modeling that represents the initial fate and
transport of constituents hi the environment, fate and transport of constituents in soil, terrestrial
food .chain,- and aquatic food chain pathways that lead to indirect human exposures, and
characterization of risk to individuals from both direct and indirect exposures.
2.1 Constituents
The screening approach for analyzing indirect exposures to combustion emissions focuses
on a limited number of constituents, 'these constituents have been selected based on an analysis
of their potential to pose increased risk by means of one or more of the indirect exposure
pathways. The constituents selected include metals and organic compounds that are believed to
be products of incomplete combustion (PIC's). Among the constituents selected- are those that
are considered to present the highest risks to human health via indirect exposures.
For direct inhalation exposures, however, there are .many constituents that could pose
increased risk. Therefore, the screening analysis should include all constituents for which stack
emission data and inhalation health benchmarks exist, Le., unit risk, factors or reference
concentrations (RfCs), for the purpose of estimating risk from direct inhalation exposures.
The constituents to be included in the indirect exposure assessment are the following:
Dioxins and Dioxin-like Compounds , . '
2,3,7,8-substituted Polychlorinated dibenzo(p)dioxin congeners (2,3,7,8-PCDD's)
2,3,7,8-substituted Polychlorinated dibenzofuran congeners (2,3,7,8-PCDF's)
All emissions of 2,3,7,8 substituted polychlorinated dibenzo(p)dioxins and dibenzofurans are
converted to 2,3,7,8-tetrachlorodibenzo(p)dioxin(2,3,7,8-TCDD)toxicity equivalents following
EPA's Interim Procedures for Estimating Risks Associated with Exposures to Mixtures of
Chlorinated Dibenzo-p-Dioxins and Dibenzofurans (CDDs and CDFs) (U.S. EPA, 1989). All
congeners are then modeled using the fate and transport properties of 2,3,7,8-TCDD.
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DRAFT April 15, 1994
Polvcyclic Aromatic Hydrocarbons (PAH's)
Benzo(a)pyrene
Benz(a)anthracene
Benzo(b)fluoranthene
Benzo(k)fiuoranthene
Chrysene
Dibenz(a,h)anthracene
Indeno(l,2,3-cd)pyrene
Based on comparative potency estimates provided in EPA's Provisional Guidance for the
Quantitative Risk Assessment of Polycyclic Aromatic Hydrocarbons (Office of Health and
Environmental Assessment, 1993) emissions of these PAH's are converted to benzo(a)pyrene
toxicity equivalents (BaP-TEQ). All PAH's are then modeled using the fate and transport
properties of benzo(a)pyrene.
Polvchlorinated Biphenvls (total PCB's)
total Polychlorinated biphenyls (all congeners)
All polychlorinated biphenyl congeners (209 congeners) are treated as a mixture having a single
carcinogenic potency, as recommended hi EPA's Drinking Water Criteria Document for
Polychlorinated Biphenyls (PCBs) (U.S. EPA, 1988).
Nitroaromatics
1,3-Dinitro benzene .
2,4-Dinitro toluene
2,6-Dinitro toluene .
Nitrobenzene
Pentachloronitrobenzene . ,
Phthalates '..-...
Bis (2-ethyUiexyl) phthalate - .
Di(n)octyl phthalate
Other Chlorinated Organics '
Hexachlorobenzene
Pentachlprophenol
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April 15, 1994
Arsenic ; , , , . '
Beryllium
Lead- '. ; ''.- ' ' " -'.,'".,. / ..'..''.';.
.Mercury
*-'_-.'..' . . - .
2.2 Emission Estimates -
The draft Addendum and the Implementation Guidance provide "guidance on estimating
emissions from combustion sources. This guidance should be followed when determining the
emission rates to use in the screening analysis.
2.3 Human Exposure Scenarios
Four human exposure scenarios have been developed for.use in the screening analysis: a
subsistence farmer, a subsistence fisher, an adult resident, and a child resident. These exposure
scenarios differ primarily in consumption rates of contaminated foods. In particular, subsistence
farmers consume more contaminated beef arid milk than the general adult population and
subsistence fishers consume more contaminated fish than the general population. While the
general population may also consume contaminated beef, milk, and fish, a much larger fraction
of the consumption of these foods is likely to be contaminated 'for a subsistence farmer or fisher
because subsistence farmers and fishers may obtain these foods from a single source. Table 2.1
presents the rates of consumption of contaminated food, ingestion of contaminated soil, and
inhalation of polluted air for each of the four exposure scenarios.
All of these exposure scenarios should be evaluated for making screening level estimates
of risk. However, site-specific information (e.g., local land use data) may indicate that .the
subsistence farmer or fisher or adult resident or child may not be exposed at the locations of
maximum air concentration and maximum deposition. In such cases, these scenarios should
continue to be included hi the screening analysis based on alternative locations of exposure, as
described in Section 3. The exposure scenarios are described hi the following paragraphs.
Guidance on characterizing the risk for each scenario is provided hi Section 6.
Subsistence Farmer
In the subsistence farmer scenario, an adult farmer is exposed via consumption of
homegrown beef and milk, consumption of homegrown vegetables, incidental soil ingestion,
and direct inhalation of vapors and particles. The subsistence farmer is assumed to raise cattle
for both ,beef and milk consumption and grow crops for home consumption. Site-specific
information could be used to modify these assumptions.
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DRAFT April 15, 1994
Table 2.1. Consumption Rates and Fraction Contaminated Used in Exposure Scenarios
Contaminated food or media
Beef (g/day)
Milk (g/day)
Fish (g/day)
Above-ground vegetables
(g DW/day)
Root vegetables (g DW/day)
Soil (ring/day)
Air (m3/day)
Exposure Scenario
Subsistence
Farmer
Rate
100
300
NA
24
6.3
100
20
Frac.
0.44
0.40
NA
0.95
0.95
1
1
Subsistence
Fisher
Rate
NA
~NA
140'
24
6.3
100
20
Frac.
NA
NA
1
0.25
0.25
1
1
Adult
Resident
Rate
NA
NA
NA
24
6.3
100
20
Frac. ,
NA
NA
NA
0:25
0.25
1
1
Child
Resident
Rate
NA
NA
NA
5'
1.4*
200
5*
Frac
NA
NA^
NA
0.25
0.25 .
1
1
Notes: DW = dry weight NA = not applicable " = provisional value for interim use only
All values from the Exposure Factors Handbook (U.S. EPA, 1990a).
Units shown are for consumption rate; all fractions contaminated are dimensionless.
Consumption rates for contaminated beef, milk, above-ground vegetables, and root
vegetables are representative of a typical subsistence farmer, rather than the general population.
Exposures to crops include consumption of both above-ground vegetables and root vegetables.
The incidental soil ingestion rate and the inhalation rate are typical for adults.
Subsistence Fisher .
In the subsistence fisher scenario, an adult fisher is exposed via consumption of
contaminated fish and homegrown vegetables, incidental ingestion of soil, and direct inhalation
of vapors and particles. Both finfish and shellfish are considered. Fish consumption rates are
intended to be representative of a typical subsistence fisher, rather than the general population..
However, limited data are available on rates of fish consumption by subsistence fishers.
Therefore, the consumption rate given in Table 2.1 is provisional and is intended for interim use
only. Consumption rates for above-ground vegetables and root vegetables and the incidental soil
ingestion and inhalation rates are typical for adults. .
Adult Resident
In the adult resident scenario, an adult is exposed via consumption of homegrown
vegetables, incidental soil ingestion, and direct inhalation of vapors and particles. Exposures
to homegrown vegetables include both above-ground vegetables and root vegetables.
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DRAFT April 15, 1994
Consumption rates for above-ground vegetables and root vegetables and the incidental soil
ingestion and inhalation rates are typical for adults.
Child Resident
In the child resident scenario., a child is exposed via consumption of homegrown
vegetables, incidental soil ingestion, and direct inhalation of vapors and particles. Exposures
to homegrown vegetables include both above-ground vegetables and root vegetables. The
incidental soil ingestion rate is typical for children. Consumption rates for above-ground
vegetables and root vegetables and inhalation rates that are typical for children are not available;
the values given in Table 2.1 are provisional and are intended for interim use only.
2.4. Air Dispersion and Deposition Modeling
The COMPDEP air dispersion and deposition model is used to estimate air concentrations,,
and wet and dry deposition rates. The model requires hourly surface wind, cloud cover, and
precipitation observations and twice daily mixing heights. The meteorological data should be
representative of conditions at the site. The model is run once/using a "unit" emission rate
(i.e;, 1 gram/second) with both dry and wet deposition options selected. The results of this run
are used for both air concentrations arid deposition rates of particles and vapors. The values
obtained using the unit emission rate are adjusted to cheriiical-specific air concentrations and,
deposition rates using chemical-specific emissions rates. Vapor-particle partitioning is not
considered as part of the air dispersion and deposition modeling; rather, adjustments are made
to the modeled air concentrations to account for vapor-particle partitioning as part of the indirect
fate and transport pathways analysis in Section 4.
The point of maximum combined wet and dry deposition, as output by the COMPDEP
model, is used as the point of departure for all indirect pathway exposures. If the risk estimated
frorn this very conservative assumption does not indicate a problem, no further analysis is
necessary. However, site-specific information (e.g., land use data) may be used to determine
the locations of the agricultural field and the watershed of concern and the size of the watershed.
(A default watershed size is provided if the requisite information is not available locally.) It is
recommended that the locations of maximum air concentration and maximum combined wet and
dry deposition be used for the child and adult resident exposure scenarios unless these points are
predicted to occur at locations where it is clearly implausible that a residence could be located
(e.g., over a large lake or within a large industrial area).
Direct inhalation exposure is evaluated at the location of die maximum air concentration.
The maximum air concentration is assumed to be collocated with the point of maximum
combined wet and dry deposition. However, this assumption may be modified if site-specific
information is used to identify alternative locations for use in evaluating the exposure scenarios.
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DRAFT April 15, 1994
2.5 Indirect Exposure Pathways
For screening purposes, indirect exposures include ingestion of above-ground vegetables,
root vegetables, beef and milk, fish and shellfish, and soil. Contaminants in combustion
emissions may reach these media or foods by many pathways. The pathways that provide the
highest media or food concentration have been selected for use hi the screening analysis.
Different pathways give the highest concentrations for different constituents. For example, soil
erosion gives the highest water concentration for some constituents, while runoff gives the
highest water concentration for other constituents. In these cases, constituent-specific guidance
is provided in Section 4. . .
For the indirect exposure pathways analysis, a combination of two parameters that have
the greatest impact on media or food concentrations are set at "high end" values, while other
parameters are set at typical or "central tendency" values. This will provide a high end estimate
of the concentration of the constituents hi the media or food. Tables in Section 4 and Section 5
provide all parameter values that need to be used hi the screening analysis..
The indirect exposure pathways selected for screening analyses are described hi the
following paragraphs.
Above-ground Vegetables
Above-ground vegetables are ingested by humans and cattle. Cattle ingestion of
above-ground plants is discussed below hi the sections for beef and milk. For human ingestion
of above-ground vegetables, the following two pathways of contaminant transport are included:
deposition of particle phase contaminants directly onto plant surfaces and direct transfer of vapor
phase contaminants into plant material. One or the other of these pathways may dominate or
be inapplicable for specific constituents. 'Constituent-specific guidance is provided hi Section 4
on which of these pathways should be considered.
Root Vegetables , ,
For ingestion of root vegetables by humans, contamination by root uptake of contaminants
deposited on soil is included. Because this is the only pathway for root vegetables, it should be
included for all constituents (except lead).
For ingestion of beef, three pathways are included. The first is deposition directly onto
forage plant surfaces followed by cattle consuming contaminated forage and bioaccumulation hi
muscle tissue. This pathway should be included for all constituents (except lead). The second
pathway is direct transfer of vapor phase contaminants into forage plant material followed by
cattle consuming contaminated forage and bioaccumulation in muscle tissue; this pathway should
be included only for selected constituents, as indicated hi Section 4. The third pathway is
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DRAFT April 15, 1994
'-,-' ' i
incidental ingestion of soil by cattle and bioaccumulation hi muscle tissue. This pathway should
be included for all constituents (except lead).
ilk ' : . i -' '".-.:' '':;."
For ingestion of milk, three pathways are included. The first is deposition directly onto
forage plant surfaces followed* by dairy cattle consuming contaminated forage and
bioaccumulation hi milk. This pathway should be included for all constituents (except lead),
The second pathway is direct transfer of vapor phase .contaminants into forage plant material
followed by dairy cattle consuming contaminated forage arid bioaccumulation hi milk; this
pathway should be included only for selected constituents, as indicated in Section 4. The third
pathway is incidental ingestion of soil by dairy cattle and bioaccumulation hi milk. This,
pathway should be included for all constituents (except lead).
Fish , . . ':''--'".. .
For ingestion of fish, the following pathways are included:
deposition onto the watershed, followed by soil erosion into the waterbody, followed
by bioaccumulation of contaminant from total water column concentration to fish
; - tissue; , ''"',.' : ~ , ' -,'''
deposition onto the watershed, followed by soil erosion into the waterbody, followed
by deposition into the bed sediment, followed by bioaccumulation in fish tissue;
deposition onto the watershed, followed by rjunoff into the waterbody, followed by.
bioconcentration of contaminant from dissolved water concentration, to fish tissue;
and deposition directly onto the waterbody, followed by bioaccumulation of
contaminant from total water column concentration to fish tissue
Which of these pathways should be included depends on the constituent, as indicated hi
Section 4. , ,
soli .. " ' '; _ .' ' ' - ; ';. . .' "
For incidental ingestion. of .soil by adults and children, contamination by deposition onto
soils should be included hi the screening analysis for all constituents.
2.6 Risk Characterization
The screening analysis provides estimates of risk that are based on a combination of high
end values for some parameters and central tendency values for other parameters. The following
high end assumptions are used: :
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DRAFT April 15, 1994
Emissions from the combustion source for each constituent generally represent high
end values. The Implementation Guidance for Conducting Indirect Exposure Analysis
at RCRA Combustion Units provides guidance for determining metals and organic
emissions.
Air concentration and deposition from the locations of the maximum air concentration
and maximum combined wet and dry deposition are used as the point of departure.
However, alternative locations may be considered. Additional guidance for
identifying alternative locations is provided in Section 3.
Two fate and transport parameters hi fee .indirect pathways analysis are set to high
end values. The two high end parameters are the two most sensitive parameters (or
groups of related parameters) that have been determined by sensitivity analysis. The
two high end parameters depend on the exposure pathway. Specific guidance on high
end parameters for each pathway is provided in Section 4.
. The exposure duration for each exposure scenario is set to a high end value. The
values for exposure duration are given in Section 6.
,1 ' ' ' ' ' i ' '
Use of these assumptions with the exposure scenarios described hi Section 2.3, together
with simplify ing conservative assumptions hi the exposure pathways analysis, will ensure that
the results represent high end or bounding estimates of risk. If there actually are subsistence
farmers, subsistence fishers, or residents in the area of concern, the risk estimates will represent
conservative high end estimates of risk. However, if there are not subsistence farmers,
subsistence fishers, or residents hi that area, the risk estimates will represent bounding estimates
of risk for the general population.
Additivity of Pathways Within an Exposure Scenario
The exposures from the indirect pathways should be combined for each scenario and
constituent. Therefore, for the subsistence farmer scenario, exposures from ingestion of beef,
milk, above-ground vegetables, and root vegetables, and incidental soil ingestion should be
added together for each constituent. For the1 subsistence, fisher i exposures.from ingestion of fish,
above-ground vegetables, root vegetables, and soil should be added together for each constituent.
In the adult and child resident scenarios, exposures from ingestion of above-ground vegetables
and root vegetables and incidental soil ingestion should be added together. However, adult
exposure and child exposure are considered separately and should not be combined. The end
result is one oral exposure (dose) for each scenario and constituent. Given these exposures, a
carcinogenic risk and, for non-cancer effects, a hazard quotient is calculated for each scenario
and each constituent. (Note that a hazard quotient cannot be calculated for lead, as no health
effects benchmark has been established for lead. Therefore, only soil concentrations are
calculated for lead.) ~ /
Exposures from the direct exposure pathway should not be added to those from the indirect
pathways. This is because the risk from the direct exposure pathway, which results from the
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DRAFT April 15, 1994
inhalation route of exposure, is determined separately from the risk from the indirect pathways,,
which result from the oral route of exposure. However, for carcinogens, the risk from direct
exposures to a constituent is added to the risk from indirect exposures to the constituent for each
exposure scenario. ' "
Additivitv nf rrmstitnents Within an Exposure Scenario
The exposure scenarios described in Section 2.3 involve exposures to a variety of
constituents. For the purpose of the screening analysis, cancer risks from carcinogenic
constituents are added together to estimate the total carcinogenic risk. However, hazard
quotients for noncarcinogens should be added together only if the health effects caused by
exposure to the constituents are similar (e.g., the constituents affect the same target organ).
Specific guidance regarding the additivity of hazard quotients for different constituents and the
calculation of hazard indices via the oral route of exposure (i.e., from indirect exposures) is
provided in Section 6. s
C-2-9
-------
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DRAFT
April 15, 1994
3. AIR DISPERSION AND DEPOSITION MODELING
\ " . , { " -, . .
The COMPDEP air dispersion arid deposition model (version 93340) is used to/estimate
air concentrations, and wet and dry deposition rates. The model FORTRAN code, executable
versions, sample input and output files, and documentation are available for downloading from
the Support Center for Regulatory Air Models bulletin board system (SCRAM BBS) in the Other
Models section. The SCRAM BBS is a part of the Office of Air Quality Planning and Standards
Technology Transfer Network (OAQPS TTN). Accessing information for SCRAM is contained
hi the table box. A description of the model is provided with the model package.
Resources for Model Code
COMPDEP model
PCRAMMET
meteorological
preprocessor
Precipitation
preprocessor (not
yet available)
OAQPS' Support Center for
Regulatory Air Models Bulletin
Board System (SCRAM BBS)
Other Models section
In the first call the user
provides registration
information. Once registered,
the user has full access to the
BBS.
(919) 541-5742
24 hrs/day, 7 days/wk except
Monday a.m.'
1200 - 9600, 14.4K Baud
Line settings: 8 data bits
no parity
1 stop bit
Terminal emulation: VT100 or ANSI
System operator: (919)541-5384
(normal business hours EST)
Three input, files are vised for COMPDEP. The control file (*.INP). is an ASCII file
which contains the model option settings, source parameters, and receptor locations. Two
binary, format meteorological input files are also used. The meteorological file (*.MET)
contains hourly values of wind speed, wind direction, stability class, mixing height, and
ambient air temperature. The precipitation file (*.PPT) contains hourly values of precipitation
type and intensity. , ,
The output available from COMPDEP includes the-long-term average air concentration
for each receptor hi units of ug/m3, and the long-term average values for each receptor of dry
deposition, wet deposition, and combined wet and dry deposition in units of g/m -yr.
The averages are taken over the period of record of the meteorological data, as input to the
model. If one year of meteorological data are input, the values at each receptor will be annual
averages. The model output identifies the highest value of air concentration, dry deposition,
wet deposition, and combined wet and dry deposition and the associated receptor. The model
C-3-1
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DRAFT
April 15, 1994
output also provides the arithmetic average value across all receptors of air concentration, dry
deposition, wet deposition, and combined wet and dry deposition.'
3.1 Control File
This section discusses the control file (*.INP) and provides default values for the
parameters which are not facility or site-specific. The user's instructions provided with the
COMPDEP model code contain more,detailed information on using the model. Table 3.1 lists
all of the inputs required for running COMPDEP, including recommended default values.
Table 3.1 Inputs for COMPDEP Modeling
, Variable
Horizontal scale factor
Vertical scale factor
Pollutant half-life
Input
0.001
1.0
0.0
Units/Explanation
converts horizontal units to kilometers
converts vertical units to meters
no pollutant decay, (seconds)
Modeling options:
Terrain adjustment
Stack tip downwash
Plume rise
Buoyancy induced dispersion
Calms processing
Dry deposition
Wet deposition
Building wake effects
Anemometer height
Array of wind speed profiling factors
Array of terrain adjustments
Distance limit for plume centerline
Building height
Building width
1
0
. 0
1
1
1
1
1
10,0
0.07,0.07,0.1,
0.15, 0.35, 0.55
0.5, 0.5, 0.5, 0.5,
0.0, 0.0
10.0
facility-specific
facility-specific
use terrain adjustment
use stack tip downwash
calculate distance dependent rise ..
use buoyancy induced dispersion
use calms processing routine
use dry deposition
use wet deposition
include building wake effects
meters
adjustments for Pasquill-Gifford stability
classes A through F, unitless
adjustments for Pasquill-Gifford stability
classes A through F, unitless
meters
meters
meters
1 The model also computes a geometric mean value which takes .the logarithm of the concentration and deposition
values. The geometric mean should not be used in place of the arithmetic average for estimating areal average
deposition. The use of areal average deposition is discussed in Section 3.5, Receptor Placement.
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DRAFT
AprU 15, 1994
Table 3.1 Inputs for COMPDEP Modeling
Variable
Source coordinates
Stack height
Stack gas exit temperature
Stack inner diameter
Stack gas exit velocity
Ground elevation at stack
Particle Size categories
Particle density
Array of particle size classes
Fraction of emissions in each particle
Receptor locations - 1 st run
Name
X (east) coordinate
Y (north) coordinate
Height above ground
Ground elevation -
Input
0.0, 0.0
, facility-specific
facility-specific
facility-specific
facility-specific
site specific
3 '.-
1.0
1.0 6.0 15.
1.0
.78 .19 ,.03
optional
See Table 3.3
See Table 3.3
0.0
0.0 or terrain
height
Receptors - watershed - 2nd run
Name
X (east) coordinate
Y (north) coordinate
Height above ground
Ground elevation
optional
default or site
specific
default or site
specific
0.0
0.0 or terrain
height
Units/Explanation
s--!^=:^ss
^^^^^^^^^^^^-^^^ : ~~
X, Y coordinates of stack in meters
meters
degrees kelvin
meters
meters/second
meters
See Section 3.6, Terrain
number of categories, unitless
grams/cubic centimeter
mean particle diameter, microns
grams/second -
fraction of emissions in particle size
class by surface area, unitless
Polar array along 22.5° radials, spaced
at logarithmic intervals out to 1 0,000 m
from the stack, converted to Cartesian
coordinates (X, Y values).
See Section 3.5, Receptor Placement
Sfee Section 3.6, Terrain
If using the default watershed, place
receptors spaced every 500 m over a
7000 m x 7000 m square centered on
the maximum combined deposition
receptor from the 1st run.
Jf using the actual watershed, place
the boundaries of the watershed at the
actual location of the watershed.
See Section 3.5, Receptor Placement
See Section 3.6, Terrain
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DRAFT
April 15, 1994
Table 3.1 Inputs for COMPDEP Modeling
Variable
Surface roughness length
Precipitation scavenging coefficients
Input
See Table 3.4
Particle Size
U/m)
1
6
15
Units/Explanation
See Section 3.8, Surface Roughness
Precipitation Intensity
light
(s-1)
2.20E-4
1 .80E-4
9.69E-3
moderate
(s-1)
5.60E-4
8.93E-4
9.69E-3
heavy
(s-1)
1.46E-3
4.64E-3
9.69E-3
The sample input file which is downloaded with the model (EXAMPLE.INP) can be used
as a starting point when developing the control file. Example 3.1 illustrates the control file as
it should be prepared for the screening analysis. The input parameters which should be
replaced by facility-specific or site-specific values are italicized hi Example 3.1.
The changes that should be made to the EXAMPLE.INP file are as follows:
1) TRANSITIONAL PLUME RISE: This option should be set to 0 so that transitional
plume rise will be calculated when the terrain heights exceed the top of the stack.
(COMPDEP defaults to using the transitional .plume rise when the building
downwash algorithm is selected.)
2) STACK AND BUILDING PARAMETERS: Facility-specific values for stack
height, stack diameter, exit temperature, and exit velocity are required. Also
required are facility-specific values for building height and building width.
3) RECEPTOR LOCATIONS: The recommended receptor locations are discussed in
Section 3.5.
4) RECEPTOR ELEVATIONS: Site-specific terrain elevations (and stack base
elevation) are needed hi areas of complex terrain or where other terrain features are
significant, as discussed in Section 3.6.
5) PARTICLE SPECIFIC INPUTS: The recommended particle size categories,
fraction of emissions in each category, and particle density are listed in Table 3.2.
Table 3.2 summarizes the changes to the EXAMPLE.INP file.
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DRAFT
April 15, 1994
Example 3.1 COMPDEP input file for the screening analysis. Inputs in bold
'. italics are replaced by facility or site specific values.
EXAMPLE RUN OF COMPDEP FOR COMBUSTION STRATEGY SCREENING ANALYSES
RECEPTORS AT DEFAULT LOCATIONS (O'N RADIALS AT 22.5 DEGREE INTERVALS)
MODELING FOR AIR CONCENTRATIONS. AND DRY 'AND WET DEPOSITION FLUXES
89,l,i, .001,1.0,0. ,0
1,0,0,1,1,1,1,1 , .
10, .07,.07, .1, .15, .35, .55, .5, .5, .5, .5,0.,0.,10.,20.,30.
0.,0.,25.,400.,1.5,10. ,0. ,3,1.0
UNIT EMISSIONS ': .1. ' ..''":.-. .
0,78,0.19,0.03
ENDP
0,100 0. 100.
22,100 ; 38. 92.
45,100 71- 71-
67,100 92. 38.
90,100 100. 0.
.112,100 92. -38.
135,100 71. ; -71.
157,100 38. -92.
180,100 0. -100.
202,100 -38. -92.
225,100 -.-71. -71.
247,100 . -92. ' -38.
270,100 -100. 0.
292,100 , -92. . 38.
315,100 -71. 71. .
337,100 -38. 92. ,
0,150 0. " 150.
22,150 57.t .139.
45,150 106. 106.
67,150 139. . ' 57.
90,150 ' 150. 0.
0 .
0 . - ;"
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0 .
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
247,9999 -9239.
270,9999 -10000.
292,9999 -9239.
315,9999 . -7071.
337,9999 -3827.
ENDR ,
0.3
2.20E-4,5.60E-4,1.46E-3
1.80E-4,8.93E-4,4.64E-3'
9..69E-3,9.69E-3,9.69E-3
-3827-.
0.
3827.
7071.
9239.
0.
0.
0.
0.
0.
0.
0.
0.
0.
0.
Note: See Table 3.2 on the highlighted changes required.
C-3-5
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DRAFT
April 15, 1994
Table 3.2 Changes from EXAMPLE.INP for Screening Analysis
Variable
Title - 3 lines
Starting year
Plume rise
Building height
Building width
Stack height
Stack temperature
Stack diameter
Stack gas exit velocity
Stack ground level
Particle density
Array of particle sizes
Fraction of emissions in
each particle class
Receptor locations and
ground elevations
Surface roughness
Variable Name *
LINE1, LINE2, LINES
IDATEd )
IOPT(3)
HB
WB
SOURCE(3)
SOURCE{4)
SOURCE(5)
SOURCE(6)
ELP
PARTDNS
PARTSZ
PFRACT
RREC,SREC,ELR
ZO
Screen Value
facility-specific
site specific
0
facility-specific
facility-specific
facility-specific
facility-specific
facility-specific
facility-specific
facility-specific
1.0
1., 6., 15.
.78, .19, .03
polar array out to
10km
Cartesian
coordinates
See Table 3.6
Also site specific
(optional)
site specific
EXAMPLE.INP
EXAMPLE RUN FOR
COMPDEP....
89
1
20.0
30.0
25.0
400.0
1.5
10.0
0. ^
1.8
1., 6.78, 20.
.85, .10, .05
polar array out
to 50 km
Cartesian
coordinates
0.3
Units
i
2-digit
meters
meters
meters
degrees K
meters
meters/sec
meters ,
g/cm3
size range median,
fim
unitless
meters
meters
* See COMPDEP documentation which accompanies the model code.
3.2 Meteorologic Data
It is important that appropriate meteorological data be used. Data from nearby weather
stations should be evaluated to determine which data are most representative of conditions at
the site. The Guideline on Air Quality Models (EPA, 1993b) recommends that five years of
meteorological data be used for making long-term estimates of ambient air concentrations. If
five years of data are not available, as many years of complete data as are available should be
used. A minimum of one year of data is required.
Required meteorological surface observations include hourly wind speed, wind direction,
ambient temperature, cloud cover, and precipitation type and amounts. Also required are
C-3-6
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\ .
DRAFT
AprU 15, 1994
Resources for Meteorological Data
Meteorological
data
National Climatic Data
Center (NCDC),
Asheville, NC
File type:
Hourly precipitation amounts' -. .
Hourly surface observations with precipitation type
Twice daily mixing heights from nearest station
National .Climatic Data Center
Federal Building
37 Battery Park Avenue
Asheville, NC 28801-2733
Customer Service: (704)271-4871
File name:
NCDC TD-3240 ;
NCDCTD-3280
NCDC TD-9689
(also available on SCRAM BBS for
1984 through 1991) .
estimates of day and nighttime "(twice daily) mixing heights. Unless more representative data
are available, the most common source of meteorological data is the National Climatic Data
Center (NCDC) in Asheville, NC. Information is given in the text box on how to contact
NCDC for meteorologic information. The twice daily mixing height files are available on
SCRAM for the years 1984 to 1991 for National Weather Service (NWS) locations which take
routine upper air soundings. Local effects are less pronounced hi upper air soundings, and
given the large spacing between stations taking soundings, data from the closest upper air
station should normally be used.2 .
Preprocessors (PCRAMMET or MPRM) for formatting the second input file (*.MET)
required for COMPDEP are available for downloading from SCRAM. The data inputs for these
preprocessors are hourly values of wind speed, wind direction, ambient temperature, sky cover,
and twice daily mixing heights. The preprocessor creates a file in binary .format which contains
hourly wind speed, wind direction (randomized), atmospheric stability class, temperature, and
mixing height.
o , ' | .
A precipitation file which couples the type of precipitation from the surface observations
with the amount of precipitation observed is the third input file (*.PPT) required for
COMPDEP, a file which is also hi binary format. The information in the text box specifies the
type of data'required to prepare the precipitation file. The data are available through the NCDC
2 NWS surface data are available on SCRAM; however, these files have been shortened and the precipitation type
has been deleted. Therefore, these files cannot be used for preparing .the precipitation file (*.PPT) for input to the
COMPDEP model. . - ' ' ' '
C-3-7
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DRAFT April 15, 1994
for NWS and other locations which routinely take weather observations. The documentation in
the COMPDEP model package contains instructions for preparing the inputs for the precipitation
file-3
3.3 Emission Rates
For the screening analysis, the model is run once using a "unit" emission rate of
1 gram/second, with both dry and wet deposition options selected. No distinction is made
between particles and vapors for the COMPDEP model run. This is a conservative, simplifying
assumption. The results of this run are used for both air concentrations and deposition rates of
particles and vapors. Adjustments to the modeled air concentration and deposition to account
for the vapor-particle split are made at the 'point of exposure. This is done in the pathway
equations in Section 4 using the chemical specific data provided hi Section 5.
The values obtained with the unit emission rate are adjusted to chemical specific air
concentrations and deposition rates using chemical specific emissions rates. Since the
relationship between emissions and air concentrations and deposition rates is linear, the air
concentrations and deposition rates resulting from the unit emission rate can be multiplied by the
actual emission rate of each chemical to obtain the chemical specific concentrations and
deposition rates. ,
Chemical Air Concentration Modeled Air Concentration
Chemical Emission Rate Unit Emission Rate (1 g/s)
Since the unit emission rate = 1,. this reduces to: , ,
Chemical Air Concentration = Chemical Emission Rate * Modeled Air Concentration
Similarly, the chemical specific deposition is calculated as follows:
Chemical Deposition = Chemical Emission Rate * Modeled Deposition (wet&dry combined)
3.4 Exposure Locations
The locations of the maximum combined wet and dry deposition and the maximum air
concentration, as output by the COMPDEP model, are used hi the screening analysis as the
initial point of departure for all indirect exposures. However, for the subsistence fanner or
subsistence fisher scenarios, a less conservative assumption could be made based on local land
3 A preprocessor for the precipitation files is being developed and will also be available on SCRAM.
C-3-8
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DRAFT ..,".' AprUlS, 1994
use and water resource information. Such information would be examined in order to determine
the actual locations, of agricultural fields, pasture lands, and watersheds of. interest. One
approach would then be to use the maximum combined deposition (wet and dry) from a single
receptor located over the field, pasture, or watershed and the maximum air concentration. For
the subsistence fisher scenario, a more refined approach would be to locate the actual boundaries
of the watershed to calculate the average combined (wet and dry) deposition over the watershed
instead of using the maximum combined .deposition. These alternative approaches are discussed
further in Section 3.5, Receptor Placement.
"The locations of the maximum combined deposition (wet and dry) and maximum air
concentrations should generally always be used for the residential exposure scenarios unless these
are at locations where it is implausible that a residence could be located (e:g., over a lake or a
large industrial area). In this case, the highest combined deposition and highest air concentration
from locations where a residence could be located should be used. This could be on the
shoreline of a lake, on currently vacant land beyond the facility or industrial area, or at the
location of a current residence. ,
Similarly, the location of the maximum air concentration, as output by the COMPDEP
model, is used in the screening analysis as the initial point of departure for all direct exposures.
Direct'inhalation exposures are estimated from the maximum air concentration. For the purpose
of characterizing risk, the maximum air concentration is assumed to.be collocated with the point
of maximum combined deposition. However, as discussed above, for the subsistence farmer or
subsistence fisher scenarios, a less conservative assumption could be made based on local land
use or water resource information; Such information would be used to determine the actual
locations of agricultural fields, pasture lands, and watersheds of interest. In this case, the
maximum air concentration from a single receptor located over the field, pasture, or watershed
would be used hi the screening analysis. . :
3.5 Receptor Placement
As downloaded from the SCRAM BBS, the COMPDEP model limits the number of
receptors to 500. Impacts of emissions are generally higher closer to the source. Due to the
need to locate the maximum impact (within the constraints of the model), the receptors are
spaced at logarithmic intervals from 100 meters to 10 kilometers from the source.4
For the screening analysis, a default polar array of receptors along 16 radials spaced every
22 5° is used in the initial COMPDEP run. The receptors are spaced at distances of 100, 150,
200, 300, 400, 500, 700, 1000, 1500, 2000, 3000, 4000, 5000, 7000, and 10000 meters from
the 'stack. The COMPDEP model run with these receptors provides the maximum air.
concentration and combined deposition (each from a single receptor) which is used in the
screening analysis. The current version of COMPDEP requires that'the receptors be input in
4 Model results for receptors located closer than 100 meters may not be reliable.
C-3-9
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DRAFT April 15, 1994
Cartesian coordinates. Table 3.3 lists the Cartesian equivalents of the recommended polar array
of receptors.
Site-specific information could be used to identify other receptors which represent the
actual locations of agricultural areas or watersheds. If the actual locations, of agricultural areas
and watersheds are known, the highest values of air concentration and combined deposition from
the set of individual receptors that lie within the boundaries of the area would be used in place
of the maximum values from the entire array of receptors.
For large watersheds, a second COMPDEP model run could be performed. This run
would use a new array of receptors. The new array would cover the area of the watershed of
interest only, with receptors placed on a Cartesian grid at 500 meter intervals over the entire
area. For the purpose of assessing indirect exposures, the areal average air concentration and
areal average combined deposition from all receptors for this new model run would be used
rather than the highest values from the set of individual receptors that lie within the watershed
boundaries (as from the initial model run). COMPDEP automatically calculates the average
"hourly" air concentration across all receptors and the average combined deposition across all
receptors. *' . "
When local land use information is not available, the original array of receptors could be
replaced in a second COMPDEP run by a default watershed. The grid of receptors would be
centered on the point of the maximum combined deposition, as determined from the initial model
run. For the default watershed, the array of receptors would cover an area of 7000 meters by
7000 meters with the receptors placed on a Cartesian grid at 500 meter intervals.5 The average
"hourly" air concentration across all receptors and the average combined deposition across all
receptors, as calculated by the model, would be used rather than the highest values from the set
of individual receptors that lie within the watershed boundaries (as from the initial model run).
5 The default watershed has an area of, 5000 hectares, a value representing the 10th percentile of a national
distribution of watershed areas.
C-3-10
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DRAFT
April 15, 1994
Table 3.3 Conversion of Polar Receptor Array to Cartesian Coordinates
Azimuth
<°>
0.0
22.5
45.0
67.5*
90.0
112.5
135.0
157.5
1 SO'.O
202.5
225.0 ,
247.5
270.0
292.5
315.0
337.5
0.0
22.5
45.0
67.5
90.0
112.5
135.0
157.5
180.0
202.5
225.0
, 247.5
270.0
Radius
(m)
100
100
100
1 00
100
100
100
TOO
100
ioo
100
100
100
1 00
100
100
150
1 50
150
150
150
150
150
150
150
150
150
1 50
150
X
(m)
0
38
71
92
.100
92
71,
38
0
-38
-71
-92
100
-92
-71
-38
0
57
106
139
150
139
106
57
O
-57
v106
-139
-150
Y
-------
DRAFT April 15, 1994
.t
Table 3.3 Conversion of Polar Receptor Array to Cartesian Coordinates
Azimuth
(°)
225.0
247.5
270.0
292.5
315.0
337.5
0.0
22.5
45.0
67.5
90.0
112.5
135.0
157.5
180.0
202.5
225.0
247.5
270.0
292.5
315.0
337.5
0.0
22.5
45.0'
67.5
90.0
112.5
135.0
Radius
(m)
300
300
300
300
300
300
400
400
400
400
400
400
400
400
400
400
400
400
400
400
400
400
500
500
500
500
500
500
500
X
(m)
-212
-277
-300
-277
-212
-115
0
153
283
370
, , ' 400
370
283
153
0
-153
-283
-370
-400
-370
-283
-153
0
191
354
462
500
462
354
y
(m)
-212
-115
0
115
212
277
400
370
283
153
0
-153
-283
-370
-400
-370
-283
-153
0
153
283
370
500
462
354
191
0
-191
-354
Azimuth
(°)
157.5
180.0
202.5
225.0
247.5
270.0
292.5
315.0
337.5
0.0
22.5
45.0
67.5
90.0
112.5
135.0
157.5
180.0
202.5
225.0
247.5
270.0
292.5
315.0
337.5
0.0
22.5
45.0
67.5
Radius
(m)
500
500
500
500
500
500
500
500
500
700
700
700
700
700
700
700
700
700
700
700
700
700
700
700
700
1000
1000
1000
1000
X
(m)
191
0
-191
-354
-462
-500
-462
-354
-191
0
268
495
647 .
700
647
495
268
0
-268
-495
-647
-700
-647
-495
-268
0
383
707
924
Y
(m)
-462
-500
-462
-354
-191
0
191
354
462
700
647
495
268
0
-268
-495
-647
-700
-647
-495
-268
0
268
495
647
1000
924
707
383
C-3-12
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DRAFT
April 15, 1994
. .
Table 3.3 Conversion of Polar Receptor Array to Cartesian Coordinates
Azimuth
(°)
90.0
112.5
135.0
157.5
180.0
202.5
225.0
247.5
270.0
292.5
315.0
337.5
0.0
22.5
45.0
67.5
90.0
112.5
135.0
157.5
1 80.0
202.5
225.0
247.5
270.0
292.5
315.0
337.5
0.0
Radius
(m)
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1000
1500
1500
1500
1500
1500
1500
1500
1500
1500
1500
1500
1500
1500
1500
1500
1500
2000
X
(m)
1000
924
707
383
0
-383
-707
-924
-1000
-924
-707
-383
0
574
H061
H386
1500
1386
1061
574
0
-574
-1061
-1386
-1 500
-1386
-1061
-574
0
Y
(m)
0
-383
-707
-924
-1000
-924
-707
-383
0
383
707
924
1500
1386
1061
574
0
-574
-1061
-1386
-1500
-1386
-1061
-574
0
574
1061
1386
2000
Azimuth
(«)'.
22.5
45.0
67.5
90.0
112.5
135.0
157.5
180.0
202.5
225.0
247.5
270.0
292.5
31 5.0
337.5
0.0
22.5
45.0
67.5
90.6
112.5
135.0
157.5
180.0
202.5
225.0
247.5
270.0
292.5
Radius
(m)
2000
2000
2000
2000.
2000
2000
200O
2000
2000
2000
2000
2000
2000
2000
2000
3000
3000
3000
. 3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
3000
X
(m)
765
1414
1 848
2000
1848
1414
765
.0
- -765
-1414
-1 848
-2000
-1848
-1414
-765
0
1148
2121
2772
3000,
2772
2121
1148
0
, -1148
-2121
-2772
-3000
-2772
- Y
(m)
' 1848
1414
765
0
-765
-1414
-1848
-2000
-1848
-1414
-765
0
765
1414
1848
3000
2772
2121
1148
0
-1148 ,
-2121
-2772
, -3000
-2772
-2121
-1148
0
1148
C-3-13
-------
DRAFT
April 15, 1994
Table 3.3 Conversion of Polar Receptor Array to Cartesian Coordinates
Azimuth
(°)
315.0
337.5
0.0
22.5
45.0
67.5
90.0
112.5
135'.0
157.5
180.0
202.5
225.0
247.5
270.0
292.5
315.0
337.5
0.0
22.5
45.0
67.5
90.0
112.5
135.0
157.5
180.0
202.5
225.0
Radius
(m)
3000
3000
4000
4000
4000
4000
4000
4000
4000
4000
4000
4000
4000
4000
4000
4000
4000
4000
5000
5000
5000
5000
5000
5000
5000
5000
5000
5000
5000
X
(m)
-2121
-1148
0
1531
2828
3696
4000
3696
2828
1531
0
-1531
-2828
-3696
-4000
-3696-
-2828
-1531
0
1913
3536
4619
5000
4619
3536
1913
0
-1913
-3536
Y
(m)
2121
2772
4000
3696
2828
1531
0
-1531
-2828
-3696
-4000
-3696
-2828
-1531
0
1531
2828
3696
5000
4619
3536
1913
0
-1913
-3536
-4619
-5000
-4619
-3536
Azimuth
(°)
247.5
270.0
292.5-
_315.0
337.5
0.0
22:&
45.0
67.5
90.0
112.5
135.0
157.5
180.0
202.5
225.0
247.5
270.0
292.5
315.0
337.5
0.0
22.5
45.0
67.5
90.0
112.5
135.0
157.5
Radius
(m)
5000
5000
5000
5000
5000
7000
7000
7000
7000
7000
7000
7000
7000
7000
7000
7000
7000
7000
7000
7000
7000
10000
10000
10000
10000
1 0000
10000
10000
10000
\
X
(m)
-4619
-5000
-4619
-3536
-1913
0
2679
4950
6467
7000
6467
4950
2679
0
-2679
-4950
-6467
-7000
-6467
-4950
-2679
0
3827
7071
9239
10000
9239
7071
3827
- Y
(m)
-1913
0
1913
3536
4619
7000
6467
4950
2679
0
-2679
-4950
: -6467
-7000
-6467
-4950
-2679
0
267.9
4950
6467
10000
9239
7071
3827
0
-3827
-7071
-9239
C-3-14
-------
DRAFT
April 15, 1994
Table 3.3 Conversion of Polar Receptor Array to Cartesian Coordinates
Azimuth
(°)
180.0
202.5
225.0
247.5
270.0
292.5
315.0
337.5
Radius
(m)
10000
10000
1 0000
10000
10000
10000
10000
10000
X
(m)
0
-3827
-7071
-9239
-10000
-9239
-7071
-3827
Y
(m)
-1 0000
-9239
-7071
-3827
0
3827
7071
9239
Azimuth
(°)
'
_
Radius
(m)
X
(m)
Y
(m)
,.
>
3.6 Terrain
Terrain inputs for the source and each receptor are required in areas of complex terrain.
For the screening analysis, actual, terrain elevations must be used if the terrain rises as high as
the top of the stack within about 5 kilometers of the stack. For areas with terrain which remains
below the top of the stack; the use of site-specific terrain heights is not essential. In this case
flat terrain could be assumed. However, the use of actual terrain heights may be desirable in
areas with significant terrain features even though the terrain remains below stack top within
5 kilometers. ' : .
Terrain elevation heights can be obtained from U.S. Geologic Survey topographic maps.
The appropriate USGS topographic maps should be acquired for the area surrounding the facility
hi order to evaluate whether or not a terrain adjustment is necessary. Local USGS topographic
maps are available from the USGS office located hi each State, through local blueprint and map
supply shops, or from the USGS Map Distribution Center hi Denver, Colorado.
3.7 Determining Watershed Area
The total watershed surface area that is affected by deposition an^ that drams to the body
of water can be quite extensive. Therefore, it is important to consider the hydrology of the
watershed itself. Water and sediments hi a waterbody may originate from watershed runoff and
soils that are (or could be) significantly impacted by combustion emissions as well as watershed
runoff and soils that are relatively unaffected. If a combustion source is depositing principally
on a land area which feeds a tributary of a large river system, then the assessor should consider
what might be termed an "effective" area. An "effective" area will almost always be less than
the total area of the watershed. A "watershed" contains all the land area which contributes water
C-3-15
-------
JRAFT April 15, 1994
to a river system. For large river systems, this area is on the order of thousands of square miles
and can include any number of tributaries and smaller streams feeding into the main branch of
the river. Each stream and tributary has its own drainage area. If the area which is most
strongly impacted by combustion emissions can be ascertained to lie within such a drainage area,
then it would be appropriate to assign watershed area based on the drainage area size.
i ' . -
Another important consideration is whether or not the water body in question supports or
could support a significant fishery resource. In general, it may be most efficient for the assessor
to identify water resources that support subsistence or recreational fishing and then to focus on
the smallest drainage area that feeds those water resources which is closest to the facility and
could itself support fishing activities. .. .
Another consideration for determining watershed area is the location of the facility with
respect to the point where fish are caught for consumption. If this point is far upstream in the
watershed relative to the location of the facility, there may be little reason to think that
sediments or water near where fish are caught are significantly impacted by the combustion
source. However, if this point is downstream from the facility, then sediment and water quality
near where fish are caught could^be affected. In this instance, points further downstream from
where fish are caught (e.g., at the bottom of the watershed) may not be of interest. If this is
the case, land draining into these downstream areas should not be part of the "effective"
drainage area. ' /
For a standing waterbody such as a lake or pond, the watershed area should be the area
around the lake or pond which contributes runoff and sediments to the waterbody and, as in the
above discussion on river systems, a part of the land area contributing runoff and sediments to
streams or rivers which may feed the lake or pond.
Local topographic maps, land use information, and State game and fish commissions may
be of help hi determining the appropriate size and location of the watershed.
Due to the inherent limitations of the COMPDEP model, receptors should not be placed
beyond 50 kilometers from the stack. Therefore, watershed areas that extend beyond
50 kilometers from the facility need not be considered hi the screening analysis.
3.8 Surface Roughness
The surface roughness is a reflection of the land use over the region. Surface roughness
measures the variations in the height of the individual surface elements. The value is used to
characterize the turbulence which results hi deposition at the ground surface. Table 3.4 lists the
roughness heights which can be used as input to the COMPDEP model. These values are based
on the general land use hi the vicinity of the stack (or within the area over which deposition is
a concern).
C-3-16
-------
DRAFr April 15, 1994
* ' " ' ' ' * ' - s -
Table 3.4 Typical Surface Roughness Lengths for Various Land Use Types
Land Use
Urban - Commercial/Industrial
Common residential - single family dwellings
Compact residential - multi-family dwelling
Metropolitan natural (parks, golf courses)
Agricultural - rural
Semi-rural
,»' , -
Undeveloped, wasteland
Forest
Bottomland agricultural
Typical Roughness Length
(centimeters)
200
20
50
15
20
20
' ' ' 5 ' '
100
15
(meters)
2.0
0.20
0.5
,0.15
0.20
- 0.20
0.05
' 1.0
0.15
All values from U.S. EPA, 1993a.
C-3-17
-------
-------
DRAFT :.-.' Aprill5,1994
4. INDIRECT EXPOSURE PATHWAY EQUATIONS
j !' ' , . . - -
This section presents the equations that are used in the screening analysis to calculate media
and food concentrations of contaminantsi'for the indirect exposure pathways. Values are
provided for parameters that are not chemical or site-specific. The chemical-specific parameter
values are presented in table format in Section 5.
The individual equations are organized into five overall pathway groupings that are related to
human ingestion of media and food. These are as follows: 1) soil ingestion; 2) consumption of
above-ground vegetables; ; . . ' . ;. ,
3) consumption of root vegetables; "^'^^"^ll^^ll^lll^ll"^il1*
4) consumption of beef and milk;
and 5) fish consumption. Each Section 4.1 Soil Ingestion
group is discussed hi a separate Section 4.2 Consumption of
section as indicated in the text Above-ground Vegetables
box. In each section, all equations Section 4.3 Consumption of Root
for calculating contaminant Vegetables
concentrations for the individual Section 4.4 Consumption of Beef and
pathways in the group are Milk
provided in table format. The Section 4.5 Consumption of Fish
introduction to each section
provides a brief discussion of what . . - ;' "' '.
the equations do, which aspects of "^^M^BI^MB
the calculations have been omitted , ; ,
from the screening analysis, and which exposure scenarios the group of calculations applies to.
The introduction also identifies which two input parameters that have been set to high end values
for that pathway group. Guidance is also provided on setting site-specific input parameters
where site-specific values are needed.
Tables 4.0.1 and 4.0.2 are provided for easy reference. Table 4.0.1 identifies whicb,equatipns
are used for each exposure scenario. Table 4.0.2 identifies which equations are used for each
chemical. . ,
Each equation is presented in table format. The tables show the equations, identify the
exposure scenarios and constituents for which the equations are to be used, list all input
parameters, and provide default values as appropriate. The default Value column of the tables.
may contain one of the following designations instead of (or hi addition to) a default value:
shaded, no value: this signifies that this row of the table describes either the |,^rameter
being calculated by the given equation or a units conversion constant in the equation.
modeled (see Sec. 3): this indicates a deposition rate or air concentration, as determined
by COMPDEP model, as described in Section 3.
calculated (see Table 4.x.x): this indicates that an equation is given for calculating the
parameter in the indicated table.
C-4-1
-------
DRAFT
April 15, 1994
site-specific: this indicates that the parameter is site-specific and that no default value is
considered appropriate.
High end: value: this indicates that the parameter is one of two parameters that have
been set to high end values for the pathway grouping.
For parameters that are marked site-specific, the user must determine an appropriate site-specific
value. Guidance is provided hi the introductory sections to each pathway grouping on setting
values for site-specific parameters.
If site-specific data are used instead of the default value for setting a value for a parameter that
is indicated in the tables as being set to a high end" value, a high end site-specific value should
be used. This may be a 90th percentile value or a 10th percentile value, depending on the
parameter. The appropriate percentile is indicated hi the introduction to each section.
Table 4.0.1. Summary of Screening Equation Use by Scenario
Table
Pathway Component
Scenario
Subsistence
Farmer
Subsistence
Fisher
Adult
Resident
Child
Resident
Soil Ingestion Pathway '.'-'.''''.' \'-:' . , .;- 'iV. .'.'"", '.; :"..".. .;^y :"?'.".'' .' ::-''. "';','''
4.1.1
4.1.2
Deposition to Soil
Soil Loss Constant
/
S
/
J
S
S
/
/
Above-ground Vegetable Pathway ::.;;:!; : .' : . - V1 '.;-'<; :; :. :
4.2.1
4.2.2
Above-ground Vegetable Concentration
from Deposition
Above-ground Vegetable Concentration
from Direct Air-to-Plant Transfer
S
s
S
/
S
s
S
V
Root Vegetable Pathway . '.'- ' '; ,'V. *;': -/''. ' ': - '' " '- : '''''".. ;. '. ' '"'-.' '" ' ''"', ''''''- ":i"" :":/' :r- '":" f::
4.3.1
4.3.2
Deposition to Soil
Root Vegetable Concentration from
Root Uptake
S
s
S
S
s
s
s
s
Beef and Milk Pathways '' ' ;-' .'..,.',".;'' v":v''! .':v;; '.*,:' ,'"'.:'.'.' ."!> :';.'" ',-''' ' ."'..-." '.' '" [- iv- /.'- "
4.4.1
4.4.2
4.4.3
4.4.4
4.4.5
Deposition to Soil
Above-ground Plant Concentration
from Deposition
Above-ground Plant Concentration
from Direct Air-to-Plant Transfer
Beef Concentration from Ingestion of
Above-ground Plants and Soil
Milk Concentration from Ingestion of
Above-ground Plants and Soil
s
s
s
s
s
C-4-2
-------
DRAFT April IS;
& i '" "..
Table 4.0.1. Summary of Screening Equation Use by Scenario
Table
^^i
Fish Path
4.5.1
4.5.2
4.5.3
4.5.4
4.5.5
4.5.6
4.5.7
4.5.8
4.5.9
4.5.10
4.5.1 1
4.5.12
4.5.13
4.5.14
4.5.15
4.5.16
Pathway Component
Mi^MMMH«MH"»^
Deposition to Watershed Soil
Waterbody Load
Deposition to Waterbody
Universal Soil Loss Equation
Sediment Delivery Ratio
Waterbody Concentration
Fraction in Water Column and
Sediment
Total Water Column Concentration
Dissolved Water Concentration
Bed Sediment Concentration
Fish Concentration from Dissolved
Fish Concentration from Total Water
Fish Concentration from Bed Sediment
Concentration
Scenario
Subsistence
Farmer
.
=====
Subsistence
Fisher
/
S
/
S
/
V
S
s
S
s
/
/
/
^
/
/
Adult
Resident
=^^===j_
Child
Resident
C-4-3
-------
DRAFT
April 15, 1994
Table 4.0.2. Summary of Screening Equation Use by Chemical
Table
Pathway Component
Arsenic
Beryllium
Benzo(a)
pyrene
Bis
|2-ethyl
hexyl)
phthalate
1 ,3-Dinitro
benzene
Soil Ingestion Pathway
4.1.1
4.1.2
Deposition to Soil
Soil Loss Constant
/
/
/
/
/
2,4-Dinitro
toluene
/
2,6-Dinitro
toluene
/
Di(n)octyl
phthalate
/
Above-ground Vegetable Pathway
4.2.1
4.2.2
Above-ground Vegetable Concentration
from Deposition
Above-ground Vegetable Concentration
from Direct Air-to-Plant Transfer
/
/
/
/
" /
/
/
/
/
/
/
/
/
/
Root Vegetable Pathway
4.3.1
4.3.2
Deposition to Soil
Root Vegetable Concentration from
Root Uptake
.S
/
/
/
/
/
/
/
/
/
,'
/
/
/
/
/
Beef and Milk Pathways V: ; ;
4.4.1
4.4.2
4.4.3
4.4.4
4.4.5
Deposition to Soil .
Above-ground Plant Concentration from
Deposition
Above-ground Plant Concentration from
Direct Air-to-Plant Transfer
Beef Concentration from Ingestion of
Above-ground Plants and Soil
Milk Concentration from Ingestion of
Above-ground Plants and Soil
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
; /
/
/
/
/
/
/
C-4-4
-------
DRAFT
April 15, 1994
Table 4.0.2: Summary of Screening Equation Use by Chemical
Table
mmtmtm
Fish Path
4.5.1
4.5.2
4.5.3
4.5.4
4.5.5
4.5.6
4.5.7
4.5.8
4.5.9
4.5.10
4.5.1 1
4.5.12
4.5.13
4.5:14
4.5.15
4.5.16
=======================
Pathway Component
=====
Arsenic
way
Deposition to Watershed Soil
Waterbody Load
Deposition to Waterbody
Impervious Runoff Load
Pervious Runoff Load
Erosion Load
Universal Soil Loss Equation
Sediment Delivery Ratio
Waterbody Concentration
Fraction in Water Column and Sediment
Total Water Column Concentration
Dissolved Water Concentration
Bed Sediment Concentration
Fish Concentration from Dissolved
Water Concentration
Fish Concentration from Total Water.
Column Concentration
Fish Concentration from Bed Sediment
Concentration
/
/
/
/
/
/
/
/
- -
i
Beryllium
wmmmmmtm
/
/
/
/
/
/
/
/
Benzo(a)
pyrene
H
/
/
/
/
/
/
/
/
/
=====
'
Bis
(2-ethyl
hexyl)
phthalate
i
/
/
/
/
/
/
/
/
/
=====
=====
1 ,3-Dinitro
benzene.
/
/
/
/
/
/
/
2,4-Dinitro
toluene
/
/
/
/
. /
/
/
/
,
2;6-Dinitro
toluene
' \
: >
/
/
V
S
s
S
/
, I
=====
Di(n)octyl
phthalate
/
/
.
;: ./ -
/
/
/
/
/
:
/
=====
C-4-5
-------
DRAFT
April 15, 1994
Table 4.0.2. Summary of Screening Equation Use by Chemical
Table
Pathway Component
Hexa
chloro
benzene
Lead
Mercury
Nitro
benzene
total PCBs
Penta
chloronitro
benzene
Penta
chloro
phenol
2.3,7,8-
TCDDioxin
Soil Ingestion Pathway
4.1.1
4.1.2
Deposition to Soil
Soil Loss Constant
/
/
/
/
/
/
/
/
/
Above-ground Vegetable Pathway
4.2.1
4.2.2
Above-ground Vegetable Concentration
from Deposition
Above-ground Vegetable Concentration
from Direct Air-to-Plant Transfer
/
/
/
/
Root Vegetable Pathway
4.3.1
4.3.2
Deposition to Soil
Root Vegetable Concentration from
Root Uptake
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
Beef and Milk Pathways .
4.4.1
4.4.2
. 4.4.3
4.4.4
4.4.5
Deposition to Soil
Above-ground Plant Concentration from
Deposition
Above-ground Plant Concentration from
Direct Air-to-Plant Transfer
Beef Concentration from Ingestion of
Above-ground Plants and Soil
Milk Concentration from Ingestion of
Above-ground Plants and Soil
/
/
/
/
/
- ' . :
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
/
, /
/
/
/
/
/
/
/
/
/
/
S
/
/
C-4-6
-------
DRAFT
April 15, 1994
Table 4.0.2. Summary of Screening Equation Use by Chemical
Table
MMMH
Fish Path
4.5.1
4.5.2
4.5.3
4.5.4
4.5.5
4.5.6
4.5.7
4.5.8
4.5.9
4.5.10
4.5.11
4.5.12
4.5.13
4.5.14
4.5.15
4.5.16
\
Pathway Component
way
Deposition to Watershed Soil
Waterbody Load
Deposition to Waterbody
Impervious Runoff Load
Pervious Runoff Load
Erosion Load
Universal Soil Loss Equation
Sediment Delivery Ratio
Waterbody Concentration :
Fraction in Water Column and Sediment
Total Water Column Concentration
Dissolved Water Concentration
Bed Sediment Concentration
Fish Concentration from Dissolved
Water Concentration
Fish Concentration from Total Water
Column Concentration
Fish Concentration from Bed Sediment
Concentration
Hexa
chloro
benzene
Lead
Mercury
Nitro
benzene
/ " ' -
/
/
J
f
/
/
/
/
/
/
/
/
/
/
,
/
/
/
/
/
/
/
/
/
total PCBs
- .' . -
/
/
/
/
/
/
/
/
/
Penta
chloronitro
benzene
/
/
J
. /
/
/
/
Penta
chloro
pltenol
2,3,7,8-
TCDDioxin
/
/
, j *
/
v
/
/
/
/
G-4-7
-------
DRAFT April 15, 1994
4.1 Soil Ingestion
The equations in this section calculate the soil concentration resulting from deposition of
contaminants onto soils at the location of maximum combined (wet and dry) deposition (or an
alternative location, as discussed in Section 3.4, Exposure Locations). Soil contamination by
diffusion of vapors from air has been omitted; instead, for the screening analysis vapors are
treated in the COMPDEP model as particles for the purpose of estimating dry and wet
deposition. The calculation of soil concentration includes a loss term which can account for
loss of contaminant from the soil after deposition by several mechanisms, including leaching,
. erosion, runoff, degradation, and volatilization. These loss mechanisms would all lower the
soil concentration associated with a specific deposition rate. For the screening analysis, the
loss terms for leaching, erosion, runoff, and volatilization have all been set to zero. This will
result in a conservative estimate of soil concentration. The degradation term is
chemical-specific. However, the degradation term is also set to zero for all contaminants
except 'dioxin-like compounds. Note that the elimination of the loss terms may be
inappropriate for certain chemicals for which the screening procedure is not intended
(e.g., volatile organic compounds).
t '.
The soil ingestion pathway is used for all exposure scenarios.
The two high end parameters for soil ingestion are the mixing depth (Z) and the soil bulk
density (BD). Both mixing depth and soil bulk density should be set to 10th percentile (or
low) values. , '
The only site-specific parameter in this pathway is total time of deposition (Tc). This 'should
be set to the expected lifetime of the combustion source (e.g., 30 years).
C-4-8
-------
DRAFT
April 15, 1994
Table 4.1.1. Soil Concentration Due to Deposition
Exposure Scenarios
All
Chemicals
Arsenic
Beryllium '
Benzo(a)pyrene toxicity equivalents
Bis (2-ethylhexyl) phthalate;
1,3-Dinitro benzene .
2,4-Dinitro toluene
..,. ,2,6-Dinitro toluene
"bi(n)octyl phthalate
, Hexachlorobenzene
Lead
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
2,3,7,8-TCDDioxin only:
Sc -Dyd
~
Z -BD -ks
All other chemicals:
[1.6 -exp( -ks Tc)J 100
.y/M
Z -BD
======
Parameter
Sc
Dyd '
Dyw
ks
Tc
100
Z
BD
=======
^ __ __
Definition
Soil concentration of pollutant after total time
period of deposition (mg/kg)
Yearly dry deposition rate of pollutant (g/m2/yr)
Yearly wet deposition rate of pollutant (g/m2/yr)
Soil loss constant (yr1) ,
Total time period over which deposition occurs
(vrs)
Units conversion factor ([mg-m2]/[kg-cm2]j
Soil mixing depth (cm)
Soil bulk density (g/cm3) _^
Description
1
Default Value |]
-':-.' -; ''..-'-''. \..: '' ' .' -.'- '"-.
:---i.';.^-'. ;-;.--. . :". '' :;.'v ' .'. ;
modeled (see Section 3)
modeled (see Section 3)
calculated (see
Table 4.1.2)
site-specific
':' -.-.' , - :-. " ' ' - . -' :' '
:. ' , ". .:- - '. - . " ' '
Hie;:-: end: 1
High end: 1.2
These equations calculate soil concentration as a result of wet and dry deposition onto soil.
Contaminants are assumed to be incorporated only to a finite depth' (the mixing depth, Z). The
first equation should be used when the soil loss term, ks, is not zero; this equation is used only
for 2,3,7,8-TCDDioxin toxicity equivalents. The second equation should be used when ks is
zero (for all other chemicals).
C-4-9
-------
DRAFT
April 15, 1994
Table 4.1.2. Soil Loss Constant
Exposure Scenarios
All
Chemicals
2,3,7,8-TCDDioxin toxicity equivalents
Equation
ks = ksl + kse + ksr +ksg +ksv
Parameter
Definition
Default Value
ks
soil loss constant due to all processes (yr~1)
ksl
loss constant due to leaching (yr"1)
kse
loss constant due to soil erosion (yr1)
ksr
loss constant due to surface runoff (yr"1)
ksg
loss constant due to degradation (yr"1)
chemical-specific
(see Section 5)
ksv
loss constant due to volatilization (yr1)
Description
This equation calculates the soil loss constant, which accounts for the loss of contaminant from
soil by several mechanisms. The loss terms for all mechanisms except degradation are assumed
to be zero.
C-4-10
-------
DRAFT April 15, 1994
4.2 Consumption of Above-ground Vegetables
The equations in this section calculate contaminant concentrations in above-ground vegetables
that are eaten by humans. "
Above-ground vegetables may be contaminated by combustion emissions through several
mechanisms, including direct deposition of contaminants onto the plant, direct uptake of vapor
phase contaminants, and root uptake of contaminants deposited on the soil. For the screening
analysis, root uptake is omitted for above-ground vegetation. Root uptake is typically a much
less important mechanism than direct deposition to the aerial parts of plants. Direct uptake of
vapor phase contaminant is included, as this canjbe -significant for some chemicals. Direct
deposition of particle phase contaminants on the plant is calculated at the location of maximum
combined (wet and dry) deposition (or an alternative location, as discussed in Section 3.4,
Exposure Locations). Direct uptake of vapor phase contaminants is calculated at the location
of maximum air concentration (or an. alternative location, as discussed in Section 3.4).
Because direct uptake of vapor phase contaminants is a form of dry deposition, to insure
conservation of mass the dry deposition rate calculated by the COMPDEP model (Dyd), which
for the screening analysis is used to represent dry deposition of emissions in both the particle
and vapor phases, is adjusted using a. factor that represents the fraction of the chemical hi the
particle phase. Similarly, the ah- concentration calculated by the COMPDEP model, which
represents the total concentration of both airborne particles and vapors, is. adjusted using a
factor that represents the fraction of the chemical in the vapor phase. The fraction in the vapor
phase (Fv) is chemical-specific. The fraction in the particle phase (1 - Fv) is calculated from
the fraction in the vapor phase. ' . , ,
The above.-ground vegetable pathway is used for all exposure scenarios.
The two high end parameters for consumption of above-ground vegetables are the plant
surface loss coefficient (kp) and the crop yield (Yp). The plant surface loss coefficient should
' be set to a 10th percentile (or low) value. Site-specific values of kp may be estimated by;
estimating the length of tune between rainfalls and converting that to yr"1 as follows:
In2
t.J365
ram
where: -..'. . .
(. ^
t. = tune between rainfalls (days)
The time between rainfalls should represent a 90th percentile value, or-longer than the
average value. The crop yield (Yp) should be set to a 10th percentile (or low) value.
The only site-specific parameter in this pathway is total time of deposition (Tc). This should
be set to the expected lifetune of the combustion source (e.g., 30 years).
C-4-11
-------
DRAFT April 15, 1994
£
Table 4.2.1. Above-ground Vegetable Concentration Due to Direct Deposition
Exposure
Scenarios
All
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis (2-ethylhexyl) phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthaiate
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
pd _ 1000 -[(1.0 -Fv) -Dyd+(F\v
Parameter
Pd
1000
Dyd
Fw
Fv
Dyw
Rp
^0
Tp
Yp
Dyw)] Rp [(1. 0 - exp ( -kp Tp)]
Yp-kp
Definition
Concentration in plant due to direct deposition
(mg/kg)
Units conversion factor (mg/g)
Yearly dry deposition rate (g/m2/yr)
Fraction of wet deposition that adheres to plant
(dimensionless)
Fraction of air concentration in vapor phase .
(dimensionless)
Yearly wet deposition rate (g/m2/yr)
Interception fraction of edible portion of plant
(dimensionless)
Plant surface loss coefficient (yr'1)
Length of plant exposure to deposition of edible
portion of plant, per harvest (yrs)
Yield or standing crop biomass of the edible portion
of the plant (kg DW/m2)
Default Value
modeled (see Section 3)
chemical-specific (see
Section 5) .
chemical-specific (see
Section 5)
modeled (see Section 3)
0.3
.High end: 18
0.16
High end: 0.09
Description
This equation calculates the contaminant concentration in above-ground vegetation due to wet
and dry deposition of contaminant on the plant surface.
C-4-12
-------
DRAFT . April 15
Table 4.2,2. Above-ground Vegetable Concentration Due to Air-to-Plant Transfer
Exposure Scenarios
All
Chemicals
Benzo(a)pyrerie toxicity equivalents
Bis (2-ethylhexyl) phthalate
1,3-Dinitro benzene .
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs"
Pentachlorqnitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Pv
Concentration of pollutant in the plant due to air-to-plant
transfer (mg/kg)
Fv
Fraction of pollutant air concentration present in the vapor
phase (dimensionless)
chemical-specific
(see Section 5)
Concentration of pollutant in air due to direct emissions
modeled
(see Section 3)
Air-torplant biotransfer factor
([mg pollutant/kg plant tissue
pollutant/g air])
chemical-specific
(see Section 5).
Density of air (g/m3)
1.2 x 103
Description
This equation calculates the contaminant concentration in above-ground vegetation due to direct
uptake of vapor phase contaminants into the plant leaves. '
C-4-13.
-------
DRAFT April 15, 1994
4.3 Consumption of Root Vegetables
The equations hi this section calculate contaminant concentrations in root vegetables. Root
vegetables may be contaminated by combustion emissions through root uptake of contaminants
deposited on the soil. Direct deposition and vapor phase uptake are not important for root
vegetables, as none of the'edible portion is above the ground.
First, the soil concentration is calculated from the rate of deposition of contaminants onto
soils at the location of maximum combined (wet and dry) deposition (or an alternative location,
as discussed hi Section 3.4, Exposure Locations). Soil contamination by diffusion of vapors
from air has been omitted; instead, for the screening analysis vapors are treated hi the
COMPDEP model as particles for the purpose of estimating dry and wet deposition. The
calculation of soil concentration includes a loss term which can account for loss of contaminant
from the soil after deposition by several mechanisms, including leaching, erosion, runoff,
degradation, and volatilization. These loss mechanisms would all lower the soil concentration
associated with a specific deposition rate. For the screening analysis, the loss terms for
leaching, erosion, runoff, and volatilization have all been set to zero. This will result in a
conservative estimate of soil concentration. The degradation term is chemical-specific.
However, the degradation term is also set to zero for all contaminants except dioxin-like
compounds. Note that the elimination of the loss terms may be inappropriate for certain
chemicals for which the screening procedure is not intended (e.g., volatile organic compounds).
Uptake of contaminants from the soil pore water into the root of the plant is then calculated
from the soil concentration using the soil-water partition coefficient and a root concentration
factor (RCF).
The consumption of root vegetables pathway is used for all exposure scenarios.
The two high end parameters for consumption of root vegetables are mixing depth (Z) and
soil bulk density (BD). Both mixing .depth and soil bulk density should be. set to
10th percentile (or low) values.
The only site-specific parameter hi this pathway is total tune of deposition (Tc). This should
be set to the expected lifetime of the combustion source (e.g., 30 years).
C-4-14
-------
DRAFT
April 15, 1PP4
Table 4.3.1. Soil Concentration Due to Deposition
Exposure Scenarios
All
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis (2-ethylhexyl) phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene "
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
2,3,7,8-TCDDioxin only:
Sc =
Z -BD -ks
Tc)] -100
All other chemicals:
_Dyd+Dyw
Z -BD
Paramete
r
Definition
Default Value
Sc,
Soil concentration of pollutant after total time period of
deposition (mg/kg)_
Dyd
Yearly dry deposition rate of pollutant (g/m2/yr)
modeled (see Section 3)
Dyw
Yearly wet deposition rate of pollutant (g/m2/yr)
modeled (see Section 3)
ks
Soil loss constant (yr1)
calculated (see
Table 4; 1.2)
Total time period over which deposition occurs (yrs)
site-specific
100
Units conversion factor ([mg-m2]/[kg-cm2])
Soil mixing depth (cm)
High e ;d: 1
BD
Soil bulk density (g/cm3)
High end: 1.2
Description
These equations calculate soil concentration as a result of wet and dry deposition onto soil.
Contaminants are assumed to be incorporated only to a finite depth (the mixing depth, Z). The
first equation should be used when the soil loss term, ks,.is not zero; this equation is used only
for 2,3,7,8-TCDDioxin toxicity equivalents. The second equation should be used when ks is zero
(for all other chemicals).
C-4,15
-------
DRAFT. AprU 15, 1994
Table 4.3.2. Root Vegetable Concentration Due to Root Uptake
Exposure
Scenarios
All
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis (2-ethylhexyl) phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
total RGBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
Pr = Sc RCF
Parameter
Pr*
Sc
>
RCF
. *g
Kds
Definition
Concentration of pollutant in below ground plant parts due
to root uptake (mg/kg)
Soil concentration of pollutant (mg/kg)
Soil-water partition coefficient (mL/g)
Ratio of concentration in roots to concentration in soil
pore water ([mg pollutant/kg plant tissue FW]/[/^g
pollutant/mL pore water])
Default Value
calculated
(see
Table 4.3.1)
chemical-specific
(see Section 5)
chemical-specific
(see Section 5)
Description
This equation calculates the contaminant concentration in root vegetables due to uptake from the
soil water.
C-4-16
-------
DRAFT ' April 15
4.4 Consumption of Beef and Milk
The equations in this section calculate contaminant concentrations in beef tissue and milk due
to ingestion of contaminated forage and soil by beef and dairy cattle. Equations could be
provided or modified to reflect consumption of contaminated grain. However, ingestion of
grain is a less important pathway than ingestion of forage. The default values for ingestion of
above-ground plants are for forage consumption only.
Forage may be contaminated by combustion emissions through several mechanisms, including
direct deposition of contaminants onto the plant, direct uptake of vapor phase contaminants,
and root uptake of contaminants deposited on the soil. For the screening analysis, root uptake
is omitted. Root uptake is typically a much less important mechanism than direct deposition
to the aerial parts of plants. Direct uptake of vapor phase contaminant is included, as this can
be significant for some chemicals/ Direct deposition of particle .phase contaminants on the
plant is calculated at the location of maximum combined (wet and dry) deposition (or an
alternative location/as discussed in Section 3.4, Exposure Locations). Direct uptake of vapor
phase contaminants is calculated at the location of maximum air concentration (or an
alternative location, as discussed in Section 3.4, Exposure Locations).
Because direct uptake of vapor phase contaminants is a form of dry deposition,, to insure
conservation of mass the dry deposition rate calculated by the COMPDEP model (Dyd), which
for the screening analysis is used to represent dry deposition of emissions in both the particle
and vapor phases, is adjusted using a factor that represents the fraction of the chemical in the
particle phase. Similarly, the air concentration calculated by the COMPDEP model, -which
represents the total concentration .-of both airborne particles and vapors, is adjusted using a
factor that represents the fraction of the chemical in the vapor phase. The fraction in the vapor
phase (Fv) is chemical-specific. , The fraction in the particle phase (1 - Fv) is calculated from
the fraction in the vapor phase. :
It is also necessary to calculate the soil concentration resulting from deposition of
contaminants onto soils at the location of maximum combined (wet and dry) deposition (or an
alternative location, as discussed in Section 3.4, Exposure Locations). Soil contamination by
diffusion of vapors from air has been omitted; instead, for the screening analysis vapors are
treated in the COMPDEP model as particles for the purpose of estimating dry and wet
deposition The calculation of soil concentration includes a loss term which can account for
' loss of contaminant from the soil after deposition by several mechanisms, including leaching,
erosion, runoff, degradation, and volatilization. These loss mechanisms would all lower the
soil concentration associated with a specific deposition rate. For the screening analysis, the
loss terms for leaching, erosion, runoff, and volatilization have, all been set to zero. This will
result in a conservative estimate of soil concentration. The degradation term is
chemical-specific. However, the degradation term is also set to zero for all contaminants
except dioxin-like compounds. Note that the elimination of the loss terms may be
inappropriate for certain chemicals for which the screening procedure is not intended
(e.g., volatile organic compounds).
The consumption of beef and milk pathway is used only for the subsistence farmer exposure
scenario.
C-4-17
-------
April 15, 1994
The two high end parameters for the consumption of beef and milk are the soil mixing depth
(Z) and the crop yield (Yp). The soil mixing depth should be set to a 10th percentile (or low)
value. The crop yield (Yp) should also be set to a 10th percentile (or low) value.
The only site-specific parameter in this pathway is total time of deposition (Tc). This should
be set to the expected lifetime of the combustion source (e.g., 30 years).
C-4-18
-------
DRAFT
April 15, 1994
Table 4.4.1. Soil Concentration Due to Deposition
Exposure Scenarios
Subsistence Farmer
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
2,3,7,8-TCDDioxin only:
Sc =
Z -BD -ks
-[1.0 -eXp(-ks -To)] -100
All other chemicals:
_ Dyd
Z-BD
100
Parameter
Definition
Default Value
Sc
Soil concentration of pollutant after total time period of
deposition (mg/kg) ^ . .
Dyd
Yearly dry deposition rate of pollutant (g/m2/yr)
modeled
(see Section 3)
Dyw
Yearly wet deposition rate of pollutant (g/m2/yr)
modeled
(see Section 3)
ks
Soil loss constant (yr1)
calculated
(see Table 4.1.2)
Tc
Total-time period over which deposition occurs (yrs)
site-specific
100
Units conversion factor ([mg-m2]/[kg-cm2])
Soil mixing depth,(cm)
High end: 1
BD
Soil bulk density (g/cm3)
1.5
Description
These equations calculate soil concentration as a result of wet and dry deposition onto soil.
Contaminants are assumed to be incorporated only to a finite depth (the mixing depth, Z), The
first equation should be used when the soil loss term, ks/is not zero;, this equation is.used only
for 2,3,7,8-TCDDioxin toxicily equivalents. The second equation should be used when ks is zero
(for all other chemicals).
C-4-19
-------
DRAFT April 15, 1994
s ' - .
Table 4.4.2. Above-ground Plant Concentration Due to Direct Deposition
Exposure
Scenarios
Subsistence Farmer
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexachiorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
; Dfl _ 1000 [(! -Fv) -Dyd + (Fw
Dyw)J -Rp '[(1.0 -exp(-kp -Tp)]
Yp-kp
Parameter
Pd
1000
Dyd
Fw
Fv
Dyw
Rp
kp
Tp
Yp
Definition
Concentration in plant due to
direct deposition (mg/kg)
Units conversion factor (mg/g)
Yearly dry deposition rate (g/m2/yr)
Fraction of wet deposition that adheres to plant surfaces
(dimensionless)
Fraction of pollutant air concentration present in the vapor
phase (dimensionless)
Yearly wet deposition rate (g/m2/yr)
Interception fraction of the edible portion of the plant
tissue (dimensionless)
Plant surface los~ coefficient
(yr1)
Length of the plant's exposure to deposition per harvest
of the edible portion of the plant (yrs)
Yield or standing crop biomass of the edible portion of the
plant (kg DW/m2)
Default Value
modeled
(see Section 3)
chemical-specific
(see Section 5)
chemical-specific
(see Section 5)
modeled
(see Section 3)
0.44
18
0.12
High end: 0.02
Description
This
and
equation calculates the contaminant concentration in above-ground vegetation due to wet
dry deposition of contaminant on the plant surface. .
C-4-20
-------
DRAFT April 15, 1994
Table 4.4.3. Above-ground Plant Concentration Due to Air-to-Plant Transfer
Exposure Scenarios
Subsistence Farmer
Chemicals
Benzo(a)pyrene toxicity equivalents
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
, Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
Pv
(Fv -Cy) -Bv
Parameter
Definition
Default Value
Pv
Concentration of pollutant in the plant due to air-to-plant
transfer (mg/kg). .
Fv
Fraction of pollutant air concentration present in the vapor
phase (dimensionless)
chemical-specific
(see Section 5)
Cy
Concentration of pollutant In air due to direct emissions
pollutant/m3) .'/.,. -
modeled
(see Section 3)
Bv
Air-to-plant biotransfer factor
([mg pollutant/kg plant tissue DW]/[//g [pollutant/g air])
chemical-specific
(see Section 5)
Pa
Density of air (g/m3)
1.2 x 103
Description
This equation calculates the contaminant concentration in above-ground vegetation due to direct
uptake of vapor phase contaminants into the plant leaves.
C-4-21
-------
DRAFT April 15, 1994
Table 4.4.4. Beef Concentration Due to Plant and Soil Ingestion
Exposure Scenarios
Subsistence Farmer
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachiorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
A.f=(F-Qp -P+Qs -So) -Ba,
beef
Parameter
Definition
Default Value
Concentration of pollutant in beef (mg/kg)
Fraction of plant grown on contaminated soil and eaten by
the animal (dimensionless)
Qp
Quantity of plant eaten by the animal each day
(kg plant tissue DW/day)
8.8
Total concentration of pollutant in the plant eaten by the
'animal (mg/kg) = Pd + Pv
calculated
(see Tables
4.4.2, 4.4.3)
Qs
Quantity of soil eaten by the animal (kg soil/day)
0.4
Sc
Soil concentration (mg/kg)
calculated
(see
Table 4.4.1)
Ba,
'bo«f
Biotransfer factor for beef (d/kg)
chemical-specific
(see Section 5)
Description,
This equation calculates the concentration of contaminant in beef from ingestion of forage and
soil.
C-4-22
-------
DRAFT ' Aprill5,1994
Table 4.4.5. Milk Concentration Due to Plant and Soil Ingestion
Exposure Scenarios
Subsistence Farmer
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlprophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
-QP -P+Qs -So) -Bamit
milk
Parameter
Definition
Concentration of pollutant in milk (mg/kg)
Default Value
Fraction of plant grown on contaminated soil and eaten by
the animal (dimens'ionless) '.'''
Qp
Quantity of plant eaten by the anirria! each day
(kg plant tissue DW/day) _
11
Total concentration of pollutant in the plant eaten by the
animal (mg/kg) = Pd + Pv ;
calculated
(see Tables
4.4.2, 4-4.3)
Qs
Sc
Quantity of soil eaten by the animal (kg soil/day)
Soil concentration (mg/kg) ,
1.6
Ba
'milk .
Biotransfer factor for milk (day/kg)
calculated
(see
Table 4.4.1)
chemical-specific
(see Section 5)
Description
This equation calculates the concentration of contaminant in milk from ingestion of .forage,and
soil.
C-4-23
-------
DRAFT . . April 15, 1994
This Page Intentionally Left Blank
-------
DRAFT Aprill5,1994
\
4.5 Consumption of Fish
The equations in this section calculate contaminant concentrations in fish from contaminant
concentrations in the waterbody, either dissolved or total water column concentrations or
sediment concentrations. This is done in several steps.
The first step is to calculate the soil concentration resulting from deposition of contaminants
onto soils at the location of maximum combined (wet and dry) deposition (or an alternative
' location as discussed in Section 3.4, Exposure Locations). Soil contamination by diffusion of
vapors from air has been omitted; instead, for the screening analysis vapors are treated in the,
COMPDEP model as particles for the purpose of estimating dry and wet deposition. The
calculation of soil concentration includes a loss term which ,oan.account for loss of contaminant
from the soil after deposition by several mechanisms, including, leaching, erosion, runoff,
degradation, and volatilization. These loss mechanisms would all lower the soil concentration
associated with a specific deposition rate. For the screening analysis, the loss terms for
leaching, erosion, runoff, and volatilization have all been set to zero. This will result in a .
conservative estimate of soil concentration. The degradation term is chemical-specific.
However the degradation term is also set to zero for all contaminants except dioxm-like
compounds. Note that me elimination of the loss terms may be inappropriate .for certain
chemicals for which the screening procedure is not intended (e.g., volatile organic compounds).
The second step is to calculate the load of contaminant to the waterbody (Tables 4.5.2
through 4.5.8) at the location of maximum combined (wet and dry) deposition (or an alternative
location, as discussed in Section 3.4, Exposure Locations). Four pathways cause contaminant
loading of the waterbody: 1) direct deposition; 2) runoff from impervious surfaces within the
watershed: 3) runoff from pervious surfaces within the watershed; and 4) soil erosion from the
watershed! Other pathways have been omitted. Direct diffusion of vapor phase pollutants into
the waterbody is not a significant pathway for the chemicals included in the screening analysis.
Internal transformation may be considered as a waterbody loading pathway but this pathway
has also been omitted from the screening analysis. Instead, the effects of transformation
processes for constituents which are transformed (e.g., inorganic mercury to methyl mercury)
are implicit in the waterbody to fish tissue partitioning factor (e.g., the bioaccumulation factor
for mercury). For each chemical, only the most important pathways are used.
The third step is to calculate the total waterbody concentration (in the water column and
sediments) from the waterbody load (Table 4.5.9) and to partition the total concentration into
a dissolved water concentration, a total water column concentration, and a bed sediment
concentration (Tables 4.5.10 through 4.5.13). Only one of these three concentrations is
calculated for each chemical. Chemical dissipation from within the watubody, which may
occur by degradation, volatilization, or benthic burial, has been omitted from the screening
analysis This will result in a conservative estimate of the waterbody concentration. Note that
. the elimination of the dissipation terms may be inappropriate for certain chemicals for which
the screening procedure is not intended (e.g., volatile organic compounds).
The final step is to calculate the concentration in fish from. the total water column
concentration, the dissolved water concentration, or the bed sediment concentration using a
C-4-24
-------
-------
DRAFT April 15, 1994
B . " ' . .
bioconcentration factor, a bioaccumulation factor, or a sediment bioaccumulation factor, as
appropriate (Tables 4,5.14 through 4.5.16). . ; _
The fish ingestion pathway is used only for the subsistence fisher exposure scenario.
The two high end parameters for the fish consumption pathway are the soil mixing depth (Z)
and the waterbody total suspended solids concentration (TSS). The soil mixing depth should
be set to a 10th percentile (or low) value. The waterbody total suspended solids concentration
should be set to a 90th percentile (or high) value. .
There are a number of site-specific parameters hi the fish consumption pathway, including
total time of deposition (Tc)s and the various parameters characterizing the waterbody. The
total time of deposition should be set to the expected lifetime of the combustion source
.(e.g., 30 years). The following guidance is provided on the waterbody'parameters:
' ; - . ' "
Waterbody surface area (WA,V): this should be estimated from local maps.
Average volumetric flow (Vfx): average flows can be obtained from river and stream
gauging stations. If data from gauging stations are not available, the average flow can
be estimated based on the total upstream watershed area and the average runoff. The
total upstream watershed area (in length squared units) is multiplied by a unit area
surface water runoff (in length per time). The Water Atlas of the United States
(Geraghty, et al., 1973) provides maps with isolines of annual average surface water
runoff, which is defined as all flow'contributions to surface water bodies, including
direct runoff, shallow interflow^ and groundwater recharge. Flows may vary from 10s
nrVyr in small streams or ponds draining less .than a square kilometer to 109 rnVyr or:
more in large rivers.
\ - ' ' . .' "".-.'
Depth of the water column (dw): depths can be obtained from gauging stations or be
estimated based on other local data. Depths should represent the average depth of the
water column, so far as is possible..
Total watershed area (WAL): see Section 3.7 for guidance on estimating the watershed
area. This area should be the same as the effective drainage area.
Impervious watershed area (WAj): this is the portion of the total effective watershed
area that is impervious to rainfall (e.g., roofs, driveways, streets, parking lots, etc.) and
drains to the waterbody through a conveyance such as a gutter, storm sewer, ditch, or
canal. It can be estimated based on land use and other local information.
Annual average surface runoff (R): Surface runoff, R, can be estimated using the Water
Atlas of the United States (Geraghty et al., 1973). This reference provides maps with
isolines of annual average surface water runoff, which are defined as all flow
contributions to surface water bodies, including direct runoff, shallow interflow, and
ground water recharge. The range of values shown include 5 to 15 in/yr throughout the
Midwest corn belt, 15 to 30 in/yr hi the South and Northeast, 1 -to 5 in/yr in the desert
Southwest, and a wide range of 10 to 40 in/yr in the far West. Since these values are
' " .-' ' C-4-25 ' ' . " - .'
-------
DRAFT April 15, 1994
total contributions and not just surface runoff, they need to be reduced to estimate
surface runoff. A reduction of 50 percent, or one-half, should suffice if using the Water
Atlas for the R term. More detailed, site specific procedures for estimating the amount
of surface runoff, such as those based on the U.S. Soil Conservation Service curve
number equation (CNE), may also be used (see, for example, U.S. EPA, 1985). (Note
that all values must be converted to cm/yr.)
USLE rainfall factor (RF): The RF term represents the influence of precipitation on
erosion, and is derived from data on the frequency and intensity of storms. This value
is typically derived on a storm-by-storm basis, but average annual values have been
compiled (U.S. Department of Agriculture,""!982). Annual values range from < 50 for
the arid western United States to > 300 for the Southeast.
C-4-26
-------
DRAFT April 15,1994
Table 4.5.1. Watershed! Soil Concentration Due to Deposition
Exposure Scenarios
Subsistence Fisher
Chemicals
Arsenic ,
Beryllium
Benzo(a)pyrehe toxicity equivalents
Bis (2-ethylhexyi) phthalate
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate ,
. Nitrobenzene
total PCBs
2,3,7,8-TCDDioxin toxicity equivalents
Equation
2,3,7,8-TCDDioxin only:
Sc
All other chemicals:
.
+ DyWW -[l-exp (-ks Tc)] 100
Z -BD -ks
.
+-D3W ..TV. -inn
Z -BD
Parameter
.Definition
Default Value
Sc
Average watershed soil concentration after time period of
deposition (mg/kg) _ '__
Dydw
Yearly average dry depositional flux of pollutant onto the
watershed (g/m2/yr)
modeled
(see Section 3)
Dyww
Yearly average wet depositional flux of pollutant onto the
watershed (g/m2/yr)
modeled
(see Section 3)
ks
Total chemical loss rate constant from soil (yr1)
calculated
(see
Table 4.1.2)
Representative watershed mixing depth .to which
deposited pollutant is incorporated (cm)
High end: 1
BD
Representative watershed soil bulk density (g/cm3)
. 1.5
Tc
Total time period over which deposition has occurred (yr)
site-specific
100
Units conversion factor (mg-m2/kg-cm2)
Description
These equations .calculate watershed soil concentration as a result of wet and dry deposition.
Contaminants are assumed to be incorporated only to a finite depth (the mixing depth, Z). The
first equation should be used when the soil loss term, ks, is not zero'; this equation is used only
for 2,3,7,8-TCDDioxin .toxicity equivalents. The second equation should be used when ks is zero
(for all other chemicals). . . ' : -.'''.'
C-4-27
-------
DRAFT
April 15, 1994
Table 4.5.2. Total Waterbody Load
Exposure
Scenarios
Subsistence Fisher
Chemicals -
'Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis (2-ethylhexyI) phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
2,3,7,8-TCDDioxin toxicity equivalents
Equation
LT =LDep + LRIt+LR+LE
Parameter
LT
LD.P
LR,
LR
LE
Definition
Total contaminant load to the
water body (g/yr)
Deposition of particle bound contaminant to the water
body (g/yr) . . .'
-*
Runoff load from impervious surfaces (g/yr)
Runoff load from pervious surfaces (g/yr)
Soil erosion load (g/yr)
Default Value
calculated
(see
Table 4.5.3)
calculated
(see
Table 4.5.4)
calculated
(see
Table 4.5.5)
calculated
(see
Table 4.5.6)
Description
This equation calculates the total average waterbody load from the deposition, runoff, and erosion
loads. Not ah types of loads (deposition, runoff, or erosion) are used for each chemical.
C-4-28
-------
DRAFT
April 15, 1994
Table 4.5.3. Deposition to Waterbody
Exposure
Scenarios
Subsistence Fisher .
Chemicals
1,3-Dinitro benzene
Hexachlorobenzene
Mercury
Pentachloronitrobenzene
Equation
LDtp = (Dyds
l-Deo '
Dyds
Dyws
WA,
f- Dyws) WAV
Definition
Direct deposition load (g/yr)
Representative yearly dry deposition rate of pollutant onto
surface water body (g pollutant/m2/yr)
Representative yearly wet deposition rate of pollutant onto
surface water body (g pollutant/m2/yr)
Water body area (m2)
Default Value
modeled
. (see Section 3)
modeled
(see Section 3)
site-specific
Description
This equation calculates the average load to the waterbody from direct deposit on onto the
surface of the waterbody.
C-4-29
-------
DRAFT
AprU 15, 1994
Table 4.5.4. Impervious Runoff Load to Waterbody
Exposure Scenarios
Subsistence Fisher
Chemicals
Arsenic
Beryllium
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexachlorotaenzene
Mercury
Nitrobenzene
Pentachloronitrobenzene
Equation
Lm = (Dyww + Dydw) WA,
Parameter
Definition
Default Value
-Rl
Impervious surface runoff load (g/yr)
WA,
Impervious watershed area receiving pollutant deposition
(m2)
site-specific-
Dyww
Yearly wet deposition flux onto the watershed (g/m2/yr)
modeled
(see Section 3)
Dydw
Yearly dry deposition flux onto the watershed (g/m2/yr)
modeled
(see Section 3)
Description
This equation calculates the average .runoff load to the waterbody from impervious surfaces in the
watershed from which runoff is conveyed directly to the waterbody.
C-4-30
-------
DRAFT
April 15, 1994
Table 4.5.5. Pervious Runoff Load to Waterbody
2,6-Dinitrd toluene
Nitrobenzene
Exposure Scenarios
Arsenic
Beryllium
2,4-Dinitro toluene
Parameter
LR = R ' (WAL , -
Pervious surface runoff load (g/yr)
Average annual surface runoff (cm/yr)
site-specific
Sc
Pollutant concentration in watershed soils {mg/kg)
calculated
(see.
Table 4.5.1)
BD
Soil bulk density (g/cm3)
1.5
Kds
Soil-water partition coefficient (L/kg)
chemical-specific
(see Section 5)
WA,
Total watershed area receiving pollutant deposition (m )
'- site-specific
WA,
Impervious watershed area receiving pollutant deposition
(m2) ' .--'.
site-specific
0.01
Units conversion factor (kg-cnr^/mg-m2)
Volumetric soil water content (cm3/cm3)
=====
Description
0.2
This equation calculates the average runoff load to the waterbody from peivious soil surfaces in
the watershed.
C-4-31
-------
DRAFT
April 15, 1994
Table 4.5.6. Erosion Load to Waterbody
Exposure Scenarios
Subsistence Fisher
Chemicals
Benzo(a)pyrene toxicity equivalents total PCBs
Bis (2-ethylhexyl) phthalate 2,3,7,8-TCDDioxin toxicity equivalents
Di(n)octyl phthalate
Equation
LE
Parameter
LE
x.
Sc
BD
0,
Kd.
WAL
WA,
SD
ER
0.001
Sc -Kd -BD
= x (WA - WA ) - SD FR ' - 0
e \ " es + Kds -BD
r"
Definition
Soil erosion load (g/yr)
Unit soil loss (kg/m2/yr)
Pollutant concentration in watershed soils (mg/kg)
Soil bulk density (g/cm3)
Volumetric soil water content (cm3/cm3)
Soil-water partition coefficient (L/kg)
Total watershed area receiving pollutant deposition (m2)
Impervious watershed area receiving pollutant deposition
(m2)
Watershed sediment delivery ratio (unitless)
Soil enrichment ratio (unitless)
Units conversion factor ([g/kg]/[mg/kg])
001
Default Value
calculated
(see
Table 4.5.7)
calculated
(see
Table 4.5.1)
1-5
0.2 .
chemical-specific
(see Section 5)
site-specific
site-specific
calculated
(see
Table 4.5.8)
3
Description
This equation calculates the load to the waterbody from soil erosion.
C-4-32
-------
DRAFT
AprU 15, 1994
Table 4.5.7. Universal Soil Loss Equation (USLE)
Exposure Scenarios
Subsistence Fisher
Chemicals
Benzo(a)pyrene toxicity equivalents
Bis (2-ethylhexyl) phthalate
Di(n)octyl phthalate
total PCBs
2,3,7,8-TCDDioxin toxicity equivalents
Equation
X =RF -K -LS -C -P
907.18
0004047
Parameter
Definition
Default Value
Unit soil loss (kg/m2/yr)
RF
USLE rainfall (or erasivity) factor (yr1)
site-specific
K
USLE erodibility-factor (ton'/acre)
0.36
LS
USLE length-slope factor (unitless)
1.5
C
USLE cover management factor (unitless)
0.1
USLE supporting practice factor (unitless)
907.18
Conversion factor (kg/ton)
0.004047
Conversion factor (km2/acre)
Description
This equation calculates the soil loss rate from the watershed, using the Universal Soil Loss
Equation; the result is used in the soil erosion load equation. -
T-4-33
-------
DRAFT
April 15, 1994
Table 4.5.8. Sediment Delivery Ratio
Exposure Scenarios
Subsistence Fisher
Chemicals
Benzo(a)pyrene toxicity equivalents
Bis (2-ethylhexyl) phthalate
Di(n)octyl phthalate
total PCBs
,2,3,7,8-TCDDioxin toxicity equivalents
Equation
SD = a
Parameter
Definition
Default Value
SD
Watershed sediment delivery ratio (unitless) '
WAL
Watershed area receiving fallout (m2)
site-specific.
Empirical slope coefficient
-0.125
Empirical intercept coefficient
depends on
watershed area;
see table below
Description
This equation calculates the sediment delivery ratio for the watershed; the result is used in the
soil erosion load equation.
Values for Empirical Intercept Coefficient, a
Watershed
area
(sq. miles)
^ 0.1
1
10
100
1,000
it it
G
coefficient
. (unitless)
2-1
1.9
1.4
1.2
- 0.6
1 sq. mile = 2.59x1 06 m2
C-4-34
-------
DRAFT
April 15, 1994
Table 4.5.9. Total Waterbody Concentration
E-xposure Scenarios
Subsistence Fisher
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis (2-ethylhexyl) phthalate'
1,3-Dinitro. benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)pctyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
2,3,,7,8-TCDDioxin toxicity equivalents
Equation
Vf -f
Jx JVM.
Parameter
Definition
Default Value
Total water body concentration, including water column
and bed sediment (mg/L) .,
LT
Total chemical load into water body, including deposition,
runoff, and erosion (g/yr)
calculated .
(see
Table 4.5.2)
Vf,
Average volumetric flow rate through water body (m3/yr)
site-specific
Fraction of total water body contaminant concentration
that occurs in the water column (unitless)
Description
calculated
(see
Table 4.5.10)
This equation calculates the total waterbody concentration, including both the water-column and
the bed sediment. '
C-4-35
-------
DRAFT April 15, 1994
Table 4.5.10. Fraction in Water Column and Bed Sediment
Exposure Scenarios
Subsistence Fisher
Chemicals
Arsenic Di(n)octyl phthalate
Beryllium Hexachlorobenzene
Benzo(a)pyrene toxicity equivalents Mercury
Bis (2-ethylhexyl) phthalate _ ' Nitrobenzene
1,3-Dinitro benzene . total PCBs
2,4-Dinitro toluene . Pentachloronitrobenzene
2,6-Dinitro toluene 2,3, 7,8-TCDDioxin toxicity equivalents
Equation
J w
Parameter
'witor
Kd-
TSS
10*
dw
db
6M
Kdb,
BS
With
(1 + Kdsw 'TSS - 10~6)
^er /i , v^J T^OO i /i -6 \ *3 . /a
(1 + Kdsw 'TSS 10^) 'dw + (6bs
f = 1 -f
J berth J voter
4,
+ Kdbs -BS) -db
Definition
Fraction of total water body contaminant concentration
that occurs in the water column (unitless)
Suspended sediment/surface water partition
(L/kg)
coefficient
Total suspended solids (mg/L)
Conversion factor (kg/mg)
Depth of the water column (m)
Depth of the upper benthic layer (m)
Bed sediment porosity (L^aJL)
Bed sediment/sediment pore water partition
(L/kg)
coefficient
Bed sediment concentration (g/cm3)
Fraction of total water body contaminant concentration
that occurs in the bed sediment (unitless)
Default Value
chemical-specific
(see Section 5)
High end: 80
site-specific
0.03
0.5
chemical-specific
(see Section 5)
1.0
Description
These equations calculate the fraction of total waterbody concentration occurring in the water
column and the bed sediments.
C-4-36
-------
DRAFT
April 15, 1994
Table 4.5.11. Total Water Column Concentration
Exposure
Scenarios
.Subsistence Fisher
Chemicals
Benzo(a)pyrene toxicity equivalents
Bis (2-ethylhexyI) phthalate
Di(n)octyl phthalate
Hexachlorobenzerie
Mercury
. Equation
wt J water
Parameter
Cw,
'water
Cwtot
db
dw . . . ;
, :*.+*>
~' . *;
Definition
Total concentration in water column (mg/L)
Fraction of total water body contaminant . concentration
that occurs in the water column (unitless)
Total water concentration in surface water system,
including water column and bed sediment (mg/L)
Depth of upper benthic layer
(m)
Depth of the water column (m) , _
Default Value
calculated
(see
Table 4.5.10)
calculated
(see
Table 4.5.9)
0.03
site-specific
Description
This equation calculates the total water column concentration of contaminant; this includes both
dissolved contaminant and contaminant sorbed to suspended solids.
C-4-37
-------
DRAFT
April 15, 1994
Table 4.5.12. Dissolved Water Concentration
Exposure Scenarios
Subsistence Fisher
Chemicals
Arsenic
Beryllium
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Nitrobenzene
Pentachloronitrobenzene
Equation
c*
Parameter
C^ Dissolved phase
c*
' 1 + Kdm -TSS -10-*
Definition
water concentration (mg/L)
0^ Total concentration in water column (mg/L)
Kdw Suspended sediment/surface water partition coefficient
(L/kg)
TSS Total suspended
solids (mg/L)
Default Value
calculated
(see
Table 4.5.11)
chemical-specific
(see Section 5)
High end: 80
Description
This equation calculates the concentration of contaminant dissolved in the water column.
C-4-38
-------
DRAFT
April 15, 1994
Table 4.5.13. Concentration Sorbed to Bed Sediment
Exposure Scenarios
Subsistence Fisher
Chemicals
total PCBs
2,3,7,8-TCDDioxin toxicity equivalents
Equation
= f -r
sb Jt,,n,h *. Q +
Concentration sorbed to bed sediments (mg/kg)
Default Value
'benth
Fraction of total water body contaminant concentration
that occurs in the bed sediment (unitless)
calculated
(see
Table 4.5.10)
'wtot
Total water concentration in surface water system,
including water cblumn and bed sediment (mg/L)
calculated ,
(see
Table 4.5.9)
Total depth of water column (m)
site-specific
Depth of the upper benthic layer (m)
0.03
Bed sediment porosity (unitless)
sediment concentration
0.5
Bed sediment/sediment pore water partition coefficient
(L/kg) .. .
chemical-specific
(see Section 5)
1.0
equation calculates the concentration of contaminant sorbed to bed sediments.
C-4-39
-------
DRAFT April 15, 1994
Table 4.5.14. Fish Concentration from Dissolved Water Concentration
Exposure
Scenarios
Subsistence Fisher
Chemicals
Arsenic
Beryllium
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Nitrobenzene
Pentachloronitrobenzene '
Equation
Cfsh =Cc
*, "BCF
Parameter Definition Default Value
Cfitn Fish concentration (mg/kg) -
C^ Dissolved water concentration (mg/L) calculated
(see
Table 4.5.12)
BCF Bioconcentration factor (L/kg)
chemical-specific
(see Section 5)
Description
This equation calculates fish concentration from dissolved water concentration, using a
bioconcentration factor.
C-4-40
-------
DRAFT April 15, 1994
Table 4.5.15. Fish Concentration from Total Water Column Concentration
Exposure Scenarios
Subsistence Fisher
Chemicals
Benzo(a)pyrene toxicity equivalents
Bis (2-ethylhexyl) phthalate
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Equation
-BAF
Parameter
Definition
Default Value
Fish concentration (mg/kg)
Total water column concentration (mg/L)
calculated
(see
Table 4.5.11)
BAF
Bioaccumulation factor (L/kg)
chemical-specific
(see Section 5)
Description
This equation calculates fish concentration from total water column concentration, using a
bioaccumulation factor. , '
C-4-41
-------
DRAFT
April 15, 1994
Table 4.5.16. Fish Concentration from Bed Sediments
Exposure
Scenarios
Subsistence Fisher"
Chemicals
total PCBs
2,3,7,8-TCDDioxin toxicity equivalents '
Equation
'C. '/.... -BSAF
s^ so J lipid
Parameter
CriJh
csb
f|,Bid
BSAF
ocied
Jish
«
-------
DRAFT April 15, 1994
A ' ; ' -
5. CHEMICAL-SPECIFIC PARAMETERS
5.1 Toxicity Equivalency Factors for Dioxin-Like Compounds and Polycyclic Aromatic
Hydrocarbons
For the screening analysis, the emissions of all 2,3,7,8 substituted dibenzo(p)dioxins and
dibenzofurans are converted to 2,377,8-tetrachlorodibenzo(p)dioxin. toxicity equivalents
(2,3J,8-TCDD-TEQ)follpwmgEPA''S//zfenmPro^
Mixtures of Chlorinated Dibenzo-p-Dioxins and Dibenzofurans (CDDs andCDFs) (U.S. EPA,
1989). Table 5.1.1 presents the toxicity equivalency factor (TEF) for each congener and the
calculations necessary for estimating the 2,3,7,8-TCDD-TEQ emissions. The
2,3,7,8-TCDD-TEQ chemical group is modeled using the fate and transport properties of the
2,3,7,8-TCDD congener. ,
Similarly, the emissions of seven polycyclic aromatic hydrocarbons (PAH's) are converted to
benzo(a)pyrene toxicity equivalents (BaP-TEQ) following EPA's Provisional Guidance for the
Quantitative Risk Assessment of Polycyclic Aromatic Hydrocarbons (OHEA, 1993). Table 5.1.2
presents the toxicity equivalency factor (TEF) for each PAH and the calculations necessary for
1 estimating the BaP-TEQ emissions. The BaP-TEQ chemical group is modeled using the fate and
transport properties of benzo(a)pyrene.
C-5-1
-------
DRAFT
April 15, 1994
Table 5.1.1. Toxicity Equivalence Factors (TEF's) for
Dioxin and Furan Emissions
Congener
2,3,7,8-Tetrachlorodibenzo(p)dioxin
1,2,3,7,8-Pentachlorodibenzo(p)dioxin
1,2,3,4,7,8-Hexachlorodibenzo(p)dioxin
1,2,3,6,7,8-Hexachlorodibenzo(p)dioxin
1,2,3,7,8,9-Hexachlorodibenzo(p)dioxin
1,2,3,6,7,8,9-Heptachlorpdibenzo(p)dioxin
Octachlorodibenzo(p)dioxin
2,3,7,8-Tetrachlorodibenzofuran
1 ,2,3.7.8-Pentachlorodibenzofuran
2,3,4,7,8-Pentachlorodibenzofuran
1,2,3,4,7,8-Hexachlorodibenzofuran
1,2,3,6,7,8-Hexachlorodibenzofuran
1,2,3,7,8,9-HexachIorodibenzofuran
2,3,4,6.7,8-HexachIorodibenzofuran
1,2,3,4,6,7,8-Heptachlorodibenzofuran
1,2,3,4,7,8,9-HeptachIorodibenzofuran
Octachlorodibenzofuran
Emission Rate x
(9/s)
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
facility-specific x
Total 2,3,7,8-TCDD-TEQ Emission Rate
1 (EPA, 1989)
TEF1
1 =
0.5
0.1
0.1
0.1
0.01 =
0.001
0.1
0.05 =
0.5
0.1
0.1
0.1
0.1
0.01
0.01 =
0.001 =
= £ =
2,3,7,8-TCDD
TEQ
Emission
Rate (g/s)
C-5-2
-------
DRAFT
April 15, 1994
Table 5.1.2. Toxtcity Equivalence Factors (TEF's) for
PAH Emissions
PAH
Benzo(a)pyrene (BaP)
Benz(a)anthracene .
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Chrysene ,'
Dibenz(a,h)anthracene
lndeno(1,2,3-cd)pyrene
Emission Rate
(9/s)
facility-specific
facility-specific
facility-specific
facility-specific
facility-specific
facility-specific
facility-specific
Total BaP-TEQ Emission
1 (OHEA, 1993)
X
X
X
X
X
X
X
X
Rate
TEF1
1.0
0.1 =
0.1 =
0.01
0.001 =
1.0
0.1 =
E =
. BaPTEQ
Emission Rate
. (g/s)
., *
",
C-5-3
-------
DRAFT
5.2 Other Chemical Parameters
April 15, 1994
This section gives the values for the chemical-specific parameters for the pathway equations
hi Section 4, along with the health related criteria or benchmarks for characterizing risk that are
used hi Section 6. The data are
organized by chemical in ^^^^^^^li
alphabetical order. There are
15 tables, one for each chemical
or group of chemicals, as
indicated in the text box. The
data in the tables include
physical/chemical properties data,
biological transfer factors, and
health .criteria or benchmarks.
For each parameter, the tables
indicate the equations in Section 4
or Section 6 for which the
parameter is used. A value of NA
indicates that the value is not
applicable for that chemical.
Although a value for the
parameter may exist for the
chemical, it is not included here
because it is not needed for the
screening analysis. (No table is
provided for lead; only a soil
concentration is calculated for
lead, a calculation which requires
no chemical-specific inputs.)
Chemical
Table
Arsenic
Beryllium
Benzo(a)pyrene Toxicity Equivalents
Bis(2-ethylhexyl) phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octy) phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin Toxicity
Equivalents
5.2.1.
5.2.2.
5.2.3.
5.2.4.
5.2.5.
5.2.6.
5.2.7.
5.2.8.
5.2.9.
5.2.10.
5.2.11
5.2.12.
5.2.13.
5.2.14.
5.2.15.
C-5-4
-------
DRAFT
April 15, 1994
Table 5.2.1. Chemical-Specific Inputs for
Arsenic
Parameter |
^=^=^=^==
Chemical/Phy
ksg
Fv
Kd,
Kdw
Kdbs
Definition
sical Properties
Soil loss constant due to degradation (yr1)
Fraction of pollutant air concentration present in the
vapor phase (dimensionless)
Soil-water partition coefficient (mL/g or L/kg)
Suspended sediment-surface water partition coefficient
(L/kg)
Bottom sediment-sediment pore water partition
coefficient (L/kg)
Equation
4.1.2
4.2.2,
4.4.3
4.3.2,
4.5.5,
4.5.6
4.5.10,
4.5.12
4.5.10,
4.5.13
Value
I
NA ,' I
0
29
220
120
Transfer Factors
Bv
Air-to-plant biotransfer factor (f//g pollutant/g plant
tissue DW]/[j/g pollutant/g air]) i
4.2.2,
'4.4.3
NA
RCF
Ratio of concentration in the roots to concentration in
soil pore water (f//g pollutant/g plant tissue FW]/f//g
pollutant/mL pore water])
4.3.2
0.008
Biotransfer factor for beef (day/kg)
4.4.4
0.002
Biotransfer factor for milk (day/kg)
4.5.5
0.006
Fish bioconcentration factor (L/kg)
4.5.14
44
Fish bioaccumulation factor (L/kg)
4.5.15
NA
Fish biota to sediment accumulation factor (unitless)
4.5.16
NA
Other Parameters
Fraction of wet deposition that adheres to plant surfaces
(dimensionless)
4.2.1,
4.4.2
0.1
Health Benchmarks
Cancer Slope Factor (per mg/kg/day)
6.1.6,
6.2.6,
6.3.5,
6.4.5
Reference Dose (mg/kg/day)
C-5-5
-------
DRAFT
April 15, 1994
Table 5.2.2. Chemical-Specific Inputs for
Beryllium
Parameter
Definition
Equation
Value
Chemical/Physical Properties
ksg
Fv
Kd,
Kdaw
Kd,,
Soil loss constant due to degradation (yr1)
Fraction of pollutant air concentration present in the
vapor phase (dimensionlessj -
Soil-water partition coefficient (mL/g or L/kg)
Suspended sediment-surface water partition coefficient
(L/kg)
Bottom sediment-sediment pore water partition
coefficient (L/kg)
4.1.2
4.2.2,
4.4.3
4.3.2,
4.5.5,
4.5.6
4.5.10,
4.5.12
4.5.10,
4.5.13
NA
0
70
525
280
Transfer Factors ~ V-;'"/:\. '.;'..-:.'.'.'.:..:,'.::';.', .^ -..,./..'''':'/. :.:: .
Bv
RCF
Ba^,
Bamilk
BCF
BAF
BSAF
Air-to-plant biotransfer factor (fo/g pollutant/g plant tissue
DVVJ/tA/g pollutant/g air])
Ratio of concentration in the roots to concentration in
soil pore water (fag pollutant/g plant tissue FW]/[/t/g
pollutant/mL pore water])
Biotransfer factor for beef (day/kg)
Biotransfer factor for milk (day/kg)
Fish bioconcentration factor (L/kg)
Fish bioaccumulation factor (L/kg)
Fish biota to sediment accumulation factor (unitless)
4.2.2,
4:4.3
4.3.2
4.4.4
4.5.5
4.5.14
4.5.15
4.5.16
NA
0.0015
0.001
9E-7
20
NA
,NA
Other Parameters ' ',,* ^.{\/i--. ..:- '':''::":,;.: .*.''..' .-'.:'''','. '..' . .''..''"'-
Fw
Fraction of wet deposition that adheres to plant surfaces
(dimensionless)
4.2.1,
4.4.2
0.1
Health Benchmarks "".'' ; , '
CSF
RfD
Cancer Slope Factor (per mg/kg/day)
Reference Dose (mg/kg/day)
6.1.5,
6.2.5,
6.3.4, '
6.4.4
6.1.6,
6.2.6,
6.3,5,
6.4.5
4.3E+0
5E-3
C-5-6
-------
DRAFT
AprU 15, 1994
Table 5.2.3. Chemical-Specific Inputs for
Benzo(a)pyrene Toxicity Equivalents
Parameter
Definition
Chemical/Phys cat Properties
ksg
Fv
Kds
Kd5W
Kdbs
Soil loss constant due to degradation (yr1)
Fraction of pollutant air concentration present in the
vapor phase. (dimensionless) v -
Soil-water partition coefficient (mL/g or L/kg)
Suspended sediment-surface water partition coefficient
(L/kg)
Bottom sediment-sediment pore water partition
coefficient (L/kg)
Equation
,4.1.2
4.2.2,
4.4.3
4.3.2,
4.5.5,
4.5.6
4.5.10,
. 4.5.12
4.5.10,
4.5.13 .
Value I
NA
,0.4
12,000
90,000
48,000
Bv
RCF
Babeef
Bamilk
BCF
BAF
BSAF
Air-to-plant biotransfer factor (|//g pollutant/g plant
tissue DW]/[A/g pollutant/g air])
Ratio of concentration in the roots to concentration in
soil pore water (frig pollutant/g plant tissue FW]/[//g
pollutant/mL pore water])
Biotransfer factor for beef (day/kg)
Biotransfer factor for milk (day/kg)
Fish bioconcentration factor (L/kg)
Fish bioaccumulation factor (L/kg)
Fish biota to sediment accumulation factor (unitless)
4.2.2,
4.4.3
4.3.2
4.4.4
4.5.5
4.5.14
4.5.15
4.5.16
1,300,000
1,600 .
0.034
0.011
NA
1,000,000
NA
Other Parameters
Fw
Fraction of wet deposition that adheres to plant
surfaces (dimensionless)
4.2.1,
4.4.2
1
.-:....' . ' -.-- - ' . .Jl
Health Benchmarks II
CSF
RfD
Cancer Slope Factor (per mg/kg/day)
Reference Dose (mg/kg/day)
6.1.5,
6.2.5,
6.3.4,
6.4.4
6.1.6,
6.2.6,
6.3.5,
6.4.5
. 7.3
NA
C-5-7
-------
DRAFT
April 15, 1994
Table 5.2.4. Chemical-Specific Inputs for
Bis (2-ethyihexyl) phthalate
Parameter
Definition
Equation
Value
Chemical/Physical Properties
ksg
Fv
Kd,
Kdsw
Kdb,
Soil loss constant due to degradation (yr~1)
Fraction of pollutant air concentration present in the
vapor phase (dimensionless)
Soil-water partition coefficient (mL/g or L/kg)
Suspended sediment-surface water partition coefficient
(L/kg)
Bottom sediment-sediment pore water partition
coefficient (L/kg) *
4.1.2
4.2.2,
4.4.3 .
4.3.2,
4.5.5,
4.5.6
4.5.10,
4.5.12
4.5.10,
4.5.13
NA
0.8
46,000
350,000
180,000
Transfer Factors .
Bv
RCF
Ba,^,
Bamitk
BCF
BAF
BSAF
Air-to-plant biotransfer factor (|//g pollutant/g plant
tissue DW]/[pg pollutant/g air])
Ratio of concentration in the roots to concentration in
soil pore water ([//g pollutant/g plant tissue FW]/(//g
pollutant/mL pore water])
Biotransfer factor for beef (day/kg)
Biotransfer factor for milk (day/kg)
Fish bioconcentration factor (L/kg)
Fish bioaccumulation factor (L/kg)
Fish biota to sediment accumulation factor (unitless)
4.2.2,
4.4.3
4.3.2
4.4.4
4.5.5
4.5.14
4.5.15
.4.5.16
640,000
4,500
NA
NA ,
NA
66,000
NA
Other Parameters , ..,-.'.. :..-./ ;: .; ;jv' ';.-: > .':;,,.. .-.-,. ..-;.. ;-'..'.. -: -.:;.. .. ' .
Fw
Fraction of wet deposition that adheres to plant surfaces
(dimensionless)
4.2.1,
4.4.2
1
Health Benchmarks . , ';'.'.; ,.":': ':._ .'"
CSF
RfD
Cancer Slope Factor (per mg/kg/day)
Reference Dose (mg/kg/day)
6.1.5,
6.2.5, .
6.3.4,
6.4.4
6.1.6,
6.2.6,
6.3.5,
6.4.5
1.4E-2
2E-2
C-5-8
-------
DRAFT
AprU 15, 1994
Table 5.2.5. Chemical-Specific Inputs for
1,3-Dinitro benzene
Parameter |
Definition
Equation |
Value I
| Chemical/Physical Properties .
ksg
Fv
Kds
J Kdsw
Kdbs
Soil loss constant due to degradation (yr1)
Fraction of pollutant air concentration present in the
vapor phase (dimensionless)
Soil-water partition coefficient (mL/g or L/kg)
Suspended sediment-surface water partition
coefficient (L/kg)
Bottom sediment-sediment pore water partition
coefficient (L/kg)
4.1.2
4.2.2,
4.4.3
4.3.2,
4.5.5,
4.5.6
4.5.10,
4.5.12
4.5.10,
4.5.13
, NA
1
0.28
2
- 1-1
| Transfer Factors ' , , :
I Bv
I BCF
I Babeef
I Bamilk
I BCF
I BAF
I BSAF
Air-to-piant biotransfer factor (fr/g pollutant/g plant
tissue DW]/[//g pollutant/g air])
Ratio of concentration in the roots to concentration in
soil pore water (f//g pollutant/g plant tissue FW]/[//g
pollutant/mL pore water]) .' - .
Biotransfer factor for beef (day/kg) ,
Biotransfer factor for milk (day/kg)
Fish bioconcentration factor (L/kg)
Fish bioaccumulation factor (L/kg)
Fish biota to sediment accumulation factor (unitless)
4.2.2,
4.4.3
4..S.2
1 4.4.4
4.5.5
4.5.14
4.5.15
4.5.16
0.0068
1.25
7.9E-7
2.5E-7
1.4
NA
NA
I Other Parameters , . . ." . .':.'". :.;.' ;' -^ : -./ ' : . ', t ;: ;. ';. ' ; ;? : '? "':'" ::": : :;.'.'-.::-;.N.';.;;'.:; ;'.\ -"" ; -
I Fw
Fraction of wet deposition that adheres to plant .
surfaces (dimensionless) ' ,
4.2.1,
4.4.2
.0.1
I Health Benchmarks v ; ''''''.
I CSF
I RfD
Cancer Slope Factor (per mg/kg/day)
Reference Dose (mg/kg/day) ,
6.1.5,
6.2.5,
6.3.4,
6.4.4
6.1.6,
6:2.6,
6.3.5,
6.4.5
i=====
NA
1E-4
C-5-9
-------
DRAFT
April 15, 1994
Table 5.2.6. Chemical-Specific Inputs
2,4-Dinitro toluene
for
Parameter
Definition
Equation
Value
Chemical/Physical Properties
ksg
Fv
Kd,
Kdw
Kdb,
Soil loss constant due to degradation (yr1)
Fraction of pollutant air concentration present in the
vapor phase (dimensionless)
Soil-water partition coefficient (mL/g or L/kg)
Suspended sediment-surface water partition coefficient
(L/kg)
Bottom sediment-sediment pore water partition
coefficient (L/kg)
4.1.2
4.2.2,
4.4.3
4.3.2,
4.5.5,
4.5.6
4.5.10,
4.5.12
4.5.10,
4.5.13
NA
1
0.87
6.5
3.5
Transfer Factors
Bv
RCF
Ba^,
Bamilk
BCF
BAF
BSAF
Air-to-plant biotransfer factor (\fig pollutant/g plant
tissue DW]/[//g pollutant/g air])
Ratio .of concentration in the roots to concentration in
soil pore water (fjt/g pollutant/g plant tissue FW]/[//g
pollutant/mL pore water])
Biotransfer factor for beef (day/kg)
Biotransfer factor for milk (day/kg)
Fish bioconcentration factor (L/kg)
Fish bioaccumulation factor (L/kg)
Fish biota to sediment accumulation factor (unitless)
4.2.2,
4.4.3
4.3.2
4.4.4
4.5.5
4.5.14
4.5.15
4.5.16 ,
150
1.9
2.5E-6
7.9E-7
3.2
NA
NA
Other Parameters , :..;,,;/.,. . : ,
Fw
Fraction of wet deposition that adheres to plant
surfaces (dimensionless)
4.2.1,
4.4.2
0.1
Health Benchmarks V ...: .' '.-..-. .
CSF
RfD
Cancer Slope Factor (per mg/kg/day)
Reference Dose (mg/kg/day)
6.1.5,
6.2.5,
6.3.4,
6.4.4
6.1.6,
6.2.6,
6.3.5,
6.4.5
6.8E-1
2E-3
C-5-10
-------
DRAFT
April 15, 1994
Table 5.2.7. Chemical-Specific Inputs for
2,6-Dinitro toluene
Parameter
Definition
Equation
Value
Chemical/Physical Properties
ksg
Fv
Kd,
Kdsw
Kdbs
Soil loss constant due to degradation (yr1)
Fraction of pollutant air concentration present in the
vapor phase (dimensionless)
Soil-water partition coefficient (mL/g or L/kg)
Suspended sediment-surface water partition coefficient
(L/kg)
Bottom sediment-sediment pore water partition
coefficient (L/kg)
4.1.2
4.2.2,
4.4.3
4.3.2,
4.5.5, '
. 4.5.6
4.5.10,
4.5.12
4.5. 10,
4.5.13
NA .
1
0.67
'* 5
'2.7
Transfer Factors ;
Bv
,RCF
BaBMf
Bamilk
BCF
BAF
BSAF
Air-to-plant biotransfer factor (\jug pollutant/g plant
tissue DW]/[//g pollutant/g air]) v '
Ratio of concentration in the roots to concentration in
soil pore water ([f/g pollutant/g plant tissue FW]/[pg
pollutant/mL pore water])
.
Biotransfer factor for beef (day/kg)
Biotransfer factor for milk (day/kg) '
Fish bioconcentration factor (L/kg)
Fish bioaccumulation factor (L/kg)
Fish biota to sediment accumulation factor (unitless)
4.2.2,
4.4.3
4.3.2
4.4,4
4.5.5
4.5.14
4.5.15
4.5.16
130
1.7
1.9E-6
6.1E-7
2.6
NA
NA
Other Parameters
Fw
Fraction of wet deposition that adheres to plant
surfaces (dimensionless) ,
4.2.1,
4.4.2
0.-1
Health Benchmarks
CSF
RfD
Cancer Slope Factor (per mg/kg/day)
Reference Dose (mg/kg/day)
6.1.5,
6.2.5,
6.3.4,
6.4.4
6.1.6,
. 6.2.6,
6.3.5,
6.4.5
6.8E-1
1E-3
C-5-11
-------
DRAFT
April 15, 1994
Table 5.2.8. Chemical-Specific Inputs for
Di(n)octyl phthalate
Parameter
Definition
Equation
Value
Chemical/Physical Properties
ksg
Fv
Kd,
Kdsw
Kdbs ..
Soil loss constant due to degradation (yr1)
Fraction of pollutant air concentration present in the
vapor phase (dimensionless)
Soil-water partition coefficient (mL/g oFL/kg)
Suspended sediment-surface water partition coefficient
(L/kg)
Bottom sediment-sediment pore water partition
coefficient (L/kg)
4.1.2
4.2.2,
4.4.3
4.3.2,
4.5.5,
4.5.6
4.5,10, .
4.5.12
4.5.10,
4.5.13
NA
0.8
19,000,000
140,000,00
0
76,000,000
Transfer Factors
Bv
RCF
Babwf
Bam,!k
BCF
BAF
BSAF
Air-to-plant biotransfer factor ([/ug pollutant/g plant
tissue DW]/[//g pollutant/g air])
Ratio of concentration in the roots to concentration in
soil pore water (\jjg pollutant/g plant tissue FW]/[//g -
pollutant/mL pore water])
Biotransfer factor for beef (day/kg)
Biotransfer factor for milk (day/kg)
Fish bioconcentration factor (L/kg)
Fish bioaccumulation factor (L/kg)
Fish biota to sediment accumulation factor (unitless)
4.2.2,
4.4.3,
4.3.2
4.4.4
4.5.5
4.5.14
4.5.15
4.5.16
6.6E+.9
460,000
NA
NA
NA
66,000
NA
Other Parameters
Fw
Fraction of wet deposition that adheres to plant
surfaces (dimensionless)
4.2.1,
4.4.2
1
Health Benchmarks .
CSF
RfD
Cancer Slope Factor (per mg/kg/day)
Reference Dose (mg/kg/day)
6.1.5,
6.2.5,
6.3.4,
6.4.4 '
6.1.6,
6.2.6,
6.3.5,
6.4.5
NA
2E-2
C-5-12
-------
DRAFT
April 15,1994
Table 5.2.11. Chemical-Specific Inputs
- Nitrobenzene
for
Parameter
Chemical/Physical Properties
Definition
Kdsw
Kdbs
snii loss constant due to degradation (yr1)
Fraction of pollutant air. concentration present in the
vapor phase (dimensionless)^
Soil-water partition coefficient (mL/g or L/kg)
Suspended sediment-surface water partition coefficient
Bottom.sediment-sediment pore water partition
coefficient (L/kg)
-^~
Transfer Factors
L_
Bv
RCF
Air-to-plant biotransfer factor (b/9 pollutant/g plant
HC«IM> DWl/tod pollutant/g air])
Ratio of concentration in the roots to concentration in
Si pore water (b/9 pollutarit/g plant t,ssue FW]/b/9
pollutant/mL pore water])
Biotransfer factor for beef (day/kg)
. : -
Biotransfer factor for milk (day/kg)
"
hioconcentration factor (L/kg)
Fish bioaccumulation factor (L/kg)
"Fish biota to sediment accumulation factor (unitlessj
tore : . --
Fraction of wet deposition that adheres to plant
surfaces (dimensionless)
Health Benchmarks
CSF
RfD
Cancer Slope Factor (per mg/kg/day)
Reference Dose (mg/kg/day)
Equation
4.1.2
4.2.2,
.4.4.3
^^^iH^B
4.3.2,
4.5:5,
4.5.6
!^^"
4.5.10,
4.5.12
^^i
4.5.10,
4.5.13
4.2.2,
4.4.3
~"~"T"
4.3.2
Value
4.2.1,
4.4.2
6.1.5,
6.2.5,
6.3.4,
6.4.4
-«^-^^"
6.1.6,
6.2.6,
6.3.5,
6.4.5
0.6
0.1
NA
C-5-15
-------
DRAFT
April 15, 1994
Table 5.2.12. Chemical-Specific Inputs for
total PCBs
Parameter
Definition
Equation
Value
Chemical/Physical Properties -
ksg
Fv
Kd5
KdM
Kdbs
Soil loss constant due to degradation (yr1)
Fraction of pollutant air concentration present in the
vapor phase (dimensionless)
Soil-water partition coefficient (mL/g or L/kg)
Suspended sediment-surface water partition coefficient
(L/kg)
Bottom sediment-sediment pore water partition
coefficient (L/kg) J
4.1.2
4.2.2,
4.4.3
4.3.2,
4.5.5,
4.5.6
4.5.10,
4.5.12
4.5.10,
4.5.13
NA
1
4,300 .
32,000
17,000 '
Transfer Factors , :
Bv
RCF
Ba^,
Bami!k
BCF
BAF
BSAF
Air-to-plant biotransfer factor (fjt/g pollutant/g plant
tissue DW]/f//g pollutant/g air])
Ratio of concentration in the roots to concentration in
soil pore water (fo/g pollutant/g plant tissue FW]/[//g
pollutant/mL pore water])
Biotransfer factor for beef (day/kg)
Biotransfer factor for milk (day/kg)
Fish bioconcentration factor (L/kg)
Fish bioaccumulation factor (L/kg)
Fish biota to sediment accumulation factor (unitless)
4.2.2,
4.4.3
4.3.2
4.4.4
4.5.5
4.5.14
4.5.15
4:5.16
4,200
2,100
0.05
0.016
NA
NA
1.6
Other Parameters .'; .:...-:-'. '. , -'.." ". . .
Fw
Fraction of wet deposition that adheres to plant
surfaces (dimensionless)
4.2.1,
4.4.2
1
Health Benchmarks
CSF
RfD
Cancer Slope Factor (per mg/kg/day) ,
Reference Dose (mg/kg/day)
6.1.5,
6.2.5,
6.3.4,
6.4.4
6.1.6,
6.2.6,
6.3.5,
6.4.5
7.7
NA
C-5-16
-------
DRAFT
April 15, 1994
Table 5.2.13. Chemical-Specific Inputs
Pentachloronitrobenzene
for
Parameter
Definition
Chemical/Physical Properties
ksg
Fv
Ktjs
Kdsw
Kdbs
Soil loss constant due. to degradation (yr1)
Fraction of pollutant air concentration present in the
vapor phase (dimensionless)
Soil-water partition coefficient (mL/g or L/kg) .
Suspended sediment-surface water partition coefficient.
(L/kg)
Bottom sediment-sediment pore water partition
coefficient (L/kg)
Equation
4.1.2
4.2.2,
4.4.3
4.3.2,
4.5.5,
4.5.6
4.5.10,
4.5.12
4.5.10,
4.5.13
Value ||
NA
1
380
2,900
1,500
Transfer Factors '. ; .' --;":''. ;' v ' ' . '."':'*"--'>' > .:-.'.;;-.: '-- ...
Bv
RCF
Babeflf
Bamilk
BCF
' BAF
BSAF
Air-to-plant biotransfer factor (f//g pollutant/g plant
tissue DW]/[/t/g pollutant/g air])
Ratio of concentration in the roots to concentration in
soil pore water (|>g pollutant/g plant tissue FW]/fpg
pollutant/mL pore water]) ..:
Biotransfer factor for beef (day/kg).
Biotransfer factor for milk (day/kg)
Fish bioconcentration factor (L/kg)
Fish bioaccumulation factor (L/kg)
Fish biota to sediment accumulation factor (unitless)
4.2.2,
4.4.3
4.3.2
4.4.4
4.5.5
4.5.14
4.5.15
4.5.16
0.79
110
Q.0011
0.00035
140 '
NA
NA
Other Parameters- -" '.-^H.. ":.:^::.iJ$'-^'^"'--;, . ;oV v '''''- '.^-": . "''. . .' " ' ' '
Fw
Fraction of wet deposition that adheres to plant
surfaces (dimensionless)
4.2.1,
4.4.2
1
Health Benchmarks , "'. ' '.. .--':.. :::;: vu '''" '"'.' ' -""".-.''' :;':''. ' ' :-'', ' ' ' '' " "
CSF
RfD
Cancer Slope Factor (per mg/kg/day)
Reference Dose (mg/kg/day)
6.1.5,
6.2.5,
6.3.4,
6,4.4
6.1.6,
6.2.6,
6.3.5,
6.4.5
2.6h-1
bJ
G-5-17
-------
DRAFT
April 15, 1994
Table 5.2.14. Chemical-Specific Inputs for
Pentachlorophenol
Parameter
Definition
Equation
Value
Chemical/Physical Properties
ksg
Fv
Kd,
Kd,w
Kdb5 ' '
Soil loss constant due to degradation (yr"1)
Fraction of pollutant air concentration present in the
vapor phase (dimensionless) __
Soil-water partition coefficient (mL/g or L/kg)
Suspended sediment-surface water partition coefficient
(L/kg)
Bottom sediment-sediment pore water partition
coefficient (L/kg)
4.1.2
4.2.2,
4.4.3
4.3.2,
4.5.5,
4.5.6
4:5.10,
4.5.12
4.5.10,
4.5.13
NA
1
1,100
v 8,300
4,400
Transfer Factors .
Bv
RCF
Ba^,
Ba,,,^
BCF
BAF
BSAF
Air-to-plant biotransfer factor (f//g pollutant/g plant
tissue DW]/fo/g pollutant/g air])
Ratio of concentration in the roots to concentration in
soil pore water ([//g pollutant/g plant tissue FW]/[/t/g ,
pollutant/mL pore water])
Biotransfer factor for beef (day/kg)
Biotransfer factor for milk (day/kg)
Fish bioconcentration factor (L/kg)
Fish bioaccumulation factor (L/kg)
Fish biota to sediment accumulation factor (unitless)
4.2.2,
4.4.3
4.3.2
4.4.4
4.5.5
4.5.14
4.5.15
4.5.16
5,100
250
0.003
0.00096
NA
NA
NA
Other Parameters '"" , !.; . . /: :. ; ; ' . , ;
Fw
Fraction of wet deposition that adheres to plant
surfaces (dimensionless)
4.2.1,
4.4.2
1
Healt'h Benchmarks : I / " ;. : ': ; : ^ , . . :.
CSF
RfD
Cancer Slope Factor (per mg/kg/day)
Reference Dose (mg/kg/day)
6.1.5,
6.2.5, .
6.3.4, :
6.4.4
6.1.6,
6.2.6, .
6.3.5,
6.4.5
1.2E-1
3E-2
C-5-18
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DRAFT
April 15, 1994
Table 5,2.15. Chemical-Specific Inputs for
2,3,7,8-TCDDioxin Toxicity Equivalents
Parameter
Definition
Equation
Chemical/Physical Properties
ksg
-Fv
Kds
Kdsw
Kdbs
Soil loss constant due to degradation (yr*1)
Fraction of pollutant air concentration present in the
vapor phase (dimensioniess)
Soil-water partition coefficient (mL/g or L/kg)
Suspended sediment-surface water partition, coefficient
(L/kg).
Bottom sediment-sediment pore water partition
coefficient (L/kg)
4.1.2
4.2,2, .
4.4.3
4.3.2,
4.5.5,
4.5.6
4.5.10,
4.5.12
4.5.10,
4.5.13
Value
0,07
0.6
25,000
190,000
100,000
',..'
. .. .- "' .....-.-. . . II
Transfer Factors . II
Bv
RCF
Ba^,
Bami,k
BCF
BAF
BSAF
Air-to-plant biotransfer factor (f//g pollutant/g plant
tissue DW]/[//g pollutant/g air])
Ratio of concentration in the roots to concentration in
soil pore water (\pg pollutant/g plant tissue FW]/[//g
pollutant/mL pore water])
Biotransfer factor for beef (day/kg)
Biotransfer factor for milk (day/kg)
^Fish bioconcentration factor (L/kg);
Fish bioaccumulation factor (L/kg)
Fish biota to sediment accumulation factor (unitless)
4,2.2,
4.4.3
4.3.2
4.4.4
4.5.5 '
4.5:14
4.5.15
4.5.16
270,000
3,900 II
0.11
0.035.
NA
NA
0.09
Other Parameters '. . ..'.. .'::'.. '.'. """';->:':>' ":: :',.;: -;.- '.-..-' :"^' ' ''." ' ' -
Fw
Fraction of wet deposition that adheres to plant.
surfaces (dimensioniess) .. .,
4.2.1.
4.4.2
1
Health Benchmarks .;. ,
CSF
.RfD
'-
Cancer Slope Factor (per mg/kg/day)
Reference Dose (mg/kg/day)
6.1.5,
6.2.5,
6.3.4,
6.4.4
6.1.6,
'6.2.6,
. 6.3.5,
6.4.5
1.56E+5
NA
C-5-19
-------
-------
DRAFT April 15, 1994
' * * - - ,
6. RISK CHARACTERIZATION
Characterization of risk is the filial step of the screening analysis. In this step, for each
exposure scenario the health effects criteria or benchmarks are used in conjunction with dose
estimates which are calculated for each exposure pathway to arrive at the risk assessment
endpoints. The assessment endpoints of the screening analysis are as follows: a) the increased
probability of cancer in an individual over a lifetime, referred to as the excess lifetime individual
cancer risk (or simply, individual cancer risk) arising from both oral and inhalation routes of
exposure; b) for oral exposures, a measure of an individual's exposure to chemicals with
noncancer health effects relative to the reference dose (RfD), referred to as the hazard quotient;
c) for inhalation exposures, a hazard quotient relative to the reference concentration (RfC) in air;
and d) where appropriate, a hazard index which represents the combined hazard quotients for
those chemicals with the same noncancer health effects. Population risk is not an assessment
endpoint for the screening analysis. Although oral and inhalation routes of exposure are handled
separately hi the screening analysis, the individual risks associated with exposures to
carcinogenic chemicals are combined, for the oral and inhalation routes of exposure.
Indirect Exposures ' '
]For indirect exposures, a series of tables is provided for each exposure scenario. The tables
are used for estimating individual cancer risk and hazard quotients for the various chemicals and
for combining the cancer risks and hazard
quotients across pathways and chemicals M^^I^*""^"""^"""^^""""^""^^"^
as appropriate., Each equation is
presented on a separate table. The table Section 6.1 Subsistence Farmer
provides the mathematical form of the Tables 6.1.1. - 6.1.9.
equation, lists the chemicals for which the ' , .
equation is to be used, identifies the Section 6.2 Subsistence Fisher
parameters in the equation, and provides Tables 6.2.1.-6.2.9. '
the parameter values (or, if calculated, the
tables from which the values are Section 6.3 Adult Resident
obtained). It should be noted that not all Tables 6.3.1. - 6.3.8.
equations are used for all chemicals.
Specifically, calculations of individual Section 6.4 Child Resident
cancer risks, hazard quotients, and hazard Tables 6.4.1. - 6.4.8.
indices address different (albeit
overlapping) lists of chemicals. There are
four sets of tables presented in four "^"^l^^l^^^ll^^"Blli"1^"1^^^
sections as indicated in the text box.
For each of the four exposure scenarios, an estimate is made of the dose (or intake) of each
contaminant from all oral routes of exposure. Thus, for the subsistence farmer, the daily intake
of each contaminant is calculated for soil ingestion (Table 6.1.1), above-ground and
below-ground (i.e., root) vegetable .ingestion (Table 6.1.2), and beef and milk ingestion
(Table 6.1.3). The total daily oral intake of a contaminant is calculated by adding together the
intake from each pathway (Table 6.1.4). For each carcinogen, the excess lifetime individual
C-6-1
-------
DRAFT April 15, 1994
cancer risk is calculated using the cancer slope factor and total daily intake (Table 6.1.5). For
each chemical with noncancer health effects, a hazard quotient (HQ) is calculated using the RfD
and the total daily intake (Table 6.1.6). For the carcinogens, cancer risks are added across
chemicals (Table 6.1.7). For the subsistence farmer this involves adding the cancer risk from
all indirect exposures to eleven carcinogenic chemicals, namely arsenic, beryllium,
benzo(a)pyrene toxicity equivalents, bis(2-ethylhexyl) phthalate, 2,4-dinitro toluene, 2,6-dinitro
toluene, hexachlorobenzene, total PCBs, pentachloronitrobenzene, pentachlorophenol, and
2,3,7,8-TCDDioxin toxicity equivalents. For noncancer health effects, hazard quotients are
added across chemicals only when they target the same organ. Five chemicals, bis(2-ethylhexyl)
phthalate, hexachlorobenzene, pentachloronitrobenzene, pentachlorophenol, and di(n)octyl
phthalate, have systemic effects on the liver. Therefore, the hazard quotients from these five
chemicals are added together to calculate an overall hazard index for liver effects (Table. 6.1.8).
Three chemicals, 2,4-dinitro toluene, 2,6-dinitro toluene, and mercury, have systemic effects
on the central nervous system. Therefore, the hazard quotients from these three chemicals are
added together to calculate an overall hazard index for neurotoxic effects (Table 6.1.9).
Lead , ,
Childhood exposures to lead in'soil are assessed by comparing the estimated soil lead level at
the location of maximum combined (wet and dry) deposition (or an alternative location, as
discussed in Section 3.4, Exposure Locations) to the soil health-based level given in the
Implementation Guidance. Childhood and adult exposures to airborne lead are assessed by
comparing the maximum estimated air concentration (or the highest air concentration from an
alternative location, as discussed in Section 3.4, Exposure Locations) to the air health-based
level given in the Implementation Guidance. No hazard quotient is calculated and no other
exposure pathways are considered for lead.
Infant Exposure Through Breast Milk
The draft Addendum to the Indirect Exposure Document presents procedures for calculating
infant exposures to dioxins and other lipophilic compounds through ingestion of human breast
milk. The procedures are based on the intake of the contaminant by the mother. The exposure
to an infant from breast feeding can be presented as an average daily dose (ADD) or a lifetime
average daily dose (LADD). The ADD to the infant over a one year averaging time is predicted
to be much higher (e.g. 30 to 60 times higher) than the ADD-for the mother. However, if a
70 year averaging time is used, then the LADD to the infant is below the lower end of the range
for the mother's LADD. On a mass basis the cumulative dose to the infant through breast
feeding accou -is for between 4 to 12 percent of the lifetime dose (assuming background levels).
Although procedures exist for estimating an infant's exposure to a contaminant through
ingestion of breast milk, the health consequences of such exposures are not easily assessed. For
2,3,7,8-TCDD and other cancer causing agents with similar lipophilic properties, the typical
approach would be to use the LADD to calculate an individual lifetime cancer risk attributable
to the infant's exposure. This risk could be considered separately or in addition to other lifetime
exposures. The latter approach would increase lifetime cancer risk estimates for 2,3,7,8-TCDD
by about 10 percent over that of an adult without such exposures during infancy. However, for
C-6-2
-------
DRAFT April 15, 1994
2,3,7,8-TCDD and other similar chemicals, the health effects associated with elevated exposures
during the first year of life are not well characterized. It is possible that noncancer health
effects could be of much greater concern than cancer. Given the uncertainty hi how to interpret
the health effects attributable to an infant's exposure to contaminants through ingestion of breast
milk, exposures from breast milk are not included as part of the screening analysis. ,
The remainder of this section is "i^""^""^"^"""^"1^1'"^11^"
organized as follows. As indicated in the
previous text box, the tables for Sections 6.1 Indirect Exposures
characterizing risk from indirect through 6.4.
exposures for the four exposure scenarios
are given hi Section 6.1 through Section 6.5 Direct Inhalation
Section 6.4. Characterizing risk from Exposures
direct inhalation exposures is discussed
for air four exposure scenarios, in Section 6.6 Overall Direct and
Section 6.5, as indicated hi the text box. Indirect Cancer Risk
Finally,'Characterizing overall cancer risk
from both direct and indirect exposures is ' . ' .
discussed in Section 6.6. .""^
C-6-3
-------
DRAFT
6.1 Subsistence Farmer Scenario
April 15, 1994
This section provides the equations needed for characterizing risk from indirect exposures for
the subsistence farmer scenario. The folio whig equation tables are included:
Table 6.1.1. Soil Intake for Subsistence Farmer Scenario
Table 6.1.2. Above-Ground and Root Vegetable Intake for Subsistence Farmer Scenario
Table 6.1.3. Beef, and Milk Intake for Subsistence Fanner Scenario
Table 6.1.4. Total Daily Intake for Subsistence Farmer Scenario
Table 6.1.5. Cancer Risk for Individual Chemicals for Subsistence Farmer Scenario:
Carcinogens
Table 6.1.6. Hazard Quotient for Individual Chemicals for Subsistence Farmer Scenario:
NonCarcinogens .
Table 6.1.7. Total Cancer Risk for Subsistence Farmer Scenario: Carcinogens
Table 6.1.8. Hazard Index for Liver Effects for Subsistence Farmer Scenario: NonCarcinogens
Table 6.1.9. Hazard Index for Neurotoxic Effects for Subsistence Farmer Scenario:
NonCarcinogens .
C-6-4
-------
DRAFT April 15, 1994
- ' ' i
Table 6.1.1. Soil Intake for Subsistence Farmer Scenario
, Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl)phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
, , Equation
, . * soil
Parameter
U,
Sc
CR50il
""soil
=,Sc:CRsoil-Fsoil
Description
Daily intake of contaminant from soil (mg/day)
Soil concentration (mg/kg)
Consumption rate of soil (kg/day)
Fraction of consumed
soil contaminated (unitless)
Value
calculated
(see Table 4.1,1)
0.0001
1
C-6-5
-------
DRAFT
April 15, 1994
Table 6.1.2. Above-Ground and Root Vegetable Intake for Subsistence Farmer
Scenario
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl)phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
Iag=(Pd+Pv)-CRag'Fag
**-»'i.'c**'FH
Parameter
i«
Pd
Pv
CR^
^
'*
P«*
CR*
FbO
Description
Daily intake of contaminant from above-ground
vegetables (mg/day)
Concentration in above-ground vegetables due to
deposition (mg/kg)
Concentration in above-ground vegetables due to
air-to-plant transfer (mg/kg)
Consumption rate of above-ground vegetables (kg/day)
Fraction of above-ground vegetables contaminated
(unitless)
Daily intake of contaminant from root vegetables (mg/day)
Concentration in root vegetables (mg/kg)
Consumption rate of root veyetables (kg/day)
Fraction of root vegetables contaminated (unitless)
Value
calculated
(see Table
calculated
(see Table
4.2.1)
4.2.2)
0.024
0.95
calculated
(see Table
4.3.2)
0.0063
0.95
C-6-6
-------
DRAFT ., April 15, 1994
Table 6.1.3. Beef and Milk Intake for Subsistence Farmer Scenario
Chemicals
Arsenic ,
Beryllium .
Benzo(a)pyrene toxicity equivalents
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
- J - A ' '
beef -"-beef
J = A
,' 'milk Ami»f.
t
Parameter
'beef
A>eef
CRfceef
'beef
Ajnilk
CRmNk
Fmilk
CRbeef 'Fbeef
f*P P1
^^milk . milk
. Description
Daily intake of contaminant from
beef (mg/day)
Concentration in beef (mg/kg)
Consumption rate of beef (kg/day)
Fraction of beef contaminated (unitless) ,
Daily intake of contaminant from
milk (mg/day)
Concentration in milk (rng/kg)
Consumption rate of milk (kg/day)
Fraction of milk contaminated (unitless) '»...
Value
calculated
(see Table. 4.4.4)
0-1
0.44
calculated
(see Table 4.4.5)
0.3
0.40
C-6-7
-------
DRAFT April 15, 1994
Table 6.1.4. Total Daily Intake for Subsistence Farmer Scenario
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl)phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury ,
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
/-i. *<.*>* *'**/-
Parameter
I
'soit
U
k.
'b«f
'mt!k
Description
Total daily intake of contaminant (mg/day)
Daily intake of contaminant from soil (mg/day)
Daily intake of contaminant from above-ground
vegetables (mg/day)
Daily intake of contaminant from root vegetables (mg/day)
Daily intake of contaminant from beef (mg/day)
Daily intake of contaminant from milk (mg/day)
Value
calculated
(see Table 6.1.1)
calculated
(see Table 6.1.2)
calculated
(see Table 6.1.2)
calculated
(see Table 6.1.3)
calculated
(see Table 6.1.3)
C-6-8
-------
DRAFT
April 15, 1994
Table 6.1.5. Cancer Risk for Individual Chemicals for
Subsistence Fanner Scenario
.Carcinogens
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl) phthalate
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexachlorobenzene
total PCBs
Pentachlorpnitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Parameter
Cancer Risk
Equation
Cancer Risk
I -ED -EF -CSF
BW -AT -365
Description
Individual lifetime cancer risk (unitless)
Value
Total daily intake of contaminant (mg/day)
calculated ''
(see Table 6.1.4)
ED
Exposure duration (yr)
40
EF
Exposure frequency (day/yr)
350
BW
Body weight (kg)
70
AT
Averaging time (yr)
70
365
Units conversion factor (day/yr)
CSF
Oral cancer slope factor (per mg/kg/day)
chemical-specific
C-6-9
-------
DRAFT
April 15, 1994
Table 6.1.6. Hazard Quotient for individual Chemicals for
Subsistence Fanner Scenario
NonCarcinogehs
Chemicals
Arsenic
Beryllium
Bis (2-ethylhexyl) phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
Pentachloronitrobenzene
Pentachlorophenol
Equation
HQ
Parameter
HQ
1
BW
RfD
7
BW -RfD
Description
Hazard quotient (unitless)
Total daily intake of
contaminant (mg/day)
Body weight (kg)
Reference Dose (mg/kg/day)
Value
calculated
(see Table 6
1.4)
70
chemical-specific
C-6-1,0
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DRAFT
April 15, 1994
Table 6.1.7. Totall Cancer Risk for Subsistence Farmer Scenario
Carcinogens
Chemicals
Arsenic ,
Beryllium
Behzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl) phthalate
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexachlorobenzene
total PCBs ,
Pentachloronitrobenzene
Pentachlorophenol
. _ 2,3,7,8rTCDDioxin toxicity equivalents
Equation
Parameter
Total Cancer
Risk
Cancer Risk-
Total Cancer Risk
= £ Cancer Riskj
' ' ' ' ' '
Description Value
Total individual lifetime cancer risk for all chemicals .; :
(unitless) .
Individual lifetime cancer risk
(unitless)
for chemical carcinogen i calculated
(see Table 6.1.5)
C-6-11
-------
DRAFT
April 15, 1994
Table 6.1.8. Hazard Index for Liver Effects for Subsistence Farmer Scenario
NonCarcinogens
l
Chemicals
Bis(2-ethylhexyl phthalate)
Di(n)octyl phthalate
Hexachlorobenzene
Pentachloronitrobenzene
Pentachforophenol
Equation
-c-r«,
Parameter
HI,
HO,
Description
Hazard index for liver
effects (unitless)
Hazard quotient for chemical i with liver effects (unitless)
Value
calculated
(see Table 6.1.6)
C-6-12
-------
DRAFT
AprU 15, 1994
Table 6.1.9 Hazard Index for Neurotoxic Effects for
, Subsistence Farmer Scenario
NonCarcinogens
Chemicals
2,4-Dinitro toluene
2,6-Dinitro toluene
Mercury
Equation
Parameter
Hlneun,^
Description
Hazard index for neurotoxic effects (unitless)
Value
Hazard quotient for chemical i with neurotoxic effects
(unitless)
calculated
(see Table 6.;1.6)
C-6-13
-------
DRAFT
6.2 Subsistence Fisher Scenario
April 15, 1994
This section provides the equations needed for characterizing risk from indirect exposures for
the subsistence fisher scenario. The following equation tables are included:
Table 6.2.1. Soil Intake for Subsistence Fisher Scenario
Table 6.2.2. Above-Ground and Root Vegetable Intake for Subsistence Fisher Scenario
Table 6.2.3. Fish Intake for Subsistence Fisher Scenario
Table 6.2.4. Total Daily Intake for Subsistence Fisher Scenario
Table 6.2.5. Cancer Risk for Individual Chemicals for Subsistence Fisher Scenario:
Carcinogens
Table 6.2.6. Hazard Quotient for Individual Chemicals for Subsistence Fisher Scenario:
NonCarcinogens .
Table 6.2.7. Total Cancer Risk for Subsistence Fisher Scenario: Carcinogens
Table 6.2.8. Hazard Index for Liver Effects for Subsistence Fisher Scenario: NonCarcinogens
Table 6.2.9. Hazard Index for Neurotoxic Effects for Subsistence Fisher Scenario:
NonCarcinogens
C-6-14
-------
DRAFT April .15, 1994
Table 6.2.1. Soil Intake for Subsistence Fisher Scenario
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl)phthalate
1-,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexach lorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
' - . ' Pentachlorophenol ,
2,3,7,8-TCDDioxin toxicity equivalents
Equation
Parameter
Description
Value
'soil
Daily intake of contaminant from soil (mg/day)"
Sc
Soil concentration (rng/kg)
calculated
(see Table 4.1.1)
xsoil
Consumption rate of soil (kg/day)
0.0001
Fraction of consumed soil contaminated (unitless)
1
C-6-15
-------
DRAFT
AprU 15, 1994
Table 6.2.2. Above-Ground and Root Vegetable Intake for
Subsistence Fisher Scenario
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl)phthaiate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorotaenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
Iag=(Pd+Pv) -CRag-Fog
I*-pr*'CR«'F*
Parameter
U
Pd
Pv
CR.g
?«
I*
Pfb,
CR*
F*
Description
Daily intake of contaminant from above-ground
vegetables (mg/day)
Concentration in above-ground vegetables due to
deposition1 (mg/kg)
Concentration in above-ground vegetables due to
air-to-plant transfer (mg/kg)
Consumption rate of above-ground vegetables (kg/day)
Fraction of above-ground vegetables contaminated
(unitless)
Daily intake of contaminant from root vegetables (mg/day)
Concentration in root vegetables (mg/kg)
Consumption rate of root vegetables (kg/day)
Fraction of root vegetables contaminated (unitless)
Value
'
calculated
(see Table
calculated
(see Table
4.2.1)
4.2.2)
0.024
0.25
calculated
(see Table
4.3.2)
0.0063
0.25
C-6-16
-------
DRAFT April 15, 1994
Table 6.2.3. Fish Intake for Subsistence Fisher Scenario
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis (2-ethylhexyl) phthalate
1 ,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Methyl mercury . .
Nitrobenzene
totalPCBs
Pentachloronitrobenzene
2,3,7,8-TCDDioxin toxicity equivalents
Equation
^=c,;.cv^ ,.".....
Parameter
'fish
Cfish , :'
CRfish " =
Ffish .. ,
Description
Daily intake of contaminant from fish (mg/day)
Fish concentration
Consumption rate
(mg/kg) ' -
of fish (kg/day) -
Fraction of fish contaminated (unitless)
Value
calculated
(see Tables '
4.5.14, 4.5.15,
4.5.16)
0.140
1
C-6-17
-------
DRAFT April 15, 1994
Table 6.2.4. Total Daily Intake for Subsistence Fisher Scenario
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis (2-ethylhexyl) phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury/Methyl mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
~ soil ag tg Jish
Parameter
I
I-
t.
'*
u
Description
Total daily intake of contaminant (mg/day)
Daily intake of contaminant
Daily intake of contaminant
vegetables (mg/day)
Daily intake of contaminant
Daily intake of contaminant
from soil (mg/day)
from above-ground
from root vegetables (mg/day)
from fish (mg/day)
Value
calculated
(see Table 6.2.1)
calculated
(see Table 6
calculated
(see Table 6
calculated
(see Table 6
.2.2)
.2.2)
.2.3)
C-6-18
-------
DRAFT
April 15, 1994
Table 6.2.5. Cancer Risk for Individual Chemicals for
Subsistence Fisher Scenario
Carcinogens
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents.
Bis(2-ethylhexyl) phthalate
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexachlorobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
Cancer Risk =
I -ED -EF -CSF
BW -AT -365
Parameter
=^=^=
Cancer Risk
Description
Individual lifetime cancer risk (unitless)
Value
I
Total daily intake of contaminant (mg/day)
calculated
(see Table 6.2.4)
ED
Exposure duration (yr)
30
EF
Exposure frequency (day/yr)
350
BW
Body weight (kg)
70
AT
Averaging time (yr)
70
365
Units conversion factor (day/yr)
CSF
Oral cancer slope factor (per mg/kg/day)
chemical-specific
C-6-19
-------
DRAFT
April 15S 1994
Table 6.2.6. Hazard Quotient for Individual Chemicals for
Subsistence Fisher Scenario
NonCarcinogens
Chemicals
Arsenic
Beryllium
Bis (2-ethylhexyl) phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyi phthalate
Hexachlorobenzene
Mercury/Methyl mercury
Nitrobenzene
Pentachloronitrobenzene
Pentachlorophenol
Equation
HQ
Parameter
HQ
1
BW
RfD
/
BW-RfD
Description
Hazard quotient (unitless)
Total daily intake of
contaminant (mg/day)
Body weight (kg)
Reference Dose (mg/kg/day)
Value
calculated
(see Table 6.2.4)
70
chemical-specific
C-6-20
-------
DRAFT
AprU 15, 1994
Table 6.2.7. Total Cancer Risk for Subsistence Fisher Scenario
Carcinogens
Chemicals
Arsenic >
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl). phthalate
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexachlorobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxtn toxicity equivalents
. . Equation
Parameter
Total Cancer
Risk
Cancer Risk,
Total Cancer Risk
= JP Cancer Risk i
i . '
Description Value
Total individual lifetime cancer risk for all chemicals
(unitless) ,',.. ' : :
Individual lifetime cancer risk
(unitless)
for chemical carcinogen i calculated
, . " (see Table 6.2.5)
C-6-21
-------
DRAFT
April 15, 1994
Table 6.2.8. Hazard Index for Liver Effects for Subsistence Fisher Scenario
NonCarcinogens
Chemicals
Bis(2-ethylhexyl phthalate)
Di(n)octyl phthalate
Hexachlorobenzene
Pentachloronitrobenzene
Pentachlorophenol
Equation
*--?*>,
Parameter
HU
HQ,
Description
Hazard index for liver
effects
Hazard quotient for chemical
(unitless)
i with liver effects (unitless)
Value
calculated
(see Table 6.2.6)
C-6-22
-------
DRAFT
April 15, 1994
Table 6.2.9. Hazard Index for Neurotoxic Effects for
Subsistence Fisher Scenario
IMonCarcinogens
Chemicals
2,4-Dinitro toluene
2,6-Dinitro toluene
Mercury/Methyl mercury
Equation
fttneurotoiin = JET HQ 1 '
- i ' -
Parameter
.Description
Hlneuretoxin Hazard index for neurotoxic effects (unitless) ,
HO, Hazard quotient
, (unitless)
for chemical i with neurotoxic effects
Value
calculated
(see Table,6.2.6)
C-6-23
-------
DRAFT
6.3 Adult Resident Scenario
April 15, 1994
This section provides the equations needed for characterizing risk from indirect exposures for
the adult resident scenario. The following equation tables are included:
Table 6.3.1. Soil Intake for Adult Resident Scenario
Table 6.3.2. Above-Ground and Root Vegetable Intake for Adult Resident Scenario
Table 6.3.3. Total Daily Intake for Adult Resident Scenario
Table 6.3.4. Cancer Risk for Individual Chemicals for Adult Resident Scenario: Carcinogens
Table 6.3.5. Hazard Quotient for Individual Chemicals for Adult Resident Scenario:
NonCarcinogens ~
Table 6.3.6. Total Cancer Risk for Adult Resident Scenario: Carcinogens
Table 6.3.7. Hazard Index for Liver Effects for Adult Resident Scenario: NonCarcinogens
Table 6.3.8. Hazard Index for Neurotoxic Effects for Adult Resident Scenario:
NonCarcinogens
C-6-24
-------
DRAFT
April 15,1994
Table 6.3.1. Soil Intake for Adult Resident Scenario
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl)phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyi phthalate
Hexachlorobenzene
Mercury
Nitrobenzene.
total PCBs
Pentachlordnitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
Isoa=Sc-CRsoil-Fsoi{
Parameter
Description
Value
Daily intake of contaminant from soil (mg/day)
Sc
Soil concentration (mg/kg)
calculated'
(see table 4.1.1)
CPU,
Consumption rate of soil (kg/day)
0.0001
Fraction of consumed soil contaminated (unitless)
1
C-6-25
-------
DRAFT
April 15, 1994
Table 6.3.2. Above-Ground and Root Vegetable Intake for
Adult Resident Scenario
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl)phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Penta'chloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
I^-fPd+Pv) -CRag'Fag '
V-*V>CR*-F*
Parameter
'-
Pd
Pv
CR,3
FK
1*
Pr*
CR*
F*
Description
Daily intake of contaminant from above-ground
vegetables (mg/day)
Concentration in above-ground vegetables due to
deposition (mg/kg)
Concentration in above-ground vegetables due to
air-to-plant transfer (mg/kg)
Consumption rate of above-ground vegetables (kg/day)
Fraction of above-ground vegetables contaminated
(unitless)
Daily intake of 'contaminant from root vegetables (mg/day)
Concentration in root vegetables (mg/kg)
Consumption rate of root vegetables (kg/day)
Fraction of root vegetables contaminated (unitless)
Value
calculated
(see Table 4.2.1)
calculated
(see Table 4.2.2)
0.024
0.25
calculated
(see Table 4.3.2)
0.0063
0.25
C-6-26
-------
DRAFT April 15, 1994
fable 6.3.3. Total Daily Intake for Adult Resident Scenario
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
;Bis(2-ethylhexyi)phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene _
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene.
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
Parameter
Description
Value
Total daily intake of contaminant (mg/day) ,
'soil
Daily intake of contaminant from soil (mg/day)
calculated
(see Table 6.3,1)
ag
Daily intake of contaminant from above-ground
vegetables (mg/day)
calculated ,
(see Table 6.3.2)
'bfl
Daily intake.of contaminant from root vegetables (mg/day)
calculated
(see Table 6.3.2)
C-6-27
-------
DRAFT
AprU 15, 1994
Table 6.3.4. Cancer Risk for Individual Chemicals for Adult Resident Scenario
Carcinogens
Chemicals
Arsenic' . .
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl) phthalate
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexachlorobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
Cancer Risk =
Parameter
Cancer Risk
I
ED
EF
BW
AT
365
CSF
/ -ED -EF -CSF
BW -AT -365
Description
Individual lifetime cancer risk
(unitless)
Total daily intake of contaminant (mg/day)
Exposure duration (yr)
Exposure frequency (day/yr)
Body weight (kg) '
Averaging time (yr)
Units conversion factor (day/yr)
Oral cancer slope factor (per
mg/kg/day)
Value
calculated
(see Table 6.3.3)
30
350
70
70
chemical-specific
C-6-28
-------
DRAFT
April 15, 1994
Table 6.3,5. Hazard Quotient for Individual Chemicals for
Adult Resident Scenario
NonCarcinogens
Chemicals
Arsenic
Beryllium
Bis (2-ethylhexyl) phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
Pentachloronitrobenzene
Pentachlorophenol
Equation
HQ
Parameter
HQ
I
BW
RfD
I
BW-R/D
Description
Hazard quotient (unitless)'
Total daily intake of
contaminant (mg/day)
Body weight (kg)
Reference Dose (mg/kg/day) ,
Value
calculated .
(see Table 6.3.
3)
70
chemical-specific
C-6-29
-------
DRAFT
AprU 15, 1994
Table 6.3.6. Total Cancer Risk for Adult Resident Scenario
Carcinogens
Chemicals
Arsenic
Beryllium
Benzq(a)pyrene toxicity equivalents
Bis(2-ethylhexyl) phthalate
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexachlorobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2;3,7,8-TCDDioxin toxicity equivalents
Equation
Parameter
Total Cancer
Risk
Cancer Risk;
Total Cancer Risk
= £ Cancer Riski
i
Description Value
Total .individual lifetime cancer risk for all chemicals
(unitless)
Individual lifetime cancer risk
(unitless)
for chemical carcinogen i calculated
(see Table 6.3.4)
C-6-30
-------
DRAFT
April 15, 1994
Table 6.3.7. Hazard Index for Liver Effects for Adult Resident Scenario
NonCarcinogens
Chemicals
: Bis(2-ethylhexy! . phthalate)
. , Di(n)octyl phthalate
Hexachlorobenzene
Pentachloronitrobenzene
Pentachbrophenol
Equation
HI,. = YHQ
liver / * **;
'-_'
Parameter
Hl|iver
HQ,
Description Value
Hazard index for liver effects (unitless)
Hazard quotient for
chemical i with liver effects (unitless) calculated
(see Table 6.3.5)
C-6-31
-------
DRAFT
April 15, 1994
Table 6.3.8. Hazard Index for Neurotoxic Effects for Adult Resident Scenario
NonCarcinogens
Chemicals
2,4-Dinitro toluene
2,6-Dinitro" toluene
Mercury
Equation
neurotoxin ~ / *- i
i
Parameter
Description
HUuroioxm Hazard index for neurotoxic effects (unitless)
HQ, Hazard quotient
(unitless)
for chemical i with neurotoxic effects
Value
calculated
(see Table 6.3.5)
C-6-32
-------
DRAFT April .15,'1994
6.4 Child Resident Scenario
This section provides the equations needed for characterizing risk from indirect exposures for
the, child resident scenario. The following equation tables are included:
Table 6.4.1. Soil Intake for Child Resident Scenario ,
Table 6.4.2. Above-Ground and Root Vegetable Intake for Child Resident Scenario
Table 6.4.3. Total Daily Intake for Child Resident Scenario
Table 6.4.4. Cancer Risk for Individual Chemicals for Child Resident Scenario: Carcinogens
Table 6.4.5. Hazard Quotient for Individual Chemicals .for Child Resident Scenario:
NonCarcinogens
Table 6.4.6. Total Cancer Risk for Child Resident Scenario: Carcinogens
Table, 6.4.7. Hazard Index for Liver Effects for Child Resident Scenario: NonCarcinogens
Table 6.4.8. Hazard Index for Neurotoxic Effects for Child Resident Scenario:
NonCarcinogens
C-6-33
-------
DRAFT
AprU 15, 1994
Table 6.4.1. Soil Intake for Child Resident Scenario
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl)phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
*soil
Parameter
'toil
Sc
CRSC!l
F,OI,
=Sc-CRsoil-Fsoil
Description
Daily intake of contaminant from soil (mg/day)
Soil concentration (mg/kg)
Consumption rate of soil (kg/day)
Fraction of consumed
soil contaminated (unitless)
Value
calculated
(see Table 4,1.1)
0.0002
1
C-6-34
-------
DRAFT
April 15, 1994
Table 6.4.2. Above-Ground and Root Vegetable Intake for
Child Resident Scenario
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl)phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury ,
Nitrobenzene
total PCBs
__ ' Pentacnloronitrobenzene . ..'
Pentachlorophenql
2,3,7,8-TCDDioxin toxicity equivalents
Equation
7 D« /~^ D C1 ' ...',
t t~j \~fi\. r *
I) JT fog OS OS
Parameter
«,
Pd
Pv
CRag
F,. .
m
-X
CRbg
^ .
Description
Daily intake of contaminant from above-ground
vegetables (mg/day) .
Concentration in above-ground vegetables due to
deposition (mg/kg)
Concentration in above-ground vegetables due to
air-to-plant transfer (mg/kg)
Consumption rate of above-ground vegetables (kg/day)
Fraction of above-ground vegetables contaminated
(unitless)
Daily intake of contaminant from root vegetables (mg/day)
Concentration in root vegetables (mg/kg) ,
Consumption rate of root vegetables (kg/day)
Fraction of root vegetables contaminated (unitless)
Value
calculated
(see Table 4.2.1)
calculated
(see Table 4.2.2)
0.005
0.25
calculated
(see Table 4.3.2)
0.0014
0.25
C-6-35
-------
DRAFT - : April 15, 1994
Table 6.4.3. Total Daily Intake for Child Resident {Scenario
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl)phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene -
2,6-Dinitro toluene 2,
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
total PCBs
Pentachloronitrobenzene
Pentachlorophenol
3,7,8-TCDDioxin toxicity equivalents
Equation
soil ag bg
Parameter
I
U
I,
>*
Description
Total daily intake of contaminant (mg/day)
Daily intake of contaminant from soil
(mg/day)
Daily intake of contaminant from above-ground
vegetables (mg/day)
Daily intake of contaminant from root
vegetables (mg/day)
Value
calculated
(see table 6.4
calculated
(see Table 6.4
calculated
(see Table 6.4
1)
2)
2)
C-6-36
-------
DRAFT
April 15, 1994
Table 6.4.4. Cancer Risk for Individual Chemicals for Child Resident Scenario
Carcinogens'
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl), phthalate
2,4-Dinitro toluene
2,6-Dinitro toluene
Hexach lorobenzene
total RGBs
Pentachloronitrobenzene ,
Pentachlorophenol
2,3,7,8-TCDDioxtn toxicity equivalents
Equation .
Cancer
Parameter
Cancer Risk .
1
ED
EF
BW
AT
365
CSF
Risk =
I '-ED -EF -CSF
BW -AT -365
Description
Individual lifetime cancer risk (unitless)
Total daily intake of
contaminant (mg/day):
Exposure duration (yr)
Exposure frequency
(day/yr)
Body weight (kg) ,
Averaging time (yr) .
Units conversion factor (day/yr)
Oral cancer slope factor (per mg/kg/day)
Value
calculated
(see Table 6,4.3)
6
350
15
70
chemical-specific
C-6-37
-------
DRAFT
April 15, 1994
Table 6.4.5. Hazard Quotient for Individual Chemicals for
Child Resident Scenario
NonCarcinogens
Chemicals
Arsenic
Beryllium -
Bis (2-ethylhexy!) phthalate
1,3-Dinitro benzene
2,4-Dinitro toluene
2,6-Dinitro toluene
Di(n)octyl phthalate
Hexachlorobenzene
Mercury
Nitrobenzene
Pentachloronitrobenzene
Pentachlprophenol
Equation
HQ
Parameter
HQ
1
BW
RfD
/
BW-RfD'
Description.
Hazard quotient (unitless)
Total daily intake of
contaminant (mg/day)
Body weight (kg)
Reference Dose (mg/kg/day)
Value
calculated
(see Table 6.4.3)
15
chemical-specific
C-6-38
-------
DRAFT
April 15, 1994
Table 6.4.6. Total Cancer Risk for Child Resident Scenario
Carcinogens
Chemicals
Arsenic
Beryllium
Benzo(a)pyrene toxicity equivalents
Bis(2-ethylhexyl) phthalate
2,4-Dinitro toluene
2,6-Dinitro toluene
. Hexachlorobenzene
total PCBs
Pentachloronitrobenzene
Pentachldrophenol
2,3,7,8-TCDDioxin toxicity equivalents
Equation
Total Cancer Risk = £ Cancer Risk,
Parameter
Description
Value
Total Cancer
Risk
Total individual lifetime cancer risk for all chemicals
(unitless) . ,
Cancer Risk,
Individual lifetime cancer risk for chemical carcinogen i
(unitless) . , ^
calculated
(see Table 6.4.4)
C-6-39
-------
DRAFT
April 15, 1994
Table 6.4.7. Hazard Index for Liver Effects for Child Resident Scenario
NonCarcinogens
Chemicals
Bis(2-ethylhexyl phthalate)
Di(n)octyl phthalate
Hexachlorobenzene
Pentachloronitrobenzene
Pentachlorophenol
Equation
TTT T^ £//")
/
Parameter
H'hver
HO,
Description
Hazard index for liver effects
Hazard quotient for
chemical
(unitless)
i with liver effects (unitless)
Value
calculated
(see Table 6.4.5)
C-6-40
-------
DRAFT
April. 15, 1994
Table 6.4.8. Hazard Index for Neurotoxic Effects for Child Resident Scenario
INonCarcinogens
, Chemicals
2,4-Dinitro toluene
2,6-Dinitro toluene
Mercury
,
Equation
" - - - . - -
H1nmr0to^-^HQi ;
' . '
Parameter
Hlpe.ro.oxin ' Hazard indBX for
Description
neurotoxic effects (unitless)
HQi Hazard quotient for chemical i with neurotoxic effects
(unitless)
Value
calculated
(see Table 6.4.5)
C-6-41-
-------
DRAFT April 15, 1994
6.5 Direct Inhalation Exposures
Characterization of risks from direct inhalation exposures is necessary to complete the
screening analysis. Risks should be characterized from all chemicals emitted by the combustion
source that have inhalation health criteria or benchmarks. The Implementation Guidance
provides a list of chemicals in combustion emissions that should be addressed as part of the
screening analysis. Although a number of the chemical compounds identified hi the
Implementation Guidance do not have appropriate health criteria or benchmarks for assessing
inhalation exposures, all chemical compounds 'that do have unit risk factors (URF's),
carcinogenic slope factors (CSF's), or reference Concentrations (RfC's) in IRIS6 or HEAST7
should be included hi the screening analysis.
The excess lifetime individual cancer risk from direct inhalation of a chemical carcinogen is
calculated from the unit risk factor (URF) for each exposure scenario as follows:
Cancer Risk (ink) = C(air). URF(inh)i 6-1
where: . '
Cancer Risk(inh)hiiJ = Excess lifetime cancer risk via inhalation (unitless), chemical i
(i=l..n), exposure scenario j (j = l..4)
C^jj = Concentration hi air 0*g/m3, from COMPDEP), chemical i
(i=l..n), exposure scenario j (j = 1..4)
URF(inh)i = Inhalation unit risk factor (per jig/m3), chemical i (i== 1. .n)
Alternatively, if a carcinogenic slope factor (CSF) is available for the chemical, the lifetime
individual cancer risk is calculated from the average daily intake via inhalation (ADI). The
average daily intake via inhalation is calculated for each exposure scenario as follows:
C(cnr).,'-IR, ET EF -ED. -0.001 , -
- " ' 6
6 Integrated Risk Information System on-line database, as described in the Federal Register of
February 25, 1993 (58 FR 11490). .
7 Health Effects Assessment Summary Tables, Annual Update and Supplements thereto
(U.S. EPA, 1993d, 1993e, and 1993f).
C-6-42
-------
DRAFT
April 15, 1994
where:
ADI(inh)y
IR,
ET
EF
AT
0.001
Average daily intake via inhalation (mg/kg/day), chemical i (i=l..m),
exposure scenario j (j = l..4) ,
Ambient air concentration (pig/m3, from COMPDEP), chemical i
(i=l..m), exposure scenario j (j 1..4)
Inhalation rate (m3/hr), exposure scenario j(j = l.. 4)
Exposure time (24 hours/day)
Exposure frequency (350 days/yr)
Exposure duration (years)^ exposure scenario j (j'= 1. .4)
Body weight (kg), exposure scenario j (j = l..4)
Averaging time (25,550 days)
Units conversion factor
The averaging tune for the ADI is taken as a lifetime (i.e., 70 years). .The exposure parameter
values for Equation 6-2 that depend on the particular exposure scenario are given hi Table 6.5.
~~ i '
Table 6.5. Exposure Parameter Values for Average Daily Intake via Inhalation
Exposure Parameter
Inhalation Rate
(m3/hr)
Exposure Duration .
(years)
Body Weight (kg)
Exposure
Subsistence
Farmer
1.0
40 '
70
Subsistence
Fisher
1.0
30
70
Scenario .. '
Adult Resident
1.0
30
70
Child Resident
0.2
6
15
The excess lifetime individual cancer risk is then calculated from the carcinogenic slope.factor
(CSF),and the average daily intake via inhalation. For each exposure scenario:
Cancer Risk(inh)ii = ADI(inh) CSF(inh)i
6-3
where:
Cancer Risk(inh)y =
CSF(inh)i
Excess lifetime cancer risk via inhalation (unitless), chemical i
(i=1. .in), exposure scenario j (j = 1. .4)
Average daily intake via inhalation (mg/kg/day), chemical i
(i=l..m), exposure scenario j (j=1..4)
Inhalation carcinogenic slope, factor (per mg/kg/day), chemical i
C-6-43
-------
DRAFT
April 15, 1994
The total cancer risk to the individual via inhalation is estimated by summing the lifetime
individual cancer risk for all chemicals that are carcinogenic via the inhalation route of exposure:
Total Cancer Risk (ink) = £ Cancer Risk (ink)
'
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DRAFT April 15, 1994
Section 6.6 Overall Direct and Indirect Cancer Risk
To determine the overall carcinogenic risk from all exposure pathways, both direct inhalation
and indirect exposure pathways/the total cancer risks for the indirect pathways (as calculated
for each exposure scenario in Table 6.1.7, Table 6.2.7, Table 6.3.7, and Table 6.4.7) are added
to the total cancer risk via inhalation. For each exposure scenario:
Overall Cancer Risk = Total Cancer Risk(inh)j + Total \Cancer Risk (oral). 6-7
where:
Overall Gancer Riskj = Overall excess lifetime cancer risk via all routes of exposure
(unitless), exposure scenario j (] = !..4)
Total Cancer Risk(inh)j = Total excess lifetime cancer risk via inhalation (unitless,
from! Equation 6-4) exposure scenario j (j = l..4)
Total Cancer Risk(oral)j = Total excess lifetime cancer risk via indirect (i.e., oral)
exposures (unitless, from Tables 6.x.7), exposure scenario j
(x=j = 1..4) -
C-6-45
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DRAFT April 15, 1994
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