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vvEPA
United States Environmental
Protection Agency
Office of Chemical Safety
and Pollution Prevention
Draft Risk Evaluation for
1-Bromopropane
1-BP Supplemental File:
Supplemental Information on Consumer Exposure Assessment
CASRN: 106-94-5
CH
August 2019
NOTICE: This information is distributed solely for the purpose of pre-dissemination peer review under
applicable information quality guidelines. It has not been formally disseminated by EPA. It does not
represent and should not be construed to represent any Agency determination or policy. It is being
circulated for review of its technical accuracy and science policy implications.

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Table of Contents
1	Consumer Exposure	3
1.1	Consumer Exposure	3
1.2	Consumer Modeling	4
1.2.1	CEM Approach	5
1.2.1.1 CEM Inputs	8
1.2.2	MCCEM Approach	11
1.2.2.1 MCCEM Inputs	12
1.2.2.1.1	Emission Rate	12
1.2.2.1.2	Product Amount and Duration of Use	13
1.2.2.1.3	Zone Definitions, Volumes, and Airflow Rates	13
1.2.3	IECCU Approach	14
1.2.4	Consumer Exposure Results	15
2	Model Sensitivity Analyses	16
2.1 CEM Sensitivity Analysis	16
3	References	17
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1 Consumer Exposure
The United States Environmental Protection Agency (U.S. EPA) evaluated 1-Bromopropane (1-
BP) exposure resulting from the use of consumer products. The U.S. EPA utilized a modeling
approach to evaluate exposure because chemical specific personal monitoring data was not
identified for consumers during data gathering and literature searches performed as part of
Systematic Review.
1.1 Consumer Exposure
Consumer products containing 1-BP are readily available at retail stores and via the internet for
purchase and use. Use of these products can result in exposures of the consumer user and
bystanders to 1-BP during and after product use. Consumer exposure can occur via inhalation,
dermal, and oral routes.
Consumer products containing 1-BP were identified through review and searches of a variety of
sources, including the National Institutes of Health (NIH) Household Products Database, various
government and trade association sources for products containing 1-BP, company websites for
Safety Data Sheets (SDS), Kirk-Othmer Encyclopedia of Chemical Technology, and the internet
in general. Identified consumer products were then categorized into nine consumer use groups
considering (1) consumer use patterns, (2) information reported in SDS, (3) product availability
to the public, and (4) potential risk to consumers. Table 1-1 summarizes the nine consumer use
groups evaluated as well as the routes of exposure for which they were evaluated.
Table 1-1 Consumer Uses and Routes of Exposure Assessed
Consumer Uses
Routes of Exposure
1.	Adhesive Accelerant (Liquid Pump Spray)
2.	General Purpose Spray Cleaner (Liquid Spray/Aerosol)
3.	Spot Cleaner and Stain Remover (Liquid Spray/Aerosol)
4.	Mold Cleaning and Release Product (Liquid Spray/Aerosol)
5.	General Cleaners and Degreasers (Liquid Spray/Aerosol)
6.	Electronics Degreasers (Liquid Spray/Aerosol)
Inhalation and Dermal
7.	Coin and Scissors Cleaner (Liquid Bath)
8.	Automobile AC Flush (Liquid)
Inhalation and Dermal
9. Insulation (Off-gassing)
Inhalation
The U.S. EPA evaluated acute inhalation and dermal exposure of the consumer to 1-BP for this
evaluation. Acute inhalation exposure is an expected route of exposure for all nine consumer use
groups. Acute dermal exposure is a possible route of exposure for the first eight consumer use
groups, however, this evaluation only considered dermal exposure for three of the eight
consumer use groups (General Cleaners and Degreasers, Coin and Scissors Cleaner, and
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Automobile AC Flush) due to the possibility of continuous supply of product against the skin.
The U.S. EPA does not expect exposure under any of the nine consumer use groups evaluated to
be chronic in nature and therefore does not present chronic exposure for consumers. The U.S.
EPA does not expect oral exposure to occur under any of the nine consumer use groups
evaluated and therefore did not evaluate the oral route of exposure.
The U.S. EPA evaluated inhalation and dermal exposure for the consumer user and evaluated
only inhalation exposure for a non-user (bystander) located within the residence during product
use. The consumer user consisted of three age groups (adult, greater than 21 years of age; Youth
A, 16-20 years of age; and Youth B, 11-15 years of age) which includes the susceptible sub-
population woman of childbearing age. The bystander can include individuals of any age (infant
through elderly).
1.2 Consumer Modeling
Three models were used to evaluate consumer exposures, EPA's Consumer Exposure Model
(CEM), EPA's Multi-Chamber Concentration and Exposure Model (MCCEM), and EPA's
Indoor Environment Concentrations in Buildings with Conditioned and Unconditioned Zones
(IECCU) model. A general overview and some details about each of these models are provided
in the respective sections below. Readers can learn more about equations within the models,
detailed input and output parameters, pre-defined scenarios, default values used, and supporting
documentation by reviewing the CEM user guide (U.S. EPA 2019a). CEM user guide
appendices (U.S. EPA 2019b). MCCEM user guide (U.S. 2019). and IECCU user guide (U.S.
EPA. 2019c). Table 1-2 summarizes the specific models used for each consumer use group and
the associated routes of exposure evaluated.
Table 1-2 Models Used for Routes of Exposure Evaluated
Consumer Uses
Routes of Exposure
Inhalation
Dermal
1. Adhesive Accelerant
CEM

2. General Purpose Spray Cleaner
CEM

3. Spot Cleaner and Stain Remover
CEM

4. Mold Cleaning and Release Product
CEM

5. General Cleaners and Degreasers
CEM
CEM
6. Electronics Degreasers
CEM

7. Coin and Scissors Cleaner
MCCEM
CEM
8. Automobile AC Flush
MCCEM
CEM
9. Insulation
IECCU

Each model is peer reviewed. Default values within CEM and MCCEM are a combination of
high end and mean or central tendency values derived from U.S. EPA's Exposure Factors
Handbook (U.S. EPA. 2011). literature, and other studies. IECCU currently does not provide
default values for input parameters, instead, inputs are derived from empirical data or modeled
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estimates including U.S. EPA's Exposure Factors Handbook (U.S. EPA. 2011). literature, and
other studies.
1.2.1 CEM Approach
CEM is a deterministic model which utilizes user provided input parameters and various
assumptions (or defaults) to generate exposure estimates. In addition to pre-defined scenarios,
which align well with the first six consumer uses identified in Table 1-1, CEM is peer reviewed,
provides flexibility to the user by allowing modification of certain default parameters when
chemical-specific information is available, and does not require chemical-specific emissions data
(which may be required to run more complex indoor/consumer models).
CEM predicts indoor air concentrations from consumer product use through a deterministic,
mass-balance calculation derived from emission calculation profiles within the model. There are
six emission calculation profiles within CEM (E1-E6) which are summarized in the CEM users
guide and associated appendices. If selected, CEM provides a time series air concentration
profile for each run. These are intermediate values produced prior to applying pre-defined
activity patterns.
CEM uses a two-zone representation of the building of use when predicting indoor air
concentrations. Zone 1 represents the room where the consumer product is used. Zone 2
represents the remainder of the building. Each zone is considered well mixed. CEM allows
further division of Zone 1 into a near field and far field to accommodate situations where a
higher concentration of product is expected very near the product user when the product is
initially used. Zone 1-near field represents the breathing zone of the user at the location of the
product use while Zone 1 far field represents the remainder of the Zone 1 room.
Inhalation exposure is estimated in CEM based on zones and pre-defined activity patterns. The
simulation run by CEM places the product user within Zone 1 for the duration of product use
while the bystander is placed in Zone 2 for the duration of product use. Following the duration of
product use, the user and bystander follow one of three pre-defined activity patterns established
within CEM, based on modeler selection. The selected activity pattern takes the user and
bystander in and out of Zone 1 and Zone 2 for the period of the simulation. The user and
bystander inhale airborne concentrations within those zones, which will vary over time, resulting
in the overall estimated exposure to the user and bystander.
CEM contains two methodologies for estimating dermal exposure to chemicals in products, the
permeability method (P-DER1) and the fraction absorbed method (A-DER1). Each of these
methodologies further has two model types, one designed for dermal exposure from use of a
product (P-DERIa and A-DERla), the other designed for dermal exposure from use of an article
(P-DERlb and A-DERlb). Each methodology has associated assumptions, uncertainties, and
data input needs within the CEM model. Both methodologies factor in the dermal surface area to
body weight ratio and weight fraction of chemical in a consumer product.
The permeability model is based on the ability of a chemical to penetrate the skin layer once
contact occurs. The permeability model assumes a constant supply of chemical, directly in
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contact with the skin, throughout the exposure duration. The ability to use the permeability
method can be beneficial when chemical-specific skin permeability coefficients are available in
the scientific literature. However, the permeability model within CEM does not consider
evaporative losses when it estimates dermal exposure and therefore may be more representative
of a dermal exposure resulting from a constant supply of chemical to the skin due to a barrier or
other factor that may restrict evaporation of the chemical of interest from the skin (a product
soaked rag against the hand while using a product), or immersion of a body part into a pool of
product. Either of these examples has the potential to cause an increased duration of dermal
contact and permeation of the chemical into the skin resulting in dermal exposure.
The fraction absorbed method is based on the absorbed dose of a chemical. This method
essentially measures two competing processes, evaporation of the chemical from the skin and
penetration of the chemical deeper into the skin. This methodology assumes the application of
the chemical of concern occurs once to an input thickness and then absorption occurs over an
estimated absorption time. The fraction absorbed method can be beneficial when chemical
specific fractional absorption measurements are available in the scientific literature. The
consideration of evaporative losses by the fraction absorbed method within CEM may make this
model more representative of a dermal exposure resulting from scenarios that allow for
continuous evaporation and typically would not involve a constant supply of product against the
skin for dermal permeation. Examples of such scenarios include spraying a product onto a mirror
and a small amount of mist falling onto an unprotected hand.
All consumer use groups identified in Table 1-2 and evaluated with CEM used CEM's E3
emission model and profile for inhalation exposure. This model and profile assume a percentage
of a consumer product used is aerosolized (e.g. overspray) and therefore immediately available
for uptake by inhalation. The associated inhalation model within CEM is P-INH2. The U.S. EPA
also used the near-field and far-field option within CEM for all consumer use groups evaluated
with CEM. All three consumer use groups evaluated for dermal exposure with CEM used the
permeability method. The associated dermal model within CEM is P-DERlb.
In an effort to characterize a potential range of consumer inhalation exposures, the EPA varied
three key parameters within the CEM model while keeping all other input parameters constant.
The key parameters varied were duration of use per event (minutes/use), amount of chemical in
the product (weight fraction), and mass of product used per event (gram(s)/use). These key
parameters were varied because they provide representative consumer behavior patterns for
product use. Additionally, CEM is highly sensitive to two of these three parameters (duration of
use and weight fraction) which can be seen in the sensitivity analysis performed on CEM and
included within the CEM users guide and associated CEM user guide appendices. Finally, all
three parameters had a range of documented values within literature identified as part of
Systematic Review allowing the EPA to evaluate inhalation exposures across a spectrum of use
conditions.
To characterize a potential range of consumer dermal exposures, the EPA varied two key
parameters within CEM while keeping all other input parameters constant. The key parameters
varied for dermal exposure evaluation were weight fraction and duration of use per event. The
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mass of product used is not a factor in the dermal exposure equations within CEM and therefore
was not varied.
Once the data was gathered for the parameters varied, modeling was performed to cover all
possible combinations of these three parameters. This approach results in a maximum of 27
different iterations for each consumer use. Table 1-3 summarizes these 27 combinations.
Table 1-3 Example Structure of CEM Cases for Each Consumer Use Group Scenario Modeled
CEM Set
Scenario Characterization
(Duration-Weight Fraction-
Product Mass)
Duration of
Product Use Per
Event (inin/use)
[not scalable]
Weight Fraction of
Chemical in Product
(unitless)
[scalable]
Mass of Product Used
(g/use)
[scalable]

Case 1: Low-Low-Low


Low

Case 2: Low-Low-Mid

Low
Mid

Case 3: Low-Low-High


High
Set 1
Case 4: Low-Mid-Low


Low
(Low
Intensity
Case 5: Low-Mid-Mid
Low
Mid
Mid
Use)
Case 6: Low-Mid-High


High

Case 7: Low-High-Low


Low

Case 8: Low-High-Mid

High
Mid

Case 9: Low-High-High


High

Case 10: Mid-Low-Low


Low

Case 11: Mid-Low-Mid

Low
Mid

Case 12: Mid-Low-High


High
Set 2
Case 13: Mid-Mid-Low


Low
(Moderate
Intensity
Case 14: Mid-Mid-Mid
Mid
Mid
Mid
Use)
Case 15: Mid-Mid-High


High

Case 16: Mid-High-Low


Low

Case 17: Mid-High-Mid

High
Mid

Case 18: Mid-High-High


High
Set 3
Case 19: High-Low-Low
High
Low
Low

Case 20: High-Low-Mid

Mid
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(High
Intensity
Use)
Case 21: High-Low-High


High
Case 22: High-Mid-Low


Low

Case 23: High-Mid-Mid

Mid
Mid

Case 24: High-Mid-High


High

Case 25: High-High-Low


Low

Case 26: High-High-Mid

High
Mid

Case 27: High-High-High


High
The U.S. EPA utilized an option within CEM to obtain the intermediate time series concentration
values from each model run. These values are calculated for every 30 seconds (0.5 minute)
period for each zone for the entire length of the model run. This approach allowed the U.S. EPA
to perform post-processing within Excel to determine personal concentration exposures for the
user and bystander. This post-processing was conducted by independently assigning the Zone 1,
Zone 2, and outside (zero) concentration to the user and bystander. These zone concentrations
were assigned based on the pre-defined activity patterns within CEM. Time-weighted average
concentration exposures were then calculated from the personal exposure time series to develop
estimates for all iterations within each consumer use category. Time weighted average (TWA)
concentrations were determined for 1 hour, 3 hours, 8 hours, and 24 hours, although for this
evaluation the 24-hour TWA concentration was utilized based on health endpoints used to
calculate risks.
1.2.1.1 CEM Inputs
Numerous input parameters are required to generate exposure estimates within CEM. These parameters
include physical chemical properties of the chemical of concern, product information (product density,
water solubility, vapor pressure, etc.), model selection and scenario inputs (pathways, CEM emission
model(s), emission rate, activity pattern, product user, background concentration, etc.), product or article
property inputs (frequency of use, aerosol fraction, etc.), environmental inputs (building volume, room of
use, near-field volume in room of use, air exchange rates, etc.), and receptor exposure factor inputs (body
weight, averaging time, exposure duration inhalation rate, etc.). Several of these input parameters have
default values within CEM based on the pre-defined use scenario selected. Default parameters within
CEM are a combination of high end and mean or median values found within the literature or based on
data taken from U.S. EPA's Exposure Factors Handbook (U.S. EPA. 2011). Details on those parameters
can be found within the CEM User Guide (U.S. EPA. 2019a) and associated User Guide Appendices
(U.S. EPA. 2019b) or can be cross referenced to U.S. EPA's Exposure Factors Handbook (U.S. EPA.
2011). As discussed earlier, while default values are initially set in pre-defined use scenarios, CEM has
flexibility which allows users to change certain pre-set default parameters and input several other
parameters.
Key input parameters for the consumer uses evaluated with CEM as identified in Table 1-2 are discussed
below. Detailed spreadsheets of all input parameters used for each consumer use evaluated with CEM are
provided in 1-BP Supplemental File: Information on Consumer Exposure Assessment Model Input
Parameters (EPA. 2019a).
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Physical chemical properties of 1-BP were kept constant across all consumer uses and iterations
evaluated. A chemical-specific skin permeability coefficient of 9.05E-03 centimeters per hour was found
in literature (DHHS. 2017) and utilized for all scenarios modeled for dermal exposure.
Model selection is discussed in the previous section. Exposure scenario inputs were also kept constant
across all consumer uses and iterations. Emission rate was estimated using CEM. The activity pattern
selected within CEM was stay-at-home. The start time for product use was 9:00 AM and the product user
was adult (>21 years of age) and Youth (11-15 years of age and 16-20 years of age). The background
concentration of 1-BP for this evaluation was considered negligible and therefore set at zero milligrams
per cubic meter.
Frequency of use for acute exposure calculations was held constant at one event per day. The aerosol
fraction (amount of overspray immediately available for uptake via inhalation) selected within CEM for
all consumer uses evaluated was six percent. Building volume used for all consumer uses was the default
value for a residence within CEM (492 cubic meters). The near-field volume selected for all consumer
uses was one cubic meter. Averaging time for acute exposure was held constant at one day.
Certain model input parameters were varied across consumer use scenarios but kept constant for all model
iterations run for a specific consumer use. These input parameters include product density, room of use,
and pre-defined product scenarios within CEM. Product densities were extracted from product-specific
SDS. Room of use was extracted from a published EPA directed survey of consumer behavior patterns in
the United States titled Household Solvent Products: A National Usage Survey (U.S. EPA. 1987) (Westat
Survey), identified in the literature search as part of systematic review. The Westat survey is a nationwide
survey which provides information on product usage habits for thirty-two different product categories.
The information was collected via questionnaire or telephone from 4,920 respondents across the United
States. The Westat Survey was rated as a high-quality study during data evaluation within the systematic
review process. The room of use selected for this evaluation is based on the room in which the Westat
Survey results reported the highest percentage of respondents that last used a product within the room.
When the Westat Survey identified the room of use where the highest percentage of respondents last used
the product as "other inside room", the utility room was selected within CEM for modeling. The pre-
defined product scenarios within CEM were selected based on a cross-walk to similar product categories
within the Westat Survey. A crosswalk between the 1-BP Consumer Use Scenarios and the corresponding
Westat product category selected to represent the exposure scenario is in Table-1-4.
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Table-1-4. Crosswalk Between 1-BP Consumer Use Scenarios and Westat Product Category
1-BP Consumer Use Scenario
Representative Westat Product Category
1. Adhesive Accelerant
Contact Cement, Super Glues, And Spray Adhesives
2. General Spray Cleaner
Solvent Type Cleaning Fluids Or Degreasers
3. Spot Cleaner-Stain Remover
Spot Removers
4. Mold Cleaning-Release Product
Solvent Type Cleaning Fluids Or Degreasers
5. General Cleaner-Degreaser
Engine Degreasers
6. Degreasers-Electronic
Specialized Electronics Cleaners (TV, VCR, Razor, Etc.)
7. Coin Cleaner/Scissors
Not Applicable
8. Automobile Ac Flush
Not Applicable
9. Insulation
Not Applicable
Additional key model input parameters were varied across both consumer use scenario and model
iterations. These key parameters were duration of use per event (minutes/use), amount of chemical in the
product (weight fraction), and mass of product used per event (gram(s)/use). Duration of use and mass of
product used per event values were both extracted from the Westat Survey (U.S. EPA. 1987). To allow
evaluation across a spectrum of use conditions, the EPA chose the Westat Survey results for these two
parameters from the above cross-walked product categories representing the tenth, fiftieth (median), and
ninety-fifth percentile data, as presented in the Westat Survey.
The amount of chemical in the product (weight fraction) was extracted from product specific SDS. This
value was varied across the given range of products within the same category to obtain three values, when
available. Unlike the Westat survey results which gave percentile data, however, product specific SDS
across products did not have percentile data so the values chosen represented the lowest weight fraction,
mean weight fraction (of the range available), and the highest weight fraction found. Even using this
approach, some SDS were only available for a single product with a single weight fraction or very small
range, or multiple products which only provided a single weight fraction or a very small range. For these
product scenarios, only a single weight fraction was used in CEM for modeling. Table 1-5 summarizes
the input parameter values used for these three parameters by consumer use.
Table 1-5 Model Input Parameters Varied by Consumer Use
Consumer Use
Duration of Use
Mass of Product Used
Amount of Chemical In
Product
(minutes/use)
(
gram(s)/use)
(weight fraction)
10th
50th
95th
10th
50th
95th
Low
Mean
High
Adhesive
Accelerant
0.5
4.25
60
1.20
9.98
172.45

0.99
(single)

General Spray
Cleaner
2
15
120
21.86
126.86
1249.04

0.94
(single)

Spot Cleaner/Stain
Remover
0.5
5
30
9.76
51.91
434.43
0.276
0.58
0.922
Mold
Cleaning/Release
0.5
2
30
3.84
21.14
192.21
0.32
0.6
0.915
General Cleaner-
Degreaser
5
15
120
111.86
445.92
1845.17
0.109
0.505
0.9505
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Consumer Use
Duration of Use
Mass of Product Used
Amount of Chemical In
Product
(minutes/use)
(
gram(s)/use)
(weight fraction)
10th
50th
95th
10th
50th
95th
Low
Mean
High
Degreaser-
Electronic
0.5
2
30
1.56
19.52
292.74
0.496
0.72
0.972
1.2.2 MCCEM Approach
Like CEM, MCCEM is peer reviewed and includes several distinct models appropriate for
evaluating specific product and article types and use scenarios. Two of the distinct models (M32
and M33) can evaluate emission rates due to evaporation from a liquid in a container (a "solvent
pool"). Model M32 applies to an evaporating solvent or solvent pool with a fixed surface area.
At a given temperature, the emission rate in this model is determined by (1) the gas-phase mass
transfer coefficient, (2) the vapor pressure, and (3) the back-pressure effect.
Model M33 was developed for sublimation of p-dichlorobenzene from moth cakes. However,
because sublimation and evaporation of pure compounds share similar mechanisms, M33 can
also be applied to emissions from solvent pools. At a given temperature, the emission rate in this
model is dependent on the gas-phase mass transfer coefficient, the saturation concentration for a
pure compound, and the prevailing indoor air concentration.
For both M32 and M33 models, the emission rate is governed by the source area and is not
dependent on chemical mass, provided the duration of use is less than the time it takes for all of
the chemical of concern to evaporate. Therefore, the emission rate determined using either model
is assumed to be constant and in-effect until all available mass of the chemical of concern is
evaporated.
MCCEM uses a two-zone representation of the building of use when predicting indoor air
concentrations similar to CEM. MCCEM also is capable of further division of Zone 1 into near
field and far field. Inhalation exposure is estimated in MCCEM based on zones and pre-defined
activity patterns again, similar to CEM.
Consumer uses 7 and 8 identified in Table 1-2 (coin/scissors cleaner and automobile AC flush,
respectively) were assessed for inhalation exposure using MCCEM. A general internet search
and investigation into coin cleaning revealed an expected use pattern is to place the coin cleaner
product into a small, open top dish or bowl. Coins to be cleaned are then placed within the pool
of product, soaked, scrubbed/wiped, and then removed for drying. A similar search and
investigation into automobile AC flush activities revealed an expected use pattern is to directly
spray the flush product into the opened automobile AC system, which is then transfered via
pressure through the system to the opposite end and flushed out into an open top bucket where it
is collected. Considering these expected use patterns, exposure to 1-BP within these products is
assessed as evaporation from a liquid in a container. The M33 model was utilized to evaluate
inhalation exposure for each consumer use evaluated with MCCEM and applied by assuming a
constant emission rate during the entire period when the source is active (product is used and
remains open to the use environment). Use of the M33 model for these scenarios causes the
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emission rate to be governed by the source area and not chemical mass (weight fraction and mass
of product used). Since the emission rate is not dependent on chemical mass for these two
scenarios, only duration of use was varied for the multiple iterations run. This results in three
exposure cases per consumer use modeled with MCCEM, rather than the maximum of 27
exposure cases for those modeled with CEM. Consistent with the CEM approach, U.S. EPA
evaluated utilized the near-field and far-field option for inhalation exposure.
CEM was used to evaluate dermal exposure from the coin and scissors cleaner and automobile
AC flush consumer use scenarios because MCCEM does not have a representative dermal model
for these two scenarios. The U.S. EPA utilized the permeability methodology and model (P-
DERlb) within CEM for dermal exposure.
1.2.2.1 MCCEM Inputs
The inputs needed for MCCEM include: (1) the emission rate; (2) product amount and duration
of use; (3) house and zone volumes; and (3) airflows to and from each zone. Like the CEM
modeling approach, the activity pattern was applied to the modeled concentrations during post-
processing to determine inhalation exposure concentrations. Detailed spreadsheets of all input
parameters used for each consumer use evaluated with MCCEM are provided in 1-BP Supplemental File:
Information on Consumer Exposure Assessment Model Input Parameters (EPA. 2019a).
1.2.2.1.1 Emission Rate
The emission rate when using the M33 model and assuming zero for the prevailing indoor air
concentration, as we did for these two scenarios, is the product of three quantities: (1) mass-
transfer coefficient; (2) saturation concentration; and (3) exposed surface area. To estimate the
mass-transfer coefficient, EPA used the program PARAMS, which involves the following
components:
Air Density, calculated at 23 C and 50% RH;
Viscosity of Air, calculated at 23 C;
Velocity, the midpoint of the recommended range of 5-10 cm/s;
Diffusivity in air, calculated using the Wilke Lee method; and
Characteristic length - PARAMS describes this parameter as follows: "Characteristic
length is often approximated by the square root of the source area."
The source area is used in estimating both the mass-transfer coefficient and the emission rate.
For the coin cleaner, EPA chose a small bowl as the product reservoir with a 4-inch diameter,
giving a source area of 81 cm2, a characteristic length of 9 cm, and an estimated mass-transfer
coefficient of 6.01 m/h. For the automobile AC flush, EPA chose a bucket as the flushed product
reservoir with a 12-inch diameter, giving a source area of 730 cm2, a characteristic length of 27.0
cm, and an estimated mass-transfer coefficient of 3.47 m/h.
The saturation concentration for 1-BP is 966,000 mg/m3 (966 g/m3). For the coin cleaner,
multiplication by the mass-transfer rate (6.01 m/h) and the source area (81 cm2 or 0.0081 m2)
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gives an emission rate of 47,026 mg/h (47 g/h). For the AC auto flush, multiplication by the
mass-transfer rate (3.47 m/h) and the source area (730 cm2 or 0.073 m2) gives an emission rate of
244,697 mg/h (244.7 g/h).
1.2.2.1.2	Product Amount and Duration of Use
As discussed above, the emission rate is governed by surface area of the solvent pool and not
chemical mass. Therefore, only duration of use is varied for inhalation exposure. Based on the
expected use conditions described above, and in an effort to characterize a potential range of
consumer inhalation exposures, the EPA chose three durations of use for the coin cleaner (15, 30,
and 60 minutes) and three durations of use for the automobile AC flush (5, 15, and 30 minutes).
While inhalation exposure for the coin cleaner consumer use is determined for 15, 30, and 60
minutes, we do not expect dermal contact to occur for the entire period of time the product is
being used. Coin cleaning is expected to be a somewhat passive activity where coins may remain
undisturbed within the pool for an extended period of time. As a result, dermal exposure will
occur for a shorter period of time when coins are placed into the product, potentially
scrubbed/wiped within the product, and taken out for drying. Outside of these activities, dermal
exposure is not expected to occur although the user remains within the room inhaling the vapors
expelled from the pool. For dermal exposure to coin cleaner product, we present the exposure
values representing the total exposure from use (cumulative which is beginning and end of use)
for 2 minutes, 4 minutes, and 6 minutes of ongoing dermal exposure.
Unlike coin cleaning, automobile AC flushing is an active process where material is constantly
sprayed into the system, flushed through, and exits the system. Inhalation exposure occurs for the
entire period of time and since it is an active process, dermal exposure can also occur for the
entire period of time. As a result, for inhalation and dermal exposure to the automobile AC flush,
we present the exposure values representing 5, 15, and 30 minutes of ongoing exposure.
1.2.2.1.3	Zone Definitions, Volumes, and Airflow Rates
The zone volumes and airflow rates for the coin cleaner consumer use are discussed below. For
this consumer use, EPA is assuming the zone of use to be the utility room, with a volume of 20
m3 that is further split into near-field and far-field zones for which the respective volumes (1 m3
and 19-m3) are consistent with CEM defaults. The assumed house volume is 446 m3, resulting in
a volume of 426 m3 for the third zone, termed the "rest of house" or ROH.
The air exchange rate for the house (0.45) is the same as the CEM default. The interzonal airflow
rate was 100 m3/h. EPA assumed there was no air flow between the near field and outdoors
(Zone 0). For the interzonal airflow rate between the utility room and ROH, the CEM default rate
of 107.1 m3/h was used.
For the auto AC flush scenario, EPA assumed the zone of use to be the garage with a volume of
118 m3. This volume is the average for 15 single-family homes with attached garages as reported
by Batterman et al. (Batterman et al.. 2007). The garage was further split into a 4-m3 near field
and a 114-m3 far field. Zone 3 was defined as the entire house volume of 446 m3, which did not
include the garage.
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The air exchange rate for the house (0.45) matches that used for the coin cleaner consumer use.
Relatively few measurements have been taken of garage air exchange rates. Emmerich et al.
(Emmerich et al.. 2003) used a blower door to measure the airtightness of garages under
induced-pressurization conditions for a limited sample of homes but with a range of house ages,
styles, and sizes. The average airtightness measured was 48 air changes per hour at 50 Pa
(ACH50). This is consistent with values used by energy engineers and technicians who have
performed such tests for many years, and corresponds to an air exchange rate of - 2.5 air
exchanges/h (giving an airflow rate of 295 m3/h ) under naturally occurring conditions. EPA also
assumed an airflow rate of 107.1 m3/h between the garage and house as well as an airflow rate of
zero between the near field and outdoors.
1.2.3 IECCU Approach
IECCU is a peer reviewed simulation program which can be used as (1) a general-purpose indoor
exposure model in buildings with multiple zones, multiple chemicals and multiple sources and
sinks or (2) as a special-purpose concentration model for simulating the effects of sources in
unconditioned zones on the indoor environmental concentrations in conditioned zones. IECCU
was developed by combining existing code and algorithms implemented in other EPA indoor
exposure models and by adding new components and methods.
The general mass balance equation used by IECCU to determine the change in the concentration
of a chemical of concern in air within a given zone is determined by six factors: (1) the emissions
from the sources in the zone, (2) the rate of chemical removed from the zone by the ventilation
and interzonal air flows, (3) the rate of chemical carried into the zone by the infiltration and
interzonal air flows, (4) the rate of chemical sorption by interior surfaces, (5) the rate of chemical
sorption by airborne particles, and (6) the rate of chemical sorption by settled dust. Since 1-BP is
highly volatile, once it is in the vapor phase it is expected to remain in the vapor phase. As a
result, the U.S. EPA only considered the first three factors listed above. Input parameters for the
IECCU model were obtained from the U.S. EPA's Exposure Factors Handbook, Literature, or
empirical and QSAR models.
The final consumer use identified in Table 1-2 (Insulation, off-gassing) was evaluated for inhalation
exposure using IECCU. Modeling efforts estimated the air concentration of 1-BP by conducting a series
of simulations for a ""typical" residential building by using existing mass transfer models and simulation
tools. Most parameters were either obtained from data in the literature or estimated with empirical and
QSAR models. The insulation source of 1-BP was Polyiso insulation boards.
A three-zone configuration described by Bevington et al. in Developing Consensus Standards for
Measuring Chemical Emissions from Spray Polyurethane Foam (SPF) insulation (Sebroski. 2017) was
used to represent a generic residential building, where the insulation is applied to both the attic and
crawlspace. The baseline ventilation and interzonal air flows are shown in Figure 1. The ventilation rates
for the three zones are shown in Table 1 -6. The EPA used the ventilation rates for the "vented" attic and
crawlspace in this evaluation.
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Qo2 = 300 m3/h (vented)
Qo2 = 105 m3/h (unvented)
Zone 2 (Attic)
V2 = 150 m3
t


^ Q2i = 15 m3/h (vented)
Q21 = 5 m3/h (unvented)

Qoj = 150 m3/h
supply air

Zone 1 (Living Space)
Vt = 300 m3
Qio

Qoj = 150 m1/

~ Q31 = 15 m3/h (vented)
Q31 = 5 m3/h (unvented)
h(vented)
1
Zone 3 (Crawlspace)
Qo3 = 52.5 m3
(unvented)
HVAC
Vj = 150 m3

	 return air	- jq m3/h (leakage to the return flow duct)
Figure 1 The three-zone configuration for a generic residential setting and baseline ventilation
and interzonal air flows.
Table 1-6. Zone Names, Volumes, and Baseline Ventilation Rates
Zone name
Zone volume (nv!)
Ventilation rate (h1)
Living space
300
0.5
Attic
150
2.0 (vented)
0.7 (unvented)
Crawlspace
150
1.0 (vented)
0.35 (unvented)
Unlike CEM and MCCEM, IECCU does not yet provide default values for input parameters. As
a result, model inputs are derived from empirical data or modeled estimates. It is the user's
responsibility to choose appropriate modeling inputs for the chemical and exposure scenario of
interest. A detailed spreadsheet of all input parameters used for the insulation consumer use evaluated
with IECCU for this evaluation is provided in 1-BP Supplemental File: Information on Consumer
Exposure Assessment Model Input Parameters (EPA. 2019a).
1.2.4 Consumer Exposure Results
All modeling results were exported into Excel workbooks for additional processing and
summarizing. All modeling outputs for each condition of use evaluated are included by condition
of use in 1-BP Supplemental File: Information on Consumer Exposure Assessment Model Outputs
(EPA. 2019b).
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Outputs from the models used for consumer exposure were in units of mg/m3. Health endpoints
were provided in parts per million (ppm), therefore the U.S. EPA converted units from mg/m3 to
ppm by multiplying the concentration output by the molar volume (24.45) and dividing by the
molecular weight of 1-BP (122.99 g/mol) using the following equation.
Concentration (ppm) = 24.45 X concentration (mg/m3)/MW
2 Model Sensitivity Analyses
Model sensitivity analyses conducted on the models used for this evaluation enable users to
identify what input parameters have a greater impact on the model results (either positive or
negative). This information was used for this evaluation to help justify the approaches used and
input parameters varied for our modeling.
2.1 CEM Sensitivity Analysis
The CEM developers conducted a detailed sensitivity analysis for CEM version 1.5, as described in
Appendix C of the CEM User Guide.
In brief, the analysis was conducted on non4inear, continuous variables and categorical variables that
were used in CEM models. A base run of different models using various product or article categories
along with CEM defaults was used. Individual variables were modified, one at a time, and the resulting
Chronic Average Daily Dose (CADD) and Acute Dose Rate (ADR) were then compared to the
corresponding results for the base run. Two chemicals were used in the analysis: bis(2-ethylhexyl)
phthalate was chosen for the SVOC Article model (emission model E6) and benzyl alcohol for other
models. These chemicals were selected because bis(2-ethylhexyl) phthalate is a SVOC, better modeled by
the Article model, and benzyl alcohol is a VOC, better modeled by other equations.
All model parameters were increased by 10% except those in the SVOC Article model (increased by
900% because a 10% change in model parameters resulted in very small differences). The measure of
sensitivity for continuous variables was elasticity, defined as the ratio of percent change in each result to
the corresponding percent change in model input. A positive elasticity means that an increase in the
model parameter resulted in an increase in the model output whereas a negative elasticity had an
associated decrease in the model output. For categorical variables such as receptor and room type, the
percent difference in model outputs for different category pairs was used as the measure of sensitivity.
The results are summarized below for inhalation vs. dermal exposure models and for categorical vs.
continuous user-defined variables.
Exposure Models
For the first five inhalation models (E1-E5) a negative elasticity was observed when increasing the use
environment, building size, air zone exchange rate, and interzone ventilation rate. All of these factors
decrease the chemical concentration, either by increasing the volume or by replacing the indoor air with
cleaner (outdoor) air. Increasing the weight fraction or amount of product used had a positive elasticity
because this change increases the amount of chemical added to the air, resulting in higher exposure.
Vapor pressure and molecular weight also tended to have positive elasticities.
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For most inhalation models, the saturation concentration did not have a notable effect on the ADR or the
CADD. Mass of product used and weight fraction both had a positive linear relationship with dose. All
negative parameters had elasticities less than 0.4, indicating that some terms (e.g., air exchange rates,
building volume) mitigated the full effect of dilution. That is, even though the concentration is lowered,
the effect of removal/dilution is not stronger than that of the chemical emission rate. Most models had an
increase in dose with increasing duration of use. Increasing this parameter typically increases the peak
concentration of the product, thus giving a higher overall exposure.
The results for the dermal model were different from the inhalation models, in that the elasticities for
CADD and ADR were nearly the same. This outcome is consistent with the model structure, in that the
chemical is placed on the skin so there is no time factor for a peak concentration to occur. The modeled
exposure is based on the ability of a chemical to penetrate the skin layer once contact occurs. Dermal
permeability had a near linear elasticity whereas log Kow and molecular weight had zero elasticities.
User-defined Variables
These variables were separated into categorical vs. continuous. For categorical variables there were
multiple parameters that affected other model inputs. For example, varying the room type changed the
ventilation rates, volume size and the amount of time per day that a person spent in the room. Thus, each
modeling result was calculated as the percent difference from the base run. For continuous variables, each
modeling result was calculated as elasticity.
Among the categorical variables, both inhalation and dermal model results had a positive change when
comparing an adult to a child and to a youth, with dermal having a smaller change between receptors than
inhalation and the largest difference occurring between an adult and a child for both models. The time of
day when the product was used and the duration of use occurred while the person was at home; thus, there
was no effect on the ADR because the acute exposure period was too short to be affected by work
schedule. Most rooms had a negative percent difference for inhalation, with the single exception of the
bedroom where the receptor spent a large amount of time with a smaller volume than the living room.
For dermal, the only room that resulted in a large percent difference was office/school, due to the fact that
the person spent only Vi hour at that location when the stay-at-home activity pattern was selected. For
inhalation, changing from a far field to a near field base resulted in a higher ADR and CADD, likely
because the near field has a smaller volume than that of the total room.
There are three input parameters for the near-field, far-field option for CEM product inhalation models.
To determine the sensitivity of model results to these inputs, CEM first was run in base scenario with the
near-field option, after which separate runs were performed whereby the near-field volume was increased
by 10%, the far-field volume was increased by 10%, and the air exchange rate was increased by 10%. For
inhalation, both the air exchange rate and volume had negative elasticities, but the air exchange rate had a
much higher elasticity (near one) than the volume (0.11).
3 References
Batterman, S; Jia, C; Hatzivasilis, G. (2007). Migration of volatile organic compounds from attached
garages to residences: A major exposure source. Environ Res 104: 224-240.
http://dx.doi.Org/10.1016/i.envres.2007.01.008
DHHS. (2017). Skin Notation (SK) Profile 1-Bromopropane. CDC.
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Emmerich. SJ; Gorfain, JE; Howard-Reed, C. (2003). Air and pollutant transport from attached garages to
residential living spaces - literature review and field tests. Int J Vent 2: 265-276.
EPA. US. (2019a). Draft Risk Evaluation for 1-Bromopropane - 1-BP Supplemental File: Information on
Consumer Exposure Assessment Model Input Parameters.
EPA. US. (2019b). Draft Risk Evaluation for 1-Bromopropane - 1-BP Supplemental File: Information on
Consumer Exposure Assessment Model Outputs.
Sebroski. JMM. (2017). Developing consensus standards for measuring chemical emissions from spray
polyurethane foam (SPF) insulation. Washington, DC: ASTM International.
http://dx.doi.org/10.1520/STP1589-EB
U.S. EPA. (2019). Multi-Chamber Concentration and Exposure Model (MCCEM) User Guide. U.S. EPA.
U.S. EPA. (1987). Household solvent products: A national usage survey. (EPA-OTS 560/5-87-005).
Washington, DC: Office of Toxic Substances, Office of Pesticides and Toxic Substances.
https://ntrl.ntis.gov/NTRL/dashboard/searchResults.xhtml?searchQuerv=PB88132881
U.S. EPA. (2011). Exposure factors handbook: 2011 edition (final) [EPA Report], (EPA/600/R-090/052F).
Washington, DC: U.S. Environmental Protection Agency, Office of Research and Development,
National Center for Environmental Assessment.
http://cfpub.epa.gov/ncea/cfm/recordisplay.cfm?deid=236252
U.S. EPA. (2019a). Consumer Exposure Model (CEM) 2.1 User Guide. (EPA Contract # EP-W-12-010).
Washington, DC.
U.S. EPA. (2019b). Consumer Exposure Model (CEM) 2.1 User Guide - Appendices. (EPA Contract # EP-W-
12-010). Washington, DC: U.S. EPA.
U.S. EPA. (2019c). IECCU 1.1 User's Guide. In Simulation Program for Estimating Chemical Emissions from
Sources and Related Changes to Indoor Environmental Concentrations in Buildings with
Conditioned and Unconditioned Zones (IECCU). (EPA Contract# EP-W-12-010). Washington, DC:
U.S. Environmental Protection Agency, Office of Pollution Prevention and Toxics.
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