PUBLIC RELEASE DRAFT
May 2025
EPA-740-D-25-015
May 2025
Office of Chemical Safety and
Pollution Prevention
xvEPA
United States
Environmental Protection Agency
Draft Consumer and Indoor Exposure Assessment for
Dibutyl Phthalate
(DBP)
Technical Support Document for the Draft Risk Evaluation
CASRN 84-74-2
CH,
H,C
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\_
May 2025
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TABLE OF CONTENTS
SUMMARY 6
1 INTRODUCTION 8
2 CONSUMER EXPOSURE APPROACH AND METHODOLOGY 10
2.1 Products and Articles with DBP Content 11
2.1.1 Solid Articles 12
2.1.2 Liquid, Paste, and Powder Products 16
2.2 Inhalation and Ingestion Modeling Approaches 22
2.2.1 Inhalation and Ingestion Modeling for Products 23
2.2.2 Inhalation and Ingestion Modeling for Articles 24
2.2.3 CEM Modeling Inputs and Parameterization 25
2.2.3.1 Key Parameters for Articles Modeled in CEM 27
2.2.3.2 Key Parameters for Liquid and Paste Products Modeled in CEM 32
2.3 Dermal Modeling Approach 36
2.3.1 Dermal Absorption Data 36
2.3.2 Flux-Limited Dermal Absorption for Liquids 37
2.3.3 Flux-Limited Dermal Absorption for Solids 38
2.3.4 Modeling Inputs and Parameterization 39
2.4 Key Parameters for Intermediate Exposures 43
2.5 Tire Crumb Rubber Modeling 44
2.5.1 Tire Crumb Inhalation Exposure 44
2.5.2 Tire Crumb Dermal Exposure 45
2.5.3 Tire Crumb Ingestion Exposure 45
2.5.4 Calculation of Acute and Chronic Doses 46
3 CONSUMER EXPOSURE MODELING RESULTS 47
3.1 Acute Dose Rate Results, Conclusions and Data Patterns 47
3.2 Intermediate Average Daily Dose Conclusions and Data Patterns 55
3.3 Non-Cancer Chronic Dose Results, Conclusions and Data Patterns 56
4 INDOOR DUST MODELING AND MONITORING COMPARISON 62
4.1 Indoor Dust Monitoring 62
4.2 Indoor Dust Monitoring Approach and Results 65
4.3 Indoor Dust Comparison Between Monitoring and Modeling Ingestion Exposure Estimates .. 67
5 WEIGHT OF SCIENTIFIC EVIDENCE 69
5.1 Consumer Exposure Analysis Weight of the Scientific Evidence 69
5.2 Indoor Dust Monitoring Weight of the Scientific Evidence 79
5.2.1 Assumptions in Estimating Intakes from Indoor Dust Monitoring 81
5.2.1.1 Assumptions for Monitored DBP Concentrations in Indoor Dust 81
5.2.1.2 Assumptions for Body Weights 82
5.2.1.3 Assumptions for Dust Ingestion Rates 82
5.2.2 Uncertainties in Estimating Intakes from Monitoring Data 83
5.2.2.1 Uncertainties for Monitored DBP Concentrations in Indoor Dust 83
5.2.2.2 Uncertainties for Body Weights 83
5.2.2.3 Uncertainties for Dust Ingestion Rates 84
5.2.2.4 Uncertainties in Interpretation of Monitored DBP Intake Estimates 84
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6 CONCLUSION AND STEPS TOWARD RISK CHARACTERIZATION 85
7 REFERENCES 86
Appendix A ACUTE, CHRONIC, AND INTERMEDIATE DOSE RATE EQUATIONS 92
A. 1 Acute Dose Rate 92
A,2 Non-Cancer Chronic Dose 96
A.3 Intermediate Average Daily Dose 99
A.4 Dermal Absorption Dose Modeling for Acute and Chronic Exposures 100
LIST OF TABLES
Table 1-1. Consumer Conditions of Use Table 9
Table 2-1. Summary of Consumer COUs, Exposure Scenarios, and Exposure Routes 18
Table 2-2. COUs and Products or Articles Without a Quantitative Assessment 22
Table 2-3. CEM 3.2 Model Codes and Descriptions 25
Table 2-4. Crosswalk of COU Subcategories, CEM 3.2 Scenarios, and Relevant CEM 3.2 Models
Used for Consumer Modeling 26
Table 2-5. Summary of Key Parameters for Inhalation and Dust Ingestion Exposure to DBP from
Articles Modeled in CEM 3.2 29
Table 2-6. Chemical Migration Rates Observed for DBP Under Mild, Medium, and Harsh Extraction
Conditions 31
Table 2-7. Mouthing Durations for Children for Toys and Other Objects 32
Table 2-8. Summary of Key Parameters for Products Modeled in CEM 3.2 35
Table 2-9. Key Parameters Used in Dermal Models 40
Table 2-10. Short-Term Event per Month and Day Inputs 44
Table 4-1. Detection and Quantification of DBP in House Dust from Various Studies 64
Table 4-2. Estimates of DBP Settled Dust Ingestion Per Day from Monitoring, Ages 0-21 Years 66
Table 4-3. Estimates of DBP Settled Dust Ingestion Per Day from Monitoring, Ages 21-80+ Years.... 66
Table 4-4. Comparison Between Modeled and Monitored Daily Dust Intake Estimates for DBP 67
Table 5-1. Weight of Scientific Evidence Summary Per Consumer COU 74
Table 5-2. Weight of the Scientific Evidence Conclusions for Indoor Dust Ingestion Exposure 79
Table 5-3. Summary of Variables from Ozkaynak et al. 2022 Dust/Soil Intake Model 82
Table 5-4. Comparison Between Ozkaynak et al. 2022 and Exposure Factors Handbook Dust
Ingestion Rates 84
LIST OF FIGURES
Figure 2-1. DBP Average Absorptive Flux vs. Absorption Time 39
Figure 3-1. Acute Dose Rate for DBP from Ingestion, Inhalation, and Dermal Exposure Routes in
Infants (<1 Year) and Toddlers (1-2 Years) 49
Figure 3-2. Acute Dose Rate of DBP from Ingestion, Inhalation, and Dermal Exposure Routes for
Preschoolers (3-5 Years) and Middle Childhood (6-10 Years) 50
Figure 3-3. Acute Dose Rate of DBP from Suspended and Settled Dust Ingestion and Mouthing for
Infants (<1 Year) 51
Figure 3-4. Acute Dose Rate of DBP from Suspended and Settled Dust Ingestion and Mouthing for
Preschoolers (3-5 Years) 51
Figure 3-5. Acute Dose Rate of DBP from Ingestion, Inhalation, and Dermal Exposure Routes for
Young Teens (11-15 Years) and for Teenagers and Young Adults (16-20 Years) 53
Figure 3-6. Acute Dose Rate of DBP from Ingestion, Inhalation, and Dermal Exposure Routes in
Adults (21+ Years) 54
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Figure 3-7. Acute Dose Rate of DBP from Suspended and Settled Dust Ingestion Exposure Routes
for Young Teens (11-15 Years), Teenagers and Young Adults (16-20 Years), and
Adults (21+ Years) 55
Figure 3-8. Intermediate Dose Rate for DBP from Inhalation Exposure Route in Infants (< Year) and
Toddlers (1-2 Years) 55
Figure 3-9. Intermediate Dose Rate for DBP from Inhalation Exposure Route in Preschoolers (3-5
Years) and Middle Childhood (6-10 Years) 56
Figure 3-10. Intermediate Dose Rate of DBP from Inhalation and Dermal Exposure Routes for Young
Teens (11-15 Years) and for Teenagers and Young Adults (16-20 Years) 56
Figure 3-11. Intermediate Dose Rate of DBP from Inhalation and Dermal Exposure Routes for Adults
(21+Years) 56
Figure 3-12. Chronic Dose Rate for DBP from Ingestion, Inhalation, and Dermal Exposure Routes in
Infants (<1 Year Old) and Toddlers (1-2 Years) 58
Figure 3-13. Chronic Dose Rate of DBP from Ingestion, Inhalation, and Dermal Exposure Routes for
Preschoolers (3-5 Years) and Middle Childhood (6-10 Years) 59
Figure 3-14. Chronic Dose Rate of DBP from Ingestion, Inhalation, and Dermal Exposure Routes for
Young Teens (11-15 Years) and for Teenagers and Young Adults (16-20 Years) 60
Figure 3-15. Chronic Dose Rate of DBP from Ingestion, Inhalation, and Dermal Exposure Routes in
Adults (21+ Years) 61
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KEY ABBREVIATIONS AND ACRONYMS
ADR
Acute dose rate
CADD
Chronic average daily dose
CASRN
Chemical Abstracts Service Registry Number
CDC
Centers for Disease Control and Prevention (U.S.)
CDR
Chemical Data Reporting
CEM
Consumer Exposure Model
CPSC
Consumer Product Safety Commission
CPSIA
Consumer Product Safety Improvement Act
COU
Condition of use
DBP
Dibutyl phthalate, Di-(2-ethylhexyl) phthalate
DIY
Do-it-yourself
EPA
Environmental Protection Agency (U.S.)
HPCDS
High Priority Chemicals Data System
MCCEM
Multi-Chamber Concentration and Exposure Model
OCSPP
Office of Chemical Safety and Pollution Prevention
OPPT
Office of Pollution Prevention and Toxics
PVC
Polyvinyl chloride
SDS
Safety data sheet
SVOC
Semi-volatile organic compound
TSCA
Toxic Substances Control Act
TSD
Technical support document
U.S.
United States
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SUMMARY
This technical support document (TSD) accompanies the TSCA Draft Risk Evaluation for Dibutyl
Phthalate (DBP') ( 025c). It provides detailed descriptions of DBP consumer uses and indoor
exposure assessments. DBP is a phthalate ester with Chemical Abstracts Service Registry Number
(CASRN) 84-74-2. DBP is primarily used as a plasticizer in consumer, commercial, and industrial
applications—though it is also used in adhesives, sealants, paints, coatings, rubbers, polyvinyl chloride
(PVC) plastics, and non-PVC plastics, as well as for other applications. It is added to make plastic soft
and flexible, like shower curtains, vinyl fabrics and textiles, and flooring. This draft assessment
considers human exposure to DBP in consumer products resulting from conditions of use (COUs) as
defined under the Toxic Substances Control Act (TSCA). The major routes of DBP exposure considered
were ingestion via mouthing, ingestion of suspended dust, ingestion of settled dust, inhalation, and
dermal exposure. The exposure durations considered were acute, intermediate, and chronic. Acute
exposures are for an exposure duration of 1 day, chronic exposures are for an exposure duration of 1
year, and intermediate exposures are for an exposure duration of 30 days.
For inhalation and ingestion exposures, EPA (or "the Agency") used the Consumer Exposure Model
(CEM) to estimate acute and chronic exposures to consumer users and bystanders. Intermediate
exposures were calculated from the CEM daily exposure outputs for applicable scenarios (U.S. EPA.
2025a) outside of CEM because the exposure duration for intermediate scenarios is outside the 60-day
modeling period CEM uses. For each scenario, high-, medium-, and low-intensity use exposure
scenarios were developed in which values for duration of use, frequency of use, and surface area were
determined based on reasonably available information and professional judgment (see Section 2.2 for
CEM parameterization and input selection). Overall, confidence in the estimates were robust or
moderate depending on product or article scenario (see Section 5.1). Briefly, CEM default scenarios
were selected for mass of product used, duration of use, and frequency of use. Generally, when using
CEM defaults EPA has robust confidence. When no CEM default was available or applicable for some
products, manufacturer instructions and online retailers provided details on recommended use of the
product; for example, mass of product used during product application (see Section 2.2.3.2).
Most inhalation and ingestion product use patterns overall confidence were robust because the
supporting evidence provided product-specific information. For articles, key parameters that control
DBP emission rates from articles in CEM models are weight fraction of DBP in the material, density of
article material, article surface area, and surface layer thickness. For articles that do not have default
CEM inputs, EPA's Exposure Factors Handbook or professional judgment was used to select the
duration of use and article surface area for the low, medium, and high exposure scenario levels for most
articles. The overall confidence for most inhalation and ingestion article use patterns was rated robust
because (1) the source of the information was the Handbook, or (2) when using professional judgment
the Agency based selection of inputs on online article descriptions for article surface area (see Section
2.2.3.1). EPA has a moderate confidence in ingestion via mouthing estimates due to uncertainties about
professional judgment inputs regarding mouthing durations for adult toys and synthetic leather furniture
for children. In addition, the chemical migration rate input parameter has a moderate confidence due to
the large variability in the empirical data used in this assessment and unknown correlation between
chemical migration rate and DBP concentration in articles.
Dermal exposures for both liquid products and solid articles were calculated outside of CEM; see the
Draft Consumer Exposure Analysis for Dibutyl Phthalate (DBP) (U. 2025a) for calculations and
inputs. CEM dermal modeling assumes infinite DBP migration from product to skin without considering
saturation, which result in overestimations of dose and subsequent risk (see Section 2.3 for a detailed
explanation). Low-, medium-, and high-intensity use exposure scenarios were developed for each
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product and article scenario by varying values for duration of dermal contact and area of exposed skin.
Confidence in the dermal exposure estimates were moderate depending on uncertainties associated with
input parameters. The flux-limited screening dermal absorption approaches for liquid and solid products
and articles assumes an excess of DBP in contact with the skin independent of DBP concentration in the
article/product. The flux-limited screening approach provides an upper-bound of dermal absorption of
DBP and likely results in some overestimations; see Section 5.1 for detailed discussion on limitations,
strengths, and confidence in dermal estimates. Briefly, inputs for duration of dermal contact were either
from the Exposure Factors Handbook or professional judgment based on product and article
manufacturer use descriptions. For products, manufacturer instructions provide details on recommended
use of the product (e.g., adhesives and sealants). However, for articles, typically such data is not
available from manufactures. Sometimes inputs can be found in the Handbook (e.g., vinyl flooring
contact duration), other times professional judgment is used (e.g., length of time an individual spends
sitting on a couch per day for medium-and low-intensity use scenarios).
For young teens, teenagers and young adults aged 11 to 20 years old as well as adults (21+ years),
dermal contact was a strong driver of exposure to DBP, with the dose received being generally higher
than or similar to the dose received from exposure via inhalation or ingestion. The largest acute dose
estimated was for dermal exposure to adhesives, sealers, coatings, and waxes for young teens to adults.
The largest chronic dose estimated was for dermal and inhalation exposure to metal coatings for young
teens to adults, followed by dermal exposure to adhesives, footwear, and waxes. It is noteworthy that the
dermal screening analysis used a flux-limited approach, which has larger uncertainties than inhalation
dose results; see Section 5.1 for a detailed discussion of uncertainties within approaches, inputs, and
overall estimate confidence.
Among the younger lifestages, infant to 10 years, the pattern was less clear as these ages were not
designated as product users and therefore not modeled for dermal contact with any of the liquid products
assessed that resulted in larger dermal doses for the older lifestages. Key differences in exposures among
lifestages include (1) designation as a product user or bystander; (2) behavioral differences such as hand
to mouth contact times and time spent on the floor; and (3) dermal contact expected from touching
specific articles that may not be appropriate for some lifestages.
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1 INTRODUCTION
DBP is a phthalate ester (CASRN 84-74-2) and properties used to support product flexibility and
softness. DBP is primarily used as a plasticizer in consumer, commercial, and industrial applications
such as adhesives, sealants, paints, coatings, rubbers, PVC plastics, and non-PVC plastics as well as for
other applications. Some consumer DBP-containing solid article examples are car mats, synthetic leather
clothing, footwear, furniture components and textiles, vinyl flooring, wallpaper, shower curtains and
children's toys; liquid products including adhesives, sealants, and paints; and coatings for metal and
wood building materials. Under the Consumer Product Safety Improvement Act (CPSIA) of 2008
(CPSIA section 108(a), 15 U.S.C. § 2057c(a); 16 C.F.R. § 1307.3(a)), Congress permanently prohibited
the sale of children's toys or childcare articles containing concentrations of more than 0.1 percent DBP.
However, it is possible that some individuals may still have children's toys in the home that were
produced before statutory and regulatory limitations. EPA assembled reasonably available information
from 2016 and 2020 data reported in the Chemical Data Reporting (CDR) database and consulted a
variety of other sources, including published literature, company websites, and government and
commercial trade databases to identify products and articles under the defined COUs of DBP for
inclusion in the risk evaluation, see Table 1-1 for consumer-specific COUs. Consumer products and
articles were identified and matched to COUs. Weight fractions of DBP in specific items were then
gathered from a variety of sources, such as safety data sheets (SDSs), databases, and peer-reviewed
publications. These data were used in this assessment in a tiered approach as described in Section 2.1.
The migration of DBP from consumer products and articles has been identified as a potential mechanism
of exposure. However, the relative contribution of various consumer goods to overall exposure to DBP
has not been well characterized. The identified uses can result in exposures to consumers and bystanders
(non-product users that are incidentally exposed to the product). For all the DBP containing consumer
products identified, the approach involves addressing the inherent uncertainties by modeling high-,
medium-, and low-intensity use exposure scenarios. Due to the lack of comprehensive data on various
parameters and the expected variability in exposure pathways, EPA used conservative screening
approaches to obtain exposure doses associated with DBP across COUs and various age groups.
Because PVC products are ubiquitous in modern indoor environments, and since DBP can leach,
migrate, or evaporate (to a lesser extent based on physical and chemical properties) into indoor air and
concentrate in household dust. Exposure to compounds through dust ingestion, dust inhalation, and
dermal absorption is a particular concern for young children between the ages of 6 months and 2 years.
This is because they crawl on the ground and pull up on ledges, which increases hand-to-dust contact,
and place their hands and objects in their mouths. Therefore, estimated exposures were assessed and
compared for children below and above 2 years of age.
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Table 1-1. Consumer Conditions of 1
Jse Table
Life-Cycle
Stage"
Category b
Subcategory'
Reference(s)
Automotive, fuel, agriculture,
outdoor use products
Automotive care products
(U.S. EPA. 2020a)
Adhesives and sealants
(MEMA. 2019; U.S. EPA. 2019b)
Construction, paint,
electrical, and metal products
Paints and coatings
(NLM. 2024; U.S. EPA. 2020a.
2019b; GoodGuide. 2011;
Streitberaer et al. 2011)
Fabric, textile, and leather products
(WSDE. 2023; U.S. EPA. 2020c.
2019b)
Furnishing, cleaning,
treatment care products
Floor coverings; construction and
building materials covering large
surface areas including stone, plaster,
cement, glass and ceramic articles;
fabrics, textiles, and apparel
(U.S. EPA. 2020a. 2019b)
Consumer
Cleaning and furnishing care
products
(NLM. 2024; U.S. EPA. 2019b;
GoodGuide. 2011)
Ink, toner, and colorant products
(i i r \ mi%)
Packaging, paper, plastic,
hobby products
Packaging (excluding food
packaging), including rubber articles;
plastic articles (hard); plastic articles
(soft); other articles with routine
direct contact during normal use,
including rubber articles; plastic
articles (hard)
(NLM. 2024; U.S. EPA. 2019b)
Toys, playground and sporting
equipment
(U.S. EPA. 2019a. c)
Automotive articles
(MEMA. 2019)
Other uses
Chemiluminescent light sticks
(U.S. EPA. 2020b)
Lubricants and lubricant additives
(MEMA. 2019)
Novelty articles
(Sipe et al., 2023; Stabile, 2013)
Disposal
Disposal
Disposal
(U.S. EPA. 2019b)
" Life Cycle Stage Use Definition (40 CFR 711.3) for "Consumer use" means the use of a chemical or a mixture containing
a chemical (including as part of an article, such as furniture or clothing) when sold to or made available to consumers for
their use.
b These categories of conditions of use appear in the Life Cycle Diagram, reflect CDR codes, and broadly represent
conditions of use of DBP in industrial and/or commercial settings.
c These subcategories represent more specific activities within the life cycle stage and category of the COUs of DBP.
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2 CONSUMER EXPOSURE APPROACH AND METHODOLOGY
The main steps in performing a consumer exposure assessment are summarized below:
1. Identification and mapping of product and article examples following the consumer COU table
(Table 1-1), product and article identification.
2. Compilation of manufacturer use instructions for products and articles to determine patterns of
use.
3. Selection of exposure routes and exposed populations according to product/article use
descriptions.
4. Identification of data gaps and further search to fill gaps with studies, chemical surrogates or
product and article proxies, or professional judgment.
5. Selection of appropriate modeling tools based on available information and chemical properties.
6. Gathering of input parameters per exposure scenario.
7. Parameterization of selected modeling tools.
Consumer products or articles containing DBP were matched with TSCA COUs appropriate for the
anticipated use of the item. Table 2-1 summarizes the consumer exposure scenarios by COU for each
product example(s), the relevant exposure routes, an indication of scenarios also used in the indoor dust
assessment, and whether the analysis was done qualitatively or quantitatively. The indoor dust
assessment uses consumer product information for selected articles with the goal of recreating the indoor
environment. The consumer articles included in the indoor dust assessment were selected for their
potential to have large surface area for dust collection.
A quantitative analysis was conducted when the exposure route was deemed relevant based on product
or article use description and there was sufficient data to parameterize the model. The qualitative
analysis is a discussion of exposure potential based on physical and chemical properties, and/or
available monitoring data, if available. When a quantitative analysis was conducted, exposure from the
consumer COUs was estimated by modeling. Each product or article was individually assessed to
determine whether all or some exposure routes were applicable, and approaches were developed
accordingly.
Exposure via inhalation and ingestion routes were modeled using EPA's CEM Version 3.2 (U.S. EPA.
2023). All exposure estimates for tire crumb rubber were calculated using a computational framework
implemented within a spreadsheet as described in Section 2.4 because CEM does not have capabilities to
model exposure to chemicals in particulate matter other than indoor dust. Dermal exposure to DBP-
containing consumer products was estimated using a computational framework implemented within a
spreadsheet. Refer to Dermal Modeling Approach in Section 2.3 for a detailed description of dermal
approaches, rationale for analyses conducted outside CEM, and consumer specific dermal parameters
and assumptions for exposure estimates. For each exposure route, EPA used the 10th percentile, average,
and 95th percentile value of an input parameter (e.g., weight fraction, surface area, etc.) to characterize
low, medium, and high exposure, where possible and according to condition of use. If only a range was
reported, EPA used the minimum and maximum of the range as the low and high values, with the
average of the minimum and maximum used for the medium scenario. See Section 2.1 for details about
the identified weight fraction data and statistics used in the low, medium, and high exposure scenarios.
All CEM and dermal spreadsheet calculations inputs, sources of information, assumptions, and exposure
scenario descriptions are available in the Draft Risk Evaluation for Dibutyl Phthalate (DBP) -
Supplemental Information File: Consumer Exposure Analysis ( E5a). High-, medium-, and
low-intensity use exposure scenarios serve as a two-pronged approach. First, it provides a sensitivity
analysis with insight on the impact of the main modeling input parameters (e.g., skin contact area,
duration of contact, frequency of contact) in the doses and risk estimates. And second, the high-intensity
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use exposure scenarios are used first to screen for potential risks at the upper-bound of possible
exposures, and to refine if needed.
Based on reasonably available information from the systematic review on consumer COUs and indoor
dust studies, inhalation of DBP is possible through DBP emitted from products and articles and DBP
sorbed to indoor dust and particulate matter. A detailed discussion of indoor dust references, sources,
and concentrations is available in Section 4. Due to DBP's low volatility, 1.81 xl0~6 atmm3/mol at 25
°C, there is expected to be negligible or very small gas-phase inhalation exposures. However, DBP's
physical and chemical properties—such as low vapor pressure, low solubility, and high Koa—suggest a
high affinity for organic matter that is typically present in household dust. See Draft Physical Chemistry
and Fate and Transport Assessment for Dibutyl Phthalate (DBP) TSD (U.S. EPA. 2024a) for further
description of physical chemical properties. The likelihood of sorption to suspended and settled dust is
supported by indoor monitoring data. Section 4.2 reports concentrations of DBP in settled dust from
indoor environments. Due to the presence of DBP in indoor dust, inhalation and ingestion of suspended
dust, and ingestion of settled dust, are both considered as exposure routes in this consumer assessment.
Oral exposure to DBP is also possible through incidental ingestion during product use, transfer of
chemical from hand-to-mouth, or mouthing of articles. Dermal exposure may occur via direct contact
with liquid products and solid articles during use. Based on these potential sources and pathways of
exposures that may result from the conditions of use identified for DBP, oral and dermal exposures to
consumers were assessed.
Qualitative analyses describing low exposure potential are discussed in Section 2.1 and mainly based on
physical and chemical properties or product and article use descriptions. For example, given the low
volatility of DBP, emissions to air from solid articles are expected to be relatively low. As such, articles
with a small surface area (less than ~1 m2) and articles used outdoors were not assessed for inhalation
exposure. For items with small surface area for emissions and dust collection, the potential for emission
to air and dust is further reduced. To verify this assumption, a CEM test run for a generic 1 m2 item with
30 percent DBP content by weight was performed. The combined doses from inhalation and dust
ingestion were four orders of magnitude less than the point of departure (POD) used to assess human
health risk in this draft assessment and are likely to be negligeable as compared to potential exposure by
dermal and mouthing routes, which were assessed as appropriate, see Draft DBP Risk Evaluation for
Dibutyl Phthalate (U.S. EPA. 2025c). Similarly, solid articles not expected to be mouthed (e.g., building
materials, outdoor furniture, etc.) were not assessed for mouthing exposure. Furthermore, because DBP
is a low volatility solid that is used primarily as a plasticizer in manufacturing, potential take-home
exposures are likely small in comparison to the exposures from scenarios considered in this assessment.
Thus, take-home exposures were not further explored.
EPA assessed acute, chronic, and intermediate exposures to DBP from consumer COUs. For the acute
dose rate calculations, an averaging time of 1 day is used to represent the maximum time-integrated dose
over a 24-hour period in which the exposure event occurs. The chronic dose rate is calculated iteratively
at a 30-second interval during the first 24 hours and every hour after that for 60 days and averaged over
1 year. Professional judgment and product use descriptions were used to estimate number of events per
day and per month for each product, for use in the calculation of the intermediate dose. Whenever
professional judgment was used, EPA provided a rationale and description of selected parameters.
2.1 Products and Articles with DBP Content
The preferred data sources for DBP content in U.S. consumer goods were safety data sheets (SDSs) for
specific products or articles with reported DBP content, peer-reviewed literature providing
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measurements of DBP in consumer goods purchased in the United States, and government reports
originating in the United States with manufacturer-reported concentrations. In instances where these
data from preferred sources were not available, DBP contents in specific products and articles provided
in peer-reviewed literature and government reports originating from Canada and the European Union
were used. Because manufacturing practices and regulations for DBP in consumer goods are comparable
between these regions and the United States, it is reasonable to assume that similarly formulated
products may be available across these regions. DBP weight fractions reported in the CDR database
were not used as they may pertain to a finished good in the product category reported, or it could
represent a chemical additive that will be added to other components during the manufacturing process
of the finished good.
EPA further evaluated the products and articles identified to ensure that data was representative of items
that may expose U.S. consumers to DBP. Where possible, SDSs were cross-checked with company
websites to ensure that each product could reasonably be purchased by consumers. In instances where a
product or article could not be purchased by a consumer, EPA did not evaluate the item in a do-it-
yourself (DIY) or application scenario but did determine whether consumers might reasonably be
exposed to the specific item as part of a purchased good, including homes and automobiles. For data
reported in literature and government reports, recent regulations for DBP content in specific items was
considered when determining whether data was likely to be relevant to the current U.S. consumer
market. For solid articles with enacted limits on DBP content (e.g., children's toys, childcare items), it
was considered reasonable that consumers might be exposed to older items with DBP content higher
than current limits via secondhand purchases or long-term use. For these items, exposures from new and
legacy toys were considered separately.
In addition to DBP weight fractions, EPA obtained additional information about physical characteristics
and potential uses of specific products and articles from technical specifications, manufacturer websites,
and vendor websites. These data were used in the assessment to define exposure scenarios. The
following section provides a summary of specific products and articles with DBP content identified for
each item, and Table 2-1 provides a summary of TSCA COUs determined for each item and exposure
pathways modeled.
2.1.1 Solid Articles
While DBP is known to be used in a large variety of solid articles, weight fraction data for solid articles
sold in the United States were limited. Consumer product data were obtained from the Washington State
Department of Ecology Consumer Product Monitoring Database (WSDB. 2023). which includes
children's items. Additionally, some information was obtained from the High Priority Chemicals Data
System (HPCDS, (WSDE. 2020)). a database compiling manufacturer reporting requirements from 2017
to 2024 per Washington and Oregon safe children's product regulations. However, HPCDS does not
identify specific products or articles, only generic categories (e.g., toys/games). DBP reporting in
HPCDS dates from 2017 to 2024.
As data for DBP content in solid items not specific to children were lacking for U.S. consumer goods, a
large amount of data was taken from monitoring studies of phthalates in consumer goods carried out in
European countries, and these values are assumed to be similar to contents in comparable items sold in
the U.S. In particular, a large amount of data was available for phthalates in consumer goods published
across several studies carried out by the Danish EPA. For articles that did not have U.S. data, it is
unclear if DBP is not present in U.S.-sold items or if these materials are not captured in U.S. monitoring
efforts. As such, EPA assessed these items under the assumption that the weight fractions reported by
the Danish EPA are representative of DBP content that could be present in items sold in the U.S.
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Given the high molecular weight (278.35 g/mol) and low vapor pressure (2.01 x 10-5 mmHg) of DBP,
partitioning into air and overlying dust from solid articles is expected to be limited. See Draft Physical
Chemistry and Fate and Transport Assessment for Dibutyl Phthalate (DBP) TSD ( 024a) for
further description of physical chemical properties. Consequently, inhalation and dust ingestion
exposure for items with small surface area of emissions (<1 m2, for example a kitchen counter or single
cushion chair) or those items used outdoors are expected to be insignificant as compared to exposure by
mouthing and dermal contact. As such, inhalation and dust ingestion were not assessed for these items.
For articles assessed for mouthing and/or dermal contact the weight fraction data is used to confirm the
presence of DBP in the article but these data are not used in the dermal and mouthing modeling, see
Sections 2.2.3.1 (mouthing) and 2.3 (dermal). Furthermore, dermal, and mouthing exposure assessments
include high-, medium-, and low-intensity use scenarios for each article using a range of modeling input
parameters described in the corresponding sections, such as dermal absorption-related parameters and
chemical migration rates (mouthing).
Adult Toys
Adult toys, also known as intimacy and sex toys, are objects that people use to increase or facilitate
sexual pleasure. Examples of adult toys include vibrators, dildos, sleeves, etc. These articles were
assessed for DBP exposure by mouthing and dermal routes. Vaginal and anal exposures were not
assessed due to a lack of use patterns information and modeling tools to calculate exposure for articles
with vaginal and anal use needed to complete a risk assessment. DBP was reported at 1.06x10 5 w/w in
an adult toy sample purchased in the United States (Sipe et at.. 2023).
Car Mats
Car floor mats were assessed for DBP exposure by inhalation, dust ingestion, and dermal pathways. The
only available data for DBP content in car mats was one car mat set purchased from an internet vendor
in Denmark, with reported DBP weight fraction of 1,4><10~4 w/w (Danish EPA. 2020). As data specific
to the U.S. market are lacking, this weight fraction value was used in the low, medium, and high
exposure scenarios.
Children's Toys
Children's toys were assessed for DBP exposure by inhalation, dust ingestion, dermal and mouthing
routes of exposure. Under the Consumer Product Safety Improvement Act (CPSIA) of 2008 (CPSIA
section 108(a), 15 U.S.C. § 2057c(a); 16 C.F.R. § 1307.3(a)), Congress permanently prohibited the sale
of children's toys or childcare articles containing concentrations of more than 0.1 percent DBP.
However, it is possible that some individuals may still have children's toys in the home that were
produced before statutory and regulatory limitations. A recent survey by the Danish EPA of PVC
products purchased from foreign online retailers found that DBP content in a toy bath duck of 1.7
percent exceeded the current Danish regulatory limit of 0.1 percent DBP (Danish EPA. 2020).
In the U.S. market, among the data for children's items from the Washington State database (WSDE.
2023). three toys had detectable concentrations of DBP; however, none toys had DBP content above the
statutory and regulatory limit of 0.1 percent ( 23). The HPCDS database contained data for
DBP measurements in 96 toy/game items with reporting dates from 2017 to 2024. Although there is
some uncertainty about the materials these items are manufactured from, based on the limited
descriptions in the database, EPA determined that these items are likely composed primarily of plastic
and rubber components. For example, some of the descriptions provided for toys were dolls, puppets,
action figures, board games, toy vehicles, soft toys, and more specific descriptions were toy soldiers,
glow in the dark plastic bugs, waterproof pouches, pink plastic recorder, yellow bendy man. DBP
content was reported to be <100 ppm (<0.0001 w/w) in 42 items, 100 to 500 ppm (0.0001-0.0005 w/w)
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in 44 items, 500 to 1,000 ppm (0.0005-0.001 w/w) in 9 items, and 5,000 to 10,000 ppm (0.005-0.01
w/w) in one item. This last item with DBP content over the statutory and regulatory limit of 0.1 percent
was listed as a non-ride toy vehicle fWSDE. 2020).
EPA assessed exposure to DBP in children's toys under two scenarios. In the first exposure scenario,
new toys produced for the U.S. market are assumed to comply with statutory and regulatory limits and
were therefore assessed with DBP weight fractions of 0.001 w/w in low, medium, and high exposure
scenarios. In the second scenario, legacy toys are assessed with weight fractions reported in the HPCDS
database, (WSDE. 2020). that are above the statutory and regulatory limit of 0.001 w/w. Based on the
reported data, the weight fractions of DBP used in low, medium, and high exposure scenarios were
0.005 w/w, 0.0075 w/w, and 0.01 w/w. One new toy in the HPCDS database tested 8 or more years after
the CPSIA had components with DBP content above the statutory and regulatory limit of 0.01 percent
(WSDE. 2020). The legacy toys scenario is more representative of any new toys with weight fractions
above the CPSIA statutory and regulatory limit.
Clothing
Clothing was assessed for DBP exposure by dermal contact only, but a different approach was taken for
adults and children based on anticipated contact with specific garments. DBP content was reported in
components of two adult sized garments by the Danish EPA. This included measurements of 0.00087
w/w in the outer layer of a raincoat (Dam )20) and 0.0012 w/w in a jacket reflector (Danish
D9). DBP has also been reported in synthetic leather materials sampled from furniture items (see
coated textiles description below). It is reasonable to assume that these materials may be used in
synthetic leather clothing as well, which is expected to have a greater potential for dermal exposure as it
may be worn more often than raincoats, has direct dermal contact, and may have a larger area of dermal
contact. As such, synthetic leather clothing was chosen as the representative clothing item for modeling
dermal exposure to DBP in adults and teens. Based on this data, the weight fraction of DBP is used to
confirm DBP in article and identified data range from 2x 10~6 to 7.2/10 4 w/w.
In the U.S. market, the Washington State database reported measurable DBP content in the outside
facing print, not in direct dermal contact, of four children's garments and in the exterior component of a
hat/mitten set. The DBP concentrations in these items ranged from 5.3x 10 6 to 1.30xl0~4w/w (WSDE.
2020). Given the low concentrations of DBP and limited dermal contact arising from its use on the
outside layer of clothing, DBP exposure from these, or similar items is not expected to be significant. In
addition, infants and children are not anticipated to wear synthetic leather clothing. As such, dermal
exposure to DBP from clothing was not modeled explicitly for infants and children; however, the
potential for dermal contact with these items is captured under the scenario "PVC articles with the
potential for semi-routine dermal exposure" outlined below.
Coated Textiles
Coated textiles were assessed for DBP exposure via inhalation, dust ingestion, mouthing, and dermal
uptake. The Danish EPA reported DBP measurements of 2x 10~6 to 7.2/ 10 4 w/w in 11 synthetic leather
furniture samples (Dani ). Synthetic leather is expected to have many potential
applications, including furniture, clothing, and accessory items such as belts and handbags. Exposure to
coated textiles was assessed as two representative articles expected to capture the highest exposure by
inhalation, dermal uptake, and ingestion due to large surface area of emissions and long dermal contact
times. To that end, consumer exposure to DBP from coated textiles was modeled in scenarios for
furniture and adult clothing. The low, medium, and high exposure scenarios for BBP in synthetic leather
used the minimum, average, and maximum reported weight fractions of 2xl0~6, 1.5/10 4, and 7,2/ 10 4
w/w, respectively.
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Footwear
Footwear components were assessed for DBP exposure by dermal contact only. DBP content was
reported by the Danish EPA in two footwear items including one flip-flop sandal at 0.297 w/w (Danish
i \ J020) and one rubber clog at 0.026 w/w (DanHi «I1 \ J009). In the U.S. market, DBP was
reported in the Washington State database at 2.Ixl0~5 w/w in one flip-flop sandal (WSDE. 2020). Based
on the reported data, the weight fractions of DBP used to confirm presence of DBP in article and range
of identified data from 0.26 to 0.3 w/w.
PVC Articles with Potential for Semi-Routine Dermal Exposure
DBP has been measured in a variety of consumer goods that are not expected to (1) be mouthed, (2) to
result in significant inhalation exposure due to their small size and/or outdoor only use, (3) result in
significant dermal exposures due to short and/or infrequent dermal contact events. However, EPA
recognizes that while dermal uptake of DBP from contact with these individual items is not expected to
be significant, given the widespread nature of the items, an individual could have significant daily
contact with some combination of these items and/or with other similar items that have not been
measured during monitoring campaigns. As such, these items have been grouped together for modeling
but represent a variety of TSCA COUs. It is likely that real world exposures to these types of items
would occur as a result of dermal contact with articles belonging to multiple COUs. However, the
contribution of individual COUs to exposure from these types of items is expected to vary at an
individual level due to differences in lifestyle and habits. As such, while this scenario encompasses
items from more than one COU, it may be viewed as an upper boundary for exposure to any of the
COUs included. Weight fractions of DBP are not used in dermal exposure calculations, they are
provided below only to demonstrate the broad range of the product types, formulations, and DBP
content, which may be captured in this model scenario.
In the U.S. market from the Washington State database, (WSDE. 20201 arts and crafts items including
pencil cases, stickers, vinyl liner, and a Halloween kit were identified with DBP content ranging from
5.4 10 6 to 2.1 xl0~4 w/w. Additionally, 1 bib contained DBP content of 1.19xl0~5 w/w, 1 light-up
jewelry item contained DBP content of 2.5 10 5 w/w, 20 packaging products contained DBP content
from 9><10~6 to 0.002 w/w, and 4 bag/pouch articles contained DBP content from 6.1 x 10~6 to 2xl0~4
w/w (WSDE. 2020). Additionally in the U.S. market from a 2012 study on consumer products, one
dryer sheet was identified with DBP content of 0.001 w/w (Podsom et at.. 2012).
In two studies, the Danish EPA reported measurable DBP content in several articles. Two hobby cutting
board samples had reported DBP of 0.0032 w/w, one chew toy for pets had reported DBP of 6.0xl0~5
w/w, two tape samples had reported DBP of 0.068 w/w and 0.072 w/w, one garden house had reported
DBP of 0.052 w/w, one glove had reported DBP of 2xl0~5 w/w, one football had a reported DBP of
3 x 10~5 w/w (Danish EPA. 2020). and one balance ball had reported DBP of 2.5 10 5 w/w (Ornish EPA.
2011).
Chemiluminescent light sticks, commonly called "glow sticks," consist of a chemical solution within a
plastic tube or other container. The Danish EPA reported DBP in two glow stick samples at 0.078 and
0.45 w/w (Dani? ). Glow sticks may be used during entertainment and play; within military
and police operations; and for recreational activities such as diving, fishing, and camping. It is unclear
from the provided data if DBP is present as part of the chemical solution or as part of the flexible plastic
tube. Exposure to DBP in the liquid component of glow sticks is expected to occur rarely after
accidental or intentional misuse of the item that results in breaking the outer casing and releasing the
interior liquid. Depending upon use patterns, dermal contact with the exterior housing occurs but is still
not expected to occur on a routine basis.
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Shower Curtains
Shower curtains were assessed for DBP exposure by inhalation, dust ingestion, and dermal exposure
routes. The Danish EPA reported DBP in one shower curtain sample at 6.3 x 10~5 w/w (Darn
2011). This weight fraction was applied for low, medium, and high exposure scenarios.
Vinyl Flooring
Vinyl flooring was assessed for DBP exposure by inhalation, dust ingestion, and dermal exposure. DBP
content was reported by the Danish EPA in vinyl coverings at 1.3 x 10~4 w/w (Danish EPA. ^ ). This
weight fraction was applied for low, medium, and high exposure scenarios.
Wallpaper
Wallpaper was assessed for DBP exposure by inhalation, dust ingestion, and dermal exposure routes.
DBP was reported by the Danish EPA for three wallpaper samples (Danish EPA. 2011). The minimum,
mean, and maximum weight fractions of DBP were 9.0xl0~6, 1.7x10~5, and 3.0xl0~5 w/w; these values
were used in low, medium, and high exposure scenarios.
2.1.2 Liquid, Paste, and Powder Products
Consumable products with DBP content were largely identified by manufacturer safety data sheets
(SDSs). Products with similar DBP content and expected use patterns were grouped together for
modeling as described below. Some products were not assessed for inhalation exposure due to the small
volume of the product that is expected to be used, short durations of use and thus a shorter duration for
emissions to air to occur (e.g., adhesives with short working times [less than a few minutes] until
solidification and liquids poured directly into a reservoir that is capped after product addition), and/or
products used in outdoor conditions where air exchange rates are high and product application are not
expected to generate aerosols. Note that for liquid and paste products assessed only for dermal exposure,
DBP content is provided here for context only as it is not used directly in exposure calculations for these
routes (see Sections 2.3.2 and 2.3.3 for details).
Adhesives and Sealants
One all-purpose adhesive used for small repairs was identified with DBP content. The reported DBP
content was less than 3 percent (Waim art. 2019). and this weight fraction of 0.03 w/w was used to
confirm DBP presence in product. Because small volumes of this adhesive are expected to be used and
the working time is short (<5 minutes), this product was evaluated for dermal exposure only.
One metal bonding adhesive used for small to moderately sized automotive repairs was identified with
DBP content of 1 to less than 3 percent (Ford Motor Company. 2015). This product was modeled for
dermal and inhalation exposure with DBP weight fractions of 0.01, 0.015, and 0.03 w/w in low,
medium, and high exposure scenarios.
Two adhesive products for home repair or construction bonding were identified with DBP content. One
anchoring adhesive used for anchoring metal rebar into cured concrete and masonry was reported to
have a DBP content of 0.1 to 5 percent (ITW Red Head. 2016). and one paste designed to watertight
details in construction was reported to have a DBP content of 10 to 30 percent (Vaproshield. 2018).
Both products are used outdoors in relatively small quantities and not applied in a manner expected to
generate significant aerosols. As such, these products were modeled for dermal exposure only.
Cleaning and Furnishing Care Products
Two cleaning and furnishing care products with DBP content were identified from a 2012 study on U.S.
consumer products (Dodson et al. 2012). Due to the different format and application, these items were
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modeled separately. One spray cleaning product used for tub and tile cleaning was identified with a
reported DBP content of 0.0001 w/w, which was applied for low, medium, and high exposure scenarios.
This product was assessed for inhalation, ingestion, and dermal contact. One polish/wax used for floors
and furniture was identified with a reported DBP content of 0.001 w/w, which was applied for low,
medium, and high exposure scenarios. This product was assessed for inhalation and dermal exposure.
Coatings
Several types of coating products were identified with DBP content. These items were grouped for
modeling according to expected consumer use patterns.
Six waterproofing coating products for roofs, decks, and walkway applications were identified with
DBP content. Three products had reported DBP content of 0.1 to 1 percent ( U . ^ l \ . ^ l ,1^1 ),
two products had reported DBP content of 2 to 3 percent (Structures Wood Care. 2016a. b), and one
product had reported DBP content of 0.05 to 10 percent (Lanco Mfg. Corp. 2016). Based on this data,
the weight fractions of 0.0005 w/w, 0.017 w/w, and 0.1 w/w were used for low, medium, and high
exposure scenarios. Though these products are for outdoor only use, inhalation exposure may be
significant due to relatively large volumes of product used and aerosol generation during spray
application. As such, these products were modeled for both inhalation and dermal exposures.
Two wood floor finish or coating products were identified with DBP content and were assessed for
inhalation and dermal contact. The products were reported to have DBP content of <2 percent (Franklin
Cleaning Technology. 2011) and 1 percent (Daly's Wood Finishing Products. 2015). Based on this data,
the weight fractions of 0.01, 0.015, and 0.02 w/w were used in low, medium, and high exposure
scenarios.
Two metal coating products were assessed for inhalation and dermal contact as application may occur
indoors (garage). One anti-fouling boat coating was identified with 2.5 to 10 percent DBP content (Rust-
Oleum Corporation. 2015). and one aluminum primer was identified with 1 to 2.5 percent DBP content
(Rust-Oleum Corporation. 2016). Based on this data, the weight fractions of 0.01 w/w, 0.04 w/w, and
0.1 were used for low, medium, and high exposure scenarios.
Rifle Powder
DBP was identified in several rifle powders manufactured by Western Powders, Inc. and the reported
DBP content was 0 to 10 percent (Western Powders Inc. 2015). Exposure to DBP in gunpowder was
qualitatively assessed as exposure is expected to be minimal. Exposure was considered in both DIY
bullet making and firing range scenarios. In DIY bullet making, exposure to DBP is limited due to the
precision required in measuring and handling the gunpowder. Exact quantities are critical to ensure safe
and effective ammunition, which necessitates the use of a powder measure - a device that dispenses
specific amounts of powder into each cartridge case. The powder measure typically consists of a hopper,
where the gunpowder is stored, and an adjustable measuring chamber that dispenses the powder without
manual contact. This process minimizes direct handling of the gunpowder, as the hopper only needs to
be refilled intermittently, significantly reducing the risk of both dermal and inhalation exposure to DBP.
The controlled, small-scale nature of powder dispensing also limits potential inhalation exposure. At
firing ranges, no data were available for DBP concentrations in air or particulate matter. However, the
exposure risk from DBP in these environments is expected to be minimal due to the small quantities
involved and the dispersion of these residues in the environment.
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664 Table 2-1. Summary of Consumer CPUs, Exposure Scenarios, and
Consumer
Condition of Use
Category
Consumer Condition of Use
Subcategory
Product/Article
Exposure Scenario and Route
Evaluated Routes
Inhalation"
Dermal
Ingestion
Suspended
Dust
Settled Dust
Mouthing
Automotive, fuel,
agriculture, outdoor
use products
Automotive care products
See automotive
adhesives
Use of product in DIY small-scale auto repair and
hobby activities. Direct contact during use; inhalation
of emissions during use
X
X
X
Construction, paint,
electrical, and metal
products
Adhesives and sealants
Adhesive for small
repairs
Direct contact during use
X
X
X
X
Construction, paint,
electrical, and metal
products
Adhesives and sealants
Automotive adhesives
Use of product in DIY small-scale auto repair and
hobby activities. Direct contact during use; inhalation
of emissions during use
X
X
X
Construction, paint,
electrical, and metal
products
Adhesives and sealants
Construction adhesives
Direct contact during use
X
X
X
X
Construction, paint,
electrical, and metal
products
Paints and coatings
Metal coatings
Use of product in DIY home repair and hobby
activities. Direct contact during use; inhalation of
emissions during use
X
X
X
Construction, paint,
electrical, and metal
products
Paints and coatings
Sealing and refinishing
sprays (indoor use)
Application of product in house via spray. Direct
contact during use; inhalation of emissions during use
s
X
X
X
Construction, paint,
electrical, and metal
products
Paints and coatings
Sealing and refinishing
sprays (outdoor use)
Application of product outdoors via spray. Direct
contact during use; inhalation of emissions during use
X
X
X
Furnishing,
cleaning, treatment
care products
Fabric, textile, and leather products
Synthetic leather
clothing
Direct contact during use
X
X
X
X
Furnishing,
cleaning, treatment
care products
Fabric, textile, and leather products
Synthetic leather
furniture
Direct contact during use; inhalation of emissions /
ingestion of airborne particulate; ingestion by
mouthing
b
b
b
Furnishing,
cleaning,
treatment/care
products
Cleaning and furnishing care products
Spray cleaner
Application of product in house via spray. Direct
contact during use; inhalation of emissions during use
s
X
X
X
Exposure Routes
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Evaluated Routes
Ingestion
Consumer
Condition of Use
Category
Consumer Condition of Use
Subcategory
Product/Article
Exposure Scenario and Route
Inhalation"
Dermal
Suspended
Dust
Settled Dust
Mouthing
Furnishing,
cleaning,
treatment/care
products
Cleaning and furnishing care products
Waxes and polishes
Application of product in house via spray. Direct
contact during use; inhalation of emissions during use
~
X
X
X
Furnishing,
cleaning,
treatment/care
products
Floor coverings; construction and
building materials covering large
surface areas including stone, plaster,
cement, glass and ceramic articles;
fabrics, textiles, and apparel
Vinyl flooring
Direct contact, inhalation of emissions / ingestion of
dust adsorbed chemical
b
b
b
X
Furnishing,
cleaning,
treatment/care
products
Floor coverings; construction and
building materials covering large
surface areas including stone, plaster,
cement, glass and ceramic articles;
fabrics, textiles, and apparel
Wallpaper
Direct contact during installation (teenagers and
adults) and while in place; inhalation of emissions /
ingestion of dust adsorbed chemical
b
b
b
X
Other uses
Novelty articles
Adult toys
Direct contact during use; ingestion by mouthing
X
X
X
Other uses
Automotive articles
Synthetic leather seats,
see synthetic leather
furniture
Direct contact during use; inhalation of emissions /
ingestion of airborne particulate; ingestion by
mouthing
b
b
b
X
Other uses
Automotive articles
Car mats
Direct contact during use; inhalation of emissions /
ingestion of airborne particulate; ingestion by
mouthing
b
b
b
X
Other uses
Chemiluminescent light sticks
Small articles with semi
routine contact; glow
sticks
Direct contact during use
X
X
X
X
Other uses
Lubricants and lubricant additives
No consumer products
identified. See adhesives
for small repairs
Current products were not identified. Foreseeable
uses were matched with the adhesives for small
repairs because similar use patterns are expected.
X
X
X
X
Packaging, paper,
plastic, hobby
products
Ink, toner, and colorant products
No consumer products
identified. See adhesives
for small repairs
Current products were not identified. Foreseeable
uses were matched with the adhesives for small
repairs because similar use patterns are expected.
X
X
X
X
Packaging, paper,
plastic, hobby
products
Packaging (excluding food
packaging), including rubber articles;
plastic articles (hard); plastic articles
Footwear
Direct contact during use
X
X
X
X
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Consumer
Condition of Use
Category
Consumer Condition of Use
Subcategory
Product/Article
Exposure Scenario and Route
Evaluated Routes
Inhalation"
Dermal
Ingestion
Suspended
Dust
Settled Dust
©X
c
2
3
O
s
(soft); other articles with routine
direct contact during normal use,
including rubber articles; plastic
articles (hard)
Packaging, paper,
plastic, hobby
products
Packaging (excluding food
packaging), including rubber articles;
plastic articles (hard); plastic articles
(soft); other articles with routine
direct contact during normal use,
including rubber articles; plastic
articles (hard)
Shower curtains
Direct contact during use; inhalation of emissions /
ingestion of dust adsorbed chemical while hanging in
place
%>' b
%/
%>' b
%>' b
X
Packaging, paper,
plastic, hobby
products
Packaging (excluding food
packaging), including rubber articles;
plastic articles (hard); plastic articles
(soft); other articles with routine
direct contact during normal use,
including rubber articles; plastic
articles (hard)
Small articles with semi
routine contact;
miscellaneous items
including a pen, pencil
case, hobby cutting
board, costume jewelry,
tape, garden hose,
disposable gloves, and
plastic bags/pouches
Direct contact during use
X
%/
X
X
X
Packaging, paper,
plastic, hobby
products
Toys, playground, and sporting
equipment
Children's toys (legacy)
Collection of toys; direct contact during use;
inhalation of emissions / ingestion of airborne PM;
ingestion by mouthing
%/ b
%/
%/ b
%/ b
%/
Packaging, paper,
plastic, hobby
products
Toys, playground, and sporting
equipment
Children's toys (new)
Collection of toys; direct contact during use;
inhalation of emissions / ingestion of airborne
particulate; ingestion by mouthing
%/ b
%/
%/ b
%/ b
%/
Packaging, paper,
plastic, hobby
products
Toys, playground, and sporting
equipment
Small articles with semi
routine contact;
miscellaneous items
including a football,
balance ball, and pet toy
Direct contact during use
X
%/
X
X
X
Packaging, paper,
plastic, hobby
products
Toys, playground, and sporting
equipment
Tire crumb and artificial
turf
Direct contact during use (particle ingestion via hand-
to-mouth)
%/
%/
l/ c
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Evaluated Routes
Ingestion
Consumer
Condition of Use
Category
Consumer Condition of Use
Subcategory
Product/Article
Exposure Scenario and Route
Inhalation"
Dermal
Suspended
Dust
Settled Dust
#J3
S
2
3
O
s
Disposal
Disposal
Down the drain products
and articles
Down the drain and releases to environmental media
X
X
X
X
X
Disposal
Disposal
Residential end-of-life
disposal, product
demolition for disposal
Product and article end-of-life disposal and product
demolition for disposal
X
X
X
X
X
DIY = Do-it-yourself
" Inhalation scenarios consider suspended dust and gas-phase emissions.
b Scenario used in Indoor Dust Exposure Assessment in Section 4. These indoor dust articles scenarios consider the surface area from multiple articles such as toys,
while furniture and flooring already have large surface areas. For these articles dust can deposit and contribute to significantly larger concentration of dust than single
small articles
cThe tire crumb and artificial turf ingestion route assessment considers all three types of ingestions, settled dust, suspended dust, and mouthing altogether, but results
cannot be provided separately has it was done for all other articles and products.
%# Quantitative consideration
* Qualitative consideration
665
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Qualitative Assessments
EPA performed qualitative assessments of the COU summarized in Table 2-2. A qualitative discussion
using physical and chemical properties and monitoring data for environmental media was performed to
support conclusions about down-the-drain and disposal practices and releases to the environment.
Table 2-2. CPUs and Products or Articles Without a Quantitative Assessment
Consumer Use
Category
Consumer Use
Subcategory
Product/Article
Comment
Disposal
Disposal
Down the drain products and
articles
Qualitative assessment done due to limited
information on source attribution of the
consumer COUs in drain water or wastewater.
Disposal
Disposal
Residential end-of-life
disposal, product demolition
for disposal
Qualitative assessment done due to limited
information on source attribution of the
consumer COUs in landfills.
Environmental releases may occur from consumer products and articles containing DBP via the end-of-
life disposal and demolition of consumer products and articles in the built environment or landfills, as
well as from the associated down-the-drain release of DBP. It is difficult for EPA to quantify these end-
of-life and down-the-drain exposures due to limited information on source attribution of the consumer
COUs. In previous assessments, the Agency has considered down-the-drain analyses for consumer
product scenarios where it is reasonably foreseen that the consumer product would be discarded directly
down-the-drain. For example, adhesives, sealants, paints, coatings, cleaner, waxes, and polishes can be
disposed down-the-drain while users wash their hands, brushes, sponges, and other product applying
tools. Although EPA acknowledges that there may be DBP releases to the environment via the cleaning
and disposal of adhesives, sealants, paints, coatings, and cleaning and furnishing care products, the
Agency did not quantitatively assess these products and instead provides a qualitative assessment.
DBP-containing products can be disposed when users no longer have use for them, or when they have
reached the product shelf life and are taken to landfills. All other solid products and articles in Table 2-1
can be disposed in landfills, or other waste handling locations that properly manage the disposal of
products like adhesives, sealants, paints, and coatings. Section 3.2 in th z Draft Environmental Media
and General Population and Environmental Exposure for Dibutyl Phthalate (DBP) ( E5b)
summarizes DBP monitoring data identified for landfills. Briefly, no studies were identified that
reported the concentration of DBP in landfills or in the surrounding areas in the United States, but DBP
was identified in sludge in wastewater plants in China, Canada, and the United States. DBP is expected
to have a high affinity to particulate (log Koc = 3.14-3.94) and organic media (log Kow = 4.5) that
would limit leaching to groundwater. Because of its high hydrophobicity and high affinity for soil
sorption, it is unlikely that DBP will migrate from landfills via groundwater infiltration. Nearby surface
waters, however, may be susceptible to DBP contamination via surface water runoff if DBP is not
captured before interacting with surface water.
2.2 Inhalation and Ingestion Modeling Approaches
The CEM Version 3.2 ( 23) was selected for the consumer exposure modeling as the most
appropriate model based on the type of input data available for DBP-containing consumer products. The
advantages of using CEM to assess exposures to consumers and bystanders are as follows:
• CEM model has been peer-reviewed (ERG. , );
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• CEM accommodates the distinct inputs available for the products and articles containing DBP,
such as weight fractions, product density, room of use, frequency and duration of use (see
Section 2.2.3 for specific product and article scenario inputs); and
• CEM uses the same calculation engine to compute indoor air concentrations as the higher-tier
Multi-Chamber Concentration and Exposure Model (MCCEM) but does not require measured
chamber emission values (which are not available for DBP).
CEM has capabilities to model exposure to DBP from both products and articles containing the
chemical. Products are generally consumable liquids, aerosols, or semi-solids that are used a given
number of times before they are exhausted. Articles are generally solids, polymers, foams, metals, or
woods, which are present within indoor environments for the duration of their useful life and may be
several years.
CEM 3.2 estimates acute dose rates and chronic average daily doses for inhalation, ingestion, and
dermal exposures of consumer products and articles. However, for the purpose of this assessment, EPA
performed dermal calculations outside of CEM, see Section 2.3 for approach description and input
parameters. CEM 3.2 acute exposures are for an exposure duration of 1 day while chronic exposures are
for an exposure duration of 1 year. The model provides exposure estimates for various lifestages. EPA
made some adjustments to match CEM's lifestages to those listed in the U.S. Centers for Disease
Control and Prevention (CDC) guidelines (CDC. 2021) and EPA's ,4 Framework for Assessing Health
Risks of Exposures to Children ( 006). CEM lifestages are re-labeled from this point forward
as follows:
• Adult
• Youth 2
• Youth 1
• Child 2
• Child 1
• Infant 2
• Infant 1
Exposure inputs for these various lifestages are provided in the EPA's CEM Version 3.2 Appendices.
2.2.1 Inhalation and Ingestion Modeling for Products
The calculated emission rates are then used in a deterministic, mass balance calculation of indoor air
concentrations. CEM employs different models for products and articles. For products, CEM 3.2 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. The model allows for further division of Zone 1 into a
near- and far-field component to accommodate situations where a higher concentration of product is
expected very near the product user during the period of use. 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. The modeled concentrations in the two zones are a function of the time-
varying emission rate in Zone 1, the volumes of Zones 1 and 2, the air flows between each zone and
outdoor air, and the air flows between the two zones. Following product use, the user and bystander may
follow one of three pre-defined activity patterns: full-time worker, part-time worker, and stay-at-home.
The activity use pattern determines which zone is relevant for the user and bystander and the duration of
the exposures. The user and bystander inhale airborne concentrations within these zones, which can vary
over time, resulting in the overall estimated exposure for each individual.
(21+ years) —~ Adult
(16-20 years) —~ Teenager and Young Adult
(11-15 years) —~ Young Teen
(6-10 years) —~ Middle Childhood
(3-5 years) —~ Preschooler
(1-2 years) —~ Toddler
(<1 year) —~ Infant
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The stay-at-home activity pattern assumes that occupants are inside the home a total of 21 hours per day,
in an automobile 1 hour per day, and outside 2 hours per day. Of the hours spent in the home, 10 hours
are in the bedroom, 7 hours are in the living room, 2 hours are in the kitchen, and 1 hour in both the
utility room and bathroom. However, normal activity patterns are overridden by the selection of product
users; any age group selected as a user remains in Zone 1 (or near-field if specified) for the duration of
product use.
CEM default air exchange rates for the building are from the Exposure Factors Handbook (U.S. EPA.
2011c). The default interzonal air flows are a function of the overall air exchange and volume of the
building as well as the openness of the room, which is characterized in a regression approach for closed
rooms and open rooms ( 23). See Section 2.2.3 for product scenario specific selections of
environment such as living room versus whole house, or indoor vs. outdoor and the air exchange rate
used per environment selection. Kitchens, living rooms, and the garage area are considered more open,
with an interzonal ventilation rate of 109 nrVhour. Bedrooms, bathrooms, laundry rooms, and utility
rooms are considered less open, and an interzonal ventilation rate of 107 nrVhour is applied. In instances
where the whole house is selected as the room of use, the entire building is considered Zone 1, and the
interzonal ventilation rate is therefore equal to the negligible value of 1 x 10~30 nrVhour. In instances
where a product might be used in several rooms of the house, air exchange rate was considered in the
room of use to ensure that effects of ventilation were captured.
2.2.2 Inhalation and Ingestion Modeling for Articles
For articles, the model comprises an air compartment (including gas phase, suspended particulates) and
a floor compartment (containing settled particulates). Semi-volatile organic compounds (SVOCs)
emitted from articles partition between indoor air, airborne particles, settled dust, and indoor sinks over
time. Multiple articles can be incorporated into one room over time by increasing the total exposed
surface area of articles present within a room. CEM 3.2 models exposure to SVOCs emitted from
articles via inhalation of airborne gas- and particle-phase SVOCs, ingestion of previously inhaled
particles, dust ingestion via hand-to-mouth contact, and ingestion exposure via mouthing. Abraded
particles are first emitted to the air and thereafter may deposit and resuspend from the surfaces. Abraded
particles, like suspended and settled particulate, are subject to cleaning and ventilation losses. Abraded
particles, both in the suspended and settled phases, are not assumed to be in equilibrium with the air
phase. Thus, the chemical transfer between particulates and the air phase is kinetically modeled in terms
of the two-phase mass transfer theory. In addition, abraded particles settled on surfaces are assumed to
have a hemispherical area available for emission, whereas those suspended in the air have a spherical
area available for emission.
In the inhalation scenarios where DBP is released from an article into the gas-phase, the article
inhalation scenario tracks chemical transport between the source, air, airborne and settled particles, and
indoor sinks by accounting for emissions, mixing within the gas phase, transferring to particulates by
partitioning, removal due to ventilation, removal due to cleaning of settled particulates and dust to which
DBP has partitioned, and sorption or desorption to/from interior surfaces. The emissions from the article
were modeled with a single exponential decay model. This means that the chronic and acute exposure
duration scenarios use the same emissions/air concentration data based on the weight fraction of the
chemical in the article but have different averaging times. The acute data uses concentrations for a 24-
hour period at the peak of the simulated emissions, while the chronic data was averaged over the entire
1-year period. Because air concentrations for most of the year are significantly lower than the peak
value, the air concentrations used in chronic dose calculations are usually lower than that used to
calculate an acute dose.
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2.2.3 CEM Modeling Inputs and Parameterization
The COUs that were evaluated for DBP consisted of both products and articles. The embedded models
within CEM 3.2 that were used for DBP are listed in Table 2-3. As dermal exposure was modeled
separately, only inhalation and ingestion routes were evaluated using CEM.
Table 2-3. CI
CM 3.2 Model Codes and Descriptions
Model Code
Description
El
Emission from Product Applied to a Surface Indoors Incremental Source Model
E2
Emission from Product Applied to a Surface Indoors Double Exponential Model
E3
Emission from Product Sprayed
E6
Emission from Article Placed in Environment
AINHl
Inhalation from Article Placed in Environment
AING1
Ingestion After Inhalation
AING2
Ingestion of Article Mouthed
AING3
Incidental Ingestion of Dust
P ING1
Ingestion of Product Swallowed
P INH2
Inhalation of Product Used in an Environment
Table 2-4 presents a crosswalk between the COU subcategories with either a predefined or generic
scenario. Models were generated to reflect specific use conditions as well as physical and chemical
properties of identified products and articles. In some cases, one COU mapped to multiple scenarios, and
in other cases one scenario mapped to multiple COUs. Table 2-4 provides data on emissions model and
exposure pathways modeled for each exposure scenario. Emissions models were selected based upon
physical and chemical properties of the product or article and application use method for products.
Exposure pathways were selected to reflect the anticipated use of each product or article. The article
model Ingestion of Article Mouthed (A ING2) was only evaluated for the COUs where it was
anticipated that mouthing of the product could occur. For example, it is unlikely that a child would
mouth flooring or wallpaper, hence the A ING2 Model was deemed inappropriate for estimating
exposure for these COUs. Similarly, solid articles with small surface area are not anticipated to
contribute significantly to inhalation or ingestion of DBP sorbed to dust/PM and were therefore not
modeled for these routes (A_ING1, A_ING3). Note that products and articles not assessed in CEM
(adhesives for small repairs, construction adhesives, footwear, synthetic leather clothing, small articles
with potential for semi-routine contact) are not listed in this table; modeling for these items was
performed outside of CEM as described in Sections 2.3 and 2.5.
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820 Table 2-4. Crosswalk of COU Subcategories, CEM 3.2 Scenarios, and Relevant CEM 3.2 Models
821 Used for Consumer Modeling
Consumer COU
Sub-CO U
Product/Article
Emission Model and
Exposure Pathway(s)
CEM Saved Analysis
Other
Novelty products
Adult toys
AING2
Rubber articles: with
potential for routine
contact (baby bottle
nipples, pacifiers, toys)
Construction, paint,
electrical, and metal
products
Adhesives and sealants,
including fillers and
putties
Automotive
adhesives
El, PINH2 (near-
field, users), PINHl
(bystanders)
Glue and adhesives
(small scale)
Other use
Automotive products,
other than fluids
Car mats
E6, A INH1, A ING1,
AING3
Rubber articles: with
potential for routine
contact (baby bottle
nipples, pacifiers, toys)
Packaging, paper,
plastic, hobby products
Toys, playground, and
sporting equipment
Children's toys
(legacy)
E6, A INH1, A ING1,
AING2, A ING3
Rubber articles: with
potential for routine
contact (baby bottle
nipples, pacifiers, toys)
Packaging, paper,
plastic, hobby products
Toys, playground, and
sporting equipment
Children's toys
(new)
E6, A INH1, A ING1,
AING2, A ING3
Rubber articles: with
potential for routine
contact (baby bottle
nipples, pacifiers, toys)
Construction, paint,
electrical, and metal
products
Paints and coatings
Metal coatings
Generic P3 E3
E3, P INH2 (Near-
field, users), PINHl
(bystanders)
Construction, paint,
electrical, and metal
products
Paints and coatings
Sealing and
refinishing sprays
(indoor use)
Generic P3 E3
E3, P INH2 (Near-
field, users), PINHl
(bystanders)
Construction, paint,
electrical, and metal
products
Paints and coatings
Sealing and
refinishing sprays
(outdoor use)
Generic P3 E3
E3, P INH2 (Near-
field, users), P INHl
(bystanders)
Packaging, paper,
plastic, hobby products
Packaging (excluding food
packaging), including
rubber articles; plastic
articles (hard); plastic
articles (soft)
Shower curtains
E6, A INH1, A ING1,
AING3
Plastic articles: other
objects with potential
for routine contact
(toys, foam blocks,
tents)
Furnishing, cleaning,
treatment care products
Fabric, textile, and leather
products
Synthetic leather
furniture
E6, A INH1, A ING1,
A ING2, A ING3
Leather Furniture
Furnishing, cleaning,
treatment/care products
Cleaning and furnishing
care products
Tub and tile cleaner
All-purpose spray
cleaner
E3, P INH2 (Near-
field, users), PINHl
(bystanders)
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Consumer COU
Sub-CO U
Product/Article
Emission Model and
Exposure Pathwav(s)
CEM Saved Analysis
Furnishing, cleaning,
treatment/care products
Floor coverings;
construction and building
materials covering large
surface areas including
stone, plaster, cement,
glass, and ceramic articles;
fabrics, textiles, and
apparel
Vinyl flooring
E6, A INH1, A ING1,
AING3
Plastic articles: vinyl
flooring
Furnishing, cleaning,
treatment/care products
Floor coverings;
construction and building
materials covering large
surface areas including
stone, plaster, cement,
glass, and ceramic articles;
fabrics, textiles, and
apparel
Wallpaper (in
place)
E6, A INH1, A ING1,
AING3
Fabrics: curtains, rugs,
wall coverings
Furnishing, cleaning,
treatment/care products
Cleaning and furnishing
care products
Waxes and polishes
All-purpose waxes and
polishes (furniture,
floor, etc.)
E3, P INH2 (Near-
field, users), PINHl
(bystanders)
In total, the specific products representing 11 COUs for DBP were mapped to 20 scenarios, 14 of which
were modeled in CEM. Relevant consumer behavioral pattern data {i.e., use patterns) and product-
specific characteristics were applied to each of the CEM scenarios and are summarized in Sections
2.2.3.1 and 2.2.3.2.
2.2.3.1 Key Parameters for Articles Modeled in CEM
Key input parameters for articles vary based on the exposure pathway modeled. For inhalation and dust
ingestion, higher concentrations of DBP in air and dust result in increased exposure. This may occur due
to article specific characteristics that allow for higher emissions of DBP to air and/or environment
specific characteristics such as smaller room volume and lower ventilation rates. Key parameters that
control DBP emission rates from articles in CEM 3.2 models are weight fraction of DBP in the material,
density of article material (g/cm3), article surface area (m2), and surface layer thickness (cm); an
increase in any of these parameters results in increased emissions and greater exposure to DBP. A
detailed description of derivations of key parameter values used in CEM 3.2 models for articles is
provided below, and a summary of values can be found in Table 2-5. Note that articles not modeled for
inhalation exposure in CEM (clothing, footwear components, tire crumb rubber, and small articles with
potential for semi-routine dermal contact) are not described here or included in the table. However, tire
crumb rubber was assessed for inhalation exposure outside of CEM to accommodate use of empirical
data for concentrations of DBP in air; details of this approach are provided in Section 2.4.
Weight fractions of DBP were calculated for each article as outlined in Section 2.1.1. Material density
was assumed to be a standard value for PVC of 1.4 g/cm3 in all articles. Values for article surface layer
thickness were taken from CEM default values for scenarios with emissions from the same or similar
solid material. CEM default values for parameters used to characterize the environment (use volume, air
exchange rate, and interzonal ventilation rate) were used for all models. Due to the high variability and
uncertainty of article surface areas, high, medium, and low values were generally estimated for each
item with the goal of capturing a reasonable range of values for this parameter. Assumptions for surface
area estimates are outlined below.
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Car Mats
Based on a survey of car mat sets available on manufacturers websites, there was little variability in
surface area and mats were sold in sets with two front mats approximately 30 inches x 20 inches and
two back floor mats approximately 20 inches x 20 inches. Based on these dimensions the total surface
area modeled was 1.29 m2 As there was little observed variation in dimensions, this value was used in
the low, medium, and high scenarios.
Children's Toys
Children's toys generally have a small surface area for an individual item, but consumers may have
many of the same type of item in a home. As phthalates are ubiquitous in PVC material, it is reasonable
to assume that in a collection of toys all of the items may have DBP content. As such, surface area for
these items was estimated by assuming that a home has several of these items rather than one. The
surface area of new and legacy toys was varied for the low, medium, and high exposure scenarios based
on EPA's professional judgment of the number and size of toys present in a bedroom. The low-intensity
use scenario was based on 5 small toys measuring 15cmxl0cm><5 cm, the medium intensity use
scenario was based on 20 medium toys measuring 20 cm x 15 cm x 8 cm, and the high intensity use
scenario was based on 30 large toys measuring 30 cm x 25 cm x 15 cm.
Synthetic Leather Furniture
For textile furniture components, each scenario consisted of a couch and loveseat set, with the surface
area varied in low, medium, and high exposure scenarios to reflect the variability observed in standard
sizes available for purchase. The low, medium, and high surfaces areas, respectively, are based on
prisms measuring 60 inches x 30 inches x 25 inches, 80 inches x 36 inches x 30 inches, and 100 inches
x 42 inches x 35inches for a couch and 48inches x 30inches x 25inches, 60 inches x 36 inches x 30
inches, and 72 inches x 42 inches x 35 inches for a loveseat. The measurements were compiled from
furniture retail store descriptions. EPA added the low surface areas for a couch and loveseat together to
estimate exposures to smaller furniture in the low-end scenario, and similarly for the medium and high
estimates. EPA assumes the bottom side of the furniture is not covered with the same material.
Shower Curtains
Based on a survey of shower curtains available on manufacturers' websites, there was little variability in
surface area. EPA used manufacturer specifications for a shower curtain's dimensions (1.83 m x 1.78 m)
to estimate surface area and multiplied by 2 to account for both sides. As there was little variability for
this item, this surface area value was used in the low, medium, and high exposure scenarios.
Vinyl Flooring
To estimate surface areas for flooring materials, it was assumed that the material was used in 100, 50,
and 25 percent of the total floor space. The value for whole house floor space was back calculated from
the CEM house volume (492 m3) and an assumed ceiling height of 8 ft, and the resulting values were
applied in high, medium, and low exposure scenarios.
Wallpaper
The surface area of wallpaper in a residence was varied for the low, medium, and high exposure
scenarios. The medium value of 100 nr is based on Exposure Factors Handbook Table 9-13 (]j S J_TA_
2( ). This value was scaled to 200 and 50 nr for the high and low exposure scenarios based on
professional judgment.
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898 Table 2-5. Summary of Key Parameters for Inhalation and Dust Ingestion Exposure to DBP from
899 Articles Modeled in CEM 3.2
Article
Exposure
Scenario
Level
Weight
Fraction "
Density
(g/cm3)b
Article
Su rt'acc
Area (m2) c
Su rt'acc
Layer
Thickness
(cm) d
Use
Environment'
Use Environ
Volume (m3)''
Inter/one
Ventilation
Rate (m3/h)''
Car mats
High
0.00014
1.4
1.29
0.01
Automobile
2.4
9.5
Medium
0.00014
Low
0.00014
Children's toys
(legacy)'
High
0.001
1.4
9.45
0.01
Bedroom
36.0
107.01
Medium
0.001
2.32
Low
0.001
0.28
Children's toys
(new) g
High
0.01
1.4
9.45
0.01
Bedroom
36.0
107.01
Medium
0.0075
2.32
Low
0.005
0.28
Synthetic
leather
furniture
High
0.0007
1.4
17
0.01
Living room
50.0
108.98
Medium
0.0001
12
Low
0.0001
7.9
Shower
curtains
High
0.0173
1.4
6.5
0.01
Bathroom
15.0
107.01
Medium
0.011
Low
0.0064
Vinyl flooring
High
0.000129
1.4
202
0.01
Whole house
492.0
1.0E-30
Medium
0.000129
101
Low
0.0001
50.5
Wallpaper (In
place)
High
0.000030
1.4
200
0.01
Whole house
492.0
1.0E-30
Medium
0.000017
100
Low
0.000009
50
" See Section 2.1.1 for weight fraction sources and discussion.
b Used density of PVC from various sources, see DBP Draft Consumer Exposure Analysis Spreadsheet (U.S. EPA, 2025a).
c See text related to article in this section.
d CEM default for the emission scenario and saved analysis.
e Professional judgment based on likeliness of article presence.
^Legacy toys scenarios consider weight fractions in toys that are not limited to 0.1% and may be older than the 2017 CSPC
phthalate rule, 16 CFRpart 1307.
g New toys scenarios consider the application of the U.S. CSPC final phthalates rule established in 2017 (16 CFR Part 1307)
that bans children's toys and childcare articles from containing more than 0.1% of five phthalates, including DBP. The
identified weight fractions in the legacy toys scenario were not limited to 0.1%.
900
901 Environmental Parameters
902 The room of use selected for modeling affects the time occupants spend in the environment while
903 products are actively emitting BBP, the total volume of air in the room, and ventilation rates. Default
904 values are provided in CEM for use environment and ventilation rates in each room, which may be
905 modified by the user. Time spent in each use environment is defined by activity patterns as described in
906 Section 2.2. EPA used CEM defaults for the articles assessed.
907
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Mouthing Exposure
For mouthing exposure, key parameters include the rate of chemical migration from the article to saliva
(|ig/cm2/h), surface area mouthed (cm2), and duration of mouthing (min/day). Derivation of these inputs
is outlined below.
Chemical Migration Rate: Phthalates added to plastic products are not chemically-bound to the polymer
matrix, allowing for migration through the material and release into saliva during mouthing. The rate of
phthalate migration and release to saliva depends upon several factors, including physicochemical
properties of the article polymer matrix, phthalate concentration in the polymer, physical mechanics of
the individual's mouth during mouthing (e.g., sucking, chewing, biting, etc), and chemical composition
of saliva. In addition, physicochemical properties of the specific phthalate such as size, molecular
weight, and solubility have a strong impact on migration rate to saliva.
Chemical migration rates of phthalates to saliva may be measured by in vitro or in vivo methods. While
measurement assays may be designed to mimic mouthing conditions, there is not a consensus on what
constitutes standard mouthing behavior. As a result, there is considerable variability in assay methods,
which is expected to affect the results. Because of the aggregate uncertainties arising from variability in
physical and chemical composition of the polymer, assay methods for in vitro measurements, and
physiological and behavioral variability in in vivo measurements, migration rates observed in any single
study were not considered adequate for estimating this parameter. The chemical migration rate of DBP
was estimated based on data compiled in a review published by the Denmark EPA in 2016 (Danish
E ). For that review, data were gathered from existing literature for in vitro migration rates from
soft PVC to artificial sweat and artificial saliva, as well as in vivo tests when such studies were available.
The authors used 23 values taken from 3 studies (Danish < < \ _*-«h«, Niino et ai. 2003; Niino et ai.
2001) for chemical migration rates of DBP to saliva from a variety of consumer goods measured with
varying mouthing approaches methods. These values were then subdivided into mild, medium, and
harsh categories based on the mouthing approach method used to estimate migration. Harsh mouthing
method is used for vigorous chewing of an article relative to mild mouthing approaches. There is
considerable variability in the measured migration rates, but there was not a clear correlation between
weight fraction of DBP and chemical migration rate.
As such, the same chemical migration rates were applied to all articles regardless of DBP weight
fraction. As no values were reported for DBP chemical migration rate using medium assay conditions,
mean values under mild and harsh assay conditions were used in the low and high exposure scenarios,
respectively and the midpoint between the two values was used in the medium exposure scenario. DBP
chemical migration rate values used in low, medium, and high exposure scenarios were 0.17, 24.3, and
48.5 |ig/cm2-h, respectively; these values are expected to capture the range of reasonable values for this
parameter, see Table 2-6. EPA calculated a high-intensity use of adult toys using harsh mouthing
approaches as part of the screening approach; however, recognizing that this highly conservative use
pattern is very unlikely behavior, it is not to be used to estimate risk. The Agency did not identify use
pattern information regarding adult toys.
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951
952
953
954
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956
957
958
959
960
961
962
963
964
965
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967
968
969
970
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Table 2-6. Chemical Migration Rates Observed for DBP Under Mild, Medium, and
Harsh Extraction Conditions
Migration Rate (jig/cm2/h)
a
Mouthing Approach
Min
Mean (Standard
Deviation)
Max
Mild
0.04
0.17 b (1.39)
5.8
Medium
-
24.3 bc
-
Harsh
-
48.5 b
-
a Information from Tables 17. 18. and 19 in (Danish EPA, 2016).
h Selected values for assessment.
c Calculated from the average of the mild and harsh means.
Mouthing Surface Area
The parameter "mouthing surface area" refers to the specific area of an object that comes into direct
contact with the mouth during a mouthing event. A standardized value of 10 cm2 for mouthing surface
area is commonly used in studies and a default in CEM to estimate mouthing exposure in children
(Danish EPA. 2010; Niino et at.. 2003; Niino et at.. 2001). This standard value is based on empirical
data reflecting typical mouthing behavior in young children, providing a reliable basis for estimating
exposure levels and potential health risks associated with mouthing activities. The value of 10 cm2 was
thus chosen for all mouthing exposure models for children.
Mouthing of adult toys was only modeled for adults and teenagers. Object mouthing is not commonly
observed behavior in adults and teens, and as such there are not standard values for mouthing surface
area. Although mouthing is uncommon for adults and teenagers, EPA assessed this potential behavior
for adult toys only to consider associated exposures for selected individuals who may exhibit this
behavior. The Agency did not identify adult toys use information with regards to surface area. To
determine a reasonable value for mouthing surface area for adults and teens, EPA identified two studies
that reported the surface area of the entire oral cavity in adults (Assy et at.. 2020; Collins and Dawes.
1987). The mean surface area reported in Collins et al. (1987) was 215 cm2, and the mean value reported
in Assy et al. (2020) was 173 cm2. Based on these data, EPA assumes approximately 200 cm2 is a
reasonable estimate for the total surface area in the oral cavity. However, this value accounts for all
surface area—including teeth, gums, the ventral surface of the tongue, and mouth floor—which is a
significant overestimation of surface area which would be in contact with an object. As such, it was
assumed that 50 percent of the total surface area might reasonably represent mouthing surface area, and
a value of 100 cm2 was used for this parameter. This corresponds approximately with a one-ended
cylinder having a radius of 2 cm and length of 7 cm. This value is similar, though slightly lower than the
value of 125 cm2 used for adult toy mouthing area in an European Chemicals Agency assessment
(ECHA. 2013).
Mouthing Duration
Mouthing durations were obtained from EPA' Exposure Factors Handbook Table 4-23 (
201lc). which provides mean mouthing durations for children between 1 month and 5 years of age,
broken down by age groups expected to be behaviorally similar. Values are provided for toys, pacifiers,
fingers, and other objects. For this assessment, values for toys were used for legacy and new children's
toys. Values for other object were used for all other items assessed for mouthing by children {i.e.,
synthetic leather furniture). The data provided in the Handbook were broken down into more age groups
than CEM. For example, it provides different mouthing durations for infants 12 to 15, 15 to 18, 18 to 21,
and 21 to 24 months of age; CEM, in contrast, has only one age group for infants under 1 year of age.
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To determine the mouthing duration in CEM, all relevant data in the Exposure Factors Handbook table
(U.S. EPA. 2011b) were considered together. The minimum value by item type within each age group
was used in the low exposure scenario, maximum value was used in the high exposure scenario, and the
mean value (average across the age groups provided in the Handbook) was used in the medium exposure
scenario as shown in Table 2-7. For mouthing of adult toys, values of 60, 30, and 15 minutes per day
were used in the high, medium, and low exposure scenarios, respectively. As there were no available
data for these values, they were chosen to encompass the range of expected mouthing durations based on
professional judgment.
Table 2-7. Mouthing Durations for Children for Toys and Other Objects
Estimated Mean Daily Mouthing Duration Values
from Table 4-23 in Exposure Factors Handbook
(minutes/day)
Mouthing Durations for CEM Age Groups
(minutes/day)
Item
Mouthed
Reported Age Group
CEM Age Group: Infants <1 Year
1-3 Months
3-6 Months
6-9 Months
9-12
Months
High Exposure
Scenario
Med. Exposure
Scenario
Low Exposure
Scenario
Toy
1.0
28.3
39.2
23.07
39.2
22.9
1.0
Other Object
5.2
12.5
24.5
16.42
24.5
14.7
5.2
Item
Mouthed
Reported Age Group
CEM Age Group: Infants 1-2 Years
12-15
Months
15-18
Months
18-21
Months
21-24
Months
High Exposure
Scenario
Med. Exposure
Scenario
Low Exposure
Scenario
Toy
15.3
16.6
11.1
15.8
16.6
14.7
11.1
Other Object
12.0
23.0
19.8
12.9
23.0
16.9
12.0
Item
Mouthed
Reported Age Group
CEM Age Group: Small Child 3-5 Yars
2 Years
3 Years
4 Years
5 Years
High Exposure
Scenario
Med. Exposure
Scenario
Low Exposure
Scenario
Toy
12.4
11.6
3.2
1.9
12.4
7.3
1.9
Other Object
21.8
15.3
10.7
10.0
21.8
14.4
10.0
2.2.3.2 Key Parameters for Liquid and Paste Products Modeled in CEM
CEM models for liquid and paste products only evaluated exposure by inhalation. Higher concentrations
of DBP in air result in increased inhalation exposure. This may occur due to product formulation or use
patterns that allow for higher emissions of DBP to air and/or environment specific characteristics such
as smaller room volume and lower ventilation rates. Key parameters that control DBP emission rates
from products in CEM 3.2 Models are weight fraction of DBP in the formulation, duration of product
use, mass of product used, and frequency of use. Any increase in these parameters results in higher
chemical exposure from product use.
CEM default values for key parameters for exposure modeling including product mass used, duration of
use, and frequency of use were not available for the specific products identified with DBP content. As
such, values for these parameters were based on professional judgment, which incorporated information
from product labels and technical specifications as well as information obtained from an informal survey
of customer reviews on e-commerce sites. This information was synthesized to better understand how
consumers use these products and professional judgment was applied to develop specific values
expected to capture a realistic range of values for each parameter. Product densities were taken from
product specific technical specifications and SDSs, when possible. In instances where no data were
available for a product type a density obtained for a similar product was used as a proxy. A detailed
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description of derivations of key parameter values used in CEM 3.2 Models for liquid and paste
products is provided below, and a summary of values be found in Table 2-8. Note that articles not
modeled for inhalation exposure are not included in the table.
Mass of Product Used
Several products were identified that may be used in a wide variety of DIY home and auto improvement
and repair projects, see Section 2.1.2. For these products, the mass of product applied in each scenario
was based on the reasonable assumption that the volume in which products are sold is adequate for the
tasks they are intended for. Mass of product used inputs was based on a survey of consumer available
products fitting the COU description on manufacturers websites, see DBP Product Review tab (links and
products available) in Draft Risk Evaluation for Dibutyl Phthalate (DBP) - Supplemental Information
File: Consumer Exposure Analysis ( ,025a). This section summarizes the identified
information for each product. Auto adhesives were sold in 1.7 or 7.6 fluid oz containers, and coatings
used for sealing and refinishing outdoor surfaces were available in 1- and 5-gallon cans. For these
products, the high exposure scenario assumed that the entire container with the larger volume is used,
reflecting scenarios where a large project or extensive application is undertaken. The low exposure
scenario assumed that the entire container with the smaller volume is used, representing more common
or average usage for routine maintenance or smaller projects. The medium exposure scenario used the
average of the two values.
Metal coating products were available only in a single size (32 fluid oz). For these products, the high
exposure scenario for this product assumed that the entire mass of the product container is used, medium
exposure scenario assumed half the container's mass was used, and low exposure scenarios assumed a
quarter of the container's mass was used, corresponding to minimal use for minor repairs or touch-ups.
This approach is consistent with observations of consumer reviews for individual products on vendor
websites, which indicated diverse usage patterns among consumers including small, medium, and large
projects.
For floor refinishing products, consumer reviews and technical specifications did not indicate that these
products are often used for small repair or patching projects. A more specific scenario was developed in
which a total of four rooms were assumed to be refinished. Each room was assumed to be 50 m3 (CEM
default value for living room), with a square footage of 222 ft2. Technical specifications for these
products indicated that each gallon of product would cover between 400 to 700 ft2 per gallon, depending
upon floor conditions, and application of three coats was recommended. This range of coverage was
used to estimate low and high values for product mass used and a value of 500 ft2 per gallon was used to
estimate a medium value for product mass used per coat of product. Based on this information, the total
mass of product used in each room (assuming three coats of product) were 3,755, 5,256, and 6,571
grams for the low, medium, and high exposure scenarios, respectively.
For home cleaning products, values for mass of product used were derived from default values for
similar products in CEM. Tub and tile spray used default values from the All Purpose Spray Cleaner
Scenario and wax and polish products used default values from the All Purpose Wax and Polishes
Scenario.
Duration of Use
For sealing and refinishing sprays for outdoor environments, large projects could be a full day of work,
while smaller projects may be accomplished more quickly, so duration of use for high, medium, and low
exposure scenarios were assumed to be 480, 240, and 120 minutes. Automotive adhesives, construction
adhesives, and metal coating products are expected to be used in comparatively smaller scale projects
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and were thus modeled at use durations of 120, 60, and 30 minute. For indoor floor refinishing products,
an informal survey of public forums dedicated to DIY home renovation projects indicated that most
consumers spend between 30 minutes and 1 hour applying each coat when refinishing floors, see DBP
Product Review tab in U.S. EPA (2025a). Based on this information the total time to apply three coats of
these products was estimated to be 90, 120, and 270 minutes in low, medium, and high scenarios,
respectively.
For home cleaning products, values for duration of use were derived from default values for similar
products in CEM. Tub and tile spray used default values from the All Purpose Spray Cleaner Scenario
and wax and polish products used default values from the All Purpose Wax and Polishes scenario.
Frequency of Use
The frequency of use input is used in the calculation of acute and chronic exposure durations. Acute
exposures are for an exposure duration of one day and chronic exposures are for an exposure duration of
1 year. For sealing and refinishing sprays for outdoor environments, floor refinishing products,
automotive adhesives, and construction adhesives; given the significant work required to prepare and
clean up after use as well as the relatively niche use, frequency of use of these products is not anticipated
to be routine for consumers. For indoor floor refinishing products, each room was assumed to be
finished in a single day, for a total of 4 days per year. All other products listed above are assumed to be
used for a single project each year, which may take 2 days to complete. For metal coating products,
daily use was not considered likely, but the product could reasonably be used weekly for hobby projects
or a variety of small projects. Therefore, this product was modeled at a use frequency of 52 times per
year. Tub and tile cleaner and wax and polish products were also modeled at a frequency of 52 times per
year under the assumption that they may be used in weekly cleaning activities. For all liquid and paste
products, acute frequency was modeled as one use per day.
Environmental Parameters
The room of use selected for modeling affects the time occupants spend in the environment while
products are actively emitting DBP, the total volume of air in the room, and ventilation rates. Default
values are provided in CEM for use environment and ventilation rates in each room, but these may be
modified by the user. Time spent in each use environment is defined by activity patterns as described in
Section 2.2 and cannot be modified for individual environments within CEM. As such, it is sometimes
required to select an environment of use based on the activity pattern required and modify the
environmental parameters to reflect conditions in the home area in which a product is expected to be
used.
In this assessment, the majority of the products modeled used CEM defaults for all parameters in the
specified room of use. However, for indoor floor refinishing products, the garage environment was
selected as CEM activity patterns do not include any time in this room. This was chosen to reflect the
fact that occupants are not expected to spend time in rooms with recently refinished floors outside of
time spent actively applying the products. For this model, room volume and ventilation rates were
changed from CEM default values for garage to CEM default values for living room as shown in Table
2-8.
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1110 Table 2-8. Summary of Key Parameters for Products Modeled in CEM 3.2
Product
Exposure
Scenario
Level
Weight
Fraction "
Density
(g/cm3)b
Duration
of Use
(min)'
Product
Mass Used
(8)'
Chronic
Frcq. of
Use
(year-1)
Acute Freq.
of Use
(day-1)
Use Environ.
Volume (m3)'
Air
Exchange
Rate, Zone 1
and Zone 2
(hr1) '
Inter/,one
Ventilation
Rate (m3/h) f
Automotive
adhesives
H
0.3
1.78
120
400
2
1
Garage; 90
0.45
109
M
0.081833
60
245
L
0.01
30
90
Metal coatings
H
0.1
1.51
120
1,427
52
1
Garage; 90
0.45
109
M
0.04
60
713
L
0.01
30
357
Indoor floor
refinishing
products
H
0.02
1.04
270
6,571
4
1
Garage; 50
0.45
109
M
0.015
180
5,256
L
0.01
90
3,755
Sealing and
refinishing sprays
(outdoor use)
H
0.1
1.37
480
26,003
2
1
Outside; 492
0.45
1.0E-30
M
0.016688
240
15,602
L
0.0005
120
5,201
Spray cleaner
H
0.0001
1.00
30
60
52
1
Bathroom; 15
0.45
107
M
0.0001
15
30
L
0.0001
5
10
Waxes and
polishes
H
0.001
1.02
60
80
52
1
Living Room; 50
0.45
109
M
0.001
30
50
L
0.001
15
30
" See Section 2.1.2. High intensity use value is the reported range maximum, the low intensity use value is the reported range minimum, and the medium intensity use
value is the mean from the reported maximum and low.
b Used product SDS reported density value, see Section 2.1.2.
c Professional iudement based on product use descriptions, available in DBP Product Review tab in U.S. EPA (2025a).
d Based on product use descriptions, available in DBP Product Review tab in U.S. EPA (2025a).
e Use environment was determined based on product manufacturer use description.
' CEM default. For all scenarios, the near-field modeling option was selected to account for a small personal breathing zone around the user during product use in which
concentrations are higher, rather than employing a single well-mixed room. A near-field volume of 1 m3 was selected.
1111
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2.3 Dermal Modeling Approach
This section summarizes the available dermal absorption data related to DBP, the interpretation of the
dermal absorption data, and dermal absorption modeling efforts, while uncertainties associated with
dermal absorption estimation in Section 4. While inhalation and ingestion pathways were modeled using
CEM (Section 2.2), dermal modeling for liquid and solid products was done using the approach
described below. Dermal data were sufficient to characterize consumer dermal exposures to liquids or
formulations containing DBP (Section 2.3.2), but not sufficient to estimate dermal exposures to solids or
articles containing DBP. Therefore, the modeling described in Section 2.3.1 was used to estimate dermal
exposures to solids or articles containing DBP. For solid products, EPA used the steady-state
permeability coefficient equations defined within the CEM model in a computational approach that
bypassed the need for certain inputs required by CEM, like weight fractions and migration rates. Dermal
exposures to vapors are not expected to be significant due to the extremely low volatility of DBP
(Henry's Law constant is 1.81/10 6 atmm3/mol at 25 °C, s qq Draft Physical Chemistry and Fate and
Transport Assessment for Dibutyl Phthalate (DBP) TSD ( 024a)). and therefore, are not
included in the dermal exposure assessment of DBP.
For liquid products, the concentration of DBP often exceeds its saturation concentration because DBP
molecules form weak chemical bonds with polymer chains in the product/article, which favors migration
out of the polymer. During direct dermal contact DBP can migrate to the aqueous phase available in the
skin surface or be weakly bound to the polymer. The fraction of DBP associated with polymer chains is
less likely to contribute to dermal exposure as compared to the aqueous fraction of DBP because the
chemical is strongly hydrophobic. As such, use of the CEM model for dermal absorption, which relies
on total concentration rather than aqueous saturation concentration would greatly overestimate exposure
to DBP in liquid chemicals.
For solid articles, as there was no empirical data available, EPA used a theoretical framework based on
physical and chemical properties of DBP for all solid items except tire crumb rubber. For tire crumb
rubber, the method described below was not used as the surface area in contact with the material could
not be estimated with confidence based on available data. A detailed description of dermal uptake
modeling for DBP from tire crumb rubber is described in detail in Section 2.5.
2.3.1 Dermal Absorption Data
Dermal absorption data related to DBP were identified in the literature. EPA identified six studies
directly related to the dermal absorption of DBP. Of the six available studies, the Agency identified one
study that was most reflective of DBP exposure from consumer liquid products and formulations (Doart
et at.. 2010):
• Recent studies were preferred that used modern dermal testing techniques and guidelines for in
vivo and in vitro dermal absorption studies (i.e., OECD Guideline 427 (OECD. 2004a) and
Guideline 428 ( 34b)).
• Studies of human skin were preferred over animal models, and when studies with human skin
were not suitable (see other criteria), studies of guinea pig skin were preferred over rat studies.
Guinea pig skin absorption is closer to human skin than rats, per OECD 2004a).
• Studies of split skin thickness were preferred over studies of full thickness. Generally, studies
should provide information on dermatoming methods and ideally provide a value for thickness in
accordance with OECD guideline 428 (OECD. 2004b). which recommends a range of 400 to 800
[j,m or less than 1 mm.
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• In vivo or freshly excised (non-frozen) skin studies were preferred, if there was not a significant
delay between skin sample retrieval and assay initiation.
• Studies using an aqueous vehicle type were preferred over neat chemical studies as there is
greater relevance to consumer product formulations and subsequent exposure, and due to greater
uncertainties from neat chemical resulting in lower absorptions than formulations that may
enhance dermal absorption.
• Studies with exposure times that are relevant or closer to dermal durations used in the consumer
exposure assessment were preferred, see Section 2.3.4.
• Studies with reported sample temperatures that represent human body temperature, in a
humidity-controlled environment were preferred.
Doan et al. C ) conducted in vivo and ex vivo experiments in female hairless guinea pigs to compare
absorption measurements using the same dose of DBP. Compared to other dermal studies, skin samples
used in the Doan et al. ( study were the most relevant and appropriate as they were exposed to a
formulation of 7 percent oil-in-water emulsion, which was preferable over neat chemical. In the ex vivo
experiments, skin was excised from the animals (anatomical site of the tissue collections were not
specified) and radiolabeled DBP (1 mg/m2) was applied to a split thickness skin preparation (200 (j,m)
for 24 or 72 hours. Absorption was measured every 6 hours in a flow-through chamber. The test system
was un-occluded, and skin was washed prior to application. Although certain aspects of the experiment
were not reported, overall, the study complies with OECD Guideline 428 (OECD. 2004b). That study
was given a medium quality rating. A total of 56.3 percent of the administered dose was absorbed; the
percent total recovery was 96.3 percent of the administered dose.
In the in vivo experiment, female hairless guinea pigs were given a single dermal application via covered
patch (3x3 cm2 area; 9 cm2) of an oil-in-water emulsion containing 1 mg/cm2 DBP. The chemical was
applied to the mid-scapular region of the guinea pig back, although it is unclear if this represents 10
percent of the animal body surface. The in vivo dermal absorption of DBP was estimated to be
approximately 62 percent of the applied dose after 24 hours The percent total recovery was 92.9 percent
after 24 hours. Total penetration was reported to be 65.4 percent and included total systemic absorption
plus skin absorption, and recovery of materials in skin around the dosing site, which is in agreement
with the 24-hour ex vivo experiment findings. The outcomes assessment method mostly agreed with
guideline OECD 427 ( ).
2,3,2 Flux-Limited Dermal Absorption for Liquids
Using the Doan (2010) estimate of 56.3 percent absorption of 1 mg/cnr of DBP over 1 day (24 hours),
the steady-state flux of neat DBP is estimated as 2,35/10 2 mg/cm2/h. EPA assumed the steady-state
flux is equal to the average flux.
The DBP estimated steady-state fluxes, based on the results of Doan Q ), are representative of
exposures to liquid materials only. Dermal exposures to liquids containing DBP are described in this
section. Regarding dermal exposures to solids containing DBP, there were no available data and dermal
exposures to solids are modeled as described in Section 2.3.3.
EPA selects Doan et al. (2010) as a representative study for dermal absorption to liquids. Doan et al.
(2010) is a relatively recent (2010) in vivo study in guinea pigs, and it uses a formulation consisting of 7
percent oil-in-water, which is preferred over studies that use neat chemicals. Two other older in vivo
studies were considered: El si si et al. (1989) and Janjua et al. (2008). El si si et al. (1989) provided data on
the dermal absorption of DBP by measuring the percentage of dose excreted in the urine and feces of
rats daily over a 7-day exposure. EPA considers more recent data (2010 vs. 1989) and study duration (24
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hours vs. 7 days) from Doan et al. (2010) to be more appropriate and representative to TSCA dermal
scenarios. The third in vivo study, Janjua et al. (2008). applied cream with a 2 percent DBP formulation
to the skin of human participants daily for 5 days. This study measured the metabolite of DBP—
monobutyl phthalate (MBP)—in urine; however, this study had significant limitations including a very
large inter-individual variability in absorption values and daily variations in values for the same
individual. Two additional ex vivo studies, Scott et al. (1987) and Sugino et al. (2017). noted DBP to be
more readily absorbed in rat skin vs. human skin. Ultimately, EPA prefers the use of in vivo studies
(Doan et al.. 2010) versus ex vivo studies, when available.
2,3.3 Flux-Limited Dermal Absorption for Solids
The dermal absorption of DBP was estimated based on the flux of material rather than percent
absorption. For cases of dermal absorption of DBP from a solid matrix, EPA assumes that DBP first
migrates from the solid matrix to a thin layer of moisture on the skin surface. Therefore, absorption of
DBP from solid matrices is considered limited by aqueous solubility and is estimated using an aqueous
absorption model as described below.
The first step in modeling dermal absorption through aqueous media is to estimate the steady-state
permeability coefficient, Kp (cm/h). EPA utilized the CEM Kp equation (U.S. EPA. 2023) to estimate the
steady-state aqueous permeability coefficient of DBP as 0.017 cm/h. Next, EPA relied on Equation 3.2
from the Risk Assessment Guidance for Superfund (RAGS), Volume I: Human Health Evaluation
Manual, (Part E: Supplemental Guidance for Dermal Risk Assessment) ( 2004). which
characterizes dermal uptake (through and into skin) for aqueous organic compounds. Specifically,
Equation 3.2 from U.S. EPA (2004). also shown in Equation 2-1 below, was used to estimate the
dermally absorbed dose (DAevent, mg/cm2) for an absorption event occurring over a defined duration
(tabs).
Equation 2-1. Dermal Absorption Dose During Absorption Event
16 X tlnr! ^ ^dbs
DAevent = 2xFAxKpxSwx ^ —
Where:
DAevent = Dermally absorbed dose during absorption event tabs (mg/cm2)
FA = Effect of stratum corneum on quantity absorbed = 0.9 (see Exhibit A-5 of
U.S. EPA (2004)) and confirmed by Doan ( ) for 0.87
Kp = Permeability coefficient = 0.017 cm/h (calculated using CEM (
2023))
Sw = Water solubility = 11.2 mg/L [see (U.S. EPA. 2024a)l
tiag = o io5*io00056MW= 0.105*100 0056*27835 = 3.80 hours (calculated from A.4
of U.S. EPA (2004))
tabs = Duration of absorption event (hours)
By dividing the dermally absorbed dose (DAevent) by the duration of absorption (tabs), the resulting
expression yields the average absorptive flux. The dermal consumer exposure assessment scenarios
consider a range of exposure durations that capture low, medium, and high intensity use scenarios and
are described for each COU and product/article scenario in Section 2.3.4. Figure 2-1 illustrates the
relationship between the average absorptive flux and the absorption time for DBP.
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Average Absorptive Flux vs Absorption Time for DBP
1.000
0.900
£ 0.800
§ 0.700
=t 0.600
xl
E 0.500
Ph
P 0.400
& 0.300
o
jq 0.200
0.100 -
0.000 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1
0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Absorption Time (hours)
Figure 2-1. DBP Average Absorptive Flux vs. Absorption Time
Using Equation 3.2 from the Risk Assessment Guidance for Superfund (RAGS), Volume I: Raman
Health Evaluation Manual, (Part E: Supplemental Guidance for Dermal Risk Assessment) (U.S. EPA.
2004) which characterizes dermal uptake (through and into skin) for aqueous organic compounds, EPA
estimated the steady-state flux of DBP to range from 0.89 to 0.18 |ig/cm2/h at 1 to 24 hours. EPA
assumed the steady-state flux is equal to the average flux.
2.3.4 Modeling Inputs and Parameterization
Key parameters for the dermal model include duration of dermal contact, frequency of dermal contact,
total contact area, and dermal flux; an increase in any of these parameters results in an increase in
exposure. Key parameter values used in models are shown in Table 2-9. For contact area, professional
judgment, based on product use descriptions from manufacturers and article typical use, was applied to
determine reasonable contact areas for each product or article. For items that were considered to have a
high level of uncertainty or potential variability, different surface areas were assumed in high, medium,
and low exposure scenarios. In addition to considering typical product and article use, EPA used
conservative contact area options with the possibility of further refining the scenario should risk be
identified in Section 4 of the Draft Risk Evaluation for Dibutyl Phthalate (DBP) (U.S. EPA. 2025d). The
subsections under Table 2-9 provide details on assumptions used to derive other key parameters.
Calculations, sources, input parameters and results are also available in Draft Risk Evaluation for
Dibutyl Phthalate (DBP) - Supplemental Information File: Consumer Exposure Analysis (U.S. EPA.
2025a).
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1272 Table 2-9. Key Parameters Used in Dermal Models
Product
Scenario
Du ration of
Contact
(min)
Frequency of
Contact
(year-1)
Frequency
of Contact
(day-1)
Dermal Flux
(mjj/cm2/hour)
Contact Area
Adhesive for
small repairs
High
60
52
1
2.35E-02
10% of Hands (some fingers)
Med
30
2.35E-02
Low
15
2.35E-02
Adult toys
High
60
365
1
9.23E-04
Inside of one hand (palms,
fingers)
Med
30
1.31E-03
Low
15
1.85E-03
Automotive
adhesives
High
120
2
1
2.35E-02
Inside of two hands (palms,
fingers)
Med
60
2.35E-02
Inside of one hand (palms,
fingers)
Low
30
2.35E-02
10% of Hands (some fingers)
Car mats
High
60
52
1
9.23E-04
10% of Hands (some fingers)
Med
30
1.31E-03
Low
15
1.85E-03
Children's toys
(legacy)
High
137
365
1
6.11E-04
Inside of two hands (palms,
fingers)
Med
88
7.62E-04
Low
24
1.46E-03
Children's toys
(new)
High
137
365
1
6.11E-04
Inside of two hands (palms,
fingers)
Med
88
7.62E-04
Low
24
1.46E-03
Construction
adhesives
High
120
2
1
2.35E-02
Inside of two hands (palms,
fingers)
Med
60
2.35E-02
Inside of one hand (palms,
fingers)
Low
30
2.35E-02
10% of Hands (some fingers)
Footwear
High
480
365
1
3.26E-04
Inside of two hands (palms,
fingers)
Med
240
4.62E-04
Low
120
6.53E-04
Metal coatings
High
120
52
1
2.35E-02
Inside of two hands (palms,
fingers)
Med
60
2.35E-02
Inside of one hand (palms,
fingers)
Low
30
2.35E-02
10% of Hands (some fingers)
Indoor floor
refinishing
products
High
270
4
1
2.35E-02
10% of Hands (some fingers)
Med
180
2.35E-02
Low
90
2.35E-02
Sealing and
refinishing
High
480
2
1
2.35E-02
10% of Hands (some fingers)
Med
240
2.35E-02
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Product
Scenario
Du ration of
Contact
(nrin)
Frequency of
Contact
(year"1)
Frequency
of Contact
(day-1)
Dermal Flux
(mjj/cm2/hour)
Contact Area
sprays
(outdoor use)
Low
120
2.35E-02
Shower
curtains
High
60
365
1
9.23E-04
Inside of one hand (palms,
fingers)
Med
30
1.31E-03
Low
15
1.85E-03
Small articles
with semi
routine contact
High
120
365
1
6.53E-04
Inside of two hands (palms,
fingers)
Med
60
9.23E-04
Inside of one hand (palms,
fingers)
Low
30
1.31E-03
10% of Hands (some fingers)
Spray cleaner
High
30
52
1
2.35E-02
Inside of two hands (palms,
fingers)
Med
15
2.35E-02
Inside of one hand (palms,
fingers)
Low
5
2.35E-02
10% of Hands (some fingers)
Synthetic
leather
clothing
High
480
52
1
3.26E-04
50% of Entire Body Surface
Area
Med
240
4.62E-04
25% of Face, Hands, and Arms
Low
120
6.53E-04
Inside of two hands (palms,
fingers)
Synthetic
leather
furniture
High
480
365
1
3.26E-04
50% of Entire Body Surface
Area
Med
240
4.62E-04
25% of Face, Hands, and Arms
Low
120
6.53E-04
Inside of two hands (palms,
fingers)
Vinyl flooring
High
120
365
1
6.53E-04
Inside of one hand (palms,
fingers)
Med
60
9.23E-04
Low
30
1.31E-03
Wallpaper (in
place)
High
60
365
1
3.26E-04
Inside of one hand (palms,
fingers)
Med
30
4.62E-04
Low
15
6.53E-04
Wallpaper
(installation)
High
480
1
1
3.26E-04
Inside of two hands (palms,
fingers)
Med
240
4.62E-04
Low
120
6.53E-04
Waxes and
polishes
High
60
52
1
2.35E-02
Inside of two hands (palms,
fingers)
Med
30
2.35E-02
Inside of one hand (palms,
fingers)
Low
15
2.35E-02
10% of Hands (some fingers)
1273
1274 Duration of Use/Article Contact Time
1275 For liquid and paste products, it was assumed that contact with the product occurs at the beginning of
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the period of use and the product is not washed off until use is complete. As such, the duration of dermal
contact for these products is equal to the duration of use applied in CEM modeling for products as
described in Section 2.2.3.2. For products not modeled in CEM (concrete adhesive) consumer reviews
indicated that the product was used for outdoor projects of moderate size as well as small repairs. As
such, duration of use was assumed to be 120, 60, and 30 minutes for large, medium, and small projects.
For articles, which do not use duration of use as an input in CEM, professional judgment was used to
select the duration of use/article contact for the low, medium, and high exposure scenario levels. For
flooring products (carpet tiles and vinyl flooring), values for dermal contact time are based on EPA's
Standard Operating Procedures for Residential Pesticide Exposure Assessment for the high exposure
level (2 hour; time spent on floor surfaces) (\ v < < \ IVI J), ConsExpo for the medium exposure level
(1 hour; time a child spends crawling on treated floor), and professional judgment for the low exposure
level (0.5 hour). For articles used in large home DIY projects (wallpaper installation) it was assumed
that a large project could be a full day of work, while smaller projects may be accomplished more
quickly, so contact time for high, medium, and low exposure scenarios were assumed to be 480, 240,
and 120 minutes. Similarly, clothing, footwear, and indoor furniture have the potential for long durations
of dermal contact but may also be used for shorter periods and were thus modeled at 480, 240, and 120
minutes.
For synthetic leather furniture the input parameters in the high intensity use scenario represent either
mostly naked or an underdressed (50% of entire body) person laying or seating on the furniture for 8
hours (480 minutes), which may be an overestimated extreme scenario for all lifestages. The high,
medium, and low intensity use scenario for infants are likely a misuse because infants should not be set
on furniture for extended periods of time; therefore, dermal exposure to infants from synthetic leather
furniture is not expected. EPA has low confidence in using toddler lifestages 8- and 4-hour contact
duration as it may be an extreme consideration and recommends using the low intensity use contact
duration for toddlers. The medium intensity use scenario considers 25 percent of face, hands, and arms
surface in contact with the furniture for 4 hours. The medium intensity use scenario represents a dressed
person either seating or laying on the furniture, which EPA assumes to be a more representative scenario
for preschoolers and older lifestages and the low intensity use scenario contact duration can be used for
toddlers' upper-bound estimate.
For the synthetic leather clothing, EPA assumed that these items would be in contact with the skin for 50
percent of entire body surface area for the high intensity use scenario and 25 percent of face, hands, and
arms for the medium-intensity use scenario. There is uncertainty in assuming large skin contact for
synthetic leather in the high-intensity use scenario. The use of 50 percent of entire body surface equates
to contact with tops and bottom items of clothing. The use of synthetic leather tops and bottoms is
possible; however, EPA is uncertain in the widespread use of these clothing items. The medium-
intensity use scenario for synthetic leather clothing considers 25 percent of face, hands, and arms surface
in contact with the clothing item and for 4 hours total. The medium-intensity use synthetic leather
scenario represents clothing items similar to synthetic leather coats and accessories. EPA has a robust
confidence that the medium-intensity use scenario inputs accurately represent expected uses.
Contact durations of 60, 30, and 15 minutes were assigned to articles anticipated to have low durations
of contact (car mats, shower curtain, and routine [in-place] contact with wallpaper and specialty wall
coverings). To estimate contact time with children's toys, data were obtained from the Children's
Exposure Factors Handbook Table 16-26 (U.S. EPA. (2 . Reported values for playtime for children
under age 15 ranged from 24 min/day to 137 min/day, with a mean value of 88 min/day; these values
were used in the low, high, and medium exposure scenarios. The playtime duration used for children
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under 15 was also used for children 16 to 20 years due to lack of playtime duration information for this
age range, and as a conservative assumption that can be further refined should risk be identified in the
risk characterization stage of this assessment; see Section 4 of th q Draft Risk Evaluation for Dibutyl
Phthalate (DBP) (I. JT \ :_025c).
In addition to the scenarios for dermal exposure to DBP from specific articles, a scenario was modeled
in which consumers may have semi-routine contact with one or more small items containing DBP. A
complete list of articles and associated COUs modeled under this scenario is outlined in Section 2.1.
While dermal contact with these individual items is expected to be short and/or irregular in occurrence,
use of these articles is not well documented, and there is likely to be significant variability in use
patterns between individual consumers. However, given the uncertainty around items with DBP content,
EPA considers it reasonable to assume that an individual could have significant daily contact with some
combination of items and/or with other similar items that have not been measured during monitoring
campaigns. As such, articles modeled under this scenario were assumed to have dermal contact times of
120, 60, and 30 minutes per day.
Frequency of Use
For liquid and paste products modeled in CEM, frequency of contact was assumed to be equal to the
frequency of use (per year and per day) that was applied in CEM modeling. For products used in
potentially large outdoor DIY projects (concrete adhesives), due to significant work required to prepare
and clean-up afterwards it was assumed that these projects were carried out over a 2-day period once per
year.
For articles, assumptions about frequency of use were made using professional judgment, based on one
contact per event duration as a conservative approach. Further refinement is considered at the risk
calculation stage, if necessary (s qq Draft Risk Evaluation for Dibutyl Phthalate (DBP) (
2025c)). For articles that are expected to be used on a routine basis, such as children's toys, furniture,
and shower curtains, use was assumed to be once per day every day. Similarly, for routine contact with
household building materials (carpet tiles, vinyl flooring, and wallpaper), contact was assumed to occur
on a daily basis. For articles used in large home DIY projects (wallpaper installation), due to significant
work required to prepare and clean-up afterwards it was assumed that installation was carried out over a
single day once per year. DBP is expected to be present in PU leather garments. These garments are not
expected to be worn daily but could reasonably be worn on a routine basis. As such, dermal contact with
clothing was modeled as one wear every week. However, children's clothing items reported in the
HPCDS database did not provide adequate descriptive data to draw conclusions about the garment type
or specific component measured. As such, both footwear components and children's clothing were
modeled with daily contact. Car mats were modeled as a single contact event each week, to represent an
individual who does a weekly car cleaning.
2.4 Key Parameters for Intermediate Exposures
The intermediate doses were calculated from the average daily dose (ADD in |ig/kg-day) CEM output
for that product using the same inputs summarized in Table 2-5 for inhalation and Table 2-9 for dermal.
EPA used professional judgment based on manufacturer and online product use descriptions to estimate
events per day and per month for the calculation of the intermediate dose (see Appendix A.3).
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Table 2-10. Short-Term Event per Month and Day Inputs
Product
Events Per Day"
Events Per Month"
Automotive adhesives
1
2
Construction adhesives
1
2
Sealing and refinishing sprays (indoor use)
1
2
Sealing and refinishing sprays (outdoor use)
1
2
a Events per day and month values determined using professional judgment based on
manufacturer product description use.
2.5 Tire Crumb Rubber Modeling
Tire crumb rubber was modeled using a similar approach to a previously published exposure
characterization for the material ( 2024b). This approach models exposure to tire crumb via
inhalation, ingestion, and dermal contact. It was peer reviewed at the time of publication and allows for
an estimate of dose with the limited data available.
The exposure characterization provides concentrations of SVOCs in air samples obtained from both
outdoor (n = 25) and indoor playing fields (n = 15), and a separate document published in conjunction
provided measurements of DBP content in tire particles retrieved from the same locations (
2019c). Concentrations of DBP in air were not reported in the exposure characterization report.
However, DBP concentrations in the tire particles themselves were reported in the associated tire
particle characterization document and were very similar to the reported content of DBP. Physical and
chemical properties expected to significantly impact chemical transport including molecular weight,
octanol air partitioning coefficient, and solubility in water were used to develop estimates for exposure
to DBP during sporting events on tire crumb fields as described below. All calculations are provided in
Draft Consumer Exposure Analysis for Dibutyl Phthalate (DBP) ( 2025a).
2.5.1 Tire Crumb Inhalation Exposure
Air samples were collected for SVOC analysis without a size-selective particle inlet to allow both vapor-
and particle-phase SVOCs to be collected simultaneously. Separate particle- and gas-phase air
concentrations were not measured. However, as previously discussed DBP is more likely to be present
in the particulate rather than gaseous phase. As such, it is unlikely that inhaled DBP will be fully
absorbed after inhalation and the fraction absorbed was estimated to be 0.7. This was the recommended
value in the exposure characterization ( 324b) and likely represents a health-protective
estimate given the slow rate of diffusion through solid media for DBP and low solubility in aqueous
fluids, which would limit partitioning to lung fluids. The inhaled dose per event is defined as:
Equation 2-2. Inhalation Dose Per Exposure Event
Inhalation Event Dose = (Cair x Rinh x ET x ABS)/BW
Where:
Cair
Concentration of DBP in air (mg/m3)
Rinh
Inhalation rate (m3/hour)
ET
Exposure time (hours)
ABS =
Fraction absorbed (0.7)
BW =
Body weight (kg)
Age-stratified inhalation rates during high intensity activity were taken from Exposure Factors
Handbook Table 6-2 (U.S. EPA. 201 I. ). Body weight values were the same as those used in CEM.
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Exposure time was assumed to be 1 hour for children aged less than 11 years, 3 hours for teens 11 to 16
years, and 2 hours for older teens and adults.
2,5,2 Tire Crumb Dermal Exposure
Dermal exposure to tire crumb was assessed under the assumption of dermal adherence during play and
subsequent absorption; the 10th, 50th, and 90th percentile measurements of DBP in tire crumb samples
were used in low, medium, and high exposure scenarios. The fraction of DBP absorbed from each event
was assumed to be 10 percent as recommended in the exposure characterization (U.S. EPA. 2024b). It is
likely that this value somewhat overestimates exposure given that uptake of DBP is expected to be flux
limited. However, a flux-based value could not be calculated as there were no data available to estimate
total contact area of the particulate matter adhered to skin and the assumption of 10 percent absorption is
expected to provide a reasonable, health protective estimate. Dermal dose per exposure event was
defined as follows:
Equation 2-3. Inhalation Dose Per Exposure Event
Dermal Event Dose = (CsoUd x ADH x SAx ABS)/BW
Where:
C solid
Concentration of DBP in crumb rubber (mg/g)
Adh =
Solids adherence on skin (g/cm2 -day)
SA
Skin surface area available for contact (cm2)
ABS =
Fraction absorbed (0.1)
BW =
Body weight (kg)
Age-specific adherence factors were calculated by estimating the percentage of skin surface area
exposed while wearing a typical sports uniform during the summer, multiplying those percentages by
the total surface area per body part found in EPA's Exposure Factors Handbook ( ),
summing the products and then dividing by the total exposed surface area of the body parts to get a
weighted adherence factor (Equation 5-4); this equation can be found in Chapter 7 of the Handbook
(I c. < ^ \ 201 I h). Body part percentages were assumed to be 100 percent of the face, 72.5 percent of
the arms, 40 percent of the legs (to account for socks and short pants), and 100 percent of the hands.
These values were recommended in the exposure characterization based on empirical observations.
Values for dermal adherence to skin were obtained from (Kissel et ai. 1996b). Only values for
adherence of solids to skin after playing sporting events on tire crumb fields was used in this
assessment; the upper and lower boundaries of the 95 percent confidence interval were used in high and
low exposure scenarios, respectively. The geometric mean reported value was used in the medium
exposure scenario.
2.5.3 Tire Crumb Ingestion Exposure
The same values of DBP content in solid particles described in Section 2.5.1 were used to estimate
exposure by inadvertent ingestion during play. The absorption fraction of 50 percent recommended in
the exposure characterization was used ( lb). Ingestion dose per exposure event was then
calculated as follows:
Equation 2-4. Ingestion Dose Per Exposure Event
Ingestion Event Dose = (CsoUd x Ring x ET x ABS)/BW
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Where:
C solid
Concentration of DBP in crumb rubber (mg/g)
Ring
Ingestion rate (g/day)
ET
Exposure time (day)
ABS =
Fraction absorbed (0.5)
BW =
Body weight (kg)
Age-stratified ingestion rates were taken from Exposure Factors Handbook Table 5-1 (
2i ).
2.5,4 Calculation of Acute and Chronic Doses
For all exposure routes, acute and chronic doses were calculated as follows:
Equation 2-5. Chronic Average Daily Dose (CADD)
CADD = (Event Dose x Events x EF)/TA
Where:
EF = Exposure frequency (days/year)
Events = Number of exposure events per day (days-1)
Ta = Averaging time (years)
Equation 2-6. Acute Dose Rate (ADR)
ADR = (Event Dose x Events x EF)/TA
Where:
EF = Exposure frequency (days-1)
Events = Number of exposure events per day (days-1)
Ta = Averaging time (days)
For all exposure scenarios, the number of exposure events per day was assumed to be one. For chronic
dose calculations, the averaging time was assumed to be one year for all scenarios and the exposure
frequency assigned was 78 days per year for children under 11 years, 138 days per year for older
children and teens under 16 years, and 138 days per year for older teens and adults. These values were
recommended in the exposure characterization document based on empirical observations (
2024b).
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3 CONSUMER EXPOSURE MODELING RESULTS
This section summarizes the dose estimates from inhalation, ingestion, and dermal exposure to DBP in
consumer products and articles. Exposure via the inhalation route occurs from inhalation of DBP gas-
phase emissions or when DBP partitions to suspended particulate from installation of solid articles.
Exposure via the dermal route occurs from direct contact with products and articles. Exposure via
ingestion depends on the product or article use patterns. It can occur via direct mouthing {i.e., directly
putting an article in the mouth) or ingestion of suspended and/or settled dust when DBP migrates from a
product or article to dust, or partitions from gas-phase to dust.
3.1 Acute Dose Rate Results, Conclusions and Data Patterns
DBP Draft Consumer Risk Calculator ( 025a) summarizes the high, medium, and low acute
dose rate results from modeling in CEM and outside of CEM (dermal only) for all exposure routes and
all lifestages. Products and articles marked with a dash (-) did not have dose results because the product
or article was not targeted for that lifestage or exposure route. Dose results applicable to bystanders are
highlighted. Bystanders are people that are not in direct use or application of a product but can be
exposed to DBP by proximity to the use of the product via inhalation of gas-phase emissions or
suspended dust. Some product scenarios were assessed for bystanders for children under 10 years and as
users older than 11 years because the products were not targeted for very young children (<10 years). In
instances where a lifestage could reasonably be either a product user or bystander, the user scenarios
inputs were selected as proximity to the product during use would result in larger exposure doses. The
main purpose of DBP Draft Consumer Risk Calculator (U.S. EPA. 2025a) is to summarize acute dose
rate results, show which products or articles did not have a quantitative result, and which results are used
for bystanders. Data patterns are illustrated in figures and descriptions of the patterns by exposure route
and population or lifestage are summarized in this section.
Figure 3-1 through Figure 3-7 show acute dose rate data for all products and articles modeled in all
lifestages assessed. The figures show ADR estimated from exposure via inhalation, ingestion (aggregate
of mouthing, suspended dust ingestion, and settled dust ingestion), and dermal contact. For teens and
adults, dermal contact was a strong driver of exposure to DBP, with the dose received being generally
higher than or similar to the dose received from exposure via inhalation or ingestion. Among the
younger lifestages, this pattern was less clear as these ages were not designated as product users and
therefore not modeled for dermal contact with any of the liquid products assessed. However, dermal
contact was still a strong driver of exposure among young age groups, with doses received from contact
with solid articles generally being roughly equal to or higher than inhalation and ingestion when all were
assessed.
The spread of values estimated for each product or article reflects the aggregate effects of variability and
uncertainty in key modeling parameters for each item; acute dose rate for some products and articles
covers a larger range than others primarily due to a wider distribution of DBP weight fraction values and
behavioral factors such as duration of use or contact time, and mass of product used as described in
Section 2.2. Key differences in exposures among lifestages include designation as product user or
bystander; behavioral differences such as mouthing durations, hand to mouth contact times, and time
spent on the floor; and dermal contact expected from touching specific articles, which may not be
appropriate for some lifestages. Figures and observations specific to each lifestage are below.
Infants, Toddlers, Preschoolers, and Middle Childhood (Birth to 10 Years)
Figure 3-1 shows all exposure routes for infants less than a year old and toddlers 1 to 2 years old, and
Figure 3-2 shows all exposure routes for preschoolers ages 3 to 5 years and middle childhood children
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ages 6 to 10 years. Exposure patterns were very similar for products or articles and routes of exposure
across these four lifestages. Ingestion route acute dose results in these figures show the sum of all
ingestion scenarios, mouthing, suspended dust, and surface dust when applicable for that scenario (see
also Table 2-1).
As previously mentioned, the acute dose values of DBP from exposure to the specific liquid and paste
consumer products assessed here are driven by inhalation exposure only. For solid articles, behavioral
variability was a significant determinant of exposure routes driving exposure. Exposures to articles are
driven primarily by dermal and inhalation, except for vinyl flooring for which the ingestion dose ranges
from medium to high intensity use were higher than dermal. Dermal ADR values are sometimes higher,
for example, furniture textiles, and children's clothing, and in other scenarios inhalation is higher like
vinyl flooring, wallpaper in-place, and legacy children's toys.
Dermal is the highest exposure dose followed by inhalation and then ingestion for products used in small
amounts, such as adhesives and sealants. For articles, dermal doses can be higher than doses from other
routes (e.g., for clothing, carpet tiles, furniture components, shower curtains, and new children's toys) or
lower than doses from inhalation (e.g., vinyl flooring and legacy children's toys). In the case of vinyl
flooring and legacy children's toys, the higher inhalation dose is due to larger DBP weight fractions than
in other articles. Dermal exposure differences among scenarios are driven mainly by the exposure
duration, frequency of the contact, and exposed dermal surface area. Dermal dose values for children's
clothing and furniture textiles were higher mainly because these scenarios used contact durations longer
than the other dermal scenarios. Dermal exposure durations used for furniture textiles and clothing
ranged from 2 to 8 hours per event while for other articles the dermal exposure durations ranged from 2
hours to 15 minutes. In addition, furniture textiles and clothing scenarios used larger surface area of skin
exposed than for other products and articles, like wallpaper, flooring, small articles, footwear that may
have similar contact durations, but less contact skin surface area such as hands, palms, and fingers.
The highest acute dose for these age groups is from inhalation of suspended dust and gas-phase
emissions from vinyl flooring, followed by furniture components, adhesives, children's toys, in-place
wallpaper, carpet tiles, shower curtains, and car mats. Inhalation doses of adhesives and sealants for
these lifestages represent bystander exposures, which is a person in the proximity of someone else using
such products. These products inhalation doses are higher than certain articles, like carpet tiles,
children's toys, and in-place wallpaper, and lower for vinyl flooring and furniture textiles doses. The
differences are driven by DBP weight fractions and total surface area of articles and indoor presence, for
example, vinyl flooring and furniture surfaces are much larger than those covered by toys, shower
curtains, and smaller or less numerous articles, in addition to also having larger weight fractions.
Ingestion of DBP has the overall lowest doses across scenarios, except for vinyl flooring. For articles
assessed for mouthing, such as toys and furniture textiles, exposure from mouthing is expected to have a
larger impact on the overall ingestion dose because it is a direct exposure (see Figure 3-3 and Figure
3-4). Mouthing tendencies decrease or cease entirely for children 6 to 10 years; thus, there is no
contribution to ingestion doses from mouthing for ages above 6 years. Articles not assessed for
mouthing were assessed for ingestion of settled and suspended dust, in which the settled dust exposures
tend to be larger than ingestion from suspended dust.
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Automotive Adhesives
Car Mats
Children's Toys (Legacy)
nhalation
ngestion
Dermal
v Low Exposure Scenario
a Medium Exposure Scenario
X Hign Exposure Scenario
$
$
V
6
A
Children's Toys (New)
V
0
A
Footwear
looring Sealing and Refinishing Products
Metal coatings
ig and Refinishing Sprays (Outdoor Use)
Shower Curtains
small Articles with Semi Routine Contact
Spray cleaner
Synthetic Leather Furniture
$
$
V
0
A
Vinyl Flooring
Wallpaper (In Place)
Waxes and polishes
V o A
-ate
v 0
A
1C
"6 10~5 1(T4 0.001 0.01 0.1
ADR (pg/kg/day) in Infant Users and Bystanders
10 100 1000
1581 Figure 3-1. Acute Dose Rate for DBP from Ingestion, Inhalation, and Dermal Exposure Routes in
1582 Infants (<1 Year) and Toddlers (1-2 Years)
1583 Note: Horizontal axis label is for infants and toddlers. Cutoff labels in order from top to bottom are flooring
1584 sealing and refinishing products, sealing and refmishing sprays (outdoor use), and small articles with potential for
1585 semi-routine contact. Figure will be fixed in fmalization.
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Automotive Adhesives
Car Mats
Children's Toys (Legacy)
Children's Toys (New)
Footwear
looring Sealing and Refinishing Products
Metal coatings
ig and Refinishing Sprays (Outdoor Use)
Shower Curtains
Small Articles with Semi Routine Contact
Spray cleaner
Synthetic Leather Furniture
Vinyl Flooring
Wallpaper (In Place)
Waxes and polishes
nhalation
ngestion
Dermal
Low Exposure Scenario
Medium Exposure Scenario
Hign Exposure Scenario
0 A
0 A
0 a
V 0 a
V 0 A
10"6 10"5 10"4 0.001 0.01 0.1 1 10 100 1000
ADR (jjg/kg/day) in Child Users and Bystanders
n-4
Figure 3-2. Acute Dose Rate of DBP from Ingestion, Inhalation, and Dermal Exposure Routes for
Preschoolers (3-5 Years) and Middle Childhood (6-10 Years)
Note: Horizontal axis label is for preschoolers and middle childhood. Cutoff labels in order from top to bottom are
flooring sealing and refinishing products, sealing and refinishing sprays (outdoor use), and small articles with
potential for semi-routine contact. Figure will be fixed in finalization.
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Car Mats
Children's Toys (Legacy)
Children's Toys (New)
Shower Curtains
Synthetic Leather Furniture
Vinyl Flooring
Wallpaper (In Place)
$
$
V
0
A
Dust (Airborne)
)ust (Settled)
Southing
_ow Exposure Scenario
Medium Exposure Scenari
Hign Exposure Scenario
V o
A
—
v o
A
$
$
<0
A
v 0
A
V c
A
1C
"7 10"6 10"5 1C
"4 0.001 0.01 0.1 1 10 100
ADD (pg/kg/day) for Infant
Figure 3-3. Acute Dose Rate of DBF from Suspended and Settled Dust Ingestion and Mouthing for
Infants (<1 Year)
Car Mats
Children's Toys (Legacy)
Children's Toys (New)
Shower Curtains
Synthetic Leather Furniture
Vinyl Flooring
Wallpaper (In Place)
$
$
Moutning
v Low Exposure Scenario
a Medium Exposure Scenario
X Hign Exposure Scenario
V
0
A
v 0
A
$
$
*0
&
V 0 £
v 0
A
1C
"7 1C
"6 1C
_s 1C
"4 0.001 0.01 0.1
ADD (jjg/kg/day) for Child
10
Figure 3-4. Acute Dose Rate of DBF from Suspended and Settled Dust Ingestion and Mouthing for
Preschoolers (3-5 Years)
Young Teens, Teenagers, Young Adults, and A dults (11-20 Years and 21+ Years)
Figure 3-5 show all exposure routes for young teens (11-15 years) and teenagers and young adults (16-
20 years) combined. Figure 3-6 show all exposure routes for adults above 21 years of age. Exposure
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patterns were very similar for all products and articles and routes of exposure in these three lifestages.
For all of the liquid and paste products assessed, inhalation exposure as a bystander was not assessed for
any of these lifestages as it was deemed reasonable that teenagers, young adults, and adults could all be
users, and the exposure scenario for a user is assumed to be protective of that for a bystander. Users
have higher exposure doses than bystanders due to direct contact with and use of the product. Dermal
exposure resulted in the highest doses overall for both consumable products and solid articles. Inhalation
was also a significant driver of exposure for liquid and paste products. Ingestion was only a significant
source of exposure for these lifestages for the adult toy article, which was modeled for mouthing
exposure. Ingestion via mouthing was not considered for any other articles in these lifestages, as these
lifestages are not expected to engage in mouthing exposure routinely.
The scenarios with higher inhalation doses are driven by larger weight fractions in comparison to other
articles. Ingestion of settled dust is the highest ingestion pathway for products and articles, see Figure
3-7, but dust ingestion was not a significant driver of exposure as compared to inhalation.
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Adhesive for small repairs
Adult Toys
Automotive Adhesives
Dermal
ingestion
nnalation
Low Exposure Scenario
Medium Exposure Scenario
Hign Exposure Scenario
\20R
Car Mats
Children's Toys (Legacy)
Children's Toys (New)
Construction Adhesives
Footwear
looring Sealing and Refinishing Products
Metal coatings
ig and Refinishing Sprays (Outdoor Use)
Shower Curtains
Small Articles with Semi Routine Contact
Spray cleaner
Synthetic Leather Clothing
Synthetic Leather Furniture
Vinyl Flooring
Wallpaper (In Place)
Wallpaper (Installation)
Waxes and polishes
10"6 10"3 10"* 0.001 0.01 0.1 1
ADR (jjg/kg/day) in Teenager Users and Bystanders
1620
1621
1622
1623
1624
1625
v
0 A
V 0 A
v0
V 0 A
saOt,
v 0 a
n-5
n-4
10 100 1000
Figure 3-5. Acute Dose Rate of DBF from Ingestion, Inhalation, and Dermal Exposure Routes for
Young Feens (11—15 Years) and for Feenagers and Young Adults (16-20 Years)
Note: Horizontal axis label is for young teens and teenagers and young adults. Cutoff labels in order from top to
bottom are flooring sealing and refinishing products, sealing and refinishing sprays (outdoor use), and small
articles with potential for semi-routine contact. Figure will be fixed in finalization.
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Adhesive for small repairs
Adult Toys
Automotive Adhesives
Car Mats
Children's Toys (Legacy)
Children's Toys (New)
Construction Adhesives
Footwear
looring Sealing and Refinishing Products
Metal coatings
ig and Refinishing Sprays (Outdoor Use)
Shower Curtains
Small Articles with Semi Routine Contact
Spray cleaner
Synthetic Leather Clothing
Synthetic Leather Furniture
Vinyl Flooring
Wallpaper (In Place)
Wallpaper (Installation)
Waxes and polishes
10"'
V0
10"
Dermal
ngestion
nnalation
Low Exposure Scenario
Medium Exposure Scenario
Hign Exposure Scenario
V
v
0 A
\aCr\
v <> A
10"
0.001 0.01 0.1 1
ADR (|jg/kg/day) in Adult Users and Bystanders
10
100
1000
Figure 3-6. Acute Dose Rate of DBF from Ingestion, Inhalation, and Dermal Exposure Routes in
Adults (21+ Years)
Note: Cutoff labels in order from top to bottom are flooring sealing and refinishing products, sealing and
refinishing sprays (outdoor use), and small articles with potential for semi-routine contact. Figure will be fixed in
finalization.
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Adult Toys
Car Mats
Children's Toys (Legacy)
Children's Toys (New)
Shower Curtains
Synthetic Leather Furniture
Vinyl Flooring
Wallpaper (In Place)
M
H
outhing
ust (Airborne)
ustiSettlea)
)w Exposure Scenario
edium Exposure Scenario
gn Exposure Scenario
.
$
5
V 0 A
V
0 A
$
$
X) A
<7 0 A
V 0
\
1C
"8 1C
"6 1C
"4 0.01
ADD (pg/kg/day) for Teenager
100
Figure 3-7. Acute Dose Rate of DBP from Suspended and Settled Dust Ingestion Exposure Routes
for Young Teens (11-15 Years), Teenagers and Young Adults (16-20 Years), and Adults (21+
Years)
3.2 Intermediate Average Daily Dose Conclusions and Data Patterns
The DBP Draft Consumer Risk Calculator (U.S. EPA. 2025a) summarizes the high- (H), medium- (M),
and low (L)-intensity use intermediate dose results from modeling in CEM and outside of CEM (dermal
calculations and tire crumb exposure all routes) for all exposure routes and all lifestages. Intermediate
exposure durations assess product use in a 30-day period (~1 month). Three product examples were
identified that could reasonably be expected to be used more than once within a 30-day time frame; two
products belonging to the Paints and coatings COU, and one belonging to the Adhesives and sealants
COU. These products were modeled for intermediate exposure scenarios as shown below. Note that
some products do not have dose results for some exposure routes in infants and children because the
product examples were not targeted for that lifestage. However, infants to middle childhood lifestages
are considered bystanders when these products are in use, and thus are exposed via inhalation. Direct
dermal contact has larger doses than inhalation for the users during application of the product (e.g.,
automotive adhesives and flooring sealing and refinishing products). See Figure 3-8 to Figure 3-11 for
intermediate dose visual representation.
Jnhalation
jcjw Exposure Scenario
Medium Exposure Scenario
Hign Exposure Scenario
r6 io'5 ic
r4 o.ooi o.oi o.i l
[Kbrrittididtb ExpLAure Dose (pg/kg/day) in Infant Users and Bysianders
Figure 3-8. Intermediate Dose Rate for DBP from Inhalation Exposure Route in Infants (< Year)
and Toddlers (1-2 Years)
Note: Horizontal axis label is for infants and toddlers. Cutoff labels in order from top to bottom are flooring
sealing and refinishing products and sealing and refinishing sprays (outdoor use). Figure will be fixed in
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Inalization.
Inhalation
v Low Exposure Scenario
a Mediurri Exposure Scepario
• High Exposure Scenario
ng arid Refinishing Sprays (Outdoor Use)
>"6 10'5 1C
I"4 0.001 0.01 0.1 1
[ntCrffludiate Explteijit; Da* (py.'ky.'Cdjr) in Child Useri ariL By&ld'id£r&
Figure 3-9. Intermediate Dose Rate for DBP from Inhalation Exposure Route in Preschoolers (3-5
Years) and Middle Childhood (6-10 Years)
Note: Horizontal axis label is for preschoolers and middle childhood. Cutoff labels in order from top to bottom are flooring
sealing and refinishing products and sealing and refinishing sprays (outdoor use). Figure will be fixed in finalization.
Automotive Adhesives
Construction Adhesives
looring Sealing and Refinishing Products
ig and Refinishing Sprays (Outdoor Use)
10H
¦ Inhalatioi
perms
10"
10"'
0.001
0.01
0.1
10
Intermediate Exposure Dose (pg/kg/day) in Teenager Users and Bystanders
Figure 3-10. Intermediate Dose Rate of DBP from Inhalation and Dermal Exposure Routes for
Young Teens (11-15 Years) and for Teenagers and Young Adults (16-20 Years)
Note: Horizontal axis label is for young teens and teenagers and young adults. Cutoff labels in order from top to
bottom are flooring sealing and refinishing products and sealing and refinishing sprays (outdoor use). Figure will
be fixed in finalization.
Automotive Adhesives
Construction Adhesives
looring Sealing and Refinishing Products
ig and Refinishing Sprays (Outdoor Use)
10"'
10-
¦ Inhalation
Dermal
/ExposureScenario .
0 Exposure Scepano
10
0.001
0.01
0.1
Intermediate Exposure Dose (ug/Vg/day) in Adult Users and Bystarders
10
Figure 3-11. Intermediate Dose Rate of DBP from Inhalation and Dermal Exposure Routes for
Adults (21+ Years)
Note: Cutoff labels in order from top to bottom are flooring sealing and refinishing products and sealing and
refinishing sprays (outdoor use). Figure will be fixed in finalization.
3.3 Non-Cancer Chronic Dose Results, Conclusions and Data Patterns
The DBP Draft Consumer Risk Calculator (U.S. EPA. 2025a) also summarizes the high-, medium-, and
low-intensity use chronic daily dose results from modeling in CEM and outside of CEM (dermal only)
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for all exposure routes and all lifestages. Some products and articles did not have dose results because
the product or article was not targeted for that lifestage or exposure route. Bystanders are people that are
not in direct use or application of the product but can be exposed to DBP by proximity to the use of the
product via inhalation of gas-phase emissions or suspended dust. Some product scenarios (e.g.,
adhesives and sealants) were assessed for bystanders for children under 10 years and as users 11 years or
older because the products were not targeted for use by very young children (<10 years). People older
than 11 years can also be bystanders; however, the user scenarios utilize inputs that would result in
larger exposure doses.
The main purpose of DBP Draft Consumer Risk Calculator ( 325 a) is to summarize chronic
daily dose results, show which products or articles did not have a quantitative result, and which results
are used for bystanders. Data patterns are illustrated in figures in this section, which also includes
summary descriptions of the patterns by exposure route and lifestage. The following set of figures
(Figure 3-12 to Figure 3-15) show chronic average daily dose data for all products and articles modeled
in all lifestages. For each lifestage, figures are provided that show CADD estimated from exposure via
inhalation, ingestion (aggregate of mouthing, suspended dust ingestion, and settled dust ingestion), and
dermal contact. The CADD figures resulted in similar overall data patterns as the acute doses. In
general, exposure was driven largely by dermal exposure for young teens to adults. Ingestion exposures
were generally higher for articles modeled for mouthing in lifestage groups assessed for mouthing
behaviors.
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Car Mats
Ingestion
Dermal
v Low Exposure Scenario
a Medium Exposure Scenario
X High Exposure Scenario
Children's Toys (Legacy)
Children's Toys (New)
Footwear
Metal coatings
Shower Curtains
>mall Articles with Semi Routine Contact
Spray cleaner
Synthetic Leather Furniture
Vinyl Flooring
Wallpaper (In Place)
Waxes and polishes
10
V 0 A
V 0 A
0 A
0 A
0 A
*
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1-6 10"5 10"4 0.001 0.01 0.1 1
CADD (fjg/kg/day) in Infant Users and Bystanders
10
100 1000
Figure 3-12. Chronic Dose Rate for DBP from Ingestion, Inhalation, and Dermal Exposure Routes
in Infants (<1 Year Old) and Toddlers (1-2 Years)
Note: Horizontal axis label is for infants and toddlers. Cutoff label is for small articles with potential for semi-
routine contact. Figure will be fixed in finalization.
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Car Mats
nhalation
ngestion
Dermal
_ow Exposure Scenario
Medium Exposure Scenar
Hign Exposure Scenario
Children's Toys (Legacy)
Children's Toys (New)
Footwear
Metal coatings
Shower Curtains
small Articles with Semi Routine Contact
Spray cleaner
Synthetic Leather Furniture
Vinyl Flooring
Wallpaper (In Place)
Waxes and polishes
0 A
0 A
0 a
V 0 a
V 0 A
n-4
1707
1708
1709
1710
1711
1712
10"6 10"5 10"4 0.001 0.01 0.1 1 10 100 1000
CADD (pg/kg/day) in Child Users and Bystanders
Figure 3-13. Chronic Dose Rate of DBP from Ingestion, Inhalation, and Dermal Exposure Routes
for Preschoolers (3-5 Years) and Middle Childhood (6-10 Years)
Note: Horizontal axis label is for preschoolers and middle childhood. Cutoff label is for small articles with
potential for semi-routine contact. Figure will be fixed in finalization.
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Adhesive for small repairs
Adult Toys
Car Mats
Children's Toys (Legacy)
Children's Toys (New)
Footwear
Metal coatings
Shower Curtains
Small Articles with Semi Routine Contact
Spray cleaner
Synthetic Leather Clothing
Synthetic Leather Furniture
Vinyl Flooring
Wallpaper (In Place)
1713
1714
1715
1716
1717
1718
Dermal
ngestion
nnalation
Low Exposure Scenario
Medium Exposure Scenario
Hign Exposure Scenario
V
v
0 a
v0
v 0 a
v 0 a
Waxes and polishes
10"6 10"5 10"4 0.001 0.01 0.1 1
CADD (jjg/kg/day) in Teenager Users and Bystanders
10 100 1000
Figure 3-14. Chronic Dose Rate of DBP from Ingestion, Inhalation, and Dermal Exposure Routes
for Young Teens (11-15 Years) and for Teenagers and Young Adults (16-20 Years)
Note: Horizontal axis label is for young teens and teenagers and young adults. Cutoff label is for small articles
with potential for semi-routine contact. Figure will be fixed in finalization
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Adhesive for small repairs
Adult Toys
Car Mats
Children's Toys (Legacy)
Children's Toys (New)
Footwear
Metal coatings
Shower Curtains
Small Articles with Semi Routine Contact
Spray cleaner
Synthetic Leather Clothing
Synthetic Leather Furniture
Vinyl Flooring
Wallpaper (In Place)
Waxes and polishes
10
,-6
1719
1720
1721
1722
1723
Dermal
ngestion
nnalation
Low Exposure Scenario
Medium Exposure Scenario
Hign Exposure Scenario
V
v
xgfc.
v0
V o A
0 A
10
i-5
10
i-4
0.001 0.01 0.1 1
CADD (pg/kg/day) in Adult Users and Bystanders
10
100 1000
Figure 3-15. Chronic Dose Rate of DBP from Ingestion, Inhalation, and Dermal Exposure Routes
in Adults (21 + Years)
Note: Cutoff label is for small articles with potential for semi-routine contact. Figure will be fixed in finalization.
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4 INDOOR DUST MODELING AND MONITORING COMPARISON
In this indoor dust exposure assessment, EPA compared modeling and monitoring data. Modeling data
used in this comparison originated from the consumer exposure assessment (Table 2-1) to reconstruct
major indoor sources of DBP in dust and obtain COU and product specific exposure estimates for
ingestion and inhalation of dust. Exposure to DBP via ingestion of dust was assessed for all articles
expected to contribute significantly to dust concentrations due to high surface area (exceeding ~1 m2)
for either a single article or a collection of like articles, as appropriate. These included the following:
• synthetic leather furniture;
• vinyl flooring;
• in-place wallpaper;
• car mats;
• shower curtains;
• children's toys, both legacy and new; and
• tire crumb.
These exposure scenarios were modeled in CEM for inhalation, ingestion of suspended dust, and
ingestion of dust from surfaces. See Section 2.2.3.1 for CEM parameterization, input values, and article
specific scenario assumptions and sources. The DBP Consumer Risk Calculator ( 25a)
summarizes ingestion of settled dust doses used in this comparison. Other non-residential environments
can have these articles, such as daycares, offices, malls, schools, car interiors, and other public indoor
spaces. The indoor consumer articles exposure scenarios were modeled with stay-at-home parameters
that consider use patterns similar to or higher than those in other indoor environments. Therefore, EPA
concludes that the residential assessment represents a health protective upper-bound scenario, which is
inclusive of exposure to similar articles in other indoor environments.
The monitoring data considered are from residential dust samples from U.S. based studies. Measured
DBP concentrations were compared to evaluate consistency among datasets. EPA used ten (10) U.S.
monitoring studies to generate an estimate of overall DBP exposure from ingestion of indoor dust and
performed a monitoring and modeling comparison (Section 0). The monitoring studies and assumptions
made to estimate exposure are described in Section 4.1.
4.1 Indoor Dust Monitoring
The studies not used in the comparison with modeling data measured DBP dust concentrations in non-
residential buildings such as offices, schools, businesses, and day cares, and/or were not conducted in
the United States. Data from other countries were not included in the comparison because of the
expected difference in use patterns, behaviors, and residential characteristics as compared to the U.S.
population. Eighty-eight studies were identified during systematic review as containing measured DBP
concentrations. Of the 88 studies, 11 were identified as containing U.S. data on measured DBP
concentrations in dust in homes, offices, and other indoor environments. Out of the 11 studies, 10 were
selected because they collected settled indoor dust, which is used in the comparison to indoor dust
ingestion modeling data (Section 0). Evaluating the sampled population and sampling methods across
studies was important to determine whether the residential monitoring data were conducted on broadly
representative populations {i.e., not focused on a particular subpopulation).
In Wilson et al. (2001). 10 settled dust samples were collected from U.S. child daycare centers. Five
private, four Head Start (daycare centers), and one back-up center participated. All centers have at least
one classroom with preschool children aged 3 to 5 years. Three centers were in rural communities and
six were in urban centers. Classroom floor dust was collected in the area where the children played the
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In Wilson et al. (2003). four settled dust samples were collected from U.S. child daycare centers and
nine from children's homes. In addition, nine hand wipe samples were taken from children at the
daycares. Classroom and house floor dust were collected in the areas indicated by the teacher or parent
as being where the children played most often. For hand wipe samples, each child's samples were
collected by the child's caregiver. Two wipes for each child were collected at the daycare center, one
just before lunch and before washing the child's hands, on each of the two sampling days. Two
additional wipes were collected at home, just before dinner and before washing the child's hands, on
each of the two sampling days.
In Rudel et al. (2001). six settled dust samples were collected from the United States. One sample was
from an office and five samples were from three different homes in the living areas, attic, and basement.
The study does not report the year of the samples taken. Sample collection was taken by slowly and
lightly drawing the crevice tool just above the surface of rugs, upholstery, wood floors, windowsills,
ceiling fans, and furniture in each room.
In Guo and Kantian (2011). 33 settled dust samples were collected from Albany, New York, between
December 2007 and January 2008, as well as during May 2010. Samples contained particles from carpet
flooring and were taken by vacuum cleaner bags of several homes.
In Dodson et al. (2015). 49 settled dust samples were collected from homes in California during 2006.
Dust samples were collected by slowly dragging the crevice tool just above the surface of rugs,
upholstery, wood floors, windowsills, ceiling fans, and furniture in the primary living areas of the home
for approximately 30 minutes.
In Bi et al. , 43 settled dust samples were collected from multiple indoor environments in
Delaware during 2013. These included 7 apartments, 3 gyms, 4 commercial stores, 5 college student
dormitories, 7 offices, 3 house garages, 10 houses, and 5 daycare centers.
In Bi et al. , 92 settled dust samples were collected from homes in Texas during 2014 and 2015.
For settled dust, a modified vacuum cleaner was used, which was connected to a special aluminum
nozzle holder to avoid contact between dust and plastic parts and limit potential contamination. Dust
sampling was conducted mainly in children's rooms. Dust was collected from the floor surface and from
objects within 30 cm above the floor.
Hammel et al. C measured DBP concentrations in residential dust and was not focused on a
subpopulation. This study collected paired house dust, hand wipe, and urine samples from 203 children
aged 3 to 6 years from 190 households in Durham, North Carolina, between 2014 and 2016, and
additionally analyzed product use and presence of materials in the house. The households were
participants in the Newborn Epigenetics Study (NEST), a prospective pregnancy cohort study that was
conducted between 2005 and 2011. Participants were recontacted and invited to participate in a follow-
up study on phthalate and SVOC exposure, which was titled the Toddlers' Exposure to SVOCs in the
Indoor Environment (TESIE) Study. That study involved home visits conducted between 2014 and
2016.
Table 4-1 reports summary statistics for DBP content in dust from indoor environments. EPA compiled
data from multiple indoor environments such as homes, retail, offices, daycares, and gyms. The studies
reported various indoor environments, see Table 4-1. Statistics (e.g., mean, median, etc.) were directly
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taken from each study, and when individual data were provided EPA calculated the summary statistics.
Sampling methods that used wipes and vacuums to collect samples from surfaces were categorized as
settled dust and were used in the assessment of dust ingestion route in the monitoring indoor dust
exposure assessment. Combined indoor environments mean and medians tend to be higher than
individual environments.
Table 4-1. Detection and Quantification of DBP in House Dust from Various Studies
Study
Indoor
Environment
N
Central
Tendency (jig/g)
Min
fag/g)
Max
fag/g)
SD
(jug/g)
95th
Percentile
(Aig/g)
Detection
Frequency
(%)
Mean
Median
wi[son ct al. (zuui)
Daycare Center
15
18.4
NR
1.58
46.3
NR
NR
NR
Wilson et al (2003)
Home
9
1.21 fl
NR
0.384
3.03
NR
NR
NR
Daycare Center
4
1.87
NR
0.058
5.85
NR
NR
NR
Rude I et al. (2001)
Combined h
6
27.4
NR
11.1
59.4
17.2
NR
100
Griio and Kannan
Q
Home
33
NR
13.1 fl
4.5
94.5
NR
NR
100
Dodson et al. (2015)
Home
49
NR
11 fl
NR
56
NR
35 fl
98
Bi et al. (2015)
Combined h
43
255
27
5
2,300
574
NR
100
Apartment
7
36
12 a
9.2
99
36
NR
100
Home
10
43
24 a
5.4
43
59
NR
100
Home Garage
3
6.3
6.3
4.4
7.3
1.3
NR
100
Student
Dormitory
5
829
360
110
2,151
886
NR
100
Gym
3
45
31
17
87
37
NR
100
Office
7
786
110
17
2,300
963
NR
100
Commercial
Stores
4
22
20
5
42
16
NR
100
Daycare Center
5
77
20
8.8
321
137
NR
100
Bi et al. (2018)
Home
92
115 fl
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4.2 Indoor Dust Monitoring Approach and Results
To estimate DBP dust ingestion, the central tendency ingestion weighted average dose is first calculated
from the reported means and medians of measured concentrations for residential samples (homes and
apartments) in Table 4-1 (see footnote a). Studies that did not report means were not used in the
calculation—only residential settled dust concentration values were used to compare to modeling results
(Section 0). The same equation was used to calculate the high-end value using the reported maximums
and 95th percentile. The central tendency ingestion weighted average concentration is calculated using
Equation 4-1.
Equation 4-1. Ingestion Weighted Average Concentration Calculation
DBP Ingestion Weighted Average (jig/g DBP)
Mean Ingestion Set 1 (^jj-DBP^ x Number in Set 1... + Mean Ingestion Set N (^j-DBP^J x Number in Set N
Number in Set 1... + Number in Set N
EPA used recent U.S. sources for dust ingestion rate and body weights from Ozkavnak et al. (2022). In
their study, Ozkavnak et al. (2022) parameterized the Stochastic Human Exposure Dose Simulation
(SHEDS) Model to estimate dust and soil ingestion for children ages 0 to 21 years with U.S. data,
including the Consolidated Human Activity Database (CHAD) diaries. This most recent version
incorporates new data for young children including pacifier and blanket use, which is important because
dust and soil ingestion is higher in young children relative to older children and adults due to pacifier
and blanket use, increased hand-to-surface contact, and increased rates of hand-to-mouth activity.
Geometric mean and 95th percentile dust ingestion rates for ages 0 to 21 years were taken from
Ozkavnak et al. (2022) to estimate DBP ingestion doses in dust (Table 4-2). The geometric mean (GM)
was used as the measure of central tendency because the distribution of doses is skewed as dust
ingestion doses in young children (3 months to 2 years) are higher vs. older children and adults.
Body weights representative of the U.S. population were taken from Table 8-1 in the Exposure Factors
Handbook (U.S. EPA. ^ ). DBP ingestion was calculated according to Equation 4-2 for two
scenarios: central tendency (geometric mean (GM) dust ingestion, median DBP concentration in dust)
and high-end (dust ingestion, 95th percentile DBP concentration in dust).
Equation 4-2. Calculation of DBP Settled Dust Ingestion Dose
fmg dust\ n /ug DBP\
(hi drd \ Dust inqestion —^ x Dust concentration
™DBP ) = \-*23Ll x
kg bw x day) kg bw 1000 mg
Ozkavnak et al. (2022) did not estimate dust ingestion rates for ages exceeding 21 years. However, the
Exposure Factors Handbook does not differentiate dust or soil ingestion beyond 12 years (
2017). Therefore, ingestion rates for 16 to 21 years, the highest age range estimated in Ozkavnak et al.
(2022). were used for ages beyond 21 years. Using body weight estimates from the Handbook, estimates
were calculated for DBP ingestion dose for 21 to exceeding 80 years (Table 4-3).
Estimates of DBP ingestion in indoor dust per day based on monitoring data are presented in Table 4-2
and Table 4-3.
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1879 Table 4-2. Estimates of DBP Settled Dust Ingestion Per Day from Monitoring, Ages 0-21 Years
Age Range
0 to <1
Months
1 to <3
Months
3 to <6
Months
6 Months
to <1 Year
1 to <2
Years
2 to <3
Years
3 to <6
Years
6 to <11
Years
11 to <16
Year
16 to <21
Years
Dust ingestion
(mg/day) fl
Geometric mean
19
21
23
26
23
14
15
13
8.8
3.5
95th Percentile
103
116
112
133
119
83
94
87
78
46
Body weight (kg) b
4.8
5.9
7.4
9.2
11.4
13.8
18.6
31.8
56.8
71.6
DBP Ingestion
(Hg/kg-day)
Central tendency
(38.8fj.g DBP/g dust)
1.5E-01
1.4E-01
1.2E-01
1.1E-01
7.8E-02
3.9E-02
3.1E-02
1.6E-02
6.0E-03
1.9E-03
High-end
(64.8 (ig DBP/g dust)
2.6E-01
2.3E-01
2.0E-01
1.8E-01
1.3E-01
6.6E-02
5.2E-02
2.6E-02
1.0E-02
3.2E-03
"From Ozkavnak et al. (2022)
b From U.S. EPA (2011b)
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Table 4-3. Estimates of DBP Settled Dust Ingestion Per Day from Monitoring, Ages 21-80+ Years
Age Range
21 to <30
Years
30 to <40
Years
40 to <50
Years
50 to <60
Years
60 to <70
Years
70 to <80
Years
80+ Years
Dust ingestion
(mg/day) fl
Geometric mean
3.5
3.5
3.5
3.5
3.5
3.5
3.5
95th percentile
46
46
46
46
46
46
46
Body weight (kg) b
78.4
80.8
83.6
83.4
82.6
76.4
68.5
DBP ingestion
(Hg/kg-day)
Central tendency
(38.8 (ig DBP/g dust)
1.7E-03
1.7E-03
1.6E-03
1.6E-03
1.6E-03
1.8E-03
2.0E-03
High-end
(64.8 (ig DBP/g dust)
2.9E-03
2.8E-03
2.7E-03
2.7E-03
2.7E-03
3.0E-03
3.3E-03
a From Ozkavnak et al. (2022) (rates for 16-21 years)
b From U.S. EPA (20J
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4.3 Indoor Dust Comparison Between Monitoring and Modeling Ingestion
Exposure Estimates
The exposure dose estimates for indoor dust from the CEM model are larger than those indicated by the
monitoring approach, with the exception of the infant and toddler lifestages. Table 4-4 compares the
sum of the chronic dose central tendency for indoor dust ingestion from CEM outputs for all COUs to
the central tendency predicted daily dose from the monitoring approach. EPA only considered modeling
TSCA COU related articles that are present in residences and homes for comparison with monitoring
data. Car mats and tire crumb rubber are present in indoor environments like vehicles but are not used in
homes and hence inclusion would not be appropriate in this comparison analysis.
Table 4-4. Comparison I
between Modeled and Monitored Daily Dust Intake
Estimates for DBP
Lifestage
Daily DBP Intake
Estimate from Dust,
fig/kg-day,
Modeled Exposure"
Daily DBP Intake Estimate
from Dust,
fig/kg-day,
Monitoring Exposure b
Margin of Error
(Modeled
Monitoring)
Infant (<1 year)
0.047
0.13 c
0.36
Toddler (1-2 years)
0.058
0.078
0.75
Preschooler (3-5 years)
0.066
0.035
1.9
Middle Childhood (6-10
years)
0.023
0.016
1.5
Young Teen (11-15 years)
0.013
0.0060
2.2
Teenager (16-20 years)
0.010
0.0019
5.4
Adult (21+years)
0.0046
0.0017 d
2.7
" Sum of chronic doses for indoor dust ingestion for the "medium" intake scenario for all COUs modeled in CEM
b Central tendency estimate of daily dose for indoor dust ingestion from monitoring data
c Weighted average by month of monitored lifestages from birth to 12 months
J Weighted average by year of monitored lifestages from 21-80 years
The sum of DBP doses from dust in CEM modeled scenarios were higher than those predicted by the
monitoring approach for preschoolers to adults, see Table 4-4. These discrepancies partially stem from
differences in the exposure assumptions of the CEM model vs. the assumptions made when estimating
daily dust doses in Ozkavnak et al. (2022). Dust doses in Ozkavnak et al. (2022) decline rapidly as a
person ages due to behavioral factors including walking upright instead of crawling, cessation of
exploratory mouthing behavior, and a decline in hand-to-mouth events. This age-mediated decline in
dust dose, which is more rapid for the Ozkavnak et al. (2022) study than in CEM, partially explains why
the margin of error between the modeled and monitoring results grows larger with age. Another source
of the margin between the two approaches is the assumption that the sum of the indoor dust sources in
the CEM modeled scenario is representative of items found in typical indoor residences. It is likely that
individual residences have varying assortments and amounts of the products and articles that are sources
of DBP, resulting in lower and higher exposures. The modeling scenario with the largest relative
contribution, 99 percent, to the total modeling aggregate is vinyl flooring. This modeling scenario may
be using a larger surface area presence than the actual in U.S. homes and other indoor environments. In
addition, because the monitoring data is an aggregate of all indoor TSCA and non-TSCA sources of
DBP in dust, a comparison with TSCA-only sources modeling results is challenging.
In the indoor dust modeling assessment, EPA reconstructed the scenario using consumer articles as the
source of DBP in dust. CEM modeling parameters and inputs for dust ingestion can partially explain the
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1915 differences between modeling and monitoring estimates. For example, surface area, indoor environment
1916 volume, and ingestion rates by lifestage were selected to represent common use patterns. CEM
1917 calculates DBP concentration in small particles (respirable particles) and large particles (dust) that are
1918 settled on the floor or surfaces. The model assumes these particles bound to DBP are available via
1919 incidental dust ingestion and estimates exposure based on a daily dust ingestion rate and a fraction of the
1920 day that is spent in the zone with the DBP-containing dust. The use of a weighted dust concentration can
1921 also introduce discrepancies between monitoring and modeling results. Additionally, the scenario that is
1922 mainly driving the large difference is vinyl flooring that may overestimate surface area presence in
1923 indoor environments.
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5 WEIGHT OF SCIENTIFIC EVIDENCE
5.1 Consumer Exposure Analysis Weight of the Scientific Evidence
This section describes the sources of variability and uncertainty, the strengths and weaknesses, and the
overall confidence in the modeled consumer and indoor dust exposure analysis. Variability refers to the
inherent heterogeneity or diversity of data in an assessment. It is a description of the range or spread of a
set of values. Uncertainty refers to a lack of data or an incomplete understanding of the context of the
risk evaluation decision. Variability cannot be reduced, but it can be better characterized while
uncertainty can be reduced by collecting more or better data. Uncertainty is addressed qualitatively by
including a discussion of factors such as data gaps and subjective decisions or instances where
professional judgment was used. Uncertainties associated with approaches and data used in the
evaluation of consumer exposures are described below.
The exposure assessment of chemicals from consumer products and articles has inherent challenges due
to many sources of uncertainty in the analysis, including variations in product formulation, patterns of
consumer use, frequency, duration, and application methods. Variability in environmental conditions
may also alter physical and/or chemical behavior of the product or article. Key sources of uncertainty for
evaluating exposure to DBP in consumer goods and strategies to address those uncertainties are
described in this section.
Generally, designation of robust confidence suggests thorough understanding of the scientific evidence
and uncertainties. The supporting weight of the scientific evidence outweighs the uncertainties to the
point where it is unlikely that the uncertainties could have a significant effect on the exposure estimate.
The designation of moderate confidence suggests some understanding of the scientific evidence and
uncertainties. More specifically, the supporting scientific evidence weighed against the uncertainties is
reasonably adequate to characterize exposure estimates. The designation of slight confidence is assigned
when the weight of the scientific evidence may not be adequate to characterize the scenario, and when
the assessor is making the best scientific assessment possible in the absence of complete information and
there are additional uncertainties that may need to be considered. Table 5-1 summarizes the overall
uncertainty per COU, and a discussion of rationale used to assign the overall uncertainty. The
subsections ahead of the table describe sources of uncertainty for several parameters used in consumer
exposure modeling that apply across COUs and provide an in depth understanding of sources of
uncertainty and limitations and strengths within the analysis. The confidence to use the results for risk
characterization ranges from moderate to robust (Table 5-1). The basis for the moderate to robust
confidence in the overall exposure estimates is a balance between using parameters that represent
various populations, use patterns, and lean on protective assumptions that are not outliers, excessive, or
unreasonable.
Product Formulation and Composition
Variability in the formulation of consumer products, including changes in ingredients, concentrations,
and chemical forms, can introduce uncertainty in exposure assessments. In addition, data were
sometimes limited for weight fractions of DBP in consumer goods. EPA obtained DBP weight fractions
in various products and articles from material SDSs, databases, and existing literature (Section 2.1). A
significant number of DBP concentration in consumer goods data values were published across several
studies published by the Danish EPA. EPA used the Danish EPA information under the assumption that
the weight fractions reported by the Danish EPA are representative of DBP content that could be present
in items sold in the United States. Where possible, EPA obtained multiple values for weight fractions for
similar products or articles. The lowest value was used in the low exposure scenario, the highest value in
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the high exposure scenario, and the average of all values in the medium exposure scenario. EPA
decreased uncertainty in exposure and subsequent risk estimates in the high, medium, and low intensity
use scenarios by capturing the weight fraction variability and obtaining a better characterization of the
varying composition of products and articles within one COU. Overall weight fraction confidence is
moderate for products/articles with multiple sources but insufficient description on how the
concentrations were obtained, robust for products/articles with more than one source, and slight for
articles with only one source with unconfirmed content or little understanding on how the information
was produced.
Product Use Patterns
Consumer use patterns such as frequency of use, duration of use, method of application, and skin contact
area are expected to differ. Where possible, high, medium, and low default values from CEM 3.2's
prepopulated scenarios were selected for mass of product used, duration of use, and frequency of use. In
instances where no prepopulated scenario was appropriate for a specific product, low, medium, and high
values for each of these parameters were estimated based on the manufacturers' product descriptions.
EPA decreased uncertainty by selecting use pattern inputs that represent product and article use
descriptions and furthermore capture the range of possible use patterns in the high- to low-intensity use
scenarios. Exposure and risk estimates are considered representative of product use patterns and well
characterized. Most use patterns overall confidence is rated robust.
Article Use Patterns
For articles inhalation and ingestion exposures the high, medium, and low intensity use scenarios default
values from CEM 3.2's prepopulated scenarios were selected for indoor use environment/room volume,
interzone ventilation, and surface layer thickness. For articles dermal exposures use patterns such as
duration and frequency of use and skin contact area are expected to have a range of low to high use
intensities. For articles that do not use duration of use as an input in CEM, professional judgment was
used to select the duration of use/article contact duration for the low, medium, and high exposure
scenario levels for most articles except for carpet tiles and vinyl flooring. Carpet tiles and vinyl flooring
contact duration values were taken from EPA's Standard Operating Procedures for Residential Pesticide
Exposure Assessment for the high exposure level (2 hours = time spent on floor surfaces) (U.S. EPA.
2012). ConsExpo (U.S. EPA. ^ ) for the medium exposure level (1 hour = time a child spends
crawling on treated floor), and professional judgment for the low exposure level (0.5 hour). Because
there are additional uncertainties in the assumptions and professional judgment for contact duration
inputs for articles, EPA has moderate confidence in those inputs.
Article Surface Area
The surface area of an article directly affects the potential for DBP emissions to the environment. For
each article modeled for inhalation exposure, low, medium, and high estimates for surface area were
calculated (Section 2.1). This approach relied on manufacturer-provided dimensions where possible, or
values from the Exposure Factors Handbook (U. c< « \ 1 I h) for floor and wall coverings. For small
items that might be expected to be present in a home in significant quantities, such as children's toys,
aggregate values were calculated for the cumulative surface area for each type of article in the indoor
environment. Overall confidence in surface area is robust for articles like furniture, wall coverings,
flooring, toys, and shower curtains because there is a good understanding of the presence and
dimensions of these articles in indoor environments.
Human Behavior
CEM 3.2 has three different activity patterns: stay-at-home, part-time out-of-the home (daycare, school,
or work), and full-time out-of-the-home. The activity patterns were developed based on the
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Consolidated Human Activity Database (CHAD). For all products and articles modeled, the stay-at-
home activity pattern was chosen as it is the most protective assumption.
Mouthing durations are a source of uncertainty in human behavior. The data used in this assessment are
based on a study in which parents observed children (n = 236) ages 1 month to 5 years for 15 minutes
per sessions and 20 sessions in total (Smith andNorris. 2003). There was considerable variability in the
data due to behavioral differences among children of the same lifestage. For instance, while children
aged 6 to 9 months had the highest average mouthing duration for toys at 39 minutes per day, the
minimum duration was 0 minutes and the maximum was 227 minutes per day. The observers noted that
the items mouthed were made of plastic roughly 50 percent of the mouthing time, but this was not
limited to soft plastic items likely to contain significant plasticizer content. In another study, 169
children aged 3 months to 3 years were monitored by trained observers for 12 sessions at 12 minutes
each (Greene. 2002). They reported mean mouthing durations ranging from 0.8 to 1.3 minutes per day
for soft plastic toys and 3.8 to 4.4 minutes per day for other soft plastic objects (except pacifiers). Thus,
it is likely that the mouthing durations used in this assessment provide a health protective estimate for
mouthing of soft plastic items likely to contain DBP. EPA assigned a moderate confidence associated
with the duration of activity for mouthing because the magnitude of the overestimation is not well
characterized. All other human behavior parameters are well understood, or the ranges used capture use
patterns representative of various lifestages, which results in a robust confidence in use patterns.
Inhalation and Ingestion Modeling Tool
Confidence in the model used considers whether the model has been peer reviewed, as well as whether it
is being applied in a manner appropriate to its design and objective. The model used, CEM 3.2, has been
peer reviewed (I ), is publicly available, and has been applied in the manner intended by
estimating exposures associated with uses of household products and/or articles. This also considers the
default values data source(s) such as building and room volumes, interzonal ventilation rates, and air
exchange rates. Overall confidence in the proper use of CEM for consumer exposure modeling is robust.
Dermal Modeling of DBP Exposure for Liquids
Experimental dermal data was identified via the systematic review process to characterize consumer
dermal exposures to liquids or mixtures and formulations containing DBP. Section 2.3.1 provides a
description of the selected study and rationale to use (D ) and Section 2.3.2 summarizes
the approach and dermal absorption values used. The confidence in the dermal exposure to liquid
products model used in this assessment is moderate.
EPA selected Doan et al. Q ) as a representative study for dermal absorption to liquids. Doan et al.
(2010) is a relatively recent (2010) in vivo study in guinea pigs, and it uses a formulation consisting of 7
percent oil-in-water, which is preferred over studies that use neat chemicals. In addition, Doan et al.
(2010) conducted in vivo and ex vivo experiments in female hairless guinea pigs to compare absorption
measurements using the same dose of DBP, which increases confidence in the data used. Though there
is uncertainty regarding the magnitude of the difference between dermal absorption through guinea pigs'
skin vs. human skin for DBP, based on DBP physical and chemical properties (size, solubility), EPA is
confident that the in vivo dermal absorption data using guinea pigs for (Doan et al.. 2010) provides an
upper-bound of dermal absorption of DBP.
Another source of uncertainty regarding the dermal absorption of DBP from products or formulations
stems from the varying concentrations and co-formulants that exist in products or formulations
containing DBP. Dermal contact with products or formulations that have lower concentrations of DBP
may exhibit lower rates of flux since there is less material available for absorption. Conversely, co-
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formulants or materials within the products or formulations may lead to enhanced dermal absorption,
even at lower concentrations, but EPA is unclear of the magnitude of the enhanced dermal absorption.
Therefore, it is uncertain whether the products or formulations containing DBP would result in
decreased or increased dermal absorption.
In summary, for purposes of this risk evaluation, EPA assumes that the absorptive flux of DBP
measured from in vivo guinea pig experiments serves as an upper-bound of potential absorptive flux of
chemical into and through the skin for dermal contact with all liquid products or formulations.
Dermal Modeling of DBP Exposure for Solids
Experimental dermal data were not identified via the systematic review process to estimate dermal
exposures to solid products or articles containing DBP, and thus a modeling approach was used to
estimate exposures (see Section 2.3.3). EPA notes that there is uncertainty with respect to the modeling
of dermal absorption of DBP from solid matrices or articles. Because there were no available data
related to the dermal absorption of DBP from solid matrices or articles, the Agency has assumed that
dermal absorption of DBP from solid objects would be limited by aqueous solubility of DBP. To
determine the maximum steady-state aqueous flux of DBP, EPA utilized CEM (U.S. EPA. 2023) to first
estimate the steady-state aqueous permeability coefficient of DBP. The estimation of the steady-state
aqueous permeability coefficient within CEM ( :023) is based on a quantitative structure-
activity relationship (QSAR) model presented by ten Berge (2009). which considers chemicals with
log(Kow) ranging from -3.70 to 5.49 and molecular weights ranging from 18 to 584.6. The molecular
weight and log(Kow) of DBP falls within the range suggested by ten Berge (2009). Therefore, there is
low to medium uncertainty regarding the accuracy of the QSAR model used to predict the steady-state
aqueous permeability coefficient for DBP. There are some uncertainties on the assumption of migration
from solid to aqueous media to skin, which assumes the aqueous dermal exposure model assumes that
DBP absorbs as a saturated aqueous solution {i.e., concentration of absorption is equal to water
solubility), which would be the maximum concentration of absorption of DBP expected from a solid
material. EPA has moderate confidence in the dermal exposure to solid products or articles modeling
approach.
Ingestion Via Mouthing
The chemical migration rate of DBP was estimated based on data compiled in a review published by the
Danish EPA in 2016 (Dani ) (see Section 2.2.3.1). For chemical migration rates to saliva,
existing data were highly variable both within and between studies; for example, the mild mouthing
intensity ranges from 0.04 to 5.8 |ig/cm2-h with an average of 0.17 |ig/cm2-h and a standard deviation of
1.4 |ig/cm2-h. As such, based on available data for chemical migration rates of DBP to saliva, the range
of values used in this draft assessment (0.17, 24.3, and 48.5 |ig/cm2-h, for the mild, medium, and harsh
intensity, respectively) are considered likely to capture the true value of the parameter depending on
article expected uses. For example, EPA assumes children mouthing practices can be mild, medium, or
harsh for children's toys. While adults' mouthing practices for adult toys are not expected to be harsh.
Harsh mouthing of adult toys can likely result in the breakage or destruction of the article and adults
tend to control the harshness of their mouthing better than infants and toddlers. EPA calculated a high
intensity use of adult toys using harsh mouthing approaches as part of the screening approach and
recognized that this highly conservative result is very unlikely behavior. The Agency did not identify
use pattern information regarding adult toys and most inputs are based on professional judgment
assumptions.
A major limitation of all existing data is that DBP weight fractions for products tested in mouthing
studies skew heavily towards relatively high weight fractions (30-60%) and measurements for weight
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2119 fractions less than 15 percent are very rarely represented in the data set. Thus, it is unclear whether the
2120 migration rate values are applicable to consumer goods with low (<15%) weight fractions of DBP,
2121 whereas rates might be lower than represented by typical or worst-case values determined by existing
2122 data sets.
2123
2124 EPA has a moderate confidence in mouthing estimates due to uncertainties about professional judgment
2125 inputs regarding mouthing durations for adult toys and synthetic leather furniture for children. In
2126 general, the chemical migration rate input parameter has a moderate confidence due to the large
2127 variability in the empirical data used in this assessment and unknown correlation between chemical
2128 migration rate and DBP concentration in articles.
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2129 Table 5-1. Weight of Scientific Evidence Summary Per Consumer CPU
Consumer COU Category
and Subcategory
Weight of Scientific Evidence
Overall
Confidence
Construction, paint, electrical,
and metal products;
Adhesives and sealants
Three different scenarios were assessed under this COU for three product types with differing use patterns:
Adhesives for small repairs, automotive adhesives, and construction adhesives. Adhesives for small repairs and
construction adhesives were assessed for dermal exposures only - due to the small product amount and surface
area used in each application, inhalation and ingestion would have low exposure potential for these two
scenarios. Automotive adhesives were assessed for dermal and inhalation exposures. The overall confidence in
this COU's inhalation exposure estimate is robust because the CEM default parameters represent actual use
patterns and location of use. See Section 2.1.2 for number of products, product examples, and weight fraction
data.
For dermal exposure EPA used a dermal flux-limited approach, which was estimated based on DBP in vivo
dermal absorption in guinea pigs. The flux-limited approach likely results in overestimations due to the
assumption about excess DBP in contact with skin. An overall moderate confidence in dermal assessment of
adhesives was assigned. Uncertainties about the difference between human and guinea pig skin absorption
increase uncertainty and due to increased permeability of guinea pig skin as compared to human skin dermal
absorption estimates likely overestimate exposures. Other parameters such as frequency and duration of use, and
surface area in contact, are well understood and representative, resulting in a moderate overall confidence.
Inhalation -
Robust
Dermal -
Moderate
Construction, paint, electrical,
and metal products; Paints and
coatings
Three different scenarios were assessed under this COU for three product types with differing use patterns: metal
coatings, indoor sealing and refinishing sprays, and outdoor sealing and refinishing sprays. All three scenarios
were assessed for dermal and inhalation exposures. The overall confidence in this COU inhalation exposure
estimate is robust because the CEM default parameters represent actual use patterns and location of use. See
Section 2.1.2 for number of products, product examples, and weight fraction data.
For dermal exposure EPA used a dermal flux-limited approach, which was estimated based on DBP in vivo
dermal absorption in guinea pigs. The flux-limited approach likely results in overestimations due to the
assumption about excess DBP in contact with skin. An overall moderate confidence in dermal assessment of
adhesives was assigned. Uncertainties about the difference between human and guinea pigs skin absorption
increase uncertainty and due to increased permeability of guinea pig skin as compared to human skin dermal
absorption estimates likely overestimate exposures. Other parameters such as frequency and duration of use, and
surface area in contact, are well understood and representative, resulting in an overall confidence of moderate.
Inhalation -
Robust
Dermal -
Moderate
Furnishing, cleaning,
treatment care products;
Fabric, textile, and leather
products
Two different scenarios were assessed under this COU for articles with differing use patterns: synthetic leather
clothing and synthetic leather furniture. Indoor synthetic furniture articles were assessed for all exposure routes
as part of the indoor exposure assessment (i.e., inhalation, ingestion (suspended and settled dust, and mouthing),
and dermal), while synthetic clothing was only assessed for dermal contact since the articles were too small to
result in significant inhalation and ingestion exposures. The overall confidence in the synthetic leather furniture
and clothing COU inhalation exposure estimate is robust because the CEM default parameters are representative
of typical use patterns and location of use. The stay-at-home activity use input parameter is considered a
conservative input that although representative of actual uses for some populations is also believed to result in an
Inhalation -
Robust
Ingestion -
Moderate
Dermal -
Moderate
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Consumer COU Category
and Subcategory
Weight of Scientific Evidence
Overall
Confidence
upper-bound exposure. See Section 2.1.2 for number of products, product examples, and weight fraction data.
The indoor furniture ingestion via mouthing exposure estimate overall confidence is moderate due to
uncertainties in the parameters used for chemical migration to saliva, such as large variability in empirical
migration rate data for harsh, medium, and mild mouthing approaches. Additionally, there are uncertainties from
the unknown correlation between chemical concentration in articles and chemical migration rates, and no
reasonably available data were available to compare and confirm selected rate parameters to better understand
uncertainties.
The dermal absorption estimate assumes that dermal absorption of DBP from solid objects would be limited by
the aqueous solubility of DBP. EPA has moderate confidence in the aspects of the exposure estimate for solid
articles because of the high uncertainty in the assumption of partitioning from solid to liquid, and because
subsequent dermal absorption is not well characterized. Additionally, there are uncertainties associated to the
flux-limited approach which likely results in overestimations due to the assumption about excess DBP in contact
with skin. Other parameters such as frequency and duration of use, and surface area in contact have unknown
uncertainties due to lack of information about use patterns, resulting in an overall confidence of moderate.
Furnishing, cleaning,
treatment/care products; Floor
coverings; Construction and
building materials covering
large surface areas including
stone, plaster, cement, glass,
and ceramic articles; Fabrics,
textiles, and apparel
Two different scenarios were assessed under this COU for articles with differing use patterns: vinyl flooring and
wallpaper. Both scenarios were part of the indoor assessment and evaluated for all exposure routes except
mouthing. The scenarios capture the variability from varying manufacturing formulations in the high, medium,
and low intensity use estimates and the weight fraction ranges reported. The overall confidence in the vinyl
flooring and wallpaper COU inhalation exposure estimate is moderate because the CEM input parameters are
representative, but there are uncertainties in the surface area used and location of use. The stay-at-home activity
use input parameter is considered a conservative input that although representative of actual uses for some
populations is also believed to result in an upper-bound exposure. See Section 2.1.2 for number of products,
product examples, and weight fraction data.
The dermal absorption estimate assumes that dermal absorption of DBP from solid objects would be limited by
the aqueous solubility of DBP. EPA has moderate confidence in the aspects of the exposure estimate for solid
articles because of the high uncertainty in the assumption of partitioning from solid to liquid, and because
subsequent dermal absorption is not well characterized. Additionally, there are uncertainties associated to the
flux-limited approach, which likely results in overestimations due to the assumption about excess DBP in
contact with skin. Other parameters such as frequency and duration of use, and surface area in contact, have
unknown uncertainties due to lack of information about use patterns, resulting in an overall confidence of
moderate.
Inhalation -
Moderate
Ingestion -
Moderate
Dermal -
Moderate
Furnishing, cleaning,
treatment/care products;
Cleaning and furnishing care
products
Two different scenarios were assessed under this COU for two product types with differing use patterns: Spray
clear and waxes and polishes. Both scenarios were assessed for dermal and inhalation exposures. The overall
confidence in this COU inhalation exposure estimate is robust because the CEM default parameters represent
actual use patterns and location of use.
Ingestion -
Moderate
Dermal -
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Consumer COU Category
and Subcategory
Weight of Scientific Evidence
Overall
Confidence
For dermal exposure EPA used a dermal flux approach, which was estimated based on DBP in vivo dermal
absorption in guinea pigs. An overall moderate confidence in dermal assessment of adhesives was assigned.
Uncertainties about the difference between human and guinea pigs skin absorption increase uncertainty. Other
parameters such as frequency and duration of use, and surface area in contact, are well understood and
representative, resulting in an overall confidence of moderate in a health protective estimate.
Moderate
Other uses; Novelty articles
One scenario, adult toys, was assessed for this COU. The scenario was assessed for dermal contact and ingestion
via mouthing exposures. Inhalation exposures were determined to be minimal due to small surface area to
release DBP.
Inhalation and
Dust Ingestion
- Robust
The adult toys ingestion exposure estimate overall confidence is moderate due to uncertainties in the parameters
used for chemical migration to saliva such as large variability in empirical migration rate data for harsh,
medium, and mild mouthing approaches. Additionally, there are uncertainties from the unknown correlation
between chemical concentration in articles and chemical migration rates, and no data were reasonably available
to compare and confirm selected rate parameters to better understand uncertainties. In addition, there are
unknown uncertainties in the use duration input parameters, which were assumed based on professional
judgment. EPA calculated a high intensity use of adult toys using harsh mouthing approaches as part of the
screening approach, however recognizing that this highly conservative use pattern is very unlikely behavior, it is
not to be used to estimate risk. EPA did not identify use pattern information regarding adult toys.
Dermal -
Moderate
The dermal absorption estimate assumes that dermal absorption of DBP from solid objects would be limited by
the aqueous solubility of DBP. EPA has moderate confidence in the aspects of the exposure estimate for solid
articles because of the high uncertainty in the assumption of partitioning from solid to liquid, and because
subsequent dermal absorption is not well characterized. Additionally, there are uncertainties associated to the
flux-limited approach, which likely results in overestimations due to the assumption about excess DBP in
contact with skin. Other parameters such as frequency and duration of use, and surface area in contact have
unknown uncertainties due to lack of information about use patterns, resulting in an overall confidence of
moderate.
Other uses; Automotive
articles
Two different scenarios were assessed under this COU for articles with differing use patterns: car mats and
synthetic leather seats. Both scenarios were part of the indoor assessment and evaluated for all exposure routes
except mouthing. The overall confidence in the inhalation exposure estimate for the car mats and synthetic
leather seats COU is robust because the CEM input parameters are representative. The stay-at-home activity use
input parameter is considered a conservative input that although representative of actual uses for some
populations is also believed to result in an upper-bound exposure. See Section 2.1.2 for number of products,
product examples, and weight fraction data.
The dermal absorption estimate assumes that dermal absorption of DBP from solid objects would be limited by
the aqueous solubility of DBP. EPA has moderate confidence in the aspects of the exposure estimate for solid
Dermal -
Moderate
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Consumer COU Category
and Subcategory
Weight of Scientific Evidence
Overall
Confidence
articles because of the high uncertainty in the assumption of partitioning from solid to liquid, and because
subsequent dermal absorption is not well characterized. Additionally, there are uncertainties associated to the
flux-limited approach, which likely results in overestimations due to the assumption about excess DBP in
contact with skin. Other parameters such as frequency and duration of use, and surface area in contact have
unknown uncertainties due to lack of information about use patterns, resulting in an overall confidence of
moderate.
Other uses; Chemiluminescent
light sticks
One scenario was assessed for this COU, chemiluminescent light sticks. The scenario was assessed for dermal
exposures. Inhalation and ingestion exposures were determined to be minimal due to small surface area to
release DBP.
The dermal absorption estimate assumes that dermal absorption of DBP from solid objects would be limited by
the aqueous solubility of DBP. EPA has moderate confidence in the aspects of the exposure estimate for solid
articles because of the high uncertainty in the assumption of partitioning from solid to liquid, and because
subsequent dermal absorption is not well characterized. Additionally, there are uncertainties associated to the
flux-limited approach, which likely results in overestimations due to the assumption about excess DBP in
contact with skin. Other parameters such as frequency and duration of use, and surface area in contact, have
unknown uncertainties due to lack of information about use patterns, resulting in an overall confidence of
moderate.
Inhalation and
Dust Ingestion
- Robust
Dermal -
Moderate
Packaging, paper, plastic,
hobby products; Packaging
(excluding food packaging),
including rubber articles;
plastic articles (hard); plastic
articles (soft); other articles
with routine direct contact
during normal use, including
rubber articles; plastic articles
(hard)
Three different scenarios were assessed under this COU for three article types with differing use patterns:
footwear, shower curtains, and small articles with semi routine contact (e.g., miscellaneous items including a
pen, pencil case, hobby cutting board, costume jewelry, tape, garden hose, disposable gloves, and plastic
bags/pouches). Footwear and small articles with semi routine contact scenarios were assessed for dermal
exposures only. Shower curtains were assessed for dermal and also part of the indoor assessment and evaluated
for all exposure routes except mouthing. The overall confidence in this COU inhalation exposure estimate is
robust because the CEM input parameters are representative. The stay-at-home activity use input parameter is
considered a conservative input that although representative of actual uses for some populations is also believed
to result in an upper-bound exposure. See Section for number of products, product examples, and weight
fraction data.
The dermal absorption estimate assumes that dermal absorption of DBP from solid objects would be limited by
the aqueous solubility of DBP. EPA has moderate confidence in the aspects of the exposure estimate for solid
articles because of the high uncertainty in the assumption of partitioning from solid to liquid, and because
subsequent dermal absorption is not well characterized. Additionally, there are uncertainties associated to the
flux-limited approach, which likely results in overestimations due to the assumption about excess DBP in
contact with skin. Other parameters such as frequency and duration of use, and surface area in contact, have
unknown uncertainties due to lack of information about use patterns, resulting in an overall confidence of
moderate.
CEM
Inhalation -
Robust
Ingestion,
Tire crumb
Inhalation,
and Dermal -
Moderate
Packaging, paper, plastic,
Four different scenarios were assessed under this COU for various articles with differing use patterns: legacy
Inhalation-
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Consumer COU Category
and Subcategory
Weight of Scientific Evidence
Overall
Confidence
hobby products; Toys,
playground, and sporting
equipment
children's toys, and new children's toys, tire crumb and artificial turf, and a variety of PVC articles with
potential for routine contact. Toys scenarios were included in the indoor assessment for all exposure routes
(inhalation, dust ingestion, mouthing, and dermal) with varying use patterns and inputs. Tire crumb was also part
of the indoor assessment for all exposure routes except mouthing, while articles of routine contact were only
assessed for dermal exposures since they are too small to result in impactful inhalation or ingestion exposures.
The high, medium, and low intensity scenarios capture variability and provide a range of representative use
patterns. The overall confidence in this COU inhalation exposure estimate is robust because a good
understanding of the CEM model parameter inputs and representativeness of actual use patterns and location of
use. The stay-at-home activity use input parameter is considered a conservative input that although
representative of actual uses for some populations is also believed to result in an upper-bound exposure. See
Section 2.1.2 for number of products, product examples, and weight fraction data. Tire crumb inhalation
confidence is moderate due to higher uncertainty in using surrogate chemical air concentrations, while all other
parameters are well understood and representative of use patterns by the various age groups. The overall
confidence in this COU's mouthing and dermal exposure assessment is moderate.
The mouthing parameters used like duration and surface area for infants to children are very well understood,
while older groups have less specific information because mouthing behavior is not expected. The chemical
migration value is DBP specific, and the only sources of uncertainty are related to a large variability in empirical
migration rate data for harsh, medium, and mild mouthing approaches. Additionally, there are uncertainties from
the unknown correlation between chemical concentration in articles and chemical migration rates, and no data
were reasonably available to compare and confirm selected rate parameters to better understand uncertainties.
Dermal absorption estimates are based on the assumption that dermal absorption of DBP from solid objects will
be limited by aqueous solubility of DBP. EPA has moderate confidence for solid objects because the high
uncertainty in the assumption of partitioning from solid to liquid and subsequent dermal absorption is not well
characterized. Additionally, there are uncertainties associated to the flux-limited approach, which likely results
in overestimations due to the assumption about excess DBP in contact with skin. Other parameters like
frequency and duration of use, and surface area in contact have unknown uncertainties due to lack of information
about use patterns, making the overall confidence of moderate.
Robust
Dermal -
Moderate
2130
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5.2 Indoor Dust Monitoring Weight of the Scientific Evidence
The weight of scientific evidence (WOSE) for the indoor dust exposure assessment of DBP (Table 5-2)
is dependent on studies that include indoor residential dust monitoring data (Table 4-4). Studies included
indoor dust samples taken from residences and multiple indoor environments were extracted. In the case
of DBP, three studies were identified as containing data on indoor environment dust in the United States
and were selected for use in the indoor dust monitoring assessment as described in Section 4.1. The
study rating per the exposure systematic review criteria is listed in Table 5-2.
Table 5-2. Weight of the Scientific Evidence Conclusions for Indoor Dust Ingestion Exposure
Studies Used in Monitoring
Indoor Analysis
Systematic
Review Rating
Confidence in
Data Used
Confidence in Model Inputs
Weight of
Scientific
Evidence
Conclusion
Body
Weight"
Dust Ingestion
Rate4
W1 [son ct al. (2UU3 )
Medium
Moderate
Robust
Moderate
Moderate
Griio and Kaniian (2011)
High
Slight
Moderate
Dodson et al. (2015)
Medium
Moderate
Moderate
Bi et al (2015)
High
Robust
Robust
Bi et al. (2018)
High
Moderate
Moderate
Haniniel et al. (2019)
High
Robust
Robust
Shin et al. (2019)
Medium
Moderate
Moderate
"1^! r.x i:oiib)
^Ozkavnak et al. (2022)
Table 5-2 presents the assessor's level of confidence in the data quality of the input datasets for
estimating dust ingestion from monitoring data, including the DBP dust monitoring data themselves, the
estimates of U.S. body weights, and the estimates of dust ingestion rates, according to the following
rubric:
• Robust confidence means the supporting weight of the scientific evidence outweighs the
uncertainties to the point that the assessor has decided that it is unlikely that the uncertainties
could have a significant effect on the exposure estimate.
• Moderate confidence means the supporting scientific evidence weighed against the uncertainties
is reasonably adequate to characterize exposure estimates, but uncertainties could have an effect
on the exposure estimate.
• Slight confidence means the assessor is making the best scientific assessment possible in the
absence of complete information. There may be significant uncertainty in the underlying data
that needs to be considered.
These confidence conclusions were derived from a combination of systematic review {i.e., the quality
determinations for individual studies) and the assessor's professional judgment.
In Wilson et al. (2003) (systematic review rating was medium), monitoring data was collected in
Durham, North Carolina for DBP in children's homes. This study sampled nine homes as well as nine
hand wipe samples. House floor dust samples were collected with a High Volume Small Surface
Sampler (HVS3; Cascade Stack Sampling Systems Inc., Bend, Oregon) in the areas indicated by the
teacher or parent as being where the children played most often. While these samples could be
representative of the general U.S. population, the small sample size and lack of geographic diversity,
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selection of certain types of homes for the children in the study add to the uncertainty. Because of these
uncertainties, EPA has assigned moderate confidence to our use of this model input.
In Guo and Kantian (2011) (systematic review rating was high), monitoring data was collected in
Albany, New York for DBP between 2007 and 2008 for 33 houses. Dust samples were collected by
sweeping the floor and wiping the top of furniture as well as from vacuum cleaner bags of several
homes. Information was not given about the type of housing and if it is representative of the general
U.S. population. Because of this uncertainty, EPA has assigned moderate confidence to our use of this
model input.
In Dodson et al. (2015) (systematic review rating was medium), monitoring data was collected in
Richmond and Bolinas, California for DBP from the California Household Exposure Study (CAHES)
study conducted in 2006. This study sampled 49 nonsmoking homes in a low-income urban community
and a rural community around the San Francisco area. Samples were collected by slowly dragging a
crevice tool just above the surface of rugs, upholstery, wood floors, windowsills, ceiling fans, and
furniture in the primary living areas of the home for approximately 30 minutes. While these samples
collect indoor dust samples from an existing study, the low income and rural population studied might
not be representative of the general U.S. public. Because of this uncertainty, EPA has assigned moderate
confidence to our use of this model input.
In Bi et al. (1 (systematic review rating was high), monitoring data was collected from Dover,
Delaware for DBP in 2013. This study sampled 10 houses, with the floor material being made of carpet,
hardwood or a combination of both. The study also indicated that the houses did not have a custodian for
daily cleaning. Dust samples were collected using a bagged vacuum cleaner through an easily cleaned
suction tube. Before each sampling, the internal surface of the suction tube was cleaned using an animal-
hair brush and a piece of clean cloth, and a new bag was placed for dust collection. EPA believes these
samples may not be a general representation of the U.S. population due to small number of samples and
lack of geographic variability. Because of this, EPA has assigned robust confidence to our use of this
model input.
In Bi et al. (2018) (systematic review rating was high), monitoring data was collected from Texas for
DBP in 2014 and 2015. The study is part of a large project to investigate asthma triggers for children in
low-income homes. A total of 54 homes (92 samples) from rural/semi-rural areas of central Texas
enrolled in this study. Dust sampling was conducted mainly in children's rooms. Dust was collected
from the floor surface and from objects within 30 cm above the floor. While these samples collect
indoor dust samples from homes, the study selected low-income homes for children and is not
representative of the general U.S. public. Because of this uncertainty, EPA has assigned moderate
confidence to our use of this model input.
Monitoring data collected in the United States was identified for DBP from the Toddlers' Exposure to
SVOCs in the Indoor Environment (TESIE) study conducted between 2014 and 2016 (Hammel et al..
2019) (systematic review rating was high). This study sampled 190 residences in Durham, North
Carolina, and included vacuum dust sampling as well as hand wipes and urine samples. Households
were selected from participants in the Newborn Epigenetics Study, which is a prospective pregnancy
cohort that began in 2005 and recruited pregnant women who received services at Duke obstetrics
facilities. Although these facilities are associated with a teaching hospital and university, services are not
restricted to students, and the demographic characteristics of the TIESIE study population match those
of the Durham community (see Table 1 in Ham m el i ). Because this study carefully selected
participants to avoid oversampling subpopulations and investigated a relatively large number of
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residences for a study of this type, and because EPA identified no reason to believe that households in
the study location (Durham, North Carolina) would represent an outlier population that would not
adequately represent the consumer practices of the broader U.S. public, EPA has assigned robust
confidence to our use of this model input.
In Shin e (systematic review rating was medium), monitoring data was collected in Northern
California from 2015 to 2016. This study sampled 38 family homes. From each household, one dust
sample from an approximate 2 m2 area in the main living room using a high-volume small surface
sampler (HVS3) were collected. Since the study does not provide much information about the
households, it is hard to determine if they are representative of the general U.S. public. Because of this
uncertainty, EPA has assigned moderate confidence to our use of this model input.
Body weight data was obtained from the Exposure Factors Handbook ( ). This source is
considered the default for exposure related inputs for EPA risk assessments and is typically used unless
there is a particular reason to seek alternative data. Because the Exposure Factors Handbook is generally
considered the gold standard input for body weight, and because the underlying body weight data were
derived from the U.S. nationally representative NHANES dataset, EPA has assigned robust confidence
to our use of this model input.
Total daily dust intake was obtained from Ozkavnak et al. (2022). This study used a mechanistic
modeling approach to aggregate data from a wide variety of input variables (Table 5-3). These input
variables were derived from several scientific sources as well as from the professional judgment of the
study authors. The dust ingestion rates are similar to those found in the Exposure Factors Handbook
(\ c. i i1 \ JO I I .*) for children under 1 year old but diverge above this age (Table 5-4). The Ozkavnak
et al. (2022) dust ingestion rates are one-half to approximately one-fifth as large, depending on age. This
is because the Handbook rates are a synthesis of several studies in the scientific literature, including
tracer studies that use elemental residues in the body to estimate the ingestion of soil and dust.
According to the discussion presented in Ozkavnak et al. (2022). these tracer studies may be biased
high, and in fact as shown in Figure 4 of Ozkavnak et al. (2022). non-tracer studies align much more
closely with the dust ingestion rates used in this analysis. Because some input variables were unavailable
in the literature and had to be based on professional judgment, and the dust ingestion rates differ from
those in the Handbook, EPA has assigned moderate confidence to this model input.
Taken as a whole, with robust confidence in the DBP concentration monitoring data in indoor residential
dust from Hammel et al. (2019). robust confidence in body weight data from the Exposure Factors
Handbook , and moderate confidence in dust intake data from Ozkavnak et al. (2022).
EPA has assigned a WOSE rating of robust confidence to estimates of daily DBP intake rates from
ingestion of indoor dust in residences.
5.2.1 Assumptions in Estimating Intakes from Indoor Dust Monitoring
5.2.1.1 Assumptions for Monitored DBP Concentrations in Indoor Dust
The DBP concentrations in indoor dust were derived from the seven studies in Table 4-1. Five of the
studies rated moderate and two studies rated robust in confidence in data used. The studies rated
moderate were assumed to not be representative of a typical U.S. household while the robust studies
were assumed to be representative. For some studies, samples were either taken from the living room or
children's room, where the children's room was identified as the room in which the child(ren) residing
in the home spent the most time. A key assumption made in this analysis is that dust concentrations in
playrooms and living rooms are representative of those in the remainder of the home.
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5.2.1.2 Assumptions for Body Weights
Body weights were taken from the Exposure Factors Handbook ( ), in which they were
derived from the NHANES 1999 to 2006 dataset. The NHANES studies were designed to obtain a
nationally representative dataset for the United States and include weight adjustment for oversampling
of certain groups (children, adolescents 12-19 years, persons 60+ years of age, low-income persons,
African Americans, and Mexican Americans). Body weights were aggregated into the age ranges shown
in Table 4-2, Table 4-3, and Table 4-4 and were averaged by sex.
5.2.1.3 Assumptions for Dust Ingestion Rates
To estimate daily intake of DBP in residential indoor dust, a daily rate of dust ingestion is required. EPA
used rates from Ozkavnak et al. (2022). which modeled to estimate dust and soil intakes for children
from birth to 21 years. A probabilistic approach was used in the Ozkavnak et al. (2022) study to assign
exposure parameters including behavioral and biological variables. The exposure parameters are
summarized in Table 5-3 and the statistical distributions chosen are reproduced in detail in the
supplemental material for Ozkavnak et al. (2022).
Table 5-3. Summary of Variables from Ozkavnak et al. 2022 Dust/Soil Tni
take Model
Variable
Description
Units
Sou rcc
Bathdaysmax
Maximum # days between baths/showers
days
Ozkavnak et al. (2011). based
on Kissel 2003 (personal
communication)
Dusthomehard
Dust loading on hard floors
(ig/cm2
Adeate et al. (1995)
Dusthomesoft
Dust loading on carpet
(ig/cm2
Adeate et al. (1995)
Fremovebath
Fraction of loading removed by bath or shower
(-)
Professional judgment
Fremovehandmouth
Fraction of hand loading removed by one
mouthing event
(-)
Kissel et al. (1998) and (Tliibal
et al, 2008)
Fremovehandwash
Fraction of hand loading removed by hand
washing
(-)
Professional judgment
Fremovehour
Fraction of dermal loading removed by passage
of time
(-)
Ozkavnak et al. (2011)
Ftransferdusthands
Fraction of floor dust loading transferred to
hands by contact
(-)
Ozkavnak et al. (2011)
Ftransferobj ectmouth
Fraction transferred from hands to mouth
(-)
Zartarian et al. (2005), based
on Leckie et al. (2000)
Handcontactratio
Ratio of floor area contacted hourly to the hand
surface area
1/h
Freeman et al. (2001) and
Zartarian et al. (1997)
Handloadmax
Maximum combined soil and dust loading on
hands
(ig/cm2
Ozkavnak et al. (2011)
Hand_washes_per_day
Number of times per day the hands are washed
1/day
Zartarian et al. (2005)
Objectfloordustratio
Relative loadings of object and floor dust after
contact
(-)
Professional judgment, based
on Gurunathan et al. (1998)
Phomehard
Probability of being in part of home with hard
floor
(-)
Ozkavnak et al. (2011)
Phomesoft
Probability of being in part of home with carpet
(-)
Ozkavnak et al. (2011)
Adherencesoil"
Accumulated mass of soil that is transferred
onto skin
mg/cm2
Zartarian et al. (2005), based
on Holmes et al. (1999).
Kissel et al. (1996a). and
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Variable
Description
Units
Sou rcc
Kissel et al. (1996b)
Handmouthfraction"
Fraction of hand area of one hand contacting
the inside of the mouth
(-)
Tsou et al. (2017)
Handmouthfreq"
(indoor/outdoor)
Frequency of hand-mouth contacts per hour
while awake - separate rate for indoor/outdoor
behavior
(-)
Black et al. (2005) and Xue et
al. (2007)
Objectmoutharea"
Area of an object inserted into the mouth
cm2
Leckie et al. (2000)
Objectmouthfreq"
Frequency at which objects are moved into the
mouth
(-)
Xue et al. (2010)
Pblanketh
Probability of blanket use
(-)
Professional judgment
Fblanketh
Protective barrier factor of blanket when used
(-)
Professional judgment
Pacifiersize b
Area of pacifier surface
cm2
Ozkavnak et al. (2022)
Pacifierfrachardh
Fraction of pacifier drops onto hard surface
(-)
Professional judgment
Pacifierfracsofth
Fraction of pacifier drops onto soft surface
(-)
Professional judgment
Pacifiertransferh
Fraction of dust transferred from floor to
pacifier
(-)
Extrapolated from Rodes et al.
(2001). Beamer et al. (2009).
and (Hubal et al. 2008)
Pacifierwashingh
Composite of the probability of cleaning the
pacifier after it falls and efficiency of cleaning
(-)
Conservative assumption
(zero cleaning is assumed)
Pacifier drop h
Frequency of pacifier dropping
(-)
Tsou et al. (2015)
P_pacifierb
Probability of pacifier use
(-)
Tsou et al. (2015)
" Variable distributions differ by lifestage
h Variable only applies to children younger than 2 years
5.2.2 Uncertainties in Estimating Intakes from Monitoring Data
5.2.2.1 Uncertainties for Monitored DBP Concentrations in Indoor Dust
For all seven studies, there is uncertainty for sampling biases which can include choice of study location,
include only households that contain children and by differences among the households that chose to
participate in the study. For example, Hammel et al. (2019) sampled residential house dust in 190
households in Durham, North Carolina, from a population selected from an existing pregnancy cohort
study. In addition, differences in consumer behaviors, housing type and quality, tidiness, and other
variables that affect DBP concentrations in household dust are possible between participating
households and the general population.
5.2.2.2 Uncertainties for Body Weights
Body weights were obtained from the Exposure Factors Handbook ( ), which contains
data from the 1999 to 2006 NHANES. Body weights were aggregated across lifestages and averaged by
sex. In general, body weights have increased in the United States since 2006 (CDC. ^ ), which may
lead to an underestimate of body weight in this analysis. This would lead to an overestimate of DBP
dose per unit body weight, because actual body weights in the U.S. population may be larger than those
assumed in this analysis.
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5.2.2.3 Uncertainties for Dust Ingestion Rates
Dust ingestion rates were obtained from Ozkavnak et al. (2022). which uses mechanistic methods (the
SHEDS Model) to estimate dust ingestion using a range of parameters (Table 5-3). Each of these
parameters is subject to uncertainty, especially those that are derived primarily from the professional
judgment of the authors. Because of the wide range of parameters and the lack of comparator data
against which to judge, EPA is unable to determine the direction of potential bias in each of the
parameters individually. For dust ingestion rates overall, the rates derived from Ozkavnak et al. (2022)
can be compared to those found in the Exposure Factors Handbook ( ) (Table 5-4).
Table 5-4. Comparison Between Ozkaynak et al. 2022 and Exposure Factors Handbook Dust
Ingestion Rates
Age Ratine
Oto <1
Month
1 to <3
Months
3 to <6
Months
6 Months
to <1
Year
1 to <2
Years
2 to <3
Years
3 to <6
Years
6 to
<11
Years
11 to
<16
Years
16 to
<21
Years
Central
tendency dust
ingestion
(mg/day)
Ozkavnak et
al. (2022)
19
21
23
26
23
14
15
13
8.8
3.5
U.S. EPA
20
20
20
20
50
30
30
30
20 a
20
" The intake for an 11-year-old based on the Exposure Factors Handbook is 30 mg/day. Not that the age ranges do not
align between the two sources in this instance.
The Ozkaynak et al. (2022) dust intake estimates for children above 1 year old are substantially lower
than those in the Exposure Factors Handbook (U. c< «I1 \ 1 I. ), while the estimate for children
between 1 month and 1 year old are slightly higher. The authors of the Ozkavnak et al. (2022) study
offer some justification for the discrepancy by noting that the Handbook recommendations are a
synthesis of several types of study, including tracer studies that "[suffer] from various sources of
uncertainty that could lead to considerable study-to-study variations." Biokinetic and activity pattern
studies, such as Von Lindern et al. 2016 and Wilson et al. 2013 respectively, achieve results that are
closer to the Ozkavnak et al. (2022) results (see Fig. 4, Ozkavnak et al. (2022).
5.2.2.4 Uncertainties in Interpretation of Monitored DBP Intake Estimates
There are several potential challenges in interpreting available indoor dust monitoring data. The
challenges include the following:
• Samples may have been collected at exposure times or for exposure durations not expected to be
consistent with a presumed hazard based on a specified exposure time or duration.
• Samples may have been collected at a time or location when there were multiple sources of DBP
that included non-TSCA COUs.
• None of the identified monitoring data contained source apportionment information that could be
used to determine the fraction of DBP in dust samples that resulted from a particular TSCA or
non-TSCA COU. Therefore, these monitoring data represent background concentrations of DBP
and are an estimate of aggregate exposure from all residential sources.
• Activity patterns may differ according to demographic categories (e.g., stay at home/work from
home individual vs. an office worker), which can affect exposures especially to articles that
continually emit a chemical of interest.
• Some indoor environments may have more ventilation than others, which may change across
seasons.
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6 CONCLUSION AND STEPS TOWARD RISK
CHARACTERIZATION
Indoor Dust
For the indoor exposure assessment, EPA considered modeling and monitoring data. Monitoring data is
expected to represent aggregate exposure to DBP in dust resulting from all sources present in a home.
Although it is not a good indicator of individual contributions of specific COUs, it provides a real-world
indicator of total exposure through dust. For the modeling assessment of indoor dust exposures and
estimating contribution to dust from individual COUs, EPA re-created indoor environments using
consumer products and articles commonly present in indoor spaces. For example, the indoor assessment
considered inhalation exposure from toys, flooring, synthetic leather furniture, wallpaper, and others
including a consideration of dust collected on the surface of a relatively large area, like flooring,
furniture, and wallpaper, but also multiple toys and wires collecting dust with DBP and subsequent
inhalation and ingestion.
While there are differences between modeled and monitoring indoor dust assessment estimates, EPA
considers the differences minor and a way to confirm the approaches used in the modeling and
monitoring indoor dust assessment. The monitoring estimates were used as a comparator to show that
the modeled DBP exposure estimates were health protective relative to residential monitored exposures
(Table 4-4). This comparison was a key input to our robust confidence in the overall health
protectiveness of our exposure assessment for ingestion of DBP in indoor dust. The individual COU
scenarios had a moderate to robust confidence in the exposure dose results and protectiveness of
parameters used. Thus, the COU scenarios of the articles used in the indoor assessment were utilized in
risk estimates calculations.
Consumer
All COU exposure dose results summarized in Section 3 and the DBP Draft Consumer Risk Calculator
(I 5a) have a moderate to robust confidence and hence can be used for risk estimate
calculations and to determine risk to the various lifestages. The consumer assessment has low, medium,
and high exposure scenarios that represent use patterns of high-, medium-, and low-intensity uses. The
high exposure scenarios capture use patterns for high exposure potential from high frequency and
duration use patterns, extensive mouthing behaviors, and conditions that promote greater migration of
DBP from products/articles to sweat and skin. Low and medium exposure scenarios represent less
intensity in use patterns, mouthing behaviors, and conditions that promote DBP migration to sweat and
skin, capturing populations with different lifestyles.
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diisobutyl phthalate (DIBP). Copenhagen, Denmark: Danish Environmental Protection Agency ::
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activity data for children aged 7 to 35 months in Taiwan. J Expo Sci Environ Epidemiol 25: 388-
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Tsou. MC; Ozkaynak. H; Bearner. ig. W; Hsi. HC; Jiang. CB; Chien. LC. (2017). Mouthing
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http://dx.doi.ore 38/ies.2016.87
U.S. EPA. (2004). Risk Assessment Guidance for Superfund (RAGS), volume I: Human health
evaluation manual, (part E: Supplemental guidance for dermal risk assessment).
(EPA/540/R/99/005). Washington, DC: U.S. Environmental Protection Agency, Risk
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https://www.epa.gov/expobox/exposure-factors-handbook-chapter-6
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[EPA Report], (EPA/600R-17/384F). Washington, DC: National Center for Environmental
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Appendix A ACUTE, CHRONIC, AND INTERMEDIATE DOSE
RATE EQUATIONS
The equations provided in this section were taken from the
A.l Acute Dose Rate
Acute dose rate for inhalation ofproduct used in an environment (CEM PINHl Model), such as
indoor, outdoor, living room, garage, kitchen, bathroom, office, etc. was calculated as follows:
EquationApx A-l. Acute Dose Rate for Inhalation of Product Used in an Environment
Cair x Inh x FQ x Dac x ED
ADR ~ BW x AT x CF1
Where:
ADR =
Acute Dose Rate (mg/kg-day)
C ¦ =
uair
Concentration of DBP in air (mg/m3)
Inh =
Inhalation rate (m3/h)
FQ =
Frequency of product use (events/day)
Dac =
Duration of use (min/event), acute
ED
Exposure duration (days of product usage)
BW =
Body weight (kg)
AT
Averaging time (days)
CFi =
Conversion factor (60 min/h)
For the ADR calculations, an averaging time of 1 day is used. The airborne concentration in the above
equation is calculated using the high-end consumer product weight fraction, duration of use, and mass of
product used. Therefore, in this case, the ADR represents the maximum time-integrated dose over a 24-
hour period during the exposure event. CEM calculates ADRs for each possible 24-hour period over the
60-day modeling period (i.e., averaging of hours 1-24, 2-25, etc.) and then reports the highest of these
computed values as the ADR.
Acute dose rate for inhalation from article placed in environment (CEM AINHl Model) was calculated
as follows, where the term environment refers to any indoor and outdoor location, such as garage,
kitchen, bathroom, living room, car interior, daycare, school room, office, backyard and so on:
Equation Apx A-2. Acute Dose Rate for Inhalation from Article Placed in Environment
Cgas max x FracTime x InhalAfter x CF1
ADRAir = = BW x CF2
Equation Apx A-3. Acute Dose Rate for Particle Inhalation from Article Placed in Environment
DBP RPair max x RPair_ avg x FracTime x InhalAfter x CFX
ADR particulate ~ dt/ia w n n
BW X Ct7
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EquationApx A-4. Total Acute Dose Rate for Inhalation of Particulate and Air
ADRtgtdi — ADRAir + ADRpartiCUiate
Where:
ADRAir
AD Rp articulate
ADRtotal
r
ugasjnax
DBPRPnir rnnv
RPairjnax
FracTime
InhalAfter
CFi
BW
cf2
Acute Dose Rate, air (mg/kg-day)
Acute Dose Rate, particulate (mg/kg-day)
Acute Dose Rate, total (mg/kg-day)
Maximum gas phase concentration (|ig/m3)
Maximum DBP in respirable particle (RP) concentration, air
(l-ig/mg)
Maximum respirable particle concentration, air (mg/m3)
Fraction of time in environment (unitless)
Inhalation rate after use (m3/h)
Conversion factor (24 h/day)
Body weight (kg)
Conversion factor (1,000 |ig/mg)
Acute dose rate for ingestion after inhalation (CEM AING1 Model) was calculated as follows:
Equation Apx A-5. Acute Dose Rate from Ingestion After Inhalation
ADR„
[(DBPRPqirmax * RPqirmax * IFrp) + (DBPDustair _mm, x Dustairmax x IFDust) + (DBP Abrairmax x Abrairmax x IFAbr)\ x InhalAfter x CF1
Where:
ADRiai
DBPRPair max
RP air max
IFTsp
DBPDustair max
Dust ¦
u u-oiairjnax
I^Dust
DBPAbrair
avg
Abvair avg
lFAbr
InhalAfter
CF,
BW
cf2
BW x CF2
Acute Dose Rate from Ingestion and Inhalation (mg/kg-day)
Maximum DBP in respirable particles (RP) concentration, air
(l-ig/mg)
Maximum RP concentration, air (mg/m3)
RP ingestion fraction (unitless)
Maximum DBP in dust concentration, air (|ig/mg)
Maximum dust concentration, air (mg/m3)
Dust ingestion fraction (unitless)
Maximum DBP in abraded particle concentration, air (|ig/mg)
Maximum abraded particle concentration, air (mg/m3)
Abraded particle ingestion fraction (unitless)
Inhalation rate after use (m3/h)
Conversion factor (24 h/day)
Body weight (kg)
Conversion factor (1,000 mg/g)
Acute daily dose rate for ingestion of article mouthed (CEM AING2 Model) was calculated as follows:
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EquationApx A-6. Acute Dose Rate for Ingestion of Article Mouthed
MR x CAx Dmx EDac x CF1
An n — _
BW x ATac x CF2
Where:
ADR = Acute Dose Rate (mg/kg-day)
MR = Migration rate of chemical from article to saliva (mg/cm2/h)
CA = Contact area of mouthing (cm2)
Dm = Duration of mouthing (min/h)
EDac = Exposure duration, acute (days)
CF1 = Conversion factor (24 h/day)
BW = Body weight (kg)
ATac = Averaging time, acute (days)
CF2 = Conversion factor (60 min/h)
See Section 2.2.1 for migration rate inputs and determination of these values.
Acute dose rate for incidental ingestion of dust (CEM AING3 Model) was calculated as follows:
The article model named E6 in CEM calculates DBP concentration in small particles, termed respirable
particles (RP), and large particles, termed dust, that are settled on the floor or surfaces. The model
assumes the particles bound to DBP are available via incidental dust ingestion assuming a daily dust
ingestion rate and a fraction of the day that is spent in the zone with the DBP-containing dust. The
model uses a weighted dust concentration, shown in Equation Apx A-6.
Equation Apx A-7. Acute Dust Concentration
_ {RPfloormax * ^ B P RP[{0or_max) (PuStfi00r max * DBPDuStji 0 0r_inax) ^ Ay t [[0 0r_max * DBP AbAYtfi00r_max)
US ac_wgt (t^P A- Dust A- AhArt ^
yi orfioorjnax ~ uLfloor_max ' riuni ^fioorjnaxJ
Where:
Dustac wgt = Acute weighted dust concentration (|ig/mg)
RPfloormax = Maximum RP mass, floor (mg)
DBPRPfioor max = Maximum DBP in RP concentration, floor (|ig/mg)
Dustfioor max = Maximum dust mass, floor (mg)
DBPDustfioor max = Maximum DBP in dust concentration, floor (|ig/mg)
AbArtfioor max = Maximum abraded particles mass, floor (mg)
DBPAbArtfioor max = Maximum floor dust DBP concentration (|ig/mg)
Equation Apx A-8. Acute Dose Rate for Incidental Ingestion of Dust
Dustac wgt x FracTime x Dusting
ADR =
BW x CF
Where:
ADR = Acute dose rate (mg/kg-day)
Dustac wgt = Acute weighted dust concentration (|ig/mg)
FracTime = Fraction of time in environment (unitless)
Dusting = Dust ingestion rate (mg/day)
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BW = Body weight (kg)
CF = Conversion factor (1,000 |ig/mg)
The above equations assume DBP can volatilize from the DBP-containing article to the air and then
partition to dust. Alternately, DBP can partition directly from the article to dust in direct contact with the
article. This is also estimated in A ING3 Model assuming the original DBP concentration in the article
is known, and the density of the dust and dust-air and solid-air partitioning coefficients are either known
or estimated as presented in E6. The model assumes partitioning behavior dominates, or instantaneous
equilibrium is achieved. This is presented as a worst-case or upper-bound scenario.
EquationApx A-9. Concentration of DBP in Dust
n _ Q)_art ^ Kdust ^ CF
d ~ K
Asolid
Where:
Cd = Concentration of DBP in dust (mg/mg)
Cq art = Initial DBP concentration in article (mg/cm3)
Kdust = DBP dust-air partition coefficient (m3/mg)
CF = Conversion factor (106 cm3/m3)
Ksoiid = Solid air partition coefficient (unitless)
Once DBP concentration in the dust is estimated, the acute dose rate can be calculated. The calculation
relies on the same upper end dust concentration.
Equation Apx A-10. Acute Dose Rate from Direct Transfer to Dust
Cd x FracTime x Dusting
adrdtd = ^
Where:
ADRdtd = Acute Dose Rate from direct transfer to dust (mg/kg-day)
Cd = Concentration of DBP in dust (mg/mg)
FracTime = Fraction of time in environment (unitless)
Dusting = Dust ingestion rate (mg/day)
BW = Body weight (kg)
Acute dose rate for ingestion ofproduct swallowed (CEM PING1 module) was calculated as follows:
Equation Apx A-ll. Acute Dose Rate for Ingestion of Product Swallowed by Mouthing
FQac x M x WF x Fing x CFl x EDac
ADR =
BW x ATac
Where:
ADR = Acute Dose Rate (mg/kg-day)
FQac = Frequency of use, acute (events/day)
M = Mass of product used (g)
WF = Weight fraction of chemical in product (unitless)
Fing = Fraction of product ingested (unitless)
CF1 = Conversion factor (1,000 mg/g)
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EDac = Exposure duration, acute (days)
ATac = Averaging time, acute (days)
BW = Body weight (kg)
The model assumes that the product is directly ingested as part of routine use, and the mass is dependent
on the weight fraction and use patterns associated with the product.
A.2 Non-Cancer Chronic Dose
Chronic average daily dose rate for inhalation of product used in an environment (CEM P INHl
Model) was calculated as follows:
EquationApx A-12. Chronic Average Daily Dose Rate for Inhalation of Product Used in an
Environment
Cnir x Inh x FQ x Drr x ED
CADD = —
BW x AT x CF1 x CF2
Where:
CADD =
Chronic average daily dose (mg/kg-day)
C ¦ =
uair
Concentration of chemical in air (mg/m3)
Inh =
Inhalation rate (m3/h)
FQ =
Frequency of use (events/year)
Dcr ~
Duration of use (min/event), chronic
ED
Exposure duration (years of product usage)
BW =
Body weight (kg)
AT
Averaging time (years)
CFi =
Conversion factor (365 days/year)
cf2 =
Conversion factor (60 min/h)
CEM uses two defaults inhalation rates that trace to the Exposure Factors Handbook (see TableApx
A-l footnote), one when the person is using the product and another after the use has ended. Table Apx
A-l shows the inhalation rates by receptor age category for during and after product use.
Table Apx A-l. Inhalation Rates Used in CEM Product Models
Age Group
Inhalation Rate During Use
(mJ/h)"
Inhalation Rate After Use
(m3/h) b
Adult (21+ years)
0.74
0.61
Youth (16-20 years)
0.72
0.68
Youth (11-15 years)
0.78
0.63
Child (6-10 years)
0.66
0.5
Small Child (3-5 years)
0.66
0.42
Infant (1-2 years)
0.72
0.35
Infant (<1 year)
0.46
0.23
"Table 6-2. light intensity values CU.S. EPA, 201 la)
Table 6-1 ( 11a)
The inhalation dose is calculated iteratively at a 30-second interval during the first 24 hours and every
hour after that for 60 days, taking into consideration the chemical emission rate over time, the volume of
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the house and each zone, the air exchange rate and interzonal airflow rate, and the exposed individual's
locations and inhalation rates during and after product use.
Chronic average daily dose rate for inhalation from article placed in environment (CEM AINHl
Model) was calculated as follows:
EquationApx A-13. Chronic Average Daily Dose Rate for Inhalation from Article Placed in
Environment in Air
„v„ x FracTime x InhalAfter x CFi
CAD D Ajr = gas~avg 1 -
Air BW x CF7
Equation Apx A-14. Chronic Average Daily Dose Rate for Inhalation from Article Placed in
Environment in Particulate
™ _ DBPRPair_avg x RPair_avc, x (1 - IFRP)FracTime x InhalAfter x CF1
L AD ^Particulate
BW X CF,
Equation Apx A-15. Total Chronic Average Daily Dose Rate for Inhalation of Particulate and Air
CADDtotal — CADDAir + CAD DpartiCUiate
Where:
CADDAir
CADDParticuiate
CADDtotai
r
ugas_avg
DBPRPairavg
RPair_avg
IFrp
FracTime
InhalAfter
CFi
BW
cf2
Chronic average daily dose, air (mg/kg-day)
Chronic average daily dose, particulate (mg/kg-day)
Chronic average daily dose, total (mg/kg-day)
Average gas phase concentration (|ig/m3)
Average DBP in respirable particles (RP) concentration, air
(l-ig/mg)
Average RP concentration, air (mg/m3)
RP ingestion fraction (unitless)
Fraction of time in environment (unitless)
Inhalation rate after use (m3/h)
Conversion factor (24 h/day)
Body weight (kg)
Conversion factor (1,000 |ig/mg)
Chronic average daily dose rate for ingestion after inhalation (CEM AING1 Model) was calculated as
follows:
The CEM Article Model, E6, estimates DBP concentrations in small and large airborne particles.
Although these particles are expected to be inhaled, not all are able to penetrate the lungs and be trapped
in the upper airway and subsequently swallowed. The model estimates the mass of DBP bound to
airborne small particles, respirable particles (RP), and large particles {i.e., dust) that are inhaled and
trapped in the upper airway. The fraction that is trapped in the airway is termed the ingestion fraction
(IF). The mass trapped is assumed to be available for ingestion.
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EquationApx A-16. Chronic Average Daily Dose Rate from Ingestion After Inhalation
CADDiai
[(¦
DBPRPair avg x RPairavg x
/Frp) + (pBPDustalr_avg x Dustairavg x 1FDus^ + (DBPAbrc
V A fay
airjxvg rru' airjavg
x /F/li)r)j x InhalAfter x CF±
Where:
CADD
IAI
DBPRPair avg
RPair_avg
IFrp
DBPDustair avg
Dust ¦
u uj iair_avg
I^Dust
DBPAbrair
avg
Abvair avg
l^Ahr
InhalAfter
CFi
BW
cf2
BW x CF2
Chronic average daily dose from ingestion after inhalation
(mg/kg-day)
Average DBP in RP concentration, air (|ig/mg)
Average RP concentration, air (mg/m3)
RP ingestion fraction (unitless)
Average DBP dust concentration, air (|ig/mg)
Average dust concentration, air (mg/m3)
Dust ingestion fraction (unitless)
Average DBP in abraded particle concentration, air (|ig/mg)
Average abraded particle concentration, air (mg/m3)
Abraded particle ingestion fraction (unitless)
Inhalation rate after use (m3/h)
Conversion factor (24 h/day)
Body weight (kg)
Conversion factor (1,000 mg/g)
Chronic average daily dose rate for ingestion of article mouthed (CEM AING2 Model) was calculated
as follows:
The model assumes that a fraction of the chemical present in the article is ingested via object-to-mouth
contact or mouthing where the chemical of interest migrates from the article to the saliva. See Section
2.2.1 for migration rate inputs and determination of these values.
Equation Apx A-17. Chronic Average Daily Dose Rate for Ingestion of Article Mouthed
MR x CAx Dmx EDcr x CFt
CADD = -
BW x ATcr x CF2
Where:
CADD =
Chronic average daily dose (mg/kg-day)
MR =
Migration rate of chemical from article to saliva (mg/cm2/h)
CA
Contact area of mouthing (cm2)
Dm ~
Duration of mouthing (min/h)
EDcr =
Exposure duration, chronic (years)
CF1 =
Conversion factor (24 h/day)
ATcr =
Averaging time, chronic (years)
BW =
Body weight (kg)
cf2 =
Conversion factor (60 min/h)
Chronic average daily rate for incidental ingestion of dust (CEM AING3 Model) was calculated as
follows:
The article model in CEM E6 calculates DBP concentration in small particles, termed respirable
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particles (RP), and large particles, termed dust, that are settled on the floor or surfaces. The model
assumes these particles, bound to DBP, are available via incidental dust ingestion assuming a daily dust
ingestion rate and a fraction of the day that is spent in the zone with the DBP-containing dust. The
model uses a weighted dust concentration, shown in EquationApx A-18.
EquationApx A-18. Chronic Dust Concentration
Dust,
cr_wgt
(RPfio or_avg
x DBPRPfloor avg) + (Dustfl
oorjxvg
x DBPDustfloor avg) + (AbArtfl0
or_avg
x DBPAbArtfloor avg)
Where:
Dust,
crjwgt
RP
floor_avg
DBPRP,
floor_avg
Dust
¦floor_avg
DBPDust
¦floor_avg
AbArt
¦floor_avg
DBP AbArt
floor_avg
(j^Pfloor_avg Dustfi00r_avg AbAvtfi00r_avg)
Chronic weighted dust concentration (|ig/mg)
Average RP mass, floor (mg)
Average DBP in RP concentration, floor (|ig/mg)
Average dust mass, floor (mg)
Average DBP in dust concentration, floor (|ig/mg)
Average abraded particles mass, floor (mg)
Average floor dust DBP concentration (|ig/mg)
Equation Apx A-19. Chronic Average Daily Dose Rate for Incidental Ingestion of Dust
Where:
CADD
Dustcrwgt
FracTime
Dusting
BW
CF
CADD =
Dustcr wgt x FracTime x Dusting
BW x CF
Chronic average daily dose (mg/kg-day)
Chronic weighted dust concentration (|ig/mg)
Fraction of time in environment (unitless)
Dust ingestion rate (mg/day)
Body weight (kg)
Conversion factor (1,000 |ig/mg)
The above equations assume DBP can volatilize from the DBP-containing article to the air and then
partition to dust. Alternately, DBP can partition directly from the article to dust in direct contact with the
article. This is also estimated in the A ING3 Model assuming the original DBP concentration in the
article is known, and the density of the dust and dust-air and solid-air partitioning coefficients are either
known or estimated as presented in the E6 CEM Model. The model assumes partitioning behavior
dominates, or instantaneous equilibrium is achieved. This is presented as a worst-case or upper-bound
scenario.
A.3 Intermediate Average Daily Dose
The intermediate doses were calculated from the average daily dose, ADD, (|ig/kg-day) CEM output for
that product using the same inputs summarized in Table 2-5 for inhalation and Table 2-9 for dermal.
EPA used professional judgment based on manufacturer and online product use descriptions to estimate
events per day and per month for the calculation of the intermediate dose:
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EquationApx A-20. Intermediate Average Daily Dose Equation
ADD x Event per Month
Intermediate Dose = -
Where:
Events per Day
Intermediate Dose = Intermediate average daily dose, |ig/kg-month
ADD = Average daily dose, |ig/kg-day
Event per Month = Events per month, month-1, see Table Apx A-2
Event per Day = Events per day, day-1, see Table_Apx A-2
Table Apx A-2. Short-Term Event per Month and Day Inputs
Product
Events Per Day
Events Per Month
Automotive adhesives
1
2
Construction adhesives
1
2
Sealing and refinishing sprays (indoor use)
1
2
Sealing and refinishing sprays (outdoor use)
1
2
A.4 Dermal Absorption Dose Modeling for Acute and Chronic Exposures
After calculating dermal absorption dose per event for each lifestage, chronic average daily dose, acute
average daily dose, and intermediate average daily dose were calculated as described below.
Acute dose rate for direct dermal contact with product or article was calculated as follows:
Equation Apx A-21. Acute Dose Rate for Dermal
Dose per Event x Acute Frequency
ADRDermai Averaging Time
Where:
ADRDermai
Dose per Event =
Acute Frequency =
Averaging Time =
Acute dose rate for dermal contact, mg/kg-day by body weight
Amount of chemical absorbed per use, mg/kg by body weight
Number of exposure events per averaging period
Acute averaging time, day 1
Chronic average daily dose rate for direct dermal contact with product or article was calculated as
follows:
Equation Apx A-22. Chronic Average Daily Dose Rate for Dermal
Dose per Event x Chronic Frequency
r Ann — L i ±_
L,fiULl£)ermai .
Averaging Time
Where:
CADD
Dermal
Dose per Event
Chronic Frequency
Averaging Time
Chronic dermal rate for dermal contact, mg/kg-day by body
weight
Amount of chemical absorbed per use, mg/kg by body weight
Number of exposure events per averaging period
Chronic averaging time, day 1
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