United StitM
4>EPA
Agency
Offfce of
Toxic Substarwsw
Washington, D.C. 20480
Methods for Assessing
Exposure to Chemical
Substances
Volume 7
Methods for Assessing
Consumer Exposure to
Chemical Substances
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EPA 560/5-85-007
APRIL 1987
METHODS FOR ASSESSING EXPOSURE
TO CHEMICAL SUBSTANCES
Volume 7
Methods for Assessing Consumer Exposure
to Chemical Substances
by
Patricia D. Jennings, Karen A. Hammerstrom,
Leslie Coleman Adkins, Thompson Chambers,
Douglas A. Dixon
EPA Contract No. 68-02-3968
Project Officer
Elizabeth F. Bryan
Exposure Evaluation Division
Office of Toxic Substances
Washington, D.C. 20460
U.S. ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF PESTICIDES AND TOXIC SUBSTANCES
WASHINGTON, D.C. 20460
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11
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DISCLAIMER
This document has been reviewed and approved for publication by the
Office of Toxic Substances, Office of Pesticides and Toxic Substances,
U.S. Environmental Protection Agency. The use of trade names or
commercial products does not constitute Agency endorsement or
recommendation for use.
ill
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FOREWORD
This document 1s one of a series of volumes, developed for the U.S.
Environmental Protection Agency (EPA), Office of Toxic Substances (OTS),
that provides methods and Information useful for assessing exposure to
chemical substances. The methods described 1n these volumes have been
Identified by EPA-OTS as having utility In exposure assessments on
existing and new chemicals 1n the OTS program. These methods are not
necessarily the only methods used by OTS, because the state-of-the art 1n
exposure assessment 1s changing rapidly, as Is the availability of
methods and tools. There 1s no single correct approach to performing an
exposure assessment, and the methods 1n these volumes are accordingly
discussed only as options to be considered, rather than as rigid
procedures.
Perhaps more Important than the optional methods presented 1n these
volumes 1s the general Information catalogued. These documents contain a
great deal of non-chem1cal-spedf1c data which can be used for many types
of exposure assessments. This Information Is presented along with the
methods 1n Individual volumes and appendices. As a set, these volumes
should be thought of as a catalog of Information useful 1n exposure
assessment, and not as a "how-to" cookbook on the subject.
The definition, background, and discussion of planning exposure
assessments are discussed 1n the Introductory volume of the series
(Volume 1). Each subsequent volume addresses only one general exposure
setting. Consult Volume 1 for guidance on the proper use and
Interrelations of the various volumes and on the planning and Integration
of an entire assessment.
The titles of the nine basic volumes are as follows:
Volume 1 Methods for Assessing Exposure to Chemical Substances
(EPA 560/5-85-001)
Volume 2 Methods for Assessing Exposure to Chemical Substances 1n the
Ambient Environment (EPA 560/5-85-002)
Volume 3 Methods for Assessing Exposure from Disposal of Chemical
Substances (EPA 560/5-85-003)
Volume 4 Methods for Enumerating and Characterizing Populations Exposed
to Chemical Substances (EPA 560/5-85-004)
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Volume 5 Methods for Assessing Exposure to Chemical Substances In
Drinking Water (EPA 560/5-85-005)
Volume 6 Methods for Assessing Occupational Exposure to Chemical
Substances (EPA 560/5-85-006)
Volume 7 Methods for Assessing Consumer Exposure to Chemical Substances
(EPA 560/5-85-007)
Volume 8 Methods for Assessing Environmental Pathways of Food
Contamination (EPA 560/5-85-008)
Volume 9 Methods for Assessing Exposure to Chemical Substances
Resulting from Transportation-Related Spills (EPA 560/5-85-009)
Because exposure assessment 1s a rapidly developing field, Its
methods and analytical tools are quite dynamic. EPA-OTS Intends to Issue
periodic supplements for Volumes 2 through 9 to describe significant
Improvements and updates for the existing Information, as well as adding
short monographs to the series on specific areas of Interest. The first
four of these monographs are as follows:
Volume 10 Methods for Estimating Uncertainties In Exposure Assessments
(EPA 560/5-85-014)
Volume 11 Methods for Estimating the Migration of Chemical Substances
from Solid Matrices (EPA 560/5-85-015)
Volume 12 Methods for Estimating the Concentration of Chemical
Substances in Indoor A1r (EPA 560/5-85-016)
Volume 13 Methods for Estimating Retention of Liquids on Hands
(EPA 560/5-85-017)
Elizabeth F. Bryan, Chief
Exposure Assessment Branch
Exposure Evaluation Division (TS-798)
Office of Toxic Substances
vi
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ACKNOWLEDGEMENTS
This report was prepared by Versar Inc. of Springfield, Virginia, for
the EPA Office of Toxic Substances, Exposure Evaluation Division,
Exposure Assessment Branch (EAB) under EPA Contract Nos. 68-01-6271 and
68-02-3968. The EPA-EAB Task Managers for this task were Karen A.
Hammerstrom and Stephen H. Nacht; the EPA Program Managers were Michael
A. Callahan and Elizabeth F. Bryan. The support and guidance given by
these, and other EPA personnel, is gratefully acknowledged.
A number of Versar personnel have contributed to this task over the
period of performance, as listed below:
Program Management
Task Management
Principal Investigator
Technical Support
Editing
Secretarial/Clerical
- Gayaneh Contos
Patricia Jennings
Douglas Dixon
- Patricia Jennings
- Leslie Adkins
Thompson Chambers
John Doria
- Juliet Crumrine
Barbara Malczak
- Shirley Harrison
Sue Elhussein
Mary Ann Rish
Kathy Zavada
Franklin Clay
Lucy Gentry
Donna Barnard
Lynn Maxfield
Kammi Johannsen
Jan Hunter
LaVonnia Brown
vii
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V111
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TABLE OF CONTENTS
Page No.
1. INTRODUCTION ; 1
1.1 Background and Purpose 1
1.2 Consumer Products Considered by This Methods
Report 1
1.3 Overview of Methodological Approach 2
2. PHYSICAL-CHEMICAL PROPERTIES 15
2.1 General Property Information 15
2.2 Data Gathering 15
2.2.1 Sources of Experimental Data 15
2.2.2 Methods for Estimating Physical-Chemical
Properties 21
2.3 Summary 21
3. PRODUCT-SPECIFIC DATA REQUIRED TO ASSESS EXPOSURE 25
3.1 Amount of Chemical Substance Applied Directly to
Surfaces 25
3.2 Amount of a Chemical Substance Released by Use
of Aerosol and Pump Spray Products and by Pouring
or Spilling Liquids and Powders 31
3.3 Identification of Consumer Products and
Formulations 34
4. METHODS FOR ESTIMATING RELEASE OF CHEMICAL SUBSTANCES
FROM CONSUMER PRODUCTS AND CONCENTRATIONS OF CHEMICAL
SUBSTANCES IN INDOOR AIR 45
4.1 Overview of Mechanisms of Chemical Release and
Factors Affecting Concentrations to Which Consumers
are Exposed 45
4.1.1 Chemical Release Mechanisms 46
4.1.2 Factors Affecting Exposure Concentrations .. 48
4.2 Monitoring Data 49
4.3 Methods to Estimate Release of Chemical Substances
from Consumer Products 49
ix
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TABLE OF CONTENTS (continued)
Page No.
4.3.1 Release Rate of Chemical Substances in
Aerosol Consumer Products 50
4.3.2 Release Rate of Chemical Substances from
Liquid Films Applied to Surfaces 51
4.3.3 Chemical Release from Liquids and Solids 60
4.4 Methods for Estimating Concentrations in Indoor Air . 64
4.4.1 Concentrations Resulting from Instantaneous
Releases of Chemical Substances 67
4.4.2 Concentrations Resulting from Continuous Release
of Chemical Substances 73
4.4.3 Concentrations Resulting from Time-Dependent
Releases of Chemical Substances 76
EXPOSED POPULATIONS 83
5.1 Identification of Exposed Populations 83
5.2 Enumeration of the Exposed Population 83
5.2.1 Enumeration of Exposed Populations via
Simmons Market Research Bureau Reports 84
5.2.2 Enumeration of Exposed Populations via
Production and Sales Data 85
5.2.3 Enumeration of Exposed Populations via
Chemical-Specific Information 86
5.3 Characterization of Exposed Population 86
6. EXPOSURE ANALYSIS 89
6.1 Exposure Pathways and Routes 89
6.1.1 Inhalation Pathways 89
6.1.2 Dermal Pathways 91
6.1.3 Ingestion Pathways 92
6.1.4 Other Pathways 94
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TABLE OF CONTENTS (continued)
Page No.
6.2 Exposure Calculation 94
6.2.1 Frequency of Use 94
6.2.2 Inhalation Exposure 95
6.2.3 Dermal Exposure TOO
6.2.4 Ingestlon Exposure Ill
6.3 Absorbed Dose 113
6.3.1 Inhalation 113
6.3.2 Dermal 113
6.3.3 Ingestlon 118
7. REFERENCES 121
APPENDIX A - Method for Estimating Inhalation Exposure to
Partlculates Discharged from Consumer Products .. 127
APPENDIX B - Simmons Market Research Bureau (SMRB) Reports ... 145"
APPENDIX C - Alphabetical Listing of Variables Used 1n This
Volume 171 >' \
^APPENDIX D - Average Body Weights of Humans by Age Group 177" &'
APPENDIX E - Derivation of Equations for Estimating --k-'"'<'
Concentrations of Chemical Substances In Indoor , -
Air 179
xl
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LIST OF TABLES
Page No.
Table 1. Consumer Products Found in the Typical U.S.
Household 3
Table 2. Product Form Terminology Adopted for Use in This
Report 8
Table 3. Operations for Performing a Consumer Exposure
Assessment for a Given Chemical 11
Table 4. Sections of Volume 7 to Use in Calculating
Inhalation Exposure 13
Table 5. Sections of Volume 7 to Use in Estimating Exposure
via Dermal Contact with and Ingestion of Consumer
Products 14
Table 6. Summary of Physical-Chemical Properties Relevant to
Consumer Exposure 16
Table 7. Major Computerized Data Bases for Obtaining
Physical-Chemical Properties 18
Table 8. Major Published References for Obtaining Physical-
Chemical Properties 19
Table 9. Sources of Information for Estimating Physical-
Chemical Properties 22
Table 10. Labor Production and Material Consumption Rates for
Coatings Applied to Surfaces By Labor Category and
Method of Application 27
Table 11. Experimentally Determined Density Values for
Select Consumer Products 29
Table 12. Mass of Aerosol Product Released Per Use 32
Table 13. Estimates of Overspray During Application 33
Table 14. List of Functional Components as Weight Fraction in
Latex Wall Paint 38
xii
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LIST OF TABLES (continued)
Page No.
Table 15. List of Functional Components as Weight Fraction In
Aerosol Furniture Polish 39
Table 16. List of Functional Components as Weight Fraction 1n
General, All-Purpose Liquid Cleaner 40
Table 17. List of Functional Components as Weight Fraction 1n
Motor 011 41
Table 18. Weight Fractions of Functional Components - Floor
Wax/Polish 43
Table 19. Functional Components as Weight Fraction In Vinyl
Upholstery Cleaners 44
Table 20. Diffusion Coefficients (@ 25°C and 1 atm) for
Selected Organic Chemicals 1n A1r 59
Table 21. Diffusion Coefficients In Aqueous Solutions at
Infinite Dilution 62
Table 22. Values for Mixing Factor Recommended for Several
Common A1r Supply System Configurations 69
Table 23. Typical Room Volumes 71
Table 24. Air Changes Occurring Under Average Conditions in
Residences Exclusive of Air Provided for
Ventilation 72
Table 25. Summary of Human Inhalation Rates for Men, Women
and Children by Activity Level 98
Table 26. Film Thickness Values of Selected Liquids
Under Various Experimental Conditions 103
Table 27. Experimentally Determined Values for Density and
Kinematic Viscosity of Six Selected Liquids 107
Table 28. Surface Area of Body Regions 109
xiii
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LIST OF TABLES (continued)
Table 29 Values of Respirable and Nonrespirable Fraction
Page No.)
Table 30.
Table 31.
Table 32.
Table 33.
of Partlculates for Selected Consumer Products ...
SMRB Reports (1983) by Volume
Products Listed In SMRB Reports (1983) by
Product Category
An Alphabetical Listing of Variables Used In
Th1 s Volume
Averaoe Bodv Welahts of Humans bv Aae Grouo
140
147
148
172
178
XIV
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LIST OF FIGURES
Page No.
Figure 1.
Figure 2.
Figure 3.
Figure 4.
Figure 5.
Mass of Volatile Chemical Substance Remaining on
Surface of Each Square Foot of Board as a Function
of Time 53
Fraction Migrated as a Function of «p for Well-Mixed
Domains 65
ICRP Model of Regional Respiratory Tract
Deposition as a Function of Particle Size
134
Total Deposition of Particulates 1n the Respiratory
Tract As a Function of Particle Size 135
Pulmonary Deposition of Particulates as a Function
of Particulate Size 136
XV
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XV1
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1. INTRODUCTION
This volume 1s the seventh In a series of thirteen volumes presenting
methods for assessing exposures to chemical substances; the reports are
being developed for the U.S. Environmental Protection Agency, Office of
Toxic Substances. This volume presents methods and supporting
Information for estimating exposures to chemical substances In consumer
products. The methods that are presented 1n this volume to estimate
inhalation and dermal exposure are the basis of user-friendly, personal
computer programs that comprise the Computerized Consumer Exposure Models
(CCEH). CCEM was developed for the Exposure Evaluation Division of the
Office of Toxic Substances. Much of the supporting Information included
in this volume is also included in CCEM. Such data Include room air
exchange rates, human inhalation rates, skin surfaces areas, film
thickness values for liquids on skin, mixing factors, and body weights of
humans. The background and purpose of this report, the consumer products
considered by this methods report, and its methodological framework, are
discussed in the following subsections.
1.1 Background and Purpose
The Toxic Substances Control Act (TSCA) of 1976 (PL94-469) authorizes
the U.S. Environmental Protection Agency (EPA) to assess human and
environmental exposure to chemical substances. An exposure assessment
for a chemical substance attempts to determine the amounts of that
chemical substance to which populations are exposed, as well as to
identify and estimate the size of exposed populations. The EPA Office of
Toxic Substances (OTS), Exposure Evaluation Division (EED), is
responsible for conducting exposure assessments for new and existing
chemical substances in support of Sections 4, 5, and 6 of TSCA.
Exposure assessments for each of the exposure categories (i.e.,
ambient, occupational, food, drinking water, and consumer) have
historically been limited by a lack of complete and reliable data.
Accurate calculation of exposure to a chemical substance relies on actual
monitoring data from the media (e.g., air, water, food, surfaces)
containing the chemical and the entire time period during which exposure
occurs. For most chemical substances, however, these data are
insufficient, difficult to obtain, or non-existent, necessitating
estimation of exposure. The goal of this report is to catalog pertinent
Information, data bases, and tools, and to provide a systematic approach
or methodology whereby the exposure to a given chemical substance in
consumer products can be estimated at any desired level of detail.
1.2 Consumer Products Considered by This Methods Report
Consumer products are defined in this report as products containing
chemical constituents to which human or environmental exposure may occur
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as a result of the use of the consumer product. This is a broad
definition, which Incorporates a multitude of products and product groups
and crosses several regulatory boundaries.
The product groups that have been specifically excluded from the
scope of this exposure assessment methods report are listed below. These
product groups pose analytical complications not addressed at this time,
are covered by other methods reports, or are excluded from TSCA authority.
Tobacco and tobacco products.
Non-consumer pesticides and fertilizers.
Business products (I.e., copying machines).
Firearms, ammunitions, and explosives.
Food, food products, and food additives/preservatives.
Products containing radioactive materials.
Products used exclusively for hobbies and crafts.
Drugs and medical devices.
The criteria used by the FDA to distinguish between cosmetics and drugs
state that any preparation used only for cleansing or beautification of
the skin, hair, or fingernails 1s considered a cosmetic. Any claim of a
medicinal nature, even if it is only implied, immediately places the
product in the drug class. (Products such as bandages, lip balms, and
suntan lotions are Included 1n this methods report because of their
intended protective, not medicinal, purposes.)
Finally, exposures resulting from the use of any form of
transportation are limited to cleaning, waxing, and polishing automobiles
and exposures to synthetic Interior materials.
As part of the general data collection portion of this methods
report, a comprehensive list of consumer products found in typical
American households was compiled and 1s presented in Table 1. This is
a working list that is believed to reflect those products and product
groups of commonly used items which, through various modes of consumption
(exposure scenarios), lead to exposure to chemical constituents. This
list is somewhat arbitrary and subjective. Creating a finite set of
products, however, was necessary to begin the task of collecting the vast
amount of product-specific information. Definitions of product types,
such as aerosol and liquid, are cited in Table 2.
1.3 Overview of Methodological Approach
This report presents methods and data recommended for estimating
exposure to chemical substances in consumer products. Methods for
estimating both "active" and "passive" exposure to chemical substances in
consumer products are presented. Active exposures are defined as
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o
Table 1. Consumer Products Found in the
Typical U.S. Household1
Consumer product category
Consumer product
Cosmetics hygiene products
Adhesive bandages
Bath additives (liquid)
Bath additives (powder)
Cologne/perfume/aftershave
Contact lens solutions
Deodorant/antiperspirant (aerosol)
Deodorant/antiperspi rant
(wax and 1 iquid)
Depilatories
Facial makeup
Fingernail cosmetics
Hair coloring/tinting products
Hair conditioning products
Hairsprays (aerosol)
Lip products
Mouthwash/breath freshener
Sanitary napkins and pads
Shampoo
Shaving creams (aerosols)
Skin creams (non-drug)
Skin oils (non-drug)
Soap (toilet bar)
Sunscreen/suntan products
Talc/body powder (non-drug)
Toothpaste
Waterless skin cleaners
Household furnishings
Carpeting
Draperies/curtains
Rugs (area)
Shower curtains
Vinyl upholstery, furniture
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Table 1. (continued)
Consumer product category
Consumer product
Garment conditioning products
Anti-static spray (aerosol)
Leather treatment (liquid and wax)
Shoe polish
Spray starch (aerosol)
Suede cleaner/polish (liquid
and aerosol)
Textile water-proofing (aerosol)
Household maintenance products
Adhesive (general) (liquid)
Bleach (household) (liquid)
Bleach (see laundry)
Candles
Cat box litter
Charcoal briquets
Charcoal lighter fluid
Drain cleaner (liquid and powder)
Dishwasher detergent (powder)
Dishwashing liquid
Fabric dye (DIY)
Fabric rinse/softener (liquid)
Fabric rinse/softener (powder)
Fertilizer (garden) (liquid)
Fertilizer (garden) (powder)
Fire extinguishers (aerosol)
Floor polish/wax (liquid)
Food packaging and packaged food
Furniture polish (liquid)
Furniture polish (aerosol)
General cleaner/disinfectant (liquid)
General cleaner (powder)
General cleaner/disinfectant
(aerosol and pump)
General spot/stain remover (liquid)
General spot/stain remover (aerosol
and pump)
Herbicide (garden-patio) (liquid and
aerosol)
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Table 1. (continued)
Consumer product category
Consumer product
Household maintenance products
(continued)
Insecticide (home and garden)
(powder)
Insecticide (home and garden)
(aerosol and pump)
Insect repellent (liquid and
aerosol)
Laundry detergent/bleach (liquid)
Laundry detergent (powder)
Laundry pre-wash/soak (powder)
Laundry pre-wash/soak (liquid)
Laundry pre-wash/soak (aerosol and
pump)
Lubricant oil (liquid)
Lubricant (aerosol)
Matches
Metal polish
Oven cleaner (aerosol)
Pesticide (home) (solid)
Pesticide (pet dip) (liquid)
Pesticide (pet) (powder)
Pesticide (pet) (aerosol)
Pesticide (pet) (collar)
Petroleum fuels (home) (liquid and
aerosol)
Rug cleaner/shampoo (liquid and
aerosol)
Rug deodorizer/freshener (powder)
Room deodorizer (solid)
Room deodorizer (aerosol)
Scouring pad
Toilet bowl cleaner
Toilet bowl deodorant (solid)
Water-treating chemicals
(swimming pools)
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Table 1. (continued)
Consumer product category
Consumer product
Home building/improvement
products (DIY)
Adhesives, specialty (liquid)
Ceiling tile
Caulks/sealers/fillers
Dry wall/wall board
Flooring (vinyl)
House Paint (interior) (liquid)
House Paint and Stain (exterior)
(liquid)
Insulation (solid)
Insulation (foam)
Paint/varnish removers
Paint thinner/brush cleaners
Patching/ceiling plaster
Roofing
Refinishing products
(polyurethane, varnishes, etc.)
Spray paints (home) (aerosol)
Wall paneling
Wall paper
Wall paper glue
Automobile-related products
Antifreeze
Car polish/wax
Fuel/lubricant additives
Gasoline/diesel fuel
Interior upholstery/components,
synthetic
Motor oil
Radiator flush/cleaner
Automotive touch-up paint
(aerosol)
Windshield washer solvents
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Table 1. (continued)
Consumer product category Consumer product
Personal materials Clothes/shoes
Diapers/vinyl pants
Jewelry
Printed material (colorprint,
newsprint, photographs)
Sheets/towels
Toys (intended to be placed
in mouths)
DIY = Do It Yourself.
' A subjective listing based on consumer use profiles conducted by
Versar.
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Table 2. Product Form Terminology Adopted
for Use in This Report
Term
Descriptive definition
Aerosol
Pump
Liquid
Any product dispensed from a pressurized
can. The state of the product following
delivery from the aerosol can includes
mists/aerosols, foams, liquids, and
powders.
Any liquid product dispensed from an
unpressurized container via a pumping
trigger.
Any liquid product dispensed by pouring
from its container. This includes a
"roll-on" or similar liquid dispensing
container.
Powder
Solid
Gel/wax
Any powdered product that can be poured
or "dusted" from its container.
Powdered products include crystals and
granules.
A solid product; e.g., moth balls,
though they are crystalline in nature
and are poured from their containers,
are considered a "solid" product.
Any viscous liquid, gel, wax, or paste
squeezed or scooped from its container.
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exposures resulting to the user of a consumer product during active use
of the product (e.g., exposures to chemical substances 1n paints during
the act of painting). Passive exposures pertain to exposures that occur
(1) to the user after active use has ceased, (2) to non-users who are
passively exposed as a result of user activities, and (3) to persons In
the environs of products, such as solid air fresheners, that result
exclusively 1n passive exposures.
The methods for performing consumer exposure assessments are
discussed 1n the following five sections:
Section 2 - Physical-Chemical Properties
Section 3 - Product-Specific Data Required to Assess Exposure
Section 4 - Methods for Estimating Release of Chemicals from Consumer
Products and Concentrations of Chemicals in External Media
Section 5 - Exposed Populations
Section 6 - Exposure Analysis
Appendix A of this report contains methods for estimating inhalation
exposure to particulates discharged from consumer products. Appendix B
includes guides to the individual Simmons Market Research Bureau (SMRB)
reports and to the products included in each volume, respectively.
Appendix C includes an alphabetical listing of all variables used in
Volume 7 of Methods for Assessing Exposure to Chemical Substances. A
definition of each variable and the units in which it is expressed are
also included in Appendix C.
In developing the methods, a series of chemical-, product- and
environment-specific questions were addressed:
Chemical-specific:
Product-specific:
Environment-specific:
How much of a chemical is in the product?
How much is permanently bound in the product
and unavailable for exposure?
How is the product used, and for how long?
How are chemical constituents released through
use?
How much of the product 1s used and by whom?
Where is the product used?
How do ventilation, dilution, etc., affect
available concentrations?
By answering these questions for a range of consumer products, this
methods report attempts to supply the analytical tools necessary for
estimating exposures resulting from various typical consumer activities
and the means by which other analytical tools can be developed to
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calculate values for more unusual consumer exposure situations. An
effort Is made throughout the report to explain the rationale behind the
approaches followed, the derivation of all equations and models, the
assumptions and estimates used, and any Inherent limitations.
The basic steps for performing a consumer exposure assessment for a
given chemical are to Identify the products In which It appears, Identify
appropriate exposure scenarios (detailed circumstances in which consumer
exposure occurs) for each of the products, gather the data required by
each scenario, calculate an exposure or dose based on the equation and
parameter values delineated in each scenario, and enumerate the
populations exposed (both actively and passively). A more detailed
scheme of methodological operations is presented in Table 3. These
method components are intentionally called operations Instead of steps to
discourage the notion that they must be fulfilled In sequential order.
Methods for assessing exposure to chemical substances in consumer
products are delineated in this volume for several pathways of exposure.
Sections of this volume to use in estimating inhalation exposure during
use of consumer products are presented in Table 4. Sections of this
volume to use in estimating dermal and Ingestion exposure during use of
consumer products are presented in Table 5.
10
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Table 3. Operations for Performing a Consumer Exposure
Assessment for a Given Chemical
Method operations
Related data needs
Identify consumer products
that contain chemical
Identify pertinent exposure
routes
>:: -v
Synonyms and CAS #
Information on whether chemical will
be a product constituent or
residual of product processing
Physical -chemical properties
Basic information on product use
patterns
States of products before, during,
and after use
Oevelop/select appropriate"
exposure scenarios
Based on scenario, select
appropriate values for key
parameters (ranges and typical
values)
Determine amount of chemical
in each product
Identification of key parameters (e.g.,
frequency of product use,
duration of each use, amount of
product delivered in each use,
inhalation rates, etc.)
Physical -chemical properties
Specific information on product
use patterns
Environmental parameters
(e.g., room size, ventilation)
Chemical engineering processes
related to product formulation
Weight percentages of constituents
in each product
Weight percentages of chemical in
each constituent
11
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Table 3. (continued)
Method operations
Related data needs
Determine release of chemical
from product
Determine concentration of
chemical available for
exposure
Calculate exposure
Calculate dose (optional)
Physical-chemical properties
Release mechanism analysis
Input from previous three
operations
Input from all previous
operations
Exposure value
Physical-chemical properties
Pharmacokinetics data
Enumerate exposed populations
(active and passive)
Input from product identification
and key scenario parameters
Market data
General population/housing
statistics
12
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c
Table 4. Sections of Volume 7 to Use in Estimating Inhalation Exposure
Exposure pathway
Release rate of chemical
substance to air
Concentration of
chemical substance
in air
Levels to which
consumers are
exposed
Inhalation of a chemical substance that is a
component of aerosols formed while spilling
or pouring a liquid or powder
Inhalation of a chemical substance during continuous
release of the contents of a pressurized aerosol
product
Inhalation of a chemical substance during
intermittent release of the contents of a
pressurized aerosol product, in which the time
between releases is on the order of a few seconds
Inhalation of a chemical substance during its
evaporation from a container of liquid or from a wet
film or coating spilled or applied instantaneously
to a surface
4.3.1
4.3.1
4.3.1
4.3.2
4.4.2
4.4.2
4.4.2
4.4.2
6.2.2
6.2.2
6.2.2
6.2.2
H
V/S
Inhalation of a chemical substance during its
evaporation from a wet film or coating applied
to a surface, in which the period of application
is more than a few minutes
4.3.2
4.4.3
6.2.2
Inhalation of a chemical substance released from
a solid that sublimes (e.g., from solid room
deodorizer, moth balls, etc.)
Inhalation of a chemical substance released from
a dry coating or polymer
4.3.1
4.3.3
4.4.2
4.4.2
6.2.2
6.2.2
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Table 5. Sections of Volume 7 to Use in Estimating
Exposure via Dermal Contact with and
Ingestion of Consumer Products
Estimate levels to
which consumers are
Exposure pathway exposed
Exposure to a film of liquid deposited 6.2.3(1)
on the skin
Exposure to dusts and powders deposited on 6.2.3(2)
the skin
Dermal exposure to chemical substances 6.2.3(3)
contained in or adhering to solid matrices
Ingestion exposure to chemical substances 6.2.4(1)
leached out of objects designed to be
used in the mouth
Ingestion exposure from unintentionally 6.2.4(2)
swallowing liquids used in the mouth
14
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2. PHYSICAL-CHEMICAL PROPERTIES
One of the Initial efforts in any exposure assessment for a chemical
substance is identification of its physical-chemical properties.
Physical-chemical properties data are essential for a thorough
understanding or prediction of environmental fate (i.e., transport and
transformation) and the eventual environmental or exposure
concentrations. The mechanisms of release of a chemical substance from a
consumer product, the exposure media, and the exposure route are
determined by the chemical substance's properties. The purpose of this
section is to (1) briefly discuss properties that are relevant to
developing exposure assessments for chemicals in consumer products and
(2) catalog information sources for obtaining experimental property data
and methods for estimating properties where such data are lacking.
2,1 General Property Information
Table 6 summarizes the physical-chemical properties that are relevant
to performing exposure assessments for chemicals in consumer products.
Not all the properties listed are required for each chemical. Required
properties are dictated by the physical state of the chemical and the
physical-chemical nature of the consumer product that contains it. Many
of the properties listed may be required only when it is necessary to
estimate exposure concentrations based on chemical release algorithms.
The chemical release algorithms are discussed in Section 4 of this
document.
2.2 Data Gathering
The physical-chemical properties of a chemical substance can be
gathered from the scientific literature or, where experimental data are
lacking, they can be estimated. The following subsections discuss
sources of information for experimental data and methods for estimating
physical-chemical properties.
2.2.1 Sources of Experimental Data
Information sources from which experimental data can be gathered are
divided into those that are computer based and accessed on-line and those
that are published documents or "hard copy." The major on-line systems
including address, telephone, number, and contact for "help" information
are listed in Table 7. Published documents that summarize and present
experimental data are listed in Table 8.
Prior to initiating any data collection, the investigator should
obtain for the chemical substance of interest the Chemical Abstracts
15
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Table 6. Summary of Physical-Chemical Properties
Relevant to Consumer Exposure
Property/parameter
Units
Comments
Molecular weight
Dimensionless Required input for estimation of many other
properties. Required for stoichiometrically derived
chemical release estimates.
Physical state
Particle size
Density
Melting point/
boiling point
Solid, liquid, or gas.
exposure routes.
Assists in identification of
Length
(usually micron)
Mass/volume
(e.g., g/on3)
Degrees Celsius
Used for entrainment (dispersion) analysis of
dusts and powders and identifying area of
respiratory tract deposition.
Useful for calculating film thickness of liquids on
skin. Indicative of whether gases (or liquids) are
heavier or lighter than air (or water).
Input for calculating vapor pressure and volatili-
zation rates. Identifies physical state of
substance at ambient conditions.
Vapor pressure
Henry's law constant
mm Hg; torr;
atmospheres
Heat of vaporization Calories/mole
Dimensionless
or atm-m^/mol
Essential for predicting the behavior and fate of
chemicals in the environment: rates of evaporation,
equilibrium air concentrations (worst case).
Quantity of heat required to convert a unit mass of
liquid into a vapor without a rise in temperature.
Required input for estimating other properties such
as vapor pressure.
Indicative of a chemical's propensity to volatilize
from water. Required input for calculating
volatilization rates.
Solubility
Mass/volume
Maximum amount of the chemical that will dissolve in
pure liquid at a specified temperature. Facilitates
calculation of worst case concentrations. Required
input for calculating volatilization rates of
chemicals from solutions.
16
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Table 6. (continued)
Property/parameter
Units
Comments
Diffusion coefficients
(i.e., air, water,
solids)
Octanol /water
partitioning
coefficient
Volatilization rates
Lengths/time Indicative of a chemical's ability to move in a
(e.g., cm2/s) liquid, gas, or solid based on inter-molecular
collisions (not turbulence or bulk transport).
Diffusion coefficients through gas range from 10"
to 10~2 cm^/s; through liquids from 1(H> to
10-6 crn^/s; and through solids from 10~7 to
10-20 cn£/s. Required input for calculating
volatilization rates and migration through solid
matri ces.
Dimensionless
Length/time
(e.g., cm/hr)
Activity coefficient Dimensionless
Ratio of a chemical's concentration in the octanol
phase to its concentration in the aqueous (water)
phase. Important indicator of a chemical's fate.
Required for estimating air concentrations of
chemicals evaporating from liquids and solids.
A factor for compensating for non-ideal behavior of
compounds in solution. Required input for
estimating properties of mixtures.
17
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Table 7. Major Computerized Data Bases for Obtaining Physical-Chemical Properties
Data base name
Sponsor/contract support
Help information
Garments
Chemical Information System
(CIS)
HAZARDLINE
oo
Medical Literature Analysis
and Retrieval System
(MEDLARS)
Chemicals in Commerce
Information System (CICIS)
NIH/EPA Mike Keller
Computer Science Corp. 703-237-1333
P. 0. Box 2227 800-368-3432
Falls Church, VA 22042
Physicians World Communication Group Kay Sloves
Occupational Health Services, Inc. 800-223-8978
400 Plaza Drive
Secaucus, NO 07094
National Institutes of Health 301-496-6193
National Library of Medicine 800-638-8480
MEDLARS Management Section
8600 Rockville Pike
Bethesda, MD 20014
USEPA OTS/MSD-SDB Geri Nowak
Office of Toxic Substances 202-382-3568
Management Support Division
Washington, DC 20460
Access to a wealth of computerized information including
structure and nomenclature, chemical evaluation, clinical
toxicology, registry of toxic effects, and oil and hazardous
materials technical assistance data.
Access to environmental and occupational information on
hazardous substances including physical and chemical
properties, personal protective equipment, and medical
surveillance to test requirements, waste disposal and
leaks, spills, and fire fighting information.
On-line chemical dictionary access (CHEMLINE) and a wealth
of information on toxicology and bibliographic data on
chemical substances.
1977 TSCA Inventory of Chemical Substances. Chemical
properties, structures, production, and use.
Note: Data base has not been updated since 1977 and is
therefore somewhat out-of-date.
-------
Table 8. Major Published References for Obtaining
Physical-Chemical Properties
Document
Comment
CRC Handbook of Chemistry and Physics
Chemical Engineers Handbook
Lange's Handbook of Chemistry
The Merck Index
Kirk-Othmer Encyclopedia of Chemical
Technology
Farm Chemicals Handbook
Handbook of Environmental Data on Organic
Chemi cals
Good source for general properties of
a large variety of chemicals.
Good source for general properties of
a large variety of chemicals.
Good source for general properties of
a large variety of chemicals.
Good source for pharmaceutical or
medicinal chemical properties.
Good source for general properties
of a large variety of chemicals.
Good source for properties of farm
chemicals, particularly pesticides.
Good source for properties of organic
chemicals.
Physical Properties of Chemical Compounds
(Volumes I, II, III)
Physical Properties of Hydrocarbons
(Volumes I and II)
Cyclic, acyclic, and aliphatic
compounds.
Paraffinic, halogenated, and oxyge-
nated hydrocarbons (alcohols, oxides,
glycols) (Volume I); organic acids
ketones, aldehydes, ethers, esters
nitrogen compounds, aromatics, cyclic
hydrocarbons, and sulfur compounds
(Volume II).
The Aldrich Catalog - Handbook of Organic
and Biological Chemicals
Vapor Pressure of Organic Compounds
General properties of many organic
chemicals of environmental interest.
Good source for experimental vapor
pressure data.
19
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Table 8. (continued)
Document
Comment
Technical Data Book - Petroleum Refining
(Volumes I and II)
Handbook of Vapor Pressures and Heats of
Vaporization of Hydrocarbons and
Related Compounds
The Properties of Gases and Liquids
Faith, Keyes, and Clark, Industrial
Chemicals
Basic properties of organic compounds
that are petroleum derived.
Vapor pressure of hydrocarbons.
Covers most general properties.
General properties for a small number
of chemicals.
Publications of the National Bureau of
Standards (NBS); National Standard Data
Reference System (NSRDS)
- Journal of Physical and Chemical
Reference Data
- NSRDS - NBS publication series
- Miscellaneous technical society
publications
Publications of the Engineering Sciences
Data Units, Ltd. For example:
- Viscosity of liquid aliphatic
hydrocarbons: alkanes
- Thermal conductivity of liquid
carboxylic acids
- Heat capacity and enthalpy of
liquids: aliphatic alcohols
- Vapor pressures and critical points
of liquids. XIV: aliphatic oxygen-
nitrogen compounds
See Appendix A of Handbook of Chemical
Property Estimation Methods. Environ-
mental Behavior of Organic Chemicals
for additional information. NSRDS is
a good source for industrial process
data including information on thermo-
dynamic, transport, and physical
properties of industrial chemicals.
Information on ESDU and publications
can be obtained from:
ESDU
251-259 Regent Street
London WIR 7AD
England
20
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Service (CAS) number and synonyms for the name of the chemical
substance. Most current on-Hne data bases and published documents
catalog chemical data according to CAS number. This minimizes confusion
Inherent 1n storing and retrieving chemical data according to chemical
name since most chemicals have more than one name. The CAS number for a
chemical substance can be obtained from:
Toxic Substances Control Act Chemical Substances Inventory
Volumes I-IV (Initial Inventory, Cumulative Supplement, User
Guide and Indices to the Initial Inventory, and Trademarks and
Product Names)
U.S. Environmental Protection Agency
Office of Toxic Substances (TS-799)
Washington, DC 20460
Chemical name synonyms are particularly Important because consumer
product manufacturers frequently 11st consumer product chemical
formulations according to trade or generic chemical names. For example,
specific solvents 1n paints may simply be listed as "cellosolves" or
"glycols." A 11st of specific chemical names and generic names Is
extremely useful for securing physical-chemical property data and other
chemical use data related to consumer products. Many of the on-line data
bases and published documents found 1n Tables 7 and 8 include chemical
name synonyms.
2.2.2 Methods for Estimating Physical-Chemical Properties
Methods for estimating physical-chemical properties can also be found
1n on-line computerized data bases and 1n the published literature. The
on-line methods are those contained in EPA-OTS's Graphical Exposure
Modeling System (GEMS). Information on GEMS and inclusive data bases can
be obtained from GSC (1983) or by contacting the
Modeling Section
U.S. Environmental Protection Agency
Office of Toxic Substances (TS-798)
Washington, D.C. 20460
(202) 382-2256
Table 9 lists the chemical property estimation systems and methods
Included in GEMS, as well as published documents that contain additional
methods for estimating physical-chemical properties.
2.3 Summary
The functional steps in securing physical-chemical properties for a
chemical substance are summarized as follows:
21
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Table 9. Sources of Information for Estimating
Physical-Chemical Properties
Source/methods
Comment
Computerized systems
Graphical Exposure Modeling System (GEMS)
USEPA
Office of Toxic Substances
Chemical Fate Modeling Team
Washington, D.C. 20460
(202) 382-2256
(1) CHEMEST
- Solubility in water
- Soil absorption coefficient
- Bioconcentration factors for fish
- Activity coefficients
- Boiling point
- Vapor pressure
- Rate of volatilization from water
- Henry's law constant
(2) Molecular Structure File (S File)
(3) CLOGP (Log Kow - octanol/water
partition coefficient)
Published documents*
(1) Handbook of Chemical Property Estimation
Methods - Environmental Behavior of
Organic Compounds
- Octanol/water partition coefficient
- Solubility in water
- Solubility in various solvents
- Adsorption coefficient for soils
and sediments
- Bioconcentration factor in aquatic
organisms
- Acid dissociation constant
GEMS User's Guide.
CHEMEST User's Guide
(CHEMEST is a computerized
version of the procedures
listed below in Handbook of
Chemical Property Estimation
Methods - Environmental
Behavior of Organic
Compounds.)
SPILES User's Guide.
CLOGP User's Guide.
Not reconmended for fate
of chemicals via hydrolysis
and photolysis. See
documents listed below.
22
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Table 9. (continued)
Source/methods Comment
- Rate of hydrolysis
- Rate of aqueous photolysis
- Rate of biodegradation
- Atmospheric residence time
- Activity coefficient
- Boiling point
- Heat of vaporization
- Vapor pressure
- Volatilization from water
- Volatilization from soil
- Diffusion coefficients in air and water
- Flash points of pure substances
- Densities of vapors, liquids, and solids
- Surface tension
- Interfacial tension with water
- Liquid viscosity
- Heat capacity
- Thermal conductivity
- Dipole moment
- Index of refraction
(2) Structure Activity Correlations for
Environmental Reactions
- Rate of hydrolysis
- Rate of photolysis
- Rate of oxidation
- Rate of volatilization
- Absorption to sediment and soils
(3) Validation of Estimation Techniques for Supplemental data and
Predicting Environmental Transformation update of Structure
of Chemicals Activity Correlations
- Oxidation in water for Environmental
- Oxidation in air Reactions.
- Rate of hydrolysis
- Metal complexation
*Note: Documents listed are those principally used by EPA-OTS. The scientific
literature, much of it referenced in the above documents, includes a wealth
of background information and methods for estimating physical-chemical
properties.
23
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1. Obtain CAS number and compile list of chemical synonyms.
Tables 7 and 8 list information sources for obtaining CAS numbers
and synonyms.
2. Retrieve or gather experimental data for physical-chemical
properties of interest from on-line systems or published
documents. Table 7 lists computerized systems, and Table 8
cites published documents from which physical-chemical property
data can be obtained.
3. Where experimental data are lacking, estimate required properties
according to appropriate methods. Methods and systems for
estimating physical-chemical properties are listed in Table 9.
4. Summarize all data in tabular format, and clearly indicate all
units of measurement and sources of information including methods
used to estimate properties where experimental data were lacking.
Note: For each physical-chemical property of interest, all
immediately available data should be gathered. It is possible
that different isomers of a chemical substance may have vastly
differing property values. Property data-may also vary
because values were derived under different laboratory
conditions or controls; errors in experimental data are also
not uncommon. All property values gathered from the
experimental literature should be carefully reviewed and any
inconsistencies noted. Estimation techniques can be used to
help verify or resolve inconsistencies in experimental data.
24
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3. PRODUCT-SPECIFIC DATA REQUIRED TO ASSESS EXPOSURE
Prior to estimating the concentration of a chemical substance in an
external medium, the assessor should estimate the quantity of the
chemical released during use. In general, release of a chemical
substance to air from a consumer product can occur by three mechanisms:
1. Direct application to a surface, including skin.
2. Release of a chemical substance from pressurized aerosol products
and poured products that aerosolize releasing mists or
particulates.
3. Migration through the solid matrix of a consumer product and
subsequent volatilization or leaching.
The following sections discuss factors required to estimate the
amount of a chemical substance that can be released from a consumer
product during an exposure period. Methods for estimating the values of
these factors for specific products are also presented in the sections
that follow. Section 3.1 presents data for products that are applied as
liquid films, while Section 3.2 contains data for aerosol products.
Section 3.3 discusses sources that can be used to determine the presence
and the amounts of specific chemicals in consumer products. A generic
approach for determining weight fractions of specific chemicals in
consumer products is also presented in Section 3.3.
3.1 Amount of Chemical Substance Applied Directly to Surfaces
The amount of a chemical substance that is applied to a surface can
readily be estimated from the following product-specific data.
1. Surface area to which the consumer product is applied.
2. Surface area that a given amount of the consumer product can
cover (material consumption rate).
3. Density of the consumer product.
4. Weight fraction of the chemical substance in the product.
5. Surface area that can be covered by the consumer product in a
given amount of time (labor production rate).
25
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Sources of Information concerning material consumption rates Include
product labels and the Estimating Guide - 1982 published by the Painting
and Decorating Contractors of America (PDCA 1982). Material consumption
rates for a number of generic types of products are also reported In PDCA
(1982) and are differentiated according to: (1) method of application
(e.g., brush, roller); (2) type of surface to which the generic product
1s being applied (e.g., plywood, smooth siding, smooth finish plaster,
sandflnlsh plaster, concrete); (3) which coat 1s being applied (e.g.,
primer, first coat, second coat, third coat); and (4) type of sheen of
the product (e.g., flat finish, semi-gloss, gloss). Table 10 presents
material consumption rates 1n units of square feet per gallon for a
number of labor categories as reported In PDCA (1982). Table 11 presents
values for densities of selected products 1n units of grams per cubic
centimeter (g/cm-3) based on actual laboratory measurements of specific
name-brand products (Versar 1984c). Material consumption rates and
densities reported for generic types of products presumably differ very
little from material consumption rates and densities for specific
name-brand products within a given product group. Values for material
consumption rates and densities for specific brands can be used In place
of values for generic product types where generic product values are not
readily available. The converse situation also applies.
The following example Illustrates how surface area covered, material
consumption rate, product density, and weight fraction of a chemical
substance in a product can be used to determine the mass of a chemical
substance applied to a surface.
A table with surface area of 27 square feet Is covered with one
coat of varnish. Assuming a chemical substance comprises 5
percent by weight of the varnish, what mass of chemical substance
1s applied to the surface?
Divide the surface area covered by the material consumption rate
reported 1n Table 10 to obtain the number of gallons of varnish
required to cover the surface of the table,
27 ft2/600 ft2/gallon = .045 gallons
Multiply the number of gallons determined In Step 1 by the
density of varnish reported In Table 11 and by the factor for the
number of cm3 per gallon to obtain the number of grams of
product applied to the surface.
0.45 gallons x .879g/cm3 x 3785 cm3/gallon = 150 grams
26
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Table 10. Labor Production and Material Consumption Rates for Coatings
Applied to Surfaces by Labor Category and Method of Application
Labor category
Paint doors
Paint picture
mouldings, chair rails,
window frames, and other
trim up to 6-inch width
Paint windows
(no frame)
Stain
Shellac
Varnish
Lacquer
interior trim
Method of
application
Brush
Roller
Spray
Brush
Brush
Brush
Brush
Brush
Spray
Labor production
rate (ft2/hr)
125
275
400
200
150
220
200
175
250
Material consumption
rate (ft2/gallon)
400
400
300
1,000
450
500
600
600
275
Lacquer
interior doors and
cabi nets
Spray
275
250
Lacquer
interior panelling
Remove varnish with
liquid remover from a
flat surface
Remove paint with
liquid remover from a
flat surface
Wax and polish floors
Spray
450
45
30
200
250
180
175
1,080
27
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Table 10. (continued)
Labor category
Method of
application
Labor production
rate (ft2/hr)
Material consumption
rate (ft2/gallon)
Apply floor seal
to maple and pine
Apply floor seal to oak
Flat finish paint on Roller
plywood in a new residence
Flat finish paint on
smooth siding in a new
residence
Roller
400
450
350
325
500
500
300
300
Flat finish paint on
smooth finish plaster in
a new residence
Gloss/semi -gloss paint
on smooth finish plaster
in a new residence
Gloss/ semi -gloss paint
on sandfinish plaster
in a new residence
Latex flat finish paint
on smooth finish plaster
in a new residence
Latex flat finish paint
on rough finish plaster
in a new residence
Brush
Roller
Spray
Brush
Roller
Spray
Brush
Roller
Spray
Brush
Roller
Spray
Brush
Roller
Spray
245
325
500
260
350
550
150
275
400
225
340
475
175
265
475
500
475
550
500
475
550
295
280
320
400
380
440
300
285
325
Source: PDCA (1982).
28
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Table 11. Experimentally Determined Density Values for
Selected Consumer Products
Product . Density* (g/cm^)
Hinwax wood stain 0.800
Semi-gloss interior latex paint 1.168
Marine spar varnish 0.879
Polyurethane clear satin finish 0.866
Varathane plastic gloss paint 1.084
Anti-rust oil-based enamel paint 0.884
Furniture polish-lemon oil 0.834
Pure shellac 0.896
Gloss black enamel paint 0.903
Latex flat wall paint 1.240
Floor shine cleaner/wax 1.017
Fiberglass resin 1.106
Car wax finish restorer 1.017
Antique oil finish 0.832
High gloss car wax 1.022
Redwood latex stain 1.332
Carpenters wood glue 1.084
Floor deck enamel paint 1.067
Interior acrylic latex wall and trim paint 1.233
White interior ceiling paint 1.182
* At room temperature (~25°C).
Source: Versar (1984c).
29
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Multiply the weight fraction of chemical substance 1n the product
by the number of grams of product estimated to be applied to the
surface of the table (from step 2) to derive the mass of chemical
substance applied to the surface of the table.
150 grams x .05 =7.5 grams
To assess the amount of a chemical substance to which an Individual
may be exposed requires knowledge of the amount of a chemical substance
that may potentially enter an external medium from liquids or films
applied to a surface and of the duration of application of the product.
The period of application can be readily estimated from information
regarding the rate at which a specific product Is applied to a surface.
This rate, often referred to as the labor production rate, is reported
for a number of labor categories in PDCA (1982). Labor production rates
obtained from PDCA are presented in Table 10. Like the material
consumption rates shown in this table, the labor production rates are
also differentiated according to method of application, type of surface
to which the generic product is being applied, which coat is being
applied, and type of sheen of the product. Data regarding the time for
application of a product is not only useful for estimating the period of
active exposure, but is also useful in Itself as an Input for an
algorithm that predicts room air concentrations of a chemical substance
under conditions 1n which the release of the chemical is time-dependent
(see Section 4.4.3.).
The following example illustrates how the surface area covered and
the labor production rate can be used to estimate the duration of
application of a consumer product in the form of a liquid or film applied
to a surface.
The walls of a room 8 feet high, 8 feet wide, and 11 feet long (304
square feet) are covered with one coat of a flat finish paint using a
roller. Assuming the walls are of smooth siding, how long does it
take to apply the first coat?
Divide the value for the surface area of the walls of the room by the
labor production rate value from Table 10 reported for the first coat
of flat finish paint applied to smooth siding with a roller to obtain
the value for duration of application.
304 ft2 = .94 hours
325 ft2/hr
This duration accounts only for roller application. It excludes brush
painting of corners, moulding, and trim.
30
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3.2 Amount of a Chemical Substance Released by Use of Aerosol and
Pump Spray Products and by Pouring or Spilling Liquids and
Powders
Estimation of the amount of a chemical substance released from
consumer products that generate aerosols requires knowledge of the weight
fraction of chemical substance in the consumer product, the mass of
product released during the period of active use or active discharge, and
the fraction of product that does not contact its intended target.
Guidelines for determining the weight fraction of chemical substance in a
consumer product are presented in Section 3.4. Data on the mass of
product released during the period of actual discharge are needed for
scenarios in which products are discharged for only a few seconds
(instantaneously) during each exposure event. Data on the mass of
product released during the period of active use, however, are needed for
scenarios in which products are discharged for more than a few seconds
and for scenarios consisting of more than one active discharge, provided
each discharge occurs within short intervals of the other (e.g., on the
order of seconds).
Table 12 presents estimated ranges of values for-mass of product
released per use based on responses received from roughly 40 households
as part of an informal survey (Cote et al. 1974). The values shown in
Table 12 were derived from information provided on rate and frequency of
use by survey respondents. Rates of use were estimated from the numbers
and sizes of containers which the respondents reported using over a given
period of time. Cote et al. (1974) note that they have less confidence
in the value reported for oven cleaner than for other products because
oven cleaner is used infrequently and, therefore, the raw data used to
derive these estimates were not as plentiful.
Aerosol that does not contact its intended target is referred to as
overspray. The amount of overspray that occurs during application is a
function of the pressure exerted on the contents of the container and the
size of the orifice through which the contents are discharged, the size
and shape of the target, and the size of the particles composing the
spray. No specific information on values for overspray for aerosol
consumer products has been found. Estimates of paint loss, or overspray,
during application, however, are available for several methods of
application (Gross 1970). These estimates are presented in Table 13.
Conventional air spray systems atomize the paint fluid by intersecting
jets of compressed air (Gross 1970). Airless or hydraulic spray systems
atomize paint by the sudden release of high pressure as the fluid is
ejected through a small orifice (Gross 1970). Electrostatic spray
systems atomize fluids through the application of high voltage static
electricity as the paint flows off a sharp edge or point (Gross 1970).
. 31
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Table 12. Mass of Aerosol Product Released Per Use
Aerosol product Mass (grams/use)
Deodorant spray 2.5 - 3.0
Hair spray 7.0 - 9.3
Shaving foam 3.0 - 4.0
Air freshener 7.0 - 14.0
Disinfectant 9.4
Furniture polish 14.0
Dust spray 7.0 - 14.0
Oven cleaner 200 - 250
Source: Cote et al. (1974).
32
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Table 13. Estimates of Overspray During Application
Method of application Overspray fraction
Conventional air spraying .20 - .40
Airless spraying .10 - .20
Electrostatic spraying .05 - .15
Source: Gross (1970).
33
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Aerosol products used by consumers are discharged in a manner similar
to airless spray systems. For reasonable worst case estimates of
exposure to aerosol consumer products that are surface sprays
(e.g., spray paints), a value of 0.40 for fraction of overspray is
suggested. A value of 1.0 for fraction of overspray is suggested for
aerosol consumer products that are space sprays (e.g., air fresheners).
Additional effort is needed to obtain values for overspray fractions of
aerosol consumer products.
A recent study on aerosols formed during free-fall of liquids and
powders in static air (Sutter et al. 1982) reported that an average
weight fraction of 0.00003 of a "spilled" liquid and 0.00019 of a
"spilled" powder can be expected to become airborne in static air when
spilled from a height of one meter onto the floor of a room-sized
enclosure (Versar 1985). The mass of chemical substance unintentionally
released to air from accidental spills of liquids and powders can be
estimated by multiplying the value for fraction of material entrained in
air by the total mass of powder or liquid spilled and by the weight
fraction of chemical substance 1n the spilled product.
3.3 Identification of Consumer Products and Formulations
A key step in assessing consumer exposure is to identify the products
containing the chemical of interest. Identification of the consumer
products in which a particular chemical substance will appear directs the
exposure analyst to the appropriate exposure routes and relevant generic
scenarios necessary to calculate consumer exposure.
A chemical may appear in a consumer product as an ingredient or as a
residual (Impurity) of the product manufacturing process. Most of the
information sources presented in this section deal only with those
chemicals intentionally incorporated as an ingredient. Chemicals that
occur as impurities in consumer products are not as easily identified
through conventional sources; identification of such consumer products
will rely heavily on process engineering estimates and qualitative
estimates from knowledgeable contacts in the subject industries.
The information sources found most useful for identifying pertinent
consumer products are listed below.
Clinical Toxicology of Commercial Products (CTCP)
Consumer Product Safety Commission (CPSC) - economic analysis
Organic Chemical Producers Data Base (USEPA)
34
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Literature:
- The Merck Index
- The Condensed Chemical Dictionary
- K1rk-0thmer Encyclopedia of Chemical Technology. 3rd edition.
- The weekly Chemical Marketing Reporter
Once the consumer products are Identified, the typical amount of
chemical found in each product 1s determined. This formulation
Information satisfies the weight percent (WF) parameter used In the
exposure calculation (discussed 1n Section 6). The Information sources
found most useful 1n determining product formulations are:
Clinical Toxicology of Commercial Products (CTCP)
Consumer Product Safety Commission (CPSC) - CHIP Data Base
The Chemical Formulary (Chemical Publishing Co.)
Independent Investigation:
- Related patent literature
- Industry and trade association contact
- Spot surveys of products currently on shelf
- Literature (product- or brand-specific)
Clinical Toxicology of Commercial Products. 4th edition, (Gosselln
et al. (1984) Williams and Wllklns Co., Baltimore, MD), Is by far the
most useful resource with regard to product coverage and detail of
product formulations. CTCP 1s kept up-to-date on a computerized format
(available to Chemical Information System, CIS-USEPA, subscribers) and
has the advantage of allowing search by chemical constituent, product
name, product use, manufacturer, and other criteria.
The Chemical Formulary, by H. Bennett (Chemical Publishing Co., Inc.,
NY), 1s a valuable complement to CTCP 1n the determination of
formulations for a variety of consumer products. The 23 volumes of The
Chemical Formulary (from 1933 to 1981) represent a vast collection of
commercial formulas, which Include exact amounts and percentages of
constituent chemicals and notes on preparative techniques. Complete or
partial sets of volumes are available 1n select professional and public
libraries 1n the Washington, D.C., area.
The Economics Division of the Consumer Product Safety Commission
Investigates the occurrence of selected chemicals In consumer products.
In Its evaluations, CPSC uses many of the same tools mentioned above;
35
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however, 1t also Identifies consumer products and their formulations
through economic analyses and CPSC's CHIP data base. The CHIP data base
Is an 1n-house, on-Hne system developed from various resources collected
by CPSC. Some of CHIP'S components are: (1) CTCP (discussed above);
(2) elements from the NIOSH trade name Ingredient data base, which
contains formulations of Industrial, commercial, and consumer products.
(This data base 1s being updated; estimated availability 1s September
1985.) Existing data are limited and largely out-of-date. Contact Is
Mr. David Sundln, NIOSH, Cincinnati, Ohio, 513-684-4491); (3) some
occupational chemical exposure data (of unknown origin); (4) formulation
data for some drugs and cosmetics collected from the FDA; and
(5) consumer product formulation data compiled Independently by a CPSC
contractor (Auerbach) 1n 1975. After CPSC makes their evaluation for a
particular chemical substance (based on Its economic analysis, CHIP
results, and Independent field Investigation), the results are kept on
file. These files (by chemical) can provide Information and data found
nowhere else 1n the literature and are considered a primary resource to
this phase of the exposure assessment. Non-proprietary portions of the
file for a particular chemical can be retrieved through a freedom of
Information request to:
The Freedom of Information Officer
Office of the Secretary
Consumer Product Safety Commission
Washington, DC 20207
The remainder of the sources for product identification and
formulation are more commonly available data or reference tools that do
not provide consumer product or formulation Information as their primary
function. Such resources are generally used to identify consumer
products that may contain the chemical in question. The presence of the
chemical may be verified through other resources (usually manufacturers,
trade associations, or laboratory analysis).
The availability of information regarding the weight fraction of a
specific chemical in a consumer product varies with the chemical and the
consumer product, and can also be a function of the time and resources
available to the assessor. In some Instances, time and resources will
not allow an assessor to thoroughly investigate the sources useful in
determining formulations for products identified as containing the
chemical of interest. In such cases, a generic approach to determining
weight fractions of chemical substances in consumer products is
suggested. The first step of the generic approach is for the assessor to
ascertain the function of the chemical substance in the consumer product
for which weight fraction information is being sought. Once the function
is known, the assessor can refer to readily available resources for
information regarding the weight fraction of the functional component in
36
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the consumer product. An unpublished source of Information that Includes
this type of data 1s Standard Scenarios for Estimating Exposure to
Chemical Substances During Use of Consumer Products (Versar 1986).
Tables 14 through 19 present data on weight fractions of general
components of six selected consumer products as presented in Versar
(1986).
37
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Table 14. List of Functional Components as Weight
Fraction in Latex Wall Paint
Functional component
Weight fraction
in product
Examples
Binder
Thinner
Vehicle
Pigment
Extender pigment/
inert filler
Coalescing solvent
Plasticizer
Freeze-thaw stabilizer
Surfactant
Defoamer
Dispersing/Emulsifying
agent
Preservative
.10-.25
.25-.60
0-.10
.10-.20
.20-.55
.002-.02a
0-.0033
0-.02b
.0004-.002a
.002-.005a
.005-.012a
.0002-.0025a
Polyvinyl acetate, acrylic,
and/or styrene butadiene
elastomers
Water
Vegetable oil; resin
Titanium dioxide
Calcium carbonate;
alumino silicate
Ethers or ether esters of
ethylene or propylene glycol
Adi pates; phthalate esters
Ethylene and/or propylene
glycol
Sulfosuccinates
Aliphatic hydrocarbons and
fatty acid ester mixtures
Carboxylic acid salts;
trialkyltin fluoride
SuIfones; mercury
compounds
aThe range of values for weight fraction for this functional component were derived
from information on formulas reported for latex flat wall paint in JRB (1982).
^According to Gosselin (1984), latex wall paint can contain up to 2 percent ethylene
glycol; the specific function(s) of ethylene glycol in latex wall paint was not,
however, reported. Schurr (1981) reports that ethylene and propylene glycols are used
as freeze-thaw stabilizers and as slow-evaporating solvents. The range reported here
is based on the assumption that ethylene glycol is functioning only as a freeze-thaw
stabilizer.
Sources: Flick (1982)
Gosselin et al. (1984)
JRB (1982a)
JRB (1983a)
Schurr (1981). 33
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Table 15. List of Functional Components as Weight
Fraction in Aerosol Furniture Polish
Functional
components
Weight
fraction
Examples
Film-forming
ingredients
Film-forming
ingredients
Film-forming
ingredients
Emulsifiers
Sol vent
Odor-Formi ng
ingredients
Preservative
Propellants
- Compressed gas
- Compressed liquid
Carrier
Refractive index
modifier
0 - .05
0 - .04
0 - .02
.01 - .03
0.0 - .30
.0005 - .003
.0005 - .002
.01 - .02
.04 - .15
.40 - .90
0 - .05
Natural/synthetic waxes
Silicone oils
Mineral oils
Surfactants
Petroleum or synthetic
napthas, aliphatic
hydrocarbons
Essential oils, perfumes
Fungicides, bacteriocides
Nitrous oxide
Hydrocarbons
Water
Natural/synthetic waxes,
resins
Sources: Gosselin (1984)
ORB (1983b)
Randall and Dwyer (1982).
39
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Table 16. List of Functional Components as Weight Fraction
in All-Purpose Liquid Cleaner*
Functional component
Weight fraction
in product
Examples
Carrier Up to .96
Cleaning agent (includes
surfactants, detergents,
foamants) .03 - .32
Builder** Trace - .33
Abrasive .10 - .15
Dispersing agents .01 - .24
Emulsifying agents .01 - .04
Wetting agent .01 - .04
Ammonia .01
Opacifier .01
Fragrance .01
Color agent Trace - .01
Disinfectant/deodorizer .01 - .07
Stabi1i zer Trace
Water softener ?
Water
Sodium carbonates,
alkyl sulfates
Complex phosphates
Calcium carbonate
Quaternary ammonium
compounds
Sulfated fats and
oils
Dialkyl
sulfosuccinates
Pine oil
Anti-streaking
agent, film reducer
Sources: USEPA (1984); JRB (1982b)
* Best characterized by its use on indoor household surfaces (e.g.
countertops, floors, appliances).
** Upgrades cleaning efficiency of surfactants (JRB 1982a).
40
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Table 17. List of Functional Components as
Weight Fraction in Motor Oil
Functional
components
Weight
fraction
Examples
Petroleum lubricating 0.75 - 1.00
oil or basestock
Oi spersant
Detergent
Oxidation/corrosion
inhibitor
Anti-rust agent
Viscosity index
improver
Anti-foam agents
0.03 - 0.05A
0.025 - 0.05A
0.01 - 0.02A
0-0.10
0.02 - 0.20*
0 - trace'
,B
Pour-point depressants 0 - 0.05
Paraffinic, aromatic, and/or
alicyclic (naphthenic)
components
Polymeric succinimides;
olefin^Sg reaction
products; polyesters;
benzylamides
Barium sulfonate; calcium
sulfonate; magnesium sulfonate;
barium phenate; calcium
phenate; phenol sulfides;
barium phosphonates
Zinc dithiophosphates; barium
dithiophosphates; calcium
dithiophosphates
Amine succinates; aklaline
earth sulfonates
Methacrylate polymers;
aerylate polymers; olefin
polymers and copolymers;
styrene-butadiene copolymers;
pol y i sobuty 1 enes;
poly-alky1styrenes
Silicone polymers
Alkylarcmatic polymers;
polymethacry1ates
41
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Table 17. (Continued)
Functional
components
Weight
fraction
Examples
Extreme-pressure agents 0 - 0.01
Anti-wear additives
0 - 0.01
Compounds containing sulfur,
chlorine, or phosphorous alone
or in combination
Fatty acids; esters; ketones;
organic chlorine compounds;
organic sulfur compounds;
organic phosphorus compounds;
organic lead compounds
Sources: Booser (1981)
Wills (1980)
Gosselin et al. (1984).
ADave Pavlich, Lubrizol Corporation, (216) 943-4200; personal
communication with 0. Arrenholz, Versar Inc., May 22, 1986.
BTrace amounts are considered to be no more than a few
ppm.
42
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Table 18. Weight Fractions of Functional Components -
Floor Wax/Polish
Functional component
Weight fraction
Examples
Carrier
Cleaning ingredients/
surfactants/emuls i f i ers
Coalescing agents
Fugitive ligand complex
Film-forming ingredients
Minimum film-forming
temperature (MFT)
modifier
Preservatives
Refractive index modifier
Solvents
Viscosity modifiers
Colorant
0 - 0.88 Water
0 - 0.084 Ammonium hydroxide, morpholine,
alkyl phenyl ethoxylates,
potassium hydroxide, ammonia,
di ethyl ami noethanol
0 - 0.04 Glycol ether and derivatives,
zinc octoate
0 - 0.0029 Zinc octoate
0.05 - 0.96 Acrylic copolymer, styrene
copolymer, natural and
synthetic resins, waxes, tall
oil fatty acid, polyethylene
emulsion
0 - 0.0703 Glycol ether and derivatives,
plasticizers, ethylene glycol,
tall oil fatty acid, dibutyl
phthalate, tributoxyethyl
phosphate
0 - 0.0032 Phenyl mercuric acetate,
sodium metabisulfite
0 - 0.39
0 - 1.0
0-0.19
0 - trace
Resins, waxes
Mineral spirits, diethylene
glycol monoethyl ether,
diethylene glycol monomethyl
ether, petroleum distillate
Resins
Source: Gosselin et al. (1984), Flick (1984), JRB (1983b).
43
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Table 19. Functional Components as Weight Fraction in
Vinyl Upholstery Cleaners
Functional Component
Weight fraction
Examples
Carrier
Cleaning agent
Coalescing agents
MFT Modifier
Propel!ant
Solvent
Surfactants
0.67 - 0.84 Water, Isopropyl alcohol
0 - 0.002 Nitrous acid, sodium salt
(corrosive inhibitor); Soaps
0.05 - 0.053 Diethylene glycol monoethyl
ether; Dimethyl polysiloxane
fluid; 2-butoxyethanol;
Polyethylene, Mono
(p-(l, 1,3,3-tetramethyl-butyl)
phenyl) ether glycols;
Propylene glycol methyl
ethers; Polyglycol ether.
Film forming ingredients 0 - >0.02
Odor forming ingredients 0 - 0.01
Carboxyvinyl polymer, Fatty
acid.
0.05 - <0.06 Diethylene glycol monoethyl
ether; Fatty acid;
Triethanolamine; 2-butoxy-
ethanol ; Polyethylene, mono
(p-(l,1,3,3-tetramethyl-butyl)
phenyl) ether glycols;
Propylene glycol methyl
ether; Polyglycol ether.
Amyl acetate, Lemon perfume
oil, Perfume.
0 - 0.08 Propane, Isobutane
0.04 - 0.19 Odorless mineral spirits;
Isopropyl alcohol; Amyl
acetate.
0 - 0.10 Nonionic surfactant; Nonionic
nonyl phenoxypoly
(ethyleneoxy) ethanol
surfactant; Polyoxyethylene
alcohol surfactant;
Triethanolamine.
Sources: Battelle (1977); ORB (1983b); Gosselin et al. (1984); CIS (1986).
44
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sT^
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Instantaneous release 1s a single discharge of the contents of a
pressurized aerosol product for a period of a few seconds or less.
Continuous releases - generally long-term releases of a chemical
substance from a consumer product to an exposure medium. An
example of a continuous release 1s the discharge of the contents
of a pressurized aerosol product several times, where the
Intervals of time between the discharge are on the order of a few
seconds.
Time-dependent releases - generally long-term volatilization of a
chemical substance from a consumer product applied to a surface.
The time required to apply the product to the surface 1s more than
a few minutes. Therefore, the rate of application of the product
to the surface affects the total mass of chemical substance
available for release from a given area of surface at any point 1n
time during exposure. An example of a time-dependent release Is
the volatil- 1zat1on of a chemical substance from a film or
coating applied to a surface at a constant rate, where the period
of application 1s more than a couple of minutes.
Mechanisms Included 1n each of these groups are discussed 1n
Section 4.1.1. Factors affecting dispersal of a chemical in an exposure
medium and the resulting exposure concentrations are reviewed 1n
Section 4.1.2.
4.1.1 Chemical Release Mechanisms
Release or mass transfer of a chemical from a consumer product can be
thought of as the migration of the chemical in a mixture, either within
the same phase (e.g., dispersion of a vapor in air), or from phase to
phase (e.g., liquid to gas). The chemical 1n the consumer product may be
either a direct additive or a residual contaminant. Mass transfer occurs
by diffusion, where the driving force is based on the phenomenon that
systems not in equilibrium will tend to move toward equilibrium. There
are actually two types of diffusion processes: molecular diffusion and
eddy diffusion. In both cases, diffusion occurs as a result of a
concentration gradient; however, in eddy diffusion, the mass transfer is
greatly aided by the dynamic characteristics of air turbulence (Welty
et al. 1976).
Models describing mass transfer and concentration changes in the
consumer environment are based on a number of simple physical laws.
These include Dalton's Law, Raoult's Law, Henry's Law, Graham's Law, the
Ideal Gas Law, and Pick's Law. A general knowledge of these laws helps
the investigator to fully understand chemical release processes and
models. A review of these laws is presented in Volume 12 and Volume 11
of Methods for Assessing Exposure to Chemical Substances.
46
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Instantaneous chemical releases to air Include aerosolization and
dust entrapment or suspension. Examples of each process include the
spraying '(e.g., either pressurized or by pump) of a cleaner in the home
and the air suspension of soap powders poured from a container. A brief
description of each is as follows:
Aerosolization: Aerosols are particles or droplets, ranging in
size from about 0.15 to 5 microns, which are suspended or
dispersed in a gaseous medium such as air (Sciarra and Stoller
1974). . The phenomenon of aerosolization is related to the
expenditure of energy for the propulsion or agitation of a
liquid. Movement of the aerosol is initially controlled by the
expenditure of energy, and thereafter, by the processes of
molecular and eddy diffusion, depending upon the aerosol size.
Entrainment: The suspension and movement of particulates are also
controlled by energy (i.e., energy of agitation and/or dynamics of
air flow); the aerodynamic behavior of particles is determined by
particle size, shape, and density. The size, shape, and density
of the particulate affects settling by dictating the extent to
which gravity pulls the particle.
Continuous and time-dependent chemical releases may involve the mass
transfer of a chemical substance across phase boundaries. Processes
relevant to consumer exposure include volatilization of chemical
substances to air from liquids or solids and leaching from solids to
liquids. Migration via molecular diffusion controls the rate of movement
of a chemical to a phase boundary. (The term migration is used here only
to describe the movement of a chemical within a solid (e.g., a polymer).)
Following is a brief review of the processes of volatilization, leaching,
and migration:
Volatilization - The process by which a chemical transfers into
the vapor phase from a solid or liquid. Examples include the
release of constituents from paints, cleaning solutions, and
plastic materials.
Leaching - This term will be used to refer to the release of a
chemical from a solid to a liquid, for example, the leaching of
chemicals from food containers (e.g., plastic, cardboard) to the
enclosed food. Leaching rates are controlled by the migration of
the chemical to the surface of the solid and the solubilities of
the chemical in the two media.
Migration - This term will be used to refer to the movement of a
chemical within a solid matrix to the surface of a solid. For
consumer products, this process is generally only considered for
the movement of relatively low molecular weight substances from
47
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polymers (e.g., plastic and elastomeMc materials). Molecular
diffusion usually controls the rate of migration. The diffusion
rate of a compound is affected by the size of the molecule, the
structure and characteristics of the surrounding matrix, and the
attractive forces of the matrix constituents. The migration
phenomenon within polymer matrices is described in detail in
Volume 11 of Methods for Assessing Exposure to Chemical Substances.
Models or algorithms and required input parameters for estimating the
above types of mass transfer rates are reviewed in Section 4.3.
4.1.2 Factors Affecting Exposure Concentrations
Once a chemical is released into a medium (e.g., air, water) or to a
surface to which exposure may occur, a number of environmental factors
affect the concentration of the chemical in the media or on the surface.
These factors include the medium volume, surface area, room ventilation
rate, and mixing factor. Each of these is briefly described below:
Volume - This refers to the amount of air or liquid into which
the chemical is released. For chemicals emitted to air, this
generally refers to the room volume.
Surface Area - This factor is included in scenarios where coatings
are applied, spilled, or sprayed onto surfaces. A quantitative
value for the area of a surface covered by a consumer product is
needed to estimate several parameters required to assess
exposure. These include duration of application of a consumer
product in the form of a film or coating applied to a surface,
mass of chemical substance applied to a surface, and release rates
for volatile chemical substances (e.g., solvents) in films or
coatings applied to surfaces. As the area of surface covered by a
film or coating increases, the mass of chemical substance on the
surface increases, the amount of chemical substance released to
air from the film or coating on the surface increases, and the
resulting concentration of the chemical substance in air increases.
Ventilation Rate - Air ventilation effectively reduces the concen-
tration of a chemical substance released to indoor air by diluting
the chemical. The ventilation rate, therefore, is important for
calculating concentrations of chemicals in indoor air. This is
usually expressed in terms of an air exchange rate, which is
defined as the rate at which indoor air is replaced by outdoor
air. Generic ventilation rates for various building types or
rooms are discussed in Section 4.4. Ventilation rates are also
discussed in Volume 12 of Methods for Assessing Exposure to
Chemical Substances.
48
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Mixing Factor - The mixing factor, m, is an empirical number
that accounts for room-specific effects on transport of chemical
substances (Repace and Lowrey 1980). Removal of chemical sub-
stances is more rapid in a well-mixed atmosphere than in a poorly
mixed, stable one. Factors that affect the mixing factor include
type and placement of ventilation grills, ventilation flow rates,
inhomogeneous distribution of a chemical substance in a room,
physical barriers, circulation fans, and room traffic (Repace and
Lowrey 1980). A mixing factor of 1 means that the room has ideal,
perfect mixing. Actual values usually range from 1/2 to 1/10
(Repace and Lowrey 1980).
Models or algorithms including required input parameters and generic data
for calculating exposure concentrations are discussed in Section 4.4.
4.2 Monitoring Data
The most accurate method of estimating exposure to a chemical sub-
stance is via the use of monitoring data for the chemical in the media
of concern throughout the duration of exposure. Initial efforts in a
consumer exposure assessment, therefore, should focus on gathering all
available monitoring data, including the following:
Indoor air concentrations
Surface concentrations
Concentrations in consumer products of contaminants of interest.
Currently, there is no automated data base or repository for any of
these types of data. However, indoor air data have been found in
independent scientific studies through a computer search of the
scientific literature (e.g., chemical abstracts, NTIS holdings, and other
bibliographic files such as those in the DIALOG Information Retrieval
Service).
The Department of Energy and the CPSC sponsored a successful pilot
research study of selected indoor air pollutants from which development
of a more extensive data base is planned. Studies included monitoring of
highly volatile organics such as benzene, halogenated hydrocarbons, other
chemicals released from plastics and resins, and data on environmental
factors, such as air exchange rate, temperature, and humidity of indoor
environments sampled. In general, however, assessment of exposure to
chemicals in consumer products must rely primarily upon the estimation
procedures, models, or algorithms discussed below.
4.3 Methods to Estimate Release of Chemical Substances from Consumer
Products
The release rate is a key parameter required to estimate the
concentration of a chemical substance in an exposure medium as a result
49
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of a continuous or time-dependent release. The factors that determine
the release rate of a chemical substance from a product vary depending
upon whether the release is continuous or time-dependent. These factors
also differ for releases of chemical substances from (1) pressurized
aerosol products; (2) liquid films on surfaces; and (3) bulk liquids and
solids. More than one mechanism of release may be applicable for a given
consumer product. For example, to account for all the release mechanisms
occurring as a result of spray painting the walls of a room, one must
consider (1) the rate at which the chemical substance is being discharged
from the container; (2) the rate at which the chemical substance
volatilizes from the liquid paint film applied to the surface of the
wall; and (3) the rate at which the chemical substance migrates through
the film that forms once the paint has dried.
4.3.1 Release Rate of Chemical Substances in Aerosol Consumer Products
This method is recommended for estimating the continuous release rate
of the contents of a pressurized aerosol container to air. The
continuous release can consist of one continuous discharge of the
contents of a pressurized container or many discharges of the contents
during the period of active use, provided the discharges occur within
short intervals of one another (I.e., on the order of seconds). The
following equation is used to estimate the release rate of a chemical
substance from a pressurized aerosol product.
. WF x H x 0V ., ns
G- 55 (4-1)
where
WF = weight fraction of chemical substance in product (unitless)
G = release rate of chemical substance (mass/hr)
M = mass of product discharged during active use (units of mass)
0V = fraction of product that is overspray and does not contact
intended target (unitless)
DD = duration of active discharge of the pressurized aerosol product
(hours).
General guidelines for estimating the parameters of equation (4-1) are
presented in Section 3 of this volume.
If the product is designed to be released into air rather than
directed at a surface, the entire mass of product released may be
considered overspray, and the value for 0V may be set equal to one.
Products of this type include aerosol air fresheners, pesticide space
fumigants, and solid room deodorizers.
50
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If the contents of the pressurized aerosol product are applied to a
surface, release of a chemical substance 1n the product will occur via
two pathways: direct discharge to air with the contents of the aerosol
container and evaporation of the material deposited on the surface. .Much
of the overspray from direct discharge will be deposited on unintended
surfaces. The overspray, or portion of material that misses the intended
target, is the maximum amount of product that can be discharged directly
to air. Equation (4-1) is recommended only for estimating the continuous
release rate of a chemical substance via direct discharge to air. The
method for estimating the rate at which the chemical substance evaporates
from the material deposited on the surface is presented in the section
that follows.
4.3.2 Release Rate of Chemical Substances from Liquid Films Applied
to Surfaces
(1) Assumptions. The equations required to estimate the rate of
release of a chemical substance from a liquid film applied to a surface
differ for continuous and time-dependent releases. Rate of release will
be considered continuous if the liquid is instantaneously sprayed or
spilled onto the surface; otherwise, the release will be time-dependent
so that the rate at which the film is applied and the change in mass of
the chemical substance released from the surface with time as the film is
being applied are taken into account. For practical applications, it is
best to consider the release rate to be continuous if the liquid film is
instantaneously spilled or sprayed onto a surface or if the time required
to cover the surface with the liquid film is less than a few minutes. If
the time required to cover the surface with the liquid film is more than
a few minutes, it is best to consider the rate of release to be
time-dependent.
The difference between the continuous release rate and the time-
dependent release rate is as follows. For a scenario in which the
release rate is continuous, the amount of chemical substance remaining
on the surface is the same for each unit of area at any given point in
time. For a scenario in which the release rate is time-dependent,
however, the amount of chemical substance remaining on the surface is
different for each unit of area at any given point in time. The
difference between these two scenarios is the rate at which the film is
applied to the surface. For a scenario in which the release rate is
continuous, the film is instantaneously applied to the surface.
Therefore, the rate at which the film is applied is not a parameter of
concern. For a scenario in which the release rate is time-dependent,
however, the rate at which the film containing the volatile chemical
substance is applied affects the total mass of chemical substance
available for release from a given area at any point in time.
The following example illustrates the concept of a time-dependent
release. An individual paints a board that has a surface area of five
51
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square feet. The paint that Is ultimately applied to the board contains
five grams of a volatile chemical substance distributed evenly throughout
the paint applied to the board. In other words, the surface of the board
will be coated with one gram of the chemical substance for every square
foot of board. Assume that the time required for the chemical substance
to evaporate from the surface once it 1s applied is five minutes. Further
assume that the individual paints the board at a constant rate of one
square foot per minute. Therefore, the time required to apply the paint
to the board is five minutes. Figure 1 depicts the mass of volatile
chemical substance remaining on the surface for each square foot of board
as a function of time. Values for the cumulative mass of chemical
substance applied, the cumulative mass remaining on the surface of the
board, and the cumulative mass released to air are also presented for
each minute after painting is initiated. Values for the mass released
to air during each minute are shown as well.
It must be noted that, for this Illustration, instantaneous appli-
cation of coating to a surface area of one square foot was assumed at
each minute during application. In theory, each square foot could be"
divided into any number of units and could be analyzed in the same way
as the five square foot board used in this example. The foundation of
the time-dependent release is the assumption of instantaneous application
of coating to some fixed area of the total surface and initiation of
chemical release at a constant rate at the Instant the application is
completed. The accuracy of values predicted for the mass remaining and
for the mass released using the time-dependent release rate increases
with decreasing size of area assumed to be Instantaneously coated. For
the purpose of assessing consumer exposure to chemical substances
volatilizing from coatings applied to surfaces, the surface area
determined to be painted in one minute can probably be assumed to be
coated instantaneously.
(2) Equations. The following equation is used to estimate the
release rate of a chemical substance for those scenarios in which the
assumption of a continuous rate of release is applicable.
where
G =
N =
SA =
MW =
N x SA x MW x 3600
release rate of chemical substance (grams/hr)
molar flux of pure chemical substance (mole/cm2-sec)
surface area covered by liquid film (cm2)
molecular weight of chemical substance (g/mole).
(4-2)
Equation (4-5) is used to estimate the release rate of a chemical
substance for those scenarios in which the assumption of a time-dependent
52
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TIME DEPENDENT RELEASE
CAj
M
0.8
14
0.6
0.8
Mf
M
0.6
M
1.8
M
M.
*:-
4l
Vs -S^:
'Mil
ifr
JHL*.
*'i"V">W
-'Mfv
«.'*"'
;₯:
**;-"-, , '
' > ..
TIME ELAPSED
^' "
!^'
"t- VJ '
M>
AFTER PAINTING
IS INITIATED
(MINUTES) 12 3456789 10
CUMULATIVE
MASS APPLIED
(GRAMS) 1.0 2.0 3.0 4.0 5.0
CUMULATIVE
MASS REMAINING
ON SURFACE
(GRAMS) 1.0
CUMULATIVE
MASS RELEASED
TO AIR (GRAMS) 0.0
MASS RE LEASED
TO AIR DURING
EACH MINUTE
(GRAMS)
1.8
0.2
0.2
2.4
0.6
0.4
2.8
1.2
0.6
3.0
2.0
0.8
2.0
3.0
1.0
1.2
3.8
0.8
0.6
4.4
0.6
0.2
4.8
0.4
5.0
0.2
- SHADED BLOCK DENOTES VOLATILE
SUBSTANCE REMAINING ON SURFACE
FIGURE 1. MASS OF VOLATILE CHEMICAL SUBSTANCE REMAINING ON
SURFACE OF EACH SQUARE FOOT OF BOARp AS A FUNCTION
OF TIME :
-------
rate of release 1s applicable. Equation (4-5) is the product of
equations (4-3) and (4-4).
GN = N x MW x 3600 (4-3)
where
GN = Mass flux (g/cm2-hr).
Equation (4-4) is as follows:
AR = -&- (4-4)
where
AR = rate of application of film to the surface (cm2/hr)
SA = surface area covered (cm?)
ta = duration of application (hours).
The resulting equation, (4-5), is expressed below:
GNAR = N x MW x 3600 x (SA/ta) (4-5)
where
Gj\|AR = time-dependent release rate (g/hr2)
and the other variables in equation (4-5) are as defined previously.
The rate is expressed in units of mass/hr2 because the mass released
is changing with time. When this release rate is used in equations to
calculate indoor air concentrations resulting from a time-dependent
release situation, the resulting units of concentration are expressed in
the correct units (e.g., mass/volume).
Both the continuous and time-dependent release rates are a function
of the rate or molar flux of diffusion of a chemical substance, N,
expressed in moles/time-area. This rate is essentially the average flow
of the diffusing molecules per unit area (during diffusion) per unit
time. It depends not only on the concentration gradient, but also on the
characteristics of the diffusing compounds and on environmental parameters
(temperature, pressure, etc.). The following equation is used to calculate
the molar flux of a chemical substance.
-P x DAB x (PB2 - PB1)
N= LxRxTx "
54
-------
where
N = molar flux (mole/cm2-sec)
P = atmospheric pressure (atm)
°AB = diffusion coefficient of chemical substance in air at 25°C and
1 atmosphere (cm2/sec)
= partial pressure of chemical substance at interface of liquid
and gas film (atm)
= partial pressure of chemical substance at interface of gas
film and main air stream (atm)
L = gas film thickness (cm); (A value of 2.54 cm or 1 inch can be
assumed if no other information is available.)
R = gas constant, 82.05 atm-cm3/mole-°K
T = temperature (°K); (A value of 298°K or 25°C is usually
assumed to represent ambient conditions.).
Equation (4-7) is used to calculate the parameter, (P/\)lm, in
equation (4-6).
PA2 - PA1
(PA)lm = ,_,Drr: (4-7)
H/ Tn(pA2/pAl)
where
= partial pressure of air at Interface of gas film
and main air stream (atm)
= partial pressure of air at interface of liquid and
gas film (atm) .
The variables PA-| , P/^t PBI and PB2 mus't be determined
prior to calculating (P/\)lm and N. The partial pressures of a
two-component system form an integral part of the molar flux
calculations. In computing the partial pressures, one has to consider
the two Interfaces involved 1n the diffusion process. Diffusion is
controlled by the concentration gradient of B in a stagnant gas film on
the surface of the liquid film. Considering the liquid and air as the
two components of a system, the interfaces could be defined as (1) the
interface between the liquid and the gas film and (2) interface between
the gas film and the main air stream (Versar 1984b). A value of 1 atm
can be assumed for P^- The value of Pg2, usually assumed to be
zero, is calculated as follows:
PB2 = 1-PA2 (4-8)
where these variables are as previously defined. The value of PA-| is
calculated as follows:
55
-------
PAI - I-PBI
where these variables are as previously defined.
The following equation 1s used to calculate
VP
PB1 = ^ (4-10)
where
VP = the vapor pressure of the chemical substance at the desired
room temperature (mm Hg)
P = atmospheric pressure at the desired altitude (mm Hg); (e.g.,
P = 760 mm Hg at sea level).
The values R and T are as defined previously.
To calculate the molar flux, N, a value for the diffusion coeffi-
cient, DAB» °f the chemical substance in air under the appropriate
environmental conditions must be obtained. Use of experimentally
determined values 1s preferred 1f they are available for the chemical
substance being examined under the specific environmental conditions
under which exposure is occurring. In the absence of such data, the
Fuller, Schettler, and 61dd1ngs (FSG) method or the Wilke and Lee (WL)
method can be used to estimate the diffusion coefficients (Lyman et al.
1982). The FSG method 1s reportedly applicable to nonpolar gases at low
to moderate temperatures, and the WL method 1s applicable to a wide
range of compounds over a fairly wide temperature range. The WL method,
presented here, is preferred because the average number of errors
obtained with this method is considerably less than obtained with the
FSG method.
(0.00217 - 0.00050 Jl/M + 1/M R)T3/2 -v/l/M + 1/M
D. V - - - * - ^ - * - 2-
.R =
P "AB
where
DAB = diffusion coefficient (cm2/sec)
T = absolute temperature (°K)
, MB = molecular weight of air and chemical substance,
respectively
P = absolute pressure (atm)0
°/\B = characteristic length, A (Angstrom units)
Q = collision integral.
56
-------
The collision Integral, Q, 1s a function of the molecular energy of
attraction, c, and the Boltzmann Constant, kg, as given below:
a . -V ^ s " (4-12)
(T*)u exp (T*d) exp (T*f) exp (T*h)
where
the values a-h are as given 1n Chapter 17, Lyman et al. (1982), and
T* = T . (4-13)
V(e/KR). («/KR)R
' D H D D
Values of e/kg are given 1n Treybal (1968) for some of the more
common gases. Values for other gases can be approximated using the
following formula (Lyman et al. 1982):
e/kg = 1.15Tb (4-14)
where
Tfc = normal boiling point (°K).
The characteristic length, o^g, can be calculated using the
following relationship:
CA + °B
°AB = 3(4-15)
where
c/\ = 3.711 A (angstrom units)
OB = 1.18V'B1/3 (4-16)
'g = molar volume of the chemical substance at Its normal boiling
point (cm3/mole). (See Treybal (1968) or Lyman et al. (1982)
for atomic and molecular volumes.)
Fuller, Schettler, and Giddings (FSG) (1966) present a simplified
approach for calculating the diffusion coefficient, D^g. The method Is
applicable for nonpolar gases In air at low to moderate temperatures:
57
-------
DAB =
10
P
-3 T1.75 -
-------
Table 20. Diffusion Coefficients (@ 25°C and 1 atm)
for Selected Organic Chemicals in Air
Chemical
Hexane
Benzene
Toluene
Benzyl alcohol
Chlorobenzene
Nitrobenzene
Benzyl chloride
o-Chlorotoluene
m-Chlorotoluene
p-Chlorotoluene
Diethyl phthalate
Di butyl phthalate
Diisooctyl phthalate
Chlorofonn
Carbon tetrachloride
1 ,1-Dichloroethane
1 ,2-Dichloroethane
1 , 1 -Di ch 1 oroethyl ene
Vinyl chloride
1 , 1 , 1 -T r i ch 1 oroethane
1 , 1 , 2-T r i ch 1 oroethane
1 ,1 , 2, 2-Tetrachl oroethane
Trichl oroethyl ene
Tetrach 1 oroethyl ene
Pentach 1 oroethane
Hexach 1 orobenzene
Molecular
weight
86.17
78.11
92.13
108.13
112.56
123.11
126.58
126.58
126.58
126.58
222.23
278.34
390.56
119.39
153.84
98.97
98.97
96.95
62.50
133.42
133.42
167.86
131.40
165.85
202.31
284.80
Diffusion coefficient
(cn^/sec)
0.0732
0.0932
0.0849
0.0712
0.0747
0.0721
0.0713
0.0688
0.0645
0.0621
0.0497
0.0421
0.0377
0.0888
0.0828
0.0919
0.0907
0.1144
0.1225
0.0794
0.0792
0.0722
0.0875
0.0797
0.0673
0.12
Source: Schwope et al. (1985).
59
-------
exhibit a rate of evaporation different from that which 1t exhibits 1n
the pure state.
To adjust the release rate of the pure chemical to account for
non-Ideal behavior as a result of Interactions among mixture components
and to account for the effects of dilution of the mixture In water or
other solvents, the release rate of the pure chemical must be multiplied
by a correction factor. The correction factor-can be, In order of
preference, the activity coefficient, the mole fraction, or the weight
fraction of the chemical 1n the mixture from which It 1s evaporating.
Methods for estimating activity coefficients for two-component
systems are presented 1n the Handbook of Chemical Property Estimation
Methods (Lyman et al. 1982). Although the activity coefficient Is the
most accurate correction factor, the detailed data required regarding
components of the mixture and the length of time required to complete the
calculations are major disadvantages. The weight fraction of each
component of the mixture must be known. In addition, the activity
coefficient for each component with each of the other components of the
mixture must be obtained.
A simpler approach for obtaining the correction factor 1s to use the
mole fraction of the chemical in the mixture as a substitute for the
activity coefficient. The mole fraction, although less accurate than the
activity coefficient as a correction factor, is easier to calculate. To
calculate the mole fraction, the weight fraction and the molecular weight
of each component of the mixture must be known.
In the absence of data on the weight fraction and/or molecular weight
of each component of a mixture, it is suggested that the weight fraction
of the chemical substance in the mixture be used as a correction factor.
Use of the weight fraction as a correction factor provides the lowest
degree of accuracy of the three variables suggested. The major
advantage, however, 1s the ease with which a value for correction factor
can be obtained.
4.3.3 Chemical Release from Bulk Liquids and Solids
This method can be used to calculate release rates of chemical sub-
stances migrating through bulk liquids and solids. Applicable scenarios
include dermal contact with solid objects, contaminant release from
containers to food or liquids intended for consumption, release from open
containers of bulk liquids to air, and release from dry coatings and
solid objects to air.
The optimal way to determine the diffusion coefficient of a migrant
in a liquid or solid is experimentation. Schwope et al. (1985) present
experimentally determined diffusion coefficients for the diffusion of
60
-------
migrants through selected polymers as a function of the molecular weight
of the migrant. The diffusion coefficient through a specific polymer can
vary by several orders of magnitude depending on the molecular weight of
the migrant. The values of these diffusion coefficients range from
10~7 to ICh4 cm2/sec for migrant in silicone rubber, the most flexible
material discussed in Schwope et al. (1985), and from ICH7 to 10~7 cm2/sec
for migrant in unplasticized PVC, the most rigid material discussed in
this study. By comparison, the corresponding diffusion coefficients
through air range from 10~2 cm2/sec to 1(H cm2/sec (Schwope et al.
1985). D1ffusi.cn through the polymer is usually the rate controlling
step for migrant release.
Experimental data are not available for most migrant/polymer pairs.
Schwope et al. (1985) present an empirical approach to estimating the
diffusion coefficient of a migrant through a polymer, knowing only the
molecular weight of the migrant and the general type of polymer involved.
Diffusion coefficients for migrants in a water solution can be
estimated by the Wilke-Chang method (Reid et al. 1977) using the
following equation:
where
Dw = (7.4 x 10-8 (4>M)1/2 T)/nwVB
0.6
(4-18)
4> = solution association constant (2.26)
M = molecular weight of migrant
T = temperature (°K)
nw = viscosity of water in cp (1.002 at 20°C and 0.8904
at 25°C)
VB = molar volume of migrant at boiling point (cm3/g-mole).
At 20°C, diffusion coefficients for inorganic and organic migrants
in water typically range from 0.4 x 10-5 to 5 x 10-5 cm2/sec. A
listing of experimentally determined diffusion coefficients for selected
migrants in water is presented in Table 21.
Schwope et al. (1985) have developed a method for estimating the
fraction of total migrants released over a given time period when
diffusion through a polymer is the rate controlling step. The most
simplified version of the method is shown here; it assumes that the
external phase is well mixed and that it provides no resistance to
migrant release from the polymer. The method requires calculating two
dimensionless parameters, y and o, using equations (4-19) and (4-20),
respectively.
= Dt/L2
(4-19)
61
-------
Table 21. Diffusion Coefficients in Aqueous Solutions
at Infinite Dilution
Chemical
Hydrogen
Oxygen
Nitrogen
Nitrous oxide
Carbon dioxide
Anmonia
Methane
n-Butane
Propyl ene
Methyl cyclopentane
Benzene
Ethyl benzene
Methyl alcohol
Ethyl alcohol
Temperature
(°C)
25
25
29.6
29.6
25
25
12
2
20
60
4
20
60
25
2
10
20
60
2
10
20
60
2
10
20
60
15
10
15
25
Diffusion coefficient
in water (x 10"^)
(cmZ/s)
4.8
2.41
3.49
3.47
2.67
2.00
1.64
0.85
1.49
3.55
0.50
0.89
2.51
1.44
0.48
0.59
0.85
1.92
0.58
0.75
1.02
2.55
0.44
0.61
0.81
1.95
1.26
0.84
1.00
1.24
62
-------
Table 21. (continued)
Chemical
n-Propyl alcohol
Isoamyl alcohol
Allyl alcohol
Benzyl alcohol
Ethyl ene glycol
Glycerol
Acetic acid
Oxalic acid
Benzoi c acid
Ethyl acetate
Urea
Di ethyl ami ne
Acetonitrile
Aniline
Furfural
Pyridine
Vinyl chloride
Temperature
(°C)
15
15
15
20
20
25
40
55
70
15
20
20
25
20
20
25
20
15
20
20
15
25
50
75
Diffusion coefficient
in water (x 10~5)
(cm2/s)
0.87
0.69
0.90
0.82
1.04
1.16
1.71
2.26
2.75
0.72
1.19
1.53
1.21
1.00
1.20
1.38
0.97
1.26
0.92
1.04
0.58
1.34
2.42
3.67
Source: Schwope et al. (1985).
63
-------
where
D = diffusion coefficient of the migrant through the polymer
(cm^/sec)
t = time of release (seconds)
L = thickness of source (cm) in cases of one-sided exposure; in
cases of two-sided exposure use a value for L corresponding
to half the thickness of the source.
a = aK/L (4-20)
where
a = external phase volume divided by surface area of source (cm)
K = partition coefficient (dimensionless ratio of concentration
1n external phase volume to the concentration in source).
The calculated values of (p and a can be used with Figure 2 to
determine the fraction, F, of migrant which has been released from the
polymer at time, t. The fraction of migrant released at time, t, can
then be multiplied by the original concentration in the polymer and the
polymer volume to find the total mass of migrant released as follows:
Mt = F CSOVS (4-21)
where
M^- = mass of migrant released (g)
F = fraction of migrant released
Cso = original concentration in polymer (g/cm3)
Vs = volume of polymer (cm3).
The mass, Mt, should be divided by the time to get the average
release rate during the period. This release rate can be used in the
appropriate equations presented in Section 4.4.2 to calculate average
concentrations resulting from continuous releases.
Other methods of estimating release rates can also be found in
Schwope et al. (1985), including methods for estimating the rate of
migrant release from one phase to another, where diffusion through the
external phase or diffusion through a boundary layer is rate-controlling
or where partitioning between the polymer and external phase affects the
migration rate.
4.4 Methods for Estimating Concentrations in Indoor Air
The following subsections present equations used to estimate
concentrations of chemical substances to which consumers may be exposed
64
-------
CTl
tn
"iv=TT4 T-~I. ! ' i : ; . , i t > i
"~"'~~'"'
TmfrHT
10
to"
Source: Schwope et al. (1985).
Figure 2. Fraction migrated as a function oftyfor well-mixed domains.
-------
as a result of releases of chemical substances from consumer products to
room air. The equations presented for estimating the concentration at
any specified time during exposure and for estimating the average
concentration during the period of exposure are those used in the
Computerized Consumer Exposure Model (CCEM). These equations are
applicable to any situation in which release of the chemical substance
from the consumer product is to a volume of air that may be considered a
single compartment. Consequently, these equations are designed to
estimate concentrations 1n a single room containing a consumer product
that releases a chemical substance. These equations include no
parameters to account for the flow of air from one indoor compartment to
another. They are, therefore, not Intended to be applied to estimate
concentrations of chemical substances in rooms other than the room
containing the consumer product from which the chemical is released.
These equations are also not intended to be used to estimate average
concentrations of chemical substances in entire residences.
Multi-compartment models that take into account air flow patterns from
one indoor air compartment to another and for specific configurations of
the types of residences being considered (e.g., split-level home,
two-story home, rambler, office building) 1n addition to other applicable
parameters are more suitable for this purpose.
Releases of chemical substances from consumer products are
characterized in this methodology as Instantaneous releases, continuous
releases, or time-dependent releases. Appropriate equations for
estimating concentrations in indoor air are shown for each type of
release. The equations for estimating concentrations of chemical
substances in Indoor air as a result of continuous and time-dependent
releases are derived from equations for estimating concentrations
resulting from Instantaneous releases. A brief discussion of
concentrations resulting from instantaneous releases of chemical
substances is presented in Section 4.4.1. For details on the derivation
of equations for all types of releases, refer to Volume 12 of Methods for
Assessing Exposure to Chemical Substances. Equations presented for
estimating concentrations resulting from continuous releases of chemical
substances are used in the continuous release - aerosol and the
continuous release - film modules of CCEM. The continuous release -
aerosol module estimates concentrations for instantaneous and continuous
discharges from aerosol consumer products. Equations for estimating
concentrations resulting from time-dependent releases of chemical
substances are used in the time-dependent release module of CCEM.
Uniform distribution of the releases throughout the room is assumed for
instantaneous, continuous, and time-dependent releases.
In all three modules of CCEM, average concentrations can be
calculated for any interval of time after release of the chemical
occurs. The time at the beginning of exposure, t^, and the time at the
end of exposure, te, are used to specify the interval. If the time at
66
-------
the beginning of exposure 1s not specified, the time at the beginning of
exposure 1s assumed to be the time at the beginning of release, t0.
The time at the beginning of release 1s always zero. When specifying the
time at the beginning of exposure, a time cannot be selected that occurs
before release of the chemical begins (I.e., t^ must be greater than or
equal to t = 0, or t0). The time at the beginning of exposure must
also be less than the time at the end of exposure (e.g., t& must be
less than te).
In all three modules of CCEM, the duration of exposure does not have
to correspond to the Interval of time for which the average concentration
is estimated. For example, a chemical is released continuously from a
film on a surface for a period of 30 days. The receptor, however, is
only exposed to the chemical for a period of 8 hours per day. This
corresponds to one exposure event. In this case, the average
concentration would be estimated for the interval from t = 0 to
t = 720 hours (24 hours/day x 30 days). To calculate exposure, the
duration of exposure would be set equal to 8 hours per event and the
annual frequency of exposure would be set equal to 30 events per year.
4.4.1 Concentrations Resulting from Instantaneous Releases of Chemical
Substances
These methods are most applicable to exposure scenarios in which a
short-term release of a chemical substance occurs (e.g., on the order of
a few seconds). Examples include release of a chemical substance due to
a single discharge of product from an aerosol spray container or a spill
of a volatile liquid or fine powder. The basic criterion for classifying
a release as instantaneous is that the initial concentration, C0, is
the maximum concentration to which an individual 1s exposed and that the
concentration decreases and approaches zero as time progresses.
The following equation is used to estimate the concentration
resulting from an instantaneous release to indoor air at any time, t,
during a period of exposure (Porter 1983).
C = C0e-m(Q/v)t (4-22)
where
C = concentration of chemical substance at any time, t, during
exposure (mg/m3)
C0 = initial concentration of chemical substance (mg/m3)
m = mixing factor (unitless)
Q = ventilation flow rate (m3/hr)
V = room volume (m3)
t = time during exposure period (hrs).
67
-------
The Initial concentration, .C0, can be estimated for chemical
substances discharged from aerosol containers using the following
equation.
r WF X M X FA
Co = y (4-23)
where
WF = weight fraction of chemical substance In product (unitless)
M = mass of product released (mass)
0V = fraction of product released that 1s overspray (unltless)
V = room volume (m3) .
For products that are spilled, the following equation can be used:
M x H x FA (4-24)
where
FA = fraction of spilled material entrained 1n air (unltless) and the
other variables are as defined previously. Methods for
estimating WF, M, FA, and 0V are presented 1n Section 3 of this
volume.
The equations used to estimate concentrations resulting from
continuous and time-dependent releases are derived from equations for
estimating concentrations resulting from Instantaneous releases. It must
be noted that any type of release requires some amount of time to occur
and, by definition, cannot be truly Instantaneous. For Increased
accuracy, It Is suggested that equations for estimating concentrations
resulting from continuous releases be used for those situations 1n which
a release might be characterized as Instantaneous.
The mixing factor, m, is an empirical number that accounts for
room-specific effects on transport of chemical substances (Repace and
Lowrey 1980). Removal of chemical substances is more rapid in a well-
mixed atmosphere than in a poorly mixed, stable one. Factors that affect
the mixing factor include type and placement of ventilation grills,
ventilation flow rates, inhomogeneous distribution of a chemical substance
in a room, physical barriers, circulation fans, and room traffic (Repace
and Lowrey 1980). A mixing factor of 1.0 implies ideal mixing. If the
environmental conditions are such that the air throughout the room is
continuously and vigorously mixed, then mixing of air in the room is con-
sidered ideal. Table 22 presents values for mixing factors recommended
for several common air supply system configurations. According to Repace
and Lowrey (1980), the best standard condition is the perforated ceiling
68
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Table 22. Values for Mixing Factor Recommended for Several
Common Air Supply System Configurations
Configuration of air supply system Mixing factor
Perforated ceiling* 1/2
Trunk system with amenostats 1/3
Trunk system with diffusers 1/4
Natural draft and ceiling exhaust fans 1/6
Infiltration and natural draft 1/10
* This is the best standard condition.
Source: Repace and Lowrey (1980).
69
-------
air supply system configuration, which has a recommended value of 1/2 for
mixing factor. The air supply system configurations presented In Table 22
are listed in order of most to least thorough mixing of room air.
The ventilation flow rate, Q, 1s the product obtained from multiply-
ing the room volume by the air exchange rate. Table 23 presents values
for typical volumes of rooms in houses and apartments. According to
figures from the Bureau of the Census, the average floor area of new
houses in 1983 was 1780 square feet.* The average ceiling height is
eight feet. The average volume of a new house is, therefore, estimated
to be 14,240 cubic feet, or approximately 403 cubic meters. The main
living space, including living room, dining room, kitchen, one bedroom,
and one bath 1s estimated to be from 110 to 131 m3. The actual values
for room volume are based on professional judgment. Typical air exchange
rates 1n residences are presented in Table 24.
The average concentration following an instantaneous release can be
estimated by Integrating equation (4-22) from the time of Instantaneous
release to any point in time after the Instantaneous release occurs. The
following equation 1s used to estimate the average concentration
following an Instantaneous release.
C;
-C0V\ e -m(Q/V)t + C0V
mQ / rnO
u
tu - tc
where
0 (4-25)
t0 = time at which instantaneous release occurs (hours)
tu = any point in time after the instantaneous release occurs
(hours)
and all other variables 1n equation (4-25) are as defined previously.
It should be noted that equation (4-25) will overestimate average
concentrations resulting from Instantaneous releases of aerosols because
it does not include a factor to account for gravitational settling of
particulates. The derivations of equations (4-22) and (4-25) are
presented in Volume 12 of Methods for Assessing Exposure to Chemical
Substances.
It must be noted that the time at the beginning of exposure and the
time at the end of exposure can be specified at any time after release
begins. The only stipulation is that the time at the beginning of
Stan Rollock, Bureau of the Census, Annual Housing Survey, personal
communication with Peggy Redmond of Versar Inc., April 5, 1985.
70
-------
Table 23. Typical Roam Volumes
Location Volume* (m3)
Typical House
Master bedroom 41
Standard bedrooms (2) 40
Baths (2) 18
Living room 41
Dining room 20
Kitchen 20
Basement (partial) 125
Garage (1 car) 60
Foyer/ha11ways 15
Total 380+
Typical Apartment
Master bedroom 41
2nd bedroom or den 20
Bath 9
Living/dining room 61
Kitchen 20
Foyer/hallways 15
Total 166
*A11 values for room volume are Versar estimates.
+Total volume is less than the value of 403 cubic meters estimated
from Annual Housing Survey data; the difference between these totals
can be attributed to the exclusion of closets in the total volume for
typical house presented in this table.
71
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Table 24. Air Changes Occurring Under Average Conditions in Residences
Exclusive of Air Provided for Ventilationa
Kind of room No. air changes/hour (ACH)
Rooms with no windows or exterior doors 0.5
Rooms with windows or exterior doors on one side 1
Rooms with windows or exterior doors on two sides 1.5
Rooms with windows or exterior doors on three sides 2
Entrance halls 2
aFor rooms with weatherstripped windows or with storm sash, use two-thirds of
these values.
Source: American Society of Heating, Refrigerating, and Air-Conditioning Engineers,
Inc. (1977).
72
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exposure must occur before the time at the end of exposure. The average
concentration during exposure 1s calculated using equation (4-25). The
variable, t^, 1s substituted for t0, and the variable, te, 1s
substituted for tu 1n equation (4-25).
4.4.2 Concentrations Resulting from Continuous Releases of Chemical
Substances
Continuous release scenarios are characterized by a chemical substance
that 1s released at a constant rate until the period of exposure ends or
the source ceases to emit the chemical substance, whichever comes first.
If the exposure continues after the source ceases to emit the chemical
substance, equation (4-22) for calculating room air concentrations during
Instantaneous releases 1s used. The value for C0 used 1n equation
(4-22) would be the value of C at the time at which the solvent ceased
to be emitted. Examples of scenarios 1n which the rate of release 1s
continuous include (1) single releases of chemical substances from
pressurized aerosol products for time periods of more than a few seconds;
(2) multiple discharges of chemical substances from pressurized aerosol
products 1n which each discharge occurs within a short time of the other;
(3) releases of chemical substances from films formed- when products are
spilled or sprayed Instantaneously onto surfaces; and (4) releases of
migrants from solid matrices or bulk liquids. Equation (4-26) is used to
calculate the concentration in the room at any time, t, prior to cessation
of release of the chemical substance. The initial concentration is
assumed to be zero.
_G _G e-m(Q/V)t (
C ~ mQ mQ (
If the initial concentration is not equal to zero,
where
c . .1, C0 _ _G e-n
mQ mQ
G = release rate of the chemical substance calculated using the
appropriate method (see Section 4.3) (mg/hr)
m = mixing factor (unitless)
Q = ventilation flow rate (m3/hr)
V = room volume (m3) .
Equation (4-28), the integrated form of equation (4-26), is used to
calculate the average concentration in the room during release of the
chemical substance.
.73
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Cave =
G
mQ
GV \ e-m(Q/V)t
tg - t0
(4-29)
where
tg = time at which release of the chemical substance ceases (hours),
and the other variables of equation (4-28) are as defined previously. The
room air concentration at the time at which the chemical substance Is no ,
longer released, C^g, 1s calculated by substituting tg Into equation
(4-26). For continuous releases, the parameter, tg, is calculated using
the following equation:
tg =
(4-29)
where
H
G
= mass of chemical substance released from aerosol product, or
mass applied, sprayed, or spilled onto a surface
= release rate of the chemical substance calculated using the
appropriate method (see Section 4-3) (mass/hour).
Equation (4-30), a variation of equation (4-22), Is used to calculate
the room air concentration at any time, t, after release of chemical
substance from the source has ceased.
C = ctge-m(Q/V)(t-tg)
(4-30)
Equation (4-31) Is used to calculate the average concentration from the
time the release of chemical substance has ceased until any point In time
greater than the time at which release of the chemical ceases.
*
tg
e-m(Q/V) (t-tg
v,
(4-31)
where
tu = any point 1n time greater than the time at which release of
the chemical ceases (hours).
If average concentrations are desired for a period starting before
release ceases and ending after release of the chemical substance from
the source has ceased, the average concentration during this period can
74
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ave (after release)
be estimated by calculating a time-weighted average of the average
concentration during release and the average concentration after release
has ceased:
Cave (during period that starts before release ceases, but ends
after release ceases) =
C x
ave (during release)
The derivations of equations (4-26) through (4-31) are presented In
Volume 12 of Methods for Assessing Exposure to Chemical Substances.
In estimating average concentrations during exposure, It must be
noted that the time at the beginning of exposure and the time at the end
of exposure can be specified at any time after release begins. The only
stipulation 1s that the time at the beginning of exposure must occur
before the time at the end of exposure. Three possible cases for the
time at the beginning of exposure and the time at the end of exposure are
the following:
Case 1: The time at the beginning of exposure and the time at the
end of exposure are less than the time at the end of
release. In this case, the average concentration during
exposure 1s calculated using equation (4-28). The
variable, t^, 1s substituted for t0 and the variable,
te, Is substituted for tg In Equation (4-28).
Case 2: The time at the beginning of exposure Is less than the
time at the end of release and the time at the end of
exposure 1s greater than the time at the end of release.
In this case, the average concentration during exposure 1s
calculated using equations (4-28), (4-31), and (4-32).
The variable, t^, Is substituted for t0 In equation
(4-28). The variable, te, Is substituted for tu In
equation (4-31). The average concentration during release
obtained from equation (4-28) and the average
concentration after release obtained from equation (4-31)
are used In equation (4-32) to obtain the average
concentration during exposure. In addition, t^ Is
substituted for t0 and te Is substituted for tu In
equation (4-32).
Case 3: The time at the beginning of exposure and the time at the
end of exposure are greater than the time at the end of
release. In this case, the average concentration during
exposure Is calculated using equation (4-31). The
variable, tj-,, Is substituted for tg, and the variable,
te, Is substituted for tu In equation (4-31).
75
(4-32)
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4.4.3 Concentrations Resulting from Time-Dependent Releases of
Chemical Substances
The following equations are applicable for estimating concentrations
that occur when the rate of release of a chemical substance Is time-
dependent. These equations are applicable to scenarios In which a
coating or film containing the chemical substance for which exposure Is
being assessed 1s applied to a surface and the time required for
application 1s more than a few minutes. To use this method, the assessor
must first ascertain whether the time for evaporation of the chemical
substance from the film, once It 1s applied to the surface (tg), 1s
less than, greater than, or equal to the time required to apply the film
to the surface (ta). A method for estimating the time required to
apply a film to a surface 1s presented 1n Section 3.1 of this volume.
The following expression 1s used to estimate tg for a time-dependent
release.
tg = M/ta/GNAR (4-33)
where M 1s the total mass of chemical substance 1n the film applied
to the surface and G^AR 1s calculated using the method cited 1n
Section 4.3.
This method for estimating tg assumes that evaporation occurs at a
constant rate. Because of the effect that drying of the coating or film
may have on the release rate and because some chemical substances do not
evaporate completely from the film or coating before the coating dries
(Newman et al. 1975; Newman and Nunn 1975), the assumption of constant
release until the entire mass of chemical substance 1s released may not
be true. It 1s recommended that the value of tg obtained using
equation (4-33) be used only to estimate concentrations during release up
to the time reported for the specific coating to form a dry film, If this
time is known.
Four equations are used to calculate concentrations in indoor air
resulting from time-dependent releases of chemical substances. These
equations mathematically describe four physical situations that occur at
specific intervals that characterize a time-dependent release. For the
case 1n which the time for evaporation of the chemical substance from the
film once 1t 1s applied to the surface 1s less than the time to apply the
film to the surface (Case 1), a description of the physical situation
during each of the four Intervals follows:
(1) t0 < t < tg: Mass of chemical substance released is increasing
and concentration at any time, t, is increasing during
this interval. The mass of chemical substance released
1s increasing because of the additional mass being
applied to the surface.
76
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(2) tg < t < ta: The mass of chemical substance released remains
constant and the concentration 1s Increasing. The
additional mass applied to the surface 1s balanced
equally by the portion of the surface from which the
chemical has already evaporated.
(3) ta < t < tr: The variable tr denotes the time at which the very
last bit of chemical substance has been released from
the surface. During this Interval, the film is no
longer being applied but chemical substance is still
being released. Therefore, the mass of chemical
substance released 1s decreasing. Whether the
concentration at any time, t, during this interval is
Increasing or 1s decreasing is determined by the air
exchange rate.
(4) tr < t < tu: The mass released 1s zero. The concentration is
decreasing with time as ventilation air flows out
of the room.
For the case 1n which the time for evaporation of the chemical
substance from the film once it 1s applied to the surface is greater
than, or equal to the time to apply the film to the surface (Case 2), a
description of the physical situation during each of the four intervals
follows:
(1) t0 < t < ta: Mass of chemical substance released 1s increasing,
and concentration at any time, t, is Increasing during
this Interval. The mass of chemical substance released
1s increasing because of the additional mass being
applied to the surface.
(2) ta < t < tg: Mass of chemical substance released remains constant,
and the concentration at anytime, t, continues to
increase during this interval.
(3) tg < t < tr: The mass of chemical substance released is
decreasing.
(4) tr < t < tu: The mass of chemical substance released is zero,
and the concentration is decreasing with time.
By making appropriate substitutions, one set of equations can be used
to determine concentrations for both of the cases described previously.
For Case 1, let tg equal t-| and ta equal ^2- For Case 2» 1et
ta equal t], and tg equal t2- The following equations are used
to determine the concentration of chemical substance at any time, t,
during each interval and the average concentration during each interval.
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The average concentration during the exposure period is determined by
calculating a time-weighted average based on the average concentration
calculated during each interval. Note that k = mQ/v.
(1) From t0 to t-\:
VR[; i
Vk Ik
(4-34)
VR
Vk
ft2-
.2
t -
k
e-kt
k2
ave
- *
(4-35)
(2) From t-j < t <
C =
VR
Vk
t, _
-e
-kt
(4-36)
VR
Vk
ave
(4-37)
(3) From t2 < t < tr
C = -
VR
Vk
VR
"vT\ k
t t
r '
(4-38)
ave
e-k(t-V
k
"GNA/I + t _ t \ c
Vk \k r '/ t2
*
t (
Vk u\ k
*v Ml
r 2 ;J
tr
t2
t, - t, (4-39)
where
C. = concentration at the time, tj, calculated using
2 equation (4-36).
78
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(4) From tr < t < tu
where
C.
(4-40)
\
-e
-k(t-t
r>
k2
t
u
*r
*r
(4-41)
concentration at the time at which release ends calculated
using equation (4-38) (mass/volume).
It must be noted that the time at the beginning of exposure and the
time at the end of exposure can be specified at any time after release
begins. The only requirement 1s that the time at the beginning of
exposure must occur before the time at the end of exposure. To delineate
the possible cases that can occur, the convention that t-| corresponds
to ta or tg, whichever Is smaller, and that t2 corresponds to ta
or tg, whichever 1s larger, Is used. Possible cases for the time at
the Beginning of exposure and the time at the end of exposure 1n relation
to t-j , t2, tr, and tu Include the following:
Case 1 : The time at the beginning of exposure and the time at the
end of exposure are less than or equal to t-| . In this
case, the average concentration during exposure is
calculated using equation (4-35). The variable, t^, is
substituted for t0 and the variable, te, is
substituted for t-| , in equation (4-35).
Case 2: The time at the beginning of exposure is less than or
equal to t] , and the time at the end of exposure Is
greater than t-\ , but less than or equal to t2- In
this case, the average concentration during exposure is
the weighted average of average concentrations calculated
using equations (4-35) and 4-37). The variable, t^,, is
substituted for t0 in equation (4-35). The variable,
te, is substituted for t2 in equation (4-37).
Case 3: The time at the beginning of exposure is less than or
equal to t-j , and the time at the end of exposure is
greater than t2, but less than or equal to tr. In
this case, the average concentration during exposure is
the weighted average of average concentrations calculated
79
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using equations (4-35), (4-37), and (4-39). The variable,
tb, is substituted for t0 in equation (4-35). The
variable, te, is substituted for tr in equation (4-39).
Case 4: The time at the beginning of exposure is less than or
equal to t-|, and the time at the end of exposure is
greater than tr. In this case, the average
concentration during exposure is the weighted average of
average concentrations calculated using equations (4-35),
(4_37), (4-39), and (4-41). The variable, tb, is
substituted for t0 in equation (4-35). The variable,
te, is substituted for tu in equation (4-41).
Case 5: The time at the beginning of exposure and the time at the
end of exposure are greater than t-| but less than or
equal to t£. In this case, the average concentration
during exposure is calculated using equation (4-37). The
variable, tb, is substituted for t-|, and the variable,
te, is substituted for t2 in equation (4-37).
Case 6: The time at the beginning of exposure is greater than
t-|, but less than or equal to t2- The time at the end
of exposure is greater than t2, but less than or equal
to tr. In this case, the average concentration during
exposure is the weighted average of average concentrations
calculated using equations (4-37) and (4-39). The
variable, tb, is substituted for t] in equation
(4-37). The variable, te, is substituted for tr in
equation (4-39).
Case 7: The time at the beginning of exposure is greater than
t-|, but less than or equal to t2- The time at the end
of exposure is greater than tr. In this case, the
average concentration during exposure is the weighted
average of average concentrations calculated using
equations (4-37), (4-39), and (4-41). The variable, tb,
is substituted for t-\ in equation (4-37). The variable,
te, is substituted for tu in equation (4-41).
Case 8: The time at the beginning of exposure and the time at the
end of exposure are greater than t2, but less than or
equal to tr. In this case, the average concentration
during exposure is calculated using equation (4-39). The
variable, tb, is substituted for t2, and the variable,
te, is substituted for tr in equation (4-39). The
concentration at the time at the beginning of exposure,
Ctb, is substituted for Ct2 in equation (4-39). Ctb
is calculated by substituting tb for t in
equation (4-36).
80
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Case 9; The time at the beginning of exposure Is greater than
t2, but less than or equal to tr. The time at the end
of exposure 1s greater than tr. In this case, the
average concentration during exposure Is the weighted
average of average concentrations calculated using
equations (4-39) and (4-41). The variable, tb, 1s
substituted for t2 1n equation (4-39). The variable
te, 1s substituted for tu 1n equation (4-41). The
concentration at the time at the beginning of exposure,
(^5, 1s substituted for Ct2 1n equation (4-39). Ctb
1s calculated by substituting tD for t 1n equation
(4-36).
Case 10: The time at the beginning of exposure and the time at the
end of exposure are greater than tr. In this case, the
average concentration during exposure Is calculated using
equation (4-41). The variable, tb, Is substituted for
tr and the variable, te, 1s substituted for tu 1n
equation (4-41). The concentration at the time at the
beginning of exposure, Ctb, Is substituted for Ctr 1n
equation (4-41). Ctr 1s calculated by substituting tb
for t 1n equation (4-38).
It must be noted that the physical situations described for the
Intervals comprising these two cases are generally applicable under
environmental conditions considered most likely to occur Indoors. If,
however, the ventilation air flow rate Is sufficiently high to offset the
rate at which the chemical substance 1s released, the physical situations
that occur during each Interval will vary from those previously
described. Additional data are required to determine the combination of
release rate of chemical substance and air exchange rate that would cause
the actual physical situation to deviate. The derivations of equations
(4-34) through (4-41) are presented 1n detail 1n Appendix E of this
volume.
Under some circumstances, the concentrations predicted using these
methods may exceed the saturation concentration of the chemical substance
under the environmental conditions for which It 1s being modeled. Such
circumstances are most likely to be encountered In scenarios in which a
large mass of a chemical substance with a relatively low vapor pressure
is available for release from surfaces to which a film containing the
chemical substance Is applied.
A reason for predicted concentrations' exceeding the saturation
concentration is the underlying assumption of the methods presented in
this section that release occurs at a constant rate. Release at a
constant rate can only be assumed if the kinetics of mass transfer are
slow enough that the concentration of the chemical substance in the room
81
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never reaches a level that 1s high enough to have an appreciable effect
on the rate of release. If the kinetics of mass transfer are fast enough
that equilibrium 1s approached before the film or coating dries, the rate
of release will decrease exponentially; a numerical method of solution
must Instead be used to provide estimates of concentrations occurring
during exposure. To Implement a numerical method of solution, a computer
program must be used because of the extensive calculations that must be
carried out.
In the event that the average concentration predicted using the
equations described previously exceeds the saturation concentration of
the chemical substance 1n any of the four Intervals during exposure, 1t
Is suggested that the assessor substitute the saturation concentration
for the value of the average concentration during that Interval. The
average concentration during the exposure period Is then determined by
calculating a time-weighted average from the average concentration used
during each applicable Interval.
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-( i .iX--1* >--«-':i '
*
5.
EXPOSED POPULATIONS
Studies of populations exposed to chemical substances in consumer
products comprise three basic elements:
Identification of exposed populations
Enumeration of exposed populations
Characterization of the population according to age and/or sex.
Identification of the exposed populations relies on identification of
consumer products containing the chemical substance of concern. The
users of the products (i.e., those who actively use and those who are
present during use) are the exposed population. Once the users are
identified, the exposed population can be enumerated and characterized by
the methods described in Volume 4 of this series, Methods for Enumerating
and Characterizing Populations Exposed to Chemical Substances. EPA
560/5-85-004 (Dixon et al. 1985). This section will summarize the
population enumeration report and indicate how it applies to consumer
exposure assessment.
5.1
Identification of Exposed Populations
The steps required for identifying the population exposed to a
chemical substance in consumer products can be summarized as follows:
1. Use the data sources discussed in Section 3, or for a new
chemical substance consult the Premanufacture Notice (PMN), to
compile a list of the consumer products known to or thought to
contain the chemical substance of interest.
2. Determine whether all or a portion of the consumer product class
contains the chemical substances; if possible, identify the
product by brand name to expedite enumeration.
3. Identify products obviously intended for use by males or females
or specific age groups.
4. Evaluate each product to determine whether passive exposure is of
concern. Consumer product use patterns and chemical release
patterns will identify the passively exposed population (i.e.,
family or household members).
5.2 Enumeration of the Exposed Population
Enumeration of the population exposed to a chemical substance in
consumer products depends on two factors: (1) the availability of use
data specific to the products and (2) whether both active and passive
exposure to the chemical substance is involved. The following subsections
83
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briefly review the sources of available data and the methods for their
use. Volume 4 of the series, Methods for Assessing Exposure to Chemical
Substances presents methods for enumerating populations exposed to
chemical substances.
5.2.1 Enumeration of Exposed Populations via Simmons Market Research
Bureau Reports
The Simmons Market Research Bureau (SMRB) reports are described In
detail 1n Volume 4 of this series; they are also discussed 1n Section 6.2
and Appendix D of this volume. Briefly, SMRB Is a market research
corporation that collects Information on the buying habits of the U.S.
population. SMRB collects this Information for over 1,000 consumer
products. For each consumer product, SMRB also collects data on the
specific product type (e.g., aerosol rug shampoo versus liquid rug
shampoo) as well as the brand name (e.g., Bissell Shampoo versus
Johnson's Shampoo). For each type and brand name product, SMRB collects
Information on the frequency of use (described in greater detail 1n
Section 6.2 of this report), the total number of buyers as well as the
number of buyers in each use category, and the demographics (e.g., age,
race, employment, economic level, geographic location) for the buying
population. All this Information 1s presented 1n a series of 29 volumes
organized according to major product categories. The 29 volumes of SMRB
data collected in 1982 have been purchased by EPA-OTS and are Included in
the Exposure Evaluation Division library.
Enumeration of populations exposed to a chemical substance in a
consumer product 1s, therefore, a straightforward process with the use of
the SMRB reports. It should be noted, however, that SMRB presents the
consumer product data according to the "buyer" and not necessarily
according to the user (i.e., actively exposed individuals). It may be
necessary to adjust the data to reflect potential uses in a household.
The Investigator must judge on a case-by-case basis how to use the data
to accurately represent the user or actively exposed population. Popula-
tions that are passively exposed as a result of their proximity to the
product both during and following Its active use may also be estimated
via SMRB data. For product buyers, SMRB reveals the frequency
distribution of household size. For example, SMRB may present 1,000
female homemakers (I.e., the actively exposed popula- tlon) as purchasers
of rug shampoo. For the 1,000 female homemakers, SMRB depicts the number
of households having 1, 2, 3 or 4, or 5 or more persons; these households
would also total 1,000. To approximate the number of persons living in
the 1,000 households and potentially passively exposed to the chemical
substance in rug shampoo, the Investigator can apply the frequency
distribution and household size. Ranges can be used to accurately
estimate the exposed population; use of the high end of the ranges
generates a conservative estimate of exposed persons.
84
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The SMRB data are clearly Intended to describe the market variability
of existing products. Consequently, the data are generally more
applicable to existing chemicals and product formulations currently on
the market than to new chemical substances. The SMRB data may, however,
prove useful to assessments of PMN substances when the new chemical Is
Intended for use as a substitute for an existing chemical. If use
Information Included 1n a PMN submlttal 1s sufficiently detailed, the
SMRB data can be used to predict the number of exposed consumers.
Finally, as part of the Investigation and development of this methods
report, considerable population data have already been extracted and
recorded for many of the consumer products under Investigation (as listed
1n Section 1.3).
5.2.2 Enumeration of Exposed Populations via Production and Sales Data
For consumer products not covered by SMRB, the users can be enumerated
by applying a number of assumptions and estimation techniques to economic
data such as chemical production volume, Census of Manufacturers output,
and retail sales Information. To enumerate the users of a consumer
product, the investigator must estimate the number of units of a product
bought by consumers, and then apply such data on use patterns to
determine the average number of consumers. This method can be summarized
in the following steps.
1. Determine the number of units of the product sold or produced
annually according to one of the following options:
- Consult the Census of Manufacturers (Bureau of the Census 1980b)
to obtain production in unit quantities.
- Estimate the number of units produced by dividing the amoun't of
the chemical destined for that use by the formulation percent
and the total mass of product per unit. (Note: This
Information must be derived from the materials balance for the
chemical substance of concern.)
2. Determine the use patterns for the product. SMRB reports provide
data on frequency of use of consumer products. Based on product
similarities, the investigator can estimate use patterns (e.g.,
number of units used per year).
3. Calculate the exposed population by dividing the production volume
units by the units used per person per year.
The results of this approach will be an estimate, but a fairly valid one;
the parameters used in the calculation are from reliable sources.
85
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5.2.3 Enumeration of Exposed Populations via Chemical-Specific
Information
Various sources of chemical-specific Information can also be used to
enumerate exposed populations In lieu of SMRB or production and sales
data. The Information sources Include the following:
Consumer product associations as listed 1n the Encyclopedia of
Associations.
Government agencies (e.g., Food and Drug Administration (FDA),
Consumer Product Safety Commission (CPSC), Bureau of the Census
(see Section 3.4 for additional Information).
Publications of the Bureau of the Census (e.g., Annual Housing
Survey. The Statistical Abstract of the United States).
The published literature can also provide valuable information on the
users of consumer products.
5.3 Characterization of Exposed Populations
Consumer inhalation and ingestion rates and surface areas for
potential dermal contact are a function of the Individual's age and sex.
Accurate estimates of exposure distributions, therefore, require
characterization of the exposed population according to age and sex. If
the chemical substance of concern has special effects on particular age
classes such as the elderly or children, further characterization of the
population 1s required. Another example would be a chemical substance
that has been determined to be teratogenic; enumeration of women of
child-bearing age may then be required.
Data sources for characterizing the exposed population include the
SMRB reports and the general age and sex distribution of the U.S.
population. Procedures for characterizing exposed populations can be
summarized as follows:
1. If the consumer population was enumerated by the use of SMRB
data, use the demographic characteristics reported for buyers/
users to characterize the actively exposed population by age and
sex. Populations enumerated by other methods can also be
characterized by consulting the SMRB reports for the product(s)
most similar to that being assessed.
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2. Consult Volume 4 (Table 12) of the exposure assessment methods
series to derive generic age and sex distribution for:
- Consumer populations under the age of 18
- Passively exposed household members
- The entire U.S. population.
87
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88
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O Jsi*
\ i
6. EXPOSURE ANALYSIS
Before discussing exposure, 1t 1s necessary to differentiate between
the concepts of "exposure" and "dose." Dose 1s the amount absorbed by
the receptor; exposure refers to the quantity contacting the receptor and
available for absorption. To be absorbed, a substance must pass a
barrier: the gastrointestinal (or oral) epithelium in the case of
ingestion exposure, the pulmonary epithelium for respired substances, or
the epidermis 1n the case of dermal contact. Whether the results of an
assessment are to be expressed as exposure or as absorbed dose depends on
what use is to be made of the exposure assessment (see Volume 1 of this
series). If results in terms of absorbed dose are desired, units are
often expressed as mass of chemical / kilogram of body weight / day. A
table of average body weights, in kilograms, for humans is presented in
Appendix D. Average body weight values in this table are presented by
age group. In actual practice, experimental data measuring absorption of
chemical substances is limited to a few specific chemical substances and
conditions. Although methods for estimating absorption will be
discussed, the emphasis 1n this volume will be on exposure.
Section 6 is divided into three subsections. Section 6.1 defines
exposure pathways and explains their relevance to exposure analysis.
Section 6.2 discusses methods for calculating exposure. Current
knowledge of absorption parameters is summarized 1n Section 6.3.
Emphasis is on pathways and scenarios of interest to OTS and on sources
of chronic low-level (rather than acute) exposure. A detailed discussion
of key factors governing deposition of particles in regions of the
respiratory tract and of methods for estimating Inhalation exposure to
aerosols is presented 1n Appendix A.
6.1 Exposure Pathways and Routes
An exposure route is the means by which a pollutant in a given medium
contacts or enters the receptor. A pathway is the history of the flow of
a pollutant from the source to receptor, including qualitative
description of emission type, transport, medium, and route. This section
will discuss significant pathways of exposure from consumer products.
All of these pathways are not covered in this volume. They are all
listed here so they can be put in perspective.
6.1.1 Inhalation Pathways
Although Inhalation exposure is probably more significant in the
ambient and occupational settings, it may reach levels of grams per year
1n the consumer setting. Consideration of odor thresholds suggests that
Inhalation exposures from volatile household chemicals may reach levels
of grams per person (Becker et al. 1979). Reports of acute inhalation
toxicity from consumer products are largely restricted to cases of carbon
89
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monoxide poisoning. Reports of subacute toxidty are fairly common,
e.g., pneumonltls from household pyrethrum use (Carlson and Villaveces
1977), eplstaxls and liver-function abnormalities associated with
consumer use of butyl caulk (NIOSH 1982b), and systemic toxidty from
mothballs (Stricof et al. 1983). There is also increasing awareness of
the fact that household solvents and pesticides may be associated with
various subcllnical, delayed, or otherwise overlooked chronic effects
such as altered mental states and behavioral manifestations (Levin et al.
1976, Clark 1971). Finally there is a small, but significant,
subpopulation of hypersensitive persons who display symptoms at substance
concentrations harmless to most people (Sandifer et al. 1972).
Inhalation pathways are the most complex to analyze and quantify,
since they always involve transport through a medium (air) and associated
emission, fate, and other parameters, which are only occasionally
involved in dermal and ingestlon pathways.
The physical state of the inhaled substance may be gaseous or aerosol
(I.e., a suspension of liquid or solid particles 1n air). Significant
pathways can be summarized as follows:
Inhalation of an aerosol resulting from the spray application of a
product. The spray may be directed onto the user's person, onto a
surface to be treated, or into the air itself (as in a room
deodorant or pesticide space spray). Exposure may also result
from the aerosolizatlon of a poured liquid.
Inhalation of gas evaporating from a liquid surface. This surface
may be a film on an object to which the liquid has been sprayed or
otherwise applied; the liquid may also be evaporating from a
container left open during use of the product.
Inhalation of a gas diffusing from a solid matrix, e.g., from
plastics, dry paint films.
Inhalation of solid particles resulting from (a) application or
pouring of dusts or powders; (b) use or modification of a solid
product, e.g., by sawing; or (c) re-entrainment during sweeping,
dusting, etc.
Inhalation of gas or particles resulting from the indoor or
outdoor combustion of fuels or other products, e.g., candles,
matches, or firelogs.
Methods for all of the above, except the last item and (b) and (c) of the
fourth item, are delineated in this methods report.
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6.1.2 Dermal Pathways
Acute poisoning via dermal exposure 1s Infrequent In the consumer
setting, although cases have been reported, e.g., fatalities from aniline
1n canvas shoes and laundry markers (Becker et al. 1979). Local
Irritation and sens1t1zat1on are more commonly reported, e.g., contact
dermatitis from chemicals 1n paper (Marks 1981) and 1n home dyes (NIOSH
1982a).
The most common pathways Involve direct contact with a liquid or
powdered product. These may be applied to the body directly or contacted
during use or application; the product may also be contacted accidentally
when one touches the surface to which 1t has been applied.
Additional dermal exposure pathways Include the following:
Exposure to aerosol droplets or dust particles suspended 1n the
air. The relevant variables are difficult to quantify and Include
such parameters as motion of the receptor through the room.
Dermal exposure to gases.
Exposure to solid products,
No scenarios have been developed for the first two pathways listed
above. Contact with solids can be further broken down as follows:
Exposure to Ingredients leached, diffused, or dissolved out of a
solid matrix; e.g., plastldzers In plastic products or pesticides
1n pressure-treated wood. Such exposure 1s of particular concern
when the receptor 1s hypersensitive to the substance; In such a
case, the slightest contact with the solid object Itself may cause
a toxic reaction, even though the absorbed dose may be below the
limits of accurate quantification. No scenario has been developed
for this pathway.
Exposure to chemical substances In clothing. These substances may
be Ingredients of the fabric (e.g., dyes) or contaminants (e.g.,
detergent residues). This pathway 1s separated from the above
because opportunities for exposure to a chemical used on fabric
are much higher. Fabric used to make clothing Is 1n contact with
the skin for many hours per day. Systemic toxldty has been
reported 1n a series of cases Involving Inadvertent contamination
of a shipment of clothing as the result of a pesticide spill
(Roueche 1971).
Exposure to fragments or fibers which have become embedded in the
skin (e.g., steel wool, glass wool, insulation). Such exposure is
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beyond the scope of this volume, since resulting symptoms are more
likely due to physical irritation than to chemical toxicity per se
(although subsequent chemical absorption via leaching or
dissolution is possible). In any case, this is not a true dermal
pathway but a subcutaneous injection pathway (see Section 6.1.4).
Exposure from rub-off of surface material which subsequently
adheres to the skin as a powder (e.g., dried ink on printed
matter; dust from cat box filler, charcoal briquets, or
insulation).
Contact with dust generated or released during installation,
machining, or removal/demolition of a solid product (e.g.,
wallboard, roofing, tile, lumber).
The last two pathways mentioned are considered identical to dust
exposure, and methods are delineated accordingly.
6.1.3 Ingestion Pathways
Ingestion is the most significant route of exposure to toxic
substances when incidents of acute toxicity are considered. Data
compiled by the National Center for Health Statistics (NCHS) suggest that
at least 1,200 people yearly receive oral doses of between 5 and 30 grams
of single chemicals in paints, cleaning agents, disinfectants, and
petroleum products, based on the number of fatalities reported and the
toxicities of the relevant ingredients (Becker et al. 1979). There are
insufficient data to present typical ranges for cumulative annual
ingestion of individual chemicals resulting from chronic, rather than
acute, exposure to consumer products. Exposure resulting from ingestion
of contaminated food and drinking water will not be considered in this
volume. Exposure via food is covered by Volume 8, and exposure via
drinking water is covered in Volume 5 of the exposure assessment methods
series.
The following pathways may result in significant exposure:
Deliberate ingestion of a product not meant to be ingested (see
below).
Accidental transfer to the mouth of a chemical that has
contaminated or settled on the hands or face during use. There is
currently no reliable method for assessing such exposure.
Contamination of food in the home, e.g., during preparation,
storage, or serving. In this case, the subject chemical is an
extraneous household pollutant rather than a food ingredient or
additive; examples include detergent residues, plasticizers in
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film wrap, and Teachable/soluble constituents of vessels, dishes,
or silverware. This pathway can be significant for chronic
exposure. Occasional cases of acute toxicity occurring by this
pathway have been reported, e.g., from lead in pottery and in
cocktail glasses (Bird et al. 1982). Exposure may also occur via
settling onto food of airborne particles or aerosol droplets.
Such infrequent events lack predictable common characteristics and
do not lend themselves to analysis via standardized scenarios.
Ordinary use of objects designed to be used in the mouth. This
category is basically restricted to infants' toys such as teethers
and pacifiers and to such unusual items as athletic mouthguards.
It may also apply to dental fillings and prostheses. In this
pathway, the subject chemical must be leached or dissolved out of
the solid matrix.
Liquids normally used in the mouth but not intended to be
swallowed. Examples include toothpaste and mouthwash; some of
this may be swallowed, and some absorbed by the oral mucosa.
Ingestion as a subset of inhalation, i.e., swallowing of inhaled
particles too large to be respired.
Methods are delineated in this volume for the last three pathways.
Methods for estimating exposure from deliberate Ingestion of products
will not be delineated in this volume, despite the frequency and
seriousness of clinical poisoning via this pathway, for several reasons.
Deliberate ingestion of inedible substances may be either purposeful
(e.g., pica, suicide) or not (e.g., product mistaken for something
edible). Exposure may involve the ingestion of a chemical substance per
se, usually in liquid form, or the swallowing of a solid object, e.g., a
pill bottle desiccant (Muhletaler et al. 1980). The swallowing of
objects is essentially a product safety consideration and is beyond the
scope of OTS responsibility. (However, it should be noted that the body
may absorb toxic substances released from the ingested object during
gastrointestinal retention (Litovitz 1983).) Deliberate Ingestion of
liquids will not be considered. Quantifying acute threats requires a
different approach from that used to predict isolated incidents of
negligence or misuse.
It should be noted that some unusual forms of exposure may fall into
more than one setting. An example is a reported case of drinking water
contamination from phenol originating from the tank liner of a solar
water heater (Trincher and Rissing 1983). Volume 5 of this series
describes the framework for calculating exposure to chemicals
contaminating drinking water, and presents data on such required input
parameters as daily drinking water intake. However, the water heater in
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question is purchased and operated by consumers; therefore, other
parameters (e.g., exposed population, chemical release, and ultimate
concentration) must be calculated by methods discussed 1n this volume.
Such "hybrid" exposures are relatively uncommon and should be handled on
a case-by-case basis.
6.1.4 Other Pathways
Chemicals may be absorbed from consumer products via routes other
than the three most common ones discussed above. No scenarios will be
developed for these; however, they will be listed for completeness.
Three examples that may occasionally be significant Include: (1) direct
ocular absorption, e.g., of pesticide vapors (Morgan and Roan 1974);
(2) use of rectal and vaginal suppositories or devices; and (3) Injection
(subcutaneous or other).
The last two categories are restricted to use of medical products, at
least under ordinary circumstances, and are therefore beyond the
jurisdiction of EPA. Exceptions Include penetration of the skin by
fibers (e.g., asbestos) and trauma (e.g., the accidental Injection Into
the hand via spray-gun of lead-containing paint) (LHIs et al. 1981).
Such Incidents are unpredictable and not amenable to" quantification.
Medical Implants and prostheses are also excluded from
consideration. Note that contact with oral mucosa Is Included under
"Ingestlon" and with the upper respiratory epithelium under "Inhalation."
6.2 Exposure Calculation
This section presents methods and data needed to estimate exposure.
Frequency of use 1s a parameter required to estimate annual exposure to
consumer products for Inhalation, dermal, and Ingestion pathways.
Section 6.2.1 provides Information to aid the assessor in determining
frequency of use. Methods for estimating inhalation exposure are found
1n Section 6.2.2. Section 6.2.3 presents methods for estimating dermal
exposure, while Section 6.2.4 cites methods for estimating ingestion
exposure. Methods for estimating Inhalation exposure to particulates
discharged from consumer products are presented in Appendix A.
6.2.1 Frequency of Use
Market research reports are a very useful source of data on product
use frequency. One readily available series of market research reports
is the Simmons Market Research Bureau (SMRB) reports. SMRB is a market
research corporation that collects information on the buying habits of
the population through questionnaires administered to a nationwide panel
of consumers. This study, The Simmons Media and Market Report (SMRB
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1982), 1s designed to serve retailers, advertising agencies, and the
media by providing up-to-date, comprehensive Information on current and
potential sales markets for consumer products.
Appendix B lists products covered In SMRB by volume. For each
product category, section IB of SMRB usually Indicates how many
households buy or use the product. If the product requires Installation,
SMRB often Indicates the number of persons Installing It themselves.
Products are often broken down by type, e.g., aerosol, liquid, powder.
Populations are reported for heavy, medium, and light use categories
(H, M, L). These are defined separately for each product, and a table Is
provided. This permits calculation of a distribution of frequency of use.
In many Instances, SMRB reports the number of containers, cans, or
bottles purchased per time period Instead of the number of uses. To
translate these data Into uses per year, 1t 1s necessary to know how much
product 1s consumed per use, and how much 1s contained In a single
container. This Information can be obtained from a number of sources,
Including product labels, or contact with trade associations, Industry,
users' (e.g., hobby) associations, and government agencies such as CPSC
or FDA. These same sources can also be consulted when a particular
product 1s not listed 1n SMRB.
6.2.2 Inhalation Exposure
Inhalation exposure 1s defined for the purpose of this report as the
quantity of a chemical substance that 1s taken Into the body via the
Inhalation route during a given period of time. Exposure Is to be
distinguished from absorbed dose, which refers to the quantity of
chemical absorbed across biological membranes as a result of exposure.
Background Information on the Inhalation route of exposure Is provided
In (1), followed by a discussion of the method used to estimate
Inhalation exposure to gases and vapors In (2).
(1) Background. Chemical substances present In ambient air as
gases or vapors may be Inhaled, thus contributing to exposure via the
lungs. Although a significant fraction of the Inhaled chemical may be
exhaled, this fraction 1s chemical-specific and thus not easily
predicted. For this reason, exposure estimates for gases and vapors are
based on the entire quantity of Inhaled chemical. Aerosols (I.e.,
suspensions of small liquid or solid particles In air), however, are
subject to differential deposition 1n various regions of the respiratory
tract. Particle deposition patterns can be roughly predicted based on
knowledge of the particle size distribution of Inhaled aerosols.
Particle sizes are usually measured as particle aerodynamic diameter,
defined as the diameter (In \im) of a sphere of unit density having the
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same terminal velocity as the particle 1n question, regardless of Its
shape and density (Marple and Rubow 1980). Exposure calculations for
Inhaled aerosols can be refined by Incorporating Information on particle
size distribution and knowledge of the relationship between particle size
and respiratory tract deposition patterns. A detailed discussion of key
factors governing deposition of particles and of methods for estimating
Inhalation exposure as a function of regional deposition of particles In
the respiratory tract 1s presented 1n Appendix A of this volume.
(2) Exposure Calculation. Assessment of Inhalation exposure to
consumer products Involves finding a simple or complex solution to the
following equation:
= i
C(t)dt
(6-1)
where
t
C(t)
= Inhalation exposure (mass/time)
= Inhalation rate (volume/time)
= duration of exposure (time)
= concentration of chemical In air as a function of time
(mass/volume).
In practice, the algorithm used to calculate Inhalation exposure Is
usually an Integrated and simplified version of equation (6-1), often
Incorporating simplifying assumptions about the change 1n concentration
with time. (See Section 4 for a detailed discussion of methods for
calculating concentration.) In many cases, exposures can be calculated
using an average concentration for a given period of time; exposures from
several such consecutive time periods can be summed to estimate total
Inhalation exposure to a given product. The simplified version of
equation (6-1) 1s presented below.
IHX = IR x DU x FQ x CN
(6-2)
where
IHX = Inhalation exposure (mg/yr)
IR = Inhalation rate (m3/hr)
DU = duration of exposure event (hours)
FQ = frequency of exposure (events per year)
= average Indoor air concentration of a given constituent
(mg/m3).
CN
The variables of equation (6-2) are determined as follows:
m3/h
r.
(a) Inhalation rate. Inhalation rate (IR) Is expressed In
The factors that have the most Influence on human lung
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ventilation rates Include tidal volume of the lung and breathing
frequency. Tidal volume (I.e., volume of gas Inhaled or exhaled per
respiration cycle) 1s dependent upon Individual characteristics,
Including size, age, and sex. The breathing frequency 1s based on the
degree of exertion, which can be related to general types of activities.
Data on ventilation rates as a function of these factors are provided
1n Development of Statistical Distributions or Ranges of Standard Factors
Used 1n Exposure Assessments (Anderson et al. 1984). The data presented
Include ventilation values for adult males, adult females, and children
during resting and during light, moderate, and heavy exertion.
Representative values for each activity category are presented In Table
25. Values of Inhalation rates presented 1n this table represent the
midpoint of ranges of values reported for each activity level In Anderson
et al. (1984). Resting 1s characterized by activities such as watching
television, reading, or sleeping. Light activity Includes meal cleanup;
care of laundry and clothes; domestic work and other miscellaneous
household chores; attending to personal needs and care; photography;
hobbles; and conducting minor Indoor repairs and home Improvements.
Heavy activity Includes heavy Indoor cleanup (e.g., scrubbing surfaces),
and performing major Indoor repairs and alterations (e.g., remodeling).
Maximal activity consists of vigorous physical exercise, such as weight
lifting, dancing, or riding an exercise bike. Light activity is the
level that occurs most frequently during the use of consumer products.
Additional factors that Influence inhalation rates include altitude
and body temperature. The respiratory rate increases 5 to 6 breaths per
minute per each degree Celsius rise in body temperature (ICRP 1974);
likewise, Inhalation rate increases with increasing altitude. Knowledge
of the effect of these parameters on inhalation is not likely to enhance
the quality of most exposure assessments, however.
(b) Duration of exposure. Inhalation exposure to many consumer
products can be divided into several stages, each of which may have a
different duration. For example, exposure to an aerosol product during
active use of that product may last for only seconds or minutes. Passive
exposure to direct release of that product may last for hours. And, if
the aerosol product is a coating (e.g., paint) applied to a surface
indoors, a third Inhalation exposure stage, consisting of the period
during which the chemical release rate 1s controlled by diffusion from
the solid coating, may last for weeks or months. Duration of exposure
during application of coatings to surfaces can be estimated from
information on labor production (e.g., surface area covered per unit of
time) and on the surface area to be covered. For some exposure scenarios
involving the use of pressurized aerosol products, in the absence of
better Information, it may be necessary to assume that duration of
exposure is equal to the duration of active release. For aerosol
products in which direct release occurs intermittently over the course of
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Table 25. Summary of Human Inhalation Rates for Men, Women,
and Children by Activity Level (m3/hour)a
Resting5
lightc
Moderated
Heavy6
Adult male
Adult female
Average adult^
Child, age 6
Child, age 10
0.6
0.6
0.6
0.4
0.4
1.3
1.3
1.3
1.4
1.7
2.8
2.4
2.6
2.1
3.3
7.1
4.9
6.0
2.4
4.2
aValues of inhalation rates for males, females, and children presented
in this table represent the midpoint of ranges of values reported for
each activity level in Anderson et al. (1984).
''includes watching television, reading, and sleeping.
clncludes most domestic work, attending to personal needs and care,
hobbies, and conducting minor indoor repairs and home improvements.
^Includes heavy indoor cleanup, performance of major indoor repairs
and alterations, and climbing stairs.
elncludes vigorous physical exercise and climbing stairs carrying a
load.
^Derived by taking the mean of the adult male and adult female values
for each activity level. A representative 24-hour breathing rate for
an average adult is 1.1. This value is based on the assumption that
the average adult spends 93.2 percent of the time at the light/resting
level of activity, 5.8 percent at a moderate level of activity, and 0.9
percent at a heavy level of activity. Values for the percent of time
spent at each activity level are from Methods for Assessing Exposure to
Chemical Substances in the Ambient Environment, Volume 2 of Methods for
Assessing Exposure to Chemical Substances.
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several minutes, professional judgment must be used to estimate the
duration of active use.
Most long-term passive Inhalation scenarios Involve exposure to a
chemical substance being released from a solid matrix. One possible
approach for estimating duration of passive Inhalation exposure to
chemical substances released from solid matrices 1s to assume that
release of a chemical substance will occur continuously at a constant
rate throughout the lifetime of a product. One can then also assume that
the duration of exposure 1s equivalent to the lifetime of the product.
Information regarding product lifetimes can sometimes be obtained from
the Industry that manufactures the product or the trade association that
represents the Industry that manufactures the product.
(c) Frequency of exposure. Frequency of exposure, expressed 1n
number of exposure events per year, 1s discussed 1n Section 6.2.1.
(d) Concentration of the chemical substance 1n indoor air. The
concentration of chemical substance 1n Indoor air 1s expressed 1n units
of mass of chemical substance per cubic meter of air. The method for
calculating the concentration of a chemical substance in indoor air is
determined by whether the chemical substance 1s released instantaneously,
continuously, or 1n a time-dependent manner. Examples of Instantaneous
releases Include releases of volatile chemical substances from spills of
products and short-term releases of chemical substances from aerosol
containers. Examples of continuous releases Include volatilization of
chemical substances from liquids spilled instantaneously and migration of
chemical substances from solids, such as dry paint films and plastics.
Time-dependent releases include volatilization of chemical substances
from films or coatings applied to surfaces. Usually products such as
coatings are not applied Instantaneously to surfaces. As a result, a
method is needed to account for the fact that a chemical substance may
have almost completely volatilized from the portion of the surface coated
at the beginning of the period of application, while it has only begun to
volatilize from the portion of the surface coated at the end of the
period of application. Such differences 1n the change of concentration
with time are accounted for in the equations used to calculate Indoor air
concentrations of chemical substances as a result of time-dependent
releases. Equations for calculating concentrations of chemical
substances 1n Indoor air as a result of instantaneous, continuous, and
time-dependent releases are presented in detail in Section 4.4.
Generally, the equations for calculating the average concentration of
chemical substance 1n air for a given set of exposure conditions are used
to estimate the value of CN to be used in the equations to estimate
inhalation exposure.
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6.2.3 Dermal Exposure
Despite the relative simplicity of most dermal exposure calculations,
dermal exposure presents some conceptual difficulties that are not
associated with Inhalation or 1ngest1on exposure. Exposure has been
defined earlier as the amount of substance contacting the receptor and
available for absorption. Absorption occurs when the substance crosses a
physical barrier to penetrate the tissues of the receptor. "Contact"
merely Implies that the substance has touched the body of the receptor.
"Availability" Indicates that the substance has reached (but not crossed)
the absorbtlve barrier. In the case of Inhalation and 1ngest1on, the
substance 1s taken Into a body cavity (mouth, lungs) prior to
absorption. Therefore, the substance 1s made available by swallowing or
Inhaling, and the quantity to which the receptor 1s exposed is equivalent
to the quantity inhaled or swallowed. In the case of dermal exposure,
the substance contacts only the outer surface (skin) of the receptor and
1s not taken into the body until it has penetrated the skin (I.e., after
it has been absorbed). In addition, the substance may contact the skin
but be removed before 1t can be absorbed. This makes it difficult to
define "exposure" when the receptor 1s 1n contact with large ambient
volumes of liquids or gases or with a small portion of a large solid
surface.
The sections that follow delineate methods that can be used to
estimate dermal exposure that has occurred via three pathways:
(1) exposure to a film of liquid deposited on the skin; (2) exposure to
dusts and powders deposited on the skin; and (3) exposure of skin to
chemical substances contained 1n or adhering to solid matrices. A method
for assessing exposure during immersion of skin in liquids is not
presented. A method for estimating absorbepL4fise resulting from this
pathway, however, is delineated in Sect 10(1^6.3/2^ The major problem with
attempting to assess exposure during 1mmersnrrr"o~f skin in liquids 1s that
the portion of the entire mass of the chemical substance in the solution
that 1s 1n contact with the receptor 1s not known. Obviously, the skin
of the receptor 1s not in contact with the entire volume of the
solution. A method for determining the exact thickness of the film, or
solution, in contact with the skin during the period of exposure,
however, cannot be readily determined because the physical state of the
solution in contact with the skin 1s exactly the same as the physical
state of the solution that is not in contact with the skin. Any attempt
to assess exposure for this pathway without taking into consideration
parameters needed to estimate absorbed dose 1s not very meaningful.
(1) Exposure to a Film of Liquid Deposited on the Skin. Most
significant, quantifiable dermal consumer exposure scenarios involve
liquid films on the skin. Exposure is generally expressed as mass per
year. For each use of the product, the assessor determines the mass of
liquid deposited on the skin by multiplying (1) the estimated volume of
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liquid deposited by (2) the estimated concentration of the subject
chemical substance 1n the liquid deposited on the skin. This, multiplied
by the number of annual exposures, yields total mass per year. Since
exposure is by direct physical contact, there are no fate or transport-
related parameters involved.
The product obtained by multiplying (1) the area of skin likely to be
exposed during ordinary use by (2) the film thickness is an estimate of
the volume of liquid deposited on the skin. The film thickness of a
liquid can be determined using the following equation:
Film thickness (cm) = amount of liquid retained on skin (mg/cm2)
density of liquid (g/cm3) x 1000 (mg/g)
Experimentally determined values of the amount of liquid retained on
hands are presented 1n Methods for Estimating the Retention of Chemical
Liquids on Hands. Volume 13 of Methods for Assessing Exposure to Chemical
Substances (Versar 1984a). In this study, the retention of selected
liquids on the hands of human volunteers was measured under five
conditions of exposure: (1) uptake by dry skin (initial uptake);
(2) uptake by skin previously exposed to the liquid-and still wet
(secondary uptake); (3) uptake from handling a rag; (4) uptake from spill
cleanup; and (5) uptake from Immersion of a hand in a liquid.
Initial uptake, secondary uptake, and uptake from handling a rag all
Involved contact with a cloth saturated with the liquid. The method for
determining liquid retained on the hands for each of the five
experimental conditions is as follows:
Initial uptake - A cloth saturated with liquid was rubbed over the
front and back of both clean, dry hands for the first time during
an exposure event.
Secondary uptake - As much as possible of the liquid that adhered
to the skin during Initial uptake was removed using a clean
cloth. A cloth saturated with the liquid was then rubbed over the
front and back of both hands for the second time during an
exposure event.
Uptake from handling a cloth - A cloth saturated with liquid was
rubbed over the palms of both hands for the first time during an
exposure event in a manner simulating handling of a wet cloth.
Uptake from immersion - An Individual Immersed one hand in a
container of liquid, removed the hand, then allowed the liquid to
drip from the hand back Into the container for 30 seconds (one
minute for cooking oil).
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Uptake from spill cleanup - An individual used a clean cloth to
wipe up 50 milimters (ml) of liquid poured onto a plastic
laminate countertop.
For each exposure condition, the quantity of liquid retained on the
hands was determined: (1) immediately following the exposure condition;
(2) after a partial wipe; and (3) after a full wipe (except in the case
of uptake by Immersion and uptake from spill cleanup). A partial wipe
refers to a light, quick wipe with a clean cloth. A full wipe refers to
a thorough, complete wipe with a clean cloth.
The method for determining the quantity of liquid remaining on the
exposed area of the hands, presented 1n mg/cm2, was the same for all
tests Involving use of a cloth saturated with liquid. The quantity of
liquid remaining on the exposed area of the hands immediately following
exposure (the Initial quantity) was determined by subtracting the weight
of the cloth saturated with liquid after exposure from the weight of the
cloth saturated with liquid before exposure, and dividing this difference
by the exposed skin surface area. The quantity of liquid remaining on
the exposed area of the hands after a partial wipe was determined by
subtracting the quantity removed by a partial wipe from the initial
quantity, and dividing this difference by the exposed surface area. The
quantity remaining after a full wipe was determined by subtracting the
quotient of the quantity removed by the full wipe divided by the exposed
surface area from the quantity remaining after a partial wipe.
The quantity of liquid remaining on the exposed area of the hands
immediately following immersion and spill cleanup was determined by,
first, summing the quantities of liquid removed by a partial wipe and a
full wipe. This sum was then divided by the exposed surface area. The
resulting quotient was added to the value for quantity in mg/cm2
remaining on the skin after a full wipe as determined in the initial
uptake test. To give an estimate of the total quantity of liquid
deposited by immersion or spill cleanup, the quantity of liquid remaining
after a partial wipe was determined by dividing the quantity removed by a
full wipe by the exposed surface area and adding this quotient to the
value for quantity remaining on the skin after a full wipe as determined
in the initial uptake test.
Initially six liquids were selected in this study to represent a
broad range of kinematic viscosities. The liquids used were (1) mineral
oil, (2) cooking oil, (3) water-soluble oil (bath oil), (4) oil/water
emulsion (50:50, water:water-soluble oil), (5) water, and
(6) water/ethanol (50:50). (Efforts to include additional liquids in
this study are on-going). Table 26 presents values of film thickness for
these six liquids under each of the five exposure conditions immediately
following exposure, after a partial wipe, and after a full wipe. The
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Table 26. Film Thickness Values of Selected Liquids
Under Various Experimental Conditions (10-3
Mineral Cooking Bath Oil/ Water/
oil oil oil water Water ethanol
Initial uptake
Initial film thickness
of liquid on hands 1.62 1.63 1.99 2.03 2.34 3.25
' ;" -3.^ /."'-
Film thickness after
partial wipe 0.69 0.68 0.76 1.55 1.83 2.93
. L-.i - . ,;1 /,.;;
Film thickness after
full wipe 0.21 0.16 0.21 1.38 1.97 3.12
Secondary uptake
Initial film thickness
of liquids on hands 1.43 1.51 1.80 1.60 2.05 2.95
I. I ! r --
Film thickness after
partial wipe 0.47 0.53 0.51 1.19 1.39 2.67
Film thickness after
full wipe 0.14 0.11 0.12 0.92 1.32 2.60
Uptake from handling
a rag
Initial film thickness
of liquid on palms 1.64 1.50 2.04 1.88 2.10 4.17
Film thickness after
partial wipe 0.44 0.34 0.53 1.21 1.48 3.70
Film thickness after
full wipe 0.13 0.01 0.21 0.96 1.37 3.58
103
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Table 26. (Continued)
Mineral Cooking Bath Oil/
oil oil oil water
Water/
Water ethanol
Uptake from immersion
Estimated initial film
thickness of liquid on
hand
Estimated film thickness
of liquid remaining
after partial wipe
Uptake from spill
cleanup
Estimated initial film
thickness of liquid on
hand
Estimated film thickness
of liquid remaining
after partial wipe
15.88
1.49
2- -'
1.23
0.55
11.28 12.06 9.81
G '.' ' ' >
1.59 1.51 2.42
0.73 0.89 1.19
0.51 0.48 1.36
4.99 6.55
2.14 2.93
Source: Versar (1984a)
104
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values for film thickness presented 1n this table were derived from the
experimental data on (1) amounts of liquid retained on the hands and (2)
densities of liquids from the study to assess exposure resulting from
retention of chemical liquids on hands (Versar 1985a).
The volume of liquid deposited on the skin cannot be estimated
reliably by calculations Involving quantity of product consumed per use
except 1n cases when the total amount consumed per use 1s applied
directly to the skin (e.g., cosmetic products). For example, exposure to
substances spilled on the skin has occasionally been estimated by
predicting (arbitrarily) the amount likely to be spilled (e.g., 1 ml) or
the percent of product likely to be spilled (e.g., 10 percent). This may
yield an unreaHstlcally high level of exposure, since measured film
thicknesses of liquids on the skin are on the order of magnitude of
10~3 cm (Versar 1984a). Therefore, most of a quantity of liquid
spilled on the skin would probably drip off Immediately and not
constitute genuine exposure.
An estimate of the concentration of the subject chemical substance on
the skin 1s derived by multiplying together: (1) the weight fraction (WF)
of the chemical substance 1n the product, (2) the density (DSY) of the
formulation, and (3) the dilution factor (OIL), or fraction of
formulation present as used by the consumer during the exposure event.
The basic equation for estimating annual dermal exposure via a liquid
film 1s as follows:
DEX = WF x DSY x OIL x T x AV x FQ (6-3)
where
DEX = annual dermal exposure (mg/yr)
WF = weight fraction of chemical substance 1n product (unitless)
DSY = density of formulation (mg/cm3)
OIL = dilution fraction (unitless)
T = film thickness of liquid on the skin surface (cm)
AV = skin surface area exposed per event (cm2/event)
FQ = frequency of events per year (events/yr).
The variables of equation (6-3) are determined as follows:
The weight fraction (WF) of a chemical substance in a formulation
can sometimes be obtained from the product label. Other sources
of information that may be needed to determine the weight fraction
of chemical substances in products are discussed in Section 3. A
105
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generic approach for determining the weight fraction of a chemical
substance based on knowledge of its function in a product can also
be used. This generic approach and values for the weight fraction
of functional components in select consumer products are presented
in Section 3.
The density (DSY) of a formulation can sometimes be obtained from
the product label. It can also be easily determined experimentally
if the product is available. Table 11 of Section 3 presents
experimentally determined values for the density of select
consumer products. For products not included in Table 11 it is
suggested that the density of the chemical substance making up the
largest weight fraction in the formulation be used as a default
value for the density of the product. Densities for specific
chemical substances can be obtained from references listed in
Table 9 of Section 2.
The dilution fraction (DIL) is the quotient obtained from dividing
the mass of product by the mass of substance in which this mass of
product is diluted. The dilution fraction can sometimes be
determined from information on the product label. Products that
are used undiluted are assigned a value of 1.0 for dilution
fraction.
The film thickness of a liquid on the skin (T) is the quotient
obtained by dividing the mass of liquid retained per square
centimeter (cm2) of skin surface by the density of the liquid as
used by the consumer. Table 26 presents values for film thickness
of selected liquids under various experimental conditions based on
data from Methods for Estimating the Retention of Chemical Liquids
on Hands (Versar 1984a). For assessing dermal exposure to liquids
listed in Table 26, the values presented in this table for film
thickness can be used without adjustment. To assess dermal
exposure to liquids that are not listed in this table, one can use
data for the liquid that most closely resembles the liquid for
which one is trying to assess exposure. Two physical properties
that can be used to compare liquids are kinematic viscosity and
density. Values for kinematic viscosity and density can be
obtained from references listed in Table 9 of Section 2. The
experimentally determined values for density and kinematic
viscosity for the six liquids used in the study to assess exposure
from retention of liquids on hands are presented in Table 27.
However, the error from using default values as values of film
thickness for liquids not listed in Table 26 may be considerable.
In the study to assess exposure from retention of liquids on
hands, the relationship between kinematic viscosity and mass of
liquid retained per cm2 of skin was examined. Although liquid
106
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Table 27. Experimentally Determined Values for Density and
Kinematic Viscosity of Six Selected Liquids
Liquid
Mineral oil
Cooking oil
Bath oil
Bath oil /water
Water
Water/ethanol
Density (g/cm^)
0.8720
0.9161
0.8660
0.9357
0.9989
0.9297
Kinematic viscosity (cSta)
183.0
65.4
67.2
4.19
1.02
2.55
Source: Versar (1984a).
acentistokes.
107
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retention was found to Increase with kinematic viscosity, the data
did not support a functional relationship between these two
parameters. Additional liquids must be examined to determine
whether a functional relationship exists between these two
parameters.
The exposed skin surface area (AV) can be ascertained from
judgment as to regions of the body likely to be exposed during use
of the product and from generic values for skin surface area
presented in Table 28.
(2) Exposure to Dusts and Powders Deposited on the Skin. Exposure
to dusts and powders is similar to exposure to liquid films, since it
involves the deposition of a limited, quantifiable amount of product on
the skin. The parameter, dust adherence (DA), however, replaces the film
thickness (T) and density (DSY) parameters required in equation (6-3) for
estimating dermal exposure to liquid films. The dust adherence parameter
1s expressed in units of mass per unit of skin surface area and unlike
liquid films, does not require a density factor to convert volume to mass.
The basic equation for estimating annual dermal exposure to dusts and
powders deposited on skin is as follows:
DEX = WF x AV x DA x FQ
(6-4)
DEX
WF
AV
DA
FQ
annual dermal exposure (mg/year)
weight fraction of chemical substance in product (unitless)
skin surface area exposed per event (cm2/event)
dust adherence (mg/cm2)
frequency of events per year (events/year).
Methods for determining the variables, WF, AV, and FQ, were delineated in
Section 6.2.3(1). Data on dust adherence to skin (DA) are limited. The
following experimental values for dust adherence were reported by the
Toxic Substances Control Commission of the State of Michigan (Harger
1979):
Vacuum cleaner dust sieved through an 80-mesh screen adheres to
human hands at 3.44 mg/cm2.
Dust of the clay mineral kaolin adheres to hands at 2.77 mg/cm2.
Commercial potting soil adheres to hands at 1.45 mg/cm2.
108
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Table 28. Surface Area of Body Regions3
Body region
Percent of
total surface
area
Generic
surface area (crn^)
Male Female
Male Female Average
adult
Total adults0
Head and neck
Faced
Neckd
Scalpd
Upper extremities6
Arms (both, excluding hands)
Upper arms^
Forearms^
Hands
Outstretched palm and fingersS
Lower extremities"
Legs
Thighs
Lower legs
Feet
Trunk
Total, 3-6 year-old child0
Total, 6-9 year-old child0
Total, 9-12 year-old child0
100
7.8
2.6
2.6
2.6
18.8
14.1
7.4
5.9
5.2
2.6
37.5
31.2
18.4
12.8
7.0
35.9
100
100
100
100
7.1
2.4
2.4
2.4
17.9
14.0
7.4
5. -9
5.1
2.6
40.3
32.4
19.5
12.8
6.5
34.8
100
100
100
19,400
1,180
390
390
390
3,190
2,280
1,430
1,140
840
420
6,360
5,050
1,980
2,070
1,120
5,690
7,280
9,310
11,600
16,900
1,100
370
370
370
2,760
2,100
1,250
1,000
750
375
6,260
4,880
2,950
1,940
975
5,420
7,110
9,190
11,600
18,150
1,140
380
380
380
2,975
2,190
1,340
1,070
795
400
6,310
4,970
2,470
2,005
1,050
5,555
7,200
9,250
11,600
aUnless otherwise noted, values for surface area presented in this table
are mean values reported in Anderson et al. (1984).
^Values presented in this table for average surface area are the average
of values reported or derived for males and females.
°The values for surface area of the total body presented in this table
for adults and children are based on values of surface area, reported for
the 50th percentile group in Anderson et al. (1984).
''values presented for surface area of this body region are based on the
assumption that this body region comprises one-third of the surface area
of the head and neck.
elncludes arms and hands.
^Anderson et al. (1984) do not report values for females for these body
regions; values presented were obtained by applying the percentage of
total body surface area reported for males for these body regions to the
total body surface area value for females presented in this table.
SA value of one-half the surface area of the hands is assumed.
"includes legs and feet.
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The conditions of the experiment were not reported. Since the research
was performed to support predictions of occupational exposure to the
chemical, 4, 4' - methylenebis (2-chloroaniline) (MBOCA), and since
occupational contact 1s likely to yield maximum saturation of the skin,
it 1s assumed that the experimental conditions were designed to encourage
maximum dust adherence (Versar 1982). It is not known, however, which
physical or chemical properties of a powdered substance determine the
extent of its adherence to skin; therefore, it 1s not possible to predict
the extent to which the three substances tested may represent commonly
encountered household products (e.g., powdered detergent).
Until more data become available, the value for vacuum cleaner dust
can be used as an upper limit. Substances that are UpophiHc or
surfactant, or that tend to clump in the presence of skin moisture, may
adhere to a greater extent. However, since maximum adherence is probably
rare 1n most household exposure scenarios, the value for vacuum cleaner
dust probably represents dust adherence under reasonable worst case
conditions.
(3) Exposure of Skin to Chemical Substances Contained in or Adhering
to Solid Matrices. The primary application for assessing exposure of
skin to chemical substances contained 1n or adhering to solid matrices is
the assessment of dermal exposure to substances in clothing. Exposure to
substances in clothing can be divided Into substances contaminating
clothing, such as detergent residues, and substances that are ingredients
of clothing, such as dyes. In the case of both dyes and residues, the
fraction transferred to the skin must be known to accurately assess
exposure. The tendency for chemical substances to transfer to skin
varies with the quantity of residue or dye on the fabric, the specific
chemical substance being transferred from the fabric to the skin,
physical and chemical properties of the skin surface being contacted, and
duration of contact of skin with the substance being transferred. No
experimental data regarding transfer of residues or dyes to skin have
been found. As a result of a lack of data for this parameter, arbitrary
values for percent transfer during exposure must be used.
In an assessment of consumer exposure to sodium LAS (Linear
alkanesulfonate surfactant) in detergent products, Procter and Gamble
(1981 as cited in JRB 1982b) calculated dermal absorption of sodium LAS
in detergent residues on clothing using an arbitrary transfer factor for
detergent residue of ten percent (.10) (JRB 1982b). Equation (6-5) is
suggested for estimating annual dermal exposure to chemical substances in
residues or to dyes and other chemicals on clothing in cases where the
amount of chemical substance deposited on the fabric surface is known or
can be estimated. This equation 1s adapted from an equation used by
Procter and Gamble to determine dermal absorption of sodium LAS present
in detergent residues on clothing.
110
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DEX = ADF x TF x AV x FQ x WF
(6-5)
where
DEX =
ADF =
TF =
AV =
FQ -
WF =
annual dermal exposure (mg/year)
amount of product or residue deposited on the fabric surface
(mg/cm2)
fraction of residue transferred to the skin per exposure event
(event-1)
area of skin surface exposed (cm2)
frequency of events per year (events/year)
weight fraction of chemical substance of Interest 1n product or
residue. (This value 1s equal to 1 where the product or residue
1s the chemical of Interest.)
Note that for substances formulated to adhere to fabric, such as dyes, an
arbitrary transfer factor of ten percent for a given exposure event would
probably yield a vast overestimate of dermal exposure under most
conditions. It 1s suggested that the assessor arbitrarily assume the
percent of dye that would be lost during a lifetime of wearlngs. The
assessor can then assume that a major portion of the dye would be lost
when the fabric 1s washed. The remaining fraction of dye could then be
assumed to be lost during fabric wear. Information regarding the typical
lifetime of the cloth Item and on the number of times that an Individual
would contact or wear the Item could be used to estimate the fraction of
dye transferred to the skin per event. Some of this information can be
found 1n The Generic PMN Report on Surfactants (JRB 1982b) prepared for
the Exposure Evaluation Division of the Office of Pesticides and Toxic
Substances of the U.S. Environmental Protection Agency. Trade
associations representing the textile industry may also be a source for
this information.
6.2.4 Ingestion Exposure
Methods for assessing exposure resulting from Ingestion are
delineated in this section for two pathways: Exposure due to Ingestion
of chemical substances leached out of objects used in the mouth and
exposure resulting from unintentionally swallowing liquids used in the
mouth. A method for estimating Ingestion exposure as a result of
swallowing inhaled particles too large to be respired 1s described in
Appendix A.
(1) Ingestion Exposure to Chemical Substances Leached Out of Objects
Designed to Be Used in the Mouth. Athletic mouth guards, pacifiers, and
teethers can serve as sources of chemical substances that can be
ingested. For example, children place teethers and/or pacifiers in their
mouths and suck or chew on them. In the process, chemical substances may
111
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leach or diffuse from the object Into saliva and may subsequently be
swallowed. Exposure from this pathway can be estimated 1f experimental
data on the rate of leaching of the chemical substance from the object
Into saliva are available. The basic equation for estimating annual
1ngest1on exposure to a chemical substance that has leached out of an
object used 1n the mouth 1s as follows:
ING = LR x SAO x D x F (6-6)
where
ING = annual Ingestion exposure (mass/year)
LR = experimentally determined leaching rate of the chemical
substance from the object Into saliva (mass/hr/cm2)
SAO = surface area of the object being placed In mouth (cm?)
D = duration of exposure (hours/event)
F = annual frequency of exposure events (events/year).
A major limitation of this method 1s the necessity of using experimental
data on rate of leaching of the specific chemical substance from the
object.
(2) Ingestion Exposure from Unintentionally Swallowing Liquids Used
1n the Mouth. Toothpaste and mouthwash are examples of consumer products
Intended to be used 1n the mouth but not Intended to be consumed. The
basic equation for estimating annual Ingestion exposure to chemical
substances present 1n liquids used 1n the mouth that are swallowed
unintentionally 1s as follows:
ING = WF x M x LUS x F
(6-7)
where
ING
WF
M
LUS
F =
annual Ingestion exposure (mass/year)
weight fraction of chemical substance In liquid (unltless)
mass of liquid used per exposure (mass/event)
fraction of liquid used In the mouth that Is swallowed
unintentionally (unltless)
annual frequency of exposure events (events/year).
A major limitation of this method 1s that there are no data to support
any generalization regarding the proportion of liquids used In the mouth
that may be swallowed unintentionally. Consequently, an arbitrary value
must be selected for this parameter.
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6.3 Absorbed Dose
6.3.1 Inhalation
Absorption from the lung of toxicants that are gases, volatilized
liquids, or liquid aerosols 1s usually rapid and complete, since the lung
surface 1s large (50 to 100 square meters) and blood flow to the lung 1s
high and 1n proximity to the alveolar air (10 pm) (Casarett and Doull
1975). Absorption of liquids 1n aerosols probably occurs by diffusion;
therefore, I1p1d-soluble compounds are absorbed most readily.
Partlculate matter reaching the alveoli can be removed by three major
routes: (1) direct translocatlon of the toxicant from the alveoli Into
the blood, (2) removal via the bronchi to the gastrointestinal tract, and
(3) migration via the lymphatic system (Casarett and Doull 1975).
Removal of partlculate matter via direct translocatlon of the toxicant
from the alveoli Into the blood is an Important route for soluble
compounds. Removal via the bronchi to the intestinal tract appears to be
composed of a relatively rapid clearance phase (1 day) that 1s not
affected by the nature of the toxicant and a much slower phase (days to
years) that 1s dependent on the nature of the toxicant. Particles can
penetrate the interstitial tissue of the lung and migrate via the
lymphatic system as free particles or engulfed in cells that consume
debris and foreign bodies (phagocytes). Partlculate material can remain
1n the lymphatic tissue for long periods of time. Some particulates may
remain in the alveolus indefinitely, however, in cases where lung tissue
proliferates to form a plaque or nodule around the particle.
6.3.2 Dermal
In order to be absorbed through the skin, a substance must pass
through epidermal cells, the cells of the sweat or sebaceous glands, or
hair follicles. Most substances pass through epidermal cells. Chemicals
must pass through a large number of cells: the outer densely packed
layer of horny, keratinlzed epidermal cells; the germinal layer of the
epidermis; the corium; and the systemic circulation. For lung or
gastrointestinal absorption, on the other hand, a substance need pass
through only two cells.
The first phase 'of percutaneous absorption is diffusion through the
epidermis, which is rate-limiting. The stratum corneum is much thicker
in some areas than others. The stratum corneum conjunctivum area is the
least permeable. Polar and nonpolar substances diffuse by different
molecular mechanisms. Polar substances diffuse through the outer surface
of the protein filaments of the hydrated stratum corneum, while nonpolar
molecules probably dissolve in and diffuse through the nonaqueous lipid
matrix between the protein filaments. The rate of diffusion of nonpolar
113
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substances is related to the 11p1d solubility and inversely related to
the molecular weight. The second phase 1s clearance of substance from
dermls, which is much less compact than epidermis, and passage into
circulation. The latter phase depends on blood flow, interstitial fluid
movement, lymphatics, and other factors (Casarett and Doull 1975).
Brown et al. (1984) present a comprehensive list of variables that
influence rate and amount of skin absorption. Variables such as amount
of skin surface area exposed, duration of exposure, and type of skin
exposed are acknowledged by Brown et al. (1984) to influence absorption.
Other variables reported by Brown et al. (1984) to influence absorption
are discussed below.
Hydration -
Absorption is reported to increase with increasing
hydration of the skin. If the skin 1s hydrated
(covered with perspiration, Immersed 1n water) or
the chemical substance being absorbed is in
solution, diffusion and penetration will be
enhanced. A pure liquid solvent, on the other hand,
will dehydrate skin and elicit compaction of the
stratum corneum, which will act to slow absorption
of the chemical.
Temperature - Increased skin or solute (water) temperature is
reported to enhance skin absorption capacity
proportionately.
Skin
Condition
Regional
Variability
Individual
Variability
Any damage (sunburn, cuts, wounds, abrasions) to the
stratum corneum is reported to compromise its
ability to act as a barrier against foreign
substances.
The epidermis of the hand is reported to represent a
greater barrier to penetration than the epidermis of
many other parts of the body; penetration through
the scrotum is estimated to be 100 percent.
Absorption rates are reported to vary among
individuals, and even for the same individual over
time. Variables such as age, sex, ratio of body fat
to total weight, previous exposure, nutrition, type
and amount of skin exposed, and the specific
conditions of exposure are all reported to affect
actual absorption.
114
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Physical and Factors affecting absorption are reported to Include
Chemical 11poph1"l1c1ty, polarity, volatility, molecular
Properties weight, carbon number, and solubility of the
of the chemical substance 1n the stratum corneum. The pH
Chemical of a solution 1s also reported to affect absorption
Substance - of the solution.
Vehicles and Various compounds such as alcohols, solvents, and
Accelerants - chloroform are reported to demonstrate permeability-
enhancing effects. Soaps and surfactants are also
reported to Increase skin permeability significantly.
Synerg1st1c Combinations of compounds are reported to have
Effects - greater effects on the stratum corneum and to be
absorbed more readily.
Brown et al. (1984) also reported findings from a review of the
existing literature on absorption rates of volatile solvents 1n aqueous
solutions having direct contact with skin. According to this review, for
dilute aqueous solutions, absorption of solute is directly proportional
to concentration 1n accordance with Pick's law; for pure or highly
concentrated liquids, however, this relationship is not necessarily
true. In fact, much experimental evidence exists indicating that
permeation rates are actually Increased with dilute aqueous solutions as
compared to pure liquids. Investigators reportedly attribute this effect
to the compaction and dehydration of the stratum corneum when in contact
with pure liquids, 1n addition to other factors. The implication of the
findings from this literature review is that the use of absorption rates
obtained from experiments with pure chemicals may considerably
underestimate absorption of chemical substances 1n dilute aqueous
solutions.
The following subsections present equations and describe methods that
can be used to estimate dermal absorption of chemical substances via
three exposure pathways : (1) dermal absorption from exposure to a film
of liquid deposited on the skin; (2) dermal absorption from exposure
during immersion of skin in liquids; and (3) dermal absorption during
exposure of skin to chemical substances contained in or adhering to solid
matrices. The equation for estimating dermal absorbed dose is the same
for exposure to a film of liquid on the skin and for exposure during
immersion of skin 1n liquids. For purposes of estimating dermal absorbed
dose, these two exposure pathways are grouped together. The method used
is referred to as the method for estimating absorbed dose resulting from
dermal contact with liquids. This method is presented in section (1).
The method for estimating dermal absorption during exposure of skin to
chemical substances contained 1n or adhering to solid matrices is
presented in section (2). A method for estimating absorbed dose for
115
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solids not 1n solution (I.e., dusts and powders) 1s not delineated. No
information was found in a limited Information search to predict dermal
absorbed dose for solids not in solution.
(1) Method for Estimating Dose Absorbed as a Result of Dermal
Contact with Liquids. The parameters required to estimate dermal
absorption are the same for contact with liquids via any exposure
pathway. The following equation can be used to estimate dermal
absorption resulting from contact with liquids.
ADD = C x D x AV x Kp x FQ (6-8)
where
ADD = annual dermal dose (mg/year)
C = concentration of chemical substance in the liquid medium (mg/1)
D = duration of dermal exposure (hours/event)
Kp = permeability constant (liters/cm? x hours)
FQ = frequency of exposure events per year (events/year).
The permeability constant (Kp) is influenced by such factors as the
absorption rate and concentration of the chemical substance. The
absorption rate 1s, 1n turn, determined by factors such as skin
condition, chemical and physical properties of the chemical substance,
and other factors discussed previously in Section 6.3.2. Where skin
absorption rate and concentration are known, for dilute aqueous
solutions, the permeability constant can be calculated using Fick's law.
The following equation expresses Fick's law.
Js = Kp A Cs (6-9)
where
Js = permeation rate (flux) of the solute (mg/cm2 - hr)
Kp = permeability constant (liters/cm2 - hr)
ACS = concentration difference of the solute across specified
tissue (mg/liter).
Additional experimental data are needed, however, to determine the
relationship between skin absorption rate and concentration for highly
concentrated or pure chemicals. Furthermore, more experimental data are
needed to determine at what concentration of a chemical substance the
assumption of linearity (proportionality) no longer holds true.
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(2) Method for Estimating Dermal Absorption During Exposure of Skin
to Chemical Substances Contained 1n or Adhering to Solid Matrices. The
following equation has been used by Procter and Gamble (JRB 1982b) to
estimate dermal absorption of sodium LAS present In residues on clothing
surfaces.
ADD = ADF x TF x AV x FA x FQ x WF
(6-10)
where
ADF = amount of product or residue deposited on the fabric surface
(mg/cm2)
TF = fraction of residue transferred to the skin per exposure event
(unltless)
AV = area of skin surface exposed (cm2)
FA = fraction of chemical substance absorbed (unltless)
FQ = frequency of exposure events (events/year)
WF = weight fraction of chemical substance of interest 1n product or
residue; (This value is equal to 1 where the product or
residue is the chemical of interest.)
Because of a general lack of data on the tendency for substances to
transfer to skin, an arbitrary factor must be used. In the assessment of
consumer exposure to sodium LAS in detergent residues on clothing,
Procter and Gamble used an arbitrary value of .10 to represent the
fraction of detergent residue transferred to the skin per exposure event
(JRB 1982b). No information has been found regarding arbitrary values
used 1n consumer exposure assessments to represent the fraction of dyes
transferred to skin per exposure event. The qualitative method based on
estimates of the percent of dye that would be lost during a lifetime of
wearings, described 1n Section 6.2.3(3), can be used in the absence of
quantitative data for this parameter. Another limitation of this method
is that the fraction of chemical substance absorbed over the period of
exposure must be known. This requires experimental data on dermal
absorption of chemical substances for which absorption is being
estimated. If such data are lacking for the specific chemical substance
for which absorption is being estimated, absorption data for analogues of
the chemical substance must be used, if available. Even if experimental
data on absorption are available, such data must be used with the
understanding that absorption measured during the experimental condition
may not necessarily be applicable to factors contributing to absorption
during the exposure event.
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6.3.3 Ingestlon
Absorption from the gastrointestinal tract can occur anywhere along
Its length, from the mouth to the rectum. For example, some drugs are
administered subllngually (e.g., nitroglycerine) where they are absorbed
rapidly; also, when substances are absorbed via oral mucosa, passage
through the liver 1s minimized, retarding metabolism of the substance
(Goodman and Oilman 1975).
If a substance is a weak organic acid or base, it will tend to be
absorbed by diffusion in the part of the gastrointestinal tract in which
1t exists in the most Hpid-soluble form. Since the gastric juice is
very add and the intestinal contents are nearly neutral, the Hpid
solubility of a substance can be very different in these two areas. For
example, a weak organic acid (e.g., benzole acid) is 1n the nonionized
lipid-soluble form in the stomach and therefore tends to be absorbed by
the stomach. However, a weak organic base (e.g., aniline) 1s not in the
lipid-soluble form in the stomach but 1s lipid soluble 1n the intestine,
so it tends to be absorbed 1n the intestine. Because of their large
surface area, however, the intestines will continue to absorb nonionized
chemicals present as long as the equilibrium maintains a finite
concentration of them available for absorption (Casarett and Doull 1975).
Specialized transport systems occur in the gastrointestinal tract for
the absorption of nutrients and electrolytes. For example, there are a
number of carrier systems for the absorption of certain sugars, amino
adds, and pyrimidlnes, as well as for Iron, calcium, and sodium.
Pollutants can often be absorbed by these systems, e.g., 5-fluorasil by
the pyrimidine transport system, thallium by the system that normally
absorbs iron, and lead by the system that normally transports calcium.
Some metals are absorbed by a two-step process. For example, iron first
diffuses into Intestinal cells and then is actively transported into the
blood; cobalt and manganese compete for this transport system (Casarett
and Doull 1975).
Particles can be absorbed by the gastrointestinal epithelium,
including azo dyes of nearly 100 ym diameter, and polystyrene latex
particles from an emulsion, up to 220 jjm in diameter.
The following are some of the factors that influence gastrointestinal
absorption (Casarett and Doull 1975):
Stability of substance to the acids, enzymes, and flora of the
gastrointestinal system.
Presence of compounds that increase absorption; e.g., EDTA alters
the state of membranes by removing calcium, thus increasing
permeability to bases, acids, and neutral compounds alike.
118
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Alteration of gastrointestinal motnity.
Dissolution rate 1f substance 1s Insoluble.
Size of particles.
Bulk content of food mass.
Also, complexes with other substances 1n food may decrease absorption
(Goodman and GUman 1975).
The complexity of the above factors makes 1t difficult to predict
absorption. For example, the fully Ionized quaternary ammonium compound,
pralldoxime (2-PAM), 1s not expected to be absorbed on the basis of the
pH-part1t1on hypothesis described earlier. Nevertheless, experimental
results show that 1t 1s almost completely absorbed from the gastro-
intestinal tract (Casarett and Doull 1975). Because the factors that
determine gastrointestinal absorption are highly situation-specific and
lack common quantifiable parameters, no methods for estimating
gastrointestinal absorption are delineated herein.
119
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120
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7. REFERENCES
Anderson E, Browne N, Duletsky S, et al. 1984. Development of
statistical distribution or ranges of standard factors used In exposure
assessments. Revised draft final report. Washington, DC: Office of
Health and Environmental Assessment, U.S. Environmental Protection
Agency. Contract No. 68-02-3510.
ASHRAE. 1977. American Society of Heating, Refrigerating and
Air-conditioning Engineers. ASHRAE handbook and product directory 1977
fundamentals. New York: American Society of Heating, Refrigerating and
A1r-Cond1t1on1ng Engineers, Inc.
Battelle. 1979. Formulation data for hydrocarbon-propelled aerosol
products under CPSC jurisdiction. Washington, DC: U.S. Consumer Product
Safety Commission. Contract No. CPSC-C-78-0091.
Becker D, Fochtman E, Gray A, Jacobius T. 1979. Methodology for
estimating direct exposure to new chemical substances. Washington, DC:
U.S. Environmental Protection Agency. EPA-560/13-79-008.
Bird TD, Wallace DM, Labbe RF. 1982. The porphyria, plumblsm, pottery
puzzle. JAMA 247:813-841.
Booser ER. 1981. Lubrication and lubricants. In: Kirk-Othmer
Encyclopedia of Chemical Technology. 3rd ed. New York: John Wiley &
Sons.
Brown HS, Bishop DR, Rowan CA. 1984. The role of skin absorption as a
route of exposure for volatile organic compounds (VOCs) in drinking
water. AJPH 74:479-484.
Carlson JE, VUlaveces JW. 1977. Hypersensitivity pneumonitls due to
pyrethrum. JAMA 237:1718-1719.
Casarett LJ, Doull J. 1975. Toxicology. New York, NY: MacMillan
Publishing Co. Inc.
CIS. 1986. Chemical Information System. Cliical Toxicology of
Commercial Products. Retrieval made May 1986.
Clark G. 1971. Organophosphate insecticides and behavior, a review.
Aerospace Med. 42: 735-740.
.121
-------
Cote WA, Wade WA III, Yocum JE. 1974. A study of Indoor air quality.
Washington, DC: U.S. Environmental Protection Agency. EPA-650/4-74-042.
Dixon DA, Hendrickson GL, Hammerstrom KA, et al. 1985. Methods for
assessing exposure to chemical substances. Volume 4. Methods for
enumerating and characterizing populations exposed to chemical
substances. Washington, DC: U.S. Environmental Protection Agency. EPA
560/5-85-004.
Flick EW. 1982. Handbook of paint raw materials. Park Ridge, NJ:
Noyes Publications.
Flick EW. 1984. Household, automotive and industrial chemical
formulations, 2nd ed. Park Ridge, NJ: Noyes Publications.
Fuller EN, Schettler PD, Giddings JC. 1966. A new method for prediction
of binary gas-phase diffusion coefficients. Ind. Eng. Chem. 58, 19-27.
Goodman LS, Gilman AG. 1975. The pharmacological basis of
therapeutics. 5th ed. New York, NY: MacMillan Publishing Co. Inc.
Gosselin RE, Hodge HC, Smith RP, Gleason MN. 1984. Clinical toxicology
of commercial products, 4th ed. Baltimore, MD: Williams and Wilkins Co.
Gross WF. 1970. Applications manual for paint and protective coatings.
New York: McGraw-Hill Book Company.
Harger JRE. 1979. A model for the determination of an action level for
removal of curene contaminated soil. Memorandum to P.S. Cole, Executive
Director. Lansing, MI: Toxic Substance Control Commission (October 25,
1979).
JRB. 1982a. Generic premanufacturing notification report on paint
additives (appendices). Draft report. Washington, DC: Office of Toxic
Substances, U.S. Environmental Protection Agency. Contract No.
68-01-5793.
JRB. 1982b. Generic premanufacture notification report on surfactants.
Draft report. Washington, DC: Office of Toxic Substances, U.S.
Environmental Protection Agency. Contract No. 68-01-5793.
JRB. 1983a. Generic premanufacturing notification report on paint
additives. Draft final report. Washington, DC: Office of Toxic
Substances, U.S. Environmental Protection Agency. Contract
No. 68-01-5793.
122
-------
JRB. 1983b. Generic premanufacture notification report on waxes. Draft
final report. Washington, DC: Office of Toxic Substances, U.S.
Environmental Protection Agency. Contract No. 68-01-5793.
Levin HS, Rodnltzky RL, Hick DL. 1976. Anxiety associated with exposure
to organophosphorus compounds. Arch. Gen. Psychiat. 33:225-228.
Lilis R, Green SM, Field J, Mschbein A. 1981. Paint spray gun injury
to the hand - report of an unusual source of lead poisoning. JAMA 246:
1233-1235.
L1tov1tz TL. 1983. Button battery ingestions: a review of 56 cases.
JAMA 249:2495-2500.
Lyman WJ, Reehl WF, Rosenblatt PH. 1982. Chemical property estimation
methods. McGraw Hill.
Marks JG. 1981. Allergic contact dermatitis from carbonless copy
paper. JAMA 245:2331-2332.
Marple VA, Rubow KL. 1980. Aerosol generation concepts and parameters.
In: Willeke K, (ed.). Generation of aerosols and facilities for
exposure experiments. Ann Arbor, MI: Ann Arbor. Science, pp. 3-30.
Muhletaler CA, Gerlock AJ, Shull HJ, Adkins RB. 1980. The pill bottle
desiccant: a cause of partial gastrointestinal obstruction. JAMA 243:
1921-1922.
Newmann DJ, Nunn CJ, Oliver JK. 1975. Release of individual solvents
and binary solvent blends from thermoplastic coatings. JPT. 47:70-78.
Newmann DJ, Nunn CJ. 1975. Solvent retention in organic coatings.
Progress 1n Organic Coatings. 3:221-243.
NIOSH. 1982a. National Institute of Occupational Safety and Health.
Chromium sensltization in an artist's workshop. Morb. Mort. Weekly Rep.
31:111-112, 118.
NIOSH. 1982b. National Institute of Occupational Safety and Health.
Epistaxis and liver-function abnormalities associated with exposure to
"butyl" caulk - Kentucky. Morb. Mort. Weekly Rep. 31:251-252.
PDCA. 1982. Painting and Decorating Contractors of America.
Estimating guide, 1982. Fourteenth edition. Falls Church, VA: Painting
and Decorating Contractors of America.
123
-------
Porter WK. 1983. Division of Health Sciences Laboratories, U.S.
Consumer Product Safety Commission Briefing Paper on n-hexane: Stephen
Nacht. Washington, DC: Exposure Evaluation Division, Office of Toxic
Substances, U.S. Environmental Protection Agency.
Randall FJ, Dwyer SG. 1982. "Polishes" in Kirk-Othmer encyclopedia of
chemical technology, Volume 18. Grayson M, Eckroth D (eds.). New York,
NY: Wiley Interscience.
Reid RC, Prausnltz JH, Sherwood TK. 1977. The properties of gases and
liquids. 3rd edition. New York, NY: McGraw-Hill Book Company.
Repace JL, Lowrey AH. 1980. Indoor air pollution, tobacco smoke, and
public health. Science. 208:464-472.
Roueche B. 1971. The orange man. New York: Little Brown and Co.
Sandifer SH, Keil JE, Mnkela JF, Gadsden RH. 1972. Indust. Med. 4(5):
9-12.
Schurr GG. 1981. Paint. In: Kirk-Othmer Encyclopedia of Chemical
Technology (Volume 16). 3rd edition. Grayson M, Eckroth D (eds.). New
York: John Wiley & Sons.
Schwope AD, Lyman WJ, Reid RC. 1985. Methods for assessing exposure to
chemical substances. Volume 11. Methods for Estimating the Migration of
Chemical Substances from Solid Matrices. Washington, DC: U.S.
Environmental Protection Agency. EPA 560/5-85-015.
Stricof R, Morse D, Rothenberg R. et al. 1983. Illness associated with
exposure to mothballs. Morb. Mort. Weekly Rep. 32:34-35.
Sutter SL, Johnston JW, Mishima J. 1982. Investigation of
accident-generated aerosols: releases from free fall spills. Am. Ind.
Hyg. Assoc. J. 43(7):540-544.
Treybal RE. 1968. Mass transfer operations. McGraw Hill.
Trincher RC, Rissing JP. 1983. Contamination of potable water by phenol
from a solar water tank liner. Morb. Mort. Weekly Rep. 32:493-494.
USEPA. 1984. U.S. Environmental Protection Agency. Computer printout
(CIS): Updated product formulations from clinical toxicology of
commercial products (CTCP). Retrievals made Nov, Dec 1983, and Jan, Feb
1984. Washington, DC: U.S. Environmental Protection Agency.
124
-------
Versar. 1982. Exposure assessment for 4,4'-methyleneb1s
(2-chloroan1l1ne) (MOCA). Washington, D.C.: U.S. Environmental
Protection Agency. Contract No. 68-01-6271.
Verar. 1984a. Methods for assessing exposure to chemical substances.
Volume 13. Methods for estimating the retention of chemical liquids on
hands. Washington, DC: U.S. Environmental Protection Agency. EPA
560/5-85-017.
Versar. 1984b. Methods for assessing exposure to chemical substances.
Volume 12. Methods for Estimating Concentrations of Chemicals In Indoor
A1r. Washington, DC: U.S. Environmental Protection Agency. EPA
560/5-85-016.
Versar. 1984c. Experimental densities of selected consumer products.
Unpublished.
Versar. 1985. Exposure assessment for polychlorinated blphenyls
(PCBs): Incidental production, recycling, and selected authorized uses.
Appendix A: generic exposure scenarios. Final report. Washington, DC:
Office of Toxic Substances, U.S. Environmental Protection Agency.
Contract No. 68-01-6271.
Versar. 1986. Standard scenarios for estimating exposure to chemical
substances during use of consumer products. Unpublished. Washington,
DC: U.S. Environmental Protection Agency. EPA Contract 68-02-3968.
Wills JG. 1980. Lubrication fundamentals. New York: Marcel Dekker,
Inc.
Welty JR, Wicks CE, Wilson RE. 1976. Fundamentals of momentum, heat and
mass transfer. New York: John WHey & Sons.
125
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126
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X " *
APPENDIX A
Method for Estimating Inhalation Exposure to Participates
Discharged from Consumer Products
127
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(1) Introduction. Airborne participates in the volume of inhaled
air have several possible fates. Particles orglnally in the volume of
inhaled air may not even enter the respiratory system. The aspiration
efficiency (the fraction of particles originally in the volume of Inhaled
air that enters the nose or mouth) depends on particle size, air
velocity, inhalation flow rate, and whether nose or mouth breathing is
used. When averaged over all wind directions for winds ranging from 0.75
m/sec to 2.75 m/sec (typical conditions), the maximum aspiration
efficiencies for particle sizes of 1 urn, 5 urn, and 10 urn are 100 percent,
85 percent, and 70 percent, respectively. Aspiration efficiency drops
slowly for particle sizes larger than 10 urn; aspiration efficiencies for
particles 30 urn and 60 urn in diameter are 50 percent and 35 percent,
respectively (Hinds 1982).
Once inhaled, particles may undergo respiratory tract deposition or
they may be exhaled without deposition. Total deposition, as the term is
used here, is defined as the average probability of an inspired particle
touching a surface of the respiratory tract and thereby being deposited
(Heyder et al. 1980b). The respiratory tract may be divided into three
deposition regions, based on the physical processes governing deposition
and the ultimate fate of deposited particles. Deposition in the head
region (i.e., nose, mouth, pharynx, and larynx) is the result of
sedimentation and impaction (Hinds 1982). This region effectively
filters out all inhaled particles greater than 10 urn 1n diameter, and a
large number of particles in the 1 urn to 10 urn range. The
tracheobronchial region, which comprises the airways from pharynx to
terminal bronchioles, traps many smaller particles in the 0.01 urn to 10
urn size range by impaction and sedimentation (Meyer 1983, Hinds 1982).
Particles 0.01 urn to 10 urn in diameter that pass through the bronchioles
are available for deposition via diffusion and sedimentation in the
alveolar region of the lungs. Particles deposited in the head and
tracheobronchial regions are either cleared to pharynx and swallowed,
thus available for indirect ingestion exposure via the gastrointestinal
tract, or are expelled with sputum. Thus, of the mass of inhaled
partlculates, only the respirable particles (i.e., particles small enough
to reach the alveolar region) are available for exposure via the lungs.
Most exposure assessments have neglected to distinguish between
Inhaled chemicals destined for the lungs and inhaled chemicals destined
for the gastrointestinal tract. Equation (A-l) below represents the
traditional approach to assessment of inhalation exposure.
EI = I > C(t)dt (A-l)
where
Ej = inhalation exposure (mass/time)
I = inhalation rate (volume/time)
t = duration of exposure (time)
Cj. = concentration of chemical in air as a function of time
(mass/volume).
128
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While the traditional approach 1s suitable for chemicals in gaseous
or vapor form and as a model for "worst case" exposure to chemicals in
particulate form, a more refined approach, which distinguishes between
pulmonary and gastrointestinal exposure to partlculates, will enhance the
precision of both exposure and risk assessments. Therefore, the methods
presented in this Appendix will depart from the traditional approach by
providing algorithms that allow for separate estimates of the pulmonary
and gastrointestinal tract components of Inhalation exposure for inhaled
partlculates, to be used at the discretion of the exposure assessor. It
should be stressed that, despite the distinction made here between
pulmonary exposure and gastrointestinal exposure, these methods do not
include calculation of absorbed dose. The factors that govern the extent
to which Inhaled substances are absorbed are largely chemical-specific;
therefore, the prediction of absorbed dose is not currently amenable to
the generic approach that 1s the foundation of this report.
(2) Exposure Calculation. Assessment of Inhalation exposure to
consumer products involves finding a simple or complex solution to
equation (A-l) and Identifying appropriate parameter values. In
practice, the algorithm used to calculate inhalation exposure 1s usually
an Integrated and simplified version of equation (A-l), often
incorporating simplifying assumptions about the change in concentration
with time. (See Section 4 for a detailed discussion of methods for
calculating concentration.) In many cases, exposures can be calculated
using an average concentration for a given period of time; exposures from
several such consecutive time periods can be summed to estimate total
inhalation exposure to a given product. The simplified version of
equation (A-l) is presented below.
IHX = IR x DU x FQ x CN (A-2)
where
IHX = quantity inhaled (mg/yr)
IR = inhalation rate (m3/hr)
DU = duration of exposure event (hours)
FQ = frequency of exposure (events per year)
CN = Indoor air concentration of a given constituent (mg/m3).
If precise estimates of exposure are desired, modifications of the
above equation can be made for chemicals present in air as particulates,
to account for the previously mentioned variation 1n both total and
regional deposition as a function of particle size. In this case, the
total exposure to inhaled particulates is calculated using equation
(A-3), which includes a term (TDF) that accounts for the fraction of
Inhaled particulates deposited in the respiratory tract. (Note that
aspiration efficiency is assumed to be 100 percent, a worst case
assumption.)
129
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IHX = IR x DU x FQ x CN x TDF (A-3)
where
IHX, IR, DU, and FQ are as used 1n equation (A-2).
TDF = total deposition fraction, which is the weight fraction of
inhaled particles deposited in the respiratory tract.
The total exposure to particulates calculated in equation (A-3) can
be divided into the pulmonary region exposure (IHXp) and the gastro-
intestinal tract exposure (IHXg), using equations (A-4) and (A-5),
respectively. This partitioning of inhalation exposure is an option that
may be worthwhile for chemicals whose effects depend on the mode of entry
into the body.
IHXp = IR x DU x FQ x CN x RF
IHXG = IR X DU X FQ X CN X NRF
(A-4)
(A-5)
where
RF =
respirable fraction, which is the weight fraction of all
inhaled particles deposited in the pulmonary airspaces
NRF = nonrespirable fraction, which is the weight fraction of all
inhaled particles deposited in the head or tracheobronchial
regions.
For the purpose of this analysis, it is assumed that all of the
inhaled particulates that are deposited in the respiratory tract are
destined for either the lungs or the gastrointestinal tract, as shown in
equation (A-6). (No information was available on the fraction of
material initially deposited in the head or tracheobronchial region that
might be subsequently expelled with sputum.)
IHX = IHXp + IHX(j
(A-6)
(3) Inhalation Exposure Parameters. Information on the
parameters included in equations (A-2) through (A-6) above is presented
in this subsection. Parameters are listed in alphabetical order.
(a) CN. Chemical concentration in the air, expressed in
mg/m3, can be calculated in a number of ways, as discussed in
Section 4. Depending on the particular exposure scenario, the
concentration may be taken as constant or as changing over the period of
exposure. Among the variables that affect concentration are total
quantity of chemical released, release rate of the chemical, room size,
ventilation rates, and time lapse.
. 130
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(b) DU. Duration of exposure is discussed 1n general 1n
Section 6.2. An Inhalation exposure event can be measured in seconds,
minutes, or hours. Inhalation exposure to many consumer products can be
divided Into several stages, each of which may have a different
duration. For example, exposure to an aerosol product during active use
may last for only seconds or minutes. Passive exposure to direct release
of that product may last for hours. And, 1f the aerosol product Is a
coating (e.g., spray paint) applied to an object that remains Indoors, a
third Inhalation exposure stage, consisting of the period during which
the chemical release rate 1s controlled by diffusion from the solid
coating, may last for weeks or months.
There are several ways to obtain estimates of duration for Inhalation
exposure scenarios. Methods used for estimating the duration for an
Inhalation exposure scenario are determined by whether the assessor is
concerned primarily with exposure during active use of the product or
with exposure during passive use, or both. A method for estimating
duration of active exposure during the application of coatings to
surfaces is presented in detail 1n Section 3.1 of this volume. In some
cases, estimates of duration can be made based on literature values or
professional judgment. Additional general guidelines to follow for
estimating duration are presented in Section 6.2.1 of this volume.
(c) FQ. Frequency of exposure, expressed 1n exposure events
per year, is discussed in Section 6.2.1.
(d) IHX. Total individual inhalation exposure, expressed in
mg/year, refers specifically to the quantity of inhaled particulates that
are likely to be deposited in the respiratory tract. Depending on the
particle size distribution of the inhaled aerosol, this quantity may be
equal to or significantly less than the quantity inhaled. In practice,
there may not be sufficient data on particle size distribution to
estimate the quantity deposited in the respiratory tract; in such cases,
100 percent deposition can be assumed as a worst case.
(e) IHXp. Pulmonary Inhalation exposure, measured in terms
of mg/year, 1s the quantity of inhaled particulate material that is
available for alveolar absorption. (This is to be distinguished from the
quantity that is absorbed across the alveolar membrane, which is not
addressed in this report.) IHXp depends on the respirable fraction RF
(see (1) below), which in turn depends on the particle size distribution
of the Inhaled aerosol.
(f) IHXg. Gastrointestinal inhalation exposure, measured as
mg/year, is the quantity of inhaled particulate material that is
initially deposited in the head or tracheobronchial region, thus subject
to gastrointestinal rather than pulmonary exposure. As with IHXp,
IHXQ depends on the particle size distribution of the inhaled aerosol
131
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via a deposition factor, NRF (see below). The portion of IHXg that 1s
expelled from the body via nose-blowing or expectoration, and thus not
available for exposure, is assumed to be insignificant for the purpose of
these exposure calculations.
(g) IR. Inhalation rate, expressed 1n m3/hr, is discussed in
Section 6.2.2.
(h) NRF. The nonrespirable fraction is a unitless parameter,
ranging from 0 to 1, that represents the weight fraction of inhaled
particulates initially deposited in the head and tracheobronchlal regions
of the respiratory tract, and thus not available for exposure via the
lung. Particles deposited in these areas are cleared to the
gastrointestinal tract. Values for NRF of particulates discharged from
select consumer products are presented in Table 29 at the end of Appendix
A. NRF 1s calculated by using equation (A-7), provided that the
supporting data on particle size distribution are available,* If there
are Insufficient data for equation (A-7) but the mass median diameter is
known, a less reliable estimate of NRF can be made using the ICRP model
1n Figure 3 (see discussion of TDE below).
n
NRF = I [(TDE1 - PDEi) x WF^j ] (A-7)
1=1
TDEj = total respiratory tract deposition rate for particles
within aerodynamic diameter size class 1 (a unitless
fraction varying from 0 to 1)
PDE^ = pulmonary deposition rate for particles within
aerodynamic particle diameter size class i (a unitless
fraction)
WF} = the weight fraction of particles in aerodynamic diameter
size class 1 (a unitless fraction).
Detailed information on the applications and data sources for each of
the parameters in equation (A-7) is provided below:
TDE. The fraction of inhaled particles in a given size range that
1s deposited in the respiratory tract has been studied both
theoretically and experimentally. Theoretical models such as the
International Commission on Radiological Protection's (ICRP) Task
*Note: Equation (A-7) could just as easily be written as:
NRF = TDF - RF
See (j) for a discussion of TDF and (1) for a discussion of RF.
132
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Group on Lung Dynamics Model, presented as Figure 3, have been
used 1n the past to determine deposition. There are discrep-
ancies, however, between the ICRP model, which relates deposition
to particle mass median diameter (I.e., the diameter below which
lies 50 percent of the mass of the particles), and more recent
experimental data relating deposition to aerodynamic diameter.
For this reason, exposure estimates should be based on the
experimental data rather than the ICRP model 1n cases where
sufficient data on particle size distribution are available.
Total deposition in the respiratory tract is the sum total of
deposition in the head, tracheobronchial, and pulmonary regions.
Total deposition depends on particle diameter, particle density,
total volume, breathing rate, and type of breathing used (nose or
mouth) (Heyder et al. 1980b). As discussed in Section (1),
particles ranging from 1 urn to 100 urn are retained in the head
region, and particles in the 0.01 urn to 10 urn range are absorbed
in the tracheobronchial tract or proceed Into the pulmonary cavity.
The relationship between total respiratory tract deposition and
aerodynamic particle size 1s given in Figure 4, based on
information or data reported in Heyder et al. (1974), Heyder et
al. (1980a), Heyder et al. (1980b), Hinds (1982), Stahlhofen et
al. (1980), and Meyer (1983). It should be noted that some of the
information reported in these sources 1s conflicting; Figure 5
represents a synthesis of the Information in all of these
sources. Two graphs are given in Figure 4, one representing
deposition under "typical" breathing conditions (i.e., normal nose
breathing during rest or light activity), the other representing
"maximum" deposition (i.e., maximum values reported in the
reviewed literature). Information on deposition for particles
smaller than 0.1 urn is sparse and conflicting. Deposition of
these small particles occurs largely by diffusion; thus, it cannot
be clearly expressed as a function of aerodynamic particle
diameter (Heyder et al. 1980a). A comparison of Figure 4 with
Figure 5 Indicates that tracheobronchial deposition accounts for
the majority of the total deposition of smaller particles in this
size range; this enhancement of tracheobronchial deposition can be
attributed to the rapid Brownlan motion (Hinds 1982). A large
fraction of particles smaller than 0.05 urn may be exhaled unless
they dissolve or react with or on the surface (Meyer 1983). Total
deposition of particles in the 0.1 urn to 1 urn size range, where
sedimentation becomes important in addition to diffusion, is lower
than for smaller particles. Deposition via impaction in the head
region becomes increasingly important for particles in the 1 urn to
10 urn size range; total deposition approaches 100 percent for
particles larger than about 3 urn.
133
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0.8
c
5
0.4
o
o
02
Nasopharynx
-2-1 012
Particle mass median parameter (ym)
Figure 3. ICRP Model of Regional Respiratory Tract Deposition
as a Function of Particle Size.
Source: Meyer 1983.
134
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CO
en
1.0-
.9 -
.8 -
.7 -
.6 -
O
Q.
til
a
.4 -
3 -
.2 -
1 -
01
II I I I 11 r
05 .1
I I
AERODYNAMIC PA«1ICLE OlAMElbR (pm)
I III
5
10
TYPICAL/NOSE BREATHING
MAXIMUM VALUES
FIGURE 4 . TOTAL DEPOSITION OF PARTICULATE^ IN THE RESPIRATORY
TRACT AS A FUNCTION OF PARTICLE flZE
-------
CO
en
10 -
0.9 -
I I I I I I I
01 -
001
AERODYNAMIC PARTICLE DIAMETER (pm)
TYPICAL/NOSE BREATHING
MAXIMUM VALUES
FIGURE 5. PULMONARY DEPOSITION OF PARTICIPATES AS A
FUNCTION OF PARTICULATE SIZE
-------
PDE. The fraction of Inhaled particles 1n a given size range
subject to pulmonary deposition has been studied both
theoretically and experimentally. The discussion of discrepancies
between the ICRP model (Figure 3) and experimental data 1n
relation to estimates of the parameter TOE applies equally well to
the parameter POE. A summary of the relationship between
particle size and pulmonary deposition 1s given 1n Figure 5 based
on data or Information reported 1n Heyder et al. (1974), Heyder et
al. (1980a), Heyder et al. (1980b), Hinds (1982), Stahlhofen et
al. (1980), and Meyer (1983). The reader should be aware that
other factors 1n addition to particle size affect alveolar
deposition; these Include breathing characteristics, such as type
of breathing (nose vs. mouth), breathing rate, and tidal volume.
Under constant breathing conditions, however, there 1s a clear
relationship between aerodynamic particle diameter and pulmonary
deposition for particles larger than about 0.1 urn. The data
summarized 1n Figure 5 are discussed 1n more detail below.
Figure 5 Includes two graphs, one representing deposition to be
expected under typical conditions (I.e., nose breathing during
light activity) and the other representing the highest deposition
values reported 1n the reviewed literature. No distinction
between "typical" and "maximum" 1s provided for particles less
than about 0.3 urn, because the Information on deposition 1n this
size range 1s sparse. The PDE values corresponding to aerodynamic
particle diameters less than 0.1 urn 1n Figure 5 were taken from
Heyder et al. (1980a) who did not specify the origin of the data.
The trend 1n decreasing pulmonary deposition with decreasing
particle size 1n the 0.05 urn to 0.01 urn range 1s presumably
related to enhanced tracheobronchlal deposition for this size
range (see TOE, above). Pulmonary deposition between 0.1 urn and 1
urn 1s about 20 percent, Independent of particle size (Hinds
1982). Pulmonary deposition peaks again around 2.5 urn to 3 urn and
approaches 0 around 6 to 7 urn. Particles larger than 1 urn are
Increasingly filtered out by the head region. This explains the
decrease 1n pulmonary deposition with Increasing particle size for
particles larger than about 3 urn. Figure 5 suggests that 0.75
might be used as a worst case estimate of PDE 1n cases where
detailed particle size distribution data are not available.
WF. The weight fraction of aerosol particles in a given
aerodynamic diameter size range 1, must be known or estimated 1n
order to estimate regional deposition in the respiratory tract.
Because of the limited availability of particle size distribution
Information, WF will often be the stumbling block in exposure
calculations Involving inhaled partlculates. Particle size
distribution information 1s available for a number of aerosol can
products and can be found in various trade association journals.
137
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Typical particle size distributions for other types of
participates (e.g., asbestos fibers, household dust, cigarette
smoke) generated during the use of consumer products have, In some
cases, been measured 1n health-related studies. A complete
particle size distribution may not be necessary for crude worst
reasonable case exposure calculations. Considerable professional
judgment will be needed by the exposure assessor 1n converting
available Information on particle size distribution to WF in
equation (A-7). In cases where the only Information available 1s
the mass median diameter, this parameter can be used 1n
conjunction with data 1n Figure 3 to estimate respiratory tract
deposition.
(1) RF. The resplrable fraction 1s the fraction of Inhaled
aerosol particles likely to be deposited In the pulmonary airspaces.
This parameter, which ranges from 0 to about 0.7, 1s a function of the
particle size distribution of the Inhaled aerosol and can be calculated
using equation (A-8), providing that sufficient data are available. A
less accurate estimate of RF can be made using the model given 1n Figure
3 1n conjunction with the mass median diameter (see discussion under TOE
1n (h), above).
n
RF = I (PDE1 X WFi) (A-8)
1=1
A detailed explanation of the parameters used 1n equation (A-8)
can be found under NRF (see (1)). It should be obvious that the data
provided 1n Figure 5 are essential In calculating RF. Values of RF of
partlculates discharged from selected consumer products are presented In
the Table at the end of Appendix A.
(j) TDF. The total deposition fraction 1s the weight fraction of
all Inhaled particles deposited 1n the respiratory tract. This parameter
can be calculated using equation (A-9), providing that the particle size
distribution 1s known. A cruder estimate of TDF can be made using the
model given In Figure 3 In conjunction with the mass median diameter (see
discussion under TDE 1n (h), above).
n
TDF = I (TDEi X WFi) (A-9)
1=1
A detailed discussion of these parameters is included in the
discussion of NRF (see (i), above). It must be noted that data on TDF
particulates discharged from selected consumer products are not presented
in the table at the end of Appendix A. In all cases where nonrespirable
and respirable fractions of particulates were calculated or estimated, a
138
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maximum value for TDF of 1.0 was used. The total deposition, or average
probability that an Inspired particle may undergo respiratory tract
deposition, was not considered 1n this analysis. Precise data on
aspiration efficiency according to particle size are needed to accurately
quantify the TOP of partlculates. Aspiration efficiency, or the fraction
of particles originally 1n the volume of Inhaled air that enters the nose
or mouth, 1s dependent on a number of factors. These Include particle
size, air velocity, Inhalation flow rate, and whether nose or mouth
breathing 1s used. To circumvent the difficulties Involved 1n attempting
to quantify each of these factors, as a worst case, the aspiration
efficiency was assumed to be 100 percent. As a result, a maximum value
for TDF of 1.0 1s suggested for use 1n all calculations requiring this
parameter. The value of 1.0 for TDF, however, represents a worst case
assumption.
139
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Table 29. Values of Respirable and Nonrespirable Fraction of Particulates for Selected Consumer Products (continued)
Aerosol product
Nonrespirable fraction
Minimum Typical Maximum
Respirable fraction
Minimum Typical Maximum
Comments
Deodorant/antiperspirant 0.66
Hairspray
Furniture polish
0.66
0.5
General cleaner/
disinfectant
Insecticide, home
and garden
Insect repel 1ant
0.5
0.88 0.96 0.04 0.12 0.34 Calculated using typical and maximum pulmonary
deposition factors presented in Figures 4 and 5 and
available data on particle size distribution of
particulates discharged from deodorants/
antiperspirants.3
0.88 0.97 0.03 0.12 0.34 Calculated using typical and maximum pulmonary
deposition factors presented in Figures 4 and 5 and
available data on particle size distribution of
particulates discharged from hairspray.b
0.82 1.0 7.6x10"^ 0.18 0.50 Calculated using typical and maximum pulmonary
deposition factors presented in Figures 4 and 5 and
available data on particle size distribution of
particulates discharged from aerosol furniture
polish.0
0.87 0.97 0.03 0.13 Calculated using typical and maximum pulmonary
deposition factors presented in Figures 4 and 5 and
available data on particle size distribution of
particulates discharged from aerosol disinfectant.01
0.92 0.98 0.02 0.08 Calculated using typical and maximum pulmonary
deposition factors presented in Figures 4 and 5 and
available data on particle size distribution of
particulates discharged from products designed for use
on flying insects.6
1.0 0 0.5 Values are estimates based on ranges of values
calculated for other aerosol products.
I"
-------
Table 29. Values of Respirable and Nonrespirable Fraction of Particulates for Selected Consumer Products
Aerosol product
Lubricant
Oven cleaner
Pet pesticide
Room deodorizer
Nonrespirable fraction
Minimum Typical Maximum
0.5
0.5
0.64
1.0
1.0
1.0
0.92
Respirable fraction
Minimum Typical Maximum
0.5 0.5 0.5
0.5
0 0.5
0.08 0.36
Garments
Values are estimates based on ranges of values
calculated for other aerosol products.
Values are estimates based on ranges of values
calculated for other aerosol products.
Values are estimates based on ranges of values
calculated for other aerosol products.
Calculated using typical and maximum pulmonary
Spray starch
Suede cleaner/polish
Fabric protector
Home spray paint
0.5
0.78
Automotive touch-up paint 0.78
0.52
0.92
0.92
1.0
0.94
0.83
6x10-
0.06
0.17
0.48
0.08
0.08
deposition factors presented in Figures 4 and 5 and
available data on particle size distribution of
particulates discharged from aerosol room
deodorizer.f
Calculated using typical and maximum pulmonary
deposition factors presented in Figures 4 and 5 and
available data on particle size distribution of
particulates discharged from spray starch.9
0.5 Values are estimates based on ranges of values
calculated for other aerosol products.
Calculated using typical and maximum pulmonary
deposition factors presented in Figures 4 and 5 and
available data on particle size distribution of
particulates discharged from aerosol fabric
protector."
0.22 Calculated using typical and maximum pulmonary
deposition factors presented in Figures A-2 and A-3
and available data on particle size distribution of
particulates discharged from spray paints.1
0.22 Values are assumed to be the same as those for home
spray paint.
-------
APPENDIX A - REFERENCES
Heyder J, Armbruster L, Gebhart J, Greln E, Stahlhofen W. 1974. Total
deposition of aerosol particles 1n the human respiratory tract for nose
and mouth breathing. J. Aerosol Science 6:311-328.
Heyder J, Gebhart J, Stahlhofen W. 1980a. Inhalation of aerosols:
particle deposition and retention. In: Wllleke K, ed. Generation of
aerosols and facilities for exposure experiments. Ann Arbor, MI: Ann
Arbor Science, pp. 65-104.
Heyder J. Gebhart J, Rudolf G, Stahlhofen W. 1980b. Physical factors
determining particle deposition 1n the human respiratory tract. J.
Aerosol Science 11:505-515.
Hinds WD. 1982. Aerosol technologyproperties, behavior, and
measurement of airborne particles. New York, NY: John Wiley & Sons.
ICRP. 1974. International Commission on Radiological Protection.
No. 23. Report of the task group on reference man. New York: Pergamon
Press.
Meyer B. 1983. Indoor air quality. Reading, MA: Addison-Wesley
Publishing Company, Inc.
Mokler BV, Wong BA, Snow MJ. 1979a. Respirable partlculates generated
by pressurized consumer products. I. Experimental method and general
characteristics. Am. Ind. Hyg. Assoc. J. 40(4):330-338.
Mokler BV, Wong BA, Snow MJ. 1979b. Respirable particulates generated
by pressurized consumer products. II. Influence of experimental
conditions. Am. Ind. Hyg. Assoc. J. 40(4):339-347.
Sciarra JJ, McGinley P, Izzo L. 1969. Determination of particle size
distribution of selected aerosol cosmetics. I. Hair sprays. J. Soc.
Cosmetic Chemists 20:385-394.
Sciarra JJ, Stoller L. 1974. The science and technology of aerosol
packaging. New York, NY: John Wiley & Sons, Inc.
Stahlhofen W, Eckhard B, Gebhart J, Heyder J, Stuck B. 1980.
Measurement of the extrathoracic, tracheobronchial and alveolar
deposition of aerosol particles in the human respiratory tract.
J. Aerosol Science 11(3):234.
Vos OKD, Thomson DB. 1974. Particle size measurement of eight
commercial pressurized products. Powder Tech. 10(3): 103-109.
Wells AB, Alexander DJ. 1976. Determining resplrable fraction of
aerosols. Aerosol Age 21(11):20-24.
143
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144
-------
APPENDIX B
Simmons Market Research Bureau (SMRB) Reports
145
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APPENDIX B - SIMMONS MARKET RESEARCH BUREAU (SMRB) REPORTS
The tables Included in this Appendix are a guide to the individual
SMRB reports (volumes) and the products covered by each volume. The
following are the tables included in this Appendix:
Table 30. SMRB reports (1983) by Volume
Table 31. Products Listed in SMRB Reports (1983) by Product Category
146
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Table 30. SMRB Reports (1983) by Volume
Volume Title
P-l . Automobiles
P-2 Cycles, Trucks, Vans & Tires
P-3 Automotive Products and Services
P-4 Travel
P-5 Banking, Investments, Memberships,
Public Activities & Contribution
P-6 Insurance & Credit Cards
P-7 Books, Records, Tapes, Stereo & TV
P-8 Appliances, Sewing & Garden Care
P-9 Home Furnishings & Home Improvements
P-10 Sports & Leisure
P-ll Restaurants, Stores & Grocery Shopping
P-12 At Home Shopping, Yellow Pages,
Florists & Telegrams
P-13 Jewelry, Wristwatches, Luggage,
Binoculars, Pens & Pencils and Hen's
Apparel
P-14 Women's Apparel
P-l5 Tobacco Products & Photography
P-16 Distilled Spirits & Mixes
P-l7 Malt Beverages & Wine
P-18 Coffee, Tea, Milk, Soft Drinks, Juices
& Bottled Water
P-l9 Dairy Products, Spreads, Cookies,
Desserts, Baking & Bread Products
P-20 Cereals, Rice, Pasta, Pizza, Mexican
Foods, Fruits & Vegetables
P-21 Soup, Meat, Fish, Poultry, Condiments
& Dressings
P-22 Chewing Gum, Candy & Snacks
P-23 Soap, Laundry & Paper Products &
Kitenet Wraps
P-24 Household Cleaners, Room Deodorizers &
Pet Foods
P-25 Health Care Products & Remedies
P-26 Oral Hygiene Products, Skin Care &
Deodorants
P-27 Hair Care & Shaving Products
P-28 Women's Beauty Aids, Cosmetics &
Personal Products & Beauty Salons
P-29 Games & Toys, Children's & Babies'
Apparel & Specialty Products
P-30 Relative Volume of Consumption
147
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Table 31. Products Listed in SMRB Reports (1983)
by Product Category
Product Category
Volume
Product
APPAREL - CHILDREN'S &
BABIES'
APPAREL - MEN
APPAREL - WOMEN
(P-29) Clothing
Diapers/Cloth, Disposable
Jeans or Dungarees
Outerwear
Shoes
Sleepwear
Suitwear
Underwear
(P-13) Clothing Bought for a Woman
Coats
Jackets
Jeans & Slacks
Shirts
Shoes, Boots & Sneakers
Sports Apparel
Suits
Sunglasses
Sweaters
(P-14) Blouses & Shirts
Clothing Bought for a Han
Coats
Dresses
Hosiery
Jeans & Slacks
Lingerie
Shoes, Boots & Sneakers
Ski & Tennis Clothes
Skirts
Suits
Sunglasses
Sweaters
Swimsuits
Warm-up Suits
148
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Table 31. (Continued)
Product Category
Volume
Product
APPLIANCES & DURABLES:
Cal cu 1 ators/Typewr Hers
Household Appliances &
Durables
Kitchen Appliances &
Durables
(P-8) Bought in Last 12 Months/For
Whom/Amount Spent
Desk Top Calculator
Pocket or Hand-Held Electronic
Calculator
Typewriter, Electric Portable
(P-8) Bought in Last 12
Months/Decision Maker
Air Conditioner, Separate Room
Burglar Alarm System
Ceiling Fan
Electric Air Purifier
Electric Broom
Electric Clothes Dryer
Gas Clothes Dryer
Grills: Gas, Electric,
Charcoal
Home Computers, Brands and Use
Room Heater, Portable
Room Heating System, Separate
Room Dehumidifier, Separate
Room Humidifier, Separate
Sewing Machine
Smoke/Fire Detector
Stationary Bicycle
Videocamera
Washing Machine, Automatic
Water Purifier or Filter
(P-8) Bought in Last 12 Months/
Decision Maker
Automatic Dishwasher
Blender, Electric
Canning Oars & Lids
Coffee Maker
Food Processor, Electric
Food Dehydrator
Fry Pan, Electric
149
-------
Table 31. (Continued)
Product Category
Volume
Product
APPLIANCES & DURABLES:
Kitchen Appliances &
Durables (conf)
Personal Appliances
Power Equipment &
Hand Tools
(P-8) Garbage Disposal
Home Freezer, Separate
Juicer, Electric
Metal Cookware Set
Mixer, Electric
Oven:
Microwave
Self-Clean i ng/Cont i nuous
-Cleaning
Pressure Cooker
Refrigerator, Electric
Steam Cooker, Electric
Stove or Range, Electric or Gas
Trash Compactor, Electric
Woodburning Stove/Heater
(P-8) Bought in Last 12 Months/For
Whom/Amount Spent
Hair Curler Set, Electric
Hair Dryer, Bonnet-Type or
Electric Hand-Held
Hair Styling Comb, Electric
Hot Lather Machine
Lighted Makeup Mirror
Shaver, Battery or Electric
Toothbrush, Electric
(P-8) Bought in Last 12
Months/Decision Maker
Drill, Electric
Electric Router
Garden Tiller
Hand Tool Outfit
Portable Workbench
Power Mower, Electric or Gas
Power Yard Trimmer
Sander, Electric
Saw:
Chain, Electric or Gas
Circular
Jig/Sabre
Stationary Radial/Arm
Snow Blower
Tractor, Garden
150
-------
Table 31. (Continued)
Product Category
Volume
Product
AT HOME SHOPPING,
YELLOW PAGES, FLORISTS
& TELEGRAMS: (P-12)
Hail & Phone Order (P-12)
Door-to-Door Sales
Florists
Telegrams & Wires
Auto Accessories
Recipe Cards
Cook Books
Books from Book Club
Other Books
Cosmetics
Records
Prerecorded Audio Cassette
Tapes
Prerecorded Audio Tape
Cartridges
Blank Audio Tapes or Cassettes
Magazines
Photo Processing
Fruit, Cheese or Specialty
Foods
Shoes or Boots
Clothing
Needlecraft Kits & Supplies
Camping Equipment
Sporting Goods (Such as
Fishing Tackle, Golf Balls,
Ski Poles, etc.)
Tools
Coins (Numismatic)
Medallions, Commemorative
Plates (Such as Commemorative
Medals, Ingots, Porcelain,
etc.)
Cookware & Kitchen Accessories
Small Appliances
Investment Information
Insurance
Real Estate Information
Educational Programs
Trees, Plants, Seeds
Tupperware Parties
Vitamins
151
-------
Table 31. (Continued)
Product Category
Volume
Product
AUTOMOBILES
AUTOMOTIVE PRODUCTS &
SERVICES
(P-l) Air Conditioning
Annual Miles Driven
Automobile Club
Bought New/Used
Burglar Alarm in Car
Car Leasing
Car Rentals
Current Auto Ownership
Current Driver's License
Decision Makers for One or
More Cars
How Purchased
Where Purchased
Insurance
Makes & Models of Cars
Owned/Domestic, Imported
Model Type/Size
Model Year Owned
Next Car Purchase
Radio/Tape Player
Type of Car (Body Style)
Type of Drive & Diesel Engine
When Acquired
(P-3) Air Filters
Antifreeze
Brake Linings/Pads
Car Batteries
Car Wax & Polish
Gasoline & Diesel Fuel
Gasoline Additives
Motor Oil
Motor Oil Additives
Mufflers
Oil Filters
Rustproofi ng
Shock Absorbers
Spark Plugs
Transmission Services
152
-------
Table 31. (Continued)
Product Category
Volume
Product
BANKING, INVESTMENTS,
MEMBERSHIPS, PUBLIC
ACTIVITIES & CONTRIBUTIONS
BEAUTY AIDS,
BEAUTY SALONS,
COSMETICS & PERSONAL
PRODUCTS - WOMEN
(P-5) Accounting Services
Auto Loans
Brokerage Account
Checking Accounts
Farm Ownership
Gold/Silver
I.R.A. or Keogh Plan
Memberships
Mortgages
Now Accounts
Personal Loans
Public Activities
Contributions to Public TV
Retirement & Investment
Property
Safe Deposit Boxes
Savings Accounts
Savings Certificates
Securities
Treasury Bills
Trust Agreements
Vacation/Weekend Homes
(P-28) Bath & Shower Additives
Beauty Salons
Blusher
Cotton Balls or Squares
Eye Liner
Eye Shadow
Face Powder/Loose, Pressed
Facial Moisturizers, Cleansing
Creams & Lotions
Feminine Hygiene Douches,
Suppositories & Spray
Deoderants
153
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-------
Table 31. (Continued)
Product Category
Volume
Product
DISTILLED SPIRITS & MIXES (P-16)
Alcoholic Beverages
Blended Whiskey or Rye
Bourbon Whiskey
Brand Influence of What Served
in Home
Brandy & Cognac
Canadian Whiskey
Cordials & Liqueurs
Gin
Irish Whiskey
Prepared Cocktail
Mixes with Liquor
Purchase Distilled Spirits by
the Case
Rum
Scotch Whiskey
Tequila
Vodka
FLOWER, VEGETABLE,
LAWN SEED & FERTILIZER
GAMES & TOYS
(P-8) Bought in Last 12
Months/Amount Spent
Fertilizers
House Plant Food, Lawn
Vegetable Garden, Other
Seed
Flower, Lawn, Vegetable
(P-29) Bought in Last 12
Months/Amount Spent
Video & Non-Video Electronic
Games
158
-------
Table 31. (Continued)
Product Category
Volume
Product
HAIR CARE PRODUCTS
HEALTH CARE PRODUCTS
& REMEDIES
(P-27) Creme Hair Rinses
Hair Coloring Products
Hair Conditioners
Hair Sprays
Hair Tonics or Dressings
Home Permanents
Shampoos
(P-25) Adhesive Bandages
Asthma Relief Remedies
Athlete's Foot Remedies
Cold, Allergy & Sinus Remedies
Cough Drops & Syrup
Diet Control Products
Eyeglasses & Contact Lenses
Headache Remedies & Pain
Relievers
Illnesses & Ailments
Indigestion Aids & Upset
Stomach Remedies
Laxatives
Medicated Throat Lozenges
Nasal Sprays
Pain Relieving Rubs & Liquids
Suntan & Sunscreen Products
Throat Lozenges/Medicated
Vitamins
HOME FURNISHINGS &
HOME IMPROVEMENTS
(P-9) Clocks: Wall, Mantle, Desk
Standing
Dinner & Tableware
Glassware
Crystalware
Fine China
Flatware
Other Dinnerware
Fluorescent & Incandescent
Lighting
Home Furnishings & Household
Durables
159
-------
Table 31. (Continued)
Product Category
Volume
Product
HOME FURNISHINGS &
HOME IMPROVEMENTS (conf) (P-9)
Beds/Other Bedroom Furniture
Blankets, Electric/Other
Comforters/Quilts
Curtains & Draperies
Dining Room Furniture
Mattresses
Pianos & Organs
Telephones & Telephone
Answering Machines
Pillowcases
Sheets
Towels
Home Improvements
Bathroom Plumbing
Carpeting
Fixtures
Flooring
Flue Dampers
Fireplaces
Furnace
Garage Door Opener
Hot Tubs/Whirlpools
Hot Water Heater
House Plans Purchase
Insulation for Ceiling, Floor
or Wall
Kitchen Cabinets & Sinks
Outdoor & Indoor Lighting
Outdoor Deck/Porch/Patio
Roofi ng
Siding
Storm Doors or Windows
Solar Heating/Solar Hot Water
Thermostats
Wall Paneling
Wallpaper
Weather Stripping
Interior & Exterior Remodeling
Paints & Stains
Exterior
Interior
160
-------
Table 31. (Continued)
Product Category
Volume
Product
HOUSEHOLD CLEANERS & ROOM
DEODORIZERS (P-24)
INSURANCE & CREDIT CARDS
(P-6)
JEWELRY, BINOCULARS,
WRISTWATCHES, PENS &
MECHANICAL PENCILS
(P-13)
Air Fresheners & Deodorizers
AlIfPurpose Cleaners
Bug Traps
Drain Cleaners
Floor Waxes
Furniture Polishes
Glue & Bonding Agents
Insecticides
Oven Cleaners
Rug Cleaners & Shampoos
Rug Deodorizers & Fresheners
Scouring Pads & Sponges
Scouring Powders
Termite & Rodent Control
Toilet Bowl Cleaners
Window & Glass Cleaners
Credit Cards
18 Credit Type Listings
How Billed or Printed
Used in Last 30 Days
Home Owners/Personal Property
Insurance
Life Insurance
Medical, Hospital, Health
Insurance
Other Types
Jewelry
Costume
Diamond
Gold
Other Jewelry and Gems
Pens & Mechanical Pencils
Bought for Self or Someone Else
Wristwatches/Men
Wri stwatches/Women
161
-------
Table 31. (Continued)
Product Category
Volume
Product
LUGGAGE
HALT BEVERAGES & WINES
(P-13) Luggage or Baggage
(P-17) Alcoholic Beverages
Ale
Beer
Domestic Light/Low-Calorie
Domestic Regular
Draft
Imported
Malt Liquor
Wine
Aperitif & Specialty
Champagne, Cold Duck &
Sparkling Wines
Light Domestic Dinner/Table
Domestic Dinner/Table
Imported Dinner/Table
Port, Sherry & Dessert
Sangri a/Pop/Party
Vermouth
MOTORCYCLES, SCOOTERS,
MINICYCLES & BIKES,
NOPEDS & MOPEDS
(P-2) Minicycles, Minibikes, Mopeds,
Nopeds, Motorscooters
Any Owned in Household
Decision Maker for Make
Bought - Type Owned
Most Recent Bought, New/Used
Type Owned by Household
Motorcycles
Bought New/Used
Decision Maker for One or More
Motorcycles
Engine Size
Motorcycles Owned in Household
Number Owned by Household
Members
Type Owned
162
-------
Table 31. (Continued)
Product Category
Volume
Product
ORAL HYGIENE PRODUCTS,
SKIN CARE & DEODORANTS
PET FOODS, FLEA &
TICK CARE PRODUCTS
(P-26) Breath Fresheners
Denture Cleansers
Deodorants & Antiperspirants
Hand & Body Creams, Lotions, or
Oils
Medicated Skin Care Products
Mouthwash
Toothbrushes
Toothpaste
(P-24) Cat Ownership
Cat Food
Canned
Packaged Dry
Packaged Hoist
Dog Ownership
Dog Food & Mixing Dog Food
Types
Canned
Packaged Dry
Packaged Moist
Flea & Tick Care Products for
Dogs & Cats
Decision Makers for Brands of
Dog & Cat Food (7 Different
Types)
163
-------
Table 31. (Continued)
Product Category
Volume
Product
PHOTOGRAPHY
RESTAURANTS, STORES &
GROCERY SHOPPING
SEWING
SHAVING PRODUCTS
(P-15) Cameras/Movie, Still
Film & Flash Equipment
Film Processing
Projectors, Movie, Slide
(P-11) Cents-Off-Coupons
Catalogue Showroom, Department
A Discount Stores
Shopped in Last 3
Months/Amounts Spent in Last
30 Days
Fast Food/Drive-in
Family & Steak House
Restaurants
Gourmet & Health Food
Specialty Stores
Grocery Shopping Expenditures
Supermarket & Food Shopping
Supermarkets & Convenience
Stores
(P-8) Finished Garments in Last 12
Months
General Sewing or Mending in
Last 12 Months
Sewing Materials & Notions
Sewing Patterns/Brands
Sewing Offers from Magazines
(P-27) After Shave Lotion & Cologne,
Use & Gift Purchases
Depilatories
Pre-Electric Shave Lotion
Razor Blades
Shavers/Disposable, Electric &
Battery
Shaving Cream or Gel
164
-------
Table 31. (Continued)
Product Category
Volume
Product
SOAP, LAUNDRY & PAPER
PRODUCTS/KITCHEN WRAPS
SOUP, HEAT, FISH, POULTRY,
CONDIMENTS & DRESSINGS
(P-23) Aluminum Foil
Automatic Dishwashing Detergent
Bleach
Dishwashing Liquid
Disposable Cups & Dispenser
Fabric Softeners
Facial Tissues
Laundry Pre-Soaks &
Pre-Cleaners
Laundry Washloads
Liquid Toilet Soaps
Paper Plates
Paper Towels
Plastic Garbage Bags & Trash
Liners
Plastic Sandwich or Food Bags
Plastic Type Kitchen Wraps
Reusable "Cloth" Towels
(Non-Woven)
Soaps & Detergents
Toilet Paper
Toilet Soap
(P-21) Bacon
Barbecue & Seasoning Sauces
Beef
Bouillon Cubes
Canned Chicken
Canned Heat Spreads
Canned Soup
Canned Tuna
Catsup
Coating & Stuffing Products
Cold Cuts
Cooking Spray
Corn Syrup
Corned Beef
165
-------
Table 31. (Continued)
Product Category
Volume
Product
SOUP, MEAT, FISH, POULTRY,
CONDIMENTS &
DRESSINGS (cont1)
(P-21) Corned Beef Hash
Deviled Ham
Dry Soup/Lunch Mix
Cornish Game Hen (Fresh/Frozen)
Frankfurters: Beef, Chicken &
Turkey
Fresh Fish/Shell Fish
Fresh Breast of Turkey
Other Fresh Turkey
Frozen Dinners & Courses
Frozen Fish/Shell Fish
Frozen Prepared Seafood
Fresh Chicken
Frozen Breast of Turkey
Frozen Pre-Stuffed Turkey
Other Frozen Whole Turkey
Frozen Fried Chicken
Other Frozen Chicken
Honey & Fructose
Mayonnai se
Mustard
Meat Tenderizer
Lamb
Pancake & Table Syrup
Pork
Pork Sausage
Salad & Cooking Oil
Salad Dressings
Sugar
Veal
Vienna Sausage
Stews
Canned Ham
Roast Beef Hash
166
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-------
Table 31. (Continued)
Product Category Volume Product
TRUCKS, VANS & SPORT/
UTILITY VEHICLES (P-2) Any Owned in Household
Bought to Replace Car/Truck
Decision Maker for Hake Bought
- Type Owned
Most Recent Bought New/Used by
Type
Model Year for Types Owned
Most Recent Bought
By 4-Wheel Drive & Diesel
Engi ne
By Type
Primary Purpose Used for
169
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170
-------
APPENDIX C
An Alphabetical Listing of Variables Used
1n This Volume
171
-------
Table 32. An Alphabetical Listing of Variables Used in this Volume
Variable
Definition
Units
ADD Annual.dermal dose mass/year
ADF Amount of product or residue deposited on fabric surface mass/area
AR Rate of application of film or coating to surface area/time
AV Area of skin surface exposed area
C Concentration of chemical substance in air at any point mass/volume
in time during exposure
CA^ Concentration of air at liquid/gas film interface moles/volume
CB] Concentration of chemical substance at liquid/gas moles/volume
film interface
Co Initial concentration of chemical substance in air mass/volume
as a result of an instantaneous release
WCS Concentration difference of chemical substance mass/volume
across specified tissue
Cso Initial concentration of migrant in polymer mass/volume
Cta Concentration of the chemical substance at the time mass/volume
at the end of application of film or coating
Ctg Concentration of the chemical substance at the time mass/volume
at the end of its continuous release
Ctr Concentration of the chemical substance at the time mass/volume
at the end of release of all substance from the
coating
D Diffusion coefficient of migrant through polymer mass
DA Dust adherence to skin mass/area
DAB Diffusion coefficient of chemical substance in air at area/time
25°C and 1 atmosphere
172
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Table 32. (continued)
Variable
DEX
OIL
DSY
OU
°W
F
FA
FA
FQ
G
QN
GNAR
IHX
IHXG
IHXp
ING
IR
Js
k
Definition
Annual dermal exposure
Dilution fraction
Density of product
Duration of exposure to consumer product
Diffusion coefficient in water
Fraction of migrant released from polymer
Fraction of spilled material entrained in air
Fraction of chemical substance absorbed
Frequency of exposure on an annual basis
Rate of release of chemical substance from consumer
product
Mass flux of chemical substance
Time-dependent release rate
Annual inhalation exposure
Annual exposure to inhaled particulates that enter
the gastrointestinal tract
Annual exposure to inhaled particulates that enter the
pulmonary region
Annual ingest ion exposure
Inhalation rate
Permeation rate (flux) of chemical substance
A constant that is a product of the mixing factor, m,
Units
mass/year
unitless
mass/ volume
time
area/time
unitless
unitless
unitless
unitless
mass/time
mass/area-time
mass/time^
mass/ year
mass/year
mass/year
mass/year
volume/time
mass/area-time
unitless
and the air exchange rate, Q/V
173
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Table 32. (continued)
Variable
Definition
Units
Kp Permeability constant
L Thickness of gas film or polymer
LR Leaching rate of chemical substance from object placed
in mouth to saliva
LUS Fraction of liquid used in the mouth that is swallowed
unintentionally
M Mass of consumer product spilled, sprayed, applied, or
used in any other manner
m Mixing factor
MA Molecular weight of air
MB Molecular weight of chemical substance
Mt Mass of migrant released from polymer
MW Molecular weight of chemical substance
N Molar flux of pure chemical substance
NRF Nonrespirable fraction (e.g., weight fraction of all
inhaled particles deposited in the head or
tracheobronchial region)
0V Fraction of product that is overspray (e.g., does not
contact intended surface)
P Vapor pressure of chemical substance at 25°C
PA^ Partial pressure of air at interface of liquid and
main air stream
PA2 Partial pressure of air at interface of gas film and
main air stream
volume/area-time
length
mass/time/area
unitless
mass
unitless
dimensionless
dimensionless
mass
dimensionless
moles/area-time
unitless
unitless
atmospheres
atmospheres
atmospheres
174
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Table 32. (continued)
Variable
Definition
Units
PB2
POE
Q
R
RF
SA
SAO
T
T
ta
TOE
TDF
te
TF
Partial pressure of chemical substance at interface
of liquid and main air stream
Partial pressure of chemical substances at interface
of gas film and main air stream
Fraction of inhaled particles subject to pulmonary
deposition
Ventilation air flow rate
Universal gas constant
Respirable fraction (e.g., weight fraction of all
inhaled particles deposited in the pulmonary air
space
Surface area covered by film or coating
Surface area of object being place in mouth
Film thickness of liquid on skin surface
Temperature
Time at the end of application
Fraction of inhaled particles deposited in the
respiratory tract
Total deposition fraction (e.g., weight fraction of
inhaled particles deposited in the respiratory tract)
Time at the end of exposure
Fraction of residue/dye transferred to the skin per
exposure event
Time at the end of release of chemical substance
atmospheres
atmospheres
unitless
volume/time
atm-cm3/mole-°K
unitless
area
area
length
degrees
time
unitless
unitless
time
unitless
time
175
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Table 32. (continued)
Variable Definition Units
to Time at the beginning of exposure time
tr Time at the end of release of all volatile chemical time
substance from a film or coating applied to a
surface
V Room volume volume
VA Molar volume of air volume/mole
V[J Molar volume of chemical substance at its normal volume/mole
boiling point
Vs Volume of polymer volume
WF Weight fraction of chemical substance in consumer unitless
product
WV Workspace volume volume
176
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APPENDIX D
Average Body Weights of Humans by Age Group
177
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Table 33. Average Body Weights of Humans by Age Group3
Age Group Body Weight
(kilograms)
Adults, age 18-74 71.8
Adult males, age 18-74 78.1
Adult females, age 18-74 65.4
Child-bearing females, age 18-44 64.0
Child, less than 3 years old 11.6
Child, age 3-6 17.4
Child, age 6-9 25.0
Child, age 9-12 36.0
Child, age 12-15 50.6
Child, age 15-18 61.2
a
Average values adapted from Anderson et al. (1984).
178
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APPENDIX E
Derivation of Equations for Estimating
Concentrations of Chemical Substances
in Indoor Air
179
-------
APPENDIX E
The derivation of equations for estimating concentrations of chemical
substances in indoor air at any point in time, t, as a result of a
time-dependent release are presented for four intervals. These are:
(1 ) 0 < t < t1 ;
(2) ^ < t < t2;
(3) t2 < t < tr; and
(4) t > tr.
The parameters, t] and t2, can represent the time to apply the liquid
film to a surface from which a chemical substance volatilizes (ta) or
the time required for a chemical substance to evaporate from a liquid
film once it has been applied to a surface (tg). If ta is smaller
than tg, then ti equals ta and t2 equals tg. If tg is
smaller than ta, then t-] equals tg and
parameter, tr, 1s the sum of t] and t?.
(1) For t < ti
g. g
equals ta
The
The mass balance equation and the physical interpretation of each
group of terms is
v = GNAR t - mqc.
(E-l)
{The net mass of \ (The mass of chemical) (The mass of chemical
chemical substance j. = < substance released >-< substance removed by
in air 1n the room) (to air in the room ) (air leaving the room
Upon dividing Equation (E-l) by V, Equation (E-l) becomes
dt
By letting
(E-2)
- mQ and k? -
V V
180
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and substituting k] and k2 as appropriate into Equation (E-2), the
resulting expression is
kiC. (E-3)
By letting
z = k2t - k^, (E-4)
and by differentiating with respect to time, the resulting expression is
(E-5)
By rearranging Equation (E-5), Equation (E-6) is
dC -1 /dz .
When Equation (E-6) and Equation (E-4) are substituted into Equation
(E-3), the resulting expression is
When Equation (E-7) is multiplied by k] and rearranged, the resulting
expression is
jjf = -kiz + k2. (E-8)
Equation (E-8) can be rearranged to
dz
= dt. (E-9)
Multiplying Equation (E-9) by k2 yields
When Equation (E-10) is integrated, the resulting expression is
-kp / ki \
__£ In 1 - z = k2t + C*. (E-ll)
k] \ k2 '
181
-------
When C = 0 at t = 0, this implies that z = 0 at t = 0 and that C* = 0.
Setting C* = 0 and dividing Equation (E-ll) by (-k2/k]) yields
In | 1 - !lL z | = -k-)t. (E-12)
Taking the antilog of Equation (E-12) yields
(E-13)
Substituting the expression from Equation (E-4) for z Into Equation
(E-13) and rearranging yields
By solving for C, the resulting expression is
C = -1 k
M- k2t]
/ J
which, upon rearranging, Is
C =
1 - e'^1- - t
Substituting GNAR/V for k2 yields
c .
(E-14)
(E-15)
(E-16)
(E-17)
The Equation to calculate the average concentration for any interval of
time where the time at the end of exposure is less than or equal to t-\
is obtained by integrating Equation (E-17) with respect to time and
dividing the resulting equation by the length of the exposure interval.
The resulting expression is
-ave -
GNAR
klV(tb - te)
> _ t _ e^l*"
2 k]
2
It =
-It = t,
(E-18)
182
-------
where
tjj = time at the beginning of the desired time Interval
te =' time at the end of the desired time interval.
(2) For t-| < t < t2
The mass balance equation and the physical Interpretation of each
group of terms Is
V jj£ = GNARt! - mQC. (E-19)
(The net mass of \ (The mass of chemical ) (The mass of chemical
-------
Solving for C by dividing by -k2/k-| yields
"1
Inll - j C 1= -kit + C*. (E-25)
V 2 /
Taking the antilog of Equation (E-25) yields
ki -kit
1 - £- C = C* e . (E-26)
To determine C*, substitute the expression for C in Equation (E-17) for
the parameter, C, in Equation (E-26). Substitute ti for the parameter,
t, in Equation (E-17). The resulting expression after these
substitutions are made is
K! GNAR/ 1 «
1 - td-TTwlti - r- + -TT Jl= C*e . (E-27)
GflAR/k-|V 1n Equation (E-27) can be simplified If one multiplies by
t-|/t-|. The parameter k2 can be substituted for
after which Equation (E-28) Is obtained:
Equation (E-28) can be simplified to Equation (E-29) by cancelling like
terms:
(E-29)
Multiplying Equation (E-29) by e ^ 1 and cancelling like terms yields
kltl - --- - e. . ) = C*. (E-30)
kit] /
Equation (E-30) can be further simplified to Equation (E-31).
184
-------
or
C* =
kit]
(E-32)
Substituting the expression for C* 1n Equation (E-32) for C* 1n Equation
(E-26) yields
C =
-k2
LL
[kit-
e - 1 e
kijkiti
Multiplying Equation (E-33) by -1 and rearranging yields
k2
C = 7-
- e
Substituting
for k2 in Equation (E-34) yields
or
k-|V
- r~\e
- e
")
Simplifying Equation (E-36) yields
C =
GNAR
Rearranging Equation (E-37) yields
GNAR I" e
C = T7w ti - -
"1
(E-33)
(E-34)
(E-35)
(E-36)
(E-37)
(E-38)
The equation to calculate the average concentration for any Interval of
time less where te Is less than or equal to t2 and t^ Is greater
than or equal to t] Is obtained by Integrating Equation (E-38) with
respect to time and dividing the resulting equation by the length of the
exposure Interval. The resulting expression Is
185
-------
Cave
(3) For t2 < t < tr
MR
MV(te-tb)
tit
t=t<
t=tb
(E-39)
The mass balance equation and the physical Interpretation of each
group of terms Is
j «
V = GNAR (tr-t) - mQC.
(E-40)
(The net mass of
jchemlcal substance
(in air In the room
The mass of chemical
substance released
to air 1n the room
The mass of chemical
- ^ substance removed by
air leaving the room
Dividing Equation (E-40) by V yields
dC
mQ
By letting
dt
mQ
k] = - and
(E-41)
and by substituting k-j and k2, as appropriate, into Equation (E-41),
one obtains
dC.
dt
= k2(tr-t) - kiC.
(E-42)
If we let
z = k2(tr-t) - k^ (E-43)
and differentiate with respect to time, the resulting expression is
dt = ~k2 ' kl df
Upon being rearranged, Equation (E-44) becomes
dC
dt"
(E-44)
(E-45)
186
-------
If Equations (E-43) and (E-45) are substituted into Equation (E-42), the
resulting expression is
= z. (E-46)
Multiplying Equation (E-46) by -k-| yields
jjf + k2 = -kiz. (E-47)
Rearranging Equation (E-47) yields
|jf = -(k2 + kiz). (E-48)
Rearranging Equation (E-48) yields
k2 +d^z = -dt. (E-49)
Integrating Equation (E-49) with respect to
£- In (k2 + kiz) = -t * B". (E-50)
Multiplying Equation (E-50) by ki yields
In (k2 + kiz) = -kit * B1. (E-51)
If one takes the antilog of Equation (E-51), the resulting expression is
k2 + kiz = Be"klt. (E-52)
To determine B in Equation (E-52), substitute the expression for z from
Equation (E-43) in Equation (E-52). When t equals t2, C is equal to
Ct2. Therefore, substitute t2 for t and Ct2 for C to determine B.
Ct2 is calculated by substituting t2 for t in Equation (E-37). The
resulting expressing is
k2 + k-) k2 (tr-t2) - kiCt2 = Be~. (E-53)
Rearranging Equation (E-53) yields
=
187
-------
6 =
k-,k2 (tr-t2) - h2 Ct2].
(E-54)
Substituting the expression for z from Equation (E-43) into Equation
(E-52) yields
k2 + k!k2 <2 (tr-t)]. (E-58)
Simplifying Equation (E-58) results in
-k-|2C = e(~klt + klt2)rk2 + k!k2 (tr-t2) - k2 Ct2l
-[k2 + k-,k2 (tr-t)]. (E-59)
Simplifying Equation (E-59) results in
. -k-,(t-t2)r . -I
-k-]2c = e ' I k2 + k-|k2 (tr-t2) - k12ct2J
-Tk2 * k]k2 (tr-t)l. (E-60)
Dividing Equation (E-60) by -k-)2 yields
:t-t2)
C = e
- ?- (tr-t2) + ct2
^1 k]
Kl
(tr-t)
(E-61)
188
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Substituting
for k2 in Equation (E-61) and rearranging yields
-kl(t-t2)
-e
GNAR GNAR
:tr-t2) -
GNAR GNAR
!E-62)
Is calculated using Equation (E-38) by setting t equal to t2. The
equation to calculate the average concentration for any interval of time where
te is less than or equal to tr and t^ is greater than or equal to t2
is derived by integrating Equation (E-62) with respect to time and dividing
the resulting equation by the length of the exposure interval. The resulting
expression is
1
ave -
GNAR
k-|2v
(te-tb)
GNAR
k]V
-Mt-t2)
e
tr-| >
t=t
t=t
GNAR
e
b
+ TT (tr-t2) - Ct2
(E-63)
(4) For t > tr
Equation (3-7) with Ctr substituted for C0 and with (t-tr)
substituted for t is used to calculate the concentration at any time after
tr. Ctr is calculated by substituting tr for t in Equation (E-62). As
the time during this Interval increases, the concentration decreases
exponentially as air containing the chemical flows out of the room.
C = Ct
Je-m(Q/V)(t-trj]
(E-64)
The equation to calculate the average concentration for any interval of time
where te and tb are greater than or equal to tr is derived by
integrating Equation (E-64) with respect to time. The resulting expression is
Cave =
f -k(t-tr)]t=te
r~**~H
L Jt=tb
(E-65)
189
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