United States September 2006 

Environmental Protection External Review Draft 

Agency EPA/600/R/06/096A 

Child-Specific 

Exposure Factors 

Handbook (External 

Review Draft) 
DISCLAIMER 

This document is a draft edition that has not been fully reviewed by EPA. Mention of 

trade names or commercial products does not constitute endorsement or recommendation for use. 

i 
TABLE OF CONTENTS

1. INTRODUCTION ........................................................ 1-1

1.1 BACKGROUND ................................................ 1-1

1.2 PURPOSE ..................................................... 1-4

1.3 INTENDED AUDIENCE ......................................... 1-5

1.4 SELECTION OF STUDIES FOR THE HANDBOOK ................... 1-5

1.5 APPROACH USED TO DEVELOP RECOMMENDATIONS FOR EXPOSURE

FACTORS ..................................................... 1-8

1.6 CHARACTERIZING VARIABILITY .............................. 1-11

1.7 USING THE HANDBOOK IN AN EXPOSURE ASSESSMENT ......... 1-12

1.8 THE USE OF AGE GROUPINGS WHEN ASSESSING EXPOSURE ..... 1-14

1.9 CONSIDERING LIFESTAGE WHEN CALCULATING EXPOSURE AND RISK

............................................................. 1-16

1.10 GENERAL EQUATIONS FOR CALCULATING DOSE ............... 1-17

1.11 CUMULATIVE RISK ........................................... 1-22

1.12 RESEARCH NEEDS ............................................ 1-22

1.13 ORGANIZATION .............................................. 1-23

1.14 REFERENCES FOR CHAPTER 1 ................................. 1-25

2. BREAST MILK INTAKE .................................................. 2-1

2.1 INTRODUCTION ............................................... 2-1

2.2 STUDIES ON BREAST MILK INTAKE ............................. 2-2

2.2.1 Pao et al., 1980 ............................................ 2-2

2.2.2 Dewey and Lönnerdal, 1983 ................................. 2-2

2.2.3. Butte et al., 1984 .......................................... 2-3

2.2.4. Neville et al., 1988 ......................................... 2-4

2.2.5. Dewey et al., 1991a, b ...................................... 2-4

2.3 STUDIES ON LIPID CONTENT AND FAT INTAKE FROM BREAST MILK

.............................................................. 2-5

2.4 OTHER FACTORS .............................................. 2-7

2.4.1. Population of Nursing Infants ................................ 2-7

2.4.2. Intake Rates Based on Nutritional Status ....................... 2-8

2.5 RECOMMENDATIONS .......................................... 2-9

2.5.1 Breast Milk Intake ........................................ 2-9

2.5.2 Lipid Content and Lipid Intake .............................. 2-10

2.6 REFERENCES FOR CHAPTER 2 ................................. 2-11

3. FOOD INTAKE .......................................................... 3-1

3.1 INTRODUCTION ............................................... 3-1

3.2 INTAKE RATE DISTRIBUTIONS FOR VARIOUS FOOD TYPES ....... 3-4

3.2.1 USDA, 1999 .............................................. 3-4

3.2.2 U.S. EPA, 2003 ........................................... 3-6

ii 
3.3 FISH INTAKE RATES ........................................... 3-9

3.3.1 General Population Studies .................................. 3-9

3.3.1.1. U.S. EPA, 2002 .................................... 3-9

3.3.1.2. Tsang and Klepeis, 1996 ............................ 3-10

3.3.2 Freshwater Recreational Study .............................. 3-11

3.3.3 Native American Subsistence Studies ......................... 3-13

3.3.3.1 Columbia River Inter-Tribal Fish Commission (CRITFC), 1994

................................................. 3-13

3.3.3.2. Toy et al., 1996 ................................... 3-15

3.3.3.3. The Suquamish Tribe, 2000 .......................... 3-16

3.3.4 Multi-State Study ......................................... 3-17

3.4 FAT INTAKE ................................................. 3-18

3.4.1. Bogalusa Heart Study ..................................... 3-18

3.4.2. U.S. EPA 2006 ........................................... 3-19

3.5 TOTAL DIETARY INTAKE AND CONTRIBUTIONS TO DIETARY INTAKE

............................................................. 3-19

3.6 INTAKE OF HOME-PRODUCED FOODS .......................... 3-22

3.7 SERVING SIZE STUDY BASED ON THE USDA NFCS .............. 3-27

3.8 CONVERSION BETWEEN “AS CONSUMED” AND DRY WEIGHT INTAKE

RATES ....................................................... 3-28

3.9 FAT CONTENT OF MEAT AND DAIRY PRODUCTS ................ 3-29

3.10 RECOMMENDATIONS ......................................... 3-30

3.11 REFERENCES FOR CHAPTER 3 ................................. 3-32

APPENDIX 3A Calculations Used in the 1994-96 CSFII Analysis to Correct for Mixtures 

CSFII Data 

NFCS Data 

APPENDIX 3B Food Codes and Definitions Used in Analysis of the 1994-96 USDA 

APPENDIX 3C Sample Calculation of Mean Daily Fat Intake Based On CDC (1994) Data 

APPENDIX 3D Food Codes and Definitions Used in Analysis of the 1987-88 USDA 

APPENDIX 3E Statistical Notes 

4. DRINKING WATER INGESTION ........................................... 4-1

4.1 INTRODUCTION ............................................... 4-1

4.2 DRINKING WATER INGESTION STUDIES ......................... 4-2

4.2.1 U.S. EPA, 2004 ........................................... 4-2

4.2.2. EPA Analysis of CSFII (USDA, 1998) ......................... 4-3

4.3 RECOMMENDATIONS .......................................... 4-4

4.4 REFERENCES FOR CHAPTER 4 .................................. 4-6

5. SOIL INGESTION AND PICA .............................................. 5-1

5.1 INTRODUCTION ............................................... 5-1

5.2 SOIL INTAKE STUDIES ......................................... 5-3

5.2.1 Key Studies of Primary Analysis ............................. 5-3

iii 
5.2.1.1 Davis et al., 1990 ................................... 5-3

5.2.1.2 Calabrese et al., 1997a .............................. 5-5

5.2.1.3 Davis and Mirick, 2006 .............................. 5-7

5.2.2 Relevant Studies of Primary Analysis .......................... 5-8

5.2.2.1 Binder et al., 1986 .................................. 5-8

5.2.2.2 Clausing et al., 1987 ............................... 5-10

5.2.2.3 Calabrese et al., 1989 ............................... 5-11

5.2.2.4 Van Wïjnen et al., 1990 ............................. 5-13

5.2.2.5 Calabrese et al., 1996 ............................... 5-14

5.2.2.6 Calabrese et al., 1999 ............................... 5-15

5.2.2.7 Stanek and Calabrese, 2000 .......................... 5-15

5.2.2.8 Stanek et al., 2001b ............................... 5-15

5.2.3 Key Studies of Secondary Analysis ........................... 5-16

5.2.3.1 Stanek and Calabrese, 1995a ......................... 5-16

5.2.3.2 Stanek and Calabrese, 1995b ......................... 5-18

5.2.4 Relevant Studies of Secondary Analysis ....................... 5-19

5.2.4.1 Thompson and Burmaster, 1991 ...................... 5-19

5.2.4.2 Calabrese and Stanek, 1992a ......................... 5-20

5.2.4.3 Sedman and Mahmood , 1994 ........................ 5-21

5.2.4.4 Calabrese and Stanek, 1995 .......................... 5-22

5.2.4.5 Stanek et al., 2001a ................................ 5-23

5.2.4.6 Zartarian et al., 2005 ................................ 5-24

5.3 PICA ........................................................ 5-25

5.3.1 Prevalence .............................................. 5-25

5.3.1.1 General Pica ............................................. 5-25

5.3.1.2 Soil Pica ................................................ 5-25

5.3.2 Soil Pica Among Children .................................. 5-26

5.3.2.1 Calabrese et al., 1991 ............................... 5-26

5.3.2.2 Calabrese and Stanek, 1992b ......................... 5-27

5.3.2.3 Calabrese and Stanek, 1993 .......................... 5-27

5.3.2.4 Zartarian et al., 2005 ............................... 5-29

5.4 RECOMMENDATIONS ......................................... 5-29

5.5 REFERENCES FOR CHAPTER 5 ................................. 5-33

6. OTHER NON-DIETARY INGESTION FACTORS .............................. 6-1

6.1 INTRODUCTION ............................................... 6-1

6.2 STUDIES RELATED TO NON-DIETARY INGESTION ................ 6-2

6.2.1 Davis, 1995 .............................................. 6-2

6.2.2 Groot et al., 1998 .......................................... 6-5

6.2.3 Reed et al., 1999 .......................................... 6-6

6.2.4 Zartarian et al., 1997 and 1998 ............................... 6-7

6.2.5 Stanek et al., 1998 ......................................... 6-8

6.2.6 Freeman et al., 2001 ....................................... 6-10

6.2.7 Juberg et al., 2001 ........................................ 6-11

iv 
6.2.8 Greene, 2002 ............................................ 6-12

6.2.9 Tulve et al., 2002 ......................................... 6-13

6.2.10 Smith and Norris, 2003 .................................... 6-14

6.2.11 AuYeung et al., 2004 ..................................... 6-15

6.2.12 Black et al., 2005 ......................................... 6-16

6.3 RECOMMENDATIONS ......................................... 6-17

6.4 REFERENCES FOR CHAPTER 6 ................................. 6-19

7. INHALATION ROUTE .................................................... 7-1

7.1 INTRODUCTION ............................................... 7-1

7.2 INHALATION RATE STUDIES ................................... 7-1

7.2.1 Linn et al., 1992 .......................................... 7-1

7.2.2 Spier et al., 1992 .......................................... 7-2

7.2.3 Adams, 1993 ............................................. 7-4

7.2.4 Layton, 1993 ............................................. 7-5

7.2.5 Rusconi et al., 1994 ........................................ 7-7

7.2.6 Lordo et al., 2006 .......................................... 7-9

7.3 RECOMMENDATIONS ......................................... 7-11

7.4 REFERENCES FOR CHAPTER 7 ................................. 7-12

APPENDIX 7A: VENTILATION DATA .................................. 7-38

8. DERMAL ROUTE ........................................................ 8-1

8.1 INTRODUCTION ............................................... 8-1

8.2 SURFACE AREA ............................................... 8-2

8.2.1. Background .............................................. 8-2

8.2.2. Measurement Techniques ................................... 8-2

8.2.3. Body Surface Area Studies .................................. 8-3

8.2.3.1. Costeff, 1966 ...................................... 8-3

8.2.3.2. U.S. EPA, 1985 .................................... 8-4

8.2.3.3. Phillips et al., 1993 ................................ 8-5

8.2.3.4. Wong et al. (2000) ................................. 8-6

8.2.3.5. U.S. EPA Analysis of NHANES III Data ................ 8-6

8.2.4. Application of Body Surface Area Data ........................ 8-7

8.3 ADHERENCE OF SOLIDS TO SKIN ............................... 8-8

8.3.1. Background .............................................. 8-8

8.3.2. Adherence of Solids to Skin Studies ........................... 8-8

8.3.2.1. Kissel et al., 1996a ................................. 8-8

8.3.2.2. Kissel et al., 1996b ................................. 8-8

8.3.2.3. Holmes et al., 1999 ................................. 8-9

8.3.2.4. Kissel et al., 1998 ................................. 8-10

8.4 RECOMMENDATIONS ......................................... 8-12

8.4.1. Body Surface Area ........................................ 8-12

8.5 REFERENCES FOR CHAPTER 8 ................................. 8-15

v 
APPENDIX 8A - Formulas for Total Body Surface Area ..................... 8A-1

9. ACTIVITY FACTORS ..................................................... 9-1

9.1 INTRODUCTION ............................................... 9-1

9.2 ACTIVITY PATTERNS .......................................... 9-1

9.2.1 Timmer et al., 1985 ........................................ 9-2

9.2.2 Robinson and Thomas, 1991 ................................. 9-3

9.2.3 Wiley et al., 1991 .......................................... 9-4

9.2.4 U.S. EPA, 1992 and U.S. EPA, 2004 .......................... 9-5

9.2.5 Tsang and Klepeis, 1996 .................................... 9-5

9.2.6 Funk et al., 1998 .......................................... 9-9

9.2.7 Hubal et al., 2000 ........................................ 9-10

9.2.8 Wong et al., 2000 ......................................... 9-11

9.3 RECOMMENDATIONS ......................................... 9-13

............................................................. 9-13

10. CONSUMER PRODUCTS ............................................... 10-1

10.1 BACKGROUND ............................................... 10-1

10.2 CONSUMER PRODUCTS USE STUDIES .......................... 10-1

10.3 RECOMMENDATIONS ......................................... 10-2

10.4 REFERENCES FOR CHAPTER 10 ................................ 10-3

11. BODY WEIGHT STUDIES ............................................... 11-1

11.1 INTRODUCTION .............................................. 11-1

11.2 BODY WEIGHT STUDIES ...................................... 11-1

11.2.1 Hamill et al., 1979 ........................................ 11-1

11.2.2. National Center for Health Statistics, 1987 ..................... 11-1

11.2.3. Burmaster and Crouch, 1997 ................................ 11-2

11.2.4 U.S. EPA, 2000 .......................................... 11-3

11.2.5 Ogden et al., 2004 ........................................ 11-3

11.2.6 EPA Analysis of NHANES III Data .......................... 11-4

11.3 RECOMMENDATIONS ......................................... 11-5

11.4 REFERENCES FOR CHAPTER 11 ................................ 11-5

vi 
LIST OF TABLES

Table 1-1. Considerations Used to Rate Confidence in Recommended Values ........... 1-21

Table 1-2. Summary of Exposure Factor References and Confidence Ratings ........... 1-29

Table 1-3. Characterization of Variability in Exposure Factors ....................... 1-30

Table 1-4. Integrating EPA’s Guidance on Selecting Age Groups for Monitoring and Assessing

Childhood Exposures to Environmental Contaminants with EPA’s Supplemental 

Guidance for Assessing Susceptibility from Early-Life Exposure to Carcinogens For 

Those Contaminants Which Act Via a Mutagenic Mode of Action .............. 1-31

Table 2-1. Daily Intakes of Breast Milk ......................................... 2-12

Table 2-3. Breast Milk Intake among Exclusively Breast-fed Infants During the First 4 Months

Table 2-6. Lipid Content of Human Milk and Estimated Lipid Intake among Exclusively BreastTable 2-7. Percentage of Mothers Breast-feeding Newborn Infants in the Hospital and Infants at

5 or 6 Months Of Age in the United States in 1989 and 1995, by Ethnic Background and

Table 3-7. Milk and Milk Products: Mean Quantities consumed daily by sex and age, per capita

Table 3-11. Eggs, Legumes, Nuts and Seeds, Fats and Oils, Sugars and Sweets: Mean Quantities

Table 3-12. Eggs, Legumes, Nuts and Seeds, Fats and Oils, Sugars and Sweets: Percentage of

Table 2-2. Breast Milk ...................................................... 2-12

of Life .............................................................. 2-13

Table 2-4. Breast Milk Intake During a 24-hour Period ............................. 2-14

Table 2-5. Breast Milk Intake Estimated by the DARLING Study .................... 2-15

fed Infants .......................................................... 2-15

Selected Demographic Variables ......................................... 2-16

Table 2-8. Confidence in Breast Milk Intake Recommendations ...................... 2-17

Table 2-9. Breast Milk Intake Rates Derived from Key Studies ...................... 2-18

Table 2-10. Lipid Intake Rates Derived from Key Studies .......................... 2-19

Table 2-11. Summary of Recommended Breast Milk And Lipid Intake Rates ........... 2-20

Table 3-1. Grain Products: Mean Quantities consumed daily by sex and age, per capita .... 3-35

Table 3-2. Grain Products: Percentage of individuals consuming, by sex and age ......... 3-36

Table 3-3. Vegetables: Mean Quantities consumed daily by sex and age, per capita ....... 3-37

Table 3-4. Vegetables: Percentage of individuals consuming, by sex and age ............ 3-38

Table 3-5. Fruits: Mean Quantities consumed daily by sex and age .................... 3-39

Table 3-6. Fruits: Percentage of individuals consuming, by sex and age ................ 3-40

................................................................... 3-41

Table 3-8. Milk and Milk Products: Percentage of individuals consuming, by sex and age . . 3-42

Table 3-9. Meat, Poultry, and Fish: Mean Quantities consumed daily by sex and age ...... 3-43

Table 3-10. Meat, Poultry, and Fish: Percentage of individuals consuming, by sex and age . 3-44

consumed daily by sex and age .......................................... 3-45

individuals consuming, by sex and age .................................... 3-46

Table 3-13. Beverages: Mean Quantities consumed daily by sex and age ............... 3-47

Table 3-14. Beverages: Percentage of individuals consuming, by sex and age ........... 3-48

Table 3-15. Unweighted Number of Observations, 1994/96 CSFII Analysis ............ 3-49

Table 3-16. Per Capita Intake of the Major Food Groups (g/kg-day as consumed) ........ 3-50

vii 
Table 3-17. Per Capita Intake of Individual Foods (g/kg-day as consumed) ............. 3-52

Table 3-18. Per Capita Intake of USDA Categories of Vegetables and Fruits (g/kg-day as

Table 3-19. Per Capita Intake of Exposed/Protected Fruit and Vegetable Categories (g/kg-day as

Table 3-20. Per Capita Distribution of Fish (Finfish and Shellfish) Intake by Age and Gender ­

Table 3-21. Consumers Only Distribution of Fish (Finfish and Shellfish) Intake by Age and

Table 3-22. Per Capita Distribution of Fish (Finfish and Shellfish) Intake by Age and Gender ­

Table 3-23. Consumers Only Distribution of Fish (Finfish and Shellfish) Intake by Age and

Table 3-24. Number of Respondents Reporting Consumption of a Specified Number of Servings

Table 3-25. Mean Fish Intake Among Individuals Who Eat Fish and Reside in Households With

Table 3-26. Fish Consumption Rates among Native American Children (age 5 years and under)

Table 3-27. Mean, 50th, and 90th Percentiles of Consumption Rates for Native American

Table 3-28. Native American Children’s Consumption Rate (g/kg/day): Individual Finfish and

Table 3-29. Native American Children’s Consumption Rate (g/kg/day) for Consumers Only:

Table 3-30. Mean Fish Consumption, per capita, g/day and g/kg/day As Consumed, in Four

Table 3-31. Mean Fish Consumption, Consumers Only, g/day and g/kg/day As Consumed, in

Table 3-32. Mean Fish Consumption, Consumers Only, g/day and g/kg/day As Consumed, by

Table 3-36. Total Fat Intake for the Whole Population and for the Top 10% of Animal Fat Consumers

Table 3-40. Per Capita Intake of Total Foods and Major Food Groups, and Percent of Total

Food Intake for Individuals with Low-end, Mid-range, and High-end Total Food Intake

consumed) .......................................................... 3-56

consumed) .......................................................... 3-58

As Consumed ........................................................ 3-60

Gender - As Consumed ................................................ 3-61

Uncooked Fish Weight ................................................ 3-62

Gender - Uncooked Fish Weight ......................................... 3-63

of Seafood in 1 Month and Source of Seafood Eaten ......................... 3-64

Recreational Fish Consumption .......................................... 3-65

................................................................... 3-66

Children Age Birth to Five Years (g/kg/day) ............................... 3-67

Shellfish and Fish Groups .............................................. 3-68

Individual Finfish and Shellfish and Fish Groups ............................ 3-69

States .............................................................. 3-70

Four States .......................................................... 3-71

Caught or Bought Status ............................................... 3-72

Table 3-33. Fat Intake Among Children Based on Data from the Bogalusa Heart Study, 1973­

1982 (g/day) ......................................................... 3-73

Table 3-34. Fat Intake Among Children Based on Data from the Bogalusa Heart Study, 1973­

1982 (g/kg/day) ...................................................... 3-74

Table 3-35. Mean Total Daily Dietary Fat Intake (g/day) Grouped by Age and Gender .... 3-75

by Consumers Only (g/kg-day) ............................................ 3-76

Table 3-37. Per Capita Total Dietary Intake ...................................... 3-77

Table 3-38. Per Capita Intake of Major Food Groups (g/day, as consumed) ............. 3-78

Table 3-39. Per Capita Intake of Major Food Groups (g/kg/day, as consumed) .......... 3-82

viii 

3-85 
Table 3-41. Per Capita Intake of Total Foods and Major Food Groups, and Percent of Total 

Food Intake for Individuals with Low-end, Mid-range, and High-end Total Meat Intake3-88 

Table 3-42. Per Capita Intake of Total Foods and Major Food Groups, and Percent of Total

Food Intake for Individuals with Low-end, Mid-range, and High-end Total Meat and

Dairy Intake ......................................................... 3-91

Table 3-43. Per Capita Intake of Total Foods and Major Food Groups, and Percent of Total 

Food Intake for Individuals with Low-end, Mid-range, and High-end Total Fish Intake3-94 

Table 3-44. Per Capita Intake of Total Foods and Major Food Groups, and Percent of Total

Food Intake for Individuals with Low-end, Mid-range, and High-end Total Fruit and

Vegetable Intake ..................................................... 3-97

Table 3-45. Per Capita Intake of Total Foods and Major Food Groups, and Percent of Total 

Food Intake for Individuals with Low-end, Mid-range, and High-end Total Dairy Intake 3-100

Table 3-46. Weighted and Unweighted Number of Observations (Individuals) for NFCS Data

Used in Analysis ofFood Intake ......................................... 3-103

Table 3-47. Consumer Only Intake of Homegrown Foods (g/kg-day)a - All Regions Combined

.................................................................. 3-104

Table 3-48. Percent Weight Losses from Food Preparation ......................... 3-105

Table 3-49. Quantity (as consumed) of Food Groups Consumed Per Eating Occasion and the

Percentage of Individuals Using These Foods Over a Three-Day Period in a 1977-1978

Survey ............................................................ 3-106

Table 3-50. Mean Moisture Content of Selected Food Groups Expressed as Percentages of

Edible Portions ...................................................... 3-108

Table 3-51. Percent Moisture Content for Selected Fish Speciesa .................... 3-113

Table 3-52. Percentage Lipid Content (Expressed as Percentages of 100 Grams of Edible

Portions) of Selected Meat, Dairy, and Fish Productsa ....................... 3-116

Table 3-53. Fat Content of Meat Products ...................................... 3-120

Table 3-54. Summary of Recommended Values for Per Capita Intake of Foods, As Consumed

.................................................................. 3-121

Table 3-55. Confidence Intake Recommendations for Various Foods, Including Fish (General

Population) ......................................................... 3-123

Table 3-56. Confidence Intake Recommendations for Fish Consumption - Recreational

Freshwater Angler Population .......................................... 3-124

Table 3-57. Summary of Fish Intake Rates Among Native American Children (Consumers Only)

.................................................................. 3-125

Table 3-58. Confidence Intake Recommendations for Fish Consumption - Native American

Subsistence Population ............................................... 3-126

Table 3A-1. Fraction of Grain and Meat Mixture Intake Represented by Various Food

Items/groups ........................................................ 3A-2

Table 3B-1 Food Codes and Definitions Used in Analysis of the 1994-96 USDA CSFII Data

...................................................................3B-1

Table 3D-1. Food Codes and Definitions Used in Analysis of the 1987-88 USDA NFCS Data

.................................................................. 3D-1

Table 4-1. Estimated Direct and Indirect Water Ingestion for Selected Age Categories Derived

from CSFII Data ...................................................... 4-7

ix 
Table 4-2. Estimated Direct and Indirect Community Water Ingestion By Source for Entire U.S.

Population (All Ages)a .................................................. 4-8

Table 4-3. Estimated Direct and Indirect Water Ingestion, All Sources By Age Category for U.S.

Table 4-4. Estimated Direct and Indirect Community Water Ingestion By Age Category for U.S.

Table 4-5. Estimated Direct and Indirect Bottled Water Ingestion By Age Category for U.S.

Table 4-6 Estimated Direct and Indirect Other Water Ingestion By Age Category for U.S.

Table 5-1. Average Daily Soil Ingestion Values Based on Aluminum, Silicon, and Titanium as

Table 5-2. Soil Ingestion Estimates for the Median of Best Four Trace Elements Based on

Table 5-3. Dust Ingestion Estimates for the Median of Best Four Trace Elements Based on

Table 5-5. Estimated Daily Soil Ingestion Based on Aluminum, Silicon, and Titanium

Table 5-10. Geometric Mean (GM) and Standard Deviation (GSD) LTM Values for Children at

Table 5-11. Estimated Geometric Mean Ltm Values of Children Attending Daycare Centers

Table 5-13. Estimated Distribution of Individual Mean Daily Soil Ingestion Based on Data for

Table 5-14. Summary Statistics and Parameters for Distributions of Estimated Soil Ingestion by

Table 5-15. Positive/negative Error (Bias) in Soil Ingestion Estimates in the Calabrese et al.

Table 5-16. Daily Soil Ingestion Estimation in a Soil-Pica Child by Tracer and by Week

Children ............................................................. 4-9

Children ............................................................ 4-10

Children ............................................................ 4-11

Children ............................................................ 4-12

Table 4-7. Summary of Recommended Community Drinking Water Ingestion Rates ..... 4-13

Table 4-8. Confidence in Water Ingestion Recommendations ........................ 4-14

Tracer Elements ...................................................... 5-37

Food/Soil Ratios for 64 Anaconda Children (mg/day) Using Al, Si, Ti, Y, and Zr . . 5-37

Food/Dust Ratios for 64 Anaconda Children (mg/day) Using Al, Si, Ti, Y, and Zr . . 5-38

Table 5-4. Mean and Median Soil Ingestion (mg/day) by Family Member .............. 5-38

Concentrations ....................................................... 5-39

Table 5-6. Calculated Soil Ingestion by Nursery School Children .................... 5-40

Table 5-7. Calculated Soil Ingestion by Hospitalized, Bedridden Children .............. 5-41

Table 5-8. Mean and Standard Deviation Percentage Recovery of Eight Tracer Elements . . 5-41

Table 5-9. Soil and Dust Ingestion Estimates for Children Ages 1-4 Years ............. 5-42

Daycare Centers and Campgrounds ....................................... 5-43

According to Age, Weather Category, and Sampling Period ................... 5-44

Table 5-12. Distribution of Average (Mean) Daily Soil Ingestion Estimates per Child for 64

Children (mg/day) .................................................... 5-45

64 Subjects Projected over 365 Days ..................................... 5-45

Tracer Elementa ...................................................... 5-46

(1989) Mass-balance Study: Effect on Mean Soil Ingestion Estimate (mg/day) .... 5-47

(mg/day) ............................................................ 5-48

Table 5-17. Ratios of Soil, Dust, and Residual Fecal Samples in the Soil Pica Child ...... 5-49

................................................................... 5-50

Table 5-18. Daily Variation of Soil Ingestion by Children Displaying Soil Pica in Wong (1988)

Table 5-19 Key Studies Used to Derive Recommendations .......................... 5-51

x 
Table 5- 20 . Summary of Estimates of Incidental Soil and Dust Ingestion by Children (1-7 

years old) from Key Studies (mg/day) ............................... 5-52

Table 5-21. Summary of Recommended Values for Soil Ingestion .................... 5-53

Table 5-22. Confidence in Soil Intake Recommendation ............................ 5-54

Table 6-1. Extrapolated Total Mouthing Times Minutes per Day (time awake) .......... 6-21

Table 6-2. Frequency of Contact (Contacts per Hour) .............................. 6-22

Table 6-3. Prevalence of Non-Food Ingestion/Mouthing Behaviors by Child’s Age: Percent of

Children Whose Parents Reports the Behavior in the Past Month ............... 6-23

Table 6-4 Percent of Children with Reported Behaviors From the Telephone Survey Conducted

in the MNCPES (n = 168) .............................................. 6-26

Table 6-5. Median (Mean) Observed Activity Rate (Hand Contacts Per Hour) Based on 4 Hours

of Observation Per Person. ............................................. 6-26

Table 6-6. Comparison of Observed Activities for Boys and Girls (Mean). ............. 6-27

Table 6-7. Mouthing times for Pacifiers and Other Objects, by Age Category ........... 6-27

Table 6-8 . Average Mouthing Time by Object Category and Age (min/hr) ............. 6-28

Table 6-9. Mouthing Time Statistics for Various Objects (min/hr) .................... 6-29

Table 6-10. Estimated Daily Mouthing Times for Various Objects (min/day) ........... 6-31

Table 6-11. Variability in Objects Mouthed for Different Age Groups. ................ 6-32

Table 6-12. Mouthing Duration by Age Group for Pacifiers, Fingers, Toys, and 

Other Objects ........................................................ 6-33

Table 6-13. Indoor Mouthing Frequency (Contacts/Hour) ........................... 6-34

Table 6-14. Outdoor Mouthing Frequency (Contacts/Hour) ......................... 6-35

Table 6-15. Indoor Mouthing Contact Duration (Minutes/Hour) ...................... 6-36

Table 6-16. Outdoor Mouthing Contact Duration (Minutes/Hour) .................... 6-37

Table 6-17. Videotaped Mouthing and Food-handling Activity as Median Hourly Frequency

(Contacts/Hour) and Median Duration (% of Tape Time) (Mean ± SD) .......... 6-38

Table 6-18. Summary of Studies on Mouthing Behavior ............................ 6-39

Table 6-19. Summary of Mouthing Frequency Data ............................... 6-40

Table 6-20. Summary of Recommended Values for Total Mouthing Time

(minutes per day) ..................................................... 6-42

Table 6-21. Summary of Recommended Values for Mouthing Frequency 

(contacts per hour) .................................................... 6-43

Table 6-22. Confidence in Mouthing Behavior Recommendations .................... 6-44

Table 7-1. Calibration And Field Protocols For Self-monitoring of Activities Grouped by

Subject Panels ....................................................... 7-13

Table 7-2. Subject Panel Inhalation Rates by Mean VR, Upper Percentiles, And Self-estimated

Breathing Rates ...................................................... 7-13

Table 7-3. Distribution of Predicted Intake Rates by Location And Activity Levels For

Elementary And High School Students .................................... 7-14

Table 7-4. Average Hours Spent Per Day in a Given Location and Activity Level For

Elementary and High School Students .................................... 7-14

Table 7-5. Distribution Patterns of Daily Inhalation Rates For Elementary (EL) And High

School (HS) Students Grouped by Activity Level ............................ 7-15

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Table 7-6. Summary of Average Inhalation Rates (m3

/hr) by Age Group And Activity Levels for

Laboratory Protocols .................................................. 7-16

Table 7-7. Summary of Average Inhalation Rates (m3/hr) by Age Group And Activity Levels in

Table 7-8. Comparisons of Estimated Basal Metabolic Rates (BMR) With Average Food-energy

Field Protocols ....................................................... 7-17

Intakes (EFD) For Individuals Sampled in The 1977-78 NFCS ................. 7-18

Table 7-9. Daily Inhalation Rates Calculated From Food-energy Intakes ............... 7-19

Table 7-10. Daily Inhalation Rates Obtained From The Ratios Of Total Energy Expenditure to

Basal Metabolic Rate (BMR) ........................................... 7-20

Table 7-11. Inhalation Rates For Short-term Exposures ............................ 7-21

Table 7-12. Mean, Median, and SD of Respiratory Rate According to Waking or Sleeping in

618 Infants and Children Grouped in Classes of Age ......................... 7-22

Table 7-13. Descriptive Statistics for Daily Average Ventilation Rate (L/min) in Males, by Age

Table 7-14. Descriptive Statistics for Daily Average Ventilation Rate (L/min) in Females, by

Category ............................................................ 7-24

Age Category ........................................................ 7-25

Table 7-15. Average Time Spent Per Day Performing Activities Within Specified Intensity

Categories, and Average Ventilation Rates Associated With These Activity Categories,

for Males According to Age Category ..................................... 7-26

Table 7-16. Average Time Spent Per Day Performing Activities Within Specified Intensity

Categories, and Average Ventilation Rates Associated With These Activity Categories,

for Females According to Age Category ................................... 7-29

Table 7-17. Descriptive Statistics for Daily Average Ventilation Rate (m3/day) in Males, by Age

Category ............................................................ 7-32

Table 7-18. Descriptive Statistics for Daily Average Ventilation Rate (m3/day) in Females, by

Table 7-19. Descriptive Statistics for Duration of Time (hr/day) Spent Performing Activities

Within the Specified Activity Category, by Age and Gender Categories

Age Category ........................................................ 7-33

................................................................... 7-34

Table 7-20. Confidence in Inhalation Rate Recommendations ....................... 7-36

Table 7-21. Summary of Recommended Values For Inhalation ...................... 7-37

Table 8-1. Total Body Surface Area of Male Children in Square Metersa ............... 8-17

Table 8-2. Total Body Surface Area of Female Children in Square Metersa ............. 8-18

Table 8-3. Percentage of Total Body Surface Area by Body Part For Children .......... 8-19

Table 8-4. Descriptive Statistics For Surface Area/body Weight (SA/BW) Ratios (m2

/kg) . 8-20

Table 8-6. Mean and Percentile Skin Surface Area (m2) Derived from EPA Analysis of

NHANES III (All Children) ............................................ 8-21

Table 8-7. Mean and Percentile Skin Surface Area (m2) Derived from EPA Analysis of

Table 8-8. Mean and Percentile Skin Surface Area (m2

) Derived from EPA Analysis of

NHANES III (Male Children) ........................................... 8-22

NHANES III (Female Children) ......................................... 8-23

Table 8-9. Summary of Field Studies ........................................... 8-24

Table 8-10. Geometric Mean and Geometric Standard Deviations of Solids Adherence by

Activity and Body Region .............................................. 8-25

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Table 8-11. Summary of Groups Assayed in Round 2 of Field Measurements ........... 8-26

Table 8-12. Attire for Individuals within Children’s Groups Studied .................. 8-27

Table 8-13. Geometric Means (Geometric Standard Deviations) of Round 2 Post-activity

Loadings ............................................................ 8-28

Table 8A-1. Estimated Parameter Values for Different Age Intervals ................. 8A-4

Table 8A-2. Summary of Surface Area Parameter Values for the Dubois and Dubois Model

Table 8-14. Summary of Controlled Green House Trials - Children Playing ............ 8-29

Table 8-15. Preactivity Loadings Recovered from Greenhouse Trial Children Volunteers . 8-30

Table 8-19. Confidence in Solids Adherence to Skin Recommendations ............... 8-32

.................................................................. 8A-5

Table 9-1. Mean Time Spent (minutes) Performing Major Activities Grouped by Age, Sex and

Type of Day ......................................................... 9-16

Table 9-2. Mean Time Spent (minutes) in Major Activities Grouped by Type of Day for Five

Table 9-3. Mean Time Spent Indoors and Outdoors Grouped by Age and Day of the Week

Table 9-5. Mean Time Spent (minutes/day) in Various Microenvironments Grouped by Total

Table 9-6. Mean Time Spent (minutes/day) in Various Microenvironments by Type of Day for

Table 9-7. Mean Time Spent (minutes/day) in Various Microenvironments by Age Groups for

Table 9-8. Mean Time (minutes/day) Children Ages 12 Years and Under Spent in Ten Major

Different Age Groups ................................................. 9-17

................................................................... 9-18

Table 9-4. Mean Time Spent at Three Locations for both CARB and National Studies (ages 12

years and older) ...................................................... 9-19

Population and Gender (12 years and over) in the National and CARB Data ....... 9-20

the California and National Surveys ...................................... 9-21

the National and California Surveys ...................................... 9-22

Activity Categories for All Respondents ................................... 9-23

Table 9-9. Mean Time Children Spent in Ten Major Activity Categories by Age a ....... 9-24

Table 9-10. Mean Time Children Ages 12 Years and Under Spent in Ten Major Activity

Categories Grouped by Seasons and Regions ............................... 9-25

Table 9-11. Mean Time Children Ages 12 Years and Under Spent in Six Major Location

Categories for All Respondents (minutes/day) .............................. 9-26

Table 9-12. Mean Time Children Spent in Six Location Categories Grouped by Age and Gender

................................................................... 9-27

Table 9-14. Mean Time Children Spent in Proximity to Two Potential Exposures Grouped by 

All Respondents, Age, and Gender ....................................... 9-29

Table 9-15. Mean Time Spent Indoors and Outdoors Grouped by Age ................ 9-30

Table 9-16. Water and Soil Contact Exposure Factors ............................. 9-31

Table 9-17. Number of Showers Taken Per Day .................................. 9-31

Table 9-18. Time (minutes) Spent Taking a Shower and Spent in the Shower Room After

Taking a Shower by the Number of Respondents ............................ 9-32

Table 9-19. Time Spent Taking a Shower and Spent in the Shower Room Immediately After

Showering .......................................................... 9-32

Table 9-20. Time spent bathing, showering, and in bathroom after bathing and showering

(distribution) ........................................................ 9-33

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Table 9-21.Time spent bathing, showering, and in bathroom after bathing and showering

(percentiles) ......................................................... 9-34

Table 9-22. Range of Number of Times Washing the Hands at Specified Daily Frequencies by

Table 9-23. Number of Minutes Spent Working or Being Near Excessive Dust in the Air

Table 9-24. Range of Number of Times per Day a Motor Vehicle was Started in a Garage or

the Number of Respondents ............................................. 9-35

(minutes/day) ........................................................ 9-35

Carport and Started with the Garage Door Closed ........................... 9-36

Table 9-25. Number of Minutes Spent Playing on Dirt, Grass ....................... 9-37

Table 9-26. Number of Minutes Spent Playing on Dirt, Sand/Gravel, or Grass (minutes/day)

................................................................... 9-38

Table 9-27. Number of Times Swimming in a Month in Freshwater Swimming Pool by the

Number of Respondents ................................................ 9-39

Table 9-28. Number of Minutes Spent Swimming in a Month in Freshwater Swimming Pool

(minutes/month) ...................................................... 9-39

Table 9-29. Time Spent Sleeping/Napping: Whole Population and Doers Only: Percentile Values

................................................................... 9-40

Table 9-30. Time Spent Attending School Full-Time: Whole Population and Doers Only:

Percentile Values ..................................................... 9-40

Table 9-31. Time Spent in Active Sports: Whole Population and Doers Only: Percentile Values

................................................................... 9-41

Table 9-32. Time Spent on Exercise: Whole Population and Doers Only: Percentile Values

Table 9-33. Time Spent on Outdoor Recreation: Whole Population and Doers Only: Percentile

Table 9-34. Time Spent on Walking: Whole Population and Doers Only: Percentile Values

................................................................... 9-41

Values ............................................................. 9-42

................................................................... 9-42

Table 9-35. Time Spent Bathing: Whole Population and Doers Only: Percentile Values . . . 9-43

Table 9-36. Time Spent Eating: Whole Population and Doers Only: Percentile Values .... 9-43

Table 9-37. Time Spent at Restaurants: Whole Population and Doers Only: Percentile Values

................................................................... 9-44

Table 9-38. Time Spent Indoors at School: Whole Population and Doers Only: Percentile Values

................................................................... 9-44

Table 9-39. Time Spent on School Grounds/Playgrounds: Whole Population and Doers Only:

Percentile Values ..................................................... 9-45

Table 9-40. Time Spent at Home in Kitchen: Whole Population and Doers Only: Percentile

Table 9-41. Time Spent at Home in Living Room/Family Room/Den: Whole Population and

Values ............................................................. 9-46

Doers Only: Percentile Values ........................................... 9-46

Table 9-42. Time Spent at Home in Dining Room: Whole Population and Doers Only: Percentile

Values ............................................................. 9-47

Table 9-43. Time Spent at Home in Bathroom: Whole Population and Doers Only: Percentile

Values ............................................................. 9-47

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Table 9-44. Time Spent at Home in Bedroom: Whole Population and Doers Only: Percentile

Values ............................................................. 9-48

Table 9-45. Time Spent at Home in Study/Office: Whole Population and Doers Only: Percentile

Table 9-46. Time Spent at Home in Garage: Whole Population and Doers Only: Percentile

Table 9-47. Time Spent at Home: All Rooms Combined: Whole Population and Doers Only:

Table 9-49. Time Spent in a Truck (Pickup or Van): Whole Population and Doers Only:

Table 9-50. Time Spent in a Truck (Not Pickup or Van): Whole Population and Doers Only:

Table 9-53. Time Spent on an Airplane: Whole Population and Doers Only: Percentile Values

Table 9-55. Total Time Spent Inside Vehicles: Whole Population and Doers Only: Percentile

Table 9-56. Time Spent Inside Grocery/Convenience Stores, Other Stores, and Malls: Whole

Table 9-58. Statistics for 24-hour Cumulative Number of Minutes Spent with Smokers Present

Table 9-61. Aggregate Time Spent (minutes/day) At-Home in Activity Groups by Adolescents

Table 9-62. Comparison of Mean Time (minutes/day) Spent At-Home by Gendera (Adolescents)

Table 9-63. Comparison of Mean Time (minutes/day) Spent At-Home by Gender and Age for

Table 9-65. Number of Hours Per Day Children Spend in Various Microenvironments by Age

Table 9-66. Average Number of Hours Per Day Children Spend Doing Various Macroactivities

Table 9-67. Number of Hours Per Day Children Spend in Various Microenvironments by Age ­

Table 9-68. Number of Hours Per Day Children Spend in Various Macroactivities While

Table 9-69. Number and percentage of respondents with children and those reporting outdoor

Values ............................................................. 9-48

Values ............................................................. 9-49

Percentile Values ..................................................... 9-49

Table 9-48. Time Spent in an Car: Whole Population and Doers Only: Percentile Values . . 9-50

Percentile Values ..................................................... 9-50

Percentile Values ..................................................... 9-51

Table 9-51. Time Spent on a Bus: Whole Population and Doers Only: Percentile Values . . . 9-51

Table 9-52. Time Spent on a Train: Whole Population and Doers Only: Percentile Values . 9-52

................................................................... 9-52

Table 9-54. Time Spent on a Boat: Whole Population and Doers Only: Percentile Values . . 9-53

Values ............................................................. 9-53

Population and Doers Only: Percentile Values .............................. 9-54

Table 9-57. Average Time Spent Inside and Outside, By Age Category ................ 9-54

................................................................... 9-55

Table 9-59. Gender and Age Groups ........................................... 9-56

Table 9-60. Assignment of At-Home Activities to Ventilation Levels for Children ....... 9-57

and Childrena ........................................................ 9-58

................................................................... 9-58

Childrena ........................................................... 9-58

Table 9-64. Number of Person-Days/Individualsa

 for Children in CHADa Database ...... 9-59

................................................................... 9-60

While Indoors at Home ................................................ 9-61

Recast Into New Standard Age Categories ................................. 9-62

Indoors at Home - Recast Into New Standard Age Categories .................. 9-63

playa

 activities in both warm and cold weather .............................. 9-64

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Table 9-70. Play frequency and duration for all child players (from SCS-II data) ........ 9-64

Table 10-2. Number of Minutes Spent in Activities Working with or Near Household Cleaning

Table 10-5. Number of Respondents Indicating that Pesticides Were Applied by a Professional

Table 10-6. Number of Respondents Reporting Pesticides Applied by the Consumer at Home To

Table 11-1. Smoothed Percentiles of Weight (In Kg) by Sex And Age: Statistics From NCHS

Table 11-2. Weight in Kilograms For Males 2 Months-19 Years of Age– Number Examined,

Table 11-3. Weight in Kilograms For Females 6 Months-19 Years of Age– Number Examined,

Table 11-5. Body Weight Estimates (in kilograms) by Age and Gender, U.S. Population 1988-94

Table 11-7. Mean Body Weight (kilograms) by Age and Gender Across Multiple Surveys

Table 11-8. Mean and Percentile Body Weights (kg) Derived from NHANES III (All Children)

Table 11-9 Mean and Percentile Body Weights (kg) Derived from NHANES III (Male Children)

Table 11-10. Mean and Percentile Body Weights (kg) Derived from NHANES III (Female

Table 9-71. Hand washing and bathing frequency for all child players (from SCS-II data) . 9-65

Table 9-72 NHAPS and SCS-II play durationa comparison .......................... 9-65

Table 9-73. NHAPS and SCS-II hand wash frequency comparison ................... 9-66

Table 9-77. Confidence in Activity Patterns Recommendations ...................... 9-70

Table 10-1. Consumer Products Commonly Found in Some U.S. Householdsa .......... 10-4

Agents Such as Scouring Powders or Ammonia (minutes/day) ................. 10-7

Table 10-3. Number of Minutes Spent Using Any Microwave Oven (minutes/day) ....... 10-7

Table 10-4. Number of Respondents Using a Humidifier at Home ................... 10-8

at Home to Eradicate Insects, Rodents, or Other Pests at Specified Frequencies .... 10-9

Eradicate Insects, Rodents, or Other Pests at Specified Frequencies ............. 10-9

And Data From Fels Research Institute, Birth to 36 Months ......................... 11-7

Mean, and Selected Percentiles, by Age Category: United States, 1976-1980a ..... 11-8

Mean, and Selected Percentiles, by Age Category: United States, 1976-1980a ..... 11-9

Table 11-4. Statistics for Probability Plot Regression Analyses: Natural Log of Body Weights 6

Months to 20 Years of Age ............................................ 11-10

.................................................................. 11-11

Table 11-6. Body Weight Estimates (in kilograms) by Age, U.S. Population 1988-94 .... 11-12

.................................................................. 11-13

.................................................................. 11-14

.................................................................. 11-14

Children) .......................................................... 11-15

Table 11-11. Summary of Recommended Values for Body Weight .................. 11-15

Table 11-12. Confidence in Body Weight Recommendations ....................... 11-16

LIST OF FIGURES 

Figure 1-1. Schematic of Dose and Exposure: Oral Route .......................... 1-17

Figure 7-1. 5th, 10th, 25th, 50th, 75th, 90th, and 95th Smoothed Centiles by Age in Awake

Subjects ............................................................ 7-23

Figure 7-2. 5th, 10th, 25th, 50th, 75th, 90th, and 95th Smoothed Centiles by Age in Asleep

Subjects ............................................................ 7-23

Figure 8-1. Schematic of Dose and Exposure: Dermal Route ......................... 8-2

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Figure 8-2. Skin Coverage as Determined by Fluorescence vs. Body Part for Adults 

Transplanting Plants and for Children Playing in Wet Soils .................... 8-33

Figure 8-3. Gravimetric Loading vs. Body Part for Adult Transplanting Plants in Wet Soil

and for Children Playing in Wet and Dry Soils .............................. 8-33

Figure 11-1. Weight by Age percentiles for Girls Aged Birth-36 Months .............. 11-17

Figure 11-2. Weight by Age Percentiles for Boys Aged Birth-36 Months ............. 11-18

Figure 11-3. Mean Body Weight Estimates, U.S. Population, 1988-94 ............... 11-19

Figure 11-4. Median Body Weights Estimates, U.S. Population, 1988-94 ............. 11-20

xvii 
PREFACE 

The Exposure Factors Program of the of the U.S. Environmental Protection Agency’s 

(EPA’s) Office of Research and Development (ORD) has three main goals: (1) provide updates 

to the Exposure Factors Handbook and the Child-Specific Exposure Factors Handbook; (2) 

identify exposure factors data gaps and needs in consultation with clients; and (3) develop 

companion documents to assist clients in the use of exposure factors data. The activities under 

each goal are supported by and respond to the needs of the various program offices. 

The National Center for Environmental Assessment (NCEA) of EPA’s Office of 

Research and Development (ORD) has prepared this handbook to address factors commonly 

used in exposure assessments for children. Children may be more heavily exposed to 

environmental toxicants than adults. They consume more of certain foods and water and have 

higher inhalation rates per pound of body weight than adults. Young children play close to the 

ground and come into contact with contaminated soil outdoors and with contaminated dust on 

surfaces and carpets indoors. As another example, exposure to chemicals in breast milk affects 

infants and young children. 

The National Center for Environmental Assessment has published the Exposure Factors 

Handbook in 1997. This document includes exposure factors and related data on children, as 

well as adults. However, the EPA Program Offices identified the need to prepare a document 

specifically for children’s exposure factors. The goal of the Child-Specific Exposure Factors 

Handbook is to fulfill this need. 

This Handbook was first offered to the public in 2002. Since that time, EPA has 

developed a standardized set of age categories to be used for children’s exposure assessment. 

The use of a standard set of age categories is intended to permit easier comparison of data among 

multiple sources and to allow consistency between different types of exposure factors. 

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EXECUTIVE SUMMARY 

This Child-Specific Exposure Factors Handbook has been prepared to focus on various 

factors used in assessing exposure, specifically for children ages 0 - 21 years old. This handbook 

provides nonchemical-specific data on exposure factors for the EPA recommended set of 

childhood age groups in the following areas: 

C breast milk ingestion (chapter 2); 

C food ingestion, including homegrown foods and other dietary-related data 

(chapter 3); 

C drinking water ingestion (chapter 4); 

C soil ingestion (chapter 5); 

C hand-to-mouth and object-to-mouth activity (chapter 6); 

C dermal exposure factors such as surface areas and soil adherence (chapter 7); 

C inhalation rates (chapter 8); 

C duration and frequency in different locations and various microenvironments 

(chapter 9); 

C duration and frequency of consumer product use (chapter 10); and 

C body weight data (chapter 11) 

The handbook was first published in 2002. Subsequently, recognizing that exposures 

among infants, toddlers, adolescents, and teenagers can vary significantly, the U.S. 

Environmental Protection Agency (EPA) published its “Guidance on Selecting Age Groups for 

Monitoring and Assessing Childhood Exposures to Environmental Contaminants (U.S. EPA. 

2005a).” To the extent possible, source data for the independent studies cited in the earlier 

version of this Handbook were obtained and re-analyzed to conform to the standard age 

categories. This update and revision of the 2002 interim final Child-specific Exposure Factors 

Handbook is designed specifically to complement EPA’s recommended set of childhood age 

groups: 

< Less than 12 months old: birth to <1 month, 1 to <3 months, 3 to <6 months, and 6 to <12 

months. 

< Greater than 12 months old: 1 to <2 years, 2 to <3 years, 3 to <6 years, 6 to <11 years, 11 

to <16 years, and 16 to <21 years. 

The data presented in this handbook have been compiled from various sources, which 

include EPA’s Exposure Factor Handbook (U.S. EPA, 1997b), government reports, and 

information presented in the scientific literature. The data presented are the result of analyses by 

the individual study authors. However, in some cases EPA has conducted analysis of published 

primary data to present results for the recommended age groups. Studies presented in this 

handbook were chosen because they were seen as useful and appropriate for estimating exposure 

factors based on the following considerations: level of peer review, accessibility, reproducibility, 

focus on exposure factor of interest, pertinence of data to the U.S., primary data, currency of 

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information, adequacy of data collection period, validity of approach, representativeness of the 

population, variability in the population, minimal (or defined) bias in study design, and minimal 

(or defined) uncertainty in the data. Overall confidence ratings of high, medium, or low were 

derived for the various exposure factors based on the evaluation of the elements described above. 

Many scientific studies were reviewed for possible inclusion in this handbook. The 

handbook contains summaries of selected studies published through June 2006. Generally, 

studies were designated as “key” or “relevant” studies. Key studies were considered the most 

useful for deriving recommendations; while relevant studies provided applicable or pertinent 

data, but not necessarily the most important for a variety of reasons (e.g., data were outdated, 

limitations in study design). The recommended values for exposure factors are based on the 

results of key studies. EPA’s procedure for developing recommendations was as follows: 

1. Key studies were evaluated in terms of both quality and relevance to specific populations 

(general U. S. population, age groups, gender, etc.). The criteria for assessing the quality 

of studies are described in Section 1.4. 

2. If only one study was classified as key for a particular factor, the mean value from that 

study was selected as the recommended central tendency value for that population. If 

multiple key studies with reasonably equal quality, relevance, and study design 

information were available, a weighted mean (if appropriate, considering sample size and 

other statistical factors) of the studies was chosen as the recommended mean value. If 

the key studies were judged to be unequal in quality, relevance, or study design, the range 

of means is presented and the user of this handbook should employ judgment in selecting 

the most appropriate value for the lifestage or local population of interest. 

3. The variability of the factor across the lifestage was discussed. This document attempts 

to characterize the variability of each of the factors. Variability refers to true 

heterogeneity or diversity in a population. Differences among individuals in a population 

are referred to as inter-individual variability, differences for one individual over time is 

referred to as intra-individual variability. Since most of the studies used to derive 

exposure factors data are short term in nature, they present the variability in short term 

exposures across a population sample and often do not allow analysis of either intertemporal variability within individuals nor inter-individual variability of long term 

average exposures. Inter-individual variability in this handbook is characterized in one 

or more of the following ways: (1) as a table with various percentiles or ranges of values; 

(2) as analytical distributions with specified parameters; and/or (3) as a qualitative 

discussion. 

4. Uncertainties were discussed in terms of data limitations, the range of circumstances over 

which the estimates were (or were not) applicable, possible biases in the values 

themselves, a statement about parameter uncertainties (measurement error, sampling 

error) and model or scenario uncertainties if models or scenarios were used to derive the 

recommended value. 

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5. Finally, EPA assigned a confidence rating of low, medium or high to each recommended 

value. This rating is not intended to represent an uncertainty analysis; rather, it 

represents EPA’s judgment on the quality of the underlying data used to derive the 

recommendation. 

Most of the data presented in this handbook are derived from studies that target (1) the 

general population (e.g., USDA food consumption surveys) or (2) a sample population from a 

specific area or group (e.g., Davis et al. (1990) soil ingestion study using children from the threecity area in southeastern Washington State). The decision as to whether to use site-specific or 

national values for an assessment may depend on the quality of the competing data sets as well 

as on the purpose of the specific assessment. 

It is important to note that the recommended values were derived solely from EPA’s 

interpretation of the available data. Different values may be appropriate for the user in 

consideration of policy, precedent, strategy, or other factors (e.g., more up-to-date data of better 

quality and more representative of the population of concern). 

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AUTHORS, CONTRIBUTORS, AND REVIEWERS 

The National Center for Environmental Assessment (NCEA), Office of Research and 

Development was responsible for the preparation of this handbook. The 2001 edition was 

prepared by the Exposure Assessment Division of Versar Inc. in Springfield, Virginia, under 

EPA Contract No. 68-W-99-041. The 2005 revision was produced by the same group under EPA 

Contract No. EP-W-04-035 Jacqueline Moya served as Work Assignment Manager for both the 

original and the revision, providing overall direction, technical assistance, and serving as 

contributing author. 

AUTHORS WORD PROCESSING 

Versar, Inc. Versar, Inc.

Christopher Greene Susan Perry

Linda Phillips Valerie Schwartz

Patricia Wood

Kathleen Saunders-Coon

Marit Espevik

Todd Perryman

Clarkson Meredith

Diane Sinkowski

Nica Mostaghim

U.S. EPA

Jacqueline Moya

Laurie Schuda

John Schaum

The following EPA individuals reviewed an earlier draft of this document and provided 

valuable comments: 

Marcia Bailey, U.S. EPA, Region X 

Gary Bangs, U.S. EPA, Risk Assessment Forum, Office of Research and Development 

Denis R. Borum, U.S. EPA, Office of Water, Health and Ecological Criteria Division 

Dave Crawford, U.S. EPA, Office of Solid Waste 

Becky Cuthbertson, U.S. EPA, Office of Solid Waste 

Michael Dellarco, U.S. EPA, National Center for Environmental Assessment 

Lynn Delpire, U.S. EPA, Office of Prevention, Pesticides, and Toxic Substances 

Jeff Evans, U.S. EPA, Office of Pesticide Programs 

Cathy Fehrenbacher, U.S. EPA, Office of Prevention, Pesticides, and Toxic Substances 

Michael Firestone, U.S. EPA, Office of Children’s Health Protection 

Brenda Foos, U.S. EPA, Office of Children’s Health Protection 

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Henry Kahn, U.S. EPA, National Center for Environmental Assessment 

Youngmoo Kim, U.S. EPA, Region VI 

Steve Kroner, U.S. EPA, Office of Solid Waste 

Tom McCurdy, U.S. EPA, National Exposure Research Laboratory 

David Miller, U.S. EPA Office of Pesticide Programs 

Deirdre Murphy, U.S. EPA, Office of Air Quality Planning and Standards 

Steve Nako, U.S. EPA, Office of Pesticide Programs 

Marian Olsen, U.S. EPA, Region II 

Glenn Rice, U.S. EPA, National Center for Environmental Assessment 

Harvey Richmond, U.S. EPA, Office of Air Quality Planning and Standards 

David Riley, U.S. EPA Region VI 

Marybeth Smuts, U.S. EPA, Region I 

Marc Stifelman, U.S. EPA, Region X 

Valerie Zartarian, U.S. EPA, National Exposure Research Laboratory 

In addition, the National Exposure Research Laboratory (NERL) of the Office of Research and 

Development made an important contribution to this handbook by conducting additional 

analyses of mouthing behavior data from the Davis 1995 study. Data analyses were conducted 

by Nicole Tulve. 

This document was reviewed by an external panel of experts. The panel was composed of the 

following individuals: 

[to be added upon review] 

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