TABLE OF CONTENTS

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
LIST OF TABLES

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

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

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

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

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

11.1 INTRODUCTION 

The average daily dose is a dose that is typically normalized to the average body weight 

of the exposed population. The purpose of this section is to describe key published studies on 

body weight for children in the general U.S. population, as described in the Exposure Factors 

Handbook (U.S. EPA, 1997). Recommended values are based on the results of these studies. 

11.2 BODY WEIGHT STUDIES 

11.2.1 Hamill et al., 1979 

A National Center for Health Statistics (NCHS) Task Force that included academic 

investigators and representatives from the Centers for Disease Control (CDC) Nutrition 

Surveillance Program selected, collated, integrated, and defined appropriate data sets to generate 

growth curves for the age interval from birth to 36 months (Hamill et al., 1979). The percentile 

curves were developed to assess the physical growth of children in the U.S. and are based on 

accurate measurements made on large, nationally representative samples of children. Smoothed 

percentile curves were derived for body weight by age for all children and independently for 

boys and for girls. The data used to construct the curves were provided by the Fels Research 

Institute, Yellow Springs, Ohio. These data came from an ongoing longitudinal study in which 

anthropometric data from direct measurements are collected regularly from approximately 1,000 

participants in various areas of the U.S. The NCHS used advanced statistical and computer 

technology to generate the growth curves. Table 11-1 presents the percentiles of weight by sex 

and age. Figures 11-1 and 11-2 present percentile values of body weight grouped by age for 

boys and for girls, respectively. Limitations of this study are that mean body weight values were 

not reported and the data are more than 25 years old. However, this study does provide body 

weight data for infants less than 6 months old, which are lacking in many other studies. 

11.2.2. National Center for Health Statistics, 1987 

Statistics on anthropometric measurements, including body weight, for the U.S. 

population were collected by NCHS through the second National Health and Nutrition 

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Examination Survey (NHANES II). NHANES II was conducted on a nationwide probability 

sample of 27,801 persons aged 6 months to 74 years from the civilian, noninstitutionalized 

population of the United States. A total of 20,322 individuals in the sample were interviewed 

and examined—a response rate of 73.1 percent. The survey began in February 1976 and was 

completed in February 1980. The sample was selected so that certain subgroups thought to be at 

high risk of malnutrition (persons with low incomes, preschool children, and the elderly) were 

oversampled. The estimates were weighted to reflect national population estimates. The 

weighting was accomplished by inflating examination results for each subject by the reciprocal 

of selection probabilities adjusted to account for those who were not examined, and-post 

stratifying by race, age, and sex. 

The NHANES II collected standard body measurements of sample subjects, including 

height and weight, that were made at various times of the day and in different seasons of the 

year. This technique was used because an individual’s weight may vary between winter and 

summer and may fluctuate with patterns of food and water intake and other daily activities 

(NCHS, 1987). Percentile data for children, by age, are presented in Table 11-2 for males, and 

in Table 11-3 for females. 

11.2.3. Burmaster and Crouch, 1997 

Burmaster and Crouch (1997) performed data analysis to fit normal and lognormal 

distributions to the body weights of females and males aged 9 months to 70 years. Exposure 

Factors Handbook (U.S. EPA, 1997) used a pre-published version of this paper. The numbers 

reported in Table 11-4 are based on the final paper and vary slightly from those reported in the 

Exposure Factors Handbook. 

Data used in this analysis were from the second survey of the National Center for Health 

Statistics, NHANES II, which included 27,801 persons 6 months to 74 years of age in the U.S. 

(Burmaster et al., 1997). The NHANES II data had been statistically adjusted for non-response 

and probability of selection, and stratified by age, sex, and race to reflect the entire U.S. 

population prior to reporting. Burmaster and Crouch conducted exploratory and quantitative data 

analyses and fit normal and lognormal distributions to percentiles of body weights of children, 

teens, and adults as a function of age. Cumulative distribution functions were plotted for female 

and male body weights on both linear and logarithmic scales. 

11-2
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The maximum likelihood estimation was used to fit lognormal distributions to the data. 

Linear and quadratic regression lines were fitted to the data. A number of goodness-of-fit 

measures were conducted on data generated. The investigators found that lognormal 

distributions give strong fits to the data for each gender across all age groups. Statistics for the 

lognormal probability plots for children aged 9 months to 20 years are presented in Table 11-4. 

These data can be used for further analyses of body weight distribution (i.e., application of 

Monte Carlo analysis). The reader is referred to the original study for a more detailed 

description. 

11.2.4 U.S. EPA, 2000 

EPA’s Office of Water has estimated body weights for children by age and gender using 

data from NHANES III, which was conducted from 1988 to 1994. NHANES III collected body 

weight data for approximately 15,000 children between the ages of 2 months and 17 years. 

Table 11-5 presents the body weight estimates in kilograms by age and gender. Table 11-6 

shows the body weight estimates for infants under the age of 3 months; Figures 11-3 and 11-4 

compare the body weights (mean and median) of males and females of various age groups, 

respectively. 

The limitations of these data are that the data were not available for infants under 2 

months old, and that the data are roughly over 12 years old. With the upward trends in body 

weight from NHANES II (1976-1980) to NHANES III, the data in Tables 11-5 and 11-6 may 

underestimate current body weights. Adjustment factors may be needed to update the estimates 

from 1988-1994 data to the present. However, the data are national in scope and represent the 

general children’s population. 

11.2.5 Ogden et al., 2004 

Ogden et al. (2004) analyzed trends in body weight measured by the National Health 

Examination Surveys II and III (NHES II and III), the National Health and Nutrition 

Examination Surveys I, II, and III (NHANES I, II, and III), and NHANES 1999-2002. The 

surveys covered the period from 1960 to 2002. Table 11-7 presents the measured body weights 

for various age groups as measured in NHES and NHANES. Population means were calculated 

using sample weights to account for variation in sampling for certain subsets of the U.S. 

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population. The data indicate that mean body weight has increased over the period analyzed. 

There is some uncertainty inherent in such an analysis, however, because of changes in sampling 

methods during the 42 year time span covered by the studies. Because this study is based on an 

analysis of NHANES data, its limitations are the same as those for that study. However, it does 

serve to illustrate the importance of the use of timely data when analyzing body weight. 

11.2.6 EPA Analysis of NHANES III Data 

The NHANES III, 1988-94 was conducted on a nationwide probability sample of 

approximately 33,994 persons aged 2 months and older, of which approximately 15,000 were 

children. The survey was designed to obtain nationally representative information on the health 

and nutritional status of the population of the United States through interviews and direct 

physical examinations. A number of anthropometrical measurements were taken for each 

participant in the study, including body weight. Unit nonresponse to the household interview 

was 14 percent, and an additional 8 percent did not participate in the physical examinations 

(including body weight measurements). 

Certain subpopulations were oversampled to ensure a prespecified minimum sample size 

for each analytic domain. These oversampled subpopulations include children, older persons, 

Mexican-Americans, African-Americans, and people living in certain geographic areas. Sample 

data were assigned weights to account both for the disparity in sample sizes for these groups and 

for other inadequacies in sampling, such as the presence of non-respondents. The weight for 

each participant was calculated as the reciprocal of the participant's probability of selection, with 

adjustments for other variabilities in sampling rates such as changes made to the sampling rates 

at the time of data collection. 

Using the data and the weighting factors from NHANES III, EPA calculated body weight 

statistics for the standard age categories. Mean and percentile values were calculated using the 

sampling weights provided for each individual in the data set. The mean value for a given group 

was calculated using the following formula: 

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where: 

= sample mean; 

xi = the ith observation; 

wi = sample weight assigned to observation xi. 

Percentile values were calculated by first calculating the sum of the weights for all observations 

in a given group and multiplying this sum by the percentile of interest (e.g., multiplying by 0.25 

to determine the 25th percentile). The observations were then ordered from least to greatest, and 

each observation was assigned a cumulative weight, equal to its own weight plus all weights 

listed before the observation. The first observation listed with a cumulative weight greater than 

the value calculated for the percentile of interest was selected. 

Table 11-8 presents the percentiles of body weight for all children by age category. 

Tables 11-9 and 11-10 present body weight by age category for male and female children, 

respectively. 

Limitations of these data are that the data were not available for infants younger than 2 

months old, and that the data are over 12 years old. As with EPA’s earlier analysis of NHANES 

II data with different age categories (U.S. EPA, 2000), the data in Tables 11-8 to 11-10 may 

underestimate current body weights due to an observed upward trend in body weights (Ogden et 

al., 2004). Adjustment factors may be needed to update the estimates from 1988-1994 data to 

the present. However, the NHANES data remain the principal source of body weight data 

collected nationwide from a large number of subjects. 

11.3 RECOMMENDATIONS 

The recommended values for body weight are summarized in Table 11-11. Table 11-12 

presents the confidence ratings for body weight recommendations. 

For infants (birth to 2 months), appropriate values for body weight may be selected from 

Table 11-1. These data (percentiles only) are presented for male and female infants. For older 

infants and children, means and percentiles may be selected from Tables 11-8 (all), 11-9 (males) 

and 11-10 (females). 

11-5
1 11.4 REFERENCES FOR CHAPTER 11 

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3 

4 

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Burmaster, D.E.; Crouch, E.A.C. (1997) Lognormal distributions for body weight as a function of age for males and 

females in the United States, 1976-1980. Risk Anal. 17(4):499-505. 

6 

7 

Hamill, P.V.V.; Drizd, T.A.; Johnson, C.L.; Reed, R.B.; Roche, A.F.; Moore, W.M. (1979) Physical growth: 

National Center for Health Statistics Percentiles. American J. Clin. Nutr. 32:607-609. 

8 

9 

10 

11 

12 

13 

National Center for Health Statistics (NCHS) (1987) Anthropometric reference data and prevalence of overweight, 

United States, 1976-80. Data from the National Health and Nutrition Examination Survey, Series 11, 

No. 238. Hyattsville, MD: U.S. Department of Health and Human Services, Public Health Service, National 

Center for Health Statistics. DHHS Publication No. (PHS) 87-1688. 

14 

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Ogden, C.L.; Fryar, C.D.; Carroll, M.D.; and Flegal, K.M. (2004). Mean Body Weight, Height, and Body Mass 

Index, United States 1960-2002. Advance Data from Vital and Health Statistics, No. 347, October 27, 2004. 

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17 

U.S. Department of Health and Human Services, Centers for Disease Control and Prevention, National Center 

for Health Statistics. 

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U.S. EPA (1989) Risk assessment guidance for Superfund, Volume I: Human health evaluation manual. 

Washington, DC: U.S. Environmental Protection Agency, Office of Emergency and Remedial Response. 

EPA/540/1-89/002. 

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U.S. EPA (1997) Exposure Factors Handbook. Washington, DC: Office of Research and Development. EPA/600­

P-95/002F. 

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U.S. EPA (2000) Memorandum entitled: Bodyweight estimates on NHANES III data, revised, Contract 68-C99-242, Work Assignment 0-1 from Bob Clickner, Westat Inc. to Helen Jacobs, U.S. EPA dated 

March 3, 2000. 

11-6
Table 11-1. Smoothed Percentiles of Weight (In Kg) by Sex And Age: Statistics From NCHS And Data From Fels 

Research Institute, Birth to 36 Months 

Sex and Age 

Smoothed Percentile a 

5th 10th 25th 50th 75th 90th 95th 

Weight in Kilograms 

Male 

Birth 2.54 2.78 3.00 3.27 3.64 3.82 4.15 

1 Month 3.16 3.43 3.82 4.29 4.75 5.14 5.38 

3 Months 4.43 4.78 5.32 5.98 6.56 7.14 7.37 

6 Months 6.20 6.61 7.20 7.85 8.49 9.10 9.46 

9 Months 7.52 7.95 8.56 9.18 9.88 10.49 10.93 

12 Months 8.43 8.84 9.49 10.15 10.91 11.54 11.99 

18 Months 9.59 9.92 10.67 11.47 12.31 13.05 13.44 

24 Months 10.54 10.85 11.65 12.59 13.44 14.29 14.70 

30 Months 11.44 11.80 12.63 13.67 14.51 15.47 15.97 

36 Months 12.26 12.69 13.58 14.69 15.59 16.66 17.28 

Female 

Birth 2.36 2.58 2.93 3.23 3.52 3.64 3.81 

1 Month 2.97 3.22 3.59 3.98 4.36 4.65 4.92 

3 Months 4.18 4.47 4.88 5.40 5.90 6.39 6.74 

6 Months 5.79 6.12 6.60 7.21 7.83 8.38 8.73 

9 Months 7.00 7.34 7.89 8.56 9.24 9.83 10.17 

12 Months 7.84 8.19 8.81 9.53 10.23 10.87 11.24 

18 Months 8.92 9.30 10.04 10.82 11.55 12.30 12.76 

24 Months 9.87 10.26 11.10 11.90 12.74 13.57 14.08 

30 Months 10.78 11.21 12.11 12.93 13.93 14.81 15.35 

36 Months 11.60 12.07 12.99 13.93 15.03 15.97 16.54 

a

Smoothed by cubic-spline approximation. 

Source: Hamill et al. (1979). 

11-7
Table 11-2. Weight in Kilograms For Males 2 Months-19 Years of Age– Number Examined, Mean, and Selected Percentiles, by Age Category: United States, 

1976-1980a 

Age 

Number of 

Persons 

Examined 

Mean 

(kg) 

Percentile 

5th 10th 15th 25th 50th 75th 85th 90th 95th 

birth to <1 month b - - - - - - - - - - -

1 to <2 months b - - - - - - - - - - -

2 to <3 months 103 6.6 5.3 5.5 5.7 5.9 6.8 7.2 7.6 7.8 8.4 

3 to <6 months 287 7.7 6.3 6.6 6.7 7.0 7.7 8.4 8.9 9.2 9.6 

6 to <12 months 589 9.4 7.5 7.9 8.1 8.6 9.4 10.2 10.6 10.9 11.4 

1 to <2 years 613 11.7 9.4 9.8 10.1 10.8 11.7 12.6 13.1 13.7 14.5 

2 to <3 years 627 13.7 11.4 11.8 12.2 12.6 13.6 14.6 15.2 15.8 16.5 

3 to <6 years 1556 18.0 13.7 14.6 14.9 15.7 17.5 19.7 21.0 22.0 24.0 

6 to <11 years 1373 30.7 19.5 21.1 22.1 24.0 28.5 35.2 40.5 43.5 48.7 

11 to <16 years 1037 55.2 34.0 36.5 38.7 42.8 53.0 63.0 69.4 74.8 84.3 

16 to <21 years 890 71.8 54.1 56.6 58.3 61.8 68.7 77.9 84.3 89.7 101.0 

Note: 1 kg = 2.2046 pounds. a

Includes clothing weight, estimated as ranging from 0.09 to 0.28 kilogram. b

 No data available for infants less than two months old.

Source: National Center for Health Statistics (1987).

11-8
Table 11-3. Weight in Kilograms For Females 6 Months-19 Years of Age– Number Examined, Mean, and Selected Percentiles, by Age Category: United States, 

1976-1980a 

Age 

Number 

of Persons 

Examined 

Mean 

(kg) 

Percentile 

5th 10th 15th 25th 50th 75th 85th 90th 95th 

birth to <1 month b - - - - - - - - - - -

1 to <2 months b - - - - - - - - - - -

2 to <3 months 131 6.0 4.7 5.1 5.2 5.6 6.0 6.5 7.1 7.3 7.8 

3 to <6 months 269 7.1 5.8 5.9 6.1 6.4 7.1 7.7 7.9 8.4 8.7 

6 to <12 months 574 8.8 7.2 7.5 7.7 8.0 8.7 9.4 10.1 10.4 10.8 

1 to <2 years 617 11.0 9.1 9.4 9.6 9.9 10.9 11.9 12.6 12.9 13.4 

2 to <3 years 597 13.4 10.8 11.2 11.6 12.1 13.2 14.6 15.4 15.6 16.3 

3 to <6 years 1658 18.0 13.3 14.0 14.5 15.4 17.2 19.7 21.1 22.6 25.1 

6 to <11 years 1321 30.6 19.0 20.5 21.3 23.4 28.9 35.0 39.6 44.3 50.2 

11 to <16 years 1144 53.2 34.1 37.2 40.4 45.2 51.6 60.0 67.2 70.6 78.2 

16 to <21 years 1001 62.2 46.7 48.2 49.7 52.2 58.9 68.3 74.7 80.8 92.6 

Note: 1 kg = 2.2046 pounds. a Includes clothing weight, estimated as ranging from 0.09 to 0.28 kilogram. b

 No data available for infants less than two months old. 

Source: National Center for Health Statistics (1987). 

11-9
Table 11-4. Statistics for Probability Plot Regression Analyses: Natural Log of Body Weights 6 Months to 

20 Years of Age 

Age Midpoint 

(yrs) 

Best-Fit Parameters for Lognormal Distribution (kg) 

Males Females 

μ 2

a F 2b μ 2a F 2b 

0.75 

1.5 

2.5 

3.5 

4.5 

5.5 

6.5 

7.5 

8.5 

9.5 

10.5 

11.5 

12.5 

13.5 

14.5 

15.5 

16.5 

17.5 

18.5 

19.5 

2.23 

2.46 

2.60 

2.75 

2.87 

2.98 

3.13 

3.21 

3.33 

3.43 

3.59 

3.69 

3.78 

3.88 

4.02 

4.09 

4.20 

4.19 

4.25 

4.26 

0.132 

0.119 

0.120 

0.114 

0.133 

0.138 

0.145 

0.151 

0.181 

0.165 

0.195 

0.252 

0.224 

0.215 

0.181 

0.159 

0.168 

0.167 

0.159 

0.154 

2.16 

2.38 

2.56 

2.69 

2.83 

2.98 

3.10 

3.19 

3.31 

3.46 

3.57 

3.71 

3.82 

3.92 

3.99 

4.00 

4.05 

4.08 

4.07 

4.10 

0.145 

0.129 

0.112 

0.136 

0.134 

0.164 

0.174 

0.174 

0.156 

0.214 

0.199 

0.226 

0.213 

0.215 

0.187 

0.156 

0.167 

0.165 

0.147 

0.149 

a

μ , - Natural log mean of body weight (kg). 2 b F2 - Natural log standard deviation of body weight (kg). 

Source: Burmaster et al. (1997). 

11-10
Table 11-5. Body Weight Estimates (in kilograms) by Age and Gender, U.S. Population 1988-94 

Age Sample Size Population 

Male and Female Male Female 

Median Mean Median Mean Median Mean 

2-6 months 1,020 1,732,702 7.4 7.4 7.6 7.7 7.0 7.0 

7-12 months 1,072 1,925,573 9.4 9.4 9.7 9.7 9.1 9.1 

1 year 1,258 3,935,114 11.3 11.4 11.7 11.7 10.9 11.0 

2 years 1,513 4,459,167 13.2 12.9 13.5 13.1 13.0 12.5 

3 years 1,309 4,317,234 15.3 15.1 15.5 15.2 15.1 14.9 

4 years 1,284 4,008,079 17.2 17.1 17.2 17.0 17.3 17.2 

5 years 1,234 4,298,097 19.6 19.4 19.7 19.3 19.6 19.4 

6 years 750 3,942,457 21.3 21.7 21.5 22.1 20.9 21.3 

7 years 736 4,064,397 25.0 25.5 25.4 25.5 24.1 25.6 

8 years 711 3,863,515 27.4 28.1 27.2 28.4 27.9 27.9 

9 years 770 4,385,199 31.8 32.7 32.0 32.3 31.1 33.0 

10 years 751 3,991,345 35.2 35.6 35.9 36.0 34.3 35.2 

11 years 754 4,270,211 40.6 41.5 38.8 40.0 43.4 42.8 

12 years 431 3,497,661 47.2 46.9 48.1 49.1 45.7 48.6 

13 years 428 3,567,181 53.0 55.1 52.6 54.5 53.7 55.9 

14 years 415 4,054,117 56.9 61.1 61.3 64.5 53.7 57.9 

15 years 378 3,269,777 59.6 62.8 62.6 66.9 57.1 59.2 

16 years 427 3,652,041 63.2 65.8 66.6 69.4 56.3 61.6 

17 years 410 3,719,690 65.1 67.5 70.0 72.4 60.7 62.2 

1 and older 31,311 251,097,002 66.5 64.5 73.9 89.0 80.8 80.3 

1-3 years 4,080 12,711,515 13.2 13.1 13.4 13.4 13.0 12.9 

1-14 years 12,344 56,653,796 24.9 29.9 25.1 30.0 24.7 29.7 

15-44 years 10,393 118,430,653 70.8 73.5 77.5 80.2 63.2 67.3 

Source: U.S. EPA, 2000. 

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

Age Sample Size Population 

Male and Female 

Median Mean 95% CI 

Newborn NA NA NA NA NA 

1 Month NA NA NA NA NA 

2 Months 243 408,837 6.3 6.3 6.1-6.4 

3 Months 190 332,823 7.0 6.9 6.7-7.1 

3 Months and 

Younger 

433 741,660 6.6 6.6 6.4-6.7 

NA = Not available.

CI = Confidence Intervals.

Source: U.S. EPA (2000).

11-12
Table 11-7. Mean Body Weight (kilograms) by Age and Gender Across Multiple Surveys 

Gender 

and 

NHES II, 1963-65 NHES III, 1966-70 NHANES I, 1971-74 NHANES II, 1976-80 NHANES III, 1988-94 NHANES 1999-2002 

Age 

(years) N mean std. 

err. 

N mean std. 

err. 

N mean std. 

err. 

N mean std. 

err. 

N mean std. 

err. 

N mean std. 

err. 

Male 

2 - - - - - - 298 13.6 0.2 370 13.4 0.1 644 13.6 0.1 262 13.7 0.1 

3 - - - - - - 308 15.6 0.1 421 15.5 0.1 516 15.8 0.2 216 15.9 0.2 

4 - - - - - - 304 17.7 0.1 405 17.6 0.1 549 17.6 0.2 179 18.5 0.2 

5 - - - - - - 273 20.2 0.2 393 19.7 0.1 497 20.1 0.2 147 21.3 0.5 

6 575 22.0 0.1 - - - 179 22.0 0.3 146 22.8 0.4 283 23.2 0.6 182 23.5 0.4 

7 632 24.7 0.2 - - - 164 24.9 0.4 150 24.9 0.4 269 26.3 0.4 185 27.2 0.4 

8 618 27.8 0.2 - - - 152 26.4 0.3 145 28.0 0.6 266 30.2 0.8 214 32.7 1.0 

9 603 31.2 0.4 - - - 169 31.6 0.8 141 30.7 0.6 281 34.4 1.0 174 36.0 0.7 

10 576 33.7 0.3 - - - 184 34.2 0.6 165 36.2 0.7 297 37.3 0.9 187 38.6 0.8 

11 595 38.2 0.3 - - - 178 38.8 0.8 153 39.7 0.9 281 42.5 0.9 182 43.7 1.1 

12 - - - 643 42.9 0.4 200 44.0 0.8 147 44.1 1.0 203 49.1 1.1 299 50.4 1.3 

13 - - - 626 50 0.5 174 49.9 1.0 165 49.5 1.2 187 54.0 1.0 298 53.9 1.9 

14 - - - 618 56.7 0.6 174 56.3 0.9 188 56.4 0.9 188 64.1 3.6 266 63.9 1.6 

15 - - - 613 61.6 0.4 171 60.3 1.2 180 61.2 1.0 187 66.9 1.9 283 68.3 1.1 

16 - - - 556 64.8 0.6 169 66.9 1.3 180 66.5 1.2 194 68.7 1.6 306 74.4 1.4 

17 - - - 458 68.1 0.4 176 68.6 1.1 183 66.7 0.8 196 72.9 1.3 313 75.6 1.4 

18 - - - - - - 124 74.3 1.3 156 71.1 1.2 176 71.3 1.7 284 75.6 1.1 

19 - - - - - - 136 72.6 1.3 150 71.8 0.8 168 73.0 2.2 270 78.2 1.3 

Female 

2 - - - - - - 272 13.0 0.1 330 12.8 0.1 624 13.2 0.1 248 13.3 0.1 

3 - - - - - - 292 15.0 0.2 367 14.8 0.1 587 15.4 0.1 178 15.2 0.2 

4 - - - - - - 281 16.8 0.2 388 16.8 0.2 537 17.9 0.3 191 17.9 0.3 

5 - - - - - - 314 19.7 0.3 369 19.4 0.3 554 20.2 0.2 186 20.6 0.6 

6 536 21.5 0.2 - - - 176 21.6 0.3 150 21.9 0.4 272 22.6 0.6 171 22.4 0.5 

7 609 24.2 0.2 - - - 169 24.3 0.4 154 24.6 0.5 274 26.4 0.8 196 25.9 0.5 

8 613 27.5 0.2 - - - 152 27.5 0.5 125 27.5 0.4 248 29.9 0.6 184 31.9 1.2 

9 581 31.4 0.4 - - - 171 32.0 0.6 154 31.7 0.7 280 34.4 1.2 183 35.4 0.7 

10 584 35.2 0.4 - - - 197 33.8 0.6 128 35.7 0.6 258 37.9 1.2 164 40.0 1.0 

11 525 39.8 0.4 - - - 166 41.2 0.8 143 41.4 0.9 275 44.1 1.1 194 47.9 1.3 

12 - - - 547 46.6 0.4 177 46.7 1.0 146 46.1 0.9 236 49.0 1.2 316 52.0 1.1 

13 - - - 582 50.5 0.5 198 51.8 1.0 155 50.9 1.2 220 55.8 1.6 321 57.7 1.4 

14 - - - 586 54.2 0.4 184 54.6 1.0 181 54.3 1.0 218 58.5 1.4 324 59.9 1.0 

15 - - - 503 56.5 0.5 167 56.6 0.9 144 55.0 0.8 191 58.1 1.1 266 61.1 1.7 

16 - - - 536 58.1 0.7 171 56.8 1.1 167 57.7 0.9 208 61.3 1.4 273 63.0 1.2 

17 - - - 442 57.6 0.6 150 59.5 1.6 134 59.6 1.0 201 62.4 1.2 256 61.7 1.2 

18 - - - - - - 141 58.2 1.1 156 59.0 1.0 175 61.2 1.9 243 65.2 1.5 

19 - - - - - - 130 59.5 1.4 158 59.8 1.0 177 63.2 1.9 225 67.9 1.2 

NHES = National Health Examination Survey; NHANES = National Health and Nutrition Examination Survey. 

Source: Ogden et al., 2004 

11-13 
Table 11-8. Mean and Percentile Body Weights (kg) Derived from NHANES III (All Children) 

Age 

Group N mean 

percentiles 

5th 10th 15th 25th 50th 75th 85th 90th 95th 

2 to <3 months 234 6.3 4.8 5.2 5.4 5.7 6.3 6.9 7.3 7.4 7.8 

3 to <5 months 556 7.4 5.9 6.2 6.4 6.7 7.4 7.9 8.6 8.9 9.4 

6 to <11 months 1163 9.1 7.3 7.7 7.8 8.3 9.1 9.9 10.4 10.7 11.2 

1 to <2 years 1230 11.4 9.1 9.5 9.8 10.2 11.3 12.2 12.8 13.3 14.0 

2 to <3 years 1224 13.5 10.9 11.4 11.9 12.4 13.4 14.6 15.3 15.8 16.3 

3 to <5 years 3214 18.0 13.5 14.3 14.8 15.6 17.4 19.7 21.1 22.2 24.5 

6 to <11 years 2694 30.6 19.2 20.8 21.6 23.6 28.8 35.0 40.0 43.8 49.2 

11 to <16 years 2181 54.2 34.0 36.7 39.5 44.0 52.0 61.9 68.1 72.7 81.4 

16 to <21 years 1891 67.0 48.0 50.7 52.5 56.0 64.1 74.2 80.5 85.8 98.3 

Note: No data are available for persons less than 2 months old. 

Source: EPA Analysis of NHANES III data 

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

Age 

Group N mean 

percentiles 

5th 10th 15th 25th 50th 75th 85th 90th 95th 

2 to <3 months 103 6.6 5.3 5.5 5.7 5.9 6.8 7.2 7.6 7.8 8.4 

3 to <5 months 287 7.7 6.3 6.6 6.7 7.0 7.7 8.4 8.9 9.2 9.6 

6 to <11 months 589 9.4 7.5 7.9 8.1 8.6 9.4 10.2 10.6 10.9 11.4 

1 to <2 years 613 11.7 9.4 9.8 10.1 10.8 11.7 12.6 13.1 13.7 14.5 

2 to <3 years 627 13.7 11.4 11.8 12.2 12.6 13.6 14.6 15.2 15.8 16.5 

3 to <5 years 1556 18.0 13.7 14.6 14.9 15.7 17.5 19.7 21.0 22.0 24.0 

6 to <11 years 1373 30.7 19.5 21.1 22.1 24.0 28.5 35.2 40.5 43.5 48.7 

11 to <16 years 1037 55.2 34.0 36.5 38.7 42.8 53.0 63.0 69.4 74.8 84.3 

16 to <21 years 890 71.8 54.1 56.6 58.3 61.8 68.7 77.9 84.3 89.7 101.0 

Note: No data are available for persons less than 2 months old. 

Source: EPA Analysis of NHANES III data 

11-14 
Table 11-10. Mean and Percentile Body Weights (kg) Derived from NHANES III (Female Children) 

Age 

Group N mean 

percentiles 

5th 10th 15th 25th 50th 75th 85th 90th 95th 

2 to <3 months 131 6.0 4.7 5.1 5.2 5.6 6.0 6.5 7.1 7.3 7.8 

3 to <5 months 269 7.1 5.8 5.9 6.1 6.4 7.1 7.7 7.9 8.4 8.7 

6 to <11 months 574 8.8 7.2 7.5 7.7 8.0 8.7 9.4 10.1 10.4 10.8 

1 to <2 years 617 11.0 9.1 9.4 9.6 9.9 10.9 11.9 12.6 12.9 13.4 

2 to <3 years 597 13.4 10.8 11.2 11.6 12.1 13.2 14.6 15.4 15.6 16.3 

3 to <5 years 1658 18.0 13.3 14.0 14.5 15.4 17.2 19.7 21.1 22.6 25.1 

6 to <11 years 1321 30.6 19.0 20.5 21.3 23.4 28.9 35.0 39.6 44.3 50.2 

11 to <16 years 1144 53.2 34.1 37.2 40.4 45.2 51.6 60.0 67.2 70.6 78.2 

16 to <21 years 1001 62.2 46.7 48.2 49.7 52.2 58.9 68.3 74.7 80.8 92.6 

Note: No data are available for persons less than 2 months old. 

Source: EPA Analysis of NHANES III data 

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

Population Table Reference Source 

birth to <1 month 

See Table 11-1 Hamill et al. (1979) 

1 to <2 months 

2 to <3 months 

See Tables 11-9 (all), 

11-10 (males), and 

11-11 (females) 

EPA analysis of 

NHANES III data 

3 to <5 months 

6 to <11 months 

1 to <2 years 

2 to <3 years 

3 to <5 years 

6 to <11 years 

11 to <16 years 

16 to <21 years 

11-15
Table 11-12. Confidence in Body Weight Recommendations 

Considerations Rationale Rating 

Study Elements 

• Level of peer review NHANES III was the major source for central tendency and percentile 

values. This analysis has not yet been published. Body weights of young 

infants (0-2 months) are derived from Hamill et al. (1979), a published 

study which received a high level of peer review 

Low for 

NHANES 

analysis; 

High for 

young 

infants 

• Accessibility NHANES III and Hamill et al. (1979) are available to the public. U.S. 

EPA (2000) is available upon request. 

High 

• Reproducibility Results can be reproduced by analyzing NHANES II data, NHANES III 

data, and the Fels Research Institute data. 

High 

• Focus on factor of interest The studies focused on body weight, the exposure factor of interest. High 

• Data pertinent to US The data represent the U.S. population. High 

• Primary data The primary data were generated from NHANES II and III data and Fels 

studies, thus these data are secondary. 

Medium 

• Currency The data were collected between 1976-1980 for Hamill et al. and 

NHANES II. U.S. EPA (2000) and EPA’s analysis of NHANES III using 

the new age groupings covered the years 1988-94. Ogden et al. (2004) 

covered the years 1960-2002. 

High for 

central 

tendency; 

medium for 

percentiles 

• Adequacy of data collection 

period 

The NHANES II study included data collected over a period of 4 years. 

Body weight measurements were taken at various times of the day and at 

different seasons of the year. NHANES III study included data collected 

over a 7-year period. 

High 

• Validity of approach Direct body weights were measured for both studies. For NHANES II, 

subgroups at risk for malnutrition were over-sampled. Weighting was 

accomplished by inflating examination results for those not examined and 

were stratified by race, age, and sex. The Fels data are from an ongoing 

longitudinal study where the data are collected regularly. 

High 

• Study size The sample size consisted of 28,000 persons for NHANES II. Author 

noted in Hamill et al. (1979) that the data set was large. NHANES III 

study included 14,387 individuals under the age of 21 years. 

High 

• Representativeness of the 

population 

Data collected focused on the U.S. population for both studies. High 

• Characterization of variability All studies characterized variability regarding age and sex. Additionally 

NHANES II characterized race (for Blacks, Whites and total populations) 

and sampled persons with low income. 

High 

• Lack of bias in study design 

(high rating is desirable) 

There are no apparent biases in the study designs for NHANES II. The 

study design for collecting the Fels data was not provided. 

MediumHigh 

• Measurement error For NHANES II and III, measurement error is expected to be low because 

body weights were performed in a mobile examination center using 

standardized procedures and equipment. Also, measurements were taken 

at various times of the day to account for weight fluctuations as a result of 

recent food or water intake. The authors of Hamill et al. (1979) report 

that study data are based on accurate direct measurements from an 

ongoing longitudinal study. 

High 

Other Elements 

• Number of studies There are two studies. Medium 

• Agreement between 

researchers 

There is consistency among the studies. High 

Overall Rating High 

11-16
Figure 11-1. Weight by Age percentiles for Girls Aged Birth-36 Months 

Source: Hamill et al. (1979). 

11-17 
Figure 11-2. Weight by Age Percentiles for Boys Aged Birth-36 Months 

Source: Hamill et al. (1979). 

11-18
Figure 11-3. Mean Body Weight Estimates, U.S. Population, 1988-94

Source: U.S. EPA (2000). 

11-19
Figure 11-4. Median Body Weights Estimates, U.S. Population, 1988-94 

Source: U.S. EPA (2000). 

11-20