1 

USER'S GUIDE FOR IEUBKWIN 

United States 

Environmental Protection 

Agency 

Office of Superfund Remediation 

and Technology Innovation 

EPA 9285.7-42 

May 2007 

540-K-01-005 

User’s Guide for the Integrated 

Exposure Uptake Biokinetic 

Model for Lead in Children 

(IEUBK) Windows®

Prepared for 

The Technical Review Workgroup for Metals and Asbestos (TRW) 

Prepared by 

Syracuse Research Corporation 

6225 Running Ridge Road 

North Syracuse, NY 13212 
 USER'S GUIDE FOR IEUBKWIN ii 

Disclaimer 

This document has been reviewed in accordance with U.S. EPA policy and is approved 

for publication. Mention of trade names or commercial products does not constitute 

endorsement or recommendation. 
 USER'S GUIDE FOR IEUBKWIN iii 

U.S. Environmental Protection Agency 

Technical Review Workgroup for Metals and Asbestos 

Members 

The members of the TRW Lead Committee are technical staff from EPA Regions, Office of Solid Waste 

and Emergency Response (OSWER) Headquarters, and Office of Research and Development National 

Center for Environmental Assessment (ORD/NCEA). Lead Committee members generally have an active 

interest and recognized scientific expertise in metals or asbestos risk assessment. For more information 

see: http://www.epa.gov/superfund/lead/trw.htm. 
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 USER'S GUIDE FOR IEUBKWIN v 

Table of Contents 

Disclaimer .....................................................................................................................................................ii 

Members ......................................................................................................................................................iii 

Table of Contents .......................................................................................................................................... v 

List of Tables ..............................................................................................................................................vii 

List of Figures .............................................................................................................................................. ix 

Acronyms and Abbreviations ...................................................................................................................... xi 

1.0 Introduction............................................................................................................................................ 1 

1.1 Purpose of the User's Guide ........................................................................................................ 1 

1.1.1 Overview of the IEUBKwin Model .................................................................................... 1 

1.2 Loading and Starting the Model .................................................................................................. 5 

2.0 Inputs ..................................................................................................................................................... 7 

2.1 Input Windows ............................................................................................................................ 9 

2.2 Detailed Descriptions of Input Options ..................................................................................... 10 

2.2.1 Air Data............................................................................................................................. 14 

2.2.2 Dietary Data ...................................................................................................................... 14 

2.2.3 Drinking Water Data......................................................................................................... 15 

2.2.4 Soil/Dust Data................................................................................................................... 15 

2.2.4.1 Lead in Soil .............................................................................................................. 15 

2.2.4.2 Lead in Dust ............................................................................................................. 16 

2.2.5 Maternal Data ................................................................................................................... 17 

2.2.6 Alternate Source Data ....................................................................................................... 17 

2.2.7 GI Values/Bioavailability ................................................................................................. 18 

2.2.8 Geometric Standard Deviation (GSD) .............................................................................. 18 

2.3 Save and Load Input Parameters ............................................................................................... 19 

3.0 Model Analysis .................................................................................................................................... 20 

3.1 Options for model analyses ....................................................................................................... 20 

3.2 Overview of Model Output........................................................................................................ 20 

3.3 Selecting Output Alternatives.................................................................................................... 21 

3.3.1 What Graphical Options are Included in IEUBKwin?...................................................... 21 

3.4 Computation Options................................................................................................................. 22 

3.4.1 Run a Single Simulation ................................................................................................... 22 

3.4.1.1 Single-Run Options ..................................................................................................... 23 

3.4.2 Calculating a Blood Lead Concentration Associated with Media-Specific 

Concentration.................................................................................................................... 23 

3.4.3 Run Multiple Simulations ................................................................................................. 24 

3.4.3.1 Multiple-Run Options................................................................................................... 24 

3.4.4 Run Batch Mode Simulation............................................................................................. 25 

4.0 Interpretation of Results....................................................................................................................... 27 

4.1 Understanding the Output.......................................................................................................... 27 
 USER'S GUIDE FOR IEUBKWIN vi 

5.0 Model Application and Documentation ............................................................................................... 29 

5.1 Model Application..................................................................................................................... 29 

5.2 Model Documentation (minimum requirements) ...................................................................... 30 

5.3 User Responsibilities ................................................................................................................. 30 

6.0 Example Scenarios............................................................................................................................... 31 

6.1 Simple Case Single Runs........................................................................................................... 31 

6.2 “Sum of Individual Risks” Approach ........................................................................................ 31 

6.3 Risk Assessment Using Grouped Data for a Neighborhood......................................................33 

6.4 Risk Assessment Using Neighborhood or Neighborhood-Scale Input...................................... 35 

7.0 References............................................................................................................................................ 38 

APPENDICES 

A: Using Spreadsheets with IEUBKwin ..................................................................................................... 40 

A.1 Importing IEUBKwin data to spreadsheet packages ...................................................................... 40 

A.2 Creating a batch mode data input file using a spreadsheet ............................................................. 43 

B: Probability Distribution Function.......................................................................................................... 44 

C: Short Sheets Currently Available .......................................................................................................... 46 
 USER'S GUIDE FOR IEUBKWIN vii 

List of Tables 

2–1. Default Values for IEUBKwin Model Parameters .............................................................. 11 

6–1. Simple Case Runs ................................................................................................................ 31 

6–2. Interpreted Results for Figure 6–1 ....................................................................................... 33 

6–3. Neighborhood Risk Estimation with Grouped Data ............................................................ 36 

6–4. Neighborhood Risk Estimation with Coarsely Grouped Data ............................................. 37 
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 USER'S GUIDE FOR IEUBKWIN ix 

List of Figures 

1-1. Biological Structure of the IEUBKwin Model. ...................................................................... 4 

2-1. Categories of Application of IEUBKwin. .............................................................................. 8 

3-1. The Impact of GSD on Plausible Geometric Mean PbB Distributions. ............................... 22 

6-1. Probability Density of Blood Lead in Houses 1 to 4. ........................................................... 32 

A-1. Export IEUBKwin Data Output to Microsoft Excel............................................................ 40 

A-2. Export IEUBKwin Data Output to Lotus 1-2-3................................................................... 41 

A-3. Creating a Batch Data file with Microsoft Excel................................................................. 42 
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 USER'S GUIDE FOR IEUBKWIN xi 

Acronyms and Abbreviations 

CERCLA Comprehensive Emergency Response Compensation Liability Act 

dL deciliter 

g gram 

GI gastrointestinal 

GM geometric mean 

GSD Geometric Standard Deviation 

IEUBKwin Integrated Exposure Uptake Biokinetic Model for Lead in Children, 

Windows version 

FDA Food and Drug Administration 

L liter 

LOC level of concern 

MSA Multiple Source Analysis 

MSD Mass fraction of soil to dust 

3 m cubic meters 

OSWER Office of Solid Waste and Emergency Response 

Pb lead 

PbB blood lead 

PbD dust lead 

PbS soil lead 

PDF Probability Density Function 

PRG Preli minary Remediation Goal 

RCRA Resource Conservation Recovery Act 

TRW Technical Review Workgroup for Metals and Asbestos 

μg microgram 
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1 

USER'S GUIDE FOR IEUBKWIN 

1.0 Introduction 

The Integrated Exposure Uptake Biokinetic Model for Lead (Pb) in Children, Windows (IEUBKwin)

is a stand-alone personal computer (PC)-compatible software package. The model utilizes four

 interrelated modules (exposure, uptake, biokinetic, and probability distribution) to estimate blood lead 

(PbB) levels in children exposed to lead (Pb)-contaminated media. IEUBKwin allows the user to 

estimate, for a hypothetical child or population of children, a plausible distribution of PbB concentrations centered on a geometric mean PbB concentration. The geometric mean PbB is predicted from 

available information about the child’s or children’s exposure to lead. From this distribution, the 

model estimates the risk (i.e., probability) that a child’s or a population of children’s PbB concentration

will exceed a certain level of concern (typically 10 μg/dL). 

IEUBKwin should be viewed as a tool for making rapid calculations and recalculations of an 

extremely complex set of equations which includes many exposure, uptake, and biokinetic 

parameters. It has been recommended as a risk assessment tool to support the implementation of 

the July 14, 1994, Office of Solid Waste and Emergency Response (OSWER) Directive entitled 

Revised Interim Soil Lead Guidance for Comprehensive Environmental Response Compensation 

Liability Act (CERCLA) Sites and Resource Conservation and Recovery Act (RCRA) Corrective 

Action Facilities, as well as the subsequent August 1998 OSWER Directive entitled Clarification 

to the 1994 Revised Interim Soil Lead Guidance for CERCLA Sites and RCRA Corrective Action 

Facilities. The development of the IEUBKwin model included Independent Validation and 

Verification and a limited peer review of the software and documentation. 

1.1 PURPOSE OF THE USER'S GUIDE 

This User’s Guide is intended to serve as a comprehensive reference for use of IEUBKwin. It 

provides the basics needed for accurate application and interpretation of the model, including 

how to install and run the model, model inputs, model analysis, model output, interpretation of 

model results, minimum requirements for risk assessment application, and example scenarios. 

Users of the model can refer to the IEUBK Guidance Manual (U.S. EPA, 1994) or the IEUBK 

Structure Paper (White et al., 1998) for supplemental information concerning the parameters and 

correct application of IEUBKwin. 

1.1.1 Overview of the IEUBKwin Model 

The focus of the integrated exposure uptake biokinetic (IEUBK) model for lead in children is the 

prediction of blood lead concentrations in young children exposed to lead from several sources 

and by several routes. The model is a four-step process that mathematically and statistically 

links environmental lead exposure to blood lead concentrations for a population of children (0-84 

months of age). Figure 1-1 provides a schematic showing the sources of exposure to 
2 

USER'S GUIDE FOR IEUBKWIN 

environmental lead and the absorption and processing of lead by the human body (IEUBK 

Guidance Manual, U.S. EPA, 1994). 

The four model components each reflect a different aspect of the overall biologic process: 

Exposure Component. Exposure can be thought of as the contact of a chemical, or other agent, 

with the absorption or exchange boundaries of an organism, such as the gut, lungs, and 

skin. Quantitation of a child’s exposure to lead (μg/day) requires estimation of the 

concentration of lead in the environmental media that the child contacts (usually μg/g, 

μg/m3

, or μg/L, multiplied by a term to describe the amount of contact the child has with 

the medium (usually g/day, m3/day, or liters/day), and a term for the duration of that 

contact (usually days). The results from the exposure component of the IEUBK model 

are estimated intake rates for the quantities of lead inhaled or ingested from 

environmental media. The media addressed by the IEUBK model include soil, house 

dust, drinking water, air, and food. Paint is usually addressed in terms of its contribution 

to the measured concentration of lead in soil or house dust. 

Uptake Component. The uptake component models the process by which lead intake (lead that 

has entered the child’s body through ingestion or inhalation) is transferred to the blood 

plasma. Uptake (μg/day) is the quantity of lead absorbed per unit time from portals of 

entry (gut, lung) into the systemic circulation of blood. Only a fraction of the lead 

entering the body through the respiratory or gastrointestinal (GI) tracts is actually 

absorbed into the systemic circulation. This absorption fraction is, by convention, termed 

bioavailability and provides the most convenient parameterization of the uptake process. 

The IEUBK model addresses the different bioavailabilities of lead from different 

environmental media and provides for a partial saturation of absorption at high levels of 

lead intake. 

Biokinetic Component. The biokinetic component of the IEUBK model is a mathematic 

expression of the movement of absorbed lead throughout the body over time by 

physiologic or biochemical processes. The biokinetic component converts the total lead 

uptake rate from the uptake component into an input to the central plasma-extracellular 

fluid (ECF) compartment. Transfer coefficients are used to model movement of lead 

between the internal compartments and to the excretion pathways. The quantities are 

combined with the total lead uptake rate to continuously recalculate the lead masses in 

each of the body compartments and especially the changing concentration of lead in 

blood. 

Variability. An important goal of the IEUBK model is to address variability in blood lead 

concentrations among exposed children. Children having contact with the same 

concentrations of environmental lead can develop very different blood lead 

concentrations due to differences in behavior, household characteristics, and individual 

patterns of lead uptake and biokinetics. The IEUBK model uses a log-normal probability 

distribution to characterize this variability. The biokinetic component output provides a 

central estimate of blood lead concentration, which is used to provide the geometric 

standard deviation (GSD). The recommended default value for this parameter (1.6) was 
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USER'S GUIDE FOR IEUBKWIN 

derived from empirical studies with young children where both blood and environmental 

lead concentrations were measured. 
4 

USER'S GUIDE FOR IEUBKWIN 

Air il 

l

Uri

Skin 

Hair 

llul

llul

i l 

Cells 

Ki

Diet Dust Paint So Water 

Lungs 

Lungs 

GI Tract 

GI Tract 

Exha ed 

Air 

Feces 

Feces 

ne 

Nails 

Plasma Extra-Ce ar Fluid 

Plasma Extra-Ce ar Fluid 

Trabecular 

Bone 

Cort ca

Bone 

Red 

Blood dney 

Other 

Soft 

Tissues 

Liver 

- Environmental Media 

- Body Compartments 

- Elimination Pools of the Body 

- Body Compartment or Elimination Pool Required in More Than One Component 

Figure 1-1. Biological Structure of the IEUBKwin Model. 
5 

USER'S GUIDE FOR IEUBKWIN 

1.2 LOADING AND STARTING THE MODEL 

IEUBKWIN.EXE; AIR.INP; 

MATERNAL.INP; MULTISRC.INP; 

WATER.INP; BATCHRUN.INP; 

DIET.INP; GIBIO.INP; 

OTHER.INP; SOIL.INP; 

BATCHRUN.DAT; UNINST.ISU 

The “IEUBKWIN.EXE” file is the main program file; the “*.INP” files contain the default values 

for the Parameter Input pull-down options; the “BATCHRUN.DAT” file is the example input file 

for batch mode runs; and the “UNINST.ISU” file is used by Windows to completely uninstall the 

program. 

Following extraction, the user must agree to the software license agreement, register the software 

with the U.S. EPA, and specify a location for installation. IEUBKwin is intended to be run as a 

desktop application rather than from a network installation. It is recommended that a local copy 

of the application be saved onto the PC from which it will be run. As part of the model 

installation, a desktop icon labeled IEUBKwin will be installed. To run the model, double-click 

the IEUBKwin icon from the Programs menu. A Disclaimer will appear on the screen. Read the 

Disclaimer then close the Disclaimer window by clicking on the <<Close>> button. 

The most current information pertaining to IEUBKwin model and Pb risk assessment is available 

on the Technical Review Workgroup (TRW) website. The TRW home page may be found at 

http://www.epa.gov/superfund/lead. 

Questions concerning the use and interpretation of IEUBKwin model may be submitted to the 

IEUBK technical support center via the TRW web page. 

IEUBKwin is menu driven, with on-line, context-sensitive help available in almost every menu 

or window. In addition to the buttons that provide quick access to commonly-used model 

features, the main pull-down menus and the associated options remain. The contents of each 

these menus are listed below: 

1. File Menu 

• Select Run Mode 

• Print 

• Print Setup 

• Close 

• Exit 

Under Select Run Mode the user may choose to run the model in Research or Site Risk 

Assessment mode, depending upon individual needs. If the user chooses to run the model in the 

Site Risk Assessment mode, the model will prompt the user for a user name, date, site name, and 

operable unit. In addition, the model will require the user to input a comment into a comment 

screen whenever the user modifies the default value of an input parameter. 
6 

USER'S GUIDE FOR IEUBKWIN 

2. Parameter Input Menu Options 

• Air Data 

• Dietary Data 

• Drinking Water Data 

• Soil/Dust Data 

• Maternal Data 

• Alternate Source Data 

• GI Values/Bioavailability 

• Reset All Parameters 

• Load Input From File 

• Save Input To File 

3. Computation Menu Options 

• Run the Model (Single Run) 

• Multiple Runs 

• Blood Pb vs. Media Pb 

• Find Blood Pb Concentration 

• Batch Mode Model Runs 

4. Output Menu Options 

• View Text Result File 

• Rename Text Result File 

• Rename Blood Media Graph File 

• Rename Single Run Graph File 

• Rename Multiple Run Graph File 

5. Graph Menu Options 

• Blood Pb Concentration vs. Media Pb Concentration 

• Distribution Probability Percent 

• Distribution Probability Density Histogram 

• Distribution Probability for Multiple Runs 

• Probability Density for Multiple Runs 

6. Help Options 

• Contact Information 

• General Help 

• Menu Information 

• File Extensions in IEUBKwin 

• Significant Figures in IEUBKwin 

• About IEUBKwin Lead Model 
7 

USER'S GUIDE FOR IEUBKWIN 

2.0 Inputs 

IEUBKwin contains more than 100 input parameters that are initially set to default values. Of 

these 100 input parameters, there are 46 external input parameters that may be changed by the 

user; the remaining internal model parameters are set to fixed default values. The default values 

represent national averages or plausible central values that were developed based on many years 

of research. However, to most effectively use the model, it is necessary to use valid site-specific 

information as much as is feasible. This section provides a brief description of how a user can 

change IEUBKwin parameters to better match the conditions at a specific site. 

The array of valid applications for which IEUBKwin can be used is as follows: 

Category A: One location. 

A1: One living unit, one child.1 

A2: One living unit, more than one child. 

A3: More than one living unit, more than one child, homogeneous 

media concentrations. 

Category B: Multiple locations, one neighborhood, homogeneous media 

concentrations. 

Category C: Multiple locations, one neighborhood, heterogeneous media 

concentrations. 

Category D: Multiple locations, more than one neighborhood, potentially 

heterogeneous neighborhood ingestion/absorption parameters. 

A single run of IEUBKwin is sufficient for categories A and B. Categories C and D require 

classification or disaggregation of the neighborhood into distinct exposure subgroups, with the 

possibility of different ingestion or absorption parameters for different neighborhoods in 

Category D. Neighborhood-scale and community-scale risk estimation requires aggregating the 

risk estimates for individuals or subgroups. The differences between these levels are sketched in 

Figure 2-1. Category A requires calculating only a single PbB distribution. Category B requires 

calculating a PbB distribution for each child, but since each child of the same age has the same 

exposure scenario, a single run of the model is sufficient to characterize risk for this subgroup. 

In Category C, there are different media concentrations for different individual. Risk estimates 

must be calculated for each individual or homogeneous subgroup, then added up across sites and 

children. Category D allows for the case where not only exposure concentrations, but other basic 

exposure and bioavailability parameters differ among the exposed groups. 

1

The IEUBK model is not intended to be used as a substitute for blood lead measurement 

and medical evaluation of a specific child at risk. Medical evaluation can take into account 

specific information on behavior and risk factors, such as nutritional status, that are beyond the 

scope of a broadly applicable environmental risk model. (See FAQ on PbB studies at 

(http://www.epa.gov/superfund/lead)). 
8 

USER'S GUIDE FOR IEUBKWIN 

A. 

B. 

C. 

Si

i i i

l ild 

Singl i

i l i

Si l ith homogeneous 

i

i i i

Probability 

Blood Lead 

Child 1 

Site 1 

Child 2 

Site 2 

Child 3 

Site 2 te 3 

Child 1 Ch ld 2 Ch ld 3 Ch ld 4 

Sing e ch

e s te of exposure 

Mult ple children or popu at on 

ngle location or ocations w

concentrations 

Multiple children or populat on in neighborhood 

Multiple s tes with exposures to d fferent media concentrat ons 

D. Multiple children or population in heterogeneous community 

or region, different neighbohood exposure scenarios 

Figure 2-1. Categories of Application of IEUBKwin. 
9 

USER'S GUIDE FOR IEUBKWIN 

2.1 INPUT WINDOWS 

There are seven parameter input windows where parameters can be modified to reflect the sitespecific conditions. IEUBKwin input options are button at the top of the screen and are as 

follows: 

• Air Data 

• Dietary Data 

• Drinking Water Data 

• Soil/Dust Data 

• Maternal Data 

• Alternative Source Data 

• GI Values/Bioavailability 

The parameter values shown in the input windows are set to EPA-specified default values. 

Where site-specific data are available, the user is encouraged to alter inputs for environmental 

media Pb concentrations. However, the user should change parameters such as the mass fraction 

of soil to dust (MSD), bioavailability, geometric standard deviation (GSD), soil ingestion rates, 

and dietary data only if the user has a thorough understanding of the methodology behind those 

parameters and valid site-specific monitoring data that are specifically applicable to the 

parameters. Generally, the TRW considers that “valid” site-specific information will reflect data 

quality indicators such as completeness, comparability, representativeness, precision, and 

accuracy. 

The user can reset any modified parameters to their default values by using the Reset All 

Parameters command on the Parameter Input pull-down menu. If further information about an 

input parameter or default value is required, consult the IEUBK Guidance Manual (U.S. EPA, 

1994). The input windows were designed to allow users to tab between fields to facilitate the 

data entry process. Note that a value is not saved for use in a model run until the user clicks the 

<<OK>> button on the input screen. If <<Cancel>> is selected (or if the window is closed using 

the “X” in the upper right corner of the window), the model retains the initial default values. The 

model does not substitute default values for soil, water, or air prior to performing calculations 

when any input values are missing. 

Additionally, the user has the option to load a complete set of input data from a previously saved 

file (see Section 2.3). The Load Input From File option is located on the Parameter Input pulldown menu. The loaded site-specific data should provide the model with the necessary 

information to predict PbB levels in children who live on or near the site in question. 

When changing any of the input parameters, the user may enter values with as many as six 

significant figures. In IEUBKwin, three significant figures are reported to the right of the 

decimal point for all output data except blood lead concentration which is reported to one digit to 

the right of the decimal point. However, it should be noted that the true precision of any 

calculated output can be strongly influenced by the least precise input value. An explanation of 

how significant figures are used in IEUBKwin can be found in the Help pull-down menu. 
10 

USER'S GUIDE FOR IEUBKWIN 

Each Parameter Input menu option includes context-sensitive help windows to aid the user. 

These windows are available for most input parameters and are accessed by clicking on the 

<<Help ?>> button. This feature opens a new window which shows the available guidance for 

the subject. In addition, the user has online access to the complete documentation for the model 

under the Help pull down menu. 

Finally, IEUBKwin has been developed to warn the user when she or he has entered 

unacceptable input values. Currently, IEUBKwin contains three classes of error messages that 

will appear when the user enters inappropriate input values. These classes of error messages 

address: 

• Input values that result in greater than 100 percent. In cases where the user enters an 

input value in the form of a percent, the value may not exceed 100 percent. Similarly, 

when percent values are summed, the total may not exceed 100 percent. 

• Negative values. Negative input values are not allowed in IEUBKwin. 

• Valid model inputs. Although the user is permitted to enter any values into the 

IEUBKwin model (given the limits above), in certain instances, the input is limited 

based on scientific evidence (for example, the plausible range of GSD values). 

2.2 DETAILED DESCRIPTIONS OF INPUT OPTIONS 

The following is a discussion of the Parameter Input pull-down menu options for IEUBKwin. 

Help menus and the IEUBK Guidance Manual (U.S. EPA, 1994) provide further assistance and 

discussion on data entry. A detailed list of default values for IEUBKwin model parameters are 

presented in Table 2-1, and the user should refer to the IEUBK Guidance Manual (U.S. EPA, 

1994) for additional information. 

Aside from the mathematical limits described in Section 2.1, there is no limit to the range of 

values permitted in the IEUBKwin model per se. However, empirical validation of the model 

did not address situations where the predicted blood lead concentration exceeds 30 μg/dL; 

therefore, such results must be interpreted with caution (Zaragoza and Hogan, 1998). In 

addition, values for some input parameters are limited by physiology or scientific data as 

discussed in the IEUBK Guidance Manual (U.S. EPA, 1994). Additional information on 

plausible limits for certain parameters is also available from the Input Parameters section of the 

FAQs of the TRW website (http://www.epa.gov/superfund/lead). 
11 

USER'S GUIDE FOR IEUBKWIN 

Table 2–1. Default Values for IEUBKwin Model Parameters 

Parameter Default Value Units 

Indoor air lead concentration (% of outdoor) 30 % 

AIR (by year) 

Air concentration 

Age = 0-1 year (0-11 mo) 

1-2 years (12-23 mo) 

2-3 years (24-35 mo) 

3-4 years (36-47 mo) 

4-5 years (48-59 mo) 

5-6 years (60-71 mo) 

6-7 years (72-84 mo) 

0.10 

0.10 

0.10 

0.10 

0.10 

0.10 

0.10 

μg/m3 

μg/m3 

μg/m3 

μg/m3 

μg/m3 

μg/m3 

μg/m3 

Time outdoors 

Age = 0-1 year (0-11 mo) 

1-2 years (12-23 mo) 

2-3 years (24-35 mo) 

3-7 years (36-84 mo) 

1 

2 

3 

4 

h/day 

h/day 

h/day 

h/day 

Ventilation rate 

Age = 0-1 year (0-11 mo) 

1-2 years (12-23 mo) 

2-3 years (24-35 mo) 

3-4 years (36-47 mo) 

4-5 years (48-59 mo) 

5-6 years (60-71 mo) 

6-7 years (72-84 mo) 

2 

3 

5 

5 

5 

7 

7 

m3

/day 

m3

/day 

m3

/day 

m3

/day 

m3

/day 

m3

/day 

m3

/day 

Lung absorption 32 % 

DATA ENTRY FOR DIET (by year) 

Dietary lead intake 

Age = 0-1 year (0-11 mo) 

1-2 years (12-23 mo) 

2-3 years (24-35 mo) 

3-4 years (36-47 mo) 

4-5 years (48-59 mo) 

5-6 years (60-71 mo) 

6-7 years (72-84 mo) 

2.26 

1.96 

2.13 

2.04 

1.95 

2.05 

2.22 

μg Pb /day 

μg Pb /day 

μg Pb /day 

μg Pb /day 

μg Pb /day 

μg Pb /day 

μg Pb /day 

DATA ENTRY FOR ALTERNATE DIET SOURCES (by food class) 

Concentration: 

home-grown fruits 

home-grown vegetables 

fish from fishing 

game animals from hunting 

0 

0 

0 

0 

μg Pb/g 

μg Pb/g 

μg Pb/g 

μg Pb/g 

Percent of food class: 

home-grown fruits 

home-grown vegetables 

fish from fishing 

game animals from hunting 

0 

0 

0 

0 

% 

% 

% 

% 
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USER'S GUIDE FOR IEUBKWIN 

Table 2–1. Default Values for IEUBKwin Model Parameters 

Parameter Default Value Units 

DATA ENTRY FOR DRINKING WATER 

Lead concentration in drinking water 4 μg/L 

Ingestion rate 

Age = 0-1 year (0-11 mo) 

1-2 years (12-23 mo) 

2-3 years (24-35 mo) 

3-4 years (36-47 mo) 

4-5 years (48-59 mo) 

5-6 years (60-71 mo) 

6-7 years (72-84 mo) 

0.20 

0.50 

0.52 

0.53 

0.55 

0.58 

0.59 

L/day 

L/day 

L/day 

L/day 

L/day 

L/day 

L/day 

DATA ENTRY FOR ALTERNATE DRINKING WATER SOURCES 

Concentration 

first-draw water 

flushed water 

fountain water 

4 

1 

10 

μg/L 

μg/L 

μg/L 

Percentage of total intake 

first-draw water 

flushed water 

fountain water 

50 

100 minus first draw 

and fountain 

15 

% 

% 

DATA ENTRY FOR SOIL/DUST (constant over time) 

Concentration (starting values to be modified using 

appropriate site data) 

soil 

dust 

200 

200 

μg/g 

μg/g 

Soil/dust ingestion weighting factor (percent soil) 45 % 

DATA ENTRY FOR SOIL/DUST INGESTION (by year) 

Soil/Dust ingestion 

Age = 0-1 year (0-11 mo) 

1-2 years (12-23 mo) 

2-3 years (24-35 mo) 

3-4 years (36-47 mo) 

4-5 years (48-59 mo) 

5-6 years (60-71 mo) 

6-7 years (72-84 mo) 

0.085 

0.135 

0.135 

0.135 

0.100 

0.090 

0.085 

g/day 

g/day 

g/day 

g/day 

g/day 

g/day 

g/day 

DATA ENTRY FOR SOIL/DUST MULTIPLE SOURCE ANALYSIS (constant over time) 

Fraction of indoor dust lead attributable to soil 

(MSD) 

Ratio of dust lead concentration to outdoor air lead 

concentration 

0.70 

100 

unitless 

μg Pb/g dust per μg Pb/m3

 air 
13 

USER'S GUIDE FOR IEUBKWIN 

Table 2–1. Default Values for IEUBKwin Model Parameters 

Parameter Default Value Units 

DATA ENTRY FOR SOIL/DUST MULTIPLE SOURCE ANALYSIS WITH 

ALTERNATIVE HOUSEHOLD DUST LEAD SOURCES (constant over time) 

Concentration (starting values to be modified using 

appropriate site data) 

household dust (calculated value) 150 μg/g 

secondary occupational dust 1,200 μg/g 

school dust 200 μg/g 

daycare center dust 200 μg/g 

second home 200 μg/g 

interior lead-based paint 1,200 μg/g 

Percentage 

household dust (calculated value) 100 minus all other % 

secondary occupational dust 0 % 

school dust 0 % 

daycare center dust 0 % 

second home 0 % 

interior lead-based paint 0 % 

BIOAVAILABILITY DATA ENTRY FOR ALL GUT ABSORPTION PATHWAYS 

Total lead absorption (at low intake) 

diet 50 % 

drinking water 50 % 

soil 30 % 

dust 30 % 

alternate source 0 % 

Fraction of total net absorption at low intake rate that 0.2 u nitless 

is attributable to non saturable (passive) processes. 

DATA ENTRY FOR ALTERNATE SOURCES (by year) 

Total lead intake 

Age = 0-1 year (0-11 mo) 0 μg/day 

1-2 years (12-23 mo) 0 μg/day 

2-3 years (24-35 mo) 0 μg/day 

3-4 years (36-47 mo) 0 μg/day 

4-5 years (48-59 mo) 0 μg/day 

5-6 years (60-71 mo) 0 μg/day 

6-7 years (72-84 mo) 0 μg/day 

DATA ENTRY MENU FOR MATERNAL-TO-NEWBORN LEAD EXPOSURE 

Mothers blood lead concentration at childbirth 1.0 μg/dL 

DATA ENTRY MENU FOR PLOTTING AND RISK ESTIMATION 

Geometric standard deviation (GSD) for blood lead 1.6 unitless 

Blood lead level of concern, or cutoff 10 μg/dL 

COMPUTATION OPTIONS 

Iteration time step for numerical integration 4 h 
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USER'S GUIDE FOR IEUBKWIN 

2.2.1 Air Data 

The Air Data option on the Parameter Input pull-down menu opens the Air Data input window. 

Model default values can be replaced with site-specific data for the following parameters: 

• Indoor air Pb concentration as a percentage of outdoor air Pb concentration (μg/m3

) 

• Outdoor air Pb concentration (μg/m3

) 

• Time spent outdoors (hr/day) 

• Ventilation rate (m3

/day) 

• Lung absorption (%) 

The default outdoor air Pb concentration is 0.1 μg/m3

. As a default, the model calculates indoor 

air Pb concentration as 30 percent of the outdoor air Pb concentration. Because the indoor air Pb 

concentration is treated as a fraction of outdoor concentration, the model does not allow a value 

greater than 100 percent to be entered in this field. If the user is working on a site where indoor 

air Pb concentration is in fact greater than the outdoor air Pb concentration, contact the TRW 

(see Section 1.2 for contact information). With the exception of the indoor air Pb concentration, 

the model allows the user to vary the value of each parameter by age. 

2.2.2 Dietary Data 

The Dietary Data input window includes information on that portion of total Pb intake which 

enters the body through the consumption of food. The default daily dietary Pb intake values for 

each age apply to a typical child in the United States. These estimates are derived based upon 

Food and Drug Administration (FDA) food monitoring data collected 1995-2003 (FDA, 2006). 

The model also allows the user to directly alter the dietary lead intake amounts by age. If sitespecific data suggest that default dietary intake rates differ due to the consumption of local 

produce, fish, or game animals, that information may be entered by answering <<YES>> to Use 

Alternate Dietary Values? in the Dietary Data input window. The value in the first column of 

the Dietary Data input window is the observed concentration of Pb in the local food item. The 

second column is the amount of food of a given type obtained from local sources, as a percent of 

total consumption of that food type. Alternate dietary data should not be used in combination 

with changes to default age-specific lead intake data. Local fish and game animal meat are part 

of the same “meat” category, and the percentage values for this food category may not be greater 

than 100. Home grown fruits and home grown vegetables are part of the “fruit and vegetable” 

category. Limitations on inputs for the “meat” or the “fruit and vegetable” category are 

explained in the <<?>> button for each input parameter. Additional guidance is available from 

the FAQs of the TRW website (http://www.epa.gov/superfund/lead). 
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USER'S GUIDE FOR IEUBKWIN 

2.2.3 Drinking Water Data 

The Drinking Water Data input window is divided into two sections: water consumption rates 

and environmental concentrations. The default consumption rates are age-dependent and based 

on national averages. These consumption rates should be changed only when valid site-specific 

monitoring data is available. When entering a water Pb concentration, the user has two options: 

either use one concentration for all water sources (Option 1), or use source-dependent values 

(Option 2). Option 1 is selected by answering <<NO>> to Use Alternate Water Values? If the 

user elects Option 1, the user can either select the default value (4 μg/L) or change the water Pb 

default concentration to reflect conditions at the site. Option 2 is selected by answering 

<<YES>> to the Use Alternate Water Values? By selecting Option 2, the user can enter sitespecific values for the following parameters: 

• Percentage of total consumed as first draw (%) [default=50%] 

• Concentration of lead in first draw (μg/L) [default=4 μg/L] 

• Concentration of lead in flushed (μg/L) [default=1 μg/L] 

• Percentage of total consumed from fountains (%) [default=15%] 

• Concentration of lead in fountain water (μg/L) [default=10 μg/L] 

Note that total water consumed is the sum of first draw, flushed, and fountain water. 

2.2.4 Soil/Dust Data 

Because soil and dust are often the primary sources of Pb exposure at a site, the Soil/Dust Data 

menu option is the most detailed and complex of the input windows. The first parameter that can 

be modified by the user is the Soil/Dust Ingestion Weighting Factor. This value represents the 

percentage of total soil/dust ingestion that is derived from soil and the percent that is derived 

from dust. The value in the parameter input window of the model is the percent from soil. The 

combined soil/dust ingestion weighting factor equals 100 percent. 

• The Soil/Dust Data input window allows the user to adjust the rate at which a child 

ingests soil and dust. These values should only be adjusted if site-specific, technicallysupportable data that are applicable to this parameter are available. The user should 

consult the Ingestion Rate short sheet that is available on the TRW website for further 

information concerning the use of site-specific soil ingestion values. (See Appendix C or 

[Short Sheet: IEUBK Model Soil/Dust Ingestion Rates, EPA #540-F-00-007, OSWER 

#9285.7-33, December 1999] http://www.epa.gov/superfund/lead) 

2.2.4.1 Lead in Soil 

When site-specific soil values are used, the TRW recommends replacing the default constant 

dust value (200 μg/g) with valid site-specific data. At a minimum, soil concentration data is 

needed to obtain modeling results that are predictive of site risks. If no valid site-specific dust 

data are available, it is strongly recommended that user use the Multiple Source Analysis (MSA) 
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USER'S GUIDE FOR IEUBKWIN 

option to estimate dust lead concentrations as a function of soil lead concentrations. This 

approach presumes, however, that there are not significant indoor sources of lead dust, i.e., 

deteriorating lead-based paint. 

When specifying a concentration of Pb in soil, the user has the following two options: 

• Use an alternate site-specific constant value in place of the default value (200 μg/g). 

When the user inputs a constant value for soil (or dust), the value is applied to all age 

ranges. The 200 μg/g value, while serving as a plausible value for many urban 

settings, is not intended to be a substitute for site data. 

• Use the Variable Values option to change the concentration of soil to which children 

are exposed by age. If the user chooses to enter a value instead of using the model 

default or a site-specific constant value across all age ranges, the user must select the 

Variable Values option and enter the new value into each age field. 

2.2.4.2 Lead in Dust 

By default, the IEUBK model defaults to Multiple Source Analysis because it assumes that sitespecific dust concentrations are not measured and therefore, Multiple Source Analysis should be 

used to determine the appropriate dust concentration. If site-specific dust measurements are 

available, this information can be entered as a Constant Value or Variable Values (by age) before 

running the model by selecting the appropriate mode in the soil dust input window. 

When specifying a concentration of Pb in dust, the user has the following three options: 

• Use an alternate site-specific constant value in place of the default value (200 μg/g). 

• Use the Variable Values option to change the concentration of dust that children are 

exposed to by age. If the user chooses to enter variable values instead of using the 

model default or a site-specific constant value, the user must select the Variable 

Values option and enter the new value into each age field. 

• Use Multiple Source Analysis for dust concentrations. Multiple Source Analysis 

allows the use of information about the contribution of soil lead (PbS), air Pb, and 

other sources to derive a value for indoor dust lead (PbD). The data entry line in 

Multiple Source Analysis represents the contribution of Pb in soil to the concentration 

of Pb in indoor dust. If there were no other sources to contribute to indoor PbD (such 

as lead-based paint), this would be the ratio of the PbD concentration to the PbS 

concentration. As indicated in the IEUBK Guidance Manual (U.S. EPA, 1994), the 

default value of 0.70 is appropriate to neighborhoods or residences in which soil 

materials are available for contact and track-in into the house. In the absence of 

indoor sources of lead of established significance, the TRW recommends that the soil 

contribution to dust lead be evaluated by comparing the average or arithmetic mean 

of soil lead concentrations from a representative area in the child's yard, and an 

average of dust lead concentrations from representative areas frequented by children 
17 

USER'S GUIDE FOR IEUBKWIN 

inside the house. There are complicated statistical and practical matters involved in 

evaluating this parameter. See the TRW short sheet on MSD, available from the 

TRW website. (See Appendix C or [Short Sheet: IEUBK Model Mass Fraction of 

Soil in Indoor Dust (MSD) Variable, EPA #540-F-00-008, OSWER #9285.7-34, June 

1998] http://www.epa.gov/superfund/lead). 

The second data entry line is the contribution to indoor dust from the deposition of airborne Pb, 

over and above the PbS contribution. The current default value is an additive increment of 

100 μg/g Pb in house dust for each μg Pb/m3

 air. 

The final set of inputs allows the user to consider additional sources of indoor dust by entering 

data into the Indoor Dust Lead Sources portion of the MSA screen. The user has the option to 

enter a concentration and the fraction of dust intake to baseline indoor dust; secondary 

occupational dust; dust at school, daycare or second home; and the exposure to Pb in dust from 

household paint measured as a percentage of total dust ingestion and concentration. 

The sum of all these alternate source percentages may not be greater than 100. The model will 

automatically adjust the indoor dust percentage so that the sum of all sources is 100. When all 

the alternate source data have been entered, the model will calculate the Multiple Source Average 

concentration and display it in the Soil/Dust Data window. 

2.2.5 Maternal Data 

The Maternal Data input window, on the Parameter Input pull-down menu, allows the user to 

consider the impact of Pb transferred from the mother to the fetus in utero. The Pb that is stored 

in the tissues of the newborn child is calculated by entering the maternal PbB value at the time of 

delivery (default = 1.0 μg/dL). The empirical validation effort for the IEUBK model did not 

include data specific to the disposition of maternally supplied lead in a young child, and model 

predictions in this regard should be interpreted with caution. 

2.2.6 Alternate Source Data 

The Alternate Source Data input window, on the Parameter Input pull-down menu, allows the 

user to input Pb concentrations from sources that are not covered under other menus in the 

model. Examples include the direct ingestion of lead-based paint and the use of cosmetics or 

home remedies. In cases where alternate sources exist, the intake of Pb (μg/day) must be 

calculated from the site-specific data available. If the alternate source is lead-based paint, this 

exposure is in addition to exposure to lead-based paint in house dust, which is covered in the 

Multiple Source Analysis input window on the Soil/Dust Data option. If values are entered in the 

Alternate Source Data input window, then the Total Percent Accessible for Alternate must be 

changed in the GI/Bioavailability input window on the Parameter Input pull-down menu (see 

Section 2.2.7). 
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USER'S GUIDE FOR IEUBKWIN 

Building an exposure scenario using the Alternate Source Data should be done with care. The 

model assumes all entries represent chronic exposure. Remember that the model’s output 

represents only those children defined by the exposure scenario. 

2.2.7 GI Values/Bioavailability 

The GI Values/Bioavailability option on the Parameter Input pull-down menu allows the user to 

make adjustments to the gastrointestinal absorption coefficient to account for site-specific 

information on bioavailability. If this option is selected, a disclaimer window appears which 

indicates that the user should only change default values if alternative bioavailability information 

is available. Relative bioavailability is indexed by measuring the bioavailability of a particular 

substance relative to the bioavailability of a standardized reference material, such as soluble lead 

acetate. For the IEUBK model, soluble lead in water and food is estimated to have 50 percent 

absolute bioavailability based on the bioavailability of soluble lead acetate. 

Relative bioavailability is indexed by measuring the bioavailability of a particular substance 

relative to the bioavailability of a standardized reference material, such as soluble lead acetate. 

For the IEUBK model, soluble lead in water and food is estimated to have 50 percent absolute 

bioavailability based on the bioavailability of soluble lead acetate. Furthermore, qualitative 

estimates of relative bioavailability can be made in the uncertainty section of a risk assessment. 

After selecting «OK», the GI Values/Bioavailability Information input window appears. The 

TRW recommends not changing the bioavailability default without a thorough understanding of 

the absorption methodology. Additional guidance on bioavailability is available from the TRW 

website. (See Appendix C or [Short Sheet: IEUBK Model Bioavailability Variable, EPA #540-

F-00-006, OSWER #9285.7-32] http://www.epa.gov/superfund/lead). 

2.2.8 Geometric Standard Deviation (GSD) 

Geometric Standard Deviation (GSD) is a measure of the relative variability in PbB of a child of 

a specified age, or children from a hypothetical population whose Pb exposures are known. The 

GSD in IEUBKwin encompasses biological and behavioral differences, measurement variability 

from repeat sampling, variability as a result of sample locations, and analytical variability. The 

default value of 1.6 is recommended. This GSD value is based on specific analyses of data from 

several neighborhoods with paired data for environmental Pb concentration and measured PbB 

levels. The TRW recommends that site-specific estimates of GSD not be substituted for the 

default value without detailed, scientifically defensible studies documenting site-specific 

differences in child behavior or Pb kinetics. Should the user decide to modify the GSD, 

IEUBKwin currently accepts values within the range of 1.3 to 1.8 for the GSD based on results 

of site-specific data. If the user enters values outside of this range, a warning screen will appear 

telling the user to select a different value. A GSD short sheet is currently under development and 

will be available at the TRW website upon completion. Additional guidance is available through 

the FAQ How can I derive a site-specific geometric standard deviation (GSD)? on the TRW 

website (http://www.epa.gov/superfund/lead). 
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USER'S GUIDE FOR IEUBKWIN 

2.3 SAVE AND LOAD INPUT PARAMETERS 

If the user wishes to retain the current set of model input parameters (media concentrations, 

intake rates, and bioavailability values) as the starting point for another analysis, the data can be 

saved using the «Save Input to File» command on the Parameter Input pull-down menu. The 

user may create a filename (eight characters or shorter), which will be stored in the form 

[NAME].svd. It should be noted that, the IEUBKwin model has a 16-bit dynamic library, and is 

not a full 32-bit application, and therefore does not support long filenames. The model also uses 

a directory structure such that the user may specify the location of the saved input file; by default 

the model will save the input file in the IEUBKwin subfolder under the Programs directory 

which is where all file types (i.e., input files, results files) are stored unless otherwise specified 

by the user. Saved parameter data can be loaded using the «Load Input from a File» command 

found on the Parameter Input pull-down menu. It should be noted that, if the user loads a saved 

text input file, the same checks will be performed by the model to determine the appropriateness 

of the input values as when the user enters input values from the model input modules. The 

model does not read tab or comma-delimited batch mode files. 
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USER'S GUIDE FOR IEUBKWIN 

3.0 Model Analysis 

This section describes the types of analyses that can be run with IEUBKwin. Further discussion 

can be found in the IEUBK Guidance Manual (U.S. EPA, 1994). 

3.1 OPTIONS FOR MODEL ANALYSES 

Effective use of IEUBKwin requires entering data that are appropriate to the site(s), 

parameter(s), and subject(s). The most convenient way to accomplish this is to construct a multimedia, site-specific exposure scenario. The user should be aware that a site-specific risk 

assessment requires site-specific soil concentrations which may be augmented by site-specific 

data for dust, air, food, and other adjustable defaults. 

The use of site-specific data is recommended to tailor the exposure to the conditions at the site. 

Site-specific data are most commonly used in place of the model default values for Pb 

concentrations in soil, dust, air, and water. Site-specific data for locally caught fish or homegrown vegetables are sometimes used to augment dietary default values. However, such data 

should be evaluated for validity prior to use. Model default values should only be replaced when 

site-specific data specific to the parameters are more representative. IEUBKwin default values 

should never be adjusted simply to attain a better match between modeled and empirical PbB 

concentrations. 

Prior to using IEUBKwin to calculate PbB levels, the user should decide what type of analysis 

should be run: single simulation run, multiple simulation run, or batch mode. Each of these is 

appropriate for certain scenarios, and inappropriate for others. A single simulation allows the 

user to run scenarios for a single location, or multiple locations with homogenous media 

concentrations (Categories A and B of Figure 2-1, Section 2.0). By contrast, multiple runs allow 

the user to specify a range Pb concentrations for a specific environmental media and obtain 

results of model runs at multiple points within that range. Batch mode allows the user to run 

input data for many locations having different media concentrations in a single run of the model. 

Additionally, batch mode allows the use of different ages or different values for Pb concentration 

in soil, dust, water, air, and alternate Pb sources for each exposure scenario. The media intake 

and absorption parameters are the same for every exposure scenario in a batch mode run and 

must be specified before using the Run Batch Mode Model option, unless default values are used. 

Output options for results from Single, Multiple, and Batch Mode runs are presented below. 

3.2 OVERVIEW OF MODEL OUTPUT 

IEUBKwin can calculate four primary outputs: 

• Geometric mean PbB levels, by age 

• Percent of children with PbB in excess of a user-specified level of concern (typically 

10 μg/dL) 

• Average media-specific daily Pb uptake rates 

• Media-specific remediation goals 
21 

USER'S GUIDE FOR IEUBKWIN 

The output data can be saved and presented in tables, graphs, or text files. By default, the model 

will generate a text file of the output unless otherwise specified by the user prior to running the 

model. Screen captures of graphs (for use in technical reports) can be performed by applying the 

Print Screen feature available on most PC keyboards, re-sizing the image to the appropriate 

dimensions, and exporting the image to the desired application (e.g., Corel WordPerfect or 

Microsoft Word). While printed tables and graphs allow convenient documentation of 

IEUBKwin results in risk assessments, text files can also be exported to most statistical software 

packages for additional analysis. The appropriate procedures to follow when exporting output 

data to Lotus 1-2-3 or Microsoft Excel are described in Appendix A. 

3.3 SELECTING OUTPUT ALTERNATIVES 

Results of IEUBKwin simulations may be saved in several forms. The user should select the 

most useful forms in advance, because the results of some interactive simulations cannot be 

recovered without repeating the analysis once the user has bypassed the opportunity to save the 

results. 

3.3.1 What Graphical Options are Included in IEUBKwin? 

IEUBKwin incorporates some output options that facilitate presentation risk assessment results. 

The graphical output choices in the IEUBKwin Graph pull-down menu include the following 

choices: 

• PbB concentration vs. media Pb concentration 

• Distribution probability percent 

• Distribution probability density 

• Distribution probability for multiple runs 

• Probability density for multiple runs 

Some plots may be used for single runs, while others are applicable for multiple runs. These 

plots present estimates of a plausible distribution of PbB levels that are centered on the 

calculated geometric mean blood lead. To derive the distribution around the geometric mean, 

IEUBKwin uses a geometric standard deviation–a value describing the spread around the 

geometric mean PbB. From this distribution, IEUBKwin calculates the probability that a child’s 

PbB will exceed a user-selected PbB level of concern (typically 10 μg/dL) according to the 

equation z = (ln(10) - ln(GM)/ln(GSD). For more information see Appendix B. 

As discussed above, the GSD is a measure of relative variability in PbB levels of children of a 

specific age or a hypothetical population of children whose Pb exposure is known. The GSD in 

IEUBKwin encompasses biological and behavioral differences, measurement variability from 

repeat sampling, variability as a result of sample locations, and analytical variability. The 

default value of 1.6 is recommended. Figure 3-1 illustrates the impact of the relative positions of 

the level of concern (LOC) and the geometric mean (GM) on the proportion of children “at risk” 

for two populations with different GSDs. If LOC>GM, then the area for children at risk (shaded 

plus solid) for GSD=1.7 is greater than the area (solid) for GSD=1.4. In situations where the 
22 

USER'S GUIDE FOR IEUBKWIN 

typical GM blood lead concentrations are predicted to be higher than the LOC, the graph would 

look different. 

GSD = 1.4 

GSD = 1.7 

Children 

not at 

risk 

Children at risk 

LOC GM LOC 

Figure 3-1. The Impact of GSD on Plausible Geometric Mean PbB Distributions. 

If LOC<GSD, then the area for children not at risk (shaded plus solid in lower tail) for GSD=1.7 

is larger than the area for children not at risk (solid in lower tail) for GSD=1.4. While this might 

at first appear to suggest that risks are lower in this case with a higher GSD, the user should note 

that the graph with the high GSD also indicates an increased risk of even higher blood lead levels 

at values in excess of the LOC. Both distributions presented in the figure are based on the same 

data set. 

3.4 COMPUTATION OPTIONS 

3.4.1 Run a Single Simulation 

This option uses only the currently loaded parameter set (the default values and site-specific data 

specified by the user). After the user selects Run the Model (Single Run) from the Computation 

pull-down menu, the model prompts the user to choose a time step for numerical iteration. This 

is a technical matter which does not usually need to be changed from the default. The default 

time step is 4 hours. The time step does not determine the averaging time used to define average 

daily intakes of lead. The time step is used in the biokinetic component of the model in 
23 

USER'S GUIDE FOR IEUBKWIN 

combination with compartmental transfer times to calculate the distribution of lead among bodily 

tissues. 

If you want to save the results for reference or further analysis, the user can assign a unique file 

name, otherwise the default file name will be assigned. If you want to analyze the data using a 

spreadsheet, checking this box will save the data in a tab-delimited format for import into a 

statistical software package or spreadsheet program (see details in Appendix A). 

3.4.1.1 Single-Run Options 

Single-run plotting options in IEUBKwin include the following: 

• The average of the geometric mean PbB concentrations for children in sequential 1-

year age intervals, the input concentrations for several media, and the media-specific 

daily Pb uptake for each year are saved internally. The output file that is automatically 

generated is RunModel.txt. 

• Plotting the cumulative probability distribution for exceeding any user-specified PbB 

level of concern for a single exposure scenario (Option 2—Distribution Probability 

Percent). This is sometimes called the exceedance probability distribution. 

• Plotting the log-normal probability density function of PbB levels for a single 

exposure scenario predicting geometric mean PbB (Option 3—Distribution 

Probability Density). 

The probability density function gives users a better idea of the spread of PbB levels for children 

exposed to a single set of environmental Pb concentrations. The plot of the exceedance 

probability distribution also shows the fraction of children above a PbB level of concern for the 

single-exposure case (e.g., what fractions of children are above 10 μg/dL). The user may print 

the probability plots after viewing. The single-run media plots are saved as [name].GRF. If 

saved, these graphs may be viewed at a later date using the Graph pull down menu. 

3.4.2 Calculating a Blood Lead Concentration Associated with Media-Specific 

Concentration 

The user may select Find Blood Pb Concentration from the Computation pull-down menu and 

enter a known media lead concentration to determine the predicted concentration of lead in blood 

associated with that media concentration. 

This module generates a plot of the relationship between blood lead concentration and the 

exposure to lead in a specific, user-selected, environmental medium (e.g., soil, dust, drinking 

water, air, or diet). The module can be used to explore the sensitivity of the predicted blood lead 

concentration to assumptions about exposures to lead in specific media. The module can also be 

used to explore the sensitivity to other exposure assumptions. For example, the effect of 
24 

USER'S GUIDE FOR IEUBKWIN 

alternative assumptions regarding the soil lead absorption fraction can be explored by comparing 

plots of blood lead concentration vs soil lead concentration, when different values for the lead 

absorption fraction are assumed. 

3.4.3 Run Multiple Simulations 

This option uses the currently loaded parameter set (default values and site-specific data 

specified by the user) but repeats the run for either a range of concentrations for a user-specified 

medium. To conduct this simulation run, select the medium, the range of values for that 

medium, and the number of time steps for numerical iteration. With Multiple Runs the user can 

determine PbB concentration by age group based on a range of media Pb concentrations and can 

search for the medium Pb concentration associated with an age-specified PbB concentration. 

3.4.3.1 Multiple-Run Options 

IEUBKwin has additional features that allow the user to combine output from several runs onto 

single plots. These multiple-run options include both blood lead concentration vs. media lead 

concentration plots and a sequence of graphics-overlay simulation runs (multiple runs) as 

described below. For both of these options, the media range option saves input data for 

geometric mean PbB vs. media Pb plots for a range of evenly spaced media Pb concentrations. 

For example, the user may generate plots of PbB vs. PbS concentrations smoothly interpolated 

from calculated values at 250, 500, 750, and 1,000 μg/g for children aged 12 to 24 months. 

Results are saved as filename [name].LIN. The data in the [name].LAY overlay file include the 

geometric mean PbB for children in the age range, and the Pb concentration in soil and other 

media. The actual plots of probability density or cumulative distribution functions depend on the 

GSD value selected for use in risk estimates, and these plots can be printed. While this option is 

useful in recognizing the pattern between increasing media concentrations and increasing blood 

lead levels, the results are not intended to directly support risk-based decisions. These graphs 

show the predicted geometric mean blood lead levels, and not the probability of exceeding 

10 μg/dL as a risk criterion in EPA's risk management guidance for lead. 

• Geometric mean blood lead concentration vs. media lead concentration graph, where 

each run increases the Pb concentration in a specified medium by a user-defined 

amount across a range (Option 1—Distribution Probability for Multiple Runs). 

• Overlaid plots of the cumulative exceedance probability distributions of PbB levels 

for multiple media concentrations, where each run increases the Pb concentration in a 

specified medium by a user-defined amount (Option 4—Distribution Probability for 

Multiple Runs). 

• Overlaid plots of the log-normal probability density functions of PbB levels for 

multiple exposure scenarios, where each run increases the Pb concentration in a 

specified medium by a user-defined amount (Option 5—Probability Density for 

Multiple Runs). 
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USER'S GUIDE FOR IEUBKWIN 

Overlaid plots cannot be used unless the user has previously created an output file from the 

Computation menu, with the file extension *.LAY. The overlaid probability density functions 

give most users a better idea of how the probability of exceeding a PbB level of concern 

increases with each incremental increase in environmental lead. The exceedance probability 

distributions may be used to estimate the increases in the fraction of elevated PbB levels or to 

visually estimate the environmental Pb levels corresponding to a specified fraction of 

unprotected children above the level of concern. 

3.4.4 Run Batch Mode Simulation 

The input data file for a batch run must be created outside of IEUBKwin using any text editor 

(e.g., Notepad). The following conventions must be observed in creating the batch file: 

• The input data file must be an ASCII file with no special characters. The model does 

not read tab or comma-delimited batch mode files. 

• The data set must have a DAT extension (i.e., [name].dat). 

• The first three lines of the input data file can be any identifiers that the user may 

require; usually the first line is the run name, the second line is the modeling options 

used in the run, and the third line consists of the headers for variables in the data set. 

• The data fields are entered format-free, although the use of regular spacing and 

alignment of decimal points are recommended to improve readability. 

• The maximum width is 8 spaces per column. 

• The variable values should be separated by spaces. 

• For quicker runs, the recommended limit is 500 rows of data. 

• The missing values must be shown by a single decimal point. 

• Each line in the input data file must contain data or blank values for missing data for 

the following 10 variables: 

1. Child identifier code 6. PbD concentration in μg/g 

2. Family or residence unit identifier code 7. Drinking water Pb concentration in μg/L* 

3. Area or neighborhood identifier code 8. Air Pb concentration in μg/m3

* 

4. Child’s age in months 9. Daily intake of Pb from “alternate” 

5. PbS concentration in μg/g sources in μg Pb/g 

10. Observed child PbB level in μg/dL*

Any of these (*) may be left blank by just placing a period in the middle of the data column. 

There is no need for PbB values, since the model can calculate risk for a group of locations or 
26 

USER'S GUIDE FOR IEUBKWIN 

residences. For many users the easiest way to create a batch mode input file is to use a 

spreadsheet (see Appendix A). As noted above, the child’s age (in months) must be entered. 

The media concentrations for water and air from the parameter input windows will be entered if 

values for these media are missing. Either a PbS concentration or a PbD value is needed for the 

simulation, along with a stand-in value (imputation rule) if one is missing (e.g., if the user does 

not fill in PbD values, the current default is to replace a missing PbD concentration with the PbS 

concentration). The user may prefer to create an input data file with missing PbD concentrations 

replaced by some fraction of the PbS concentration. 

Note that IEUBKwin considers only two significant digits (to the right of the decimal point) 

from the data input file for running batch mode; however, the model uses double precision (eight 

digits) in all its calculations. In the current stand alone version, IEUBKwin is not capable of 

executing consecutive batch mode files from a list of files. 

The batch mode option can be used to develop estimates for statistical analyses of simulated 

community PbB distributions with or without observed PbB levels. When PbB data are 

available, batch mode also provides a tool for developing empirical comparisons of the model 

predictions and measured blood lead concentrations. 

Output consists of files [name].TXT that contain predicted PbB concentrations for each case or 

record (child) in the input data file. The output files also document the missing value 

imputations when some of the input data on residential media Pb concentrations are missing. 

The files may be used as input for statistical analysis in other software programs (see 

Appendix A). 

A feature that is new to the 32-bit version allows for processing of multiple batch mode input 

files. The Batch Run Dialog includes a list box, which will list the batch input data files 

available for processing. The user may add or remove files from the queue. The results are 

written to a single file BATCHRUN.TXT (unless another file name is specified). Each input file 

is processed sequentially, and the results appended to the results file below the previous run. 

Results are identified by repeating the header, which identifies the input file name. 

Additional guidance on Batch Mode inputs and use is available in the FAQs on the TRW 

website. (http://www.epa.gov/superfund/lead) 
27 

USER'S GUIDE FOR IEUBKWIN 

4.0 Interpretation of Results 

4.1 UNDERSTANDING THE OUTPUT 

Each of the output options described above allows the user to examine a different aspect of 

IEUBKwin simulation. The output from a single simulation run may be displayed in several 

forms. Most users wish to see the variability associated with a predicted PbB concentration. This 

range can be demonstrated graphically by selecting the intrinsic variability GSD, and then 

plotting a cumulative probability distribution. The range of plausible PbB values may be 

determined graphically as defined by upper and lower percentiles of the distribution. For 

example, the 5th and 95th percentiles of the distribution will include 90 percent of the children 

with the given site-specific or household-specific exposure scenario. Note that the plausible 

range reflects predicted variability among individuals with the same exposure scenario, and 

should not be confused with a statistical confidence limit (which is a measure of statistical 

uncertainty in a predicted value such as a geometric mean). 

The other output characteristic that many users wish to see is the estimated probability of 

exceeding the specified PbB level of concern, corresponding to the given exposure scenario or 

scenarios (for multiple runs in a given medium). According to the IEUBK Guidance Manual 

(U.S. EPA, 1994), there are two valid interpretations for this output: 

1. The output of the model may be considered to be the best estimate of a plausible 

range of PbB concentrations for a hypothetical child under a specific Pb exposure 

scenario. The range of values is centered on the geometric mean PbB concentration 

expected for a typical child with this exposure scenario. The portion of the upper tail 

of the probability distribution exceeding some chosen PbB level of concern provides 

an estimate of the risk of exceeding that level for a typical child of that age residing in 

the same household and with the same exposure history. 

2. The output of the model may also be considered to be the predicted geometric mean 

PbB of a population of children under the same Pb exposure scenario. That portion 

of the upper tail that exceeds some chosen PbB level of concern indicates the fraction 

of the population exceeding that level when all of these children have the same 

exposure history. 

A common misinterpretation of IEUBKwin is that it predicts community geometric mean PbB 

and the fraction of the population of children at risk when the input is the mean or geometric 

mean of household-specific environmental Pb concentrations. That misinterpretation arises, 

particularly when the environmental variables have a wide distribution among the neighborhoods 

of the community. A correct approach requires applying the model to each individual home (or 

area with homogeneous lead concentrations) and combining these results as an aggregate to form 

an estimate of neighborhood or community risk. 

It should be noted that the user may experience some discrepancies in the appearance of the 

graphs produced with IEUBKwin as a result of the limitations of Visual Basic C++, the 
28 

USER'S GUIDE FOR IEUBKWIN 

programming tool used to develop the model. Specifically, scientific notation is used for values 

less than 0.01 (e.g., 10-2) on graphical outputs; however, improper formatting of the scientific 

notation occurs as a result of the Visual Basic C++ programming functions and cannot be 

corrected. This discrepancy should be eliminated in future versions of the model, and currently 

does not functionally impede upon the user’s ability to read and interpret graphs. 

The National Contingency Plan2 states that the Superfund process for establishing cleanup 

numbers for contaminated sites consider nine criteria concerning risks associated with remedial 

alternatives analysis that apply to. The nine criteria are as follows: 

 Prim ary Criteria 

1. Overall protection of human health and the environment 

2. Compliance with applicable or relevant and appropriate standards, limitations, 

criteria, and requirements (ARARs) 

 Balancing Criteria 

3. Long-term effectiveness and permanence 

4. Reduction of toxicity, mobility and volume

 5. Short-term effectiveness 

6. Implementability 

7. Cost 

 Modifying Criteria 

8. State acceptance 

9. Community acceptance 

2

For more information, see 40CFR §300.430. 
29 

USER'S GUIDE FOR IEUBKWIN 

5.0 Model Application and Documentation 

The output of IEUBKwin helps users develop an understanding of the potential risk for elevated 

PbB levels in children. Through different model run scenarios, these potential risks can be 

calculated for a number of different hypothetical situations, including risks for a single child, a 

group of neighborhood children, or an entire community. With proper application and 

documentation, IEUBKwin can effectively and accurately predict the risks at lead-contaminated 

sites. 

5.1 MODEL APPLICATION 

IEUBKwin is designed to facilitate two processes: rapid delineation of the relationship between 

environmental Pb and PbB in children and calculation of their risk of elevated PbB (i.e., the 

probability that a given child or group of children will have PbB concentrations exceeding a 

specified level of concern). As such, IEUBKwin provides a tool for site-specific risk assessment 

for young children exposed to Pb from different media and through different pathways in their 

environment. The intended applications of IEUBKwin are to: 

• Provide a summary of children’s long-term, primary residential exposure to lead. 

• Provide a best estimate of the geometric mean PbB concentration for a typical child, 

aged 6 months to 84 months, assumed to reside at a given residence. 

• Provide a basis for estimating the risk of elevated PbB (i.e., for exceeding a 

designated PbB concentration of concern) for a hypothetical child of specified age 

with a given site-specific residential Pb exposure. 

• Provide a basis for estimating the risk of elevated PbB concentrations among 

populations of children under age 7 in a given neighborhood by aggregating the 

individual residential risk estimates. 

• Predict likely changes in risk of elevated PbB concentrations from exposure to soil, 

dust, water, or air Pb following abatement actions designed to reduce exposure levels 

from one or more environmental media. 

• Provide assistance in determining appropriate soil or dust Pb target cleanup levels at 

specific residential sites. 

• Provide assistance in estimating PbB concentrations associated with soil or dust Pb 

concentrations at undeveloped residential sites that may be developed in the future. 

EPA has established default values for all of the user-specified parameters in IEUBKwin. Use of 

the default parameters is recommended unless valid site-specific monitoring data exist to define 

values that are higher or lower. Site-specific data are commonly used in place of the model 

default values for Pb concentrations in soil, dust, air, and water. However, for intake rates, 
30 

USER'S GUIDE FOR IEUBKWIN 

bioavailability and PbB distribution parameters, the TRW recommends that the default values be 

used, unless accompanied by strong evidence supporting the use of site-specific values. Model 

default values should never be adjusted simply to attain a better match between modeled and 

empirical blood lead. Information on situations where it might not be advisable to use the 

IEUBK model can be found in the IEUBK Guidance Manual (U.S. EPA, 1994) and Section 2.0 

of this manual. 

5.2 MODEL DOCUMENTATION (MINIMUM REQUIREMENTS) 

By reviewing every adjustable parameter in the model and noting which ones have been 

modified in a particular run, the user has a permanent record of the input. The data used in the 

model runs should be saved so the results can be reproduced. Different levels of documentation 

are required for specific applications of the model. The text of risk assessments should contain a 

full discussion describing the inputs, use, and outputs of the model. Any model output 

referenced should be included in appendices of the risk assessment, including distribution and 

density curves, text outputs, and batch mode files. A listing of model inputs should be included 

in the text or as an appendix to the risk assessment. IEUBKwin captures data and comments in 

the risk assessment mode in a tabular format. This information can be exported to a spreadsheet 

application (e.g., Lotus 1-2-3, Microsoft Excel) for submission to EPA (see Appendix A). 

5.3 USER RESPONSIBILITIES 

The user is responsible for using model input parameters that are appropriate to the site. 

Generally the minimum site-specific data collection and analyses include, but are not necessarily 

limited to, collection of an adequate number of representative soil and dust samples, and 

determination of the Pb concentrations and physical or chemical properties that affect transport 

and bioavailability. The typical input data include a multimedia household environmental Pb 

study that includes soil, dust, paint, water, and air; information on Pb exposures outside a child’s 

home; information on family demographics and child behavior patterns in the community that 

may affect access to Pb sources; and characterization of physical and chemical properties that 

affect bioaccessibility and bioavailability. 
31 

USER'S GUIDE FOR IEUBKWIN 

6.0 Example Scenarios 

This section presents examples and results obtained from reasonably straight-forward 

applications of IEUBKwin. The first part of this section presents results obtained for single runs 

of the model, when only soil, dust, and water lead concentrations are entered into the model. 

Additional examples cover the sum of the individual risks approach, and the assessment of risk 

using grouped data for a neighborhood. These examples are relatively simple and are intended to 

cover the most common applications of IEUBKwin. Several additional examples, some more 

complex in nature, are presented for the user in the IEUBK Guidance Manual (U.S. EPA, 1994). 

6.1 SIMPLE CASE SINGLE RUNS 

If the model is run using the following inputs, the user should calculate the following outputs for 

children aged 0 to 84 months. These data can be used as a quick test of the model. 

Table 6–1. Simple Case Runs 

Input Parameters Output Parameters 

Soil Dust Water Age All other Geometric % Above 

(mg/kg) (mg/kg) (μg/L) (months) inputs mean (μg/dL) 10 μg/dL 

Run 1 Default Defa ult Default 0-84 Default 2. 7 0.287 

Run 2 500 500 Default 0-84 Default 6.0 13.899 

Run 3 500 500 50 0-84 Default 8.8 39.572 

Run 4 1,000 1,000 Default 0-84 Default 10.2 51.496 

Run 5 1,000 1,000 50 0-84 Default 12.6 68.553 

6.2 “SUM OF INDIVIDUAL RISKS” APPROACH 

Suppose that there are data on four households with children in a neighborhood. Residents of 

each household are exposed to lead-contaminated soil. The first house has 250 μg/g Pb in soil, 

the second house has 250 μg/g, the third house has 1,000 μg/g, and the fourth house has 

1,000 μg/g. Dust lead (PbD) concentrations are assumed to be 70 percent of the PbS 

concentration in houses 2 and 4, and 15 percent of the PbS concentration in houses 1 and 3. As 

an estimate of air Pb contribution to PbD at 0.1 μg Pb/m3

, 10 μg/g was added to PbD. The 

respective PbD concentrations are 47.5 μg/g, 185 μg/g, 160 μg/g, and 710 μg/g. All other 

parameters are set to default values. 

The samples are assumed to be representative of the exposure distribution in the neighborhood. 

The selection of four houses is for illustration purposes only. The risk estimates are intended to 

be unbiased estimates of potential risk for other years in which different children, not in the 

current sample, may occupy the same or other houses in the neighborhood. Obviously, a reliable 
32 

USER'S GUIDE FOR IEUBKWIN 

estimate of neighborhood risk will require more than four houses. The probability density of 

PbB for the four houses is shown in Figure 6-1 and the interpreted results in Table 6-2. 

House 4 

House 3 

House 2 

House 1 

0.4 

0.3 

0.2 

0.1 

0.0 0 5 10 15 20 25

Blood Lead,:g/dL

Figure 6-1. Hypothetical Probability Density of Blood Lead in Houses 1 to 4. 
33 

USER'S GUIDE FOR IEUBKWIN 

Table 6–2. Interpreted Results for Figure 6–1 

House 

number 

PbS concentration 

(μg/g) 

PbD concentration 

(μg/g) 

Probability of exceeding 

10 μg/dL 

1 250 47.5a 0. 106 

2 250 185b

 0. 736 

3 1,000 160a

 1 6.729 

4 1,000 710b

 4 0.534 

Risk from all houses 1-4 58.105 

a

 Calculated using multiple source analysis and an MSD of 0.15 b

 Calculated using multiple source analysis and an MSD of 0.70 

The sum of the risks for these four houses 0.106% + 0.736% + 16.729% + 40.534% = 58.105%. 

That is, 0.581 children are expected to have PbB concentrations exceeding 10 μg/dL, or an 

average risk for a child living in this neighborhood would be 58.1%/4=14.5%. The risk at two of 

the residences (houses 3 and 4) in the neighborhood is above the OSWER specified level of 

protectiveness which aims to limit exposure to PbS levels such that a typical child or a group of 

similarly exposed children would have an estimated risk of no more than 5 percent exceeding the 

PbB level of concern (typically 10 μg/dL). 

The use of aggregate neighborhood input data requires that the user compare the probability 

density function (PDF) and elevated PbB risk calculated from aggregate parameters with the 

correct PDF and elevated PbB risk functions, which are the mathematical composites of the 

individual PDF and risk functions. Expressed mathematically: 

true neighborhood PDF = (PDF(site 1) + PDF(site 2) +...)/N (Equation 6-1) 

true neighborhood risk = (risk(site 1) + risk(site 2) +...)/N (Equation 6-2) 

The approach outlined here does not require any mathematical assumptions about the distribution 

of soil and dust Pb concentrations, nor of any other parameters or variables except for PbB. The 

conditional distribution of individual PbB is assumed to be log-normal with a constant GSD 

(given specified values of Pb exposure variables that determine the geometric mean PbB for 

individuals in that exact environment). The method suggested is the most convenient and 

flexible framework determined for neighborhood assessment concerning the effect of PbS 

abatement. 

6.3 RISK ASSESSMENT USING GROUPED DATA FOR A NEIGHBORHOOD 

The example in the preceding section had a “neighborhood” with only four houses, so that the 

amount of work required was not very burdensome. In the real world, the site manager or risk 

assessor may be dealing with relatively homogeneous neighborhoods or small communities with 

several hundred households. These calculations can be simplified by grouping soil and dust lead 

levels into small cells with fixed ranges of values. The grouped data within each cell are all 

assigned the same value, such as the midpoint of the interval. 
34 

USER'S GUIDE FOR IEUBKWIN 

Each cell is then assigned a statistical weight. The statistical weights could be one or more of the 

following: 

1. The number of housing units with soil and dust lead concentrations in the interval. 

2. The number of children observed or expected to live in housing units with soil and 

dust lead concentrations in the interval. 

3. The fraction of housing in a neighborhood that is expected to have soil and dust lead 

concentrations in the interval. 

4. The fraction of area in as yet undeveloped neighborhoods with soil and dust lead 

concentrations in the interval. 

The PDF and risk of elevated PbB in children reflects the weighted sum of the cell PDF or cell 

risks. If the respective weights are denoted weight (cell 1), weight (cell 2), etc., and the PDFs 

are denoted PDF (cell 1), PDF (cell 2), etc., and the risks are denoted risk (cell 1), risk (cell 2), 

etc., then: 

neighborhood PDF = [weight (cell 1) * PDF (cell 1) + weight (cell 2) * 

PDF (cell 2) + etc.] / [weight (cell 1) + weight (cell 2) + etc.] (Equation 6-3) 

neighborhood risk = [weight (cell 1) * risk (cell 1) + weight call (cell 2) * 

risk (cell 2) + etc.] / [weight (cell 1) + weight (cell 2) + etc.] (Equation 6-4) 

The following hypothetical example may illustrate these points. Suppose that a random sample 

of 250 houses and apartments has been obtained in a neighborhood. The number of houses in 

each interval of 250 μg/g soil and 250 μg/g dust lead is shown in Table 6-3. This same example 

is shown in Table 6-4 in intervals of 500 μg/g in soil and 500 μg/g in dust. There is no 

requirement that there be equal interval lengths in either soil or dust. 

The user may then calculate neighborhood risk in any one of three ways: 

• Sum of risks for 250 housing units 

• Sum of risks for 14 cells or groups of width 250 μg/g soil and dust 

• Sum of risks for seven cells or groups of width 500 μg/g in soil and dust 

The results of calculations are shown in Tables 6-3 and 6-4. The total risk for the data shown in 

Table 6-3 is calculated as follows: 

(30 * 0.0.065% + 50 * 1.680% + 20 * 7.360% + 10 * 1.127% + 40 * 6.005% + 30 * 

14.814% + 20 * 25.597% + 10 * 13.001% + 20 * 23.582% + 10 * 34.585% + 3 * 

44.829% + 4 * 52.278% + 1 * 72.123% + 2 * 65.597%)/250 = 11.74% (Equation 6-5) 

The risk calculation for the data in Table 6-4 is similar. 

The total risk in Table 6-4 is calculated as follows: 

(130 * 1.386% + 70 * 15.745% + 10 * 12.123% + 30 * 33.604% + 7 * 53.049% + 1 * 

67.238% + 2 * 65.031%)/250 = 11.92% (Equation 6-6) 

If there are not too many cells, the amount of calculation can be noticeably reduced. However, 

as the intervals are made wider, there is a corresponding loss of accuracy in the neighborhood 
35 

USER'S GUIDE FOR IEUBKWIN 

risk estimate. The extra effort in calculating risks with 250 μg/g intervals (14 cells) is probably 

compensated by the increased precision, with an estimate of 11.74% instead of 11.92%. The 

individual risk, as shown by the calculated risk for the residences with higher soil and dust 

concentrations, for many residences in the neighborhood is above the OSWER specified level of 

protectiveness (no more than 5 percent exceeding typically 10 μg/dL). This illustrates the 

importance of calculating individual risk, rather than community risk, to achieve EPA's public 

health goal. 

6.4 RISK ASSESSMENT USING NEIGHBORHOOD OR NEIGHBORHOOD-SCALE INPUT 

There are situations in which it is either inconvenient or impossible to apply the IEUBK model at 

the intended household residence scale. For example, if only neighborhood mean values or 

geometric mean values of input parameters such as soil and dust lead are available, the model 

estimate may be far less reliable than if individual residential measurements were made. 

Another possibility is that there are a substantial number of soil and dust lead measurements at a 

site, but not at houses or locations within the site where blood lead and EBL risk estimates are 

needed, for example, to compare with blood leads observed at residences where there are no 

environmental data. There are some circumstances in which this is clearly not a valid application 

of the model. As we do not clearly understand the range of conditions under which the IEUBK 

model may be used with large-scale input data at this time, we must discourage use of the 

IEUBK model except with single-residence or residential lot-sized input data, or with data 

grouped into cells as in Section 6.3. 
36 

USER'S GUIDE FOR IEUBKWIN 

Table 6–3. Neighborhood Risk Estimation with Grouped Data 

Hypothetical example of grouped data for a neighborhood with dust and soil samples 

of 250 sites of house yards. Intervals are 250 μg/g in PbS and PbD. 

Risk2 

Soil 

interval 

Soil 

midpoint 

Dust 

interval 

Dust 

midpoint 

Statistical 

weight 

Geometric 

mean 

(μg/dL)1 

Probability 

of exceeding 

10 μg/dL 

0-249 125 0-249 125 30 2.2 0.065 

0-249 125 250-499 375 50 3.7 1.680 

0-249 125 500-749 625 20 5.1 7.360 

250-499 375 0-249 125 10 3.4 1.127 

250-499 375 250-499 375 40 4.8 6.005 

250-499 375 500-749 625 30 6.1 14.814 

250-499 375 750-999 875 20 7.3 25.579 

500-749 625 250-499 375 10 5.9 13.001 

500-749 625 500-749 625 20 7.1 23.582 

500-749 625 750-999 875 10 8.3 34.585 

500-749 625 1,000-1,249 1,125 3 9.4 44.829 

750-999 

750-999 

875 

875 

1,000-1,249 

1,750-1,999 

1,125 

1,875 

4 

1 

10.3 

13.2 

52.278 

72.123 

1,000-1,249 1, 125 1,250-1,499 1,375 2 12.1 65.597 

TOTAL 250 11.74 

1

 Calculated from IEUBK model with default parameters 2

 Assuming GSD=1.6 
37 

USER'S GUIDE FOR IEUBKWIN 

Table 6–4. Neighborhood Risk Estimation with Coarsely Grouped Data 

Hypothetical example of grouped data for a neighborhood 

with intervals of 500 μg/g in soil Pb and dust Pb. 

Risk2 

Geometric Probability 

Soil 

interval 

Soil 

midpoint 

Dust 

interval 

Dust 

midpoint 

Statistical 

weight 

mean 

(μg/dL)1 

of exceeding 

10 μg/dL 

0-499 

0-499 

250 

250 

0-499 

500-999 

250 

750 

130 

70 

3.6 

6.2 

1.386 

15.745 

500-999 750 0-499 250 10 5.8 12.123 

500-999 750 500-999 750 30 8.2 33.604 

500-999 750 1,000-1,499 1,250 7 10.4 53.049 

500-999 750 1,500-1,999 1,750 1 12.3 67.238 

1,000-1,499 1, 250 1,000-1,499 1,250 2 12.0 65.031 

TOTAL 250 11.92 

1

 Calculated from IEUBK model with default parameters, ages 0 to 84 months 2

 Assuming GSD=1.6 
38 

USER'S GUIDE FOR IEUBKWIN 

7.0 References 

Hastings, C. Approximations for Digital Computers. Princeton University Press. 1955. In: 

Handbook of Mathematical Functions with Formulas, Graphs and Mathematical Tables. M. 

Abramowitz, I.A. Stegun, Eds. National Bureau of Standards Applied Mathematics Series 55. 

Seventh Printing: 1968, p. 932. 

U.S. Environmental Protection Agency. Office of Solid Waste and Emergency Response. 

Clarification to the 1994 Revised Interim Soil Lead Guidance for CERCLA Sites and RCRA 

Corrective Action Facilities. OSWER Directive No. 9200.4-27P. Washington, DC: 1998. 

U.S. Environmental Protection Agency. Technical Review Workgroup for Lead. Integrated 

Exposure Uptake Biokinetic Model for Lead in Children (IEUBK). Version 0.99d. NTIS No. 

PB94-501517. Washington, DC: 1994. 

U.S. Environmental Protection Agency. Technical Review Workgroup for Lead. Guidance 

Manual for the Integrated Exposure Uptake Biokinetic Model for Lead in Children. OSWER 

Directive No. 9285.7-15-1, Document No. EPA/540/R-93/081. Washington, DC: 1994. 

U.S. Environmental Protection Agency. Office of Solid Waste and Emergency Response. 

Revised Interim Soil Lead Guidance for CERCLA Sites and RCRA Corrective Action Facilities. 

OSWER Directive No. 9355.4-12. Washington, DC: 1994. 

U.S. Environmental Protection Agency. Technical Review Workgroup for Lead. Technical 

Support Document: Parameters and Equations Used in the Integrated Exposure Uptake 

Biokinetic (IEUBK) Model for Lead in Children. Version 0.99d. OSWER Directive No. 9285.7-

22, NTIS No. PB 94-963505. Washington, DC: 1994. 

U.S. Environmental Protection Agency. Technical Review Workgroup for Lead. Reference 

Manual for the Integrated Exposure Uptake Biokinetic Model for Lead in Children, Windows 

Version. EPA/540/K-01/007. Washington, DC: 2001. 

U.S. Environmental Protection Agency. Technical Review Workgroup for Lead. System 

Requirements and Design for the Integrated Exposure Uptake Biokinetic Model for Lead in 

Children, Windows Version. EPA/540/K-01/006. Washington, DC: 2001. 

U.S. Food and Drug Administration. 2006. Total Diet Study. U. S. Food and Drug 

Administration Center for Food Safety and Applied Nutrition Office of Plant and Dairy Foods 

and Beverages (May 16, 2006). Available online at The U.S. Food and Drug Administration 

Center for Food Safety and Applied Nutrition Web site (http://www.cfsan.fda.gov/~comm/tdstoc.html). 

White, P., P. Van Leeuwen, B. Davis, M. Maddaloni, K. Hogan, A. Marcus, and R. Elias. 1998. 

U.S. Environmental Protection Agency. The Conceptual Structure of the Integrated Exposure 

Uptake Biokinetic Model for Lead in Children. Environmental Health Perspectives 106 

(Suppl. 6): 1513. 
39 

USER'S GUIDE FOR IEUBKWIN 

Zaragoza, L. and K. Hogan. 1998. U.S. Environmental Protection Agency. The Integrated 

Exposure Uptake Biokinetic Model for Lead in Children: Independent Validation and 

Verification. Environmental Health Perspectives 106 (Suppl. 6): 1555. 
40 

USER'S GUIDE FOR IEUBKWIN 

Appendix A: Using Spreadsheets with IEUBKwin 

A.1 IMPORTING IEUBKWIN DATA TO SPREADSHEET PACKAGES 

IEUBKwin data, including batch mode output can be readily exported to spreadsheets. The 

following information is provided to facilitate this process. 

The IEUBKwin output data (*.txt) for the risk assessment mode can be exported to a spreadsheet 

application (e.g., Excel or Lotus 1-2-3) for submission to EPA. The data is captured in a tabular 

format in IEUBKwin. To export output data to Excel, the user should employ the following 

procedure: 

1. Start Excel 

2. Click on File/Open and change Files of Type to All Files, locate your *.txt output file, 

and click Open. 

3. On the Text Import Wizard screen choose Delimited and click Next. Select Tab as the 

Delimiter and General as Column Data Format. Select Finish. 

4. Save the file in Excel format (*.xls). 

Figure A-1. Export IEUBKwin Data Output to Microsoft Excel. 
41 

USER'S GUIDE FOR IEUBKWIN 

To export output data to Lotus 1-2-3, the user should employ the following procedure: 

1. Start Lotus 1-2-3 

2. Click on File/Open and change Files of Type to All(*), locate your *.txt output file, 

and click Open. 

3. On the Text File Options screen choose Automatically Parse Based on File Layout. 

4. Save file in Lotus 1-2-3 format (*.123). 

To import data into Lotus 1-2-3, the user would employ the following procedure: 

1. Start Lotus 1-2-3. 

2. Click on File/Open and change Files of Type to All Files, locate your *.txt output file, 

and click Open. 

3. On the Text File Options screen choose Automatically Parse Based on File Layout. 

4. Save file in Lotus 1-2-3 format (*.123). 

Figure A-2. Export IEUBKwin Data Output to Lotus 1-2-3. 
42 

USER'S GUIDE FOR IEUBKWIN 

To import data to Microsoft Excel, the user would employ this procedure: 

1. Start Excel. 

2. Click on File/Open, change Files of Type to All (*), locate your *.txt output file, and 

click Open. 

3. On the Text Import Wizard screen choose Fixed Width and click Next. 

- Excel may have left out some column breaks or inserted extra column breaks. 

To insert additional column breaks, click at the desired position. To remove a 

column break, double-click it, click Next, select General Format, and click 

Finish. 

4. Save the file in Excel format (*.xls). 

Note that Excel will break the header text of the file into columns as well. Also, an IEUBKwin 

batch mode output file requires little to no editing before it is imported to other statistical 

programs. If the data file contains a null row, this may cause import problems with other 

spreadsheet packages. Once the results are loaded into a spreadsheet or statistical program, the 

user can apply a variety of graphical and statistical techniques in evaluating the output of 

IEUBKwin batch mode runs. Batch mode calculates the probability of exceedance as described 

in Appendix B. 

Figure A-3. Creating a Batch Data file with Microsoft Excel. 
43 

USER'S GUIDE FOR IEUBKWIN 

A.2 CREATING A BATCH MODE DATA INPUT FILE USING A SPREADSHEET 

As described in Chapter 3, batch mode input files require rigorous formatting. These files can be 

can be quickly and easily created by using spreadsheets. As an example, the following 

procedure describes creation of a batch mode data file in Microsoft Excel: 

1. Select the first 10 columns in your spreadsheet. 

2. Format the columns to have a width of 8.0. 

3. Right align all data (including the text descriptions at the top of the worksheet). 

4. Save the file with a Formatted text (space delimited) (*.prn) extension. The name you 

select should have no more than 8 characters or else the IEUBK model will truncate 

it. 

5. Manually change the file from *.prn to *.dat in your file directory. 

6. Run batch mode using the newly created file. 
44 

USER'S GUIDE FOR IEUBKWIN 

Appendix B: Probability Distribution Function 

The Z score is the distance between the PbB of 10 μg/dL and the geometric mean (GM) PbB, in 

standard normal units (Z score is also known as the standard normal deviate). Furthermore, the 

Z score is the inverse of the standard normal cumulative distribution function (i.e., normal 

distribution with mean of 0 and standard deviation of 1). The probability of a child’s blood lead 

level exceeding 10 μg/dL is calculated as 1– the area under the standard normal cumulative 

distribution function to the left of the Z score. For example: 

Given: 

GM PbB = 5 μg/dL (e.g., from IEUBKwin) 

GSD = 1.6 

Determine probability of exceedance: 

[ln ( ) − ln (5)]

ln ( ) = 1.48 10 Z = 16 .

Probability of child’s PbB exceeding 10 μg/dL (1-p) = 

1 −[Probability(Z <1.48))]= 0.93 = 0 .07 

After calculating the Z score, the IEUBKwin model simulates a standard normal distribution 

using the calculated GM and selected GSD. A difference approximation method is then used to 

calculate the probability of exceedance (1-p). This method has simplified the calculation from 

the IEUBK DOS version (IEUBK 0.99d). 

The z-score can also be used to estimate a percentile value for a lognormal distribution given a 

geometric mean and standard deviation: 

Z P X p = GM ⋅GSD

where, 

Xp = blood lead concentration at the pth percentile of the lognormal distribution 

GM = geometric mean of the distribution 

GSD = geometric standard deviation of the distribution 

Zp = z-score corresponding to the pth percentile of the standard normal cumulative distribution 

Note that taking the logarithm of both sides of the preceding equation and solving for Zp yields 

the equation for Z given above. The following is an example of using the preceding equation for 

calculating the blood lead concentration corresponding to a selected probability of exceedance 

(1-p): 

Calculate the 95th percentile blood lead concentration (Xp) 

Given: 

GM PbB = 5 μg/dL (e.g., from IEUBKwin) 

GSD = 1.6 

Zp = 1.645 (the 95th percentile Z score) . 5 1 6 )

1 645 Xp = ⋅( . . = 10 8 μg / dL 
45 

USER'S GUIDE FOR IEUBKWIN 

The results indicate there is a 5% probability of a child’s blood lead concentration exceeding 10.8 μg/dL, 

given a GM PbB concentration of 5 μg/dL and a GSD of 1.6. 
46 

USER'S GUIDE FOR IEUBKWIN 

Appendix C: Short Sheets Currently Available 

The TRW Lead Committee website has a complete listing of all Short Sheets that are related to lead risk 

assessments: http://www.epa.gov/superfund/lead/guidance.htm 

2000 Short Sheet: TRW Recommendations for Sampling and Analysis of Soil at Lead (Pb) Sites [EPA 

#540-F-00-010, OSWER #9285.7-38] (April 2000) to be consulted when using the IEUBK or the 

Adult Lead Methodology. 

Provides recommendations and protocols for the collection, preparation, and analysis of lead in soil 

and dust for use in lead modeling. 

1999 Short Sheet: IEUBK Model Soil/Dust Ingestion Rates [EPA #540-F-00-007, OSWER #9285.7-33] 

(December 1999) to be consulted when using the IEUBK model. 

Provides recommendations on the substitution of default soil/dust ingestion rates in the IEUBK 

model. 

1999 Short Sheet: IEUBK Model Bioavailability Variable [EPA #540-F-00-006, OSWER #9285.7-32] to 

be consulted when using the IEUBK or the Adult Lead Methodology. Discusses issues to consider 

and applicable methods for determining a site-specific bioavailability value for soil-borne lead. 

1998 Short Sheet: IEUBK Model Mass Fraction of Soil in Indoor Dust (MSD) Variable [EPA #540-F-00-

008, OSWER #9285.7-34] (June 1998) to be consulted when using the IEUBK model. 

Provides updated guidance on the Mass Fraction of Soil in Indoor Dust (MSD), the fraction of house 

dust that is derived from the outdoor soil. The MSD is a variable in the dust lead Multiple Source 

Analysis module of the IEUBK model. 

1997 Short Sheet: Overview of the IEUBK Model for Lead in Children [NTIS #PB99-9635-8, OSWER 

#9285.7-31] (August 1997) to be consulted when using the IEUBK model. 

Provides general information on the IEUBK model