APPENDIX B: SUMMARY OF REVISIONS TO

LEAD UPTAKE BIOKINETIC MODEL

SOFTWARE VERSIONS

B-1
TABLE B-1. SUMMARY OF REVISIONS TO LEAD UPTAKE/BIOKINETIC 

MODEL SOFTWARE FROM LEAD 0.2 TO LEAD 0.4 

Item Lead 0.2 (September, 1989) Lead 0.4 (September, 1990) GI-tract absorption model Default is linear "passive" model. Default is non-linear "active-passive" model Drinking water defaults Composite = 9 μg/L Composite = 4 μg/L 

First flush = 0 μg/L First flush = 4 μg/L Flushed = 9 μg/L Flushed = 1 μg/L Fountain = 0 μg/L Fountain = 10 μg/L % First flush = 0 % First flush = 50 % Flushed = 0 % Flushed = 35% % Fountain = 0 % Fountain = 15% 

(New defaults were provided EPA/ODW) 

Diet defaults Dietary lead intakes are based on FDA Dietary lead intakes are based on FDA surveys completed in 1988. Default values range from 

surveys completed in 1986. Default values 5.8-7.5 μg/day for ages 0-7. range from 22-34 μg/day for ages 0-7. 

Probability density function P(x) = (1/(2.51)(GSD))¡ P(x) = (1/(2.51)(x)(lnGSD))¡ exp((-1/2)((lnx-lnGM)/ lnGSD)2) 

exp((-1/2)((lnx-lnGM)/ lnGS D)2) 

Plot of probability density function Ordinate of "Bell-shaped plot" labelled Ordinate of "bell-shaped plot" labelled "probability density function f(blood lead)" numbers removed 

"probability". from ordinate. Probability is computed as the integral of this function over a specified ranged. This 

is graphically illustrated in the "S-shaped" probability percent plot. 

Calculation of blood lead in newborn Fixed at 6.4 μg/dL: User option: 1) As in Lead 0.2 and option to select maternal blood lead. 2) "Fetal" model, in (BPbn) BPbn=BPbm ¡ k, where which maternal blood lead is calculated based on user-defined exposure data and a maternal 

BPbm is the maternal blood biokinetic model, and newborn blood lead is calculated from biokinetic model. lead (7.5 μg/dL) and k is a constant (0.85). 

Soil/Dust primary data entry screen Menu includes "Change GI Absorption Menu revised to "Change GI Method/Bioavailability". If "yes" is selected, a window containing the 

Method" following message appears over the secondary data entry screen: "Bioavailability of soil lead may 

vary depending on the lead source. For example, lead from mine wastes may have a lower bioavailability than lead from smelters. Differences in bioavailability are thought to reflect differences in gastrointestinal absorption of specific lead species and particle sizes, which vary depending on the source. The following data entry screen allows the user to make adjustments in the gastrointestinal absorption coefficients to account for site-specific information on bioavailability. 

B-2
TABLE B-2. SUMMARY OF REVISIONS TO LEAD UPTAKE BIOKINETIC MODEL SOFTWARE 

FROM LEAD 0.4 TO LEAD 0.5 

Parameter or Feature Lead 0.4 (September, 1990) Lead 0.5 (December, 1990) (Non-linear GI Absorption Model Volume of GI-tract calculated, Volume of GI-tract calculated, VGI = (VGI)(GF). Default value for Km, 100 mg/L. 

VGI = (VGI)/(GF); where VGI is the adult GI-tract volume (liters) and GF is the age-dependent allometric scaling factor (GF < 1 for children). Default value for Km, 100 μg/L. 

Age Range Selection Menu specified selection. User designated option allows user to specify any designed age range from 1-7 years. Multiple Runs Multiple model runs are made manually; Allows user to input a range of lead values for one medium (air, diet, drinking water, dust or 

i.e., the user specifies input for each run, soil), and make a series of model runs in which lead levels in the specified medium are varied and saves output in Results Out file. over the specified range. 

X-axis Scaling Set by program. Allows user to set scaling of X-axis of probability density function and probability percent graphs 

manually. 

Overlay Graph Files Not available; graphs of individual model Allows user to save graph output (i.e., probability density function or probability percent graphs) 

runs can be displayed and/or printed. from multiple runs to an file and print output of multiple runs on a single graph. 

Text Files Data from individual model runs can be Allows user to save the data output of individual or multiple model runs, in user specified ASCI 

saved to a file. text files; these files can be reviewed and printed in Lead and/or imported into a word or 

processing program after exiting from Lead. 

Blood vs. Media Concentration: Model Not available. Allows user to input a range of lead values for one primary medium (air, diet, drinking water, Runs (Graph Output) dust or soil), and produce a series of model runs in which lead levels in the specified medium are 

varied over the specified range. The output of each run is captured in an X-Y plot of mean blood lead vs. medium lead. 

Blood vs. Media Concentration: Find Not available. Calculates a lead level in the user-specified medium that is associated with a specified mean blood 

lead. 

B-3
TABLE B-3. SUMMARY OF REVISIONS TO LEAD UPTAKE BIOKINETIC MODEL SOFTWARE 

FROM LEAD 0.5 TO LEAD 0.99d 

Parameter or Feature Lead 0.5 (December, 1990) Lead 0.99d (January, 1994) Batch Mode Model Runs Not available. Accepts a properly formatted ASCII text file (*.DAT) containing data on lead exposure and blood lead 

levels for a sample population, and calculates predicted blood lead levels for each individual. The output 

is saved as a *.TXT file that can be viewed within Lead or imported into a text editor (e.g., word processor), and as a *.ASC file that can be imported into PBSTAT for selected statistical analysis and graphic display. 

PBSTAT Not available. Accepts the output of batch mode operations (i.e., *.ASC files) and delivers statistical and graphic output 

selected by the user from a menu. PBSTAT can be accessed from the main menu of Lead, or externally with a DOS command (PBSTAT). The printer options in PBSTAT are the same as those in PBPLOT. 

PBPLOT Not available. Produces graph prints from Lead. It is accessed with a DOS command (PBPLOT). PBPLOT performs 

the same functions as "Graphics Selection Menu" in Lead, however, it produces graph prints at much higher resolutions (e.g. HP Plotter and PostScript printer graphs). PBPLOT accepts *.LAY and *.PBM 

files produced with Lead. 

Main Menu Restructured. Model Iteration Period One month with no user option. One day with user option. "Fetal" Model Maternal blood lead is calculated based Not available. 

on user-defined exposure data and a maternal biokinetic model, and newborn blood lead (BPbn) is calculated from a biokinetic model. 

Soil Intake Default value is 100 mg/day for all Default values are: 

ages. age soil intake 

(yr) (mg/day) 0-1 85 1-2 135 2-3 135 3-4 135 4-5 100 5-6 90 6-7 85 

View/Print Data File User must exit Lead and import *.TXT Allows the user to view and print *.TXT data files within Lead.

data files into a text editor (e.g., wordprocessor) to view or print data.

B-4
TABLE B-3 (cont'd). SUMMARY OF REVISIONS TO LEAD UPTAKE BIOKINETIC MODEL SOFTWARE 

FROM LEAD 0.5 TO LEAD 0.99d 

Parameter or Feature Lead 0.5 (December, 1990) Lead 0.99d (January, 1994) Contribution of soil lead to indoor dust lead Default value function is 0.28 μg Pb/g Default value function is 0.70 μg Pb/g dust per μg Pb/g of soil. 

dust per μg Pb/g of soil. 

Outdoor air lead concentration Default value is 0.2 μg/m3. Default value is 0.1 μg/m3. Dietary lead intake Default values were based on a Default values are based on a more detailed analysis of FDA 1988-90 data. 

preliminary analysis of 1988 FDA survey data. 

Editing of default biokinetic parameters Coding error resulted in changes to Coding error corrected. 

RECSUM time constants (e.g., TPLUR) not being accepted, as a result the UBM appeared to be insensitive to changes in TPLUR. 

Euler Algorithm Forward Euler algorithm calculates the Backward Euler algorithm calculates the increase compartmental lead mass over the iteration 

increase compartmental lead mass over interval as the total lead inflow to the compartment, minus the total lead outflow at the end of the the iteration interval as the total lead interval. inflow to the compartment, minus the total lead outflow at the beginning of the interval. 

Tissue Pb and Excretory Transfer Revised. Coefficients Non-linear GI Absorption Model "Non-integrated" approach: Saturable "Integrated" approach: Intakes from all media are considered in the calculation of the saturable 

absorption coefficients are calculated for absorption coefficients for each medium (via SATURATION(t). 

each medium (soil, diet, drinking water, etc.) based on intakes from each medium, and are used to calculate media-specific uptakes which are summed to yield total uptakes. 

B-5