PNNL-SA-32283

Written by: Dennis Strenge

Prepared for the U.S. Department of Energy

Pacific Northwest National Laboratory
Operated by the U.S. Department of Energy
By Battelle




Requirements for the MEPAS Human Health Impact Module

1.0 Introduction

This document describes the requirements for the Multimedia Environmental Pollutant Assessment System (MEPAS) human health impact module. The module is specifically designed for inclusion in the Framework for Risk Analysis in Multimedia Environmental Systems (FRAMES), which is a platform that allows the linking of various multimedia modules into complete source/transport/exposure assessment systems (Whelan et al., 1997). These requirements can be used by software engineers and testers to ensure this module meets the needs of the clients and users.

2.0 Purpose of the MEPAS Human Health Impact Module

The MEPAS human health impact module calculates time-varying, contaminant (chemical and radionuclide) health impacts, as well as dose equivalence for radionuclides, as a function of exposure pathway and receptor. It uses the intake and dose equivalence results from an intake module to estimate health impacts for each exposure pathway. The health impacts for radionuclides are expressed as either the radiation dose equivalence and/or the risk of developing cancer, either as total incidence, fatal incidence, or incidence of severe genetic effects. Health impacts are expressed as the total incidence risk of developing cancer for carcinogenic chemicals, and adverse health effects are experienced as hazard index (HI) for non-carcinogenic chemicals. Table 1 shows the exposure pathways addressed by this module as a function of the transport media. The health impact module receives input data from intake modules, the chemical properties database, as well as data supplied by the user through a module user interface (MUI). The health impact results serve as the endpoint of a simulation.

3.0 Summary of Requirements for the MEPAS Human Health Impact Module

This section provides an overall summary of the requirements for the MEPAS human health impact module. Detailed input, output, and scientific requirements are described in Sections 4.0, 5.0, and 6.0 respectively.

The MEPAS human health impact module will

Table 1. MEPAS Human Health Impact Module Exposure Pathways for Each Transport Medium.

Exposure Pathway
Transport or Source Medium
 GroundWater   SurfaceWater   Atmosphere    Soil  
Ingestion of drinking water Yes Yes No No
Dermal contact with water while showering Yes Yes No No
Inadvertent ingestion of water while showering Yes Yes No No
Ingestion of leafy vegetables Yes Yes Yes Yes
Ingestion of other vegetables Yes Yes Yes Yes
Ingestion of meat Yes Yes Yes Yes
Ingestion of milk Yes Yes Yes Yes
Ingestion of finfish No Yes No No
Ingestion of shellfish No Yes No No
Inadvertent ingestion of water while swimming No Yes No No
Dermal contact with water while swimming No Yes No No
Dermal contact with sediment during shoreline use No Yes No No
Inadvertent ingestion of sediment during shoreline use No Yes No No
Inadvertent ingestion of soil No No Yes Yes
Dermal contact with soil No No Yes Yes
Indoor inhalation of volatile chemicals released from shower water Yes Yes No No
Indoor inhalation of volatile chemicals released from other domestic water uses Yes Yes No No
Inhalation of outdoor air from a passing plume No No Yes No
Inhalation of resuspended soil particles No No Yes Yes
External exposure to radionuclides while swimming No Yes No No
External exposure to radionuclides while boating No Yes No No
External exposure to radionuclides in sediment during shoreline use No Yes No No
External expousre to radionuclides in soil No No Yes Yes
External exposure to radionuclides in outdoor air from a passing plume No No Yes No
Measured concentrations in foods (special foods) n/a n/a n/a n/a

4.0 Input Requirements for the MEPAS Human Health Impact Module

Data needed to compute receptor health impacts are obtained from three sources.

The boundary conditions are communicated to the module through the Receptor Intake File (RIF). The input data supplied through the MUI is communicated to the model through the Global Input Data file (GID) and the model pre-processor. The GID file is also used to store the reference doses and conversion factors.

There are some general requirements associated with the MUI, which are

Specific input requirements for the MUI are as follows:

The data obtained from the RIF by the MEPAS human health impact module, and required for the module to perform its computations include average dose equivalence for the external radiation exposure to outdoor air pathway, average exposure medium concentrations for the other external radiation pathways, or average intake rates for the remaining pathways, for a specified time interval, contaminant (including progeny), and exposure location as contained in the RIF. Multiple exposure locations are allowed only for the atmospheric transport analysis.

As needed, the following data are obtained from the chemical properties database:

5.0 Output Requirements for the MEPAS Human Health Impact Module

The MEPAS human health impact module is required to produce a Health Impacts File (HIF) that contains time-varying, average contaminant risk or hazard index for each exposure pathway in accordance with the FRAMES data file specifications. The module also is required to produce a list file (*.HLS file) in ASCII format that documents the data actually read in by the model. The following data is output to the HIF:

6.0 Scientific Requirements for the MEPAS Human Health Impact Module

The scope of the human health impact analysis is determined by the modules that are connected to the exposure module (e.g. atmospheric transport and groundwater), and by the selections the user makes in the human health impact module MUI. The mathematical formulations for this module are provided in Strenge and Chamberlain (1995).

Scientific requirements for the impact module are as follows:

7.0 References

Strenge, D. L. and P. J. Chamberlain II. 1995. Multimedia Environmental Pollutant Assessment System (MEPAS): Exposure Pathway and Human Health Impact Assessment Models. PNL-10523. Pacific Northwest Laboratory, Richland, Washington.

Whelan G., K. J. Castleton, J. W. Buck, G. M. Gelston, B. L. Hoopes, M. A. Pelton, D. L. Strenge, and R. N Kickert. 1997. Concepts of a Framework for Risk Analysis in Multimedia Environmental Systems (FRAMES). PNNL-11748, Pacific Northwest National Laboratory, Richland, Washington.