Appendix A
A.1 Data Dictionary
A.2 Sensitivity Uncertainty
A.3 Model Considerations
A.4 Editors
A.5 Server Side
Appendix A
Attributes of the CCEF
To adequately assess the risks associated with chemicals released into the environment, researchers require tools for accurately estimating human exposure under a variety of exposure scenarios. Battelle will design a single overarching exposure modeling framework with the following features:
Comprehensive: applicable to exposure scenarios of interest to the chemical industry
Modular: consisting of modules (algorithms and databases), which can be easily updated and exchanged without affecting other parts of the framework
User-friendly: IBM or compatible personal computer application with a menu-driven interface
Multi-route: applicable to exposures via inhalation, oral, and dermal contact with consumer products
Multi-pathway: inhalation (air-to-lungs); dermal (liquid-to-skin, solid-to-skin, air-to-skin); oral (ingestion in food, hand-to-mouth, inhalation-to-ingestion, air-to-food-to-ingestion)
Multi-source: single or multiple compounds with the same target organ
Varying duration: applicable to acute, intermediate, and long-term exposures
Accurate: integrates state-of-the-art estimation methods and databases to estimate or reasonably overestimate the "ground-truth" of the actual exposure
Open code: accessible for inspection and review by users and stakeholders (no proprietary or "black box" code)
Probabilistic: provides realistic distribution of exposures within the exposed population based on probabilistic modeling of key exposure factors
Dose-response: converts exposure estimates to corresponding dose and risk values whenever appropriate
Mass-conservative: uses a mass balance approach whenever feasible to account for fate and transport of pollutant mass.
The design of the CCEF leverages the concepts associated with multiple existing framework system software and exposure modeling methods that are in the forefront of the scientific community, as well as new innovative concepts. The key to the CCEF will be its flexibility of use and ability to integrate and accommodate different exposure models (existing and future) required for the American Chemistry Council and industry needs.
The CCEF design links models and databases together so they can transparently communicate with each other. The CCEF is the overarching framework that houses the models and databases as "separate" objects and provides the data file protocols for communication between objects. A model is represented by a specific set of algorithms that perform a specific function (e.g., drinking water ingestion model). A module represents a general set of model types, defined by their "real world" functions, and includes the model, its user interface, and any pre- and post-processors that facilitate linkages and communication with/to other components (e.g., models and databases). This effort focuses on the design of an overarching framework and not on the models that are housed within the framework.
The name, Comprehensive Chemical Exposure Framework, evokes the nature of the software system, whose design is described herein.
Comprehensive refers to the ability to capture a wide scope of problems, issues, perspectives, and exposure scenarios of interest to the chemical industry.
Chemical refers most importantly to non-agricultural compounds, but when combined with Comprehensive, the design should allow for all types of chemicals (e.g., organic, inorganic, radioactive) to be addressed if a future requirement is needed. In other words, non-agricultural chemicals will be addressed, but the system should not necessarily be structured to exclude other chemicals.
Exposure refers to the manner in which people come in contact with chemicals, which could include exposure routes (e.g., inhalation, oral, and dermal contact) and exposure pathways [ingestion to food, hand-to-mouth, etc. (i.e., oral), liquid-/solid-/air-to-skin (i.e, dermal contact), and air-to-lungs (i.e., oral)].
Framework refers to the software structure of the CCEF, which allows for the incorporation and linkages of a confederation of models and databases. Note that the Framework houses models and databases, but the Framework itself does not represent a model in the system, although, technically speaking, it can and probably will be called a model. Within this document, the term model will refer to the software codes inside the Framework, and the Framework will represent the overall structure linking the models and databases to allow for a seamless transfer of data between components.
