6.0 Recommendations
6.1 Specific Research
6.2 Gap and Sensitivity
6.2.1 Summary of Recommendation for Gap and Sensitivity Analyses
This table summarizes the priority analysis for the four components of each scenario (Source, Transport, and Exposure & Impact). Select a hyper linked priority (high, medium, or low) for additional information based on each scenario. The reader can click on the different boxes of the table to see the details of the priority or scroll down and read the details manually in sections 6.2.2, 6.2.3, and 6.3.4.Table 6.2.1 Table of priority analysis conducted to produce a high, medium, and low scale for each model, database, and algorithm identified in the Gap and Sensitivity Analyses.
| Source | Transport | Exposure/Impact | |
|---|---|---|---|
| Scenario 1 | Low
(6.2.2.1) |
Medium
(6.2.3.1) |
High
(6.2.4.1) |
| Scenario 2 | Low
(6.2.2.2) |
Low
(6.2.3.2) |
High
(6.2.4.2) |
| Scenario 3 | High
(6.2.2.3) |
High
(6.2.3.3) |
Medium
(6.2.4.3) |
| Scenario 4 | High
(6.2.2.4) |
High
(6.2.3.4) |
Medium
(6.2.4.4) |
| High-missing data critical to model
Medium-could be missing data or poor algorithms Low-improve algorithms or data |
|||
6.2.2 Recommendations for Source Component
The research recommendations for the Source Component of the analysis will be defined by scenario because these components are very sensitive to the type of activities associated with each scenario. These recommendations for the Source Component are associated with the Gap and Sensitivity Analyses conducted in this study.Ranking of the models considered a number of factors, which are listed here roughly in decreasing level of importance: (1) whether the model evaluated is on the primary exposure pathway (e.g., inhalation, ingestion, dermal) for the scenario of interest, (2) whether the model recommended for a particular scenario needs to be developed or already exists, (3) the accuracy of the model, and (4) whether the model provides the output and time units needed for downstream components of the CCEF.
6.2.2.1 Recommendations for Source Component for Scenario 1
It is critical to have the important processes associated with the source of high volume chemicals to estimate the environmental concentration that may be available for exposure to humans of different sex and age. Fortunately, there are many models and algorithms that have been developed to support the micro-environmental modeling area. Based on Gap and Sensitivity Analyses, the following research recommendations are given a low priority for Source Components in Scenario 1:- There is a low priority to improve the algorithms associated with the source releases from painted walls. It was determined that the WPEM model did an adequate job of estimating the emissions of chemicals from painted walls. Thus, these research needs are low priority compared to the high priority research needs of the Exposure and Impacts Components for this scenario where models do not exist because of the lack of physiologic and chemical-specific data for the mother and fetus.
- There is a low priority to improve the algorithms associated with the source release from the stained wood ceilings. It was determined that the IAQX model did an adequate job of estimating the emissions of chemicals from wood stains. Thus, these research needs are low priority compared to the high priority research needs of the Exposure and Impacts Components for this scenario where models do not exist because of the lack of physiologic and chemical-specific data for the mother and fetus.
6.2.2.2 Recommendations for Source Component for Scenario 2
It is critical to have the important processes associated with the source of high volume chemicals to estimate the environmental concentration that may be available for exposure to humans of different sex and age. Fortunately, there are a several models and algorithms that have been developed to support the micro-environmental modeling area for Scenario 2. Based on Gap and Sensitivity Analyses, the following research recommendations are given a low priority for Source Component in Scenario 2:- There is a low priority to improve the algorithms associated with the source-term and transport modeling of the CONSEXPO model, which can be used to evaluate the primary exposure pathway for phthalate esters. It was determined that the CONSEXPO model did an adequate job of estimating indoor chemical concentrations of phthalate esters. Thus, these research needs are low priority compared to the high priority research needs of the Exposure and Impacts Components for this scenario where models do not exist because of the lack of physiologic and chemical-specific data for the mother, fetus, and pubescent offspring.
6.2.2.3 Recommendations for Source Component for Scenario 3
It is critical to have the important processes associated with the source of high volume chemicals to estimate the environmental concentration that may be available for exposure to adult male throughout his life. Fortunately, there are a good many models and algorithms that have been developed to support the micro-environmental modeling area. Based on Gap and Sensitivity Analyses, the following research recommendations are given a high priority for Source Component in Scenario 3:- There is a high priority for filling a research gap for a Fugitive Emissions source-term model. Currently, there are no readily available models to estimate this important process, and the lack of this information can potentially result in erroneous estimates of chemical concentrations resulting from fugitive emissions. Thus, these research needs are high priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
- There is a low priority for improvement of the PROMISE source-term model. It was determined that the PROMISE model did an adequate job of estimating the emissions of chemicals from spills. Thus, these research needs are low priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
- There is a low priority for improvement of a cigarette source-term model. Although a specific cigarette source term model was not identified, it was determined that cigarette models exist that can do an adequate job of estimating the emissions of chemicals from mainstream smoking. Thus, these research needs are low priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
6.2.2.4 Recommendations for Source Component for Scenario 4
It is critical to have the important processes associated with the source of high volume chemicals to estimate the environmental concentration that may be available for exposure to adult male throughout his life. Fortunately, there are a good many models and algorithms that have been developed to support the micro-environmental modeling area. Based on Gap and Sensitivity Analyses, the following research recommendations are given a high priority for Source Component in Scenario 4:- There is a high priority for filling a research gap for to model internal combustion engine source-term model. No widely published models were found to estimate this important process, and the lack of this information can potentially result in erroneous estimates of chemical concentrations in the breathing zone resulting from the combustion process. Thus, these research needs are high priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
- There is a high priority for filling a research gap for a Fueling source-term model. No widely published models were found to estimate this important process, and the lack of this information can potentially result in erroneous estimates of chemical concentrations resulting from the fueling process. Thus, these research needs are high priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
- There is a high priority for filling a research gap for Fueling Spills . No widely published frequency/volume data were found to estimate this important process, and the lack of this information can potentially result in erroneous estimates of chemical concentrations resulting from fueling spills. Thus, these research needs are high priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
- There is a medium priority for filling a research gap for Paint Spills. No widely published frequency/volume data were found to estimate this important process, and the lack of this information can potentially result in erroneous estimates of chemical concentrations resulting from fueling spills. Thus, these research needs are medium priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
- There is a low priority for improvement of the PROMISE, WPEM, IAQX, and Cigarette source-term model. It was determined that all these model did an adequate job of estimating the emissions of this scenario and chemicals. Thus, these research needs are low priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
6.2.3 Recommendations for Transport Component
The research recommendations for the Transport Component of the analysis will be defined by scenario because these components are very sensitive to the type of activities associated with each scenario. These recommendations for the Transport Component are associated with the Gap and Sensitivity Analyses conducted in this study.Ranking of the models considered a number of factors, which are listed here roughly in decreasing level of importance: (1) whether the model evaluated is on the primary exposure pathway (e.g., inhalation, ingestion, dermal) for the scenario of interest, (2) whether the model recommended for a particular scenario needs to be developed or already exists, (3) the accuracy of the model, and (4) whether the model provides the output and time units needed for downstream components of the CCEF.
6.2.3.1 Recommendations for Transport Component for Scenario 1
It is critical to have the important processes associated with transport of high volume chemicals to estimate the environmental concentration that may be available for exposure to humans of different sex and age. Fortunately, there are a good many models and algorithms that have been developed to support the micro-environmental modeling area. Based on Gap and Sensitivity Analyses, the following research recommendations are given a medium priority for Transport Component in Scenario 1:- There is a medium priority to fill a gap in the transport modeling of partitioning between vapor and particle phases. Currently, there are no models to estimate this important partitioning process and the lack of this information can potentially result in erroneous estimates of chemical concentrations in the vapor and particle phases. However, these research needs are medium priority compared to the high priority research needs of the Exposure and Impacts Components for this scenario where models do not exist because of the lack of physiologic and chemical-specific data for the mother and fetus.
- There is a medium priority to fill a gap in the transport modeling of dust particles via the resuspension process. Currently, there are no models to estimate this important process, and the lack of this information can potentially result in erroneous estimates of chemical concentrations resulting from the resuspension process. However, these research needs are medium priority compared to the high priority research needs of the Exposure and Impacts Components for this scenario where models do not exist because of the lack of physiologic and chemical-specific data for the mother and fetus.
- There is a low priority to improve the algorithms associated with the transport modeling of chemicals inside the room. It was determined that the CONTAMW model did an adequate job of estimating indoor chemical concentrations. Thus, these research needs are low priority compared to the high priority research needs of the Exposure and Impacts Components for this scenario where models do not exist because of lack of physiologic and chemical-specific data for the mother and fetus.
6.2.3.2 Recommendations for Transport Component for Scenario 2
It is critical to have the important processes associated with transport of high volume chemicals to estimate the environmental concentration that may be available for exposure to humans of different sex and age. Fortunately, there are a several models and algorithms that have been developed to support the micro-environmental modeling area for Scenario 2. Based on Gap and Sensitivity Analyses, the following research recommendations are given a low priority for the Transport Component in Scenario 2:- There is a low priority to improve the algorithms associated with the source-term and transport modeling of the CONSEXPO model, which can be used to evaluate the primary exposure pathway for phthalate esters. It was determined that the CONSEXPO model did an adequate job of estimating indoor chemical concentrations of phthalate esters. Thus, these research needs are low priority compared to the high priority research needs of the Exposure and Impacts Components for this scenario where models do not exist because of the lack of physiologic and chemical-specific data for the mother, fetus, and pubescent offspring.
- There is a low priority to fill a gap in the transport modeling of partitioning between vapor and particle phases. Currently, there are no models to estimate this important partitioning process and the lack of this information can potentially result in erroneous estimates of chemical concentrations in the vapor and particle phases. However, these research needs are low priority compared to the high priority research needs of the Exposure and Impacts Components for this scenario where models do not exist because of the lack of physiologic and chemical-specific data for the mother, fetus, and pubescent offspring, and because partitioning between vapor and particle phases is not part of the primary exposure pathway of phthalate esters.
- There is a low priority to improve the algorithms associated with the transport modeling of chemicals inside the room. It was determined that the CONTAMW model did an adequate job of estimating indoor chemical. Thus, these research needs are low priority compared to the high priority research needs of the Exposure and Impacts Components for this scenario where models do not exist because of the lack of physiologic and chemical-specific data for the mother, fetus, and pubescent offspring.
6.2.3.3 Recommendations for Transport Component for Scenario 3
It is critical to have the important processes associated with transport of high volume chemicals to estimate the environmental concentration that may be available for exposure to adult male throughout his life. Fortunately, there are a good many models and algorithms that have been developed to support the micro-environmental modeling area. Based on Gap and Sensitivity Analyses, the following research recommendations are given a high priority for Transport Component in Scenario 3:- There is a high priority to fill a gap in the transport modeling of partitioning between vapor and particle phases. Currently, there are no models to estimate this important partitioning process and the lack of this information can potentially result in erroneous estimates of chemical concentrations in the vapor and particle phases. Thus, these research needs are high priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
- There is a high priority to fill a gap in the transport modeling of dust particles via the resuspension process. Currently, there are no models to estimate this important process, and the lack of this information can potentially result in erroneous estimates of chemical concentrations resulting from the resuspension process. Thus, these research needs are high priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
- There is a low priority to improve the algorithms associated with the transport modeling of chemicals inside the room. It was determined that the CONTAMW model did an adequate job of estimating indoor chemical concentrations. Thus, these research needs are low priority compared to the research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
6.2.3.4 Recommendations for Transport Component for Scenario 4
It is critical to have the important processes associated with transport of high volume chemicals to estimate the environmental concentration that may be available for exposure to adult male throughout his life. Fortunately, there are a good many models and algorithms that have been developed to support the micro-environmental modeling area. Based on Gap and Sensitivity Analyses, the following research recommendations are given a high priority for Transport Component in Scenario 4:- There is a high priority to fill a gap in the transport modeling of partitioning between vapor and particle phases. Currently, there are no models to estimate this important partitioning process and the lack of this information can potentially result in erroneous estimates of chemical concentrations in the vapor and particle phases. Thus, these research needs are high priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
- There is a high priority to fill a gap in the transport modeling of dust particles via the resuspension process. Currently, there are no models to estimate this important process, and the lack of this information can potentially result in erroneous estimates of chemical concentrations resulting from the resuspension Process. Thus, these research needs are high priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
- There is a low priority to improve the algorithms associated with the transport modeling of chemicals inside the room. It was determined that the CONTAMW model did an adequate job of estimating indoor chemical concentrations. Thus, these research needs are low priority compared to the medium priority research needs of the Exposure and Impacts Components for this scenario where adult male PBPK and PBPD models exist and have adequate physiologic and chemical-specific data.
6.2.4 Recommendations for Exposure and Impact Components
The research recommendations for the Exposure and Impact Components of the analysis will be defined by scenario because these components are very sensitive to the type and age of the human involved. All of the recommendations for the Exposure and Impact Components are associated with the Gap Analysis because there were so little data to conduct a qualitative sensitivity analysis on these components.6.2.4.1 Recommendations for Exposure and Impact Components for Scenario 1
Physiologic and chemical-specific data are needed for both humans and appropriate laboratory animal species in order to construct useful PBPK and PBPD models. Based on Gap Analysis and the inadequate data for the models associated with pregnant mother and fetuses compared to the Source and Transport Components, the following research recommendations are given a high priority for Scenario 1:- Obtain key physiological data for pregnant female and the fetus (including maternal fetal transfer).
- Obtain key physiological data for lactating female and nursing and non-nursing offspring.
- Identify target tissues and the specific nature of the interactions of parent compound and/or metabolites with those tissues that result in toxicity to the organism.
- Correlate alterations in physiologic status (i.e. due to pregnancy, parturition, lactation, etc) with changes in interactions with target tissues.
6.2.4.2 Recommendations for Exposure and Impact Components for Scenario 2
Physiologic and chemical-specific data are needed for both humans and appropriate laboratory animal species in order to construct useful PBPK and PBPD models. Based on Gap Analysis and the inadequate data for the models associated with pregnant mother and fetuses compared to the Source and Transport Components, the following research recommendations are given a high priority for Scenario 2:- Obtain key physiological data for pregnant female and the fetus (including maternal fetal transfer).
- Obtain key physiological data for lactating female and nursing and non-nursing offspring.
- Obtain key physiological data for developing and pubescent offspring. Knowledge of key hormonal changes and status during development and puberty are especially important when modeling the effects of exposure to phthalates as they are known or suspected to cause endocrine disruption.
- Identify target tissues and the specific nature of the interactions of parent compound and/or metabolites with those tissues that result in toxicity to the organism.
- Correlate alterations in physiologic status (i.e. due to pregnancy, parturition, lactation, puberty, etc) with changes in interactions with target tissues.
6.2.4.3 Recommendations for Exposure and Impact Components for Scenario 3
Based on Gap Analysis and the adequate data for the models associated with adult males compared to the Source and Transport Components, the following research recommendations are given a medium priority for Scenario 3:- Available physiological data for the adult male, both human and rat, are more detailed than for pregnant females, fetuses, and offspring although more accurate values would increase the usefulness of the models.
- Research into the nature of the interactions between cigarette smoke and the Compounds in Group D would help in formulating appropriate models for this scenario.
6.2.4.4 Recommendations for Exposure and Impact Components for Scenario 4
Based on Gap Analysis and the adequate data for the models associated with adult males compared to the Source and Transport Components, the following research recommendations are given a medium priority for Scenario 4:- Obtain key physiological data pertinent to senescent males (>65 year for the human), human and rat, to allow formulation of models that are capable of accounting for age-related changes in physiological parameters.
- As identified in Scenario 1, in order to accurately model toxicant and/or metabolite interactions with target tissues the specific nature of the interactions needs to be more specifically identified for Compounds A and B and E, 2-butoxyethanol, ethylene glycol and methyl t-butyl ether, respectively. Further, these interactions need to be correlated with age-related changes in physiologic status.
