Multi-criteria selection of human health scenarios due to private consumption

1. Purpose is to illustrate use of a system model approach for deriving at binary criteria approximations of sub-problems governing the two main problems at the most aggregated level, i.e. exposure and toxicity. Secondary to illustrate the use of these criteria as input parameters in the multi-criteria model developed by Peter Sorensen, its capacity for scenario descriptions and selection of high risk scenario exposure profiles related to defined risk problems. Purpose is to illustrate use of a system model approach for deriving at binary criteria approximations of sub-problems governing the two main problems at the most aggregated level, i.e. exposure and toxicity. Secondary to illustrate the use of these criteria as input parameters in the multi-criteria model developed by Peter Sorensen, its capacity for scenario descriptions and selection of high risk scenario exposure profiles related to defined risk problems.

2. Definition of the boundary conditions of a risk problem is essential due to the following reasons. Chemical exposures in terms of mixtures is a function of the present sources and emission in a given scenario, e.g. workplace exposure profiles within different industrial sectors vary and accordingly the potential / possibility of threatening health effects is given by the potential unwanted effects and critical exposure routes of the present chemicals. Definition of the boundary conditions of a risk problem is essential due to the following reasons. Chemical exposures in terms of mixtures is a function of the present sources and emission in a given scenario, e.g. workplace exposure profiles within different industrial sectors vary and accordingly the potential / possibility of threatening health effects is given by the potential unwanted effects and critical exposure routes of the present chemicals.

3. The Problem Specification Model includes all known sub-problems describing the two most aggregated sub-problems of the main problem, i.e. potential and realistic exposure and toxicity. For examples ….Sub-problems may reflect the fate patterns governing exposure or possible outcomes in terms of more general diseases specified at lower level, but higher specificity concerning the type of disease / health effect. The Scenario Composition Model includes the critical sub-problems governing the main problem. The Scenario Composition Model may be seen as the step or framing for design of hypothesis driven risk assessment activities in accordance to the defined Risk Problem Boundary. The Criteria Model is a model for assigning criteria to each sub-problem and constructing a criteria data management system for quantifying each sub-problem included in the Scenario Composition Model. The Scenario Selection Model is a multi-criteria methodology which are able to use all criteria values from the Critical Model as input variable in the analysis and selection of the highest risk exposure candidates / substances, e.g. regarding the specified health effects, for further risk assessment activities.The Problem Specification Model includes all known sub-problems describing the two most aggregated sub-problems of the main problem, i.e. potential and realistic exposure and toxicity. For examples ….Sub-problems may reflect the fate patterns governing exposure or possible outcomes in terms of more general diseases specified at lower level, but higher specificity concerning the type of disease / health effect. The Scenario Composition Model includes the critical sub-problems governing the main problem. The Scenario Composition Model may be seen as the step or framing for design of hypothesis driven risk assessment activities in accordance to the defined Risk Problem Boundary. The Criteria Model is a model for assigning criteria to each sub-problem and constructing a criteria data management system for quantifying each sub-problem included in the Scenario Composition Model. The Scenario Selection Model is a multi-criteria methodology which are able to use all criteria values from the Critical Model as input variable in the analysis and selection of the highest risk exposure candidates / substances, e.g. regarding the specified health effects, for further risk assessment activities.

4. Coloured sub-problems are excluded as sub-problems of minor importance regarding household exposure. Release, fate and toxicity are all selected as important. The toxicity can be claimed as most important due to a precaution approach where the hazard is highest for the most toxic substances. Industrial processing is selected to be the most important release as that is judged to be the release that is closest to the private consumer. Body entrance is selected as the most important fate factor as the link between release and exposure is close in case of private consumption, where the product typically is close to the human. Both acute and chronic toxicity is selected as important. However, the chronic effects can be claimed as more important than acute ones as the chronic effects represent a irreversible problem, where a chemical may show up to be harmful after a longer period of usage and thus to late to avoid serious problems. The release from consumer products is judged to be important for private consumption as this release is closest to the human body. Inhalation and ingestion is judged to be the most important way of body entrance. Neuro-developmental disorder, endocrine disruptor and genetic disorder are all considered as important sub-problems of chronic toxicity. However, carcinogenicity is selected to be the most important chronic effect due to the high mortality.Coloured sub-problems are excluded as sub-problems of minor importance regarding household exposure. Release, fate and toxicity are all selected as important. The toxicity can be claimed as most important due to a precaution approach where the hazard is highest for the most toxic substances. Industrial processing is selected to be the most important release as that is judged to be the release that is closest to the private consumer. Body entrance is selected as the most important fate factor as the link between release and exposure is close in case of private consumption, where the product typically is close to the human. Both acute and chronic toxicity is selected as important. However, the chronic effects can be claimed as more important than acute ones as the chronic effects represent a irreversible problem, where a chemical may show up to be harmful after a longer period of usage and thus to late to avoid serious problems. The release from consumer products is judged to be important for private consumption as this release is closest to the human body. Inhalation and ingestion is judged to be the most important way of body entrance. Neuro-developmental disorder, endocrine disruptor and genetic disorder are all considered as important sub-problems of chronic toxicity. However, carcinogenicity is selected to be the most important chronic effect due to the high mortality.

5. The following factors are selected from the problem tree: 1. Release from products is selected to be the most important release that is close to the private consumer. 2. The way of body entrance is selected as important as the link between release and exposure is close in case of private consumption, where the product typically is close to the human. Both inhalation and ingestion is judged to be the most important way of body entrance. 3. Both acute and chronic toxicity is selected as important. 4. Neuro-developmental disorder, Endocrine disruptor and genetic disorder are all considered as important factors for chronic toxicity. However, carcinogenic effect is further selected to be the most important chronic effect due to the high mortality. The following factors are selected from the problem tree: 1. Release from products is selected to be the most important release that is close to the private consumer. 2. The way of body entrance is selected as important as the link between release and exposure is close in case of private consumption, where the product typically is close to the human. Both inhalation and ingestion is judged to be the most important way of body entrance. 3. Both acute and chronic toxicity is selected as important. 4. Neuro-developmental disorder, Endocrine disruptor and genetic disorder are all considered as important factors for chronic toxicity. However, carcinogenic effect is further selected to be the most important chronic effect due to the high mortality.

8. Hasse Diagram including only realised positions in the Event Space, i.e. the 145 VOC and semi-VOC substances The Id 49 (sodium hydroxide) is negative for all the effect related descriptors and positive for all exposure descriptors, while Id 94 (benzene) is positive for all effect descriptors, but not for all exposure descriptors. The Id 94 has nine positive values, while the Id 49 only has six. This indicates a higher strength for Id 94 to rank upward compared to Id 49. Red circles indicate that more than one substance applies for the position by having the same descriptor values. In this way, Id 85 is included in Id 19. The Id 49 (sodium hydroxide) is negative for all the effect related descriptors and positive for all exposure descriptors, while Id 94 (benzene) is positive for all effect descriptors, but not for all exposure descriptors. The Id 94 has nine positive values, while the Id 49 only has six. This indicates a higher strength for Id 94 to rank upward compared to Id 49. Red circles indicate that more than one substance applies for the position by having the same descriptor values. In this way, Id 85 is included in Id 19.

9. Substances closest related to the top ranked substance (Id 94, benzene) represent the set of highest concern substances

10. The Event Space, as the word implies, includes all possible Events in terms of criteria value combinations based on the ten criteria. This means that there are 210 =1024 possible combinations of Criteria values and 1024 objects. Only 144 chemicals are included in this case study and therefore the Event Space includes 144 objects. However, a number of chemicals have the same criteria value combinations and therefore only 50 realised objects in terms of positions in the Event Space are present. As observed from the Hasse Diagram it includes eleven levels. The lowest level has only one possible Event or Criteria value combination, which is zero for all 10 criteria. The second lowest level has 10-1 zeros, the third lowest level include objects with 10-2, i.e. 8 zeros and two “1”….etc The top candidate of realised objects within the Event Space is benzene with ID 94, which has 10-9=1 zero and nine “1”. The fact that the Event Space includes less than 145 realised objects implies that several chemicals occupies the same position in the Event Space, and therefore have similar exposure and/or toxicity patterns. The higher level the higher risk of effects and exposureThe Event Space, as the word implies, includes all possible Events in terms of criteria value combinations based on the ten criteria. This means that there are 210 =1024 possible combinations of Criteria values and 1024 objects. Only 144 chemicals are included in this case study and therefore the Event Space includes 144 objects. However, a number of chemicals have the same criteria value combinations and therefore only 50 realised objects in terms of positions in the Event Space are present. As observed from the Hasse Diagram it includes eleven levels. The lowest level has only one possible Event or Criteria value combination, which is zero for all 10 criteria. The second lowest level has 10-1 zeros, the third lowest level include objects with 10-2, i.e. 8 zeros and two “1”….etc The top candidate of realised objects within the Event Space is benzene with ID 94, which has 10-9=1 zero and nine “1”. The fact that the Event Space includes less than 145 realised objects implies that several chemicals occupies the same position in the Event Space, and therefore have similar exposure and/or toxicity patterns. The higher level the higher risk of effects and exposure

11. Three cases form the input for the probability estimate: Case 1, where no a priori assumption is applied regarding the difference in criteria importance for the ranking. Case 2, where the criteria estimators of effect sub-problems (C1, C2, C3, C4) are assumed more important than the criteria estimators for exposure (C5, C6, C7, C8, C9, C10). Case 3, where the criteria estimators of chronic effects (C3, C4) are assumed more important than the acute effects (C1, C2) that again are assumed more important than a exposure criteria estimators (C5, C6, C7, C8, C9, C10). Three cases form the input for the probability estimate: Case 1, where no a priori assumption is applied regarding the difference in criteria importance for the ranking. Case 2, where the criteria estimators of effect sub-problems (C1, C2, C3, C4) are assumed more important than the criteria estimators for exposure (C5, C6, C7, C8, C9, C10). Case 3, where the criteria estimators of chronic effects (C3, C4) are assumed more important than the acute effects (C1, C2) that again are assumed more important than a exposure criteria estimators (C5, C6, C7, C8, C9, C10).

12. The horizontal spread in The horizontal spread in

13. Some simple observations concerning the test scenario

14. Additional facts! The absolute top candidate, i.e. highest risk chemical, is benzene Except for 2-butoxyethanol and ethylbenzene, all top candidates are have positive scores on the chronic toxicity criteria Two top candidates, i.e. solvent naphta and stoddard solvent, are not on the EU priority lists of chemicals. These are examples of top scores in the Danish emission inventory with an indicated high frequency of use in private household conditions having criteria values of 1 on all exposure estimator criteria except for Cr5, personal use. Both are acute toxic by inhalation, Cr1, and show potential for chronic and irreversible health effects, Cr3. Two top candidates, i.e. 2-butoxyethanol and ethylbenzene, have not been subjected to RA at EU level but are on the priority lists. These substances show no chronic toxicity related to Cr3 and Cr4. Both substances have a high frequency of use in terms of consumer product categories. 20% of nationwide exposure is contributed by various personal activities, such as driving and using attached garages. (Emissions from consumer products, building materials, paints, and adhesives may also be important, although data are largely lacking.) The traditional sources of atmospheric emissions (auto exhaust and industrial emissions) account for only about 20% of total exposure. Environmental tobacco smoke is an important source, accounting for about 5% of total nationwide exposure. A number of sources sometimes considered important, such as petroleum refining operations, petrochemical manufacturing, oil storage tanks, urban-industrial areas, service stations, certain foods, groundwater contamination, and underground gasoline leaks, appear to be unimportant on a nationwide basis.http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2477239&dopt=Citation 20% of nationwide exposure is contributed by various personal activities, such as driving and using attached garages. (Emissions from consumer products, building materials, paints, and adhesives may also be important, although data are largely lacking.) The traditional sources of atmospheric emissions (auto exhaust and industrial emissions) account for only about 20% of total exposure. Environmental tobacco smoke is an important source, accounting for about 5% of total nationwide exposure. A number of sources sometimes considered important, such as petroleum refining operations, petrochemical manufacturing, oil storage tanks, urban-industrial areas, service stations, certain foods, groundwater contamination, and underground gasoline leaks, appear to be unimportant on a nationwide basis.http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=2477239&dopt=Citation

15. The methodological Approach The System Model increases awareness of boundary conditions of the risk problems hypothesis driven approach Ignorance increases awareness uncertainty induced by delimitations of the problem three approximation of sub-problems by criteria increases awareness data availability and aggregation level of the scenario description The Multi Criteria Ranking model Input parameters / criteria values are binary thus only able to take one out of two possible values as “high” or “low” which makes it possible to define an Event Space that includes all possible criteria data values . which makes it possible to identify substances that have the same criteria data value combination the possibility of defining relative criteria importance prior to object ranking the ability of quantifying multi-attribute uncertainty

16. Thanks!