Asbestiform Fibers Nonoccupational Health Risks (1984) / Chapter Skim
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Appendix H: Comparative Risk Assessment Score Sheets
Appendix H: Comparative Risk Assessment Score Sheets
Pages 314-331
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From page 314... ...
Thus, the quantitative risk assessment suggested that for lifetime exposures to asbestos in ambient air, mesothelioma risks could easily exceed lung cancer risks by more than a factor of 10, which would result in a comparative risk score for mesothelioma of ++. With respect to the prime cell, all comparative risks have been judged to be either - or -- , meaning that they are less or much less important than for the prime cell, even though some of the indicators of risk are positive or more strongly negative.
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From page 315... ...
The committee' ~ evaluations were based on the following scoring convent ions: 0: Within a factor of about 2 of the corresponding values for the prime cell (in the sense of its effect on the total number and severity of effects) ; for example , if production were between 0.5 and 2.0 times that of chrysotile, the score would be 0.
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From page 316... ...
The following code was used for this purpose: a: reasonable assurance that comparative risk is in the direction indicated and approximately of the correct magnitude (e.g., if the risk compared with the prime cell was shown as " -- ", then it is probable , although not assured, that the effects are less than 0.1 times the effec t s for the prime cell) b: comparative risk is probably in the direction indicated, but the level is in great doubt c: comparative risk is highly uncertain due to paucity of information; this does not mean that the committee believes that the cell is very likely to provide as much risk as the prime cell, only that there is little information assuring a lower risk
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From page 317... ...
Most is probably excreted rapidly, but the amount that moves into the body is not known. Both epidemiological and animal studies have generally yielded "negative" results, but the epidemiological studies have been too insensitive to detect relatively small effects.
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From page 318... ...
Ingested asbestos is more likely to be excreted rapidly than is inhaled asbestos.
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From page 319... ...
On the other hand, many investigators believe that equal exposures to crocidolite and chrysotile will result in more cancer from the former, possibly from crocidolite' ~ greater ability to penetrate to the lung and its greater stability once there, rather than from a fundamental difference in potency at the since. Anus, the lower risk assessment is due almost entirely to much lower likelihood of significant nonoccupational exposures .
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From page 320... ...
320 COMPARATIVE RISK ASSESSMENT SCORE SHEET Cell Scored ~ Fiber Effect Route Scores Compared Chrysotile / Mesothelioma / Inhalation with Cell Fiber Effect Route Exposure Score Biodisposition Score Effects Score Production Use Pattern Geography Population 0 Morphology Chemistry Penetration Trends - Stability Overall risk compared with cell above Overall rick compared with prime cell Quality of comparative risk assessment Remarks: Fiber Size 0 Human Studies + o a Animal Studies 0 In-Vitro Studies O Synergism Other o As with lung cancer, crocidolite appears to be more effective for the same exposures, but current lower exposures and decreasing trends significantly reduce the risk for croc idolite.
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From page 321... ...
None of the other asbestos fibers are used to a great extent in conduce, so their exposure potential is associated with their natural occurrence or contamination of other produc t ~ such as talc .
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From page 322... ...
Most of the indicators for biological activity point toward lower risk. Evidence from human studies suggests lower, although not necessarily zero, risk of lung cancer.
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From page 323... ...
323 COMPARATIVE RISK ASSESSMENT SCORE SHEET Cell Scored Fibrous Glass / Mesothelioma / Inhalation Fiber Effect Route Scores Compared Chrysotile / Mesothelioma / Inhalation with Cell Fiber Effect Route 1' Exposure Score Biodisposition Score Effects Score Production Use Pattern Geography Fiber S ize Morphology Chemistry o In-Vitro Studies _ . ~ Population ~ Penetration -- Synergism Trends + Stability - Other Overall risk compared with cell above Overall risk compared with prime cell Quality of comparative risk assessment b Remarks: Human Studies Animal Studies O Epidemiological studies suggest that the association of a mesothelioma with fibrous glass is weaker than it is for lung cancer, but animal experiments have demonstrated the induction of mesothelioma with implanted material.
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From page 324... ...
Evidence is being collected on attapulgite miners, but no positive results have been obtained to date. Positive animal evidence suggesting biological activity is sparse.
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From page 325... ...
Average f iber size is somewhat thicker. Scanty results from studies in occupational cohorts and animals suggest that mineral wool is no more potent than asbestos ~ and probably less ~
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From page 326... ...
326 COMPARATIVE RISK ASSESSMENT SCORE SHEET Cell Scored Chrysotile Scores Compared with Cell Fiber Minera ect Route Mesothelioma / Inhalation Effect Route Exposure Score Biodisposition Score Effects Score Production - Fiber Size - Human Studies O Use Pattern - Morphology O Animal Studies O Geography O Chemistry In-Vitro Studies _ Population O Penetration - Synergism Trends + Stability Other Overall risk compared with cell above Overall risk compared with prime eel 1 Quality of comparative risk assessment Remarks: See remarks for lung cancer on previous page.
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From page 327... ...
In-Vitro Studies Synergism Other
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From page 328... ...
Little information is available on biological effects.
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From page 329... ...
329 COMPARATIVE RISK ASSESSMENT SCORE SHEET Cell Scored Ceramic Fiber / Mesothelioma / Inhalation Fiber Effect Route Scores Compared Chrysotile / Mesothelioma / Inhalation with Cell Fiber Effect Route Exposure Score Biodiaposition Score Effects Score Production Use Pattern Fiber Size O Human Studie __ Geography Population - Penetration O Synergism Trends ~ + Stability Other Morphology Chemistry Overall risk compared with cell above Overall risk compared with prime cell Quality of comparative risk assessment c Remarks: See remarks on previous page. SO Animal Studies O In-Vitro Studies .
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From page 330... ...
330 COMPARATIVE RISK ASSESSMENT SCORE SHEET Cell Scored Carbon Fiber / Lung Cancer / Inhalation - Fiber Effect Route Scores Compared Chrysotile / Lung Cancer / Inhalation with Cell Fiber Effect Route Exposure Score Biodisposition Score Effects Score Production Use Pattern Geography Population Fiber S ize O Human Stud ie s Morphology O Animal Studies Chemi s t ry In-Vi ~ ro Stud ie s Penetration O Synergism Trends +++ Stability _ Other Overall risk compared with cell above Overall risk compared with prime cell Quality of comparative risk assessment c Remarks: l Assessment is based almost entirely on consideration of the currently low exposure levels r
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From page 331... ...
331 COMPARATIVE RISK ASSESSMENT SCORE SHEET Ce 11 Scored Carbon Fib Fiber Effect Route Scores Compared ChrYsotile / Mesothelioma / Inhalation with Cell Fiber Effect Route Exposure Score Biodisposition Score Effects Score Produc t ion Use Pattern Fiber Size ~Human Studies ___ Geography Population - Penetration O Synergism Trends +++ Stability Other Morphology O Semis try Overall risk compared with cell above Overall risk compared with prime cell Quality of comparative risk assessment c Remarks: Animal Studies In-Vitro Studies See remarks for lung cancer on previous page.
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