Introduction: Low cumulative fiber exposure (CFE) is associated with health effects in a Libby vermiculite exposed cohort. This study refines the original 1980 exposure estimates and compares the CFE results.
Methods: CFE estimates were developed using three times more industrial hygiene measurements and long-term worker’s input. New adjustments included vermiculite ore source, seasonal overtime hours, time spent in various tasks and recollection of historical dustiness.
Results: The overall mean CFE and 95% confidence interval (n=513) in 1980 (0.80 [0.7,0.9]) fiber-yr/cc was statistically similar to the CFE results in 2010 (0.74 [0.6,0.9]). The mean CFE in the lowest exposure category (> 0 - 2 fiber-yr/cc) decreased from 0.36 in 1980 to 0.22 fiber-yr/cc in 2010 (p < 0.05). Revised CFEs extended the upper bound of the range of the 1980 estimate from 28.10 to 106.31 fiber-yr/cc.
Conclusions: The range of CFE values was expanded. These estimates may be useful in understanding health outcomes of workers and residents exposed to Libby vermiculite.
","abstract_html":"<p>Introduction: Low cumulative fiber exposure (CFE) is associated with health effects in a Libby vermiculite exposed cohort. This study refines the original 1980 exposure estimates and compares the CFE results. </p><p>Methods: CFE estimates were developed using three times more industrial hygiene measurements and long-term worker’s input. New adjustments included vermiculite ore source, seasonal overtime hours, time spent in various tasks and recollection of historical dustiness.</p><p>Results: The overall mean CFE and 95% confidence interval (n=513) in 1980 (0.80 [0.7,0.9]) fiber-yr/cc was statistically similar to the CFE results in 2010 (0.74 [0.6,0.9]). The mean CFE in the lowest exposure category (> 0 - 2 fiber-yr/cc) decreased from 0.36 in 1980 to 0.22 fiber-yr/cc in 2010 (p < 0.05). Revised CFEs extended the upper bound of the range of the 1980 estimate from 28.10 to 106.31 fiber-yr/cc.</p><p>Conclusions: The range of CFE values was expanded. These estimates may be useful in understanding health outcomes of workers and residents exposed to Libby vermiculite.</p>","abstract_has_math":false,"creators":["Borton, Eric K."],"institution":"University of Cincinnati","degree_name":"MS","degree_level":"masters","degree_discipline":"Medicine: Epidemiology (Environmental Health)","degree_department":null,"school":null,"contributors":["Lemasters, Grace"],"advisors":[],"committee_chairs":[],"committee_members":[],"year":2012,"date_issued":"2012","date_published":"2012","updated_at":"2026-07-24T03:36:23Z","subjects":["Epidemiology","Vermiculite","Asbestos","Mineral Fibers","Cumulative Fiber Exposure","Fiber Estimates","Libby"],"languages":["English"],"rights":["unrestricted","This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws."],"rights_urls":[],"identifier_entries":[]},"links":{"outbound_url":"http://rave.ohiolink.edu/etdc/view?acc_num=ucin1335461760","outbound_label":"Repository record","outbound_source":"dc:identifier"},"metadata_groups":[{"id":"people","label":"People","entries":[{"key":"dc:contributor","label":"Contributor","values":["Lemasters, Grace"]},{"key":"dc:creator","label":"Author","values":["Borton, Eric K."]}]},{"id":"academic_context","label":"Academic Context","entries":[{"key":"dc:date","label":"Dc Date","values":["2012"]},{"key":"dc:publisher","label":"Institution","values":["University of Cincinnati / OhioLINK"]},{"key":"dc:type","label":"Dc Type","values":["Electronic Thesis or Dissertation"]},{"key":"thesis:degree_discipline","label":"Discipline","values":["Medicine: Epidemiology (Environmental Health)"]},{"key":"thesis:degree_level","label":"Degree Level","values":["masters"]},{"key":"thesis:degree_name","label":"Degree Name","values":["MS"]},{"key":"thesis:institution_name","label":"Thesis Institution Name","values":["University of Cincinnati"]}]},{"id":"subjects_keywords","label":"Subjects and Keywords","entries":[{"key":"dc:subject","label":"Dc Subject","values":["Epidemiology","Vermiculite","Asbestos","Mineral Fibers","Cumulative Fiber Exposure","Fiber Estimates","Libby"]}]},{"id":"language_rights","label":"Language and Rights","entries":[{"key":"dc:language","label":"Dc Language","values":["English"]},{"key":"dc:rights","label":"Dc Rights","values":["unrestricted","This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws."]}]},{"id":"identifiers","label":"Identifiers","entries":[{"key":"dc:identifier","label":"Identifier","values":["http://rave.ohiolink.edu/etdc/view?acc_num=ucin1335461760"]}]},{"id":"additional","label":"Additional Metadata","entries":[{"key":"dc:description","label":"Description","values":["Introduction: Low cumulative fiber exposure (CFE) is associated with health effects in a Libby vermiculite exposed cohort. This study refines the original 1980 exposure estimates and compares the CFE results.
Methods: CFE estimates were developed using three times more industrial hygiene measurements and long-term worker’s input. New adjustments included vermiculite ore source, seasonal overtime hours, time spent in various tasks and recollection of historical dustiness.
Results: The overall mean CFE and 95% confidence interval (n=513) in 1980 (0.80 [0.7,0.9]) fiber-yr/cc was statistically similar to the CFE results in 2010 (0.74 [0.6,0.9]). The mean CFE in the lowest exposure category (> 0 - 2 fiber-yr/cc) decreased from 0.36 in 1980 to 0.22 fiber-yr/cc in 2010 (p < 0.05). Revised CFEs extended the upper bound of the range of the 1980 estimate from 28.10 to 106.31 fiber-yr/cc.
Conclusions: The range of CFE values was expanded. These estimates may be useful in understanding health outcomes of workers and residents exposed to Libby vermiculite.
"]},{"key":"dc:format","label":"Dc Format","values":["application/pdf","p.36","645.2 KB"]},{"key":"dc:title","label":"Title","values":["Update and comparison of cumulative fiber exposure estimates for workers in a facility expanding Libby vermiculite"]}]}],"canonical_facts":{"dc:contributor":["Lemasters, Grace"],"dc:creator":["Borton, Eric K."],"dc:date":["2012"],"dc:description":["Introduction: Low cumulative fiber exposure (CFE) is associated with health effects in a Libby vermiculite exposed cohort. This study refines the original 1980 exposure estimates and compares the CFE results.
Methods: CFE estimates were developed using three times more industrial hygiene measurements and long-term worker’s input. New adjustments included vermiculite ore source, seasonal overtime hours, time spent in various tasks and recollection of historical dustiness.
Results: The overall mean CFE and 95% confidence interval (n=513) in 1980 (0.80 [0.7,0.9]) fiber-yr/cc was statistically similar to the CFE results in 2010 (0.74 [0.6,0.9]). The mean CFE in the lowest exposure category (> 0 - 2 fiber-yr/cc) decreased from 0.36 in 1980 to 0.22 fiber-yr/cc in 2010 (p < 0.05). Revised CFEs extended the upper bound of the range of the 1980 estimate from 28.10 to 106.31 fiber-yr/cc.
Conclusions: The range of CFE values was expanded. These estimates may be useful in understanding health outcomes of workers and residents exposed to Libby vermiculite.
"],"dc:format":["application/pdf","p.36","645.2 KB"],"dc:identifier":["http://rave.ohiolink.edu/etdc/view?acc_num=ucin1335461760"],"dc:language":["English"],"dc:publisher":["University of Cincinnati / OhioLINK"],"dc:rights":["unrestricted","This thesis or dissertation is protected by copyright: all rights reserved. It may not be copied or redistributed beyond the terms of applicable copyright laws."],"dc:subject":["Epidemiology","Vermiculite","Asbestos","Mineral Fibers","Cumulative Fiber Exposure","Fiber Estimates","Libby"],"dc:title":["Update and comparison of cumulative fiber exposure estimates for workers in a facility expanding Libby vermiculite"],"dc:type":["Electronic Thesis or Dissertation"],"thesis:degree_discipline":["Medicine: Epidemiology (Environmental Health)"],"thesis:degree_level":["masters"],"thesis:degree_name":["MS"],"thesis:institution_name":["University of Cincinnati"]},"updated_at":"2026-07-24T03:36:23Z"}