title: Modeling community asbestos exposure near a vermiculite processing facility: Impact of human activities on cumulative exposure.
abstract: Contaminated vermiculite ore from Libby, Montana was processed in northeast Minneapolis from 1936 to 1989 in a densely populated urban residential neighborhood, resulting in non-occupational exposure scenarios from plant stack and fugitive emissions as well as from activity-based scenarios associated with use of the waste rock in the surrounding community. The objective of this analysis was to estimate potential cumulative asbestos exposure for all non-occupationally exposed members of this community. Questionnaire data from a neighborhood-exposure assessment ascertained frequency of potential contact with vermiculite processing waste. Monte Carlo simulation was used to develop exposure estimates based on activity-based concentration estimates and contact durations for four scenarios: S1, moved asbestos-contaminated waste; S2, used waste at home, on lawn or garden; S3, installed/removed vermiculite insulation; S4, played in or around waste piles at the plant. The simulation outputs were combined with air-dispersion model results to provide total cumulative asbestos exposure estimates for the cohort. Fiber emissions from the plant were the largest source of exposure for the majority of the cohort, with geometric mean cumulative exposures of 0.02 fibers/cc × month. The addition of S1, S2 and S3 did not significantly increase total cumulative exposure above background exposure estimates obtained from dispersion modeling. Activity-based exposures were a substantial contributor to the upper end of the exposure distribution: 90th percentile S4 exposure estimates are ∼10 times higher than exposures from plant emissions. Pile playing is the strongest source of asbestos exposure in this cohort, with other activity scenarios contributing less than from plant emissions.
authors.affiliation: University of Minnesota School of Public Health, Division of Environmental Health Sciences, Mayo Mail Code 807, 420 Delaware St. SE, Minneapolis, Minnesota 55455, USA. john.adgate@ucdenver.edu
authors.forename: John L
authors.initials: JL
authors.lastname: Adgate
authors.forename: Sook Ja
authors.initials: SJ
authors.lastname: Cho
authors.forename: Bruce H
authors.initials: BH
authors.lastname: Alexander
authors.forename: Gurmurthy
authors.initials: G
authors.lastname: Ramachandran
authors.forename: Katherine K
authors.initials: KK
authors.lastname: Raleigh
authors.forename: Jean
authors.initials: J
authors.lastname: Johnson
authors.forename: Rita B
authors.initials: RB
authors.lastname: Messing
authors.forename: A L
authors.initials: AL
authors.lastname: Williams
authors.forename: James
authors.initials: J
authors.lastname: Kelly
authors.forename: Gregory C
authors.initials: GC
authors.lastname: Pratt
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000538:Aluminum Silicates; D001194:Asbestos / Q000032:analysis* / Q000633:toxicity; D015331:Cohort Studies; D003198:Computer Simulation; D004781:Environmental Exposure / Q000032:analysis*; D005260:Female; D006801:Humans; D007221:Industry; D008297:Male; D008875:Middle Aged; D008954:Models, Biological; D009010:Monte Carlo Method; D016273:Occupational Exposure / Q000032:analysis; D012111:Residence Characteristics; D018570:Risk Assessment / Q000379:methods; D013997:Time Factors; D055815:Young Adult
chemical_list: D000538:Aluminum Silicates; C003760:vermiculite; D001194:Asbestos