title: A biopersistence study following exposure to chrysotile asbestos alone or in combination with fine particles.
abstract: In designing a study to evaluate the inhalation biopersistence of a chrysotile asbestos that was used as a component of a joint-compound, a feasibility study was initiated to evaluate the short-term biopersistence of the chrysotile alone and of the chrysotile in combination with the sanded reformulated joint-compound. Two groups of Wistar rats were exposed to either 7RF3 chrysotile (Group 2) or to 7RF3 chrysotile combined with aerosolized sanded joint-compound (Group 3). In addition, a control group was exposed to filtered-air. The chrysotile used in the Ready Mix joint compound is rapidly removed from the lung. The chrysotile alone exposure group had a clearance half-time of fibers L > 20 microm of 2.2 days; in the chrysotile plus sanded exposure group the clearance half-time of fibers L > 20 microm was 2.8 days. However, across all size ranges there was approximately an order of magnitude decrease in the mean number of fibers remaining in the lungs of Group 3 as compared to Group 2 despite similiar aerosol exposures. Histopathological examination showed that the chrysotile exposed lungs had the same appearance as the filtered-air controls. This study uniquely illustrates that additional concurrent exposure to an aerosol of the sanded joint-compound, with large numbers of fine-particles depositing in the lungs, accelerates the recruitment of macrophages, resulting in a tenfold decrease in the number of fibers remaining in the lung. The increased number of macrophages in the chrysotile/sanded joint exposure group was confirmed histologically, with this being the only exposure-related histological finding reported.
authors.affiliation: University of Edinburgh, ELEGI Colt Laboratory, Edinburgh, Scotland. davidb@itox.ch
authors.forename: D M
authors.initials: DM
authors.lastname: Bernstein
authors.forename: K
authors.initials: K
authors.lastname: Donaldson
authors.forename: U
authors.initials: U
authors.lastname: Decker
authors.forename: S
authors.initials: S
authors.lastname: Gaering
authors.forename: P
authors.initials: P
authors.lastname: Kunzendorf
authors.forename: J
authors.initials: J
authors.lastname: Chevalier
authors.forename: S E
authors.initials: SE
authors.lastname: Holm
mesh_terms: D000336:Aerosols; D000818:Animals; D017632:Asbestos, Serpentine / Q000493:pharmacokinetics* / Q000633:toxicity; D001273:Atmosphere Exposure Chambers; D001822:Body Burden; D003252:Construction Materials / Q000633:toxicity; D005240:Feasibility Studies; D019570:Inhalation Exposure; D008168:Lung / Q000187:drug effects / Q000378:metabolism* / Q000473:pathology; D008264:Macrophages / Q000187:drug effects / Q000473:pathology; D008297:Male; D019016:Mineral Fibers; D010316:Particle Size; D052638:Particulate Matter / Q000493:pharmacokinetics* / Q000633:toxicity; D051381:Rats; D017208:Rats, Wistar; D015203:Reproducibility of Results; D013997:Time Factors
chemical_list: D000336:Aerosols; D017632:Asbestos, Serpentine; D019016:Mineral Fibers; D052638:Particulate Matter
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