The pathological response and translocation of a commercial chrysotile product similar to that which was used through the mid-1970s in a joint compound intended for sealing the interface between adjacent wall boards was evaluated in comparison to amosite asbestos. This study was unique in that it
presents a combined real-world exposure and was the first study to investigate whether there were differences between chrysotile and amosite asbestos fibers in time course, size distribution, and pathological response in the pleural cavity. Rats were exposed by inhalation 6 h/day for 5 days to either sanded joint compound consisting of both chrysotile fibers and sanded joint compound particles (CSP) or amosite asbestos. Subgroups were examined through 1-year postexposure. No pathological response was observed at any time point in the CSP-exposure group. The long chrysotile fibers (L > 20 tory μm) response cleared occurred rapidly (Tin 1/2 the of 4.5 lung days) following and were exposure not observed to amosite in the resulting pleural in cavity. Wagner In contrast, grade 4 interstitial a rapid inflammafibrosis within 28 days. Long amosite postexposure. By 90 days the fibers long amosite had a T1/2 fibers > 1000 were days associated and were with observed a marked in the inflammatory pleural cavity response within on 7 days the parietal pleural. This study provides support that CSP following inhalation
would not initiate an inflammatory response in the lung, and that the chrysotile fibers present do not migrate to, or cause an inflammatory response in the pleural cavity, the site of mesothelioma formation.