Evaluation of the deposition, translocation and pathological response of brake dust with and without added chrysotile in comparison to crocidolite asbestos following short-term inhalation: Interim results

Abstract

Chrysotile has been frequently used in the past in manufacturing brakes and continues to be used in brakes in many countries. This study was designed to provide an understanding of the biokinetics and potential toxicology following inhalation of brake dust following short term exposure in rats. The deposition, translocation and pathological response of brake dust derived from brake pads manufactured with chrysotile were evaluated in comparison to the amphibole, crocidolite asbestos. Rats were exposed by inhalation 6 h/day for 5 days to either brake dust obtained by sanding of brake-drums manufactured with chrysotile, a mixture of chrysotile and the brake dust or crocidolite asbestos. No significant pathological response was observed at any time point in either the brake dust or chrysotile/brake dust exposure groups. The long chrysotile fibers (>20 μm) cleared quickly with T(½) estimated as 30 and 33 days, respectively in the brake dust and the chrysotile/brake dust exposure groups. In contrast, the long crocidolite fibers had a T(½)>1000 days and initiated a rapid inflammatory response in the lung following exposure resulting in a 5-fold increase in fibrotic response within 91 days. These results provide support that brake dust derived from chrysotile containing brake drums would not initiate a pathological response in the lung following short term inhalation.

Türki̇ye’de Asbest Yasaği Ve Bazi İthal Ürünlerde Asbest Mi̇neralleri̇ni̇n Araştirilmasi

“…Asbest mineralleri Serpantin grubu ve amfibol grubu olmak üzere başlıca iki gruba ayrılmaktadır. Serpantin grubu asbestlerin beyaz, lifsi, yumuşak ve ipeksi yapıda olduğu ve kimyasal formülünün ise Mg 6 (Si 4 O 10 )(OH) 8 (krizotil minerali) olduğu bilinmekte olup kimyasal olarak da Si ve Mg elementlerini içermektedir. Buna karşın Amfibol grubu asbestlerin kimyasal bileşimlerinde Na-Fe-Si (krokidolit minerali), Na-Fe-Mg-Al-Si (ribekit minerali), Ca-Mg-Si (tremolit minerali) ve Ca-Mg-Fe-Si (aktinolit minerali) olduğu bilinmektedir.…”

“…Asbestin birçok ölümcül hastalığa neden olduğu bilinmektedir [2,5,6,7,8,9,10]. Bunlar; benign hastalıkları (parietal plavreda kalsifiye plaklar), paryetel plevrada hyalinize plaklar (kotsal, diafrağmatik ve mediastinal plevradai kronik fibröz plöretis vb.…”

Evaluation of the fate and pathological response in the lung and pleura of brake dust alone and in combination with added chrysotile compared to crocidolite asbestos following short-term inhalation exposure

“…All brake dust preparation took place at the RJ LeeGroup facility in a room equipped with an Aramsco Comanche® HEPA ventilation unit (Model 55011) with a nominal flowrate of 1800 cfm (50 m 3 /min). The brake dust was produced directly from asbestos-containing friction products (automotive drum brake shoes) by the RJ LeeGroup Ltd. (Monroeville, PA, USA) as described previously (Bernstein et al, 2014).…”

“…1 of Bernstein et al, 2014. All end points were analyzed for each group with the exception that lung digestion was not performed in the control group on Days 1, 2 and 7 in order to limit animal use.…”

“…In the interim results on the lung which were presented in Bernstein et al (2014), the brake dust from chrysotile containing brake drums was shown to produce no pathological response in the lung through 91 days following short-term exposure in rats. The study also demonstrated the importance of amphibole asbestos exposure in comparison to chrysotile in the etiology of asbestos related lung disease.…”