Document be623Owbpq8zOpo6bK319RNy

,'t June l'M S A J'WiaWAI Ilf I.AWMATUaV- ANO Ct.Pt CAI. Mi H< M l-XPt RIMFNTAI. STUDIO (IN- ASBKSTTK S TQ(H 203 Ml ni! i Mm m. fli /mrnm nr #/ PfirurfMcy. I'nivrruiv SirHmhn* h \n.* iin- i*uMi*limrfH * the Pnrunwscontosis Research I mi m loh.mnr'hii(! in ftSJ. iniNiKJlKWs hatt hem mull n l axifljin whether pulmonary Icviom and .>mpiK.inn% following the inhalation of crocnlolrtf and .rii<<Mn' i!iih|\ c similar to those awsuitnl with es* |s>Min to khiysotile hist.' the results imhilnl that iii*itloiiif ami annisite dusts essentially caused an inter* *iimI hhfosis. this was sem to he perthronehioiar and pensasctilar in distnhutton during the early stages, and in the later stages the lesions became diffuse, with aWrotar ss.ill thickening and peribronchiolar and perivascular IlhfOMV Other clinical investigations suggest that asbestos may he implicated in the development of malignant tumours of the pleurae, and primary neoplasms of this nature have been described by many authors in recent years.!* The pathological evidence associating these tumours vMih asbestos appeared to be inconchisrve. Wagner.' how* wer. reported that 47 cases of mesothelioma had been ulentified in South Africa up to the end of June ItoD. In < .f these a possible association with exposure to crocido* Me from the Northern Cape has hem established. Whether the primary factor in the development of these tumours it csfsiMire to asbestos dust, or to a contaminant of it. is as yet not known. According In Wagner, one would expect similar cases from the Lydenburg district, since the nature f the rock, ore and fibre, are almost identical with those *f the Northern Cape. Attempts to produce tumours in espcrimental animals hv cspusinB them to an atmosphere of asbestos dust or to intratracheal injection of asbestos have hem disappoint* mr.'" Vnrwald rt mfound that ordinary indusinal j\K*sim ilust ami Iona fibres from which the small nartiefes had been separated tae peribronchiolar fibrosis. With dust particles J or less there was little or no reaction In expert* mental animals. Behrens'* also reported that pure chrysintile ashestm injected intranerrtonealty into mice and intratra* chrally into rats produced only a nnn*spaciflc fibrosis that micht be due to a foreign-body reaction. At present no evidence is available regarding the pathogenicity of croci* ifohte in experimental animats, although clinical reports incriminate cmcidolfte as a pnesiMa aethdogical factor Ht the development of malignant tumours ht tha hmg of humans. The present preliminary study was therefore Named to investigate the iwthogenicity of crocklofite and a mixture of croeidofMe and quart* ht the lungs of rata. rua i. war oturaiaunow iw remnn nr mnrtoauiv aw* gusare 1 fWlwwffy Qmmt ^ J4 * 2*4 /4 an an .*> 10 to 90 90 Msrrauut ami mkimoou Hmu Samples of very pure rock crystal fquartr) and *1 - .'C.;nM| Imm lbk Department of Geology. University *f 'iuBcntvnch-l asbestos fibres were nutated, cut up as finely as |nsi and ground for several days, the rock crystal was crus and also ground ht an agile ball mill the sire dtsir, thm of the particles is given in Tabic I. A mixture TAatg n. tin mu m ammvxm ne ivrenm. tfmm Vimteai't SSh. FCfO. FeO MfO 91 to 0 1X44 tel* 1*17 (aO Na/I Hd>* M,0~ Totat ` 0I` .0*0o-o to 2 5 rarnr . " ' - ****** quaftt and asbestos was prepared ht iMRprwpaeda* 25:75. The chemical composition of the cmcidnfite esfw is given-htTaMel!- ------ - ^rr 4dmb. Albino' rata (fforrwt norurffcwi^Wlsiatf^lr lute) weighing 150-175 G. were used^Twojgruupwof animals each were htjected intratracheally whh smpenu of asbestos and a mixture-of quarts-and eshestowresj lively. . flee Mipemkm*. Tbe dusts were suspended in ft saline in the proportion of VI mg. of dust per I ml. I samples of each of the dusts were weighed out m s.r capped bottles. 20 ml. of saline added, and tbe wnpen stenlired by autoclaving for 20 minutes at 15-fb. press Tbe suspensions were shaken before use. htfrrtum nf </t/v. The an mals were lightly enae Jhct whh ether. They were tied on their hecks u a sl*i dissecting hoard ti 49 I. the limguc retracted wnh a a speculum introduced through the mouth into tha thr and tha head: drawn forward and downward, unot chords were vMMa. A I6*gaugc Muni huBosr needV Inches tong, was then inserted into tha trschaa; a syr containing I ml. of suspension and f ml. of air quickly attached and the suspension injected forcibly the hints. Dmmkm nf nprWrrrni. Tbe espenments lasted days and one rat out of each group was killed at in intervals. A few animals died and had to he discarded. Iffiftdogfruf Mrftefqm. The animals twe anaedhet with ether, the trachea csponsl. and lit ml of formnl-saltne injected into the lungs by inserting a %vi nenfie into the trachea. I he trachcas were then tnd tha animals autopsied. and the unopcncsl tuners purees 15". formof-saline. After flsalion. the lungs were seen in a sagntal plane near the hilum and whole lung hi were embedded in paraffin wax. Serai sections n thickness were cut from each Mock. Of these, two stained with hacmatoxylin and cosin and another im natfd with silver (Gordon and Sweet"). Tbe rema sections were kept as spates. Grading* The grading of the maturity and swem the lesions was done according to tha new system of f* *1 t sx follows*