Document X74nQgGej5Q4Rg1oDExGn8Z4

c r composition of tho raw baU^Ufl la shown In tabid* Z and 3. Pefcrogrephto and X-ray dlffreetlcn examination of atBOSpherlc dust, collected In tho dust room with an electrostatto preolpltator aftar tho installation of wire brushes. Indicated that about 15 per cant of tho air-eusponded notorial was ehrysotllo and about 60 par ot} aarpanttosi of tho balanco magnetite comprised 10 par oent, bruolto S por cent, quarts 2 par osnt and other minarala 10 por oont. During tho ?ewth period before tho wire brusboe wore used tho chryootllo oontont of tho atmospheric duet was aooishtt lower than 16 por cent but rollablo Tsljfco, woro not nbtatnod, Tlio dust concentration for tho first 7 souths of tho experiment was about 100 million particles por aublo foot of air* After , tho wire bruahos were Installed, tho duet oounta wore higher and the overall averace for the remaining 21 montha waa about 150 million. Slxo- ^ & frequency studies of dtraosphorlo dust eolleoted inside tho animal cag^x revealed that nearly $9 per coat of tho eompoaoute suspeadod la tho air could bo elasslflod ao olumpo or parttolesj only about l to 1*5 por oent was fibers* One-third to - one-half of tho flbora wore longer than 10 wtorono, indicating a concentration of long fibers of about 0.0 million, ml* figure to sohoxoMuthaorxnxeu-uhBaXirEotchxeasepsfiXtimaxastuecdx^aluo of 1.1 million for tho short-fiber experiment. Guinea pigs, rats and mice were used in the inhalation expari&ant with the 1Q0 por cent ball-milled soboetos duet. The results ere eunsarlced^ in tohlo 9. Benetton In Guinea Mgs* The experiment was started with 100 gulsea *tfe. As tho dust exposure procooded, thoro were S3 aooldental deaths. 24-