Document MgpDZEx5yRMZaNbqooJKwoJV

:'-i-f--Sia?;EH" AR226-2924 CENTRAL RESEARCH AND DEVELOPMENT DEPARTMENT HASKELL LABORATORY FOR TOXICOLOGY AND INDUSTRIAL MEDICINE THE EFFECT OF PARTICLE^ IZE ON THE ACUTE INHALATION TOXICITY OF Aft D Material Tested INTRODUCTION jsed in this study had been shown to be _____ __ extremely toxic by inha1ation"when tested as a highly respirable aerosol (ALC of 42 mg/m ). The purpose of the present study wasitodetermine theeffect of particle SAzeonthA inhalation toxicity of Two ^MBHIfl^HKj forms of the|H[M----ere tested; one was a 40% a^ieou^su^effffonaRd one was the pure niatenaT?1 For both materials. Approximate Lethal Concentrations (ALC's) were determined for various particle size atmospheres. The ALC was defined as the lowest atmospheric concentration tested which caused the death of 1 or more rats either on the day of exposure or within 14 days post exposure. Further, the relationship between expected pulmonary deposition (based on particle size) and mortality was investigated. PROCEDURES A. Animal Husbandry Young adult male Cri:CD(SD)BR rats were received from Charles River Breeding Laboratories, Kingston, New York. Each rat was assigned i; unique 6-digit identification'number which corresponded to a "umbered card affixed to the cage. Rats' tails and cage cards were color-coded with water-insoluble markers so that rats could be identified after exposure. Rats were housed singly in 5" x 11" x 7" suspended, steel-mesh cages in rooms targeted to have temperatures of 25 + 2C and 50 + 10% relative humidities on timer-controlled 12 hour/12 hour ligTrt/dark cycles. Rats were quarantined for one week prior to testing, and were weighed and observed twice during the quarantine period. Except during exposure, Purina Certified Rodent Chow ii'5002 and water were available ad libitum. Page 1 of 12 Company Sanitised. Dees not eonfain Tfifi& ("RE ww.^^;'a^;asa-^^5gg^^^s'B'^^< B. Exposure Protocol Groups of 6 rats, 8 to 9 weeks old and weighing between 224 and 297 grams, were restrained in perforated, stainless steel cylinders with conical nose pieces. Each group was exposed nose-only for a single, 4-hour period to an aerosol atmosphere of either the aqueous suspension or the. solid in air. Rats were weighed prior to exposure and observed for clinical signs during exposure. Surviving rats were weighed and observed daily for 14 days post exposure, weekends excluded except when deemed necessary by the rats' condition. C. Test Material Physical Form: Composition: iuspension' Aqueous suspension Purity: Contaminants: Synonym: Stability: ie test material was assumed to be stable throughout the exposure phase of the study. Physical Form: Purity: Contaminants: Synonym; Stability: lie test material was assumed to be stable throughout the exposure phase of the study. Based on the supplier's specifications, the test material was stable at the temperatures needed for generation. 0. Atmospheric Generation ifl usponsion Aerosol atmospheres of theUH^HBiHfXuspension were generated by pumping the liquid Tnto a Spraying SySrcms nebulizer. Air introduced at the nebulizer aerosolized the test material, and swept the aerosol stream through a cyclone elutriator and into the exposure chamber. Particle size distributions we.-e shifted toward Page 2 of 12 esRtpSHlf BsErfe@a. &U6& no esnfglR TS."A CB'i -^^;^?Q^^-:;g^Wi, :' ...::, s : -is .. ?^sss>j^.. ^S^S^&^&^.'^aBS^^S-a-W~yWs3fSffg. s- ;3,.-s..?.'- ;."; ^ y'^ia ;and ;'^'^^'"---I^'/'-'^-/JS^'>'^^'l^:'^"'.Mrf'<-?."'?.~K s^-.fe3 .r^,.a,,^.ES-!EaSia^i2afla^;-:fe^,ri-?^A..U ^ ^^*fl .^ ^ Sfe^ eposol atmosphi reNso^NaBereiyig,!e?r^ii matir^^^ifltota^prt^rtgS^ystain^inebu^aze^ '"-^&"!^^ i^^5^Sm"'i-iie^e';^ii:'^-?K.teSeu?-d;;;ai;^<-"'an'e-'sH8rss' -it.:, ;i mB-.rTycfai-i!'.w.-^; Bss^^^^.!g^a;a-:-^"---;,;aa.Mw"r"'i;'_.:'2-a^,.,Tffft;i'^;.is.s^'[!Ss'~^rs"-;^'! .s^ llla^.el.";'^.ffllfc-.^-l;u,^,uylai-.praW.'^.iff ^ ReaSe^l^oitAlll..^.^...,.-...^..-., fc.i.ar^.El,dSilWEl'-s.;-^fl " ?<rS5-q?!"*/-Bri!!s"_%.;---^C1.-.:*;?^Ssa^fesea.ff^Aie.ws-^B-n^-'ii;4- ^^-.joea';''^;: ^ ^^^^?: '^ --IrS^Ha^lcutIiii^lj----''2-^^'^^^^'^^^^53^^'^ .^^M^S1^^ y i^s'Cr^liuli^, iSiSIS-.iS.S-'Bi^SgMSe^;. ' r'7?,!;-"';-'-.-.- ;-;|Al-ii;-;iA' .l-^u-^s/.o?^.sauM:09:&gener;al3;c . A:S^"SSS-sS2Si-" ,^.--^3-^!S.-?gM^fe- ^ic^i^HtSaize'^fii^sffi^ .."NIBf^l^ ^s^i'^lfial A@|K'l@l"'ospher-ic concent.rat:'ipn3;o'|Spa1i3aj6u1aite^^-cli^rgiinJnfiBaiiifiS! -:pp^ia?nai|ly||l5- to SO-nilnute^iir^ei^slty^r^ingpfloNIi^ JiT^lierlgatmospriere through pre-w^ea^^s;''f1?ffejR^^ w^j|^re^]ghe;ciion a Cahn Model 26|gfijtcHBiai^^^troS^^ concentrataoniof particuiat;e wasMeteTO^^^e(iW^oms;th^%^a^r^ deRen1;3ia3^fore and after """ ^ . :. : DtHSiJrrgsSeachexposure, the pa1^ilie^a^distrtbutt6ffit^astiaef;ei^Jne(lW wlWla^gi-laScascade impactor.'"^^(t<%. for esiBliia^dNilosphenc concent 11 3y- W SffcSKSSISl-.vC', . . uiiik'wereijca^culated - from ..t.h. e t^o:.^tgaS, if3l'" --^, ;a Ti^iS^.,;a.~9 tinospt i e n. c c o" nWcri e.i n;.^t !;^! S^S?a^^^!%^'^i^^^ ^^i^5^^^^ partfcli^^jzlJJdata. Chamber te^i^^atll^fr^^mon^torod!'WT^ thermoiiieter'"Sduring each exposure.' ' ;i """": n^!!^;;'?![I:ijr:''t;!!fi| RESULTS. -;! Exposure,.Coiricijitions and Associated MoptaHtty !;;:s|i^ :'; ' ;'|:: :iH;?j1|t? ChanibettJI^emperaturrea.nged ." ;^ between I8-3^C during ex.p..o.s.u/^^isSff^ff'ilraiel!^ aqueousi!.suspension, and between 27-?35JGduring exposupesllt^nlSSolSci^tfl Wilde;-|em^al?e ranges are not expecSWfoP affect onil'"y , '. >t 'rWa'-S's.iWWif: exposur'e^ . .-- i.iEffKHss tULiifti^ ^Ss- '\s!Sfjsti -E.;a,ch,t|^g|jatinosphecorentaTned ^.d.i.sltrii.oution of Ra;ial])i^8i|M81 variflus'.^l^sg fssnSi:^ i. ncluding both snlaH t|s[naj|ljei'^than1. um^|a^^aRg^g|^|g||gt (Target um) 'particles.- "fne a^agrleometri^st^aaSaeli! fQreSch^Kc^e size distrtbution^was^^Mxiriiatelly^NSiiSl^StiowsM t o-ta,'j; ^?a,-t'>m.i ,o'KsW phen ,K-rit.'v . c c o . n c e n, t r a t i..o n , D a r ^ c ^ e y s ^ e -<!l;--*--,;aa,^=:.'^^;-.:.^ d-a-ii-s-t.^-'ifbK.u'-'fjigS-o^&n-i^"-<ni~a-^^s5is"o^-c^-^t-?a"i'fi:gi3a;1s;5 i'a^e(i.;.;rat^o^ta1ity for each exppsu^I'^BaMare g,^Ri|^^n^eJq)csu^s||j@ wilt^^^lllanllparticle size distrTbufions,.; JSe iricReffsiu^nSs^ineaalan8!^ aeRoayhann^^aineters indicate a smff''Tn the particle 'sa^zeSdaistraSut^on^ fron-.maniej^o larger particles. ' ss Palge'i^lja^-llill;! : LiSit' 'i' '^iMS^WSS^" eampany Sanitized. Doas RoieoRialh^eaaSt^ ^.^^^^^^iS^iii?!^^ ;;jm;; l|^^^^-:^^B;^;wg^a;a _ s^.a^a^!^l;i.^raa: ^:. t:. ^"'a^^i.^iiaHS^^-5^ ''^'ilSIJ@ffi^ '.''^^^KS^S^^'; a^liSfe^i^ S;.>;.3-:'<1-'^;'^ ^^^.igBpss^i:^:; ^ - , '"':'''^a^":''";;l'5-'^ ' '^i^il'1' ter^cSC^^il^Szat^or^n^^l^ili^ i|gp ^. .-. a.,S-.--!ste^.-_,-,y.a^..i..i..-! . .-.i-.^ ' -" ' .!;?^.:.'. .^. .^"A'. l^^te^i^^-j Tottfl Partl^uiiia^' C6ncen|i<^o" (fl'S ^dSSght ^^Maimc 1^ ()f Particliesg- ^ameter ^..^ffSlE"" '?? .iitJiS"'";..'.-- .-.a.'.ss a i-::^ .a--? ...a%^^i3SE-s.y;A?CT 16- + 6,6 42 T b 7.8 73 T 25 330 + 110 58 + 42 77 7 5.3 170 T 40 9.4 24 66 110 110 140 + 1.9 + 21 + 48 + 72 7 48 j^ 34 48 + 10 72 7 8.7 110 7 56 190 7 88 3207 56 390 7 100 520 j 140 57 + 18 84 + 31 190 + 33 360 7 33 610 + 82 620 + 42 ^'-'^fw m 3-1: -i--^- 73 ^r^ :!?: S95 79 fc 98- ^ :93 77 95 75 44 ' 76 45 18 . 86. 52 20 80; i'; ^ 51 22 H|j i i 87 76 68 98 93 81 98 93 77 99 96 83 92 76 53 98 89 62 67 50 34 78 52 32 73 50 29 88 60 26 89 55 27 77 48 22 79 54 28 57 29 10 70 43 23 63 39 19 74 46 22 71 41 18 75 42 17 21 30^ 21 8.1 3.0 4.% 2.3. - 1^- urn iii ....i6 um um ~7^-'" .;}.'? '"a .., 3^ um . 6|S um .' -5^8 um ,:.-6SO ~'. . 7^^ '" T''"-'-ft um 031^^? J-; :^ w 0^ .4%' 56 37 26 34 20 13 18 17 13 5.8 3.9 1.6 2,9 5.0 7.4 4.8 2.5 1.1 1.3 1U um fe.7 um 2.1 um 1.7 um 2.9 um 2.7 um 5.2 um 5.1 um 5.5 um 4.7 um .4.9 um 5.4 um 5.5 um 9.7 um 6.6 um 6.9 um 5.6 um 7.1 um 6.1 um 0/6 6/6 6/6 6/6 6/6 6/6 0/6 0/6 0/6 0/6 5/6 4/6 4/6 0/6 0/6 0/6 3/6 6/6; 6/6" , MNaesbsulmizeedrianandaercoydc-ylnoanme icwedreiamheeatteerd. during ? B. Estimated Lung Deposition and Associated Animal Mortality The fractional deposition of particles within the respiratory tract depends in part on the particles' aerodynamic sizes. However, literature sources vary widely in their estimates of the size-limits of particles able to be inhaled and to be deposited into various regions of the respiratory tract. Further, data indicate that deposition varies widely amoung individuals and amoung species. The Environmental Protection Agency has adopted the following criteria to define the approximate size-limits of particles which may deposit into the various regions of the human respiratory tract: particles smaller than 15 urn can be inspired and deposited throughout the resptratorjr tract; and p'artides smffTTer than 2.5-3.5 urn (nose arid mouth breathing, respectively) are expected to deposit predominantly in the alveolar region. Deposition of particles smaller than 3 urn is similar in rats and humans. Deposition data in rats for particles larger than 3 urn are not available. To investigate the relationship between the aliphatic carbamate toxicity and particle size, the following assumptions have been made: particles smaller than 3.1 urn will provide predominantly alveolar deposition, particles smaller than 13 urn (including particles <3.1 urn) represent total respirable parfciculate, and particles larger than 13 urn win not be inhaled. The 3.1 urn and 13 urn size-limits were chosen be-cause they are the experimental cut-points provided by the cascade impcictor used in these tests which most closely approach the EPA criteria. For each exposure, the atmospheric concentrations of particles smaller than 3.1 and 13 urn were estimated by multiplying the total atmospheric concentration by the mass percent of particules smaller than these cut-points. As shown in Table !, within groups of similar particle size atmospheres, mortality generally increased with increasing concentration. Further, as particle size distributions shifted towards larger particles, the concentration needed to cause death increased. The ourpose of back-calculating the atmospheric concentration of particles smaller than 13 and 3.1 urn was to investigate whether the apparent decrease in toxicity can be explained by the inability of a large fraction of these atmospheres to either be inhaled or be deposited in the alveolar region. For the aliphatic carbamate suspension exposures, the atmospheric concentration of particles smaller than 3,1 urn was most closely associated with animal mortality; regardless of total atmospheric concentration and MMD, as the concentration of particles smaller than 3.1 urn increased, mortality increased. For exposures to the solid, as the concentration of particles smaller than 3.1 urn increased from 32 to 58 mg/m , mortality increased. However, one exposure containing only 19 mg/m of particles smaller than 3.1 urn caused 6/6 deaths. The deaths at this concentration were unexpected, and the cause of death is difficult to explain. For both the aqueous suspension and tha solid, total Page 5 of 12 CawBany Sanitized. Boes nof eanfain TSftfi f.w - "^^l. eW . .. ,, . d, o^ ?.ep-raeesmpoa|tSreeJl (aM.i^ ationship l^. ti^ wiMe nwe(? ri a^ ^ ^ total resp-(pabTeiJjrt1cua1te Increased* a copresiond1ng Increase-ta , , , ^ - ^ ^ BOrtaltty was not observed. :;''tS?'^y:te..A.^':"'' '':'Nc?%^;", ::. Y^^Tab'le/H^ppesents the atlKfatiiwic^iaaU'^lon. o^llairttcles^.r saaller than 13 and 3.1 tm and^s^iKlatedjfrat.lplt^lii^^or^^ tfve exposures. Data for an exposuresSare presented 1n Appendix I. ^ Page 6 of 12 garepgh^ ggniffzed. 0@s rie^eaRfetn fe^Bi Table II Atmospheric Concentrations of Particles Smaller Than l3 arid~3.1 urn and Associated Rat MortalTt7 Atmospheric , Concentration (mg/m ]_ Mortality ^AqueouSsuspension) Particles smaller than 13 um: 66 0/6 42 3/6 140 4/6 72 6/6 Particles smaller than 3.1 urn: 15 0/6 33 3/6 37 4/6 56 6/6 (Solid) Particles smaller than 13 urn: 80 0/6 120 0/6 170 0/6 24 6/6 65 6/6 100 6/6 Particles smaller than 3.1 urn: 32 0/6 36 0/6 49 0/6 19 6/6 51 6/6 58 6/6 Data Calculated From 77 ing/in, @ 5.8 urn MMD 42 mg/m" 9 1.6 urn MMD 170 mg/m, @ 6.0 urn ?10 73 mg/m @ 1.9 urn MMD 77 mg/m3@ 5.8 urn MMD 42 mg/m" @ 1.6 urn MMD 170 mg/mm-, @L 6o.0u urn MnnMuD 73 mg/'mm " l@a 1^ .9" --urn M""M"D 110 mg/m3@ 5.5 urn MMD 190 mg/m" 0 6.9 urn MMD 190 mg/m, @ 4.7 urn MMd 24 mg/m, @ 1.7 urn MMD 66 mg/m, @ 2.1 urn MMD 110 mg/m 0 2.9 urn MMD 110 mg/m3@ 5.5 urn MMD 190 mg/m, <? 6.9 urn MMD 190 mg/m, @ 4.7 urn MMD 24 mg/m, @ 1.7 urn MMD 66 mg/m' @ 2.1 um MMD 110 nig/m @ 2.9 urn MMD Atmospheric concentrations were estimated by multiplying the tota1 atmospheric concentration by the percent by weight of particles smaller than 3.1 and 13 urn, respectively. Page 7 of 12 C. Clinical Observations In general, very '"ew clinical signs were observed In rats that survived exposure to the aliphatic carbamate (suspension or solid). During or immediately following both lethal and non-lethal exposures, some rats in several groups had test material on their faces and heads and had a diminished startle response. Most rats exposed to lethal concentrations had labored breathing, and a few rats exposed to lethal concentrations had red nasal and ocular discharges, ruffled fur, decreased activity and pallor. A few rats exposed to nnn-lethal concentrations had red nasal and ocular discharges. During the recovery period, most rats which survived exposure to either form of the test material had slight weight loss (less than 5<) for 1 day after exposure, and had no major clinical signs. However, a few rats had greater than 51 body weight loss, facial discharges, diarrhea, wet perineum, ruffled or discolored fur, hair loss and labored breathing. For the solid material exposures, most deaths occurred during exposure or 1 day post exposure, although a few rats died between 2 and 8 days post exposure. For exposures to the aqueous suspension, most deaths occurred from 1 to 2 days post exposure, with the latest death occurring 6 days post exposure. Rats that died lost approximately 7-151 of initial body weight 1 day after exposure,, and continued to lose weight until they died. Clinical signs for rats that died included labored breathing, facial discharges, limpness, ruffled or discolored fur, wet or stained perineum, diarrhea, pallor and lethargy. DISCUSSION ' ^i --^ ^ ii r^W^S Based on total atmasgpphheerrjclc^^coonncentraatti on, the Approximate Lethal Concentrations for botnVlmdj----lncreased frith increasing particle size: MMD ALC Aqueous Suspension Solid 1.6 urn 6.0 urn 1.' urn 5.6 urn 42 mg/m3 170 mg/nT 24 mg/m3 360 mg/m Although the soliixUmHmBHappeared to be more toxic than the aqueous suspensiorrTn the smaller parflcle size range, both materials were considered extremely toxic when administered as highly respirable aerosols. Page 8 of 12 'CQEHparijF anJHS@a. ess ^eS ecrifeh T3CA CS? "Bsa'w^ "" " --"-;-- VK^"y^'- y'l-fs;. ' rpf.y''''''^v'-'^^S3y^K^f"yet'^S^K^^^^^ When the particle size distribution was shifted toward larger particles, these materials were considered moderately to highly toxic. "Hie apparent decrease in toxicity with larger particle sizes is best explain^ by considering the fraction of the test atmosphere expected to deposit in the alveolar region. Regardless of total atmospheric concen tration, the concentration of particles smaller than 3.1 urn was most closely associated with mortality. Except for one exposure to the solid material, as the concentration of particles smaller than 3.1 urn increased, mortality increased. The cause of death in the outlying exposure to the solid material cannot be explained. In conclusion, uader_the conditions ,of this test, the Approximate Lethal Concentrations of theQ^------^BU|^1[suspensi on or solid) increased as particle size distribtinons^^We^Troffl^Hnaner to larger particles. Regardless of total atmospheric concentration, the atmospheric concent, -ation of particles expected to enter the alveolar region was most closely associated -i^ith mortality. However, one exposure to the solid material caused death at a much lower concentration than was expected, e-id the cause of death in this exposure can not be explained by this model. SUMMARY ^jBHBBBHBIIf^^ groups of 6 male Crl;CD*(SD)BR rats were exposed to aerosol atmospheres of as an aqueous suspension or as a solid for a singfe^Pnourpanod^uiWerent particle size distributions were generated to determine the effect of particle size on the toxicity of these materials. Further, the relationship between expected pulmonary deposition (based on particle size) and mortality was investigated. For both the aqueous suspension and the solid, the ALC increased with increasing particle size. For the^aqueous suspension, the ALC increased from 42 mg/m at 1.6 urn MMD,to 170 mg/m at 6.0 urn MMD, For the solid, the ALC increased from 24 mg/m at 1.7 urn MMD to 360 sag/ss at 5.6 urn ?10, For these materials, the fraction of the total test atmosphere expected to deposit in the alveolar region (particles smaller than 3.1 urn) was most closely associated with mortality. However, this relationship was unequivo cal only for the^flflugous_suspension exposures; one exposure to a low concentration oiBiHHHHH|tf)>3rtic1es smaller than 3.1 urn caused deaths which can not be expfamedTy^xpected pulmonary deposition. The atmospheric concentration of total respirable aerosol did not show a clear dose-response. Page 9 of 12 Seme&ny San^eO. a^ not eonfa?n TSCA cm C^1jCuTatim^lescribed In Sierra Instruments. Inc.. Bulletin 7-79-21-9IW. InsHmuctjibniJiJanual: Series 210 Ambient Cascade Impactors and Cyclone Presejitaratoi^ Air Qual^tyJSriteria for Partt cu1 ate. Matter and Sul fur Oxides. External RevlSwDlPatKSNo2., Office of Research andflevelopment, u. s. Environnient'aa Protection Agency, February, 1981. Date Issued: April 1, 1985 Number.of pages in this report: 12 Page 10 of 12 ^offipany BanHIzed!. Dass i-iSt ssrttasn TSCA CES ^--------. ..-. -.-. .,,-.-.. .^^y..,..- ,..,,..^,,.^^^,,,^g^^^^ Bl '".' " ' ' :-.-."^''-'^"s: '' . r.^i8^ :'y^vsv!'1~l''w. ' "'X M- -, T 'S: ";! Appendix I Atmospheric Concentrations of Particles Smailer 3.1 and 13 urn and Associated Rat Mortality 1-^^^>1 A.1|^^^^^^^^----Aoueous Suspension! 1. Concentration of particles smaller than 13 urn Than Atmospheric , Concentration (ing/in) 16 44 66 42 140 72 310 Mortality 0/6 0/6 0/6 3/6 4/6 6/6 6/6 Data Calculated From: 16 mg/m3@ 1.7 urn HMD 58 mg/ili- @ 6.6 um MHD 77 ing/m" 9 5.8 um HMD 42 mg/m3@ 1.6 um MMD 170 mg/m @ 6.0 um MMD 73 mg/m3@ 1.9 um MMD 330 mg/m @ 3.4 um MMD 2. Concentration of particles smaller than 3.1 urn Atmospheric , Concentration (mg/m ) Mortality Data Calculated From: 10 0/6 58 mg/ffi3@ 6.6 um MMD 12 0/6 16 mg/m- @ 1.7 um MMD 15 0/6 77 mg/m @ 5.8 um MMD 33 3/6 42 mg/m3@ 1.6 um MMD 37 4/6 170 mg/m- @ 6.0 um MMD 56 6/6 ^ 150 6/6 6-\------^------------H^olld^ 73 mg/m3@ 1.9 um MMD 330 mg/ns @ 3.4 us KKD 1. Concentration of particles smaller than 13 urn Atmospheric , Concentration (ing/in ) 8.2 32 32 56 59 80 120 170 Mortality ' 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 Data Calculated From 9.4 mg/m3@ 1.1 um MMD 48 sng/m, @ 5.2 UR! MMD 57 mg/m- @ 9.7 um MMD 72 mg/m, @ 5.1 um MMD 84 mg/m, @ 6.6 um MMD 110 mg/m, @ 5.5 um MMD 190 mg/m, @ 6.9 um MMD 190 mg/m @ 4.7 um MMO Page 11 of 12 iGompany Sanitized. Does not contain TSCA CBI A. is^^ijp'.-^-a^p^?^^ ' ''',' ',.-. '"^Kf^-1 's.^'-'"^ Appendix I (cont'd) Atmospheric Concentrations of Particles Smaller Than 3.1 and 13 urn and Associated Rat MortalTt7 B.lfjcont'd) 1. Concantratlon of particles smaller than 13 urn (cont'd) 24 65 100 110 140 270 280 300 390 410 430 460 820 6/6 24 rng/m39 1.7 urn HMD 6/6 66 mg/m:' 9 2.1 urn HMD 6/6 110 (ng/m, 9 2.9 urn HMD 6/6 110 ing/m- 9 1.7 urn HMD 6/6 140 mg/m, @ 2.7 um HMD 3/6 360 ing/ill' 9 5.6 urn HMD 5/6 320 ing/in:, 9 4.9 inn MMD 4/6 390 ing/in- 9 5.4 urn MMD 6/6 400 ing/in- 9 2.5 urn MMD 4/6 520 mg/ni' @ 5,5 uin MMD 6/6 610 ing/in, @ 7.1 urn MMD 6/6 620 mg/m, @ 6.1 urn MMD 6/6 900 ing/in 9 2.6 urn MMD 2. Concentration of Particles Smaller than 3.1 urn Atmospheric , Concentration (ing/in ) 5.7 6.4 16 19 23 32 36 49 19 51 58 79 86 86 87 91 110 110 150 260 570 Mortality 0/6 0/6 0/6 0/6 0/6 0/6 0/6 0/6 6/6 6/6 6/6 3/6 5/6 4/6 6/6 6/6 6/6 6/6 4/6 6/6 6/6 Data Calculated From 57 ing/in3@ 9.7 um MMD 9.4 ing/in:, @ 1.1 um MMD 48 ing/in- @ 5.2 um MMD. 84 mg/m. 9 6.6 um MMD 72 mg/m- 9 5.1 um MMD 110 mg/fB" @ 5.5 urn MMD 190 mg/m:, 9 6.9 um MMD 190 mg/m" @ 4.7 um MMD 24 mg/m3@ 1.7 um MMD 66 mg/m- @ 2.1 um MMD 110 mg/m, @ 2.9 um MMD 360 mg/m, @ 5.6 um MMD 320 mg/m- 9 4.4 um MMD 390 mg/m' @ 5.4 um MMD 140 nig/re- @ 2.7 um MMD 110 mg/m, @ 1.7 um MMD 610 mg/m" @ 7.1 um MMD 620 mg/m, @ 6.1 um MMD 520 mg/m, 9 5.5 um MMD 400 mg/m:3@ 2.5 um MMD 900 mg/m @ 2.6 um MMD Page 12 of 12