Document 0JJbKLawOjr6L4MnErXDOZOnx

AR226-3380 SSS^SSSSWSWS^S^^wwaw'iw.-i Perfluorooctanoic Acid: Relationship Between Repeated Inhalation Exposures and Plasm Concentration in the Rat P. M. Hinderliter, M. P. DeLorme, and G. W. Jepson The DuPont Company, Haskell Laboratory/or Health and Environmental Sciences, Newark, Delaware, USA fllfAbstract ^Results -- Singe Exposure Phannacokinetics f Results -- R A large pharmacokinetic database exists describing ^r behavior ofpcrfluorooclanoic acid (PFQA) following oral otposure. Tlie objective of this study was to quantify plasma PFOA conceiilraiions, far (lie purpose ofbridging the oral and inlialation exposure daia sets. The study was comprised of two separate experiments: Phase I consisted of BSingteG-lxmr nose only exposure while Phase II consisted of repealed exposures (6 hours per day. S days per week for Ihree week!,). In botti expcrimenis, ma!e and female rats were exposed nose only to an aqueous aeioEotof 0,1, lO.orZSmD/m'PFOA. Levels were selected to produce bloodwasdrawn via liieiail vein pre-expQsuie, during exposure at 0.5.1,3 ami 6 hours. and post-exposure at 1,3.6. 12, 18 and 24 hours, Rais were noi removed fioiii ihe exposure chamber during tlie exposure pcrioil and blood was taken from the (ail vein wliiie the animals remained in ilie nose-only reslramcrs attached 10 the exposure chamber. For Phase IIi blood was collected immediately before and after the daily inhalation exposure period three days per week. Piasma derived from the whole blood samples was analyzed by liquid chromaiographyinass spcctromeiry (LC-MS). PFOA appears rapidly in the blood of botli inale and female rats exposed via lh; inhalation route. PFOA elimination is sex-dependent, with female rais eliminating PFOA ftom die to tile aimosplieric exposure concentrations from I 10 25 mg/m1. Repealed daily inhalation exposures produce little plasma carryover in female rais, but significant carryover in male rats. Male mis reach a steady staie plasma concentration by three weeks with plasma conccninilions of 8,21, and 36 ^g/mL respectively when exposed to 1.10, and 25 iiig/nl3 PFOA. Female rats readied post exposure plasma concentrations of 1,2, and 4 f^g/mL respectively when exposed lo f, 10. and 35 mg/m3 PPOA but relumed 10 baseline levels for tlic pre-exposure time points. This study provides (he data necessary to relate cutemal atmospheric concentrations of PFOA to PFOA levels in male and female rat plasma. This research was sponsoredby the Association of Plastics Manufacturers in Eiiropc (APME) Fluoropolymers Coinminee, 101Materials and Methods Lin6arperfhiorooctanoicacid<PFOA) was obtained from Aldrich Chemicals. Since this sludy utilized Ihe inhalation route of exposure, no attempt was made to establish the actual dose each rat received and all results were itaercfore reported as a [unction of tlic group exposure coHccnltaiion(s)rai]ierlhan a function of dose- Male and female C^!;CDe(SD)IGS BR rais were obtained from Charles River Laboratories, Ine,, Raleigh, North Carolina. At the lime of exposure, rats were approximately 6-8 weeks of age and Ilie weight variation did nol exceed 20% of ihe mean weight by exposure group. Ail exposure chambers wcteconsirucicd of stainless Steel and glass <NYU style) wilh a nominal inlernal volume of ISO L with a dispersion plate inside the chamber to promote uniform chamber distribulion of the test atmosphere, Animals were individually restrained in polycarbonate {Phase 1) or perforated stainless sicel cylinders (Phase II) with conical nose pieces. During exposure, tlie animals were kept warm willi a heat lamp (Figure I). A 5% <wcighi/weighi) solution was prepared and adjusted lo a pH of 6.0 to B.C. Clianiber Spraying Systems nebulizer. Tlie puinp and flow controller were controHed and monitored by the Camile Inhalation Toxicology Automated Data System (CITADS). Chamber using diluiional air. The atmospheric concentration of PFOA was deienniiied by gravimetric analysis al approximately 60-minuie intervals during each exposure. In order lo tieicmnne if the gravinielric analytical method used 10 quanliiate tlie airborne test subsiance conccmration included the lest substance plus waler. air samples were taken nom cliamber atmospheres that ranged from 1 to 25 mg/m' teEl substance, The filters were weighed, The fillers lost <0.03'% of their mass, indicating thai tlie filter reflected Ihe total rnflss of suspended aerosol in ihe exposiite chambers. chamber at least once per week during (he Phase II study wilh a Siena8 Series 210 cyclone ptescparator/Cascodcimpacior and Sierra" series 110 constant flow air sampler. Cliamber airflow was set to achieve al least 10 air changes per liour and was monitored continually, 'M to 60%. and 19%, respectively. Airflow, leinpcrature. and relative humidity were monitored coniinuously and recorded ni 15-minute intervals. Chamber oxygen conceinraiion was recorded twice during cacil exposure Plasma samples were processed by protein precipitation (PPT) using Isolule Array prolcin precipitation columns (Argonaut Technologies, Foster City. CA), A 0.5 (;g/ml solution of pernuorononanoie acid (Aldrich Cliemicals) in ACN was used as an internal standard. Plasma samples were tliawed, and a 20 fiL aliquot of cacti sample was applied 10 the PPT ACN/intemal standard solution. Dilution rates, ranging from 1:4 (oOfiLof internal standard solution) lo 1:50 (9BO(iL of internal standard soluiion), were utilized in order to capture the sample concentrations withitt me range of the standard curve conccntraiions. "Die array was slowly clulcd under vacuum into a ofrwell receiver plate, ccmrifuged at -3000 rprn for m Experimental Design Phase 1 (Single Exposure) To detcnnine the proper exposure ooncenliaiions for Phase 11, four groupsof 3 male 1 nig/m3,10 mg/m1. or 25 nig/m'1. A conirol group of rats was exposed to air only. Blood was collected via the tail vem and was drawn pre-expOEUte, during exposure at 0.5, 1,3 and 6 hours, and post-exposure at 1.3,6,12. 18 and 2d hours. Individual collection. Rats were 1101 removed from tlie exposure chamber during llie exposure sioredonwcticc. Plasma was separated by cenlrifugation. Rats were sacrificed following the final blood collection Plasma derived from the whole btood samples was analyzed by LC-MS. Tile exposure concentrations selected for Phase n were levels that produced plasma conceniratioBS similar to plasma concentrations observed in a previous study of oral gavage dosing in rats.'" After the exposure levels wcie selected, four groups of S male and 5 female rats each were exposed (nose only) for a 6-lttur period. S days per week (weekends excluded). for 3 weeks lo an aerosol of llie lest substance. The starting lime of me exposure is into the exposure chamber. The exposure end lime is defined as ilie lime wlien me nose only resirainers arc leinovedlrom tlie chamber. After each exposure, rals weis returned lo llieir cages. Thecontrol groupofratswascxpoEedio aironly. Exposure tune for blood collection. As in Phase I, blood was collected via the lail vein. Blood was collected before and after Ihe daily inhalation exposure period three days per week. Rats were sacrificed following the final blood colleclion. 4-- Simiy Hours --25 nig/in3 -a-10 rug/in3 -&-1 mg/m3 -N-Omg/rrr1 Figure 2: Plasma PFOA Concentraiion following a single 6 hour inhalation exposure Phase I (Single Exposure ^Results - Chamber Conditions CHAMBER CONCENTRATIONS OP PFOA Design Conocninillon 1 10 25 Measured Conccniralian* (lHE/in'1 1.2 O.iB 0.66- 1.7 6 9.B 0.5B 9.0- 11 6 27 31 24.32 6 of llie values obtaineil from 1 cxposuic. Concnilnilion I dne/ia1) I 1 0.04 O.SI-1.3 IS 11 Viilucs rcprestnl the mcim. slawlard nrot oflliennain (S.E M.), PHASE 11(REPEATED EXPOSURE) PARTICLE SIZE DISTRIBUTION O? PFOA Dtsfen (niE/m>> 10 25 MaiS Median Gcnniriric Aerodynamic Standard DianiHcrdim) Dcvlmion % Particle <lBin 18 33 15 <3linl<10nm SS 100 87 100 S3 100 maleorleina c rats as (lie plasma urvcs are parallel on a log scale. For the setl for Phase II of ihe study, male and female C C^ compared to oral gavage sludy of PFOA.ir This study ex gavage doses from0.l"l^25 ngPFOA/kg body weight. The values for th. from 0.598 lo 160,0 |igAnL(nale and 0.67 lo 132-7 (female). Because ilie C Phase 1 fell w thin Ihe middle of !b were noichangedfor Phase 11- ^n (".e'."-) .,, 1 SclulscUomWty MOI,! S.D. R"-. " Hi. S.D. RK.K ii Mc"" s^l 15 1.2 23 - n 2B 25 ! S 32 - 26 30 24 0.93 31 -'25 32 TO 003 Rt"" " 70 2B ^<SD1.^ cj^,. 25 25 24 Temper CO 016 a09 ooa ,.r lU,,,f,,)4 5 ^ H ;; 24-26 34.26 28 0066 28 70 0014 70 23-14 f-Umncipoiun-s Phase II plasma concen five days per eck, with p third and fifth exposure d following repealed expos of PFOA in llie plasma. T of the sampled exposiircd slate value is approximate Phase I, repealed exposur FEacli a steady slate plasm of B, 21, and 36 jig/mL re rais reached post-exposur B Conclusio rouic. PFOA elimiaatioti is plasma much more efficicn mg/m'. PFOA plasma conc concenlralion by llircc wee respectively for the !, 10. a