Document 9LQqOpOr728m3ynQ0Q4L7vE6L

BIOCONCENTRATION TEST SUBSTANCE Identity:Perfluorooctanoiaccid,ammonium salt;may also be referredtoas PFOA ammonium salt,Ammonium perfluorooctanoateP,FO, FC116, FC-1 26, FC-169, or FC-143. (Octanoicacid,pentadecafluoro,ammonium salt,CAS # 3825-26-1) Remarks: The testsample isFC-143. It'psuritywas not sufficiently ,characterizetdh,ough currentinformationindicatesitisa mixtureof96.5 100% testsubstance and 0 - 3.5% C6, C7, and Cg perfluoroanalogue compounds. The 3M productionlotnumber 377. METHOD: Method/guideline followed:3M derivedpreliminaryinvestigatioonutlinedin the TechnicalReport Summary. Investigatioinncludedmethod development forthe analysisoffluoridbey combustion. Type: Staticexposure withstaticlearancephase. GLP (Y/N): No Year: 1995 Species: Fathead minnow (Pimephalespromelas) Supplier: AquaticBiosystems,Inc.F,ortCollinsC,O. Analyticalmonitoring: Whole fishand testsolutionwsere combusted ina modifiedorganichalideanalyzer(Dohrmann DX-2000).F-activitiyncollection fluidwas then measured withan ion-selectiveelectrodeconnected toan Orion Research ionanalyzer.The concentrationofPFO was then calculated from the F-ionconcentration. Length and weight: Not noted inthe report. Uptake period: 13 days Depuration period:15 days Statisticamlethods: One-way analysisofvarianceand Tukey's HSD test (alpha= 0.05)were used tocompare theaverage concentrationsof PFO in tissuesfrom PFO-exposed fishduringthe uptake and depurationexperiment. Test fishage: 64 days Loading: 124.6 + 20 mg fish(wetwt.)per litetrestsolution. Pretreatment: Not noted. Test conditions: Dilutionwater: Caton-filteredwellwaterfrom 3M Well *2, St.Paul, MN Dilutionwater chemistry: hardness: alkalinity: pH: 272 + 8 mg/L as CaC03 232 + 8 mg/L as CaC03 8.5+0.1 Conductivity:510 + 14 pmhos/cm Dissolvedoxygen: 8.5+ 0.3mg/L Stockand testsolutiopnreparationT:he primarystocksolutiownas prepared by dissolvingsolidPFO indilutiownater to create a 1000 mg/L concentration.The nominal concentrationof 25 mg/L was obtained by dilutinagn aliquotof the stock solutionto 15 literussing dilutionwater. Exposure vessels: 5 galloncylindricahligh densitypolyethylenetanks containing15 literosftestsolution. Number of replicates:One Number of fish per replicate:30. Number of concentrations: One plusblank control Water chemistry during the study: Dissolved oxygen: The DO concentrationof the control dropped below 6.0 mg/L at 72 hours afterthe startof the test. Aerationwas initiateadt thispointand continued throughoutthe testto maintain DO levelsat or near 100% saturation. Test temperature: 20+1 OC Average pH (controland testsolutions): 8.2 + 0.2 Photoperiod: 16 hours lightand 8 hours dark. Feeding: Fish were fed livebrineshrimp every 48-hours beginning 24hours afterstartingthe test. Sampling: Five fishwere removed from each tank at 192 and 312 hours during the uptake phase and again 24, 96, 168, and 360 hours afterbeing transferredto clean dilutiownater. Remarks field:Fecal material/ excess food was removed from tanks as needed. DO measurements were taken daily.Test solutionpH was measured once more at the end of each experimentalphase. RESULTS ConcentrationofPFO measured intestsolutions. Phase Solution UPTAKE PhaseTime (hours)* AveragePFO Concentration (ug/mL) Standard Deviation Control 0 <1 192 <1 312 <1 - 25 ug/mL PFO 0 25.0 1.8 192 25.5 2.2 312 25.9 1.8 DEPURATION Controlclearancetank 0 <1 - solution 168 <1 360 Not available 25 ug/mL PFO exposed 0 <1 clearancetank 168 <1 - 1 360 Not available *Elapsed time(hours)fromthe beginningofeach experimentalphase. Average concentration of PFO (measured as F-) in Pimephales promelas tissues Time (Hours) PFO inFish pg/g Standard Comparison Of wet weight Deviation Means 0 1.7 0.4 c 192- 44.7 -9.1 A 312 46.7 5.8 A 336(24)- 19.9 5.1 B 408(96) 7.6 1.3 c 480(168) 7.6 E5== c 672(360) 8.0 1.6 c Number in()indicateeslapsedtime(hoursf)rombeginninogfdepurationphase Means withthesame lettearrenotsignificandtilfyferenatalpha= 0.05by the Tukey-Kramer HonestSignificaDnitfferencteest. The calculated312 hour BCF forPFO is1.8usingthe equationBCF Ca/ C, whereCa istheequilibrciounmcentratoifotnhetesstubstancienthefisahnd Cw isthe equilibriucmoncentrationofthe testsubstance inthewater towhich the organism isexposed. CONCLUSIONS No definitivceonclusionscan be derivedfrom thisstudy. General observationscan be made. PFO concentrationsincreasedinthefishtissuesover the course ofexposure. The PFO infishtissueappeared tobe directlryelatedtothe concentrationof PFO inthe testsolution. While concentrationsdecreased inthe whole fishsamples over the periodof the clearancephase, the timerequiredforcomplete removal islongerthan the 15 days used inthe test. The concentrationof PFO intestsolutionsremained constantduringthe static exposure experiment. Relativetothe controltreatment,thesurvivaland growth ofthetestfish exposed to PFO were not adverselyaffectedduringthe experiment. Submifter: 3M Company, EnvironmentalLaboratory,P.O. Box 33331, St. Paul,Minnesota,55133 DATA QUALITY ReliabilityK:limischranking2. Thisstudy meets thecriterifaorquality testingh,owever, therewas no definitivaenalysisofthe compound ineither thefishorthe testsolutions.Itwas measured indirectlays F-ion.This would notallowforthe determinationofdegradationormetabolism byproductsand couldyieldfalselyhighreadings.There was alsono consideratiofnorthe possibilithyatthe testsubstance may have been soted tothe surfaceofthe fishratherthan residingintemallyt,huspossiblyoverestimatingthe BCF. The studylackscharacterizatioonfthe testsubstance purity. Thirdpartyreviewby Dr.John Giesy of Giesy Ecotoxicology,Inc. (observationsincludedwithreport)verifietshe studiesstrengthsand weaknesses. REFERENCES 3M TechnicalReport "Assessment ofthe BioaccumulativePropertiesof Ammonium PerfluorooctanateS:tatic"R.D. Howell,J.D.Johnson, J.B.Drake, R.D. Youngbiom, May 31, 1995 3M requestedexpertoverview,"BioaccumulativePropertiesofAmmonium PerfluorooctanoateS:taticFishTest",Dr.John P. Geisy ofGeisy Ecotoxicology,Inc.,March 20, 1995 i I OTHER Last changed: 5/24/00 Te,bhnicalflep'ort Summary To: Patent& Technical Communications Services-201-2C-12 RepoitSunmaiy mustbe OW*7&on. Gukkfn"amoniovorso*Fdo. Document DopmUnM Nuff" Number: 10222 TO D. L.BACON Au#W(S) R. D. HOWELL, J.D. JOHNSON, OWdWVD"wtn" po Numbw J. B. DRAKE, R. D. YOUNGBLOM PAW 06AVON OAA CAbb-=M.-WW Do" TYPW 05/31/95 Empiwi- Nu"6wA 295864/ 7288 ENVIRONMENTAL TECHNOLOGY pnod D-W"- METHOD DEVELOPMENT Repw Tkm & SERVICES Assessment ofthe BioaccumulativePropertieosfAmmonium K*yworcis 01 089 Perw C4vorw Perfluorooctar%aSttea:tic MayIO94-MaylgO BioaccumulationA;ffwwnium perfluorooetanoatfei;sh;statifcishtest ProjectObjective& Repon Abstrwt Proceduresaredescribedthatwere used forobtaininglaboratordyataforthegptakeand depumtion ofammonium perfluorooctanoat(ePFO) by thefatheadminnow, Pimephales promelas,from dilutiownater usinga statiecxposure technique.These procedureswere intendedtoprovidebackground informatioonn thebloaccumulatioonf PFO inflsh. Report Type Security Webook FWwance R & D Research and Development 13 P]LotPlant [3 MANufacturing [3 Management SUMmary [3 Open Reportand Summary 0 [3 TRP Tripor FieldRepoft 0 FACtDryExperiment 0 ENGirwadng [3 ROI Record of lnvandon [3 TECH. Service [3 GOVL Pwied [3 OTHER Closed Report-Open Summary 3M ChomkW 0 Now ChemicalsReporbd Registry L,.f.r.am b.u tokoft ForP & TCS Use Onir. ffreportisPiintedon bothsidesofpaper,send two copiestoP A TCS. ASSESSMENT OF THE BIOACCUMUTATIVE PROPERTIES OF AMMONIUM PERFLUOROOCTANOATE: STATIC FISH TEST ABSTRACT: Procedures are described that were used for obtaining laboratory data for the uptake and depuration of ammonium perfluorooctanoate (PFO) by the fathead minnow, Pimephales px-omelas, from dilution water using a static exposure technique. These procedures were intended to provide background information on the bioaccumulation of PFO in fish. ORJRRTI_VES: To accomplish a preliminary investigation of PFO uptake and depuration in fish. This investigation included method development for analysis of fluorine by combustion. METHODS: Summary of Practice The uptake and depuration test was conducted using a static (test solutions were not renewed) exposure system. During the uptake phase of the experiment, fish were exposed for 13 days to dilution water to which a selected concentration of PFO had been added. Following the uptake phase, fish were transferred to dilution water which did not contain added PFO for a 15 day depuration phase. A control treatment, in which fish were exposed to dilution water to which PFO had not been added, was included with the test. The control provided a measure of the acceptability of the test by giving an indication of the quality of the test fish, and the suitability of the dilution water, food, test conditions, and handling procedures. During both phases of the experiment, fish and water samples were removed periodically from test chambers and analyzed for PFO. Apparatus Facilities - All fish tests were conducted at the 3m Environmental Laboratory in St. Paul, MN. Proper test conditions (temperature, photoperiod, and ventilation) were maintained with the use of a controlled environment chamber (REVCO Scientific Inc., Asheville, NC). Test Chambers - Fish and test solutions were contained in 5 gallon cylindrical high density polyethylene tanks (Nalge CO., Rochester, NY). Dilution Water Source - Dilution wa ter was obtained in the 3M Environmental laboratory from an on-site well (3M Well #2, St. Paul, MN) . Treatment - Dilution water was carbon-filtered prior to collection using a commercial filtration system (Culligan Water Conditioner, Culligan International CO., Northbrook, IL). Before use, dilution water was aerated for at least 12 hours in order to bring the pH and concentrations of dissolved oxygen and other gases into equilibrium with air. Chax-actex-ization- Carbon-filtered, aerated well water had the following characteristics (MEAN S.D. ): pH, 8. 5 0. 1; dissolved oxygen, 8.5 0.3 mg/L; conductivity, 510 14 p.mhos/cm; alkalinity, 232 8 mg/L as CaCO3, hardness, 272 8 mg/L as CaC03. Test Material General - Commercial PFO (Specialty Chemicals Division, 3M Company, St. Paul, MN, Lot #377) was used for the test. Acute Toxicity - The P. promelas 96 hour LCSO for PFO was determined to be 766 mg/L (3M Environmental Laboratory, unpublished data). Test Concentrations - Fish were exposed to dilution water containing a nominal concentration of 25 mg/L PFO during the uptake phase of the test. An earlier study (3M Environmental Laboratory, unpublished data), indicated that while this concentration did not adversely affect P. promelas, it was great enough to allow for the accurate measurement of PFO in test solutions and fish tissues. Stock Solutions - 1000 mg/L PFO stock solutions were prepared by dissolving solid PFO in dilution water. Test Organism Species - The freshwater fathead minnow, Pimephales promelas, was used as the test organism. Source - Test fish were obtained from an external bioassay supply laboratory (Aquatic Biosystems, Inc., Fort Collins, CO). Care and Handling - Fish were maintained at the 3m Environmental Laboratory in 50 gallon flow-through tanks 2 (Frigid Units, Inc., Toledo, OH) containing carbon-filtered dilution water. Fish were allowed to acclimate to the dilution water for at least 12 days before being used for testing. The concentration of dissolved oxygen in the holding tanks was maintained near 100% saturation by continuous aeration. Fish were fed live brine shrimp and/or TetraMin flake food (TetraWerke, Germany). Water temperature remained relatively constant at approximately 14 C. Age - All fish were 64 days old at the start of the test. Procedure Summaly Qt Test Parameters Test temperature: 20 1 C Photoperiod: 16 h:8 h (light:dark) Test solution volume: 15 L Test solution renewal: none Nominal test concentrations (uptake): 0.0 (Control) and 25 mg/L PFO No. replicates per test concentration: 1 No. organisms per test concentration: 30' Length of uptake phase: 312 h (13 days) Length of depuration phase: 360 h (15 days) Feeding: fish were fed live bring shrimp U,otake/Dei)uration ExQeriment Descz-iption - The uptake/depuration experiment involved exposing P. pz-omelas under static conditions to dilution water to which PFO had been added. The uptake phase was conducted for a period of 312 h (13 days). After 312 h, the fish were transferred to dilution water to which PFO had not been added. This portion of the experiment, the depuration phase, lasted for 360 hours (15 days). Fish and test solution samples were taken at the beginning and end of each phase, and periodically throughout each of the experimental phases. Test Set-Up (Uptake) - Two test tanks were filled with carbon-filtered, aerated dilution water. one tank was dosed with the appropriate volume of 1000 mg/L PFO stock solution to produce 15 L of solution at a nominal concentration of 25 mg/L PFO. The second tank contained only dilution water and served as a control. Dissolved oxygen and pH were measured in the test solutions. A sample of test solution was taken from each tank and stored at 4 C in 6 mL polypropylene scintillation vials (Wheaton Scientific, millville, NJ) until needed for PFO analysis. Thirty P. pz-omelas were added to each of the test tanks. Ten additional fish were sacrificed and their wet weights were 3 determined in order to calculate loading rate. Each of the ten fish was placed in a separate 15 mL polypropylene centrifuge tube (Corning Inc., Corning, NY) and stored at -25 C until analyzed for background PFO concentration. Test Set-Up (Depuration) - Following the uptake phase of the experiment, remaining fish were transferred to two test tanks containing only 15 L carbon-filtered, aerated dilution water. Dissolved oxygen and pH were measured in each tank following transfer of fish, and test solution samples were taken from each tank for PFO analysis. Test Maintenance - Dissolved oxygen measurements in the test tanks were taken daily during both phases of the test. If the dissolved oxygen concentration in either of the test tanks fell below 6.0 mg/L, both tanks were gently aerated for the remainder of the test. Fish were fed live brine shrimp 24, 72, 120, 168, 240, 288, 336, 384, 432, 480, 528 and 576 h after starting the test. Fecal material/excess food was removed from tanks with a disposable glass pipette as needed. Test solution pH was measured once more at the end of each experimental phase. Test Sampling - Five fish were removed from each tank at 192 and 312 h during the uptake phase and again 24, 96, 168 and 360 h after being transferred to clean dilution water. Fish were sacrificed by freezing in liquid nitrogen. Fish were allowed to thaw, and wet weights were determined. Each fish was placed in a separate 15 mL polypropylene centrifuge tube and stored at -25 C until needed for analysis. Test solution samples were taken at each fish sampling time and stored in 6 mL polypropylene scintillation vials at 4 C until needed for analysis. Analysis of PFO whole fish and test solutions were combusted in a modified organic halide analyzer (Dohrmann DX-2000, Rosemount Analytical collection connected MA) . The solutions Inc., Santa Clara, CA), and F- activity in fluid was measured with an ion-selective electrode to an ion analyzer (Orion Research Inc., Boston, concentration of PFO in whole fish tissue and test was calculated from the measured concentrations of F- ion. Data Analysis At each compared 0.05). sampling to that point, the of control weight of PFO-exposed fish fish using a t-test (alpha was One-way analysis of variance and Tukey's HSD test (alpha 0.05) were used to compare the average concentrations of PFO 4 in tissues from PFO-exposed fish during the uptake and depuration experiment. RESULTS: Test organism Loading Rate The loading rate of P. promelas was 124.6 20 mg fish (wet wt.) per liter of test solution. Water Quality Characteristics measured water quality parametersremained within acceptable levels during the static experiment. The average pH of both the control and PFO test solutions was 8.2 0.2 for the entire test. The dissolved oxygen concentration of the control solution dropped below 6.0 mg/L 72 h after starting the test. Therefore, aeration of the test solutions was initiated at 72 h, and continued throughout the remainder of the experiment. with aeration, the dissolved oxygen levels in both test solutions remained at or near 100% saturation. Concentration Of PPO In Test Solutions The concentration of PFO in test solutions remained constant during the static exposure experiment. During the uptake phase, the measured concentration of PFO in spiked dilution water was consistent at approximately 25 mg/L (Table 1). In all other test solutions, during either phase, PFO concentrations were always less than 1.0 mg/L. Sux,vival And Growth Of Test Fish Relative to the control treatment, the survival and growth of P. promelas exposed to PFO were not adversely affected during the experiment. The percent survival of the control fish and the PFO-exposed fish were 97 and 93, respectively. In addition, the average wet weight of PFO-exposed P. px-omelas did not differ significantly from the average wet weight of control fish at any of the sampling points (Table 2, Figure 1). ConcentrationOf PFO in Test Fish Uptake and Depuration The concentration of PFO measured in fish tissue was directly related to the concentration of PFO in test solution. At the beginning of the uptake phase, the PFO concentration in fish tissue was < 1.0 gg/g (wet wt.). After 192 and 312 h of 5 exposure to PFO in dilution water, the average concentration of PFO in fish tissue was 44.7 and 46.7 gg/g (wet wt.), respectively (Table 3, Figure 2). The concentration of PFO in fish did not differ tignficantly between 192 and 312 h of exposure, but was significantly greater at both of these sampling times than at 0 h. 24 h after being transferred to clean water, PFO-exposed fish had an average PFO tissue concentration of 19.9 gg/g (wet wt.). At 96 h post-exposure, the concentration of PFO in PFO-exposed fish had decreased to approximately 8 gg/g (wet wt.), and remained relatively constant until test termination at 360 h (cumulative test time = 672 h). The concentration of PFO in fish tissue at 96, 168 and 360 h post-exposure did not differ significantly from that measured at test start (0 h). Bioconcentration Factor The relationship between exposure to PFO and the amount of PFO in the tissue of P. promelas was described by a bioconcentration factor (BCF). Bioconcentration refers to the increase of a pollutant concentration from water when passing directly into an aquatic species .(Moriarty1983). The BCF was defined as: BCF = C,/C,, where, Ca = equilibrium concentration of a pollutant in the aquatic organism, and C,,= equilibrium concentration of a pollutant in water to which the organism is exposed. Because the concentrations of PFO in test solution and fish tissue did not change between 192 and 312 h, the assumption was made that an apparent equilibrium, or steady state, had been reached in the static exposure system. Therefore, the P. promelas 312 h apparent steady-state BCF (BCF312h) for PFO was calculated as the concentration of PFO in fish tissue at 312 h divided by the concentration of PFO in test-solution at 312 h, or BCF312h = 46.7 gg/g (wet wt.)/25.9 gg/mL = 1.8. REFERENCES: Moriarty, F. 1983. Ecotoxicology: The Study of Pollutants in Ecosystems. Academic Press, Inc., Orlando, FL, 233 p. 233. 6 FIGURE 1. Average wet weights of Control group and PFO-exposed sampled throughout Uptake/Depuration experiment. P. promelas 80 Uptake 70 60 bo 50 40 PFO fish Control fish 30 1 0 100 200 300 400 500 Time (h) FIGURE 2. Uptake and depuration of PFO by P. promelas 60 50 40 rA 3o Uptake 20 0 4-4 io Depuration 0 0 100 200' 300 400 500 Time (h) TABLE 1. Concentration of PFO measured in test solutions. Phase/ Solution Phase Time (h) Avg. PFO Conc . (4q/mL) Std. Dev. UPTAKE Control 0 <1 192 <1 312 <1 - 25 gg/mL (N) 0 25.0 1.8 PFO 192 25.5 2.2 312 25.9 1.8 ------------------------------------------------- DEPURATION Control 0 <1 168 <1 360 0 <1 168 <1 360 Elapsed time (h) from the beginning of each experimental Test solution containing PFO-exposed fish. phase. TABLE 2. Average wet weights of Control group and PFO-Exposed P. promelas. Control Fish PFO-Exp sed Fish Time (h) Average Average Wet Wt. (g) Std. Dev. Wet Wt. (g) Std. Dev. 0 61.7 5.2 61.7 5.2 192 61.4 20.8 57.8 13.4 312 55.3 11.7 51.5 42.0 336 (24)* 49.4 13.9 55.5 22.4 408 (96) 66.4 7.3 65.8 22.4 480 (168) 73.2 44.4 74.6 55.8 672 (360) 1 32.7 t 16.8 1 53.6 1 16.9 1 Number in ( ) indicates elapsed time (h)from beginning of depuration phase. S Results of t-test (a=0.05)comparingwet weights of control and PFO-exposed fish sampled at the same time. I' Not Significant. PS n.s.' n.s. n.s. n.s. n.s. n.s. n.s. TABLE 3. Average concentration of PFO (measuredas F-) in P. promelas tissues. PFO In Fish Comparison Time (h) (Ag/g, Std. Of wet wt.) Dev. Means** 0 1.7 0.4 c 192 44.7 9.1 A 312 46.7 5.8 A 336 (24)* 19.9 5.1 B 408 (96) 7.6 1.3 c 480 (168) 7.6 3.5 c 672 (360) 1 8.0 1.6 c Number in indicates elapsed time (h) from beginning of depuration phase. Means with the same letter are not significantlydifferent at alpha=0.05 by the Tukey-Kramer Honest Significant Difference test. Appendix Comments from Dr. John Giesy,Mchigan StateUniversity March 20, 1995 Dr.Robert Howell 3-M Corp. Environ.Lab.Building2-3E-09 P.O. Box 3331 St.PauL ISW 55113 Dear Robert: I have reviewed the reportentitleAdssessmentof theBioaccumulativePrope?Wes ofAmmonium Perfluorooctmoate:StaftFcuh Test,wtuchpreparedby James Drake. Ifound no fatalerrorsinthe experimentaldesign methods, datainterpretatioornconclusionsdrawn from thisstudy. Ihave =ached a shortreportwbich containmsy specificomments on the studythatwas conducted. and suggestionsforfuturestudies. Pleasecontactme ifyou have additionaqluestions. Sincerely, John P. Giesy,Ph.D. enc: Report Report ong@lfteriment: BioaccumuladveProperdesofAmmo)Mn*erjluoroocianoate.-StatiFcishTes4 whichwas prepitiv@b James Drake. JohnPA, Ph.D. PIL t GiesyEettowilffioIgnyi,@- MarW @W995 Dr.Rollij"lHowell 3.. Environ.L - 2-3E-09 P.0911@@3331 St.Pat 55113 Comments: General.- 1) The setofcqx!iimenwtass welldesigriota=hereareno fataelrrorsinlogice,xperimental designm,ethods selecteds,tatistiacps drawn. 2) The reportiswellwrittenand therest%Lglg&lyp@esented. Muvh 20.1"5 3) 1 agreewiththeconclusionsthatthereislittlbeloaccurnulaticorfiper-fluorooctzlnoa(tFeFC)) by the fatheadminnow. Specific: 1) Tne use oftheFatheadn@amow as a made@,.&p"iesinir@tiaelxpe,-imeitsisappropriate and is usefulindemonst,-atingthatthereislittfO-@'h!bAccumulaptci,o,ntentioaf@P'FO, I-lowever,this experiment does not address the issLic-of@,@@-dumulat'i@o-nifaood, by tflispec:-Ieosr larger predatoryfishes,Some considerationst6Od.14 made of fa-,,@eadcsonta:-ninatedwith PFO to largerfishesin a longerexpoqitm-@ 2) ne exposureperiodseems tobe adeqLatt*-4itabEshthatthe5sh had attaineda steady state cor.centratio(rS,S.C) from exte.-nael>@@ However, ;r.:@ut,,ierxeperiment!;itwould be usefulto conduct the exposure atlea@t_=%,$amplingperiod(4-5 days)longei-to establish more defu@tivelythat SSC had been a@@ 3) The resultosfthestudyindicattehatthe,Wpa -=mulation.fact,,iJsrapproximatel,1.8.While thisvalueindicatetshatthereislittldet.ct.,@amtionofPFO, tietr-aebloaccumulationfactor isprobablyevenless.I thinkthatmosti@f'Ai&-WO thatwas accumulated by the fishwas due to surfacesorptior,7,,.,iust,he studypr6bibl)t'@>-'ve,a-teesttihmetrueBCF. Baseclon the data presented,the trueBCF isprobably&.fCX42@,ofeight(8) or nire(9)lessthan the reported value,I would suggestthat'inany futur#,@ thatthefishbe -"nsedforapproximatelyfour hour-sin cleanflowingwater before theyA- the cleanwater to follov.d,epuration- While the accumulationpotential (V'la*Llsvmeall, i-el@at@tlovlo-ther halogenated hydrocarbons,itisnot unexpected, bas6c-'o he structureoi@-*@choempound, a-risdimilarto theBCF expected fordetergents. The curtentstudyaddressedonlv a siKgejw,c."posL,,croencenlation.The factthattherewas accumulationof PFO intothe fishesv#uqti.ymsnot rapidlydt@puratedindicatesthatthereis accumulationintoa tightlybound pool@'@' thatthe concentratioonf PFO inthatpool didnot se--mto ircreasedur;ng t,@,z that t@l'pscol had become saturated. Ifso,thisindicatesthatbased on a pharz!Y@o-tctpetaiscsessmeni:thatthe BCF COL@ldbe biased by the use of a single,relativelygreat'@&IN-@ggeconcentratioii-The existenceof the tightly bound pool suggeststhattherearetwo@.,dem"'mtiocnomponeit.s,one very rapid and a second from which thereseems to be no depurabiDwU allduringthe @,.,",raotf',tIhoenstudy. Ifthisis so,thenexposureto lesserconcentratica-".f@F-FOforlonger-@)e-iodosf time wc,uld possible resulitnthesame rna"=Um bound PF0. l@tm,theBCF, isthe ratioof PFO inthe fish to thatin the water would be greate@-Zhus, the questionis,are the pharrnaco-kinetic constantstrueconstants,which are imiiq*Atrentof exposurc:concentration.This was not consideredinthepresentstudy.For'Ln5td, rwwiEtheBsh were e:,:posetdo a concentrationone hundredthasgreatfor a longer pen'od:,6f but stilrleac'tl-@,h-e,sdame totalbody burden, CricryECoto)dcologyL,-X- -i'@&r1c.h0,1995 2 theBCF forPFO accumulationby the fatheadrftinnowswould be one hundred (100)times as great.Future studiesshould includean assessmentof the pharmaco -kineticonstants dependance on durationand intensitoyf exposure. 4) The durationof thedepurationphase was adequateto estabhshthatthe fishhad reached a concentratio(n5mg@k& ww) thatseemed tobe tightlbyound inc)ron the fishand thatfurther depurationwas unlikely.The accumW46,GWf asmuch as 5 ppm isnot a smallamount of compound, ifthe exposure concentral-w-n-s-a,t,Aaellrelevantfor expected en-,,,ironmental concentrationsT.his resultraises+.htt"tienfonf where the PFO is associatedAith the organism. Isitairfar-e-boundor bouncl.,@yA temal tissuesof t@e fish? If so, which tissues are the targetsfor aci@-,imulation? 5) WUe the experiment was not conducV4W-t,o7,*sesstoxicitoyf IIFO,the resultsindicatethat PFO isnot acutelytoxicto fatheadrtm4p" Thisissimilar1,oresultswith PFO inother studiesand consistentwith the media4;pjgF,4bcleimitLC-50 ofover 700 mg/L. The mechanism of actionof perflb&.gO. '@d compounds, ivhich is often peroxisome proliferatioins,a more chroniceffect@n&,anladverseeffectsdue thismechanism of action would not be expectedin a short-ternrsM-i#T.hus, the chronictoxicitvof PFO to fisl-4 especiay predatoryfishc@rde,maim an bini@s@orl Potentialefi'ectosn long-term survival, growth and reproduct-iowne,-enot @3:cwfmorMin the bioaccumulationstudy with fa.thead n@=ows. 7) The use of a staticsvstem seems justiheo4kh@gactualconcentratici-wiesre measured and there was no degradationof PFO and a conzaa-'nt-oexspure concentraton was maintained. Future studieswith smallerconcentrationsshnM@tbTaider theuse of a flow-through systen-wLh,ich isthe preferredmethodolozv indefiniwve iesofbioaccumulation. Pot,?ntialfutursetudies: 1) Dispositioonf PFO infishtissues.I vjWdWu-Uest a radio-tracesrtudyfollowedby wholeorganism autoridiogr-.phy. 2) The factthatthereseems to be irrevem therecould be considerableaccumula6' cur,rentstudy only addressed blo4 biomagnificatiosntudyisindicated. dingof PFO intothe fatheads,indicatetshat eciallfyrom thedi-tof predatoryfishes.The ation from wate,,, A dietarystudy or 3 Chronic effe= ofexposuretoPFO on iiEp;,c4iktioofnfatheadrt@nnows. This isa relatively straigh-tforward studyto conduct an@f<,*_Oucj6dveneeded infon-natioonn the potentialfor ch.roniceffectson sur@ival,gro,,A,-atnh.d.i.elwmiiy. Ciesy@',aoW)dcoloIgryv.- 19,95 3 4) The potentialforlong-tenn,chroniceffectswas not addressedinthisstudyor any others. The potentiaflorlong-teribniomagnificatioannd effectscould be assessedina longer-term feedingstudywith predatoryfishes. March 20. 1995 4