ACUTE TOXICITY OF THREE FIRE-RETARDANT AND TWO FIRE-SUPPRESSANT FOAM FORMULATIONS TO THE EARLY LIFE STAGES OF RAINBOW TROUT (ONCORHYNCHUS MYKISS)

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1 Environmentl Toxiology nd Chemistry, Vol. 15, No. 8, pp , 1996 Printed in the USA /96 $ ACUTE TOXICITY OF THREE FIRE-RETARDANT AND TWO FIRE-SUPPRESSANT FOAM FORMULATIONS TO THE EARLY LIFE STAGES OF RAINBOW TROUT (ONCORHYNCHUS MYKISS) MARK P. GAIKOWSKI, STEVEN J. HAMILTON,* KEVIN J. BUHL, SUSAN F. MCDOLD nd CLIFF H. SUMMERS Ntionl Biologil Servie, Midwest Siene Center, Ynkton Field Reserh Sttion, Ynkton, South Dkot 57078, USA Deprtment of Biology, University of South Dkot, Vermillion, South Dkot 57069, USA (Reeived 25 My 1995; Aepted24 Jnury 1996) AstrtLortory studies were onduted with five erly life stges of rinow trout, Onorhynhus mykiss, to determine the ute toxiities of five fire-fighting hemil formultions in stndrdized soft nd hrd wter. Eyed egg, emryo lrve, swim-up fry, nd 60- nd 90-d posthth juveniles were exposed to three fire retrdnts ( LCG-R, GTS-R, nd Phos-Chek D75-F) nd two fire-suppressnt foms (Phos-Chek WD-881 nd Silv-Ex). Swim-up fry were generlly the most sensitive life stge, wheres the eyed-egg ws the lest sensitive. Toxiity of fire-fighting formultions ws greter in hrd wter thn in soft wter for ll life stges tested with GTS-R nd Silv-Ex nd for 90-d-old juveniles tested with LCG-R. The fire-suppressnt foms were more toxi thn the fire retrdnts. The 96-h medin lethl onentrtions (LC50s) were rnked from the most toxi to the lest toxi formultion s follows (rnges re the lowest nd highest 96-h LC50 lulted for eh formultion): Phos-Chek WD-881 (11 44 mg/l), Silv-Ex (11 78 mg/l), Phos-Chek D75-F (218 3,600 mg/l), GTS-R (207 6,000 mg/l), nd LCG-R (872 10,000 mg/l). Toxiity vlues suggest tht identl entry of fire-fighting hemils into quti environments ould dversely ffet fish popultions. KeywordsFire retrdnts Fire suppressnts Toxiity Rinow trout INTRODUCTION Fire-fighting hemil formultions re used widely throughout North Ameri nd re essentil tools for the ontrol nd mngement of wildlnd fires. These hemil formultions were pplied y irrft in nerly 15,000 fire-retrdnt drop missions delivering out 64 million L in 1971 [1]. Approximtely 91 million L of mmoni-sed fire-retrdnt mixtures were pplied in the United Sttes in 1992 (C. Johnson, personl ommunition) to lnds often djent to quti hitts, therey reting the possiility of inidentl fish kills. Although most fire-retrdnt formultions re elieved to hve miniml toxiity to quti ognisms, fish kills hve een ssoited with identl strem ontmintion during fire-retrdnt drops [2]. Almost omplete mortlity of trout ws reported in setion of the Little Firehole River due to fire-retrdnt drop during the mjor 1988 fire in Yellowstone Ntionl Prk [3]. There is puity of informtion out the toxiity to fish of fire-fighting hemils urrently in use. Although studies hve een onduted using onstituent hemils of fire-ontrol hemils [4 7], reltively few studies hve een onduted to determine the ute toxiity of firefighting hemil formultions to freshwter fish [8 10]. In ddition, most of these studies were onduted with formultions tht re no longer in use. Toxiity testing hs een onduted y the mnufturers or ontrt lortories; however, severl of these tests were not onduted in stndrdized wters. Moreover, experiments onduted y the mnufturers utilized only one life stge of fish nd one type of wter; thus, dt re lking * To whom orrespondene my e ddressed. Referenes to trde nmes, ommeril produts, or mnufturers do not imply or onstitute government endorsement or reommendtion for use. on oth the sensitivity of vrious life stges of fish nd the influene of different wter qulities on the toxiity of these hemil formultions [11 17]. Two generl tegories of hemils re typilly utilized in fire fighting. The first tegory is fire-suppressnt foms, shortterm wetting gents tht enhne the ility of wter to penetrte fuel soures, thus reduing the ility of the fuel to ignite. These formultions lso t y slowing the evportion of wter, inresing wter retention on fuel soures, nd reduing ir ontt with the fuel y insulting the fuel soure from the het of the fire. However, fire-suppressnt foms do not redue omustion fter wter hs evported from the fuel soure. Applition onentrtions of fire-suppressnt foms rnge from 0.1 to 1.0% onentrte in solution [18,19]. Fire-suppressnt foms re generlly omposed of mixture of surftnts, fom stilizers, inhiiting gents, nd solvents [18,19]. The use of fire-suppressnt foms in fire fighting is eoming more prevlent euse the mount of wter required n e redued y 60% [20]. The seond tegory is fire-retrdnt formultions, whih hve the ility to form long-term omustion rrier fter the evportion of the wter. In generl, the retrdnt hemils re omposed of mmonium slts with thikening gent, suh s mmonium sulfte or mmonium polyphosphte with n ttpulgite ly thikener or dimmonium phosphte with gurgum-derivtive thikener. Formultion effetiveness depends on the mount of slt pplied per unit surfe re. Fire-retrdnt effetiveness is inresed y utilizing highly onentrted solutions ( g/l), whih re very orrosive due to their high slt ontent. Fire-retrdnt formultions ontin rust inhiitors suh s sodium dihromte s well s tre mounts of olornts, suh s ferri oxide, to mrk drop sites. The ute toxiity of five fire-ontrol hemils to the erly life stges of rinow trout (Onorhynhus mykiss) ws ssessed 1365

2 1366 Environ. Toxiol. Chem. 15, 1996 M.P. Gikowski et l. Tle 1. Life stges of rinow trout tested with five fire-fighting hemil formultions in ASTM soft nd hrd reonstituted wter Life stge Lot Eyed egg 2 Emryo lrve S fry Swim-up fry dph 1 1 Wter type Age Weight (g) 90 dph d ( ) d ( ) 0.10 f ( ) 0.10 f ( ) 0.09 f ( ) 0.09 f ( ) 0.62 g ( ) 0.41 g ( ) 1.50 h ( ) 1.19 h ( ) Totl length (mm) ml e d 5.66 mm ml e d 5.66 mm 21 f (19 22) 21 f (19 22) 25 f (23 26) 25 f (23 26) 44 g (34 52) 39 g (33 45) 56 h (47 64) 53 h (49 60) ASTM Amerin Soiety for Testing nd Mterils. Dys post medin hth dy (dph) to test initition. Mesurements re men vlues (with rnge in prentheses) of ontrol fish. d Averge of two pools of 10 eggs eh. e Volume displement; d dimeter. f N 20 (pool of hrd nd soft ontrol tretments). g N 20. h N 30. using stti 96-h toxiity tests. The hemils tested were seleted euse they re the most ommon hemils used to fight forest nd rngelnd fires nd re urrently pplied to wide vriety of hitts. Studies were onduted with three fire retrdnts, GTS-R, LCG-R, nd Phos-Chek D75-F, nd two fire-suppressnt foms, Phos-Chek WD-881 nd Silv-Ex. Cold-wter speies suh s rinow trout re often ssoited with forested res in the western United Sttes, where lrge mounts of fire-ontrol hemils re used to omt rngelnd nd forest fires. Inurte or delierte drops of fire-fighting formultions ner strems nd rivers my dmge those quti eosystems. Rinow trout were used in tests euse they represent top-level onsumer in old-wter eosystems. MATERIALS AND METHODS Culture This study ws onduted t the Ynkton Field Reserh Sttion (YFRS) of the Midwest Siene Center, Columi, Missouri, USA. Tle 1 lists for eh life stge of rinow trout (Onorhynhus mykiss) the ge t test initition, lot numer, men weight, nd men totl length. Fish were ultured t YFRS in erted well wter (hrdness 290 1,100 mg/l s CCO 3, lklinity mg/l s CCO 3, ph ). Two lots of rinow trout were otined from Ennis Ntionl Fish Hthery, Ennis, Montn, USA, s eyed eggs. Both lots of rinow trout were of the sme strin (MConughy) to minimize potentil vrition in sensitivity [21]. The life stges tested re defined s follows: eyed eggs with distint eye spots, emryo lrve (tests were initited with eyed Tle 2. Wter qulity hrteristis (men with SD in prentheses) of the wter used in ute toxiity tests with five life stges of rinow trout exposed to five fire-fighting hemil formultions in ASTM soft nd hrd wter Chrteristi (N 7) Wter type (N 7) ph 7.5 (0.09) 8.2 (0.09) Condutivity (mho/m t 25C) 164 (4.07) 542 (8.12) ness (mg/l s CCO 3 ) 42 (0.79) 163 (1.80) Alklinity (mg/l s CCO 3 ) 33 (0.75) 112 (2.00) Clium (mg/l) 8 (0.42) 28 (0.90) Mgnesium (mg/l) 5 (0.48) 23 (0.95) Chloride (mg/l) Sulfte (mg/l) 0.5 (0.42) 40 (0.41) ASTM Amerin Soiety for Testing nd Mterils. 2.8 (0.59) 160 (19.73) eggs tht hthed during testing), s fry (levins possessing definite yolk s), swim-up fry (fry hd sored most of their yolk s nd were tively swimming in serh of food), nd juveniles 60 nd 90 d posthth (dph) (the 90-dph fish looked like smll dults with prr mrks). S fry were exposed to Fire- Trol LCG-R to retest the exposure of emryo lrve to the retrdnt, whih did not produe n eptle medin lethl onentrtion (LC50) in the first test. Dilution wter nd test hemils Stti ute toxiity tests were onduted in stndrdized reonstituted hrd nd soft wter [22]. Dilution wter ws prepred y dding pproprite mounts of regent grde slts (CSO 4 2H 2 O, MgSO 4, NHCO 3, nd KCl) to known mounts of purified wter. Purified wter ws prepred y pssing well wter through wter softener, reverse-osmosis unit, nd deionizer. After mixing nd ertion of the slts in the purified wter, hemil hrteristis of the dilution wter were determined ording to stndrd methods [23,24] (see Tle 2). Chemil formultions used s test hemils were reeived from the U.S. Forest Servie, Intermountin Fire Sienes Lortory, Missoul, Montn, on Novemer 20, All test onentrtions nd susequent LC50s were sed on 100% tive formultion euse the proportionl ompositionl nlyses re not ville for puli dislosure. The following five hemil formultions were tested. Fire- Trol GTS-R (FT GTS-R; lot numer 84FT232) is long-term, dry fire-retrdnt formultion mnuftured y Chemonis Industries, Phoenix, AZ, USA. It is omposed of mmonium sulphte, dimmonium phosphte, gur gum thikener, spoilge inhiitor, orrosion inhiitor, nd iron oxide s oloring gent [16]. LCG-R (FT LCG-R; lot numer 91FT11) is longterm, liquid fire-retrdnt formultion lso mnuftured y Chemonis Industries. It is omposed of mmonium polyphosphte, ttpulgite ly thikener, orrosion inhiitor, nd iron oxide s oloring gent [17]. Phos-Chek D75-F (PC D75-F; lot numer A) is long-term, dry fire-retrdnt formultion mnuftured y Monsnto, Ontrio, CA, USA. It is omposed of mmonium sulfte, mmonium phosphte, gur gum thikener, ornge oloring gent, nd other dditives [25]. Phos-Chek WD-881 (PC WD-881; lot numer A,

3 Fire-retrdnt toxiity to rinow trout Environ. Toxiol. Chem. 15, th 18227) is liquid, fire-suppressnt fom formultion produed y Monsnto. Its formultion onsists of mixture of nioni surftnts, fom stilizers, nd solvents (hexylene glyol) [18]. Silv-Ex (lot numer 75451, th US6203) is liquid firesuppressnt fom formultion mnuftured y Ansul Fire Protetion, Mrinette, WI, USA. Silv-Ex ontins nioni surftnts, stilizers, inhiitors, nd solvents (diethylene glyol monoutylether) [19]. Test methodology Rinow trout eyed eggs, emryo lrve, nd s fry were limted to the test wter nd temperture over 48-h period prior to testing. All other life stges were limted over 96-h period. Fish were not fed during limtion. Stti ute toxiity tests followed the guidelines outlined y the Amerin Soiety for Testing nd Mterils (ASTM) [22]. Eh test onsisted of exposing groups of 10 fish to series of seven or eight toxint onentrtions. There ws 60% dilution ftor etween eh toxint onentrtion. One ontrol exposure ws used in eh set of life-stge tests nd for eh wter qulity tested. Temperture ws mintined t 12 1C y immersion of test vessels into temperture-ontrolled wter ths. Test solutions were prepred y diretly dding pproprite mounts of FT LCG-R, FT GTS-R, or PC D75-F to the test vessel. GTS-R nd PC D75-F were mixed two to three times for 40 to 50 s with three-lde, polyethylene stirrer tthed to n eletri drill t 1,000 to 1,200 rpm. This mixing ws usully suffiient to ring the test formultion into solution for short time, ut fter 24 h of exposure some test mteril, proly thikener nd some olornt, hd preipitted. Fire- Trol LCG-R ws prepred in similr fshion ut ws mixed only one for 40 to 50 s per test vessel. Phos-Chek WD-881 nd Silv-Ex were dded y prepring stok solutions in deionized wter nd then using pipette to ple n pproprite liquot in eh test vessel. Both PC WD-881 nd Silv-Ex were hnd-mixed with Teflon or glss stir rods to prevent exessive foming. Eyed eggs, emryo lrve, s fry, nd swim-up fry were tested in 3.9-L glss test vessels ontining 3.0 L of dilution wter. During testing with eyed eggs nd s fry, test orgnisms were onfined in 0.47-L glss jrs with the ottom removed nd repled with stinless-steel sreen fixed in ple with silione. The hthing ups were suspended y ltex tuing from glss rods in the test vessels so tht eyed eggs or s fry were in the test solution ut the up rim ws ove the wterline. Tests onduted with 60-dph juveniles were onduted in 19.6-L glss test vessels ontining 15 L of dilution wter. The 90-dph juveniles were tested using two replite 19.6-L test vessels ontining 15 L of dilution wter nd five fish eh. Replite vessels were used in the 90-dph juveniles to mintin loding densities of less thn 0.8 g/l [22]. Eyed eggs, s fry, nd swim-up fry were rndomly trnsferred from the limtion hmer to plsti weigh ots filled with dilution wter y glss pipette to minimize hndling stress. Exess wter ws dented from the weigh ots, nd the test orgnisms were distriuted to rndomized test vessels. Juveniles were rndomly distriuted two t time to test vessels using smll dip net. Mortlity nd norml ehvior were monitored nd reorded t 24-h intervls during tests, nd ded fish were removed t those intervls. Whitening of eyed eggs ws the riterion for mortlity in these tests. Emryo lrve nd s fry were exmined with 30 disseting mirosope for the presene of hertet, the sene of whih ws the riterion for mortlity. Cesstion of operulr movement ws the riterion for mortlity in tests with swim-up fry nd 60- nd 90-dph juveniles. At the onlusion of eh test, ll ontrol eggs or fish were weighed nd totl length ws mesured, exept in the emryo lrve tests, in whih ontrol levins were disrded prior to mesurement. Weight nd totl length of eh life stge tested re summrized in Tle 1. Dissolved oxygen nd ph were mesured nd reorded in the ontrol, low, medium, nd high test onentrtions, with live fish present t 0, 48, nd 96 h of exposure. Dissolved oxygen ws mintined t greter thn 40% sturtion, s reommended y the ASTM [22], in ll ut one test. Rinow trout 60-dph juveniles exposed to FT LCG-R in soft wter hd dissolved oxygen of 31.1% sturtion t 96 h, proly euse seven fish hd died in this onentrtion during the preeding 24 h. The live fish in this test showed no overt signs of oxygen deprivtion. Eight tests hd dissolved oxygen redings elow 60% sturtion t 48 h (rnge, %), ut none of the fish in these tests showed overt signs of oxygen stress. Temperture ws mesured dily in the wter th. Ammoni ws mesured in 100-ml smples of the ontrol, low, medium, nd high test onentrtions ontining live fish t 0, 48, nd 96 h of exposure. Conentrtions were determined with n Orion mmoni-seletive eletrode tthed to Fisher Aumet model 610 ph meter reding reltive millivolts. A regression eqution ws determined for eh set of tests to llow predition of mmoni s nitrogen (NH 3 -N) t the 96-h LC50; regression equtions re given in Gikowski [26]. Equtions were determined y regressing the NH 3 -N estimtes for the low, medium, nd high test onentrtion using initil (0-h) NH 3 -N estimtes ginst the pproprite test onentrtions of the hemil eing tested. The 0-h NH 3 -N estimtes were used for dt nlysis to minimize the influene of mmoni ontriution from test fish or voltiztion of mmoni ontriuted y the formultion. Un-ionized mmoni onentrtions were lulted y determining the NH 3 -N onentrtion from the regression eqution oeffiients nd the 96-h LC50 onentrtion. The perentge of un-ionized mmoni ws estimted y using the high nd low ph reorded t test initition. The two perentge vlues were then used to determine the NH 3 rnge. Nitrte nd nitrite onentrtions were determined olorimetrilly using dmium redution proedure nd stndrd dditions method [27]. Eh smple ws nlyzed in duplite. Stndrd dditions to nitrte nd nitrite smples were 0.2, 0.4, nd 0.6 ml nitrte nitrogen stndrd solution (100 mg/l s NO 3 -N) nd 0.4, 0.6, nd 0.8 ml nitrite nitrogen stndrd so- lution (100 mg/l s NO 2 -N). Eh stndrd ddition ws nlyzed in duplite. Anlysis ws onduted on onentrtions of three fire-retrdnt hemils, FT GTS-R, FT LCG-R, nd PC D75-F; fom suppressnts were not tested. Chemil ws dded to test vessels mthing those used in tul tests ut without fish. Fire-retrdnt solutions were prepred to simulte exposure t the 96-h LC50s of the swim-up fry life stge, exept PC D75-F in soft wter, whih replited the LC50 of the 90-dph life stge juveniles. A regression eqution ws determined for tests onduted with rinow trout nd hinook slmon (Onorhynhus tshwytsh) tested t 12C (n 4). The regression eqution ws used to lulte the nitrte nd nitrite onentrtions t the 96-h LC50 for the eyed egg, emryo lrve, nd 60- nd 90-dph

4 1368 Environ. Toxiol. Chem. 15, 1996 M.P. Gikowski et l. Tle 3. Aute toxiity (96-h medin lethl onentrtion [LC50] with 95% onfidene intervl in prentheses) of five fire-fighting hemil formultions to five life stges of rinow trout exposed in ASTM soft nd hrd wter Chemil Wter type 96-h LC50 Egg Emryo lrve Swim-up fry 60 dph 90 dph GTS-R LCG-R 3,600 A 6,000 A 10,000 A 718 B ( ) 606 B ( ) 3,600 e B 10,000 A 2,642 e B (2,117 3,249) Phos-Chek 1,700 A 266 e B D75-F ( ) 3,600 A 235 e B ( ) Phos-Chek 44 f A 13 B WD-881 (10 17) 22 A 10 B (18 27) (8 13) Silv-Ex 78 A 15 B* (12 20) 47 A 11 B* (38 62) (9 14) 363 C* ( ) 207 d C* ( ) 910 C (722 1,115) 872 C (685 1,066) 279 B ( ) 218 B ( ) 13 B (10 17) 11 B (9 14) 20 BC* (16 25) 13 B (10 17) 390 C* ( ) 234 C* ( ) 1,080 CD (880 1,353) 1,413 D (1,105 1,724) 234 B ( ) 218 B ( ) 15 B (12 19) 13 B (10 17) 22 C* (17 28) 14 B* (11 18) 363 C* ( ) 234 C* ( ) 1,413 D* (1,105 1,724) 1,006 C* (780 1,300) 218 B ( ) 218 B ( ) 20 C (16 25) 13 B (10 17) 22 C* (17 28) 15 B* (12 19) ASTM Amerin Soiety for Testing nd Mterils. Asterisks denote signifint differene (p 0.05) in toxiity of test formultions etween soft nd hrd wter. Common upperse letters denote no signifint differene (p 0.05) mong life stges within test formultion nd wter qulity. dph Dys posthth. No prtil kills; 95% onfidene intervl: lower limit highest test onentrtion with 0% mortlity, upper limit lowest test onentrtion with 100% mortlity. d LC50 lulted using inomil test. e Tests were strted with true s-fry. f LC50 lulted y inomil test; less thn 70% mortlity in highest test onentrtion. life stges. A regression eqution ould not e derived for PC D75-F. Sttistil nlysis Most 96-h LC50 vlues nd 95% onfidene intervls were lulted using the moving-verge ngle method [28]. In tests with less thn two onentrtions ove the LC50, the inomil distriution method [28] ws used. In tests with no prtil mortlity, the upper 95% onfidene limit ws ssumed to e the lowest test onentrtion with 100% mortlity nd the lower 95% onfidene limit ws ssumed to e the highest test onentrtion with 0% mortlity. All LC50 vlues re expressed s nominl onentrtions of the fire-ontrol formultion. Formultions were rnked ording to toxiity y the Friedmn test [29]. The stndrd error of the differene s desried y Sprgue nd Fogels [30] nd Zr [31] ws used to determine sttistil differenes etween LC50 vlues. Vlues were onsidered to e signifintly different t p Comprisons nd rnkings of tests in whih n LC50 vlue ould not e determined due to insuffiient mortlity were omplished y ssuming the highest onentrtion tested in tht series ws less thn the LC50. These LC50 vlues re therefore reported s greter thn the highest onentrtion tested. RESULTS The 96-h LC50 vlues determined for the five life stges tested with the five formultions in two wter types re presented in Tle 3. No mortlity ws oserved t ny life stge in six ontrol exposures in hrd wter nd six ontrol exposures in soft wter. The emryo lrve 96-h LC50 for FT LCG-R ws determined with s fry. The LC50 vlues for the five life stges tested t eh 24-h oservtion period were reported y Gikowski [26]. Most mortlity ourred within the initil 24 h of exposure, with little hnge in LC50 vlues over the reminder of the test [26]. The two fire-suppressnt foms, Phos-Chek WD-881 nd Silv-Ex, were more toxi thn the fire retrdnts tested (Tle 3). Both hd LC50 vlues tht were t lest 10 times lower thn the LC50 for the next two most toxi formultions, PC D75-F nd FT GTS-R, nd pprox. 67 times lower thn the LC50 for FT LCG-R. For ll life stges, the rnk order of the fire hemils tested for oth soft nd hrd wter tests, sed on the Friedmn test, from most toxi to lest toxi ws PC WD-881, Silv-Ex, PC D75-F, FT GTS-R, nd FT LCG-R (ll were signifintly different, p 0.05). Both fire-suppressnt foms hd very similr 96-h LC50s, rnging from 10 to 44 mg/l for PC WD-881 nd from 11 to 78 mg/l for Silv-Ex (Tle 3). Phos-Chek D75-F nd FT GTS-R hd similr rnges, 218 to 3,600 mg/l for PC D75-F nd 207 to 6,000 mg/l for FT GTS-R (Tle 3). Phos-Chek D75-F nd FT GTS-R were 19 to 77 times less toxi thn PC WD-881 nd Silv-Ex. LCG-R ws the lest toxi formultion tested, with 96-h LC50s rnging from 872 to 10,000 mg/l (Tle 3). Life stge nd wter type Life stge nd wter type plyed importnt roles in determining the reltive sensitivity of rinow trout to the five formultions. For ll test hemils, the rnk order of the life stges

5 Fire-retrdnt toxiity to rinow trout Environ. Toxiol. Chem. 15, Tle 4. Rnge of estimted un-ionized mmoni onentrtions (mg/l) t the 96-h medin lethl onentrtion (LC50) for the five rinow trout life stges tested with five fire-fighting hemil formultions in ASTM soft nd hrd wter Life stge Formultion Wter type Eyed egg Emryo lrve Swim-up fry 60 dph 90 dph Fire Trol GTS-R LCG-R Phos-Chek D75-F Phos-Chek WD-881 Silv-Ex ASTM Amerin Soiety for Testing nd Mterils. dph Dys posthth. Conentrtion given s mg/l NH 3 -N. tested, sed on the Friedmn test, from most sensitive to lest sensitive ws s follows: Swimup fry 90-dph juveniles 60-dph juveniles emryo lrve eyed egg (ommon underline, not signifintly different; p 0.05). Most mortlity ourred within the initil 24 h of exposure for most life stges. The emryo lrve life stge ws n exeption in tht LC50 vlues deresed t hthing, suggesting tht the lrvl stge ws more sensitive thn the egg stge. Bsed on the 96-h LC50s, eyed eggs were etween 1.3 nd 25.6 times less sensitive to toxints thn other life stges. The 96-h LC50s for swim-up fry were 2 to 30 times less thn the 96-h LC50s of eyed eggs. The eyed-egg stge, regrdless of wter type, ws the lest sensitive life stge, with the highest 96-h LC50 vlues (Tle 3). The 96-h LC50 determined for swim-up fry (910 mg/l) tested with FT LCG-R in soft wter ws not signifintly less thn tht for the 60-dph juveniles (1,080 mg/l) ut ws signifintly lower thn the vlues determined for the other life stges tested. In hrd wter tests with FT LCG-R, swim-up fry hd 96-h LC50 (872 mg/l) tht ws not signifintly less thn the 96-h LC50 determined for 90-dph fish (1,006 mg/l). Swim-up fry nd 90-dph juveniles were signifintly more sensitive thn the other life stges tested with FT LCG-R in hrd wter. nd hrd wter results for FT GTS-R were similr euse for oth wter qulities, the swim-up fry nd the 60- nd 90-dph juveniles were not signifintly different in their sensitivity ut were signifintly more sensitive thn the emryo lrve (Tle 3). The ltter ws signifintly more sensitive thn the eyed eggs. The emryo lrve, swim-up fry, nd 60- nd 90-dph life stges tested with PC D75-F in soft wter were not signifintly different from eh other, ut ll were signifintly more sensitive thn the eyed-egg life stge (Tle 3). This pttern ws the sme in tests with hrd wter nd PC D75-F. Emryo lrve, swim-up fry, nd 60-dph juveniles tested with PC WD-881 were signifintly more sensitive thn 90-dph juveniles tested in soft wter. The eyed-egg life stge tested with PC WD-881 in soft wter ws signifintly less sensitive thn ll other life stges tested. No signifint differenes existed etween the emryo lrve, swim-up fry, nd 60- nd 90-dph juvenile life stges tested in hrd wter (Tle 3). Emryo lrve tested with Silv-Ex in soft wter were not signifintly more sensitive thn the swim-up fry life stge ut were signifintly more sensitive thn the other life stges tested. The 96-h LC50s determined for the swim-up fry nd 60- nd 90-dph juveniles were not signifintly different. The eyedegg life stge tested in soft wter ws signifintly less sensitive thn ll other life stges. Tests onduted with Silv-Ex in hrd wter resulted in no signifint differenes etween the 96-h LC50s for emryo lrve, swim-up fry, or 60- nd 90-dph juvenile stges. Rinow trout eyed eggs tested with Silv-Ex in hrd wter were signifintly more resilient thn the other life stges. Wter type ffeted the toxiity of three fire-ontrol hemils. The formultions FT GTS-R nd Silv-Ex were generlly more toxi in hrd wter thn in soft wter (Tle 3). Swim-up fry nd 60- nd 90-dph juveniles were signifintly more sensitive to FT GTS-R in hrd wter thn in soft wter (Tle 3). For tests onduted with Silv-Ex, the eyed egg ws the only life stge not signifintly more sensitive when tested in hrd wter s ompred to soft wter, proly euse insuffiient mortlity t the high onentrtion ourred nd preluded determintion of 96-h LC50. Wter qulity did not influene toxiity in tests with PC D75-F, PC WD-881, or FT LCG-R exept with 90-dph fish (Tle 3). Ammoni, nitrte, nd nitrite Estimted un-ionized mmoni onentrtions t the 96-h LC50 for the five fire-ontrol hemils re given in Tle 4. Comprison of the regression equtions for eh wter type nd formultion indited tht oth FT GTS-R nd PC D75-F hd similr slopes [26]. The slopes indited the mmoni perentge of the formultion, i.e., tht pprox. 20 to 23% of oth FT GTS-R nd PC D75-F ws mmoni, wheres FT LCG-R ws only 10 to 12% mmoni. Un-ionized mmoni rnges t the 96-h LC50 were similr for the three fire retrdnts (FT GTS-R, mg/l; FT LCG-R, mg/l; nd PC D75-F, mg/l), exluding NH 3 estimtes for the eyed-egg tests. GTS-R hd higher ph rnge thn FT LCG-R nd PC D75-F in ll ut two ses, whih ontriuted to its greter mount of un-ionized mmoni. In these two ses, emryo lrve exposures to PC D75-F in hrd nd soft wter hd higher ph thn those in FT GTS-R. Due to extremely low onentrtions of NH 3 -N

6 1370 Environ. Toxiol. Chem. 15, 1996 M.P. Gikowski et l. Tle 5. Rnge of estimted nitrte (mg/l NO3 -N) nd nitrite (mg/l NO2 -N) onentrtions t the 96-h medin lethl onentrtion (LC50) for the five life stges of rinow trout tested with five fire-fighting hemil formultions in ASTM soft nd hrd wter Formultion GTS-R LCG-R Phos-Chek D75-F GTS-R LCG-R Phos-Chek D75-F Wter type Eyed egg Emryo lrve Nitrte Nitrite Life stge Swimup fry dph dph ASTM Amerin Soiety for Testing nd Mterils. Mesured vlue. dph Dys posthth in PC WD-881 nd Silv-Ex, further nlysis of NH 3 onentrtions t the 96-h LC50 ws not ompleted. Estimted nitrte nitrogen ( NO 3 -N) nd nitrite nitrogen ( NO 2 -N) onentrtions t the 96-h LC50 for four life stges, nd mesured for the swim-up fry stge, re given in Tle 5. LCG-R hd sustntilly more nitrte nd nitrite thn either FT LCG-R or PC D75-F. Nitrite onentrtions were 21- to 26-fold higher thn nitrte in FT GTS-R, wheres they were 10- to 19-fold higher thn nitrte in FT LCG-R. In ontrst, nitrite onentrtions were three- to fivefold lower thn nitrte in PC D75-F. Nitrte nitrogen onentrtions rnged from 0.17 to 5.4 mg/l in FT GTS-R nd from 2.0 to 60 mg/l in FT LCG-R. Mesured onentrtions of nitrte nitrogen in PC D75-F were etween those in FT GTS-R nd FT LCG-R. Estimted nitrite nitrogen onentrtions t the LC50 rnged from 3.6 to 113 mg/l in FT GTS-R nd from 38 to 540 mg/l in FT LCG-R. Mesured onentrtions of nitrite nitrogen in PC D75-F were 1 mg/l. DISCUSSION The fire-suppressnt foms tested were more toxi thn the nonfom fire retrdnts. Phos-Chek WD-881 nd Silv-Ex were t lest 10 times more toxi thn the fire retrdnts FT GTS-R, FT LCG-R, nd PC D75-F. Bsed on the hzrd rnking presented y Pssino nd Smith [32] ( mg/l, extremely toxi; mg/l, highly toxi; 1 10 mg/l, modertely toxi; mg/l, slightly toxi; 100 1,000 mg/l, prtilly hrmless; nd greter thn 1,000 mg/l, reltively hrmless), oth PC WD-881 nd Silv-Ex were onsidered modertely toxi formultions. GTS-R nd PC D75-F were rnked s prtilly hrmless formultions, wheres FT LCG-R ws rnked s reltively hrmless. However, the fire-retrdnt formultions re used in highly onentrted solutions in the field (e.g., the mix rtio for FT GTS-R is 1.66 l/gllon, or 198,930 mg/l); hene, the possiility of onentrtions lose to the 96-h LC50 in the environment re rel nd render the terms prtilly nd reltively hrmless in this senrio to e irrelevnt. Surftnts Toxiity of the fire-suppressnt foms PC WD-881 nd Silv-Ex is proly due to the nioni surftnt portion of their formultions. Vrious uthors hve reported on the toxiity of surftnts, with results omprle to the 96-h LC50s determined in this study. Müller [33] reported 24-h LC50 for 8-g rinow trout of 8.5 mg/l for ommeril, nonioni surftnt. Müller determined tht surftnt toxiity ws relted to the surfe tension redution used y the surftnt. The greter the redution in surfe tension, the greter the toxiity of the surftnt. In Müller s study, surfe tension ws redued to pprox. 45 to 50 dyne/m t the 24-h LT50 (the onentrtion t whih 50% of the popultion survives exposure for the speified time period). In omprison, the 0.6% Silv-Ex field pplition mixture hs surfe tension of dyne/m [19], out hlf the surfe tension redution tht used the mortlity reported y Müller [33]. Holmn nd Mek [34] determined the 96-h LC50s for three different hin-length liner lkylenzene sulfonte (LAS) nioni surftnts with 2- to 3-monthold fthed minnow (Pimephles promels) juveniles tested in soft wter (40 mg/l s CCO 3 ). The 96-h LC50s rnged from 0.86 to 12.3 mg/l, with inresing lkyl hin length diretly inresing toxiity. Although the ext nioni surftnts used in PC WD-881 nd Silv-Ex were not known, the 96-h LC50 of the LAS nioni surftnt with men hin length of C 11.7 (12.3 mg/l) [34] ws extremely lose to the 96-h LC50s determined in this study with nonegg life stges for Silv-Ex nd PC WD-881 (10 22 mg/l; Tle 3). The effet of wter qulity on the toxiity of fire-suppressnt foms, whih re primrily omposed of nioni surftnts, ws somewht ontrditory in our study. No effet ws oserved in tests with PC WD-881, wheres the toxiity of Silv-Ex ws signifintly inresed in hrd wter tests with four of the five life stges ompred to soft wter tests. Others hve lso reported onfliting results. Hoknson nd Smith [35] nd Holmn nd Mek [34] showed tht the toxiity of the nioni surftnt LAS ws inresed in hrd wter, wheres MKim et l. [36] onluded tht wter hrdness plyed minor role in the toxiity of LAS. Un-ionized mmoni, nitrte, nd nitrite The toxiity of the three fire retrdnts seemed to depend on the mount of un-ionized mmoni ville from the formultion. Little or no un-ionized mmoni ws present in the two fire-suppressnt foms. Ammoni estimtes were ompred to the un-ionized mmoni 96-h LC50 onentrtions determined y Thurston nd Russo [4], who used rinow trout in their tests. Due to the predition of extremely high onentrtions of un-ionized mmoni t 96-h LC50 for tests onduted with rinow trout eyed eggs nd emryo lrve, these life stges were not ompred to the NH 3 dt of Thurston nd Russo [4]. Estimted un-ionized mmoni onentrtions t the 96-h LC50 in tests with FT LCG-R in oth soft nd hrd wter nd the swim-up fry nd 60- nd 90-dph juveniles were very similr to those reported y Thurston nd Russo [4]. This similrity of results for the three life stges suggests tht the un-ionized mmoni derived from the mmonium polyphosphte omponent of FT LCG-R ws the primry toxi omponent. Likewise, the similrity of estimted NH 3 onentrtions t the 96-h LC50 for FT GTS-R with those reported y Thurston nd Russo [4] strongly suggests tht the un-ionized mmoni derived from the mmonium sulfte nd dimmonium phosphte omponents of FT GTS-R ws the primry toxi gent. Al-

7 Fire-retrdnt toxiity to rinow trout Environ. Toxiol. Chem. 15, Tle 6. Summry of reported ute toxiities of fire-fighting hemil formultions to rinow trout Formultion Men weight (g) ness (mg/l) Temperture (C) 96-h LC50 (mg/l) Referene GTS-R GTS-R LCG-R FIREFOAM 103B Phos-Chek D75-R Phos-Chek WD-881 Phos-Chek WD-861 Silv-Ex Silv-Ex , , [16] [17] [11] [14] [13] [15] [47] LC50 Medin lethl onentrtion. Dt not ville. C. Chng (Chemonis, personl ommunition). though PC D75-F tests in soft wter hd the lowest un-ionized mmoni estimtes of the three retrdnts tested (Tle 4), NH 3 estimtes were within ftor of two to four of the vlues reported y Thurston nd Russo [4] for similrly sized fish. This similrity suggests tht un-ionized mmoni proly ontriuted sustntilly to the toxiity of PC D75-F. Other omponents (orrosion inhiitors, olornts, et.) my hve lso ontriuted some toxiity to the formultions. Few studies hve reported the toxiity of nitrte to fish euse it is onsidered essentilly nontoxi [37]. Westin [38] reported 96-h LC50 of 1,362 mg NO 3 -N/L for rinow trout, whih is out 1,000-fold higher thn tht reported y Kinheloe et l. [39], who oserved out 50% mortlity in rinow trout fry exposed for 30 d to nitrte nitrogen onentrtions of 1.1 to 2.3 mg/l. Kinheloe et l. [39] reported toxiity vlues tht lie within the rnge reported here, ut their tests were onduted for more thn 30 d. This result my e omprle euse Weston [38] reported tht toxiity vlues delined 20% in 7-d test from tht in 96-h test. Conentrtions of nitrte nitrogen present in test wters with the three fire retrdnts t the 96-h LC50 onentrtions were elow those reported y Westin [38] for rinow trout nd proly did not sustntilly influene the toxiity of the fire-retrdnt hemils. Nitrite nitrogen proly influened the toxiity of the fireretrdnt hemils to rinow trout. Nitrite nitrogen onentrtions mesured t the 96-h LC50 onentrtions in tests with swim-up fry of rinow trout nd lulted for other life stges in tests with FT GTS-R nd FT LCG-R were greter thn those reported for rinow trout y Russo nd Thurston [40] ( mg NO -N/L), Russo et l. [41] ( mg NO -N/L), 2 2 nd Russo et l. [42] ( mg NO 2 -N/L). The mesured onentrtion of nitrite nitrogen in PC D75-F in the 96-h LC50 onentrtion for the swim-up fry life stge ws similr to those reported in the literture nd my hve ontriuted to the toxiity of the fire retrdnt in this life stge. Effet of life stge The life stge t whih rinow trout were exposed to the vrious fire-fighting hemils plyed signifint role in the toxiity of the formultion. Eyed eggs were lwys muh more resilient thn the lter life stges, possily due to their protetive ell lyers. Differenes in memrne permeility nd metoli pthwys my enle the emryo to withstnd hemil stressor euse it is isolted somewht from the quti environment. Other uthors hve reported tht rinow trout eggs were less tolernt of NH 3 thn ws reported in our study. Solé nd Shuren [43] reported tht rinow trout eggs exposed within 24 h of fertiliztion to s little s mg NH 3 /L were more sensitive thn other life stges; however, eyed eggs 24 d postfertiliztion exposed to 0.22 mg NH 3 /L hd no signifint mortlity. The older ge of the eyed eggs used in our study proly ounts for the inresed NH 3 resiliene ompred to tht reported y Solé nd Shuren [43] nd my lso indite tht eggs exposed t n erlier developmentl stge to fire suppressnts my e more sensitive s well. Solé nd Shuren [43] lso used flow-through exposure tht ontinuously replenished mmoni onentrtions, whih were mesured dily, wheres our tests were stti. The ontinuous replenishment my hve lso ontriuted to the greter sensitivity reported y Solé nd Shuren [43]. The most sensitive life stge in our tests ws the swim-up fry. This life stge is just eginning to tively serh for food nd hnge metoli proessing from endogenous to exogenous resoures, whih proly use it to e more prone to the stresses pled on it y the test formultion. Also, euse this life stge hs just egun to utilize exogenous resoures, it proly does not hve lrge store of endogenous resoures or physiologil mehnism in ple to del with this dditionl stressor. Another possiility is tht the gills of this life stge hve undergone vrious physiologil hnges in response to metoli shifts. Ammoni in its un-ionized form psses freely ross the gill epithelium [44]. Gills of rinow trout swim-up fry re presumly quite different thn those of s fry, in whih muh of the gs exhnge is omplished utneously [45]. Cutneous respirtion my provide eggs nd s fry with the ility to ope with stressor whih ffets gs exhnge in swim-up fry. Comprison to pulished nd mnufturer dt Due to the puity of toxiity informtion on fire-fighting hemils, most of the omprisons mde were with results reported y the mnufturers or y their ontrt lortories. Aville toxiity dt for rinow trout exposed to fire-fighting hemils re summrized in Tle 6. Our results for tests with FT LCG-R re similr to those reported for rinow trout tested y others with FT LCG-R [17] or with 931 [8,10], n mmonium-sed retrdnt similr to FT LCG-R exept for the mnufturer of the polyphosphtes. Johnson nd Snders [10] lso reported tht the s fry nd swim-up fry were more sensitive thn fingerling slmonids in their study, s ws generlly found in our study. Our results with FT GTS-R re similr to results of tests with rinow trout reported y others using the sme ompound [16]. In ontrst, our results with PC D75-F suggest rinow trout

8 1372 Environ. Toxiol. Chem. 15, 1996 M.P. Gikowski et l. re more sensitive thn others report (Tle 6). Aute toxiity tests onduted y Monsnto s ontrt lortory with PC D75-R, liquid similr to PC D75-F exept for the olornt, resulted in 96-h LC50 of greter thn 1,000 mg/l [12]. Their 96-h LC50 vlue ws 4.3 times our 96-h LC50 otined for 60-dph juvenile rinow trout tested in soft wter (234 mg/l) nd 4.6 times the 96-h LC50 for 60-dph juveniles exposed to PC D75-F in hrd wter (218 mg/l). This mount of vrition is greter thn the typil rnge of four for interlortory omprison of ute toxiity vlues [46]. The results of our tests onduted with the two fom suppressnts, PC WD-881 nd Silv-Ex, re similr to those of others who lso tested rinow trout [14,15,47]. Our results were lso similr to those of tests of PC WD-861, whih is similr to PC WD-881 ut ontins omponent to redue visosity in old tempertures [13] (Tle 6). However, ute toxiity tests y others with Silv-Ex produed 96-h LC50s rnging from 0.07 to 320 mg/l for severl tests with rinow trout [47]. The extreme points of the rnge were not explined, nor were desriptions of the test proedures given for ll tests. Reltion to environmentl onditions Applition of nonfom retrdnts in fire-fighting situtions is omplished y use of wide vriety of irrft equipped with different storge tnks, door sizes, nd sequening speeds, whih results in wide rnge of drop ptterns [48]. Drop ptterns nd the resulting ground ptterns re lso modified y drop height, retrdnt type, reltive humidity, temperture, nd wind speed nd diretion. Although there hs een sustntil effort to improve delivery of fire retrdnt in fixed-wing irrft, the lrge numer of omintions of irrft types nd tnk onfigurtions, retrdnt types, nd environmentl onditions preludes strightforwrd omprison of lortory toxiity dt to potentil effets in quti eosystems. Nevertheless, the wide vriety of irrft delivery systems hve een modified to deliver similr mounts of fire-fighting hemils. Retrdnt use rnges from 0.41 L/m 2 (1 gllon/100 ft 2 [gp]) for fires in nnul nd perennil grsses or tundr to 2.44 L/m 2 (6 gp) for fires in mixed hprrl or hevy slsh [48]. For exmple, the fire retrdnt FT GTS-R is prepred for field use y mixing 1.66 l/gllon wter to produe 1.1 gllons of slurry (referred to y fire fighters s field mixture), whih is equivlent to 198,930 mg/l. Field mixtures for other fire-fighting hemils re given in Tle 7. Compring the onentrtions of field mixtures to the ute toxiity vlues for the most sensitive life stge nd FT GTS-R gives rtios of 548 in soft wter nd 961 in hrd wter. Thus, n identl drop of FT GTS-R in n quti environment would require dilution of 548- to 961-fold to reh onentrtion equivlent to the 96-h LC50, onentrtion whih would use sustntil mount of mortlity. Similrly, pplition of FT LCG-R would hve to e diluted to t lest 297- to 310-fold to reh onentrtion equl to the 96-h LC50; for PC D75-F the dilution would hve to e 515- to 660-fold. A sfety ftor my e pplied to toxiity dt to estimte sfe onentrtion for quti orgnisms. The sis for sfety ftor is the sme rtionle s n pplition ftor, i.e., the rtio of the highest no-oserved-effet onentrtion (NOEC; lower limit of the mximum eptle toxint onentrtion) to the ute toxiity vlue (i.e., the 96-h LC50 [49]. An pplition ftor of 0.01 is typilly used, whih inversely gives 100 s sfety ftor to use in estimting possile NOEC. Applying sfety ftor of 100 to the ove toxiity informtion Chemil Tle 7. Formultion of field mixtures for five fire-fighting hemils nd the rtio of the onentrtion of the mixture to the ute toxiity vlue for rinow trout swim-up fry GTS-R LCG-R Phos-Chek D75-F Phos-Chek WD-881 Silv-Ex 1.66 l/gl Field mixture 1 gl/4.5 gl 1.20 l/gl 1% (v/v) 1% (v/v) (mg/l) 198, , ,800 10,000 10,000 Wter type Rtio to 96-h LC Weight or volume of hemil onentrte omined with wter to produe pplition mixture. Rtio: field mixture/medin lethl onentrtion (LC50) (mg/l). would require 96,100-fold dilution of FT GTS-R in hrd wter, 31,000-fold dilution for FT LCG-R, nd 66,000-fold dilution for PC D75-F to pproh sfe onentrtion (NOEC). Fom suppressnts re pplied t out 1% fom, whih is equivlent to 10,000 mg/l. Compring the onentrtion of field mixtures to the ute toxiity vlues for the two fom suppressnts for rinow trout gives rtios of 769 in soft wter nd 909 in hrd wter for PC WD-881, nd, for Silv-Ex, 500 in soft wter nd 769 in hrd wter (Tle 7). Applying sfety ftor of 100 to these vlues would require 76,900- to 90,900-fold dilution for PC WD-881 nd 50,000- to 76,900-fold dilution for Silv-Ex to pproh sfe onentrtion. Protetion of importnt fishery resoures from the dverse effets of fire-fighting hemils depends on dequte plnning efore fire ours, inluding identifition of strem setions tht need to e proteted nd development of pplition plns to minimize dverse effets on the strem [50]. Smll strems with little flow ould e severely ffeted y n identl fire ontrol hemil drop due to insuffiient dilution. For exmple, during the 1988 fires in Yellowstone Ntionl Prk, n identl drop of mmoni phosphte retrdnt on the Little Firehole River resulted in lmost omplete mortlity of trout [3]. Soon fter the fire, ded trout were lso found in three reek dringes, ut the use ws unknown. Toxiity tests with lrvl utthrot trout (Onorhynhus lrki) exposed over 3-week period to sh lehte from the Yellowstone fire showed no ute toxiity, thus suggesting tht sh lehte ws not the use of the fish mortlity [3]. CONCLUSIONS Rnking of the formultions tested indited tht the firesuppressnt foms were more toxi thn the fire retrdnts. The possile thret posed y fire-fighting hemils to quti eosystems should not e dismissed euse their pplition onentrtions re muh greter thn the ute toxiity vlues reported here; thus, oth formultion types my hve sustntil impt on n quti hitt. Comprison of the tests onduted in oth wter types indited tht FT GTS-R nd Silv-Ex were more toxi in hrd wter thn in soft. Further study of the impt of these formultions in vrious wter types nd in field studies my e neessry efore the influene of wter qulity on their toxiity is fully understood.

9 Fire-retrdnt toxiity to rinow trout Environ. Toxiol. Chem. 15, The eyed-egg life stge ws the lest sensitive life stge tested, wheres the swim-up fry ws generlly the most sensitive life stge. Timing nd plement of the fire-ontrol hemil pplitions my e ritil to mortlity in ertin speies. Bsed on our results, pplition during the eyed-egg life stge my result in lower mortlity thn pplition during the fry life stge. Wter ontmintion used y fire-ontrol hemils during the slmonid swim-up fry period ould e devstting to the lol popultion, espeilly if the speies is endngered s re severl western slmonids. AknowledgementThis study ws sponsored y the Interior Fire Coordinting Committee, U.S. Deprtment of the Interior. We thnk Yuhlong Lio nd Kren Olmsted for their sttistil dvie; Art Bullrd, Mrv Ehlers, Rhel Hrris, nd Joel Reynolds for their ssistne in test setup nd dt olletion; nd Kren Ferer nd Trish Gikowski for typing the mnusript nd its numerous drfts. REFERENCES 1. Vn Meter, W.P. nd C.E. y Prediting effets on fish of fire retrdnts in strems. Reserh Pper INT-166. U.S. Deprtment of Agriulture, Forest Servie, Ogden, UT. 2. Dodge, M Nitrte poisoning, fire retrdnts, nd fertilizers Any onnetion? J. Rnge Mnge. 23: Minshll, G.W. nd J.T. Brok Oserved nd ntiipted effets of forest fire on Yellowstone strem eosystems. In R.B. Keiter nd M.S. Boye, eds., Greter Yellowstone Eosystem. Redefining Ameri s Wilderness Heritge. Yle University Press, New Hven, CT, USA, pp Thurston, R.V. nd R.C. Russo Aute toxiity of mmoni to rinow trout. Trns. Am. Fish. So. 112: Singh, H.R., A.K. Doriyl nd R.C. Pokhriyl Toxiity of dimmonium phosphte to the hillstrem minor rp Brilius endelisis (Hmilton). Uttr. Prdesh. J. Zool. 5: Prmnik, A. nd S.K. Srkr Comprtive study of the sensitivity of egg, spwn nd fry of Cyprinus rpio exposed to mmonium sulphte t different tempertures. Geoios 14: Sheehn, R.J. nd W.M. Lewis Influene of ph nd mmoni slts on mmoni toxiity nd wter lne in young hnnel tfish. Trns. Am. Fish. So. 115: Blhm, T.H. nd G.R. Snyder Effet of hemil fire retrdnts on the survivl of juvenile slmonids. Report CT2-85(N) U.S. Bureu of Lnd Mngement, Denver, CO. 9. Inmn, R.C Aute toxiity of Phos-Chek (trde nme) 202 nd dimmonium phosphte to fthed minnows. Report AD/A U.S. Air Fore Environmentl Helth Lortory, Sn Antonio, TX. 10. Johnson, W.W. nd H.O. Snders Chemil forest fire retrdnts: Aute toxiity to five freshwter fishes nd sud. Tehnil Pper 91. U.S. Deprtment of the Interior, Wshington, DC. 11. Anlytil Bio-Chemistry Lortories Aute toxiity of PC-D75R to fthed minnows (Pimephles promels). Contrt Report Monsnto, St. Louis, MO, USA. 12. Anlytil Bio-Chemistry Lortories Aute toxiity of PC-D75R to rinow trout (Slmo girdneri). Contrt Report Monsnto, St. Louis, MO, USA. 13. Anlytil Bio-Chemistry Lortories Aute toxiity of PC-WD861 to rinow trout (Slmo girdneri). Contrt Report Monsnto, St. Louis, MO, USA. 14. Anlytil Bio-Chemistry Lortories Aute toxiity of PC-WD881 to rinow trout (Slmo girdneri). Contrt Report Monsnto, St. Louis, MO, USA. 15. Springorn Bionomis hour ute (LC50) with rinow trout. Contrt Report BW Wormld CDN, Thurso, PQ, Cnd. 16. Chemonis Industries GTS-R mteril sfety dt sheet. Phoenix, AZ, USA. 17. Chemonis Industries LCG-R mteril sfety dt sheet. Phoenix, AZ, USA. 18. Monsnto Compny Phos-Chek WD-881 fire suppressnt fom ft sheet. Monsnto Wildfire Division, Ontrio, CA, USA. 19. Ansul Fire Protetion Extinguishing gent dt sheet, Silv-Ex Clss A fire ontrol onentrte. Mrinette, WI, USA. 20. Shloohm, P. nd R. Rohn An evlution of fom s fire suppressnt is ville. In Fom Applitions for Wildlnd nd Urn Fire Mngement, Vol. 1. U.S. Deprtment of Agriulture, Wshington, DC, pp Fogels, A. nd J.B. Sprgue Comprtive short-term tolerne of zerfish, flgfish, nd rinow trout to five poisons inluding potentil referene toxints. Wter Res. 11: Amerin Soiety for Testing nd Mterils Stndrd guide for onduting ute toxiity tests with fishes, mroinvertertes, nd mphiins. E In Annul Book of ASTM Stndrds, Vol Phildelphi, PA, USA, pp Amerin Puli Helth Assoition, Amerin Wter Works Assoition nd Wter Pollution Control Federtion Stndrd Methods for the Exmintion of Wter nd Wstewter, 17th ed. Amerin Puli Helth Assoition, Wshington, DC. 24. U.S. Environmentl Protetion Ageny Methods for hemil nlysis of wter nd wstes. EPA 600/ Cininnti, OH. 25. Monsnto Compny Monsnto mteril sfety dt. Phos- Chek fire retrdnt, grdes D-75F nd D-75R. St. Louis, MO, USA. 26. Gikowski, M.P The ute toxiity of three fire-retrdnt nd two fire-suppressnt fom formultions to the erly life stges of rinow trout (Onorhynhus mykiss) nd fthed minnow (Pimephles promels). M.A. thesis, University of South Dkot, Vermillion, SD, USA. 27. Hh Compny Hh Wter Anlysis Hndook, 2nd ed. Lovelnd, CO, USA. 28. Peltier, W.H. nd C.I. Weer Methods for mesuring the ute toxiity of effluents to freshwter nd mrine orgnisms. EPA 600/ U.S. Environmentl Protetion Ageny, Cininnti, OH. 29. Conover, W.J Prtil Nonprmetri Sttistis, 2nd ed. John Wiley & Sons, New York, NY, USA. 30. Sprgue, J.B. nd A. Fogels Wth the Y in iossy. In W.R. Prker, E. Pessh, P.G. Wells nd G.F. Westlke, eds., Proeedings, 3rd Aquti Toxiity Workshop, Hlifx, NS, Cnd, Novemer 2 3, pp Zr, J.H Biosttistil Anlysis. Prentie Hll, Englewood Cliffs, NJ, USA. 32. Pssino, D.R.M. nd S.B. Smith Aute iossys nd hzrd evlution of representtive ontminnts deteted in Gret Lkes fish. Environ. Toxiol. Chem. 6: Müller, R Fish toxiity nd surfe tension of non-ioni surftnts: Investigtions of ntifom gents. J. Fish. Biol. 16: Holmn, W.F. nd K.J. Mek An quti sfety ssessment of liner lkylenzene sulfonte (LAS): Chroni effets on fthed minnows. Trns. Am. Fish. So. 109: Hoknson, K.E.F. nd L.L. Smith, Jr Some ftors influening toxiity of liner lkylte sulfonte (LAS) to the luegill. Trns. Am. Fish. So. 100: MKim, J.M. J.W. Arthur nd T.W. Thorslund Toxiity of liner lkylte sulfonte detergent to lrve of four speies of freshwter fish. Bull. Environ. Contm. Toxiol. 14: Russo, T.C Ammoni, nitrite, nd nitrte. In G.M. Rnd nd S.R. Petroelli, eds., Fundmentls of Aquti Toxiology: Methods nd Applitions. Hemisphere, New York, NY, USA, pp Westin, D.T Nitrte nd nitrite toxiity to slmonoid fishes. Prog. Fish. Cult. 36: Kinheloe, J.W., G.A. Wedemeyer nd D.L. Koh Tolerne of developing slmonid eggs nd fry to nitrte exposure. Bull. Environ. Contm. Toxiol. 23: Russo, R.C. nd R.V. Thurston The ute toxiity of nitrite to fishes. In Reent Advnes in Fish ToxiologyA Symposium. EPA 600/ U.S. Environmentl Protetion Ageny, Corvllis, OR, pp Russo, R.C., R.V. Thurston nd K. Emerson Aute toxiity of nitrite to rinow trout (Slmo girdneri): Effets of ph, nitrite speies, nd nion speies. Cn. J. Fish. Aqut. Si. 38: Russo, R.C., C.E. Smith nd R.V. Thurston Aute toxiity of nitrite to rinow trout (Slmo girdneri). J. Fish. Res. Bord Cn. 31: Solé, J.F. nd D.G. Shuren Toxiity of mmoni to erly life stges of rinow trout (Slmo girdneri). Wter Res. 23: Rndll, D.J. nd P.A. Wright The intertion etween