United States
Environmental Protection
Agency
Office of Research and
Development
Washington DC 20460
EPrV600/R-99«)98
September 1999
Assessing Contaminant
Sensitivity of
Endangered and
Threatened Species:
Toxicant Classes

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                                                            EPA/600/R-99/098
                                                             September, 1999
     Assessing  Contaminant Sensitivity
Of Endangered  and  Threatened Species:
                   Toxicant Classes
                                by
   F. James Dwyer1, Douglas K. Hardesty, Christopher E. Henke, Christopher G. Ingersoll,
              David W. Whites, David R. Mount2, Christine M. Bridges
              U.S. Geological Survey, Biological Resources Division
                   Columbia Environmental Research Center
                4200 New Haven Road, Columbia, Missouri 65201
         1 Current address: U.S. Fish and Wildlife Service, 608 East Cherry St.,
                      Room 200, Columbia, MO 65201
      2Current address: U.S. Environmental Protection Agency, 6201 Congdon Blvd.,
                           Duluth, MN 55804
                     EPA Project No. DW14936559-01-0
                     Project Officer, Foster L. Mayer, Jr.
                         Gulf Ecology Division,
                        Gulf Breeze, Florida 32561
                    U.S. Environmental Protection Agency
                  National Health and Environmental Effects
                          Research Laboratory
                          Gulf Ecology Division
                      Gulf Breeze, Florida 32561-5299
                                                        Printed on Recycled Paper

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                                                Abstract

    Under the Federal Insecticide, Fungicide and Rodenticide Act, the Toxic Substances Control Act and the Clean
Water Act, the U.S. Environmental Protection Agency (EPA) is charged with determining if the manufacture, use, or
disposal of a chemical will present an unreasonable risk of harm to the environment. Typically, management decisions
are based on protecting populations of organisms.  However, the Endangered Species Act requires that, in some
cases, managers must estimate the take of individuals to determine if the loss of individuals might adversely affect a
population of an endangered or threatened (listed) species.  The most direct assessment would be to determine the
sensitivity of a listed species to a particular contaminant or perturbation. However, this direct approach would be time
consuming and expensive because it might require development of organism culturing and handling procedures, some
species may not be amenable to culture, there might be multiple species to be considered, and would be contaminant
specific.

    It is not possible to test all listed species that may need protection from environmental contaminants. Therefore,
decisions need to be made for listed species using toxicity data obtained from standard test procedures and using.
surrogate organisms typically tested in laboratory toxicity assessments (e.g., rainbow trout Oncorhynchus mykiss,
fathead minnow Pimephales promelas, and the cladoceran Ceriodaphnla dubia). These surrogate species are easily
tested using standardized methods; however, there is concern that these species or procedures may not adequately
represent populations of listed species.  By evaluating the sensitivity for a number of listed species, it is possible to
make generalizations regarding the protection afforded  listed species through standard regulatory programs. This
research project had two objectives: (1) determine the relative sensitivity to contaminants of listed species using
standard acute toxicity tests; and (2) determine the degree of protection afforded listed fish species through the use of
standard species used in whole effluent toxicity tests.

    Previous cooperative research conducted between the EPA and U.S. Geological Survey primarily evaluated the
similarity in response to five chemicals with different modes of action (carbaryl, copper, 4-nonylphenol,
pentachlorophenol and permethrin) between surrogate (rainbow trout and fathead minnows) and listed species within
the same taxonomic family (Salmonidae, Cyprinidae) using standard acute toxicity tests. The present study expands
this data base by testing five additional species with these five chemicals.  Species were listed either by the U.S. Fish
and Wildlife Service (FWS) or state agencies or were species identified as surrogates in FWS Recovery Plans.
Organisms included: (1) the Family Percidae fountain darter (Etheostoma rubrum, Federally listed), greenthroat darter
(Etheostoma lepidum,  state listed - Texas); (2) the Family Acipenseridae, shovelnose sturgeon (Scaphirhynchus
platorynchus, identified as surrogate for the Federally listed pallid sturgeon - Scaphirhynchus albus); (3) the Family
Poeciliidae, Gila topminnow (Poeciliopsis occidentalis,  Federally listed); and (4) the Family Bufonidae, boreal toad
tadpoles (Bufo boreas, state listed - Colorado).

    The data we have generated indicates that in 96-h acute toxicity tests, if rainbow trout is used as a test species, a
species typically used  in pesticide registration or water quality criteria derivation, those procedures which protect the
rainbow trout would likely be protective of most listed aquatic fish species.  If a safety factor is heeded to estimate 96-
h LC50s for listed fish species, our data indicates that 0.5 would be a conservative estimator.  Also, if EPA water quality
criteria are recalculated by eliminating certain species from the  data set, such as rainbow trout, then listed fish species
might not be adequately protected.
                                                     Ill

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                                               Notice

    The U.S. Environmental Protection Agency through its Office of Research and Development (funded and managed
or partially funded and collaborated in) the research described here under EPA Project No. DW14936559-01-0 to U.S.
Geological Survey, Biological Resources Division, Columbia Environmental Research Center. It has been subjected to
the Agency's peer and administrative review and has been approved for publication as an EPA document.


                                      Acknowledgements

    The authors thank Dr. Foster L. Mayer, Jr. of the Gulf Ecology Division, U.S. Environmental Protection agency for
his guidance and assistance in this project. We thank Eugene Greer for culturing the test organisms and Nile Kemble,
Eric Brunson, Jill Soener, and Heather Willman of the Toxicology Branch of the Columbia Environmental Research
Center for their assistance during this project.  We thank Tom Brandt of the San Marcos National Fish Hatchery and
Technology Center, Jerry Hamilton of the Blind Pony Missouri State Hatchery, Roger Hamman of the Dexter National
Fish Hatchery, and Kirsta Scherff of the Colorado Division of Wildlife for supplying organisms tested in this study. We
thank ICI Americas, Inc., and Rhodia, Inc. for donating technical grade material to be used in testing. We also thank
Charles Stephan (EPA, Duluth, MN), Anne Keller (EPA, Athens, GA) and Linda Sappington (USGS, Columbia, MO) for
their critical review of this report.
                                                   IV

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                                     Contents

Abstract	;	  jjj

Acknowledgments	  jv

    Introduction	  1
    Materials and Methods	;	  1
         Test Organisms	  1
         Chemicals	  2
         Toxicity Tests	  3
         Water Quality	  3
         Statistical Analysis	  4

    Results and Discussion	  4
         Management Implications	8

    References	  9

    Appendix
         Appendix 1     Exposure water pH	10
         Appendix 2     Exposure water dissolved oxygen	10
         Appendix 3     Acute toxicity data for present study	 11
         Appendix 4     Acute toxicity data for other listed species	 13

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Introduction

Under the Federal Insecticide, Fungicide and Rodenticide
Act, the Toxic Substances Control Act and the Clean Water
Act, the U.S. Environmental Protection Agency (EPA) is
charged with determining whether the manufacture, use, or
disposal of a chemical will present an unreasonable risk of
harm to  the  environment.    Typically,  management
decisions are  based  on  protecting  populations  of
organisms.   However,  the Endangered  Species Act
requires that, in some cases, managers must estimate the
take of individuals to determine if the loss  of individuals
might adversely affect a population of an endangered  or
threatened (listed) species. The most direct assessment
would be to determine the sensitivity of a listed species to
a particular contaminant or perturbation. However, this
direct approach would be time consuming and expensive
because it might require development of organism culturing
and handling  procedures,  some  species  may not be
amenable to culture, there might be multiple  species to be
considered, and would be contaminant specific. Therefore,
it is not possible to test all listed species that might need
protection from environmental contaminants.

An indirect approach for determining the sensitivity of listed
species would .be to use  toxicity data obtained from
standard test procedures and using surrogate organisms
typically tested  in laboratory toxicity assessments (e.g.,
rainbow trout (Oncorhynchus mykiss), fathead minnow
(Pimephales promelas),  bluegill (Lepomis macrochirus).
These  surrogate  species  are  easily tested   using
standardized methods (EPA 1975, ASTM 1998); however,
there is concern that these species or procedures may not
adequately represent population of listed  species. By
evaluating the sensitivity for a number of listed species, it
is   possible  to  make  generalizations  regarding the
protection afforded  listed  species through  standard
regulatory programs.

Previous cooperative research conducted by the EPA and
U.S. Geological Survey (EPA 1995) primarily  evaluated the
similarity  in sensitivity  between  surrogate  and  listed
species within the same taxonomic family. Acute toxicity
tests were conducted for  96 h with the rainbow trout,
fathead minnow, and the following listed species: Apache
trout (Oncorhynchus apache),  Lahontan cutthroat trout
(Oncorhynchus clarkihenshawi), greenback cutthroat trout
(Oncorhynchus clarki  stomias),  bonytail  chub  (Gila
elegans), Colorado squawfish (Ptychocheilus lucias), and
razorback sucker  (Xyrauchen texanus).    Endpoints
evaluated included mortality at 3, 6, 9, 12, 18, 24, 48, 72,
and 96 h of exposure. Chemicals tested included: carbaryl,
copper, 4-nonylphenol, pentachlorophenol, and permethrin.
These chemicals were selected  to  represent different
chemical classes and toxic modes of action. Results from
these studies indicated that the standard test organisms
(rainbow trout and fathead minnow) often had a similar
sensitivity to toxicant exposure as the listed salmonid and
cyprinid species.  However, for about 30% of the possible
surrogate/listed species comparisons, the listed species
was more sensitive than the standard surrogate species of
the same family.

The objective of the present study was to expand this acute
toxicity data base by conducting tests on the same five
chemicals with five additional species.  The selection of
species tested in the  present study  was  based  on
availability of listed organisms. Species were listed either
by  the U.S. Fish and  Wildlife  Service (FWS) or state
agencies,  or were species identified as surrogates in the
FWS Recovery Plan.  Organisms evaluated in the present
study included: (1) Percidae - fountain darter (Etheostoma
rubrum, Federally listed), greenthroat darter (Etheostoma
lepidum,   state  listed  -  Texas);  (2)  Acipenseridae -
shovelnose  sturgeon   (Scaphirhynchus  platorynchus,
identified  as surrogate for  the Federally listed  pallid
sturgeon - Scaphirhynchus albus); (3) Poeciliidae - Gila
topm]r\r\ow(Poeciliopsisoccidentalis, Federally listed); and
(4)  Bufonidae-boreal toad tadpoles (Bufo boreas, state
listed-Colorado). Toxicity tests were attempted with the
shortnose  sucker  (Chasmistes  brevirostris,  Family
Catostomidae, Federally listed), but this species exhibited
excessive mortality during test acclimation and therefore
was not tested.  Toxicity tests  have been successfully
conducted elsewhere with shortnose suckers of the same
size used  in this study  (L. Cleveland, USGS, Columbia,
MO, personal communication).   We  believe  that this
particular lot of fish was inferior because handling and
acclimation  to test conditions  resulted in substantial
mortalities.

Materials and Methods

Test organisms
Fountain   darters,  greenthroat  darters,   shovelnose
sturgeon, gila topminnow, and boreal toads were obtained
from various federal and state sources during 1995 and
1996 (Table 1).  The fishes were received as fry and the
toads were received as tadpoles.

Fishes and tadpoles were held in well water (alkalinity 258
mg/L as CaCO3, hardness 286 mg/L as CaCO3, pH 7.8,
18°C) at the Columbia  Environmental Research Center
(CERC, Columbia, MO) until acclimation began. Before the
start of a toxicity test, organisms were acclimated for a total
of 96 h (EPA 1975,  ASTM 1998).  For the  first  48 h,

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organisms  were  acclimated  to the  test  water  and
temperature.  The test organisms were then moved to
clean containers and held for an additional 48 h at the test
temperature in 100% test water. Organisms were not fed
during the 48 h of holding in 100% test water.

Chemicals
The chemicals used in testing were carbaryi, copper, 4-
nonylphenol, pentachlorophenol, and permethrin (Table 2).
Chemicals were selected to represent different classes of
chemical and modes of toxic action.  Organic chemical
stock solutions were prepared by dissolving the chemical
in reagent grade  acetone,  whereas  stock solutions for
copper were prepared by dissolving copper in deionized
water. The maximum acetone concentration in any test
container was 0.05 mL/L.
                                Organic and inorganic chemical stocks were analyzed to
                                confirm nominal concentrations. Organic chemical analysis
                                was  conducted  at either  Mississippi  State  Chemical
                                Laboratory (Mississippi State, MS) or ABC Laboratories
                                (Columbia, MO) using  gas  chromatography.   Copper
                                stocks were confirmed at either the CERC or Mississippi
                                State   Chemical   Laboratory  by   atomic  absorption
                                spectrophotometry. Overall, the  mean percent nominal
                                concentration was 110% (n = 9), with a mean range of 63%
                                (copper) to 160% (permethrin).  One 4-nonylphenol stock
                                had a percent nominal concentration  of 320%.  However,
                                biological results from the tests using these stocks were
                                similar to tests conducted with other 4-nonylphenol stocks.
                                Therefore, we believe the reported value for this sample is
                                incorrect and that percent recovery was not included in the
                                average percent of nominal concentration.
      Table 1.  Source and size of test organisms used in toxicity tests.

            Species           Scientific Name                Source
                                                                 Size
      Fountain darter
      Greenthroat darter
Etheostoma rubrum
Etheostoma lepidum
      Shovelnose sturgeon    Scaphirhynchus
                          platorynchus
San Marcos National Fish Hatchery and   62 mg +19
Technology Center, San Marcos, TX      20.2 mm ± 2.0

San Marcos National Fish Hatchery and   133 mg + 19
Technology Center, San Marcos, TX      22.6 mm + 0.4

Blind Pony Missouri State Fish          719 mg ± 237
Hatchery, Sweet Springs, MO           60.1 mm ± 0.8
      Gila topminnow


      Boreal toad
Poeciliopsis occidentals  Dexter National Fish Hatchery,
                     Dexter, NM
Bufo boreas
Colorado Division of Wildlife, collected
from the West Fork of Clear Creek, near
Georgetown, CO
219mgi65
27.2 mm + 2.6

all tests except carbaryi -12 mg
(mean of 20 weighed as group)
9.6 mm ± 0.7 carbaryi - class 2
(about 200 mg)
       Table 2. Source, percent active ingredient, use and mode of action for chemicals used in toxicity tests.
Chemical
Carbaryi
Copper sulfate
4-nonyIphend
Pentachlorophenol
Permethrin
Source
Donated by Rhone-Poulenc
Agricultural Co., Research
Triangle Park, NC
Fisher Chemical, St. Louis, MO
Fluka Chemical, New York, NY
Aldrich Chemical, Milwaukee,
Wl
Donated by ICI Americas Inc.,
Richmond, CA
Active
Ingredient (%)
99.7
25.5
85.0
99.0
95.2
Use
carbamate
insecticide
mining,
industrial,
fungicide
nonylphenol
ethoxylate
detergents
wood
preservative,
molluscicide
pyrethroid
insecticide
Mode of Action
inhibitor of cholinesterase
activity
interferes in
osmoregulation
narcotic and oxidative
stressor
uncoupler of
oxidative
phosphorylation
neurotoxin


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 Toxicity tests
 Static acute  toxicity tests were  conducted  in basic
 accordance with procedures described in EPA (1975) and
 ASTM (1998). Exposures were conducted in 19.6-L glass
jars containing  15  L of test  solution.   All  tests were
 conducted at 22°C.  Test water was reconstituted hard
 water (alkalinity 110 to120 mg/L as CaCO3, hardness 160
 to180 mg/L as CaCO3- ASTM  1998).  One study with the
 boreal toad was conducted in CERC well water.  Tests
were conducted under ambient lighting.

The exposure series consisted of six concentrations with a
 60% dilution series tested in duplicate (except for the tests
with the boreal toad, which were tested in triplicate). When
a solvent was used, both a solvent control and a  dilution
water control were included for each species. Individual
test series were randomly assigned to  a waterbath  and
location within a waterbath (complete block design).

Fishes and tadpoles were counted into two groups (3 to 5
organisms per group depending on availability) and pooled
            for each exposure replicate (7 to 10 organisms/replicate).
            Mortality was the endpoint measured at 6, 12, 24, 48, 72,
            and 96 h of exposure and was defined as lack of move-
            ment for a  5-s observation with the unaided eye. Dead
            animals were removed at each observational time.  The
            study design for each species is summarized in Tables.

            Carbaryl concentrations used in the test conducted with the
            boreal toad tadpoles were not high enough to estimate LC50
            concentrations.    Subsequent  testing with  boreal toad
            tadpoles was being performed concurrently with this study.
            In that testing, exposures were conducted in the well water
            used for culture and the carbaryl testing had a 70% dilution
            series.  All other conditions were similar.

            Water quality
            Alkalinity, hardness, and pH were measured on each batch
            of reconstituted water before the start of the exposures.
            Alkalinity and hardness of reconstituted hard water were
            within suggested ranges, but average pH (8.4) was slightly
            above the suggested value of 8.0 (Table 4).
             Table3. Summary of study design for the comparative toxicity of selected chemicals to listed species.
             Test Type:

             Static Acute

             Test Volume:

             Test Temperature:

             Water Quality:


             Chemicals:


             Dilution Series:

             Replicates/number of organisms
             per replicate:



             Observations:
Static acute

15L

15 L

22°C

Reconstituted ASTM hard (alkalinity 110 to 120
mg/L as CaCO3, hardness 160 to 180 mg/L as CaCO3)1

Carbaryl, copper, 4-nonylphenol, pentachlorophenol, permethrin

60%

Fountain darter - 2 replicates/10 fish per replicate Greenthroat darter
- 2 replicates/7 fish per replicate
Shovelnose sturgeon - 2 replicates/9 fish per replicate
Gila topminnow - 2 replicates/10 fish per replicate
Boreal toad - 3 replicates/10 tadpoles per replicate

Mortality at 6, 12, 24, 48, 72, and 96 h of exposure
             1Carbaryl exposures with boreal toads were conducted in well water.
                        Table 4. Average (± standard deviation)
                        Water Quality Characteristic
                        1mg/L as CaCO3
      Nominal Value
                         Measured (n = 4)
Alkalinity1
Hardness1
pH
110-120
160-180
7.8 - 8.0
115 + 1
167 + 5
8.4 + 0.1

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The pH was measured on the control, low, medium, and
high exposure concentrations at 0 h and in those same
treatments if organisms survived to 96 h of exposure. Test
chemicals spiked into the test water altered pH , but not in
a consistent  pattern.  Appendix! lists the pH which
represents the lowest and highest pH measured for all
exposure concentrations and replicates within a test at the
start and end of the exposure.

Dissolved oxygen was measured  on the control,  low,
medium, and high exposure concentrations at 0 h and in
those same treatments if organisms survived to 48 and 96
h of exposure.  Appendix  2 is  a list of the exposure
replicates and concentrations for which dissolved oxygen
was below 60% saturation at 48 h of exposure  or below
40% saturation at 96 h of exposure. Any drop in dissolved
oxygen was  isolated and  interspersed throughout the
exposures.  However, in toxicity tests with shovelnose
sturgeon, jars with acetone added either as a control or as
a chemical carrier had low concentrations  of dissolved
oxygen at 48 h of exposure.  The low concentrations of
dissolved oxygen in those jars may have been the cause
for the mortalities observed in that test at 72 h of exposure.
For this reason, data generated from toxicity tests with
shovelnose sturgeon using solvent carriers should be
interpreted with caution.  We did not include any toxicity
data for shovelnose sturgeon toxicity tests using acetone
as a carrier solvent beyond 48 h of exposure.

Statistical Analysis
The LCjo and 95% confidence interval for each test was
usually calculated using probit analysis. However, when
probit analysis  was not appropriate (i.e., less  than two
partial mortalities), LC^s and confidence intervals were
calculated  using  moving   average   or   a non-linear
interpolative procedure (Stephan 1977).  The LC50s and
confidence  intervals  were  determined  using  nominal
concentrations.
                                       t
In the previous study conducted by the EPA and USGS
(EPA 1995) six different  tests (3 replicates per test) for
each  of the five chemicals  were conducted  with  the
rainbow trout and fathead minnow and two different tests
for the six listed species.    In that  study, similar test
conditions  were  used  (static  acute  toxicity  tests,
reconstituted hard water and 60% dilution series) with
coldwater species  being  tested at 12°C and warmwater
species tested at 22°C.

In  the  previous study,  statistical tests  to determine
differences between species used analysis of variance and
least  square mean separations on ranked LC50s (EPA
1995).  For the present study, we did not have multiple
tests  for the listed species. Therefore to compare listed
species responses to rainbow trout, an overall LC50 and
confidence interval for each chemical was calculated for
rainbow trout by combining all replicates from the six tests.
The  LCgoS for fountain  darters, greenthroat darters,
shovelnose sturgeon, gila topminnow,  and boreal toads
calculated in the present study were then compared to the
overall LCSO for rainbow trout. Differences between LC50s
were tested for statistical significance using the procedure
described by Sprague and Fogels (1976).

Results and Discussion

Control survival, with and without solvent, was always
greater than 90% for all species except the shovelnose
sturgeon  (Table 5). Appendix 3 is a listing of all  LC50s and
confidence intervals for  each  chemical,  species,  and
observation time period.

In the toxicity tests with fountain darters, average control
survival without acetone was 97% and  with acetone was
93%.  However, there was a 5 to 15 % mortality in most
low (below observed concentration-effect curve) exposure
concentrations, regardless of the chemical  tested.

Tables 6  to 10 summarize the 12, 24 and 96 h LC50s for all
five chemicals and each species. In general,  at 96 h of
exposure, permethrin was the most toxic compound and
carbaryl was the least toxic compound. These results were
similar.to those reported in the previous study  (EPA 1995).
The   two  phenolic  compounds  (4-nonylphenol  and
pentachlorophenol) and copper  had LC50s  in a  similar
range of  concentrations.

Consistent with previous studies (Macek  and  McAllister
1970, EPA 1982, Birge and Black 1982, Blank  1984, Mayer
and  Ellersieck  1986, Reish  1988)  no  one species was
always the most sensitive species  to  ail chemicals.
Generally, of the  listed species, the fountain darter was
more  sensitive  to  contaminant  exposure  than  the
greenthroat darter, shovelnose sturgeon, Gila topminnow,
or boreal toad.  After  '96 h of exposure, LC50s for the
fountain  darter were similar to rainbow trout LCsos for
carbaryl  (Table 6),  pentachlorophenol (Table  9) and
permethrin (Table 10). The LC^s for fountain  darters were
less than those for rainbow trout for copper (Table 7) and
4-nonylphenol (Table 8), however the LC50s were within a
factor of  0.6.

The boreal toad was generally more  resistant than the
rainbow   trout   with  LC50s   for  carbaryl,  copper,
pentachlorophenol and  permethrin statistically greater (1.5
- 6.5 times) than the LCSO for rainbow trout.  In contrast, the
4-nonylphenol  LCSO  for boreal  toad  tadpoles  was
significantly less than the LC^ for rainbow trout.  These
taxonomic comparisons are consistent with the findings of
Mayer and Ellersieck  (1986).   They determined that
amphibians (western chorus- frog - Pseudacris triseriata
and Fowler's  toad  -  Bufo woodhouseri fowleri) were

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       Table 5.  Average control survival for listed species. All survival is at 96 h of exposure except
       where noted.
Species
Fountain darter
Greenthroat darter
Shovelnose sturgeon
Gila topminnow
Boreal toad
Control Survival without
Solvent (%)
97
100
48 h- 100
96 h- 100
100
100
Control Survival with Solvent
(%)
93
93
48 h- 100
96h-0
100
100
    Table 6.  Acute toxicity of carbaryl (mg/L) at 12, 24, and 96 h of exposure.  Also included are the
    geometric means of LC50s (n=6) for rainbow trout and fathead minnows tested using similar test
    conditions (EPA 1995). An asterisk (*) indicates the LC50 for the listed species is significantly
    different (p < 0.05) than the LC50 for rainbow trout.  LC50s for fathead minnows are provided for
    reference purposes.
Species
Fountain darter
Greenthroat darter
Shovelnose sturgeon
Gila topminnow
Boreal toad2
Rainbow trout
Fathead minnow
' 12-h LC50
>3.0
>3.0
4.90*
>3.0
>21
6.76
12.00
24-h LCso
>3.0
>3.0
3.60
>3.0
>21
4.04
8.25
96-h LCso
2.02
2.14
nc1
>3.0
12.31*
1.88
5.21
    1nc = not calculable
    2toxicity test with boreal toad was conducted in well water
Table 7.  Acute toxicity of copper (mg/L) at 12, 24, and 96 h of exposure. Also included are the geometric
means of LC50s (n=6) for rainbow trout and fathead minnows tested using similar test conditions (EPA 1995).
An asterisk (*) indicates the LC50 for the listed species is significantly different (p < 0.05) than the LC50 for
rainbow trout.  LC50s for fathead minnows are provided for reference purposes.
Species
Fountain darter
Greenthroat darter
Shovelnose sturgeon
Gila topminnow
Boreal toad
Rainbow trout
Fathead minnow
12-h LC50
0.24*
>0.3
>0.6
>0.3
0.19*
0.40
1.30
24-h LC50
0.15*
>0.3
0.54*
>0.3
0.16*
0.12
0.73
96-h LC50
0.06*
0.26*
0.16*
0.16*
0.12*
0.08
0.47

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      Table 8. Acute toxicity of 4-nonylphenol (mg/L) at 12, 24, and 96 h of exposure. Also included are
      the geometric means of LC50s (n=6) for rainbow trout and fathead minnows tested using similar test
      conditions (EPA 1995).  An asterisk (*) indicates the LC50 for the listed species is significantly
      different (p < 0.05) than the LC50 for rainbow trout. LCMs for fathead minnows are provided for
      reference purposes.
Species
Fountain darter
Greenthroat darter
Shovelnose sturgeon
Gila topminnow
Boreal toad
Rainbow trout
Fathead minnow
12-h LC50
>0.25
>0.25
0.25
>0.25
0.12*
0.35
0.38
24-h LC50
0.21*
0.23*
0.20*
>0.25
0.12*
0.30
0.33
96-h LC60
0.11*
0.19
<0.13
0.23*
0.12*
0.19
0.27
      Tables. Acute toxicity of pentachlorophenol (mg/L) at 12, 24, and 96 h of exposure. Also included
      are the geometric means of LC50s (n=6) for rainbow trout and fathead minnows tested using similar
      test conditions (EPA 1995). An asterisk (*) indicates the LC^ for the listed species is significantly
      different (p < 0.05) than the LC50 for rainbow trout. LC50s for fathead minnows are provided for
      reference purposes.
Species
Fountain darter
Greenthroat darter
Shovelnose sturgeon
Gila topminnow
Boreal toad
Rainbow trout
Fathead minnow
12-h LCso
0.20*
0.31*
0.16*
>0.7
>0.7
0.22
0.33
24-h LC60
0.17
0.30*
<0.13
0.64*
>0.42
0.17
0.30
96-h LC50
0.11
0.18
nc1
0.34*
0.37*
0.16
0.25
      1nc = not calculable

Table 10. Acute toxicity of permethrin  (ug/L) at 12, 24, and 96 h of exposure. Also included are the
geometric means of LC^ (n=6) for rainbow trout and fathead minnows tested using similar test conditions
(EPA 1995). An asterisk (*) indicates the LC50 for the listed species is significantly different (p < 0.05) than
the LCOT for rainbow trout.  LC50s for fathead minnows are provided for reference purposes.
Species
Fountain darter
Greenthroat darter
Shovelnose sturgeon
Gila topminnow
Boreal toad
Rainbow trout
Fathead minnow
12-h LC60
5.60
3.10*
>10.0
>10.0
>10.0
5.75
13.43
24-h LC60
4.26
2.71*
nc1
>10.0
>10.0
3.78
9.73
96-h LC50
3.34
2.71*
nc1
>10.0
>10.0
3.31
9.38
'nc = not calculable

-------
generally the more resistant taxonomic group compared to
either rainbow trout or fathead minnows.  Results from the
present study indicate that in acute exposures the boreal
toad is  generally more resistant than the rainbow trout.
The boreal toad LC50s are also greater than the LC50s for
fathead minnows exposed to carbaryl, pentachlorophenol,
or permethrin but less  than  the LC50s for the fathead
minnow exposed to copper or 4-nonylphenol.

For the following discussion we have included data from
the  present study  and data  generated in   previous
cooperative research conducted between the  EPA and
USGS (EPA 1995)  for the  same  five chemicals with
rainbow trout, fathead  minnows and six different  listed
species  -  Apache  trout,  Lahontan  cutthroat  trout,
greenback  cutthroat  trout,  bonytail  chub,  Colorado
squawfish, and razorback sucker. Toxicity data for these
tests at 12,24, and 96 h of exposure are listed in Appendix
4.  In order to evaluate species sensitivity, within a
chemical, we ranked 96-h LC50s for each species, from 1
(high  sensitivity) up to 13 (low sensitivity). Ranks were
then averaged across chemicals for each species (Table
11).   There were four listed species  (Apache  trout,
greenback cutthroat trout, fountain darter, and Lahontan
cutthroat trout)  that were overall more sensitive than the
rainbow trout, while, overall the fathead minnow was the
least sensitive species.
   Table 11.  Rank of species sensitivity using 96-h LC50s. Within a chemical, the most sensitive species (lowest LC50) was assigned a rank of
   1 whereas the least sensitive species was assigned a rank up to 13 (highest LC50). Ranks were then averaged across chemicals for each
   species.
Species
Rainbow trout
Fathead minnow
Fountain darter
Greenthroat darter
Shovelnose sturgeon
Gila topminnow
Boreal toad
Apache trout
Greenback cutthroat trout
Lahontan cutthroat trout
Bonytail chub
Colorado squawfish
Razorback sucker
Carbaryl
3
10
4
5
not ranked
not ranked
11
1
2
6
8
7
9
Copper
4'
12
1
9
6.5
6.5
5
2.5
not ranked
2.5
8
11
10
Nonylphenol
7.5
11
1
7.5
not ranked
9
2
4.5
3
6
12
10
4.5
PCP1
3
7
1.5
5
not ranked
9
10
1.5
not ranked
4
5
6
8
Permethrin
4
7
5
3
not ranked
not ranked
not ranked
2
not ranked
1
not ranked
8
6
Average
Rank
4.3
9.4
2.5
5.9
6.5
8.2
7
2.3
2.5
3.9
8.3
8.4
7.5
   1 - pentachlorophenol

In addition to relative species sensitivity, the magnitude of
difference between LC50s is also important.  Using data
from the previous study for the six rainbow trout tests with
each  chemical (EPA  1995),  we calculated  two factors
(lowest 96-h LC50/mean 96-h LC50; mean 96-h LC50/highest
96-h LC50) which encompassed the range of LC50s for that
chemical. For example, for the six toxicity tests conducted
with rainbow trout and carbaryl (EPA 1995), the lowest 96-
h LC50 was 1.22 mg/L, the highest 96-h LCSO was 3.11, and
the mean 96-h  LC50  was  1.88 mg/L.  Hence, factors
calculated for rainbow trout carbaryl exposures were 0.60
and 0.65 with a geometric mean of 0.62.    For the five
chemicals tested with rainbow trout, the geometric mean
factor for all five chemicals was 0.69 with a range of 0.60
(permethrin) to 0.80 (pentachlorophenol). We followed the
same  procedure  for fathead  minnows and the  five
chemicals.  Fathead  minnows  had an geometric mean
factor for the five chemicals of 0.65 with a range of 0.57
(pentachlorophenol) to 0.73 (permethrin). If a factor of 0.67
is selected as representative of the normal range in LC50
(expected range = LC50X0.67 to LCSO/0.67) for a specific
chemical  and  species,  then the  sensitivities of listed
species can be evaluated in terms of how often 96-h LC50s
for the listed species differed by more than a factor of 0.67

-------
 from the  96-h  LC^ for either rainbow trout or fathead
 minnows.
sensitive  to  many other chemicals,  were  much  less
sensitive to TFM (Cairns 1986).
 For the 11 listed species tested there were 48 comparisons
 that could be made to rainbow trout and 46 comparisons to
 fathead minnows.  When a factor of 0.67 is applied to the
 geometric mean LC^ for each of the five chemicals tested
 With rainbow trout, 24 LC^s for listed species are outside
 this range but only 4 LC^s are  less than the expected
 range of LC^s for rainbow trout.  When the factor  of 0.67
 is applied to the  geometric  mean  LC50 for the five
 chemicals tested relative to fathead minnows, there are 31
 LCajS for listed species outside the range with 28 of the 31
 LCjoS less than the expected range of LC50s for the fathead
 minnow.  The comparison of rainbow trout and fathead
 minnows  includes species  from both Salmonidae and
 Cyprinidae and five additional families (4 fish  and  1
 amphibian  -  Percidae,   Acipenseridae,  Poeciliidae,
 Bufonidae,  and   Catostomidae) and   included  tests
 conducted at 12 and 22°C. In only 8% of the comparisons
 to rainbow trout (4 of 48)  was a listed  species more
 sensitive than rainbow trout. This would indicate that for
 acute environmental assessments, toxicity data for rainbow
 trout  are  generally similar to or  protective of listed fish
 species.

 Endangered species may require an additional degree of
 protection since their populations are already in decline and
 any additional loss of individuals may lead to extinction.
 The previous discussion has shown that the rainbow trout
 is generally more sensitive than the fathead minnow and
 that listed species are frequently  more sensitive than
 fathead minnows.  Also, only 4 of 48 tests with a listed
 species had an LC^ less than a factor of 0.67 from that of
 the rainbow trout. A final evaluation would be to determine
 the greatest difference  between the  96-h LC^s  of the
 rainbow trout and a listed species. Within a chemical, we
 compared the lowest 96-h LC^ for a listed species to the
 geometric mean 96-h LC^j for rainbow trout.  For  all five
 chemicals, at least one listed species had a 96-h LC50
 lower than the 96-h LC^ for rainbow trout.  There were a
 total of 16 LCgoS for listed species that were less than the
 comparable LC^ for rainbow trout. The average difference
was about 0.8 and the maximum difference was about 0.5.

Management Implications
 Previous studies have found that no one species is always
the most or least sensitive to contaminant exposure (i.e.
Macek and McAllister 1970, EPA 1982, Birge and Black
 1982, Blank 1984, Mayer and Ellersieck 1986, Reish 1988)
and therefore a species is the best surrogate only for itself
(Mount 1982).  For example, the sea lamprey, generally
considered insensitive to contaminant exposure, was found
to be the  species most sensitive to the lampricide TFM
while many desirable fish species, generally considered
Mayer and Ellersieck (1986) determined that fish LC50s for
a  given  chemical varied  as much as  nine  orders  of
magnitude. Blanck (1984) used data from various literature
sources and found that chemical sensitivity of algae varied
by seven orders of magnitude.  Birge and Black (1982)
reported LC50s for five or more aquatic species exposed to
50 different organic or inorganic toxicants. They found that
LC50s differed by one  order of magnitude for 33% of the
cases studied, and  up to three orders of magnitude for
another 33% of the cases.  Macek and McAllister (1970)
reported the 96-h LC50s for 12 species (five families) varied
by up  to four orders of magnitude depending on the
chemical. In the present study, we did not find the same
degree of variability reported in these previous studies.
However, the  potential variability  exhibited  in these
previous studies emphasizes the difficulties that must be
faced when attempting to determine the potential impact of
contaminants on a listed species.

The  EPA Standard Evaluation Procedure for Ecological
Risk Assessment for pesticides and endangered species
requires stringent criteria for estimating risk (EPA 1985).
A  formal consultation  is required  if the  expected
environmental concentration is greater than "1/1 Oth the
lowest aquatic acute LC10 (when a slope is available)  or
greater than  1/20th the lowest aquatic LC50 (when no slope
is  available)".  While  the  risk assessment document
provides guidance on when a consultation must take place,
there is  no  guidance provided  on  how  contaminant
sensitivity should be  evaluated.   Ultimately,  the  FWS
biologists responsible for the risk assessments will decide
if there is substantial risk to the species.  However, our
data would indicate that if a conservative approach is used
for protecting listed fish for which there is no toxicity data,
a factor of 0.5 could be applied to the geometric mean LC50
of rainbow trout toxicity data and an estimated  LC50 for a
listed  species  could  be   determined.     Expected
environmental concentrations  or target environmental
concentrations could then be compared to this calculated
number and  an evaluation of the risk to the species could
be made.

Finally,  the  data we  have generated indicates that if
rainbow trout is used as a test species, a species typically
used in  pesticide registration or water quality criteria
derivation, those procedures which protect the rainbow
trout would likely be protective of most listed aquatic fish
species.  However, as previously discussed, if a factor is
needed to estimate LC^s for listed fish species, our data
indicates that 0.5 would  be  a conservative estimator.
Finally, if EPA water quality criteria are recalculated by
eliminating certain species from  the data set, such as


-------
rainbow trout, then listed species might not be adequately
protected.

In summary, only direct testing will provide specific
information regarding protection of listed species.  Our
laboratory has  evaluated only  11  aquatic vertebrate
species (mostly fish) and there are currently over 90 fishes
listed by the FWS.  The  database for fishes should be
expanded to include a few. additional species from different
areas of the United States. Amphibian population declines
have been recognized worldwide and the FWS has over 10
listed species; therefore, greater emphasis should also be
placed on testing amphibian species.  Testing is also
needed to evaluate sublethal effects of contaminants on
listed  species.   Finally, other listed species, including
freshwater mussels and other  invertebrates, should be
examined.

References

American Society  for Testing  and Materials.   1998.
  Standard guide for conducting acute toxicity tests on test
  used in toxicity tests.
Birge, W.J. and J.A. Black. 1982. Statement on surrogate
  species  cluster   concept.   In  U.S.  Environmental
  Protection Agency. 1982. Surrogate species workshop.
  TR-507-36B.
Blanck, H.  1984  Species dependent variation among
  aquatic organisms in their • sensitivity to  chemicals.
  Ecological Bulletin. 36:107-119.
Cairns,  J. Jr.  1986.  The myth  of the most sensitive
  species. BioScience 36:670-672.
Macek, K.J.  and W.A. McAllister.  1970.   Insecticide
  susceptibility   of   some   common   fish   family
  representatives. Trans. Am. Fish. Soc. 99:20-27.
Mayer, F.L., Jr., and M.R, Ellersieck. 1986.  Manual of
  Acute Toxicity: Interpretation and  Data Base for 410
  Chemicals and 66 Species of Freshwater Animals. U.S.
  Fish Wild. Serv. Resour. Publ. 160. 579 p.
Mount, D. 1982. Aquatic surrogates in U.S. Environmental
  Protection Agency. Surrogate species workshop. TR-
  507-36B.
Reish,  D.J.  1988.  The use of toxicity testing in marine
  environmental research. Chapter 10. ln:D.F. Souleand
  G.S.  Kleppel (eds.), Marine organisms as indicators.
  Springer-Verlag, New York, pp. 213-245.
Sprague, J.B. and  A. Fpgels. 1977.   Watch the Y in
  Bioassay.  Proceedings 3rd Aquatic Toxicity Workshop,
  Halifax, N;S. Nov 2-3, 1976. Environmental Protection
  Service Technical Report
Stephan, C.E. 1977.  Methods for calculating an LC50. ]n:
  F.L. Mayer and J.L. Hamelink (eds.) Aquatic Toxicology
  and  Hazard Evaluation, ASTM  STP  634, American
  Society for Testing and Materials.
U.S. Environmental Protection Agency. 1975. Methodsfor
  acute toxicity tests with fish, macroinvertebrates, and
  amphibians.  EPA 660/3-75-009. Ecological Research
  Series, Washington, D.C. 61 p.
U.S. Environmental Protection Agency. 1982. Surrogate
  species workshop.  TR-507-36B.
U.S. Environmental Protection Agency.  1986. Standard
  evaluation procedure: Ecological risk assessment.
  EPA  540/9-85-001. Hazard Evaluation Division, Office
  of Pesticide Programs, Washington, D.C. 96 p.
U.S. Environmental Protection Agency.  1995. Use of
  surrogate species in assessing contaminant risk to
  endangered and threatened fishes. EPA 600/R-
  96/029.  Office of Research and Development. Gulf
  Breeze,  FL. 78 p.

-------
           Appendix 1.  Exposure water pH for each test (species and chemical) at 0 and 96 h. The pH
           range represents the lowest and highest pH measured for all exposure concentrations  and
           replicates within a test.
Species
Fountain darter




Greenthroat darter




Shovelnose sturgeon




Giia topminnow




Boreal Toad




Chemical
carbaryl
copper
4-nonylphenol
pentachlorophenoi
permethrin
carbaryl
copper
4-nonylphenol
pentachlorophenoi
permethrin
carbaryi
copper
4-nonyiphenol
pentachlorophenoi
permethrin
carbaryl
copper
4-nonylphenol
pentachlorophenoi
permethrin
carbaryl
copper
4-nonylphenol
pentachlorophenoi
permethrin
Oh
7.9-8.3
8.1-8.3
8.3
8.3-8.4
8.3
7.8-8.0
7.7-7.9
7.7-7.9
7.8-7.9
7.8-7.9
8.4
8.2-8.4
8.1-8.4
8.3-8.4
8.3-8.5
7.2-8.0
7.9-8.1
7.7-8.1
7.6-8.1
6.8-7.4
7.9-8.1
7.7-8.1
7.5-8.3
7.4-8.1
8.0-8.1
96 h
7.8-8.2
8.1-8.2
8.0-8.1
7.9-8.1
8.0-8.1
7.9-8.2
8.2-8.3
8.0-8.2
7.6-8.2
7.9-8.3
nm1
6.8-7.4
6.7
nm
7.3
7.9-8.0
8.0-8.1
8.0
8.0-8.1
8.0-8.1
nm1
7.7-8.1
7.9-8.0
7.8-8.1
7.9-8.1
          'nm - not measured

Appendix 2.  Exposure replicates (rep) and concentrations (cone) for which dissolved oxygen was below 40% saturation
(22°C - 5.2 mg/L) at 48-h of exposure or below 60% saturation (22°C - 3.5 mg/L) at 96 h of exposure.
Species
Fountain darter
Greenthroat darter
Shovelnose sturgeon






Gila topminnow












Boreal toad

Chemical
pentachlorophenoi
pentachlorophenoi
carbaryl

copper
4-nonylphenol
permethrin


carbaryl



4-nonylphenol



pentachlorophenoi

permethrin
,

carbaryl

rep
1
2
1
2
1
1
1

2
1

2

2

1

2
1
1
1

2
3
cone
low
medium
low
low
medium
low
low
medium
low
medium
high
medium
high
low
medium
medium
high
medium
low
low
low
high
low
low
48h


3.5
4.4

3.3
3.1
3.3
4.4




4.8
5.0


4.8

5.0




96h
3.0
1.3


2.9




2.4
1.9
2.8
2.5


2.5
3.2

2.1

1.8
3.1
2.3
2.9
                                                    10

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Appendix 3. Calculated LC50, 95% confidence interval for each chemical, species and time period. LC50s and confidence intervals were
calculated using probit analysis unless otherwise noted.

                                                        Carbaryl (mg/L)
Species
Boreal toad
Shovelnose sturgeon
Greenthroat darter
Fountain darter
Gila topminnow

Species
Boreal toad
Shovelnose sturgeon
Greenthroat darter
Fountain darter
Giia topminnow

Species
Boreal toad
Shovelnose sturgeon
Greenthroat darter
Fountain darter
Gila topminnow
Hours
6 12 24 48
>21 >21 >21 . >21

72
12.31b
(10.3-14.7)
>10 4.90 3.60C 1.75 <1.3
(4.20-5.72) (2.16-6) (1.46-2.05) Complete mortality
>3.0 >3.0 3.0 2.84
(2.38-4.03)
>3 >3C >3C 2.77b
(1.8-3.0)
>3 >3 >3 >3
Copper (mg/L)
Hours
6 . 12 24 48
>0.3 0.19 0.16b 0.14
(0.11-0.3) (0.11-0.18) (0.13-0.15)
>0.6 >0.6 0.54 0.38
(0.44 - 0.78) (0.30 - 0.56)
>0.3 >0.3 >0.3 0.27
(0.23 - 0.35)
>0.3 0.24" 0.15" 0.08
(0.18-0.3) (0.11-0.18) (0.07-0.10)
>0.3 >0.3 >0.3 >0.3
4- nonylphenol (mg/L)
Hours
6 12 24 48
0.19" 0.12b 0.12b 0.12b
(0.15-0.25) (0.09-0.15) (0.09-0.15) (0.09-0.15)
0.38 0.25" 0.20 0.20
(0.34-0.44) (0.13-0.36) (0.17-0.22) (0.17-0.22)
>0.25 >0.25 0.23" 0.22"
(0.15-0.25) (0.15-0.25)
>0.25C >0.25 0.21" 0.1 7b
(0.15-0.25) (0.15-0.25)
>0.25 >0.25 >0.25 >0.25
2.44
(1.94-3.65)
2.07b
(1.08-3.0)
>3


72
0.14
(0.13-0.15)
0.21
(0.16-0.28)
0.26"
(0.18-0.3)
0.06
(0.05 - 0.07)
0.23"
(0.18-0.3)


72
0.12b
(0.09-0.15)
<0.13
0.20b
(0.15-0.25)
0.13a
(0.11 -0.15)
>0.25

96
12.31"
(10.3-14.7)
<1.3
Complete mortality
2.14
(1.73-2.88)
2.02b
(1.08-3.0)
>3


96
0.12b
(0.07-0.18)
0.16
(0.12-0.21)
0.26"
(0.18-0.3)
0.06
(0.05 - 0.07)
0.1 6a
(0.14-0.19)


96
0.12"
(0.09 - 0.15)
<0.13
0.19"
(0.15-0.25)
0.11b
(0.09-0.15)
0.23"
(0.15-0.25)
"-moving average
b-nonlinear interpolation
°-binomial test
                                                               11

-------
Appendix 3, (Continued).
Pentachlorophenol (mg/L)
Species
Boreal toad
Shovelnose sturgeon
Greenthroat darter
Fountain darter
Glla topmtnnow

6
>0.7
0.27
(0.24 - 0.30)
0.33"
(0.25 - 0.42)
0.34
(0.30 - 0.38)
>0.7

12
>0.7
0.16
(0.14-0.19)
0.31"
(0.25 - 0.42)
0.20
(0.18-0.22)
>0.7
Hours
24
>0.42
<0.13
0.30"
(0.25 - 0.42)
0.17a
(0.04-0.21)
0.64"
(0.42 - 0.70)

48
0.54"
(0.42 - 0.70)
—
0.28b
(0.25 - 0.42)
0.18
(0.17-0.20)
0.51"
(0.42 - 0.70)

72
0.52"
(0.42 - 0.70)
—
0.18"
(0.15-0.25)
0.16"
(0.09 - 0.25)
0.36b
(0.25 - 0.42)

96
0.37"
(0.25 -0.42)
—
0.1 8b
(0.15-0.25)
0.11b
(0.09-0.15)
0.34"
(0.25 - 0.42)
Permethrin (ug/L)
Species

6

12
Hours
24

48

72

96
     Boreal toad
     Shovelnose sturgeon
10
Greenthroat darter
Fountain darter
GHa topminnow
4.31
(3.71 - 5.04)
>10C
>10
3.10"
(2.20 - 3.60)
5.60
(4.76 - 6.67)
>10
2.71
(2.36-3.13)
4.26a
(3.58-5.19)
>10
2.71
(2.36-3.13)
3.34a
(2.75-4.16)
>10
2.71
(2.36-3.13)
3.34a
(2.75-4.16)
>10
2.71
(2.36-3.13)
3.34a
(2.75-4.16)
>10
    * - moving average
    b - nonlinear interpolation
    '-binomial test
                                                                12

-------
Appendix 4.  Acute toxicity of carbaryl (mg/L) to 8 species of fish (2 surrogate and 6 listed) at 12-, 24-
and 96-h of exposure.  Toxicity values are the geometric mean of the LC50s (number of LCsos in
parentheses).  Data was abstracted from EPA (1995).
Species 12-h LC^
(n)
Rainbow trout 6.76
(4)
Apache trout 3.29
(2)
Greenback cutthroat 8.50
(D
Lahontan cutthroat 4.38
(2)
Fathead minnow 12.0
(1)
Bonytailchub 7.93
(2)
Colorado squawflsh >10.0
(na)1
Razorback sucker 8.88
(1)
Acute toxicity of copper (mg/L) to 8 species of fish
exposure. Toxicity values are the geometric mean
Data was abstracted from EPA (1995).
Species 12-h LC50
(n)
Rainbow trout 0.40
(3)
Apache trout 0.18
(2)
Greenback cutthroat >0.03
(na)1
Lahontan cutthroat 0.39
(2)
Fathead minnow 1 .30
(4)
Bonytail chub 0.30
(2)
Colorado squawfish >1.00
(na)1
Razorback sucker >1 .00
(na)1
24-h LC50
(n)
4.04
(6)
2.50
(2)
3.59
(D
3.60
(2)
8.25
(3)
6.13
(2)
6.31
(1)
6.67
(2)
(2 surrogate and 6 listed) at 12-,
of the LC50s (number of LC50s in
24-h LC50
(n)
0.12
(4)
0.09
(2)
>0.03
(na)1
0.11
(2)
0.73
(4)
0.24
(2)
0.64
(2)
0.39
(D
96-h LC50
(n)
1.88
(6)
1.54
(2)
1.55
(1)
2;25
(2)
5.21
(5)
3.49
(2)
3.07
(2)
. 4.35
(2)
24-, and 96-h of
parentheses).
96-h LC50
(n)
0.08
(4)
.. 0.07
(D
>0.03
(na)1
0.07 . .
(2)
.0.47
(6)
0.22
(2)
• 0.43
(2)
0.27 .
(2)
1 na = not applicable
                                            13

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Appendix 4, (conUnued).
 Acute tqxicity of 4-nonylphenol (mg/L) to 8 species offish (2 surrogate and 6 listed) at 12-, 24- and
 96-h of exposure. Toxicity values are the geometric mean of the LC50s (number of LC50s in
 parentheses).  Data was abstracted from EPA (1995).
Species
Rainbow trout
Apache trout
Greenback cutthroat
Lahontan cutthroat
Fathead minnow
Bonytail chub
Colorado squawfish
Razorback sucker
12-h LCOT
(n)
0.35
(6)
0.30
(2)
0.38
(D
0.29
(2)
0.38
(6)
0.56
(2)
0.45
(2)
0.29
(2)
24-h LC50
(n)
0.30
(6)
0.24
(2)
0.30
(D
0.25
(2)
0.33
(6)
0.49
(2)
0.28
(2)
0.22
(2)
96-h LC50
(n)
0.19
(6)
0.17
(2)
0.15
d)
0.18
(2)
0.27
(6)
0.29
(2)
0.26
(2)
0.17
(2)
Acute toxicity of pentachlorophenol (mg/L) to 8 species of fish (2 surrogate and 6 listed) at 12-, 24-
and 96-h of exposure. Toxicity values are the geometric mean of the LC50s (number of LCsos in
parentheses). Data was abstracted from EPA (1995).
Species
Rainbow trout
Apache trout
Greenback cutthroat
Lahontan cutthroat
Fathead minnow
Bonytail chub
Colorado squawfish
Razorback sucker
12-h LCM
(n)
0.22
(6)
0.21
(2)
>0.01
(na)1
0.27
(D
0.33
(6)
0.42
(2)
0.23
(2)
0.53
(2)
24-h LCa,
(n)
0.17
(6)
0.21
(2)
>0.01
(na)1
0.23
(2)
0.30
(6)
0.26
(2)
0.16
(2)
0.29
(2)
96-h LCSO
(n)
0.16
(6)
0.11
(2)
>0.01
(na)1
0.17
(2)
0.25
(6)
0.23
(2)
0.24
(2)
0.28
(2)
1 na = not applicable
                                           14


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  Appendix 4, (continued).
Acute toxicity of permethrin (ug/L) to 8 species of fish (2 surrogate and 6 listed) at 12-, 24-, and 96-h of
exposure. Toxicity values are the geometric mean of the LC50s (number of LC60s in parentheses).  Data
was abstracted from EPA (1995).
           Species
12-h LC5I
   (n)
24-h LC5(
   (n)
96-h LC50
   (n)
Rainbow trout


Apache trout


Greenback cutthroat


Lahontan cutthroat


Fathead minnow


Bonytail chub


Colorado squawfish


Razorback sucker
   5.75
   (6)

   3.88
   (2)

   >1.0
  (na)1

   3.33
   (2)

  13.43
   (4)

  >25.0
  (na)1

  >25.0
  (na)1

  13.05
   (D
  3.78
   (6)

  2.27
   (2)
     .
  (na)1

  1.93
   (2)

  9.73
   (5)

  >25.0
  (na)1

  >25.0
  (na)1

  8.87
   d)
  3.31
   (6)

  1.71
   (2)
     .
  (na)1

  1.58
   (2)

  9.38
   (6)

  >25.0
  (na)1

  24.4
   (D

  5.95
   (2)
 na = not applicable
                                                15
                                                             . GOVERNMENT PRINTING OFFICE: 2000 550-101/20014

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