EPA-600/4-81-076
                                            September 1981
        INITIAL TOXICOLOGICAL ASSESSMENT OF

    AMBUSH, BOLERO, BUX, DURSBAN, FENTRIFANIL,

    LARVIN, AND PYDRIN:  STATIC ACUTE TOXICITY

TESTS WITH SELECTED ESTUARINE ALGAE, INVERTEBRATES,

                     AND FISH        .          ..


                        by
     'Patrick W. Borthwick and Gerald E. Walsh
         Environmental Research Laboratory
       U.S. Environmental Protection Agency
            Gulf Breeze, Florida  32561
         ENVIRONMENTAL RESEARCH LABORATORY
        OFFICE OF RESEARCH AND DEVELOPMENT
       U.S. ENVIRONMENTAL PROTECTION AGENCY
            GULF BREEZE, FLORIDA  32561

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                                           ..INTRODUCTION	

'.$ ,              The sensitivity  of  estuarine  organisms  to  seven pesticides granted
           experimental  use  permits or awaiting registration was evaluated in response
           to a request  of the Office  of Pesticide Programs, Ecological Effects Branch,
           Hazard Evaluation Division, U.S.  Environmental  Protection Agency (EPA).
           Acute static  toxicity tests were  conducted with six insecticides (Ambush ,
           Bux  , Dursban , Fentrifanil , Larvin ,• and PydrinK), and one
           herbicide  (Bolero ) by the  EPA Environmental Research Laboratory,
           Experimental  Environments Branch,  at Gulf Breeze, Florida (ERL.GB).  Sources,
           .purities,  target  pests,  applications, and registration status are summarized
           in Appendix A.        v •                       ;  • -. >.

                This  report  is the  first of  a series and includes the biological effects
           "screening" data  generated  in 96-h EC50 (concentration of pesticide_that
           would inhibit growth  by  50%, as compared to  control growth in 96 h) bioassays
          -with marine algae, 48-h  EC50 (concentration  of  pesticide that would cause -50%
           of the exposed larvae to develop  abnormally  in  48 h) tests with estuarine
         .  'mollusk  larvae, and static  acute  96-h LC50 (concentration of pesticide that  '.
           is lethal  to  50%  of the  test organisms during a 96-h exposure) toxicity tests
           with estuarine crustaceans  and fish.  ' .•''"- -••- c . -  -f      :•"  *

                .....:• .       :   •  :     MATERIALS-AND METHODS    • ..     . -

        ^-^Algal Bioassays  -;•;•• :•ป"",;;: ..:;.':";/•',.:• , - •- • .•'<• •-?.-•: .-V ''•:•: ':•:•'•'-:<•••..•:    • \, ••

           Algal Species Tested  and Procedures' .;-  "     . ;   •:•',:   .   .-

              - One to four  species of algae were used  in  tests with Ambush, Bolero,
           Dursban, Larvin,  and  Pydrin.  Tests with all five pesticides were conducted
           with Skeletonema  costatum.   In additional tests, Isochrysis ga'lbana and
           Thalassiosira pseudonana were exposed to Dursban and Pydrin.  Nitzschia
           angularum  was also tested with Pydrin.  .All  were obtained from the Culture
           Collection of Algae,  University of Texas, Austin, TX, except S. costatum
           which was  obtained from the University of Rhode Island, Kingston, RI.

                Media for stock  algal  cultures and for  tests pesticides were prepared by
           dissolving a  commercial  artificial sea salt  formulation  (Rila Products,
           Teaneck, NJ*) in  deionized  water  to the concentration of 30 parts per
           thousand.  Before the solution was taken to  final volume, trace, metals,
           vitamins,  and minor  salts were added as nutrients (Apprendix B).  Medium was
           prepared on the day  before  a test was to begin  to allow the pH to stablize at
           8.1.
                                                                               •
                Algal stocks were maintained in 150 ma  of  culture medium with-EDTA^in
           500  ma Eclenmeyer flasks under the following conditions:  light intensity,
           150  uE/m /sec(PAR, 400-700  nm waveband) from overhead "cool .white"
           •B	
              Registered  trade marks, generic names and  manufacturers are  listed in
           Appendix A.   Mention  of  commercial products  or  trade names does not
           constitute endorsement by the U.S. Environmental Protection Agency.

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      *?.<:
., 'if^f -, , 'r j

.•^';~J *'ฃ' '.
„ - :• -c' '"";
•, - •# •<•-;,
"' f>;'- t" -
.- ^T,'ij. .-.
 fluorescent tubes; lighting cycle, 14  h  light  followed by 10 h darkness;
 temperature, 20.0 _+ 0.5ฐC; transfer to new  stock  medium every 10 days.  Stock
 cultures were not shaken.                  .    . •   .

      Pyrex  (Corning Glass Works,  Corning,  NY)  glassware was used and was
 prepared as follows:   (1) soaked in detergent  overnight, (2) brushed lightly,
 (3) rinsed thoroughly  in tapwater,  (4) rinsed  three  times in pesticide-grade
 acetone, (5) soaked overnight in 1% HC1,  (6) rinsed  thoroughly with
 tapwater, (7) rinsed five times with deionized  water,  (8) dried in an oven,
 and (9) stored in a relatively dust-free  container or  individually sealed
 with aluminium foil.   All glassware and  media  were sterilized by autoclaving
 at 121ฐC and 1.4 kg/cnr for 20 min.

 Bioassay Procedure   :-:	'•'••*>- '•'••' '•'••   •   -     • ••  ; •- •• • <    •.-':.•••".

". '-•''* One week prior to the tests approximately  5  ma,  of an algal culture in
 •logarithmic growth phase was added to  150 m of culture medium that contained
. ethylenediaminetetracetic acid  (EDTA), thus ensuring healthy culture in the
 logarithmic growth phase. "On the  day  of  the test, cultures were diluted with
 growth media to yield  2000 eel 1 s/mm  for SVcostatum and .1000 cells/mm   •ป)•••
 for all other species; 1 mฃ of this cell'suspension  was added to-each algal
 culture tube.--.  ; •....  -r. •-J..?     •   • .-,       -.  -.._••,.,,•.•:..•.       .
 '•'•••.- • •-In tests with pesticides, 25 ma  of culture medium without EDTA were
 pipetted into optically matched test  tubes  (25X200mm) which then were capped
 with stainless steel microbiological  closures and autoclaved.  On the second
 day, a known quality of pesticide in  0.1  mx, of acetone was added to exposure
 tubes, and 0.1 ml of nanograde acetone  was  added to control tubes.  Then 1 mi
 of algal suspension was added aseptically to each tube.'  Treated cultures as
 well as controls were  run  in triplicate.             .   .:••  ,

      Cultures were incubated while  shaking  "at approximately 60 excursions/min
 on Model G2 Gyratory shakers fitted with No. AG2-Ta25 platforms (New  ; .   .
 Brunswick Scientific Cor,  New Brunswick,  CN) under 150 pE/nr/sec PAR
 illumination from .".cool-white" fluorescent  tubes; temperature was 20.0 +_
 0.5ฐC; the "1 ighting cycle  was 14 h-of light followed by 10 h of darkness;
 test duration was 96 h.    • "              -:     --.r-
        After 96 h  incubation,  absorbances  of cultures and optical blanks were
 measured at 525 nm on  a Fisher Electrophotometer II  (.Fisher Scientific
 Co., Pittsburg, PA).

 '. •  '-•'••^Concentrattons^that  inhibited .growth' by 50% (EC50)1 and 95% confidence
 . intervaTs-were calcu:Ta'ted  by. moving .averages :on' a Digital Equipment
  Corporation.-POP-.11/7:0 computer.         .    "...    -           '
                      INVERTEBRATE  AND FISH TOXICITY TESTS
 Animal Species
      Invertebrates  and  fish  used in static acute toxicity tests were spawned
 or cultured at ERL, GB.   The parent Eastern oyster (Crassostrea virginica)

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stock was purchased from oystermen, then conditioned  and  induced  to  spawn  at
ERL, GB.  Gametes were mixed to produce <2-h-old embryos  for  48 h EC50  tests.

     Stone crab (Menippe mercenaria) zoea larvae were hatched from a gravid
female collected from Santa Rosa Sound at Sabine Island.  Mysid shrimp
(Mysidopsis bahia) <24-h-old were hatched from  brooding females from
laboratory mysid cultures isolated overnight  in a brood chamber.

     Sheepshead minnow (Cyprinodon variegatus)  brood  stock  was captured from
embayments on Santa Rosa Island, then conditioned and induced to  spawn  in  the
laboratory.  Fry for toxicity tests were reared to  28 days  of age.

Animal Food     • ,   •   •             ...

     Oyster parent stock were fed on natural  plankton assemblages in
unfiltered seawater, while oyster larvae were not fed.  Stone crab adult
females were fed raw fish muscle.  Mysid shrimp and stone crab larvae were
fed living brine shrimp (Artemia sp.) nauplii during  culture. The sheepshead
minnow brood stock diet included fresh-frozen adult Artemia and a commercial
dried flake food.  Fry were fed Artemia nauplii. *'"/'-••- ;.•..,-,.  ~  .,  ,,,  .

   • Chemical analysis .of all foods given to  brood stock or  test animals
indicated that non detectable concentrations  of chlorinated hydrocarbons less
than 0.1  (yg/g) or parts per million (ppm) wet  weight were  present.  -,.-.

     With the exception of adult oysters, which received  raw  unfiltered
seawater, all animals were spawned or cultured  in intermittent-flow seawater
filtered  through coarse sand and 10 to 20 micrometer  (ym) polypropylene-core
filters at ambient salinity and 25ฐC.  Static toxicity tests  were conducted  in
seawater  filtered through 1.0 pm polypropylene-core filters and adjusted to  20
ฐ/oo salinity by addition of Rila Salt Mix K  (Rila  Products,  Teaneck, NJ)
or deionized water.  Temperature was maintained at_25 •+_ 1ฐC in all  cultures
and toxicity tests.

Test Pesticides     .                .        .

     Pesticide samples used in this study are described in  Appendix A.
Seawater  concentrations and median effect concentrations,.of each  pesticide
are reported here as mi.crograms (yg) of pestircide!.-pe.r,rfli.tler (a) of seawater,
or parts  per billion.  All concentrations are nominal based on weight of
sample  per volume and are uncorrected for purity or specific  gravity.

Static Acute Toxicity Tests

     All  toxicity tests were conducted in accordance  with Draft Toxicity Test
Standards of the American Society of Testing  and Materials; 48-h  EC50s  for
larval  oysters in accordance with  "Standard  Practice  for  Conducting Static
Acute Toxicity Tests with Larvae of Four Species of Bivalve Molluscs" (ASTM,
1978a), and 96-h LCBOs for stone crab larvae, mysids, and fish in accordance
with the  proposed "New Standard Practice for Conducting Basic Acute Toxicity
Tests with Fishes, .Macroinvertebrates, and Amphitxians" (ASTM, 1978b).

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        During the 96-h test period, stone crab  larvae  and  mysid shrimp were fed
   48-h-old Artemia hauplii each day to minimize cannibalism  and starvation.

        Both..48-h EC50s (and 95% confidence  intervals)  for  Eastern  oyster larvae
   and 96-h LC50s (and 95% confidence intervals) for crustaceans and fish were
   calculated by either the probit, binomial, or moving averages.

              .     ;",...    RESULTS AND DISCUSSION  .   .".

      •  Results of algal bioassays (Table 1) and static acute toxicity tests
   with invertebrates and fish (Table 2) provide an initial foundation for the
   toxicological assessment of Ambush, Bolero, Bux, Dursban,  Fentrifanil,     j.
   Larvin, and Pydrin on estuarine organisms.  The 48-h EC50  for Eastern oyster-
   larvae was not determined since this species  was determined to be
   insensitive to four pesticides in a sbort-terjn acute exposure.   The estimate
 •  of toxicity (expressed as 48-h EC50 >1,000 mg'/i) provides  a confirmatory
   result.  Test concentrations >1,000 mg/ฃ  cause cross-contamination of
 -equipment and glassware and increase the  exposure hazard to workers. .When an
 .  estuarine test species -is insensitive at--1,000 mg/ฃ,^further acute testing
  jshould be continued until toxicity to several phyla  has  been determined.  :

 .•      '.the synthetic pyrethroids, Ambush and :Pydrin, were .the most toxic of the
 -  -seven pesticides tested and were extremely-.toxic to  crustaceans. '/Toxicity,._
 f,-in .decreasing order,-to algal population-growth (Table 1)  was Ambush,  ;•;-•'•
  •Dursban, Bolero, Larvin, Pydrin, and oyster larvae  (Table  2), Ambush, Pydrin,
 /  Dursban, Bolero. : Acute lethality, in decreasing order,  to crustaceans was
 'Pydrin, "Ambush;; Dursban, Fentrifanil, Bux, Larvin,'Bolero  and to fish,
 "  Fentrifanil, Bux, Ambush, Pydrin, Dursban, Larvin, Bolero. '••;-,-,-•    .  <•-•••

        Bolero, the only herbicide'tested, was less toxic than the  six
   insecticides.  Phylo'geneticany,'the descending order of-sensitivity was:
.v  -crustaceans, fish, algae, and oyster .ilarvae.  .!,./v^^Vc. ,:ซ;&.-.j, •.:;'•;?;•• :u ,..;
     -""'••    "     '          "     '   ' *•        '  '       '  '.-.'.,.'••
       -The synthetic pyrethroids'were extremely insoluble  in seawater.  In
  ..tests with algae, oyster larvae, and fish, median effects  were higher than
   the solubility in rseawater. "•.Consequently? actual- exposure concentrations of
   Ambush and Pydrin were probably much Tower than the  'dosed  nominal
   concentrations ;due to their-hydrophobia nature.  'Results of several
   pyrethroid toxicity'"tests with filsh varied, indicating that exposure
   concentrations {above- so-1 ubiTity) were fricd'nsistent  among  tests.  A
   subsequent reportrfro"rn^ERL jGB  (SchimmeT.et-ฐal. ', "1981) confirms that
   pyrethroid toxi'crties' tri< fTowihg^acute::tests;/w-ith sheepshead minnows were an
   order of ma'gnitude'Towe^'-than  in Vta'tnc ac-Ute tests  reported here.  -Since
   problems with .pyrethroid exposure cohcentTati^ons4 occurred-with fish,"" static
   acute'values-'reported here";'should"not be  considered  final'. ' Crustaceans were
   extremely sensitive to "Ambu-sh "and Pydrin  at concentrations below the limit of
   solubility in seawater.  When  compared to flowing acute-test results, static
   tests with mysid shrimp were characteristically 2 and 3  X  less sensitive.

                 . ,,,:,.   ,   •       ..        4      -.;                .   ; i

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                             REFERENCES
     American Society .for Testing and Materials, -.Committee ฃ-35  on
Pesticide's,' '1978a.  Proposed -Standard iRiractice.^d^^ondiuc.t-ing ,S.tat-ic
Basic Acute ''Toxi city Trests jWittKLarvae o.firlto.Ur.fSp.eGii>es
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Table  1.   Results  of  algal bioassays using  pesticides and  unicellular  algae.
           'Values are  the 96-h EC50s (95% confidence interval), or the
           calculated  concentration  that would  inhibit growth by 50%, as
      - -   compared  to control growth,  expressed in units of parts per
       :  'billion  (micrograms per liter).   .•
.ป ป *J> .-' * -
Pesticide
ป •' Species :: . ; - .
•'Tested" .'-'"'."'
'•'•'•-••^ Test
No.
96-h EC50 (95%CI) ^
' • ug/ฃ
 Ambush    .  , .:.Skeletonema costatum   •  ,;.;.,".'  . 1..
 .  '.   ;.'.'..,.  /,; -,v-..-;,-... ..   -.   ,.-...  -vi '•'•.-  ^

 Bolero   ; ji: - -Skeletonema costatum   ;,,];  ^;':>^:1 •'•[


      '.  •' ^i;'.'' ••->..',"',• .-'.'•' ,-.fr'; - >•-.  ป•:• •,;.:..{.•.-•  ".  ",,.- ,-jt: 4  .


"Dursban    •  v Skeletonema costatum  ; .;  •""•''*'•' !-'t
       .  ..,••     ..   .        ,          ::,;'.••""'"2  "
                          •':".••"•••'* •  ,. :. '  ••"3-
                         :•'"   "  .';' *' ••  : .  "  .'-"'4  :
                                                        .124  (104-154)
                                                         92  (  71-115)

                                                        459  (327-692)
                                                        :.410  (368-461).
                                                        327  (290-368)
                                                        377  (326-439)
                                                        :389  (338-452)
                                                        ,\"i'(" "' *','•',;' V '•''•'
                                                        :255  (228-286)
                                                        289  (257-334)
                                                        326  (283-402)
                                                        328  (290-391)
                                                        297  (268-335)

':'''-'•• ' '*-':
Larvin

Pydrin



Isochrysis'-galbaria ':' -•ป
-,ซ-... ••--' Thai assi osi ra' pseudonana
Skeletonema costatum
.
Skeletonema costatum
Isochrysis qalbana
_ Thai assi osi ra pseudonana
Nitzschia angularum

•i-l'Sr: -
1 • ' ' '
.1
2
3
4
1



138 "(112-169) .
148 (121-182)
457 (386-547)
462 (414-518)
404 (366-449)
454 (410-509)
M ,000*
>1 ,000*
>1 ,000*
>1,000*.
-ซ.
* No  effect on  growth

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Table 2.  Acute static toxicity of  pesticides to  several,estaurine  animals.  Values  are 96-h LC50
          (95% confidence interval)  or *48-h EC50  (based  on  abnormal  development) expressed in
          units of parts per billion (micrograms/liter).
Pesticide
*Crassostrea
  virginica
 <2-h larvae
 Mysidopsis
   bahia
1-d juveniles
 Menippe
mercenaria
zoea larvae
Cyprinodon
variegatus
 28-d fry
Ambush          >1,000

Bolero     1,0001,000
                  0.046(0.032-0.056)

                  370(317-433)

                  1.0 by graphical •
                  interpolation

                  0.056(0.032-0.100)

                  0.01: •  -••  -   >1,000

                           -    .            46(41-51)


                                            270(235-309)

                                            9(8-10).

                                     •      >1,000

                                            121(96-149):
Note:  Greater than (>) values-, are the result of confirmatory tests.
       Ranges (
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                                                      •  :,       •.r'r •)'-'''"•"'  .-"-I : -.r;.•"•". i'-"'—"^!''--"•'•'!"""Vv' 'X'''—'-•'.'"• • >:
       Appendix A.  Pesticide Sources, Purities, Major  Pests,  Applications,  and'Registration Status  >'•-/• ..•;?•'•'  •
CO
REGISTERED TRADENAMES , v
Parameter
Conmon Name
Technical
Material Source

Lot


Purity, %
Manufacturer
In-house
Date Received
Use
Major Target
Pests



Application


• -, .A


Status

Ambush3 .'i !
Permethrlri '• i
ICI
America's, 'Inc. •

47/82- • :-\ -.•••••
Si ;: .'.]!'•.!
" '.'',' ''

93
93
5/4/79
Insecticide •
budworm •
bollworm ..
bollweevil ;


Cotton '"•





Registered
(uses pending)

Bolero15
Thlobencarb
Chevron !
- Chemical Co\

1039T" ' • '•••- '



95.5Sr>
90
5/15/79 •'
Herbicide-
preemergent and
early postemer-
gent grasses and
broadleafs

Rice. ••-"•





Section 18
Emergency
Exemption
Buxc
Bufencarb
Chevron
Chemical Co.

Analytical
Standard
from RTP"

— * • '.-r
'.'.
":.
Insecticide
corn rootworm
rice water
weevil


Corn
R1ce '-' :

>-


Registered

Dursband
Chlorpyrlfos '\ .-
Dow ." .•:•-, •-•'''"
Chemical Co. ,' '..'

1-5503-2 :."'

* . ' -f - • •
- ''.-"'•• •
97.7 v.uv^'i
92 . ••' :.;•. ,-:l<
4/24/79 . .". .
Insecticide ' ;
fire ants •'•'. '. -.
household pests- •
worms ;
scale ; !
borers ,
soil '
turf .
foliage _; :.. '
cotton
corn
cattle
Registered
(uses pending) _.;
. i ";•:•. '"','••
Fentr1fan1le
PP 199
Fentrlfanil .
ICI
United States,
Inc.
Analytical
Standard ';
from RTP

- - ' . "
,; . .--• ••'• .'
... — '_ .
Insectlcde
mites
aphids
. scale Insects


apples
citrus

!'••'•


Experimental
- ' Use Permit
/ '- ••".' •' '
Larv1nf

Union ,
Carbide

511-01-2828 •



99 '
• —
6/7/79
Insecticide
• lepldopterous-
pests

I
•.;•'.
cotton !
' soybeans ;'
j



Experimental
Use Permit

Pydrln9
fenvalerate
Shell ,
Development
Co.
80115

.

—
100 '
4/20/79
Insecticide
budworms
bollworm
bollweevil


cotton
vegetables
fruit



. Registered
(uses pending)

       a  3-(phenoxyphenyl)  methyl (ฑ)-c1s, trans-3-(2,2-dichloroethenyl)-2,2-d1methyl cyclopropanecarboxylate
       (approx.  60%  trans,  40X c1s  Isomers)
       h^                                                     '.'••:             .-;••-',..,'•
       b  S-(4-chlorophenyl) methyl  dlefehylcarbamothloate                        '     '  >  .   ,'..';:


       c  mixture of  m-(ethylpropyl)  phenyl  methylcarbamate and m-(1-methylbuty1) phenyl irethylcarbamate  1n
       approx.  ratio of  1:3         I '       '


       d  0,0-diethyl  0-(3,5,6-tr1chloro-2-pyr1dyl)-phosphoroth1oate


       e  N-[2-chloro-5-(trifluoromethyl)  phenyl]-2,4-din1tro-6-(tr1fluoromethyl) benzenamlne           ':


       f  ethanimidotMoic add,  N.N1  -Cth1ob1s[(methyl-1m1no)carbonyloxy]]b1s-dimethylester            "   . '


         Jano  (3-phenoxyphenyl) methyl 4-chloro-alpha (1-methylethyl) ben^pacetate

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                             Appendix -B

          Composition  of  mixes  added to  algal  growth  media  2.
       \ -  -

     Nutrient Mixes                          Amount  per-liter
     Metal  Mix3
       FeCl3-6H20                              0.048g
       MnCl2'4H20                              O'.144g
      , ZnSO,'7H~0    .               -.     '     0.045g

               2
CuSO/,'5H90-                   '          0.157mg

               2
       CoCl2'6H20                   -           0.404mg
       H3B03              : .  ,    -           .  1.140g
       Na2EDTAd                       .         Ig
       Glass-distilled or deionized  water      lฃ

     Vitamin mix
       Thiamin hydrochloride                   50mg
 .  .    Biotin             .      ...    ".  .    O.Olmg
       B12                                     O.lOmg
       Glass-distilled or deionized  water    100mฃ

     Minor Salt Mixc
       •K3P04                                   3.0g   ;
       NaN03                                  50.Og
       Na2Si03'9H20                           20.Og
       Glass-distilled or deionized  water      U

3Add 15.0 nu/ฃ of test solution.
"Add  0.5 nu/ฃ of test solution.
cAdd  1.0 mi/a of test solution.
ฐEDTA added only to stock medium.

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TECHNICAL REPORT DATA
(Please read Instructions on the reverse before completing/
1. REPORT NO. 2.
EPA-600/4-81-076
4. TITLE AND SUBTITLE
Initial Toxicological Assessment of Ambush, Bolero, Bux,
Dursban, Fentrifanil, Larvin and Pydrin: Static Acute
Toxicity Tests with Selected Estuarine Aglae, Invertebra"
7. AUTHOR(S)
Borthwick, Patrick W. and Gerald E. Walsh
9. PERFORMING ORGANIZATION NAME AND ADDRESS
12. SPONSORING AGENCY NAME AND ADDRESS
Environmental Research Laboratory Pi
Office of Research and Development
Environmental Protection Agency
Gulf Breeze, Florida 32561
3. RECIPIENT'S ACCESSION NO.
5. REPORT DATE

6. PERFORMING ORGANIZATION CODE 1
;es, and Fish
8. PERFORMING ORGANIZATION REPORT NO.
10. PROGRAM ELEMENT NO.
ACBE1A
11. CONTRACT/GRANT NO.
In-house
13. TYPE OF REPORT AND PERIOD COVERED
•oblem Oriented Rebort5/79-8/81
14. SPONSORING AGENCY CODE
ORD-600
15. SUPPLEMENTARY NOTES
16. ABSTRACT
; Selected static toxicity tests were conducted -with /
Dursp'anฎ, Fentrifanilฎ, Larvinฎ,. and Pydrinฎ to determine
species representing four major phyla. Algal bioassays v
algae to determine the concentration of pesticide that we
growth by 50% in 96 h." "Static toxicity tests with molluj
concentration of pesticide that would cause 50% of the e>
abnormally in 48 h. Static acute lethality tests with cป
determined the concentration of: pesticide that is- lethal
organisms during a 96-h exposure.

\mbushฎ, Boleroฎ, Buxฎ, 	 -.— '•
2 the sensitivity of
vere conducted with marin'e"
Duld inhibit population
;k larvae estimated the
';('.' ' ' '; ' ' L. " -"• 0 •" -' "- f. /1 '; ..I. '
17.. .: ^,. ... , .., - .-• ,.\. .,"-," KEY WORDS AND DOCUMENT ANALYSIS
a. - -. .DESCRI.PTp.RS b.lDENTIFIERS/OPEN^ ENDED TERMS
.,,.,,..
.<.••".' '"hC '-. •'-.-' •' ~ '.'".'': : ' . L 5P'* '.'.'•"•',.. C .V: '•".'?"'.•'•• ". ' ('•',- . ;. . '-. ; .' '
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21. NO'. OF PAGES
9
22. PRICE
EPA.Form'2220-1 '(Rev. 4V*77)".  ;' P.kevibys  E'piT.iON.f.

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