United States
      Protection
Office of Pesticide Programs
Washington, DC 20460
EPA 540/9-36-'31
June 19S6
Agenev
Hazard Evaluation Division
Standard Evaluation Procedure
Pesticide Spray Drift Evaluation:
Droplet Size Spectrum
Test and Drift Field Evaluation Test
                         Support Document 59

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                                    EPA 540/9-86-131
                                    June 1986
               HAZARD  EVAL-UATION DIVISION

             STANDARD  EVALUATION PROCEDURE

            PESTICIDE  SPRAY  DRIFT EVALUATION-:

DROPLET SIZE SPECTRUM  TEST AND DRIFT FIELD EVALUATION'TEST
                       Prepared  by

                  Robert  W.  Hoist,  Ph.D.
     Standard Evaluation Procedures  Project Manager
                   Stephen  L.  Johnson
               Hazard Evaluation Division
              Office of Pesticide Programs
     United States Environmental  Protection Agency
              Office of Pesticide Programs
                Washington,  D. C .   20460

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                          TABLE  OF  CONTENTS


                                                         Page

  I.   INTRODUCTION    '

       A.  Purpose of the Standard  Evaluation
           Procedure	    1
       B.  Background Information	    1
            1.  Droplet Size Spectrum Test	    1
            2.  Drift Field Evaluation Test	    1
       C.  Objective of the Pesticide Spray Drift
           Evaluations	,. . . .    2
            1.  Droplet Size Spectrum Test  	    2
            2.  -Drift Field Evaluation Test 	    2


 II.   INFORMATION TO BE SUPPLIED	    2


III.   DATA INTERPRETATION	 .    3


 iv.  'THE DATA EVALUATION PROCESS

       A.  Identify Data Gaps	   3
       B.  Assess the Appropriateness  and Adequacy
           of  the Data 	    4
       C.  Report Preparation	    4
       D.  Conclude if the Requested  Action is
           Supportable	    4


  V.   APPENDICES

       Appendix 1:   Information Requested of  the
                    Registrant		    5

       Appendix 2:   Specific Questions  for  the
                    Revi ewe r	    9

       Appendix 3:   Sample Standard Format  for
                    Preparation  of Scientific
                    Reviews		   13

  REFERE NCES	   14

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                   PESTICIDE SPRAY DRIFT  EVALUATION;

       DROPLET SIZE TEST SPECTRUM AND  DRIFT  FIELD  EVALUATION. TEST


  I.   INTRODUCTION

       A<   Purpose of the Standard Evaluation Procedure

       This Standard Evaluation Procedure is designed to aid  Exposure
  Assessment Branch (EAB) data reviewers  in  their  evaluations of  drop-
* let size  spectrum and pesticide drift field evaluation studies  sub-
  mitted by registrants in the assessment of pesticide exposure.

       B •   Background Information

       Droplet  size spectrum studies  and drift field evaluation stu-
  dies  are  designed to  provide  off-site transport data on a pesticide.
  These -off-site  transport  data are needed to. evaluate the effect of
 pesticide  exposure  to .humans,  plants, fish  and wildlife by  products
 ?n?fn£?d  t? ^  applied  by ^rial, air carrier, mist blower, overhead
 sprinkler  irrigation and  other  outdoor application equipment.  These
 studies are_ required  by 40 CFR §  158.142 to support the registration
 of any pesticide  intended for  outdoor use  under the Federal Insecti-
 cide, Fungicide  and Rodent icide Act  (FIFRA),  as amended.

       Pesticides  with outdoor use patterns where aerial  transport of
 the pesticide to  off-site locations  is not  likely to occur d™ not have
 caMon     Tf ^H-   ^ USS Patterns  include  ground-hydraulic appli*
 cations.    If this or other use  patterns  do  readily expose non-taraet
 ofTnnr^0^1^1"9 hUmnS  t0' the Pesticide through  aerial  transit
 of droplets, the- pesticide  drift potential  may  need  to  be evaluated.

           !•  Droplet Size  Spectrum Test

the  in$?,,*™le* 'SiZS spectrum  studies are  performed to determine
 an!  ini^Ti      a nUmber, °f equipment and  formulation  parameters
 and  initial environmental  factors on  the formation of the  droplets
™t™^r*-i^eHPeSticide diSPersal equipment.  The major para-
meters  that will be tested are type of nozzle, orientation  to  the
wind shear- and  formulations.   By studying this part of the applic
have" ?o°hTS ^ ^t'  the m°re ^pensive field evaluations^! 1
have to  be  performed  less  frequently.
           2-   Drift  Field Evaluation Test
t-ho  -                 evaluation studies are performed to determine
the  influence  of  a  number of equipment and formulation parameters

    e0
ciderom^  aaC.°rS  °n  the  disPersal °f the formulatepest i -
cide from the application  equipment to the intended surface(s).  The
        tnwnd   h                            s) of nozzl   orienta-
rative favors         '  forTOulations'  cross-wind velocity . and evapo-

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       C.  Objective  of  the Pesticide Spray Drift Evaluations

       The objective  of  the pesticide spray drift evaluat-ions is' to
 determine  if  a  pesticide formulation applied as directed has the
 potential  to  be  transported to off-site,  non-target areas and thereby
 cause -'detrimental effects on non-target plants, animals and humans.
 The  extent  of possible  detrimental effects on plants, animals and
 humans will be  determined by various scientists evaluating phytotox-
 icity, fish,  wildlife  and insect toxicity, and human and domestic
 animal toxicity.  These tests are required by 40 CFR § 158 and the
 Pesticide Assessment Guidelines, Subdivisions E, F, J and L:  Hazard
 Evaluation.:'"~~

            1.  Droplet  Size Spectrum Test

      The droplet size  spectrum test provides information on the
 effects of  pesticide application equipment and formulations on drop-
 let  sizes which  in  turn influence the  extent of pesticide droplets
 being carried by air currents to non-target areas.   Quantification
 of the pesticide movement by air currents is evaluated in the suc-
 ceeding study' on pesticide drift field evaluation.

           2.  Drift Field Evaluation Test

      The drift field evaluation test provides information on the
 effects of the environment and application equipment on the extent.
 of off-site, off-target transport of pesticides by  air currents
 immediately following release from application equipment.   The ex-
 tent and quantity of drift will be determined in order that it can
 be compared to toxicological study information for  possible effects
 on non-target plants, wildlife  and humans.   It is important to note
 that it is not the purpose of the drift field evaluation study to
 evaluate the extent of  aerial movement of  a pesticide as a result
 of evaporation of the material  from plant,  soil or  other substrate
 surfaces after deposition.


II.  INFORMATION TO BE SUPPLIED

      The registrant's reports on droplet  size spectrum and drift
 field evaluation studies  should include all  information necessary
 to provide:  1)  a complete and  accurate description of  the treat-
 ments and-procedures, 2)  sampling'data, 3)  data on  storage of  the
 samples until  analysis,  if  so performed,  4)  any chemical  analysis
 of the collection surfaces  as to chemical  content,  if  so performed,
 5) recovery efficiency,  6)  reporting of the  data, rating  system and
 statistical analysis, and  7)  quality control  measures/precautions
 taken to ensure the fidelity  of  the  operations.

      A guideline of  specific  information  that should be  included" in
 the registrant's report on  droplet  size spectrum and drift field
 evaluation  studies  is provided  in  Appendix  1  of  this document.'

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                                  -3-
  This list of requested information and reviewer aids  is  derived  from
  the Pesticide Assessment Guidelines, Subdivision  R;   Pesticide  Spray
  Drift Evaluation, which is complemented  by this Standard Evaluation
  Procedure.


III.   DATA INTERPRETATION

       The acceptability of the study results will  depend  upon whether
  the test requirements/standards are followed.   If  a  deviation  is
  made, a determination must be made as to whether the  deviation has
  changed the quality of th_e_results in such a manner  that the results
  cannot be extrapolated to the natural environment.   There should  be
  little or no deviation from the liberalized standards prescribed
  in  this study.  -                     -  • •

       The results of the droplet spectrum study  for the chemical
  formulation with respect to the quantity of pesticide applied and
  nozzles used are important.  The concentration  of  the chemical  in
  the carrier is  important in that varying concentrations  can lead  to
  large variations in droplet size spectrums.  The  results of the
  drift field evaluation study for the chemical formulation with
  respect to the quantity of pesticide applied and  nozzles used are
  also important.   This will help quantify the pesticide off-target
  movement due to equipment and environmental conditions and enable
  the Agency to prepare exposure assessments for the chemcial and that
  use pattern.

       There is no decision point for the droplet size  spectrum with
  respect to performing the drift field evaluation study.   There is
  also no decision point for the drift field evaluation study with
  respect to performing additional studies.


 IV.   THE DATA EVALUATION PROCESS

       Upon careful examination of the information/data supplied by
  the registrant  in his  submission to the Agency, the reviewer shall
  evaluate the data as follows.

       A.  'Identify Data Gaps

       Using Appendix 1 of this document as a guide, the reviewer
  should  look for  data gaps - omissions  in the  information  supplied
  by  the registrant in his report.  These should be duly noted in the
  reviewer's  report and  a judgment made  as to which are considered
  significant enough to adversely affect the review process.  Those
  so  identified should be communicated  back to  the registrant by the
  Product Manager  for corrective action.

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                                  -4-
      B>  Assess the Appropriateness  and Adequacy  of  the Data

      The data reviewer then considers  the  appropriateness,  i.e.,
 the intended use pattern, and adequacy of  the  data/information that
 has- been supplied.  Appendix 1 of this document is a  useful  guide
 to the various parameters that need  to be  considered.   Appendix 2
 provides specific questions that should be answered by'the 'reviewer'
 during the study evaluation process.  Statistical treatments of the
 data should be independently verified and  the  quality  control ore-
 cautions noted.   •                               ,

      As an adjunct to these, the reviewer  should-draw  upon the tech-
 nical guidance in the reviewer aids materials  that are  available.
 (See also the recommmended references in Subdivision R  - Pesticide
 Spray Drift Evaluation.)   A listing of additional source materials
 is located in the References section of this document.

      In addition to the  data gaps noted above, any perceived  defici-
 encies  in the data/information supplied should also be  identified
 A  statement as to these  deficiencies should be made in  the reviewer's
 report  and corrective  action to resolve them should be  provided
 This  information can be  relayed to the registrant by the Product
 Manager for appropriate  action.  •

      C.   Report  Preparation

      The  Agency  reviewer  prepares  a  standard  review report followino
 the standard  format  for preparation  of scientific  reviews as provided
 in Appendix 3  of  this  document.  All  important information provided
 by the  registrant  including  the methodology and results is to be
 summarized  in  order  that  future evaluations can be made.  The results
 may be  expressed  in  the form of tables where  specific  values  are
 rela.ted.  t igures  (graphs) may be provided  but are not to be  the sole
 source  of  the  values needed  for future evaluations.

     D'  Conclude  if the  Requested Action is  Supportable

     Lastly, the reviewer considers the results of  the  droplet size
whhrUm^hr      Sld evaluation studies and makes  a judgment  as to
whether they support the  requested registration action  of  the data
               ^ Kata arS ^ s^P°rtive, possible alternativf  '
               maY  6/^en. ^ the registrant,  such as  label  modifi-
  tte  d     ^9gested-  If Deficiencies /omissions exist in  the sub-
mitted data, the reviewer may have to  defer judgment until such time
as  appropriate corrective action has been rendered by  the  registrant

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                                  -5-
                               APPENDIX 1

                INFORMATION REQUESTED OF THE REGISTRANT


       The registrant's  report  on  droplet  size spectrum and drift
 field evaluation studies  should  include  all information necessary
 to provide:   1)  a complete  and accurate  description of the treat-
 ments and procedures,  2)  sampling data,  3) data on storage of the
 samples until  analysis, if  so performed,  4) any chemical analysis
 of the collection surfaces  as to chemical content,  if so, performed ,
 5) recovery efficiency, 6)  reporting  of  the data,  rating system and
 statistical, analysis,  and 7)  quality  control measures/precautions
 taken  to ensure  the fidelity  of  the operations.

       Specifically, each report should include  the  following informa
 1 1 o n •                                                     "-


 I.  General

       °  Cooperator or  researcher  (name and  address),  test location
 (county and state; country,  if outside of the  U.S.A.), and  date  of
 s t UQ y j


                             ' title, organization,  address  and
                                  ) ***V°™^*  «« Panning/super-

      0  Trial  identification number;
                 assurance indicating:  control measures/precautions
  Mdd          re ^ fidelifcy of the droplet size and/or drift
 innhonv!    ^^   ?nS:  reC°rd-keeping Procedures and availability of
 logbooks;  skill  of the laboratory personnel; equipment status of
       °rator           of  adherence to good laboratory practices;
                         ^ fl°°d ^'^tu.al practices for applica-
      °  Other  information the registrant considers appropriate and
          °                                              S«  t'lf.*
    Test Substance  (Pesticide)
     » ' Identification of  the test  pesticide  active  ingredient (ai)
including chemical name, common name  (ANSI, BSI,  ISO,  WS!A" and
Company developmental/experimental  name;               ****)-,  and

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                                   -6-
           ctivVngrdient percentage by weight in the  formulated

                       °r Subst^uted  (with, reasons for  substitution
  able  powdr l^uSi^e?"?? (e*g" «BUl8i.fl«"e concentrate, flow-





  land  or  fnSe,iriate(S)  ln termS  °f acti.ve ingredient per unit area of
,  land  or  in  gal Ions -per -minute  (gpm)  (liters-per-minut e  [1pm]); and



     .-A.   Droplet  Size  Spectrum Tests



 hlnwJi  Method of droplet  testing (wind tunnel,  aircraft, mist
 UJ. Omr L ) •



       B-   Drift Field Evaluation  Tests



          Identification  of  the  use  of dyes or  other  indicators; -an d



 cides.°   Identification  of  adjuvants  used, and  other  tank  mixed  pesti-






 IIZ-  Collection Surfaces



      A-  Droplet Size Spectrum Tests




      0  Identification of  the collection surfaces.  The  collect ion








        Identification of the number of replicates; and



device. °iStanCe  between nozzles and collection surface/detection




     B*   Drift  Field Evaluation Tests
        Identification of  the  number  of  replicates;  and

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 IV.  Site  of  the  Test


       A.   Droplet 'Size  Spectrum Tests


  ^   ! ^TYPe  °f  SitS °f  the  dr°Plet size  spectrum study as to whether

  durin^T^/?^  *" ^  '°Ut  °f  *  "^
  during the drift field evaluation  study;  and
          Climatological data  (records of applicable conditions  for  the
                                     ^ flow  or  velocity-  wind  d
       B.  Drift Field Evaluation Tests


       0  Location of the test site;
  of  fo..ed                        6   ™™ ^ «  type
tvoe of                data  (records  of  applicable  conditions  for the
type of site, i.e., temperature, thermoperiod, rainfall or' water! nn

reP 0t°Peri0d' alr V6lOCit  a                            "
                           V6lOCity and Wnd Direction  retve


       °-  Field lay-out (graphic display is encouraged).

 V.  Application  Equipment


          Nozzle type,  orifice  size,  and core identification;


 and   °   N°22le Pressure'  flow «te' and orientation  to  the  airstream;



       °   For drift field evaluation  tests,  identification of i-h^
VI.  Results


      A* - P^oplet Size Spectrum Tests
      B-   Drift Field Evaluation Tests

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                                  -8-
VI I.  Evaluation

       A.  Droplet Size Spectrum Tests

       0  The 10th, 50th and 90th percentile of the size distributions
  with respect to droplet volume and number and standard deviations,
  where possible.

       B.  Drift Field Evaluation Tests

       0  .The overall movement of the pesticide formulation as a result
  of aerial transport.

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                                  -9-  ,



                              APPENDIX  2

                 SPECIFIC QUESTIONS FOR THE  REVIEWER


      The following questions are  provided to aid the  reviewer  in
 performing the standard evaluation procedure  in  a  scientific manner
 and to complete a scientific review.


 I.  General                                     •

 -..- —  o  were the name of the cooperator  or  researcher (name  and
 address)/ test location  (county and state;  country, if  outside of
 the U.S.A.),.and date of study provided?

      0  Were the name (and s ignature ), title, organization, address,
 and telephone number of the person(s)  responsible  for planning/super-
 vising/monitoring and, for small  field plot studies,  applying  the
 pesticide provided?

      0  Was the trial identification number provided?

      0  Were quality assurance control measures/precautions  indicated?


II. . Test-Chemical
      0  Was the test.chemical being used  the  proposed  formulated
 end-use product or of the same formulation category as the end-use
 product to be registered?

      0  Was the active ingredient percentage  or  degree of purity  of
 the chemical given?

      0  Was the application rate given  in quantity per unit  area  (of
 plant or land surface) or in quantity per minute  (galIons-per-minute
 or li ters-per-minute) ?

      0  Was the application rate the maximum  label-recommended  rate?

      0  Were the physical properties of the total formulation given
 including surface tension, viscosity, density and vapor  pressure?

      A.  Droplet Size Spectrum Tests

      0  Were diluents and extent of dilution  identified  along with
 possible adjuvants, tank mixtures with other pesticides?

      .B.  Drift Field Evaluation Tests

      0  Were diluents or carriers, and the extent of dilution identi-
 fied along with possible adjuvants, tank mixtures with other pesti-
 cides, and tota.l spray volume?

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                                   -10-
          Were tank mixes evaluated,  i.f  so  specified,  for the intended
  use pattern that was being evaluated?

       0  Were controls used to note  any  possible  decay  or other loss
  of pesticide during the collection, transport, storage ajid  analysis?


III.  Collection Surfaces

       A.   Droplet Size Spectrum Tests

       0  Were tne collection surfaces or devices  identified  along
  with the equipment limitations?  Equipment "limitations  include the
  resolution of  tne microscopes, particle measuring systems,  or  air
  samplers,  and  the spread factor of  the droplets  on the  various
  collection surfaces (cards).,

       0  Were at least three replicates, of each test produced or
  were multiple  samples taken from only one replicate, i.e.,  were
  several  different sets of  nozzles of the same type tested?

       B.  Drift  Field  Evaluation Tests

          Were at least two  replicates of each sample position produced
  or were  multiple samples taken from only one replicate?

          Were the distribution  of  the collection surfaces of suffi-
  cient  number to establish  a definitive uninterrupted picture of
  deposits across the treated swath as well as outside the target
  area?

          Did  the collection pattern extend 1000 feet downwind for
  aerial and air  carrier  applications and 500  feet  for other  ground
  applications?

       0   Were the  collection surfaces placed  at the soil surface or
  at  the height of  the  surrounding  canopy?

          Were air  samplers  employed,  and  if so,  were they at least
  three downwind  locations (one  preferrably at the  farthest downwind
  site)?


IV.  Test Procedures

      A. Droplet Size Spectrum  Tests

         Was  the test site  specified-, i.e., wind tunnel, or field
 evaluation?

         Were the environmental conditions  that prevailed during the
 test (temperature, relative humidity, air  velocity) .provided?

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                                  -11-
       0   Were the environmental conditions/ especially wind velocity,
 steady  throughout  the  evaluation?

       B.   Drift Field  Evaluation Tests

       0   Was  the  test  site  specif ied,- i .e. , open field, cropped field,
 forest,  grove,.etc.?                 .

       0   Were the environmental conditions  that prevailed during the
 test'  (temperature  at  two levels, relative  humidity,  air velocity
 and direction,  rainfall  or .watering regime [overhead irrigation
 systems])  provided?'                                     '

      . °   Were the environmental condi-tions  that prevailed during at
 least one  field  test those conducive  to  the extensive drift of the
 pesticides?  .

       0   Were the environmental conditions,  especially wind velocity,
 steady throughout  the  evaluation?


 V.  Application  Equipment

       0   Were the nozzles those most likely to be used for the appli-
 cation of  that pesticide or the  intended use  pattern?

       0   Were the nozzle pressure, flow rate and orientation to the
 airstream  given?

      A.  Droplet Size  Spectrum Tests

       0   Were  the nozzles tested  the same as those  most  likely to be
 used  in  the  application of that pesticide?

      B.  Drift Field Evaluation  Tests

       0   Was  at least one test  run performed with nozzles and  other
 equipment configurations that  would result  in  conditionk conducive
 to the extensive drift of  the  pesticides?

      •°"   Was  the  speed of the equipment over the  ground  given?

       0  Was  the  estimated minimum and  maximum  nozzle-to^target
 height provided?                                        i


VI.  Reporting

      A.   Droplet Size Spectrum Tests

         Were  the particle size distribution versus cumulative percent
 volume and versus droplet number  (frequency) given?

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                                  -12-
       B.  Drift Field Evaluation Tests

       0  Were the particle size distribution versus cumulative  percent
  volume given and versus droplet number  (frequency) given  if the drop-
  let size spectrum study was performed.as part of  the  field  evaluation?

       0  Was a diagram of the plot or area provided indicating  north,
  swath width, and orientation, prevailing wind direction,  and location
  of the collection stations?

       0  Was the Barad stability ratio calculated?

       0  Were the quantities of pesticide at each collection station1
  and quantity of pesticide per area (g/ha) given?


VII.  Evaluation
       A.  Droplet Size Spectrum Tests                           '    -

       0  Were the results tabulated to indicate a luth,  5Uth and  90th
  percentile of particle size distribution with respect to droplet
  volume and number?          s

       B.  Drift Field Evaluation Tests

       0  Was the extent of downwind spray drift evaluated with respect
  to possible exposure to the non-target organism(s) that may be
  detrimentally affected?

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                                  -13-
                              APPENDIX  3

     SAMPLE STANDARD FORMAT FOR PREPARATION  OF  SCIENTIFIC • REVIEWS


      The following format shall be used in  documenting the  review
 of the Subdivision R:  Pesticide Spray Drift Evaluation  - Droplet
 Size Spectrum and Drift Field Evaluation Studies.


 Chemical:     (Common Name)

 Formulation:  (Percent Active Ingredient and Formulation  Type)

. Study/Action: -(Purpose of the Submission)

 Study Identification:

               (Subdivision R Test Title)
               (Reference or Registrant Data Information with
                Study Number)
               (EPA Accession Number)

 Reviewer:     (Name and Address of Reviewer; Date of Review)

 Approval:     (Quality Control Reviewer)

 Conclusions:  (Summary and Conclusion of Tests)

 Acceptability and Recommendations:

               (Decide as to (1) the scientific validity of  the
               study,  (2) compliance to the Subdivision R  -  Droplet
               Size Spectrum Test or Drift Field Evaluation  Test
               guideline, (3) data gaps, and (4) additional  infor-
               mation required by Agency.)

 Background:    (Introductory Information and Directions for  Use)

 Discussion:    1.  Study Identification
               2.  Materials  and Metho'ds
               3.  Reported Results
               4.  Reported Conclusions
               5.  Reviewer's Interpretation of Results and Conclusion

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                                  -14-
                              REFERENCES


 Akesson,  N.  B., W.  E.  Yates.  1984.  "Predicting  and  controlling
      flagged and extended aircraft swaths."  Ame r. Soc. Agric.  Engin.
      Paper No.  ASAE-AA-84-003

 Amberg, A. A.,  B. J.  Butler.  1970..  "High-speed  photography  as
      a tool  for spray-droplet analysis."  Trans.  ASAE 13:541-546

 Bache, D.  H.  1975.   "Transport of Aerial Spray III.  Influence of
      microclimate on  crop spraying."  Agric. Meteor.  15:379-383.

 Bode,  L.  E., B. J.  Butler.  1981.  "The three D's of  droplet
      size:   diameter,  drift, and deposit."  Aner.  Soc. Agric. Engin.
      Paper No.  AA-81-004

 Draper, W.  M.,  R. D.  Gibson, J.  C. Street.  1981.   "Drift  from  and
      transport  subsequent to a commercial, aerial  application of
      carbofuran: An  estimation of potential human exposure."   Bull.
      Environ. Contam.  Toxicol.  26:537-543.

 Goering,  C.  E., D.  B.  Smith.  1978.  "Equation for droplet  size
      distributions  in  sprays."  Trans.  ASAE 21:209-216.

 Haq,  K.,  N.  B.  Akesson,  W. E.  Yates.  1983.   "Analysis of droplet
     spectra and spray recovery  as a function  of atomizer type and
      fluid physical properties."  pp. 67-82 i_n T.  M. Kaneko and
      N. B. Akesson  (eds.)   Pesticide Formulations  and Application
      Systems:   Third Symposium.   ASTM STP 828.   Philadelphia, PA.

 Himel, C. M. , .S.  Uk.   1975.   "The biological optimum spray droplet
      size."  Proc.  5th Internat. Agric.  Aviation Conf.

 Hoist, R. W.  1983.  "Spray drift exposure assessment."   pp. 83-91
      in T'. M. Kaneko and N.  B. Akesson  (eds. )   Pesticide Formulations
     and Application Systems;  Third Symposium.  ASTM STP 828.
      Philadelphia, PA.

 Kautz, J., R. B.  Ekbald.   1984.   Analysis of Spray Deposit Cards
     Sensitive  to Non-Dyed Mixes.   Missoula, MT:   U.S. Forest
     Service, Equipment  Development Center.

 Matthews, G. A.   1979.   Pesticide Application  Methods.  London:
      Longman Publ.

Miller, C. 0.   1980.   "A mathematical model  of  aerial deposition of  •
     pesticides  from aircraft."   Environ.  Sci.  & Technol.  14:824-831.

 Reichard, D. L. ,  H.. J. Retzer, L.  A.  Liljedahl,  F. R.  Hall.  1977.
     "Spray droplet size  distributions delivered by  air  blast orchard
     sprayers."   Trans.  ASAE 20:232-242.

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                                -15-
                       REFERENCES (Cont i nue d)


Yates, W. E., N. B. Akesson, D. Bayer.  1976.  "Effects of spray ad-
     juvants on drift hazards."  Trans. ASAE 19:41-46.

Yates, W. E., R. E. Cowden, and N. B, Akesson.  1981.  "Effect of
     nozzle design on uniformity of droplet size from agricultural
    ' aircraft."  Amer, Soc. Agric. Engin. Paper No. AA-81-002.

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