United States       Prevention, Pesticides     EPA712-C-98-055
          Environmental Protection    and Toxic Substances     March 1998
          Agency        (7101)
&EPA   Spray Drift Test
          Spray Droplet Size

     This guideline is one  of a  series  of test  guidelines that have been
developed by the Office of Prevention, Pesticides and Toxic Substances,
United States Environmental  Protection Agency for use  in the testing of
pesticides and toxic substances, and the  development of test data that must
be submitted to the Agency  for review under Federal regulations.

     The Office of Prevention, Pesticides and Toxic Substances (OPPTS)
has  developed this guideline through  a process of harmonization that
blended the testing  guidance  and requirements that  existed in the Office
of Pollution Prevention and  Toxics  (OPPT) and appeared in Title  40,
Chapter I,  Subchapter R of the Code of Federal Regulations  (CFR),  the
Office of Pesticide Programs (OPP) which appeared in publications of the
National Technical  Information Service (NTIS) and the guidelines pub-
lished by the Organization  for Economic Cooperation and Development

     The purpose of harmonizing these  guidelines  into a single set of
OPPTS  guidelines is to minimize variations among the testing procedures
that must be performed to meet the data  requirements of the U. S. Environ-
mental Protection Agency  under the Toxic  Substances  Control Act  (15
U.S.C. 2601) and the Federal Insecticide, Fungicide and Rodenticide Act
(7U.S.C. I36,etseq.).

     Final  Guideline Release: This guideline  is available from the U.S.
Government Printing Office, Washington, DC 20402 on The Federal Bul-
letin  Board.   By  modem  dial   202-512-1387,  telnet   and   ftp:
fedbbs.access.gpo.gov  (IP, or  call 202-512-0132 for disks
or paper copies.  This  guideline is also available electronically in ASCII
and  PDF (portable document format) from the EPA's World  Wide Web
site  (http://www.epa.gov/epahome/research.htm) under the heading "Re-
searchers and Scientists/Test Methods and Guidelines/OPPTS Harmonized
Test Guidelines."

OPPTS 840.1100  Spray droplet size spectrum.
     (a) Scope—(1) Applicability. This guideline is intended to meet test-
ing  requirements  of both  the  Federal  Insecticide,  Fungicide,  and
Rodenticide Act (FIFRA)(7 U.S.C. 136, et seq.) and the Toxic Substances
Control Act(TSCA)(15 U.S.C. 2601).

     (2) Background. The source material used in  developing this har-
monized OPPTS test guideline is the OPP guideline  201-1—Droplet size
spectrum testing (Pesticide Assessment Guideline, Subdivision R: Pesticide
Spray Drift Evaluation, EPA Report 540/9-84-002, April 1984).

     (b) General—(1) Purpose.  Droplet size spectrum studies are per-
formed to determine the influence of a number of equipment and formula-
tion  parameters and initial environmental factors on the formation of the
droplets as they leave the pesticide dispersal equipment.  The  major param-
eters that will be tested are type of nozzle,  orientation to the wind shear,
and formulations. By studying this part of the application process in detail,
the more expensive field evaluations will have to be performed less fre-
quently. Droplet size studies indicate  which of the conventionally used
nozzle types, orifice sizes, operating conditions,  adjuvants,  formulations,
and discharge orientations would produce the greatest volume of droplets
less than 100 microns in diameter. Droplet  size  spectrum studies may  be
carried out in wind tunnels or during  the field  evaluation of drift using
commercial equipment.

     (2) Test standards. In  addition to  those test standards set forth in
OPPTS guideline 840.1000, the following standards apply:

     (i) Test substance. A formulated end-use product of the same formu-
lation category as the end-use product to be registered, i.e. wettable pow-
ders,  emulsifiable  concentrates,  etc., and use, i.e. herbicide,  insecticide,
etc.,  will be tested.

     (ii) Equipment.  The label-recommended or commonly-used nozzles
and  associated parts,  nozzle  pressures, and nozzle discharge orientation
that would produce droplets that would be most conducive  to spray drift
should be tested.

     (iii) Meteorological conditions. (A) For wind tunnel studies, the fol-
lowing conditions should be tested:

     (7) The product  should be tested at various temperature levels from
10 to 35 °C.

     (2) The air flow (velocity) in the wind tunnel may be  adjusted to
relate to the type of  equipment used (e.g.  130 to 225  kmph  (80 to 140
mph))  for fixed-winged aircraft and air carriers,  65  to  110  kmph (40 to
70 mph) for helicopter (rotary-winged aircraft),  and 5 to 40 kmph (3 to

25 mph) for ground applications (including sprinkler irrigation) other than
air carriers (mist blowers).

     (B) For  field determination studies,  the  meteorological  conditions
should be those most conducive to spray drift (relatively high temperature,
low relative humidity, and inversion). Field studies with the elevated tem-
peratures  are  conducted to determine the  effect  of  a  higher evaporation
rate on the droplets.

     (iv) Collection devices. The collection devices should be either laser
particle measuring systems, collection cards (both horizontal  or  vertical
surfaces), air samplers, or other devices by which droplet size distribution
can be determined.

     (c) Data reporting. The registrant's report on droplet size spectrum
studies  should include all information necessary to  provide: A complete
and accurate description of the treatments and procedures; sampling data;
data on storage of the samples until analysis (if performed); any chemical
analysis of the collection surfaces as to chemical content (if performed);
recovery  efficiency;  reporting of the data, rating system and statistical
analysis; and  quality control measures/precautions taken to ensure the fi-
delity of the operations. Specifically, each report should include  the fol-
lowing information:

     (1) General, (i)  Cooperator or researcher (name and address), test
location (county  and  state; country, if outside of the U.S.A.), and date
of study;

     (ii) Name (and signature), title, organization, address and telephone
number of persons responsible for planning/supervising/monitoring.

     (iii) Trial identification number.

     (iv) Quality  assurance indicating: control measures/precautions fol-
lowed to ensure the fidelity of the droplet size; record-keeping procedures
and availability of logbooks; skill of the  laboratory personnel;  equipment
status of the laboratory; degree of adherence to good laboratory practices;
and degree of adherence to good agricultural  practices for application of

     (v) Other information the registrant considers appropriate and relevant
to provide a complete and thorough  description of the test procedure and

     (2) Control  data. Control values for the test should be reported. Due
to the wide diversity of pesticide properties, use patterns, and organisms
exposed in the field environment, specific reporting requirements for con-
trol values (as to source,  sampling regime, and  total  number of sample
data submitted) will depend upon the complexity and variability of the
environment in which the test is to be conducted.

     (3) Test substance and physical properties, (i) Identification of the
pesticide  active  ingredient  including  chemical  name,  common name
(ANSI, BSI,  ISO,  WSSA),  and company developmental/experimental

     (ii) Active ingredient percentage by weight  in the formulated end-
use product used or substituted (with reasons for substitution  of end-use

     (iii)  Type of  formulation (e.g., emulsifiable concentrate,  flowable
powder, liquid, etc.). Product formulation used, diluent and manner of dilu-
tion, mixtures, adjuvants,  and their  physical properties  (surface tension,
viscosity,  density, vapor pressure, etc.).

     (iv) Dosage of active ingredients or acid equivalent per unit area of
land or gallons-per-minute (gpm) or liters-per-minute  (1pm).  The con-
centration of the final diluted spray mixture  (in  the spray tank) should
be sampled, chemically analyzed, and reported.

     (v) If droplet size distribution is determined during the field evalua-
tion, physical  property data,  including  droplet  size, viscosity, density,
vapor pressure, visco-elasticity, and surface tension, should be determined
and reported.

     (4) Test  method. Each report should contain a statement regarding
the method  of droplet testing used (wind tunnel, aircraft, mist blower) in-
cluding a full  description of the  experimental design and procedure.  In
lieu of the wind tunnel study required for this test,  droplet size distribution
may be determined under field conditions during the spray drift evaluation
test as provided in OPPTS 840.1200.

     (5) Collection surfaces, (i) Identification of the collection surfaces.
The  collection surfaces may  include laser particle measuring systems
(PMS), collection cards (flat horizontal  or vertical surfaces), air samplers
or other devices by which droplet size distribution can be measured;

     (ii) Identification of the number of replicates.

     (iii) Distance between nozzles and collection surface/detection device.

     (6) Site of the test, (i) Type of site  of the droplet size spectrum study
as to whether the study was performed in or out of a wind tunnel or in
the field during the drift field evaluation study.

     (ii) Climatological data (records of applicable conditions for the type
of site, i.e, temperature, air flow or velocity, wind direction [field study],
relative humidity).

     (7) Application equipment, (i) The nozzle type, orifice size, and core

     (ii) The nozzle pressure and flow rate.

     (iii) The nozzle discharge orientation to the airstream. Nozzle  dis-
charge orientation should be  designated in degrees related to the direction
of travel of the spray equipment. Zero degrees indicates a horizontal nozzle
discharge pointing rearward (opposite to the equipment direction of travel),
90* indicates a vertical nozzle discharge pointing  downward, and 180* in-
dicates a horizontal nozzle discharge pointing forward (with the equipment
direction of travel).

     (iv) The  estimated  minimum  and maximum nozzle-to-target height.

     (v) Air velocity past the nozzle.

     (vi) Descriptions of techniques and size determination devices.

     (vii) Particle size distribution vs. cumulative percent volume and  par-
ticle size distribution vs. droplet number (frequency) (an attempt should
be made to determine the droplet size distribution where droplet formation
is finalized).

     (8) Additional  information. If droplet size distribution is determined
during the  field evaluation, the following information should also be  sub-

     (i) A  diagram of the plot  indicating north, swath width, and orienta-
tion, and location and spacing of the collection stations.

     (ii) Temperature at two levels, wind velocity and direction, variations
in velocity and direction during the application, relative humidity, atmos-
pheric pressure, and air stability. The latter is expressed as Barad's stability

     SR =[(T3 meters - TI meters)/(ave. wind velocity)] x 105

Temperature should be determined just above the  canopy (Ti)  and at least
2 m above that (Ts) for all applications. A standard vertical separation
should be  2 m. Wind velocity should be determined at least 1 to 2 m
above the canopy height.

     (iii) Spray volume (liters  per hectare  or  gallons per  acre)  and
carrier(s).  The maximum and minimum  carrier volumes recommended on
the  label should be reported.

     (iv) The ground speed of application equipment, the number of swaths
sprayed during exposure  of collecting surfaces, and swath width.

     (v) The quantity of active ingredients(s) or acid equivalent collected
or  detected at each sampling point in terms  of kilograms per hectare
(pounds per acre).

     (9) Results, (i) The particle size distribution versus cumulative per-
cent volume and versus droplet number (frequency) should be reported.

     (ii) The 10th, 50th and 90th percentile  of the size  distributions with
respect to droplet volume and number and standard deviations,  where pos-
sible, should be reported.

     (d) In lieu of the wind tunnel study required by this section, droplet
size distribution may be determined under field conditions during the spray
drift evaluation test as provided in OPPTS 840.1200.