ENVIRONMENTAL PROTECTION AGENCY
OFFICE OF ENFORCEMENT
EPA-330 2-77-018
PESTICIDE USE OBSERVATIONS
MONTEREY COUNTY, CALIFORNIA
(April 29-May 2. 1977)
NATIONAL ENFORCEMENT INVESTIGATIONS CENTER
DENVER.COLORADO
August 1977
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Environmental Protection Agency
Office of Enforcement
EPA-330/2-77-018
PESTICIDE USE OBSERVATIONS
MONTEREY COUNTY, CALIFORNIA
(April 29-May 2, 1977)
August 1977
National Enforcement Investigations Center
Denver, Colorado
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CONTENTS
I INTRODUCTION 1
II SUMMARY AND CONCLUSIONS 3
General Conclusions 3
Specific Conclusions 3
III BACKGROUND 6
IV DESCRIPTION OF STUDY AREA 9
V USE OBSERVATIONS 14
Pre-Application 14
First Application 21
Second Application 25
Post-Application 26
Cleanup and Disposal 30
VI EVALUATION OF METHODS 33
Spray Droplet Cards 33
High-Volume Sampling Devices 33
Environmental Sampling 34
Observation and Photographs 34
Pesticide Efficacy 34
REFERENCES 35
APPENDIX
Description of Sampling Devices and Methods
TABLES
1 Sampling Stations and Devices 12
2 Pesticide Residue Analyses (Phosdrin) . . 28
FIGURES
1 Monterey County, California 7
2 Station Locations 10
3 Additional Station Locations 11
4 EPA Weather Monitoring Station 13
5 Pesticide Storage Facilities 16
6 Temporary Storage Facility for
Used Pesticide Containers 18
7 Mixing and Loading 20
8 Platform containing spray droplet cards;
high-volume air sampling device .... 22
9 Protected Worker 22
10 Bell Helicopter Equipped with Spray Boom . 24
11 Aerial Pesticide Application at the
1.2-meter Height Level 24
12 Sanitary Landfill, Monterey County .... 32
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I. INTRODUCTION
Modern agriculture has become increasingly dependent upon the use
of chemical pesticides to increase crop production. As part of an
ongoing National Pesticide Use Observation Program to assess hazards
associated with pesticide use, the Environmental Protection Agency (EPA)
has performed monitoring activities in several parts of the country.
Monterey County, near Salinas, California, was selected to represent a
major food crop production area. An 11 ha (27 acre) field containing
mixed lettuce was selected by EPA personnel in conjunction with State and
local officials because of its close proximity to schools and residential
areas and the high potential for environmental degradation.
The primary objectives of the investigation were to:
1. Determine whether field applications of pesticides are
consistent with label requirements and appropriate regula-
tions.
2. Develop, modify and refine methods and technology by which
the potential environmental hazards associated with the
proper application of pesticides can be assessed.
3. Determine the extent and effect of pesticide drift from
target areas onto nontarget areas.
4. Document the efficiency of a closed-system pesticide transfer
operation.
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A four-day pesticide use observation began April 29, 1977. A
mixture of two pesticides, Phosdrin* and Dipel,* plus the "sticker-
spreader" Nu-Film-P* was applied by helicopter to the lettuce field on
May 2, 1977.
Emphasis of the study was to observe the application of Phosdrin, a
Class I pesticide under the Federal Insecticide, Fungicide and Roden-
ticide Act (FIFRA). Dipel, which is a biological insecticide, contains
the active ingredient Bacillus thuringiensis, Berliner and is categorized
Class IV under FIFRA regulations. Dipel is exempt from tolerance
requirements when applied to crops listed on the label according to
directions for use. Nu-Film-P causes the pesticide to adhere to foliage
and reduce erosion of spray residue by rainfall or overhead irrigation.
The study included sampling of-ambient air, water, and soils in the
field being treated with pesticides and in surrounding areas. Storage,
handling, mixing and application of the pesticide were observed. Weather
conditions were monitored during and after the pesticide application.
Various types of spray droplet cards, placed both vertically and horizon-
tally, and high-volume air sampling devices were used to characterize
spray drift.
Trademark^ see page 14.
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II. SUMMARY AND CONCLUSIONS
From April 29 to May 2, 1977, a pesticide use observation was
conducted by the National Enforcement Investigations Center (NEIC) on
a lettuce field in Monterey County, California. During the observation,
an EPA study team evaluated the activities associated with the aerial
application of Phosdrin to control an infestation of aphids.
GENERAL CONCLUSIONS
The use observation study in Monterey County revealed exemplary
storage and handling procedures.
The pesticide use was consistent with label instructions; however,
the close proximity of sensitive areas (an elementary school yard and
farm labor residences) created a potential health hazard.
The study indicated a need for the EPA, state and local officials
to initiate measures to protect humans and beneficial animals in areas
near spraying operations. Measures should include, but not be limited
to, regulating activities more closely during and after pesticide applica-
tion and establishing regulations which restrict access to pesticide
application areas. Currently, the State of California has a permit
system in effect in which all of the above issues should be addressed.1
SPECIFIC CONCLUSIONS
1. During pesticide application, potential human health hazards
were observed. An elementary school yard adjacent to the
target field contained numerous children; nearby residents
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4
were not notified during spraying operations; and farm roads
bordering the target field were not posted during spraying.
Pesticide drift was observed to occur in both the school yard
and the residential area.
2. Analyses of two soil samples and one water sample collected
from the school yard and the farm labor residence areas
revealed measurable amounts (0.02 to 0.03 yg/g and 0.9 yg/1,
respectively) of Phosdrin. Analyses of spray indicator cards
and high-volume sampling devices placed in these areas showed
Phosdrin contamination. The contamination of the areas was
directly attributable to spray drift. Phosdrin levels detected
in these areas were lower than acceptable tolerance limits
2
on lettuce eaten raw;2 (0.5 mg/kg) or 0.1 mg/m in air in
working environments3 (8-hr/day, 40-hr/wk occupational
exposure).
3. During and following the application, 8.0 yg of Phosdrin was
detected in a high-volume air sampler placed on top of the
Alisal High School, approximately 1.2 km (0.7 mi) north of the
target field; 6.5 pg of the pesticide was detected near the
mixing and loading site approximately 0.5 km (0.3 mi) south-
west of the target field. However, these residues could not
be attributed directly to the observed application.
4. Officials at the elementary school reported no increase in
absenteeism or illnesses, indicating that the observed
application had no discernible acute impact upon the health
of the school children.
5. The use of the closed system of pesticide transfer incorporated
features that are beneficial for the protection of worker safety.
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The system also reduces the number of necessary health
examinations because workers have less exposure to toxic
chemicals.
6. Observations and interviews by EPA personnel indicated that
the applicator was conscientious and well informed of the
proper use of pesticides. The aircraft pilot exercised good
judgement and used great care to minimize drift by attempting
to spray farther away from the sensitive areas than other
borders of the field.
7. The pest management program performed by the pest-control
adviser during this application was reported to be successful.
Crop damage by the aphid .infestation was minimal. Application
rates were less than the maximum concentration allowed by the
label which was both economically and environmentally beneficial
8. During this study the use of spray indicator cards to charac-
terize pesticide drift potential was not successful. Heavy
dewfall before and during the application caused the cards to
become saturated with moisture which obliterated droplet
impressions.
9. Pesticide residue analyses of Thermofax paper proved useful
during this study. However, because of the moisture on the
paper, values reported are considered to be conservatively
low.
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III. BACKGROUND
Monterey County lies along the coast of central California [Fig-
ure 1] encompassing more than 8,600 km? (3,300 mi?). In 1976, Monterey
County's gross farm income totaled more than $453 million. It ranks
among the top ten counties in gross farm income in California and among
the top twenty in the United States.
The 137 km (85 mi) long Salinas Valley comprises most of the
agricultural area in Monterey County. Rich soils, plentiful and high-
quality irrigation water obtained from underground percolating streams,
an average yearly rainfall of 36 cm (14 in), and a long and favorable
growing season help to make the Salinas Valley one of the richest
agricultural areas in the world. Crop production is extremely diverse
in Monterey County. Fresh vegetables are the major agricultural
commodity. Other crops include fruits, grapes, nuts, field crops such
as sugar beets and grains, seed crops and cut flowers. The largest
commercial crop in the county is lettuce, comprising more than $155
million of $311 million receipted for vegetable crops in 1976. Salinas
Valley is often referred to as the "Salad Bowl" of the nation.
During any month of the year, planting, cultivating and harvesting
may be observed. Extensive use of crop rotation is practiced so that
during any two-year period most cultivated land will produce a series
of three different food crops. Additionally, cover crops are planted
to preserve soil conditions prior to planting of commercial crops. As
in most highly developed agricultural areas, pesticide use is greatly
relied upon to insure maximum production from the land.
Lettuce was chosen as the target crop to be studied during this
investigation. Various insect pest infestations may occur from the
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SALINAS
Res.
SAN LOUIS OBISPO CO.
Figure 1. Wiontc-roy County, California
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time of planting until harvest. After an insect infestation has been
identified, spraying with insecticides will be initiated and repeated as
necessary until a few days prior to harvest.
Most owners of large farms in the Salinas Valley utilize the
services of licensed agricultural pest-control advisers. The pest-
control adviser has complete responsibility for identifying insect
infestations, making arrangements for application, selecting the proper
pesticide and indicating the rate of application. In other cases, the
adviser merely identifies insect populations and recommends a pesticide
application. The landowner must then make arrangements for the purchase
and application of the pesticide.
Monterey County averages between 30,000 and 40,000 individual
applications annually. Because of this high intensity spraying through-
out the valley, landing strips are strategically located in areas of the
most intensive spraying. Mixing and loading operations are performed
with use of large-capacity mobile nurse rigs. The nurse rigs rendezvous
with the aircraft at a landing strip near the target field. Dilution
water, pesticides and other materials are carried aboard the nurse rigs
which are capable of performing complete mixing and loading operations.
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IV. DESCRIPTION OF STUDY AREA
The site selected for pesticide use observations was an 11 ha
(27 acre) rectangular field planted with mixed lettuce. The field
was bordered by an elementary school and playground, farm labor resi-
dences, a public highway and other fields containing lettuce, cabbage
and fallow ground. Located within a 3 km (2 mi) radius of the lettuce
field site is a public high school, ranch buildings (containing
offices and ranch equipment), the Salinas Municipal Airport and a
residential portion of the City of Salinas, California. Farm roads
are located throughout the area to provide access of vehicles and
equipment to the fields for irrigation, cultivation, and harvesting.
4
Fifty-one stations were established in the study area [Figures 2,
3, Table 1]. Two stations (25 and 32) were on the target field. The
remaining 49 stations were off the field in areas where excessive drift
would be of concern, including the elementary school and playground,
the high school, local residences, the airport, and ponds located in
the area. Samples were collected from all stations except 29 and 50
which were established during the reconnaissance but later eliminated.
Indicator cards at station 30 were destroyed by school children playing
inside the playground.
The NEIC weather station was at the southwestern corner of the
target field near station 38 [Figures 2 & 4]. Wind directions, wind
velocities and air temperature, at 2m (8 ft) and 10m (32 ft) heights
to determine lapse rates, were monitored.
Honeybees were to be held in cages near the treated field in an
attempt to monitor effects of pesticide drift beyond the target area.
Excessive mortality of the test bees prior to the pesticide application
precluded their use for bioassay evaluations.
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o
1
o
8
O
2
O
9
LETTUCE
X.,
015
o
22
O
16
O
23
n n
,Bardin Elementry
School
O
5
O
12
O
26
O
6
O
13
O
20
FALLOW
O
27
O
7
G
14
O
21
O
28
O
33
O
34
O
35
Ijzsari \
_J ^037
.;j|| aaa ati j
FARM LABOR RESIDENCES
F////I
a n
O38(POND)
O39 O40
Alisal f-,oaa
© O
41 42 43
RESIDENTIAL AREA
FALLOW
O
44
O
45
LEGEND
PAVED ROAD
UNPAVED ROAD
RESIDENCE
SAMPLE SITE
(ANALYSIS PERFORMED)
O SAMPLE: SITE
(ANALYSIS NOT PERFOMCD)
MAP NOT TO SCALE
MIXING-LOADING SITE
©
46
O47
Jj«_AIRCRAFT SERVICE
BUILDING
Figure 2. Sicilian Locafions - Alonfcroy Counfy, California
May, 1977 (for additional tatnpling silo* loo Figuro 3.)
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POND
El E3 H Ea
HOME RANCH
All SAL
HIGH SCHOOL
©51
o
7
O
14
O
21
O
28
«
35
'LABOR RESIDENCES
O38IPONO)
O39
O40
BX^0 0 A
41 42
<$i* RESIDENTIAL AREA
O
44
O
45
FALLOW
LEGEND
1 '' " PAVED ROAD
i. ..; UNPAVEO ROAD
Q' .RESIDENCE
O SAMPLE SITE
(ANALYSIS PERFORMED)
O SAMPLE SITE
(ANALYSIS NOT PERFOMED)
UAP HOT TO SCALE
.MIXING-LOADING SITE
O
48
AIRCRAFT SERVICE
BUILDING
Figure 3. Additional Station Locations
'Monterey County, California May, 1977
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12
Table 1
SAMPLING STATIONS AND DEVICES
Monterey County, California
May 1977
Station
No.
1-17
18
19-23
24
25
26
27
30
31
32
33-35
36
37
38
39-46
47
48
49
51
Indicator
Cards7
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
X
High-Volume Water
Sampler
X
X
X
t
X
X
X
X
X
X
X
Soil
X
X
X
t Kromeeote, Tliermofax3 Linagraph.
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A. EPA mobile meteorological
laboratory.
B. Two-meter temperature probe
with anemometer and weather
vane.
Figure 4. EPA weather monitoring station.
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V. USE OBSERVATION
PRE-APPLICATION
Detecting Infestation
The agricultural advisor examined the study site on April 29, 1977.
He determined infestation by a random examination of several lettuce
plants throughout the field. According to the advisor, it is character-
istic for an insect infestation to begin in the same portion of the
fields as it has in the past several years. Therefore, past history and
experience with a particular field'serve to aid in determining potential
pest problems.
The examinations showed an infestation of aphids. To control these
pests, the advisor recommended aerial application of a mixture of 1.8
liters/ha (1.5 pt/acre) of PhosdrinME, 2.7 kg/ha (0.5 Ib/acre) of
Dipel** and Nu-Film-P*** at 0.29 liters/ha (0.25 pt/acre). Phosdrin was
suggested to kill the aphids; Dipel would prevent future larvae in-
festations; and the Nu-Film-P, a "sticker-spreader," would prevent
erosion of the pesticide mixture from foliage during rainfall or over-
head irrigation. An application rate of 140 liters/ha (15 gal/acre) was
specified.
* Phosdrin is a registered trademark of Shell Chemical Company;
EPA Registration No. G973-12AA.
** Dipel is a registered trademark of Abbott Laboratories; EPA.
Registration No. 275-18-AA-50516.
*** Nu-Film-P is a registered trademark of Miller Chemical and Fertiliser
Corporation; California Registration No. 72-50003-AA.
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15
The landowner was notified on April 29, 1977, that the intended
application was to occur May 1, 1977. Precautionary requirements were
detailed on an Air Delivery Record addressed to the landowner, dated
April 29, which read "Do Not Harvest within 4 days from Application."
This precautionary period was more restrictive than label requirements.
The Phosdrin label stated that the harvest limitation for lettuce at a
dosage of 1.17 liters/ha (1 pt/acre) is 2 days; for 2.34 liters/ha (1
qt/acro) the harvest limitation is 4 days. It was noted also that the
Air Delivery Record called for application of pesticide to an 11 ha (27
acre) lettuce field. However, the aerial application work order re-
quested a mixture for 24 acres. The applicator intended to use extreme
care near the sensitive areas at the southwestern and western end of the
field. This area was not trimmed as closely as other borders of the
lettuce field. Therefore, EPA observers estimated that only 24 acres of
4
the field were treated. Since the amount applied was less than the
maximum concentration permissible by the pesticide label, and which
experience had shown to be effective, the advisor demonstrated good and
safe judgement, which was beneficial both economically and environmentally.
Pesticide Facility
The pesticide was applied by a local firm (advisor, formulator and
applicator combined). Corporate offices and pesticide storage facilities
were located in Salinas, California; the latter were visited by NEIC
personnel during a reconnaissance survey on March 16, 1977. The facility
was modern, clean, and well ventilated [Figure 5]. Chemicals were
arranged according to general types of compounds and further organized
into specific types and brands. Storage facilities contained well defined
passageways and adequate working space. The entire plant site was kept
under security conditions. Areas were properly defined as to contents of
buildings and containers. Precautionary signs included "No Smoking" and
"Authorized Personnel Only." The pesticide dealer appeared to be making
every effort to comply with Occupational Safety and Health Administration
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A. Outside storage area for weather
resistant containers.
B. Indoor pesticide storage
facility.
Figure 5. Pesticide storage facilities.
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17
(OSHA) requirements. Company officials indicated that all employees
routinely received physical examinations including acetylcholinesterase
(AChE) evaluations to determine if workers have been exposed to excessive
amounts of pesticide.
The mixing and loading site was at the east end of the Salinas,
California Municipal Airport, about 500 meters southwest of the study
field. The site included several fenced enclosures, belonging to
various pesticide companies, which were used for temporary storage of
used pesticide containers. The fenced storage facilities were properly
posted with precautionary signs and secured [Figure 6].
Mixing and Loading
At 0600 hours on May 1, 1977, the day of the scheduled pesticide
application, a nurse rig and company workers arrived at the mixing and
loading site. However, it was discovered that sabotage had been attempted
on several aircraft used for spraying pesticides. This incident necessitated
rescheduling the pesticide use observation to May 2.
At 0400 hours on May 2, 1977, the nurse rig was again dispatched to
the mixing and loading site and pre-application operations began. The
nurse rig consisted of a large capacity tank truck and a trailer containing
the mix tank. Attached to the truck were several 115- and 210-liter
(30- and 55-gal) drums containing pesticides.
The pesticide mixing and loading apparatus used by the applicator
was a closed system which complied with the State of California Pesticide
Worker Safety Regulations for pesticide transfer.4* With this type of
operation, the liquid pesticide concentrate was transferred by vacuum
into a measuring tank and then to the final spray tank without exposure
of personnel to the liquid pesticide. The system is capable of rinsing
the emptied pesticide container, also. For the larger-volume containers,
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Figure 6. Temporary storage facility for used
pesticide containers.
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19
the closed system was equipped with a "breakaway" suction tube which
left the exposed portion of the probe inside the partially emptied
containers. Additionally, the system permitted the transfer of toxic
dry materials to the spray tanks through a wettable powder box [Figure
7].
The mixing and loading operation was performed in an exemplary
manner. Only one worker performed the operations. This employee wore
proper safety equipment consisting of hat, long-sleeve coveralls, boots,
gloves, face shield and respirator. The worker appeared to be very
conscientious, neat and familiar with his job. Two batches of mixed
pesticide were prepared. First, approximately 380 liters (100 gal) of
water was pumped from the 5,700 liter (1,500 gal) capacity nurse rig
tank into the 1,020 liter (270 gal) stainless-steel mix tank. Next, 13
kg (6 Ib) of wettable, powdered Dipel was added to the hatch opening at
the top of the tank and the mixture was agitated; then 0.95 liters (0.25
gal) of the "sticker-spreader," Nu-Film-P, was added.
The mix tank hatch was closed and 8.5 liters (2.25 gal) of Phosdrin
was pumped from a 115-liter (30-gal) drum to the mix tank through the
closed system. Water was then added to the mixture to obtain a final
volume of 760 liters (200 gal). Water and Phosdrin were pumped through
the closed system only. A calibrated sight tube was used for accurate
measurement. The only observable aerosol that occurred was when the
wettable powder, Dipel, was poured into the mix tank hatch opening.
Hov/ever, the loss was very minimal. All hazardous material transfer and
rinse operations were performed by the worker using a console panel of
valves. The aircraft pilot did not participate in the mixing and loading
operations, and remained a safe distance away from the work area.
The mixture was agitated for approximately 20 minutes before it was
pumped into the aircraft spray tank. One hundred gallons of mixture was
added to the spray tank. Each batch provided for two 380-liter (100-gal)
loads of pesticide mix.
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A. Helicopter being loaded from
nurse rig.
B. Portion of closed mixing system
showing console panel of valves
for liquid pesticides (top) and
wettable powder box (bottom).
C. Cutaway of 19 liter (5 gal) con-
tainer showing breakaway probe.
Exposed portion of probe remains
inside the sealed container.
Figure 7. Mixing and loading.
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21
A heavy-gauge flexible hose was used to pump the spray mix into the
aircraft tank. No visible leakage occurred. When the hose was uncoupled
from the aircraft, only a few drops of liquid were seen to drip onto the
ground. During the aircraft loading activity, pesticide formulation
samples were collected for comparison with labeling and other applicable
regulations. Later analysis of these samples revealed that the formulations
were chemically in compliance with State and Federal regulations.
Phosdrin concentrate analysis revealed label claims to be accurate.
The use of the closed system of pesticide transfer would be desirable
in all commercial pesticide mixing operations. The system appears to
provide worker safety features that far exceed batch mixing procedures.5.6>7.8
It affords fewer precautionary measures, and in hot and humid weather it
is beneficial to worker safety and comfort. The system reduces the
4
number of health examinations that would be otherwise necessary, because
workers have less potential exposure to toxic chemicals.
FIRST APPLICATION
Preparation
On April 30, 1977, high-volume air samplers were placed on and
surrounding the target field at eight locations [Figure 8]. On May 1,
these automatic samplers were operated for approximately 2 hours to
collect ambient air which would be analyzed later for background levels
of Phosdrin. Hater samples were collected for the same purpose during
this time, also.
Approximately 3 hours before the scheduled pesticide application on
May 2, drift indicator devices were placed in and at various distances
from the lettuce field. Station site locations were selected to
monitor potential contamination of the surrounding area. The indicator
devices consisted of Kromecote, Linagraph and Thermofax cards fastened
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Figure 8. (I to r) Platform containing spray
droplet cards (vertical placement of
cards not shown); high-volume air
sampling device.
Figure 9. Protected worker examining high-
volume air sampling device.
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23
both horizontally and vertically to wooden racks. High-volume air
samplers were started.
Members of the observation team were stationed at strategic locations
near the field to observe the application. All team members were wearing
appropriate safety equipment consisting of long-sleeve, tightly woven
coveralls, hats, boots, gloves, eye shields and canister-type respirators
[Figure 9].
Application
The application began at 0705 hours on May 2, 1977. NEIC weather
station data indicated winds were calm, with an occasional northeast
wind of 3.2 km/hr (2.0 mph). Ambient air temperature was 10.4°C at both
2 and 10 meters.
The aircraft used was a Bell helicopter-47-G5. The 11 m (36 ft)
spray boom was equipped with 32 Fan Jet* nozzles evenly spaced [Figure
2
10]. Boom pressure was set at 2.9 to 3.2 kg/cm (42 to 45 psi). The
aircraft operated at a speed of 61 to 65 km/hr (38 to 40 mph) approximately
1.2 m (4 ft) above the field surface [Figure 11]. Passes were made in a
southwest to northeast direction, parallel to the lettuce rows and
returned in a northeast to southwest direction. The pilot made a total
of sixteen passes, two of which were used to trim the northeast end of
the field. Two loads of the pesticide mixture were sprayed, averaging 5
minutes per load, with a 5-minute period to refill the helicopter spray
tank between loads. The aircraft pilot was extremely careful to avoid
spray drift into the farm labor residential areas. During each pass,
spraying was terminated more than 30 m (100 ft) before reaching the
southwest end of the field where the residences were located. No instance
of visible drift was seen to enter the sensitive areas surrounding the
field during the first portion of the application.
Fan Jet is a registered tradar&rk of Delavan Manufacturing Company.
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Figure 10. Bell helicopter equipped with spray
boom.
Figure 11. Aerial pesticide application at the
1.2 meter flight level.
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25
When approximately one-half the field was treated, the jilot
reported a gasline leak on his aircraft. The application could not be
completed until the malfunctioning helicopter was repaired; consequently,
the spraying operations were discontinued temporarily.
Operation of all high-volume samplers was discontinued within one
hour after the termination of this partial pesticide application.
SECOND APPLICATION
Preparation
After the first spraying operation had occurred, it was evident
that the area sprayed was much less than the field area that the EPA had
set up to observe. Contact was made with the applicator who indicated
that the lettuce crop consisted of two fields and that the southern
field was the application target area. Since winds were relatively calm
and from the northeast at the time of application, and the nearest and
farthest station locations bordering the northeastern end of the field
were more than 120 and 490 m (400 and 1,600 ft) from the target field;
it was improbable that drift could be effectively measured at the existing
stations. Sampling equipment locations were adjusted to more closely
monitor the actual target field. Operation of high-volume air samplers
was initiated once again within 1 hour before the second application.
Application
The second spraying operation began at 1050 hours. The pilot
performed the second application in a manner similar to the first. Two
loads applied in ten passes by the helicopter were sprayed onto the
remaining untreated portion of the field; two passes were used to trim
the southwestern edge of the field next to the sensitive areas.
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26
MEIC weather station data indicated that wind direction was extremely
variable with an average speed of 3.2 km/hr (2.0 mph) throughout the
second application. At the start of the application, wind direction was
north to south at 4.8 km/hr (3.0 mph). The spraying required approxi-
mately 20 minutes. During this time, wind direction changed to north-
easterly, into the farm labor residential area.
During the operation, the EPA team observed visible drift passing
into two sensitive areas. In one instance observers reported a drift
cloud passing into the farm labor residences as the aircraft was pulling
up to avoid the residence area. On another occasion a cloud was observed
being carried by wind currents into the residential area after the spray
boom had been shut off. Finally, drift was seen to enter the school
yard as a result of the vortex from the helicopter as the pilot sprayed
the edge of the field.
POST-APPLICATION
Samples of water and soil were collected within 3 hours after
application. Soil samples were collected on the school yard and at the
farm labor residences near stations 30, 31 and 37. Water samples were
collected from ponds at stations 38 and 51. Samples collected from
station 51 were used for analyses to determine Phosdrin as well as other
pesticide residues that might be persisting in surface waters. The
remaining post-application samples were used to determine drift beyond
the target field. High-volume air samplers were operated for 3 hours
following pesticide spraying. Other drift sampling systems were col-
lected within 3 hours after application was completed.
The ambient air temperatures and the dewpoint temperatures were ex-
actly the same for 5 hours preceding the application. This weather con-
dition resulted in heavy dewfall the morning of the pesticide application,
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27
Consequently, all indicator cards became saturated with moisture, pre-
cluding pesticide spray characterization by droplet impressions on the
cards. Nevertheless, residue analyses of the Thermofax paper confirmed
drift of Phosdrin beyond the lettuce field.
All stations located within 6.0 m (20 ft) of the field showed
measurable residues [Figure 2, Table 2]. Pesticide drift was detected
on Thermofax paper 90 m (300 ft) east of the field at station 12 and 20
(0.25 and 0.2 ug, respectively) on the fallow ground. Measurable drift
residue was detected at stations 31 and 36 in the elementary school yard
and at stations 37 and 38 in the farm labor residences. Thermofax cards
at station 31 revealed 0.2 ug of Phosdrin. A Phosdrin level of 0.8 yg
was measured at station 37 (farm labor residences) and 6.6 ug was detected
on Thermofax paper at the pond near station 38. A post-application
water sample at station 38 contained a Phosdrin level of 0.9 pg/1.
Analyses of soil samples collected in the school yard at stations
30 and 31 showed pesticide residue levels of 0.02 ug/g. A soil sample
collected near station 37 (farm labor residences) contained 0.03 yg/g
Phosdrin residue.
High-volume air samplers were operated at eight locations on and
near the field at stations 18, 24, 26 and 32 [Figure 2]. Additionally
air-filtering devices were placed at locations remote from the field to
monitor potential pesticide contamination of sensitive areas (stations
36, 37, 47 and 48). These automatic samplers collected a composite air
sample during and following the pesticide applications.
The high-volume filtering device, operated at station 18, 6 m (20
ft) off the northeastern end of the field, collected the largest amount
of Phosdrin drift (580 ug). This occurred as a result of heavy spraying
as the helicopter passed directly over the sampling device. The next
largest amount was found at station 32, about 30 m (100 ft) into the
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Table 2 28
PESTICIDE RESIDUE ANALYSES (PHOSDKIN)
Monterey County, California
Hay 1977
Station
Ho.
4
6
7
9
11
12
13
14
15
17
18
19
20
22
23
24
25
26
28
31
33
34
35
36
37
38
41
42
43
45
46
18
24
26
32
36
37
47
48
38
51
30
31
37
Sample Phosdrin
Type Residues
THERKOFAX PAPER (uq)
NDf
NO
NO
NO
... NO
Vjj 0.20
H = 0.25
NO
NO
ND
V = 3.5
H = ND
V = 12
H = 35
V = 0.20
H = 0.20
H = 0.20
V = 0.20
ND
ND
V = ND
H = 0.80
V = 120
H = 120
V = 0.35
H = 0.75
ND
V = 0.20
H = 0.20
V = 0.25
H = 0.20
ND
ND
ND
V = ND
H = 0.80
V = 6.6
H = ND
ND
ND
ND
ND
ND
HIGH-VOLUME FILTERS d,q)
580
60
140
190
25
72
6.5
8.0
ENVIRONMENTAL SAMPLES
KaterTT/D 0.90
Pesticide Scan ND
Soil (yg/g) 0.02
0.02
0.03
Detection
Limits
0.20 pg
0.2 yg
0.2 ug/1
0.004 pg/g
t AD = Hone i!atooted
tt V - Vertical position
ttt H = Horizontal position
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29
field (190 yg). The two devices at stations 36 and 37, on top of the
elementary school about 90 m off the field, and on top of the farm labor
residences 15 m off the field, collected 25 and 72 yg of Phosdrin,
respectively. High-volume air sampling devices near the Salinas Municipal
Airport and on top of the Alisal High School contained 6.5 and 8.0 yg of
Phosdrin, respectively [Figure 3]. However, these residues could not be
attributed directly to the observed application, and may have resulted
from applications in other areas because analyses of indicator cards
between these areas contained no detectable Phosdrin residues.
Observers noted that spraying operations were occurring early on
May 2, 1977, by another applicator approximately 0.8 to 1.6 km (0.5 to
1.0 miles) north to northeast of the target area. The pesticide applied
at this time was not determined; however, drift contamination detected
atop the high school could have resulted from these applications. A
possible explanation of the residues collected at station 47, near the
airport, is that this contamination may have resulted from spray droplets
falling from one or more of numerous aircraft either leaving or returning
to the airport mixing site.
Since irrigation water is largely recirculated in the Salinas
Valley, a water sample was collected from a remote pond approximately 4
km (2.6 miles) northeast of the target field. A scan for common chlori-
nated pesticides was performed to determine if the high intensity pesticide
applications in the area resulted in a persistence of some of these
compounds. Chemical analyses for many of the more persistent pesticides
failed to reveal identifiable pesticide residues.
Phosdrin is one of the most toxic organophosphate pesticides and is
categorized Class I under FIFRA regulations. Label precautions warn
that the material "should not be applied to areas occupied by unprotected
humans or beneficial animals." During this application, the elementary
school was in session with numerous children present in the playground
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30
near the target field. Additionally, the farm labor residences were
occupied, and unprotected children and adults were potentially exposed
to spray drift. Also, numerous vehicles were observed traveling the
farm roads bordering the target field.
The Phosdrin residues detected on the school yard and in the
private residences were found to be lower than acceptable tolerance
o
limits on lettuce eaten raw (0.5 mg/kg);2 cr 0.1 mg/m of air (8-hr/day,
40 hr/wk occupational exposure) in working environments.3 Reports
received from school officials showing no increase in absenteeism
indicated that the observed application had no discernible acute impact
upon the health of the elementary school children. Nevertheless, the
fact that drift cannot be completely controlled under any conditions
creates a potential hazard when pesticides such as Phosdrin are being
sprayed. Highly sensitive areas in close proximity to fields receiving
spray should be protected. The field should be treated on weekends
while school is not in session; residents should be notified and pro-
tected; and roads leading into an area should be posted or closed.
Currently, California has a permit system in effect in which all of the
above issues should be addressed.1
CLEANUP AND DISPOSAL
The Company had good cleanup and disposal facilities. Empty con-
tainers and refuse were placed aboard the nurse rig and returned to the
plant for disposal. The closed system that was used for mixing and
loading pesticides provided immediate and adequate rinsing of empty
containers. At the plant site, 5-gallon containers were flattened by a
mechanical crusher. This procedure ensured against accidental reuse of
these containers. Larger drums were recycled. Other pesticide con-
tainers and general refuse were hauled to one of three dump sites in
Monterey County for disposal. California State and County agencies
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31
assume responsibility in monitoring these sites for proper security,
handling and burial of containers.
MEIC personnel visited one of the Class II dump sites March 16,
1977. This sanitary landfill does not accept containers that are used
for Class I materials unless they have been properly rinsed. The site
visited contained proper signs explaining the conditions necessary
before acceptance of the Class I containers [Figure 12].
Because cleanup of pesticide residue in the aircraft tank was
delayed, it was not observed by the EPA inspectors. According to the
pilot, when cleanup occurs, the mix tank is rinsed with approximately
150 liters (40 gal) of dilution water. The dilution water is then
pumped into the aircraft spray tank and applied to the field that was
treated with the parent mix.
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tf CSPWBUE AT i
THIS LANDfSU..
Ml CONTAiHBS USE&
FORMSCCHB^MS
MUST HAVE Km «*»
ECBEFQtt
A. Posted entrance to sanitary
landfill.
B. Disposal area for used pesticide
containers.
Figure 12. Sanitary landfill, Monterey County.
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VI. EVALUATION OF METHODS
SPRAY DROPLET CARDS
The use of spray droplet cards to determine drift characteristics
and spray droplet size was not successful during this study. However,
the limitations of these devices were due to local environmental conditions,
not the insensitivity of the cards. Heavy dewfall occurred prior to the
first application and saturated the indicator cards. This masked spray
droplet impressions and precluded droplet-size analyses.
Residue analysis of Linagraph and Kromecote versus Thermofax cards
indicated laboratory pesticide extraction efficiency for Thermofax was
superior. Results of pesticide residue recovery on Thermofax cards were
not intended to be absolute values. These were only used to record
relative amounts of drift detectable in different areas where drift was
of concern. The fact that the cards contained excessive moisture may
have caused the residue values to be conservatively low.
HIGH-VOLUME SAMPLING DEVICES
High-volume air sampling devices proved capable of capturing pesticide
drift. Pesticide residue is captured on a dry fiberglass filter. This
reduces the possibility of hydrolysis of pesticide residues; but it
increases the possibility of evaporation of highly volatile pesticides.
Therefore, values obtained from the high-volume samplers are qualitalive.
Relative values obtained are dependent upon time of operation and volume
of air filtered. The high-volume filters were useful in that they
detected relative amounts of residue in different areas.
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34
ENVIRONMENTAL SAMPLING
Residue analyses of water and soil were useful in substantiating
that drift occurred in the sensitive areas. It also indicated that the
pesticide may be translocated by these media.
OBSERVATION AND PHOTOGRAPHS
Observations by EPA team members were the most valuable tool in
substantiating the drift conditions. Photographs were most useful in
recording storage and disposal facilities and mixing and loading op-
erations.
PESTICIDE EFFICACY
The pest-control adviser used no standard procedure for evaluating
the efficacy of the pesticide treatment. A random method of observing
several lettuce plants was used. The advisor reported that the treat-
ment caused an effective and satisfactory kill.
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35
REFERENCES
1. State of California, January, 1977. Lous and Regulations, Study
Guide, for Agricultural Pest Control Advisor, Agricultural Post
Control Operator, Pesticide Dealer, Agricultural Pilot Examinations.
Dept. of Food and Agriculture, Agricultural Chemicals and Feed,
Sacramento.
2. U.S. Congress, July 1, 1976. Code of Federal Regulations: Title
40 - Protection of Environment; chap. I - EPA; Subchap E - Pesticide
Programs; Pt 180 - Specific Tolerances. Washington: U.S. Govt.
Printing Office.
3. Sunshine, Irving, ed. 1969. Handbook of Analytical Toxicology.
The Chemical Rubber Company, Cleveland, Ohio, p. 565.
4. February 2, 1977. Closed Liquid Pesticide Mixing System Require-
ments. Memo: from John C. Hnllis, Chief, Agricultural Chemicals
and Feed - California Dept. Food and Agriculture, Sacramento.
5. National Enforcement Investigations Center, Oct. 1976. Pesticide
Use Observations in Kent County, Delaware (June 2-7, 1976).
Denver: Environmental Protection Agency. EPA 330/2-76-032, 41 p.
6. National Enforcement Investigations Center, Dec. 1976. Pesticide
Use Observations, Leflore County, Mississippi (July 25-August
7, 1976). Denver: Environmental Protection Agency, EPA 330/2-7G-OS8,
26 p.
7. National Enforcement Investigations Center, Jan. 1977. Pesticide
Use Observations, Imperial Valley, California (August 22-31, 1976).
Denver: Environmental Protection Agency, EPA 330/2-77-001, 71 p.
8. National Enforcement Investigations Center, Jan. 1977. Desiccant
Use Observations, Ellis County, Texas (September 21-27, 1976).
Denver: Environmental Protection Agency, EPA 330/2-77-002, 41 p.
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APPENDIX
DESCRIPTION OF SAMPLING DEVICES AND METHODS
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A-l
DESCRIPTION OF SAMPLING DEVICES AND METHODS
SPRAY DROPLET CARDS
Spray card clusters were constructed by stapling Linagraph 480
(Light sensitive paper), Thermofax 209, type G40 (copy paper) and
Kromecote photographic paper onto 15x20 cm (6x8 inch) poster-board.
The poster-board clusters were attached with thumbtacks atop 30 cm
(12 inch) square wooden platforms at one meter heights. Vertically
positioned clusters were attached to the platform, with the flat side
containing cards facing the target spray area.
HIGH-VOLUME AIR SAMPLERS
The high-volume sampler uses a high speed vacuum pump to draw air
and airborne particles through a fiberglass filter. The system draws
approximately 1 m3/min (35 ft3/min) of air through the filter. After
gathering a composite sample, the filters were removed and folded into
a small jar to which 100 ml of distilled water was added. The sample
was then chilled on ice until analysis.
ENVIRONMENTAL SAMPLING
Samples of soil, water and sediment were collected by standard
methods and chilled until analysis.
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A-2
DESCRIPTION OF ANALYTICAL METHODS
Hi-Vol Filters
Water contained in the sample jars was decanted into a separatory
funnel. The high volume filters were removed and rinsed with additional
water which was also added to the separatory funnel. The water was
saturated with Nad, and extracted serially with two 50 ml portions of
ethyl acetate. The ethyl acetate was concentrated to 10 ml in a Kuderna-
Danish evaporative concentrator and analyzed using an alkali-flame gas
chromatograph.
Thermofax papers
The Thermofax papers were wrapped in acetone-washed aluminum foil
and individually packed in plastic bags for transit from the field to
the laboratory. The samples were chilled in ice from the time of col-
lection to the time of analysis. Each sample was dipped into 175 ml of
ethyl acetate for approximately 5 minutes. The ethyl acetate extract
was then filtered through a Whatman Number 1 filter paper into a
Kuderna-Danish evaporative concentrator. The extract was concentrated
to 10 ml and analyzed using an alkali-flame gas chromatograph.
Water
One liter of water was saturated with sodium chloride and extracted
two times with 100 ml and 50 ml volumes of ethyl acetate, respectively.
The combined extract was then concentrated to 10 ml in a Kuderna-Danish
evaporative concentrator and analyzed using an alkali-flame gas chroma-
ograph.
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A-3
Soil
Fifty grams of soil was weighed into an Erlenmeyer flask. Ethyl
acetate (150 ml) was added and the sample was shaken for 10 minutes.
The ethyl acetate was then decanted and the process repeated with another
150 ml of ethyl acetate. The extracts were then combined, filtered
through Na2S04, and concentrated. Extracts were then analyzed on an
alkali-flame gas chromatograph.
Pesticide Scan
A scan for common chlorinated pesticides was performed on a water
sample collected at station 51. The sample was serially extracted with
100 ml and 50 ml volumes of hexane*, concentrated to 10 ml on a Kuderna-
Danish evaporative concentrator, and analyzed on an electron-capture gas
chromatograph.
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