Paper Number: 01-1055
An ASAE Meeting Presentation
Engineering Controls for Safer Spraying - The
Results of a Survey into Awareness and
Acceptability
Mr. Michael J. Helms
Research Support Specialist, Department of Agricultural and Biological Engineering,
Cornell University, 330 Riley-Robb Hall, Ithaca, NY 14853-5701, mjh14@cornell.edu
Dr. Andrew J. Landers
Pesticide Application Technology Specialist, Department of Agricultural and Biological
Engineering, Cornell University, 316 Riley-Robb Hall, Ithaca, NY 14853-5701,
ajl31@cornell.edu
Written for presentation at the
2001 ASAE Annual International Meeting
Sponsored by ASAE
Sacramento Convention Center
Sacramento, California, USA
July 30-August 1, 2001
Abstract. Farmers and custom applicators are under great pressure when applying pesticides. An
increasing awareness of environmental pollution, along with worker pesticide exposure concerns, has
resulted in increased pesticide use legislation. Worker protection is extremely important and engineering
solutions to reduce worker exposure are coming to the market place. Exposure to hazardous
substances, such as pesticides, should either be prevented or adequately controlled. Control must, so far
as is reasonably practicable, be by engineering control methods. In 2000, on behalf of the United States
Environmental Protection Agency, Cornell University researchers conducted a survey to consider the
level of adoption and awareness of 14 different engineering controls in the US. Mail surveys of 46
equipment manufacturers, 44 state pesticide regulators, 42 state pesticide application training
coordinators, and 83 state pesticide enforcement agents were used to determine engineering control
availability and use.
Keywords. engineering controls, occupational health, pesticide application, safety, safety
devices, spraying
The authors are solely responsible for the content of this technical presentation. The technical presentation does not necessarily
reflect the official position of the American Society of Agricultural Engineers (ASAE), and its printing and distribution does not
constitute an endorsement of views which may be expressed. Technical presentations are not subject to the formal peer review
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Paper No. xx-xxxx. St. Joseph, Mich.: ASAE. For information about securing permission to reprint or reproduce a technical
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Introduction
Mortality resulting from pesticide exposure during application to agricultural crops is quite rare in the
Western Hemisphere, however numerous medical reports have documented pesticide related
illnesses. Proudfoot and Dougall (1988) commented that work related accidents were cause for
concern and are generally a reflection of a breakdown in communication, inadequate training or
generally poor supervision and working practices. Pesticide applicators recognize the risk associated
with handling pesticides. Perry et al (2000) in a survey of operators' attitude to risk found a disturbing
number of applicators believed that most pesticides would not be put into the marketplace if they were
dangerous to health. Familiarity breeds contempt! They also noted that for those respondents
correctly answering 9 to 14 of 18 pesticide safety knowledge items, 98.0% disagree that direct
exposure to pesticides is not harmful to human health. Similarly, of those respondents answering 15
to 18 of the knowledge items correctly, 98.6% of the respondents disagreed. Attitudes toward
personal protective equipment use were shown not to reflect this concern.
The sprayer operator is at risk from splashes of dilute pesticide during the washing out of the sprayer,
when folding booms and from spray drift, according to Turnbull et al (1985) and Landers (1989). The
time taken to measure and decant pesticides and for adequate washing out of the pesticide
containers and the sprayer tank after use is expensive and may well encroach upon the time available
for spraying. If the operator hurries these tasks then the chance of contamination increases. Landers
and Hill (1996) outlined several engineering solutions for reducing the risk of sprayer operator
contamination that could be adopted by farmers. Closed transfer systems, carbon cab filters and tank
rinsing systems are cited as good engineering controls to reduce the contamination hazard. As an
example of engineering control effectiveness, Brazelton and Akesson (1987) showed that the number
of pesticide related illnesses among mixer/loader workers in California decreased by 50% after the
introduction of closed transfer systems.
Governmental agencies both in the US and abroad have developed regulations on the use of
engineering controls to decrease applicators pesticide exposure. In the United Kingdom, the Control
of Substances Hazardous to Health Act (COSHH), Regulation 7 (2) requires that prevention or control
be secured by measures other than the provision of personal protective equipment (Landers, 1990).
Control, as much as reasonably practical, must be by engineering control methods. Protective
clothing is used as a last resort. Landers (1989), in his reports to the British Government, noted that
California had become the model for many Federal and State laws governing pesticide use. In 1973
the California Department of Food and Agriculture introduced regulations requiring that closed transfer
systems be used when mixing or loading Category 1 pesticides. (Category 1 pesticides are those
having the signal word "Danger.") Specific criteria were developed later and due to a dearth of
equipment, the regulations were not implemented until 1977.
Presently, there are no federal regulations that require engineering control use in agricultural pesticide
application. The EPA Worker Protection Standard for Agricultural Pesticides does not require
engineering control use, but allows an agricultural pesticide handler to omit some of the label required
personal protective equipment when using closed transfer systems or enclosed cabs that have built-in
respiratory protection (40 CFR 170.240 (2000); EPA, 1993). In a public registration notice to
manufacturers, producers, formulators and pesticide product registrants, the EPA (2000) has
indicated that in the future, engineering control use may be required as a way to mitigate the risks
associated with handling and applying certain pesticides. The type of controls required will depend on
the magnitude of the risk and the potential effects from exposure to the pesticide.
In 1999 the EPA issued a call for research on the current status of engineering controls in the US. In
response to this request, an interdisciplinary team at Cornell University surveyed a network of
application equipment manufacturers and distributors, state level pesticide regulatory officials,
pesticide applicator training coordinators, and state pesticide inspectors or agents. These
professionals were selected to help determine the current level of use and understanding of
2
engineering control methods and the application of engineering controls available in the US. The
study took place from January 1 to December 31, 2000.
Five areas of potential pesticide exposure and their related engineering solutions were addressed in
the survey. A total of fourteen different engineering controls were identified. The risk areas and their
engineering solutions are:
 Loading the sprayer - closed transfer systems, chemical induction systems, direct injection
sprayers, container rinse systems

Operator contamination at the boom - multiple nozzle bodies, hydraulic boom folding/extending
systems, diaphragm check valves, hand wash water supplies

Spray drift or contaminated clothing in the cab - cabs with carbon filtration, protective clothing
lockers on the sprayer

Spray drift - low-drift nozzles, air-assisted booms, twin-fluid (air and water) nozzles

Cleaning spray equipment - tank rinse systems.
Procedures
We developed our mailing lists using several sources. Manufacturers and distributors (from this point
on referred to as manufacturers) were identified through professional organization membership
rosters, farm publications and the Internet. State pesticide regulatory agency and pesticide applicator
training (PAT) coordinator contacts were determined from the membership rosters for their
appropriate professional organizations, the American Association of Pesticide Control Officials
(AAPCO) and the American Association of Pesticide Safety Educators (AAPSE), respectively. State
pesticide inspectors and field agents (referred henceforth as state pesticide inspectors) were identified
by randomly selecting ten states and requesting agricultural pesticide inspector or field agent names
and mailing addresses from the appropriate state enforcement agency. The states selected were
California, Montana, Idaho, Oklahoma, Kansas, Indiana, Ohio, Pennsylvania, New York, and South
Carolina. The total number of surveys sent and response rates are provided in Table 1.
Table 1. Survey Response Rates
Surveys
Surveys
Sent
Returned
Manufacturers/Distributors
104
46
State Pesticide Regulatory Officials
50
44
Pesticide Applicator Training Coordinators
50
42
State Pesticide Inspectors/Agents
108
83
Percent
Response
44.2
88.0
84.0
76.9
Each survey mailing contained a cover letter explaining the purpose of the study, a copy of the survey
form, and a postage-paid return envelope. Postcard reminders were sent out two weeks after the
original mailing to those individuals who had not responded. Approximately six weeks after the first
mailing, a replacement survey form along with another postage-paid return envelope was mailed to
non-respondents.
The surveys were tailored specifically to each survey group. The manufacturer survey contained a
total of 37 questions. The questions asked about the commodities the sprayers are manufactured for,
the areas of the US where the sprayers are distributed, current and future engineering control
demands and current engineering control innovations. The bulk of the survey asked manufacturers to
identify which sprayer types they manufacture (mounted (three-point hitch) boom, trailed boom, self-
3
propelled boom (including heavy-duty truck mounted), skid mounted, mounted airblast, and/or trailed
airblast sprayers) and if engineering controls are standard, optional or not available. The
manufacturers provided their responses based on three sprayer sizes: less than 250 gallons, 251 to
500 gallons and 501 gallons and larger. A total of 18 different sprayer categories were created for the
survey. Manufacturers were also asked to provide an estimated cost for available engineering
controls.
State pesticide regulatory officials were asked 8 questions to explore engineering control use
requirements in their state. Questions were asked concerning current and future engineering control
requirements, number of farm operations using engineering controls, engineering control training and
educational materials provided to their field inspection staff. Questions regarding proposed legislation
affecting pesticide application systems or handler/applicator safety were also asked.
The PAT coordinator survey contained 11 questions. Questions were asked about years of
experience in pesticide training, engineering control familiarity, availability of educational materials
and educational methods used. Are engineering control training sessions provided to extension
personnel and applicators? Are applicators interested in learning about engineering controls and
what is their perception of how many farms in their state use engineering controls?
The selected state pesticide inspectors were asked to answer 14 questions, most of which were
based on their observations of farm operators. The questions related to their familiarity with
engineering controls, observations of engineering control use and their recommendations, farm
operator engineering control familiarity and attitude toward their use, numbers of farm operations
adopting engineering controls, and factors used to select engineering controls.
Findings
Due to the large number of engineering controls included in the study, this paper will summarize the
results for only four of them - closed transfer systems, chemical induction systems, tractor/sprayer
cabs with carbon filtration and spray tank rinsing systems. The results for these four engineering
controls are fairly consistent with the others in the study.
Closed Transfer Systems
We found that most manufacturers and distributors see a slight demand for closed transfer systems.
As shown in Table 2, these systems are most often offered as optional equipment in 10 of the 18
possible sprayer categories. It should be noted that the survey responses most likely include
plumbing systems that allow sprayers to be connected to chemical pumps or bulk containers as well
as true closed transfer systems. Closed transfer systems were found to be unavailable on any 250gallon and less self-propelled sprayers or on most of the other sizes of self-propelled sprayers. For
companies reporting closed transfer system prices, the average cost is $395.00 per system. The
average costs for all sprayer types are provided in Table 3.
4
Table 2. Closed Transfer System Availability (Majority Responses)
Percent of
Availability
Sprayer Type and Size
Respondents
Standard
----Optional
Trailed Airblast - 250 gallons and less
75.0%
Mounted Airblast - 251 to 500 gallons
66.7%
Mounted Airblast - 501 gallons and above
66.7%
Mounted Boom - 501 gallons and above
58.3%
Skid Mounted - 501 gallons and above
57.1%
Trailed Boom - 250 gallons and less
54.5%
Trailed Boom - 251 to 500 gallons
53.3%
Trailed Boom - 501 gallons and above
50.0%
Trailed Airblast - 501 gallons and above
50.0%
Mounted Boom 251 - to 500 gallons
42.9%
Self Propelled Boom - 250 gallons and less
100.0%
Not
Available
Self Propelled Boom - 501 gallons and above
58.3%
Self Propelled Boom - 251 to 500 gallons
57.1%
Mounted Boom - 250 gallons and less
52.9%
Table 3. Closed Transfer System Average Cost
Sprayer Type
Average Cost
Mounted Boom
$171.33
Trailed Boom
$266.00
Self-Propelled Boom
$1125.00
Skid Mounted
$125.00
Mounted Airblast
Not Reported
Trailed Airblast
Not Reported
Only California requires the use of closed transfer systems for the most toxic pesticides (EPA
Category 1). No other states are expecting to adopt closed transfer system requirements in the
foreseeable future.
Most PAT coordinators (90.5%) have at least some familiarity with closed transfer systems. However,
in this group, 40.5% of the coordinators responded they are slightly familiar with them. "Very familiar"
was reported by only 11.9% of the respondents. Nearly two-thirds of the coordinators (64.3%) replied
that closed transfer systems are generally discussed1 in their educational literature. Training that
includes closed transfer systems is not provided to most pesticide applicators or extension
agents/educators, as reported by 42.9% and 61.9% of the coordinators, respectively.
According to the state pesticide inspectors surveyed, they felt that 84.5% of the farm operators have
some familiarity with closed transfer systems, 40.3% selecting the "familiar" response. They also
noted they see closed transfer systems used most often on up to 25% of the farms they visit. When
asked, inspectors felt farm operations of 1001-acres and larger would most likely adopt closed
transfer systems.
1
In the survey, a general discussion was defined as a paragraph or less. A detailed discussion was defined as a chapter or
entire bulletin or fact sheet.
5
Chemical Induction System
Most manufacturers (46.5%) currently see moderate demand for chemical induction systems. As
shown in Table 4, induction systems are most often available as optional equipment. Induction
systems tend to be unavailable on most smaller sizes (250 gallons and less) of mounted boom, skid
mounted, trailed boom and mounted airblast as well as 251-to 500-gallon skid mounted and trailed
airblast sprayers. Manufacturers noted an average chemical induction system cost of $720.00. Table
5 summarizes the average costs for chemical induction systems.
Table 4. Chemical Induction System Availability (Majority Responses)
Percent of
Availability
Sprayer Type and Size
Respondents
Standard
----Optional
Mounted Airblast - 501 gallons and above
100.0%
Self-propelled Boom - 501 gallons and above
75.0%
Trailed Airblast - 250 gallons and less
75.0%
Trailed Airblast - 501 gallons and above
75.0%
Self-propelled Boom - 251 to 500 gallon
71.4%
Trailed Boom - 501 gallons and above
68.2%
Mounted Airblast - 251 to 500 gallons
66.7%
Trailed Boom - 251 to 500 gallons
60.0%
Skid Mounted - 501 gallons and above
57.1%
Mounted Boom - 251 to 500 gallon
52.4%
Mounted Boom - 501 gallons and above
50.0%
Mounted Boom - 250 gallon and less
76.5%
Not
Available
Skid Mounted - 250 gallons and less
75.0%
Trailed Boom - 250 gallon and less
63.6%
Mounted Airblast - 250 gallons and less
62.5%
Skid Mounted - 251 to 500 gallons
60.0%
Trailed Airblast - 251 to 500 gallons
57.1%
Table 5. Chemical Induction System Average Cost
Sprayer Type
Average Cost
Mounted Boom
$566.22
Trailed Boom
$462.33
Self-Propelled Boom
$1150.00
Skid Mounted
$573.33
Mounted Airblast
$1237.50
Trailed Airblast
$1012.50
Currently, no state requires the use of induction systems. Three-quarters of the states surveyed do
not expect to require them in the future.
The majority of the PAT coordinators are unfamiliar with chemical induction systems with 61.9%
indicating so. Most coordinators (66.7%) indicated they do not discuss induction systems in their
educational materials. Training that includes information on induction systems is also limited. A high
percentage of coordinators (81.0%) noted they have not provided training to extension
agents/educators and 73.8% indicated they have not provided training to pesticide applicators.
6
State pesticide inspectors indicated that 59.8% of the farm operators have at least a slight familiarity
with induction systems, 36.4% of them selecting the "slightly familiar" response. Chemical induction
systems are used most often on up to 25% of the farm operations, as reported by 40.3% of the
inspectors. Much like closed transfer systems, most inspectors feel farm operations of 1001-acres
and larger would most likely adopt chemical induction systems.
Cabs with Carbon Filtration
Just under a third of the equipment manufacturers (32.6%) indicated they see a high demand for
operator cabs with carbon filters. Only those companies manufacturing self-propelled sprayers were
asked to provide cab availability information. Most self-propelled sprayer manufacturers offer cabs
with carbon filtration as standard equipment. One company who manufactures 501-gallon and larger
self-propelled sprayers offers optional cabs. Another company who builds 250-gallon or less selfpropelled sprayers does not offer cabs at all. Manufacturers were asked if their cabs meet the ASAE
S-525 standard for cab environment. Nearly two-thirds of the manufacturers (60.0%) indicate that all
their cab systems can meet this standard. Not enough data was provided to accurately assess cab
costs.
No state currently requires cabs with carbon filtration. California has taken the lead, in cooperation
with the EPA, to allow agricultural applicators to use ASAE certified cabs in place of label required
respirators. The California Department of Pesticide Regulation has developed a list of cabs meeting
this requirement. As for future requirements, nearly three-quarters of the remaining states (72.7%)
are not planning any. Minnesota noted that at the time of survey completion, they were working on a
policy related to cabs and might have it completed within 6 months.
Nearly all of the PAT coordinators (90.5%) indicated they have a slight familiarity with cabs with
carbon filtration. In this group, 47.6% said they are slightly familiar and only 11.9% noted they are
very familiar with them. The coordinators are divided in the level of information about cabs with carbon
filters they provide in their educational materials - 47.6% say they do not provide any discussion while
45.2% say they provide only a general discussion. Only 28.6% of the coordinators have offered one
or more training sessions to extension personnel. Pesticide applicators have received slightly more
training with 31.0% of the coordinators providing one or more sessions to them.
Nearly half of the state pesticide inspectors (49.4%) noted that up to 25% of the farms they visit use
operator cabs with carbon filters. The inspectors felt that 84.5% of the farm operators are at least
slightly familiar with this engineering control, 48.1% selecting the "familiar" response. Like many of
the other controls in the study, most inspectors feel that farms of 1001-acres and larger would be
most likely to use cabs with carbon filtration.
Spray Tank Rinse Systems
Most sprayer manufacturers (39.5%) see a moderate demand for spray tank rinsing systems. Table 6
summarizes tank rinse system availability. Tank rinse systems are only found as standard equipment
on 42.9% of the 251- to 500-gallon self-propelled sprayers. The remaining sprayer types show that
most companies offer tank rinse systems as an option. Tank rinse systems were found to have an
average cost of $718.60 per system. Table 7 shows the average cost for all sprayer types.
7
Table 6. Spray Tank Rinse System Availability (Majority Responses)
Percent of
Availability
Sprayer Type and Size
Respondents
Standard
Self-Propelled Boom - 251 to 500 gallon
42.9%
Optional
Trailed Airblast - 250 gallons and less
100.0%
Trailed Boom - 251 to 500 gallons
81.8%
Trailed Boom - 501 gallons and above
81.8%
Skid Mounted - 251 to 500 gallons
80.0%
Mounted Boom - 251 to 500 gallons
76.2%
Mounted Boom - 501 gallons and above
75.0%
Skid Mounted - 250 gallons and less
75.0%
Skid Mounted - 501 gallons and above
71.4%
Mounted Airblast - 251 to 500 gallons
66.7%
Mounted Airblast - 501 gallons and above
66.7%
Mounted Airblast - 250 gallons and less
62.5%
Mounted Boom - 250 gallons and less
58.8%
Trailed Airblast - 251 to 500 gallons
57.1%
Trailed Boom - 250 gallons and less
54.5%
Trailed Airblast - 501 gallons and above
50.0%
Not Available -----
Table 7. Spray Tank Rinse System Average Cost
Sprayer Type
Average Cost
Mounted Boom
$513.11
Trailed Boom
$701.85
Self-Propelled Boom
$1100.00
Skid Mounted
$939.33
Mounted Airblast
$662.50
Trailed Airblast
$662.50
None of the states responding to the survey currently require tank rinse system use. Most states
(70.5%) noted they do not plan to require these systems in the near future.
A total of 81.0% of the PAT coordinators indicated they have some degree of familiarity with tank rinse
systems, 40.5% stating they are familiar with them. Just over half of the coordinators (54.8%) noted
they provide a general discussion on tank rinse systems in their educational materials. Only 14.3%
said they provide detailed information. Nearly half of the coordinators (47.6%) pointed out they have
offered one or more training sessions to extension agents/educators that included tank rinse systems.
Pesticide applicator training sessions are slightly more available with 54.8% of the coordinators
offering one or more training sessions to them.
The majority of inspectors (40.3%) noted they see tank rinse systems used on up to 25% of the farms
they visit. Only 2.6% of the inspectors reported that all farms they visit use them. Inspectors felt that
87.1% of the farm operators had at least a slight familiarity with tank rinse systems, 37.1% of them
selecting "slightly familiar" as their response. Most inspectors feel farms of 501-acres and larger in
size would most likely use tank rinse systems.
8
Discussion
The survey results indicate that with a few exceptions, most spray equipment manufacturers are not
providing engineering controls as standard equipment. For the most part, manufacturers are offering
several engineering controls as options. Farm operators appear to have some awareness of
engineering controls, but are reluctant to use them despite their availability. Two questions arise from
this observation. If the engineering controls are optionally available, what will encourage farmers to
purchase an engineering control? How do we get manufacturers and farmers, to buy into safety and
the related costs of engineering controls? One way is through federal or state government adoption
of legislation requiring engineering control use to be prescribed on the pesticide label.
The survey also points out that engineering control education is deficient. PAT coordinators have
developed written materials that include engineering control discussions, but the discussions tend to
be general (one paragraph or less) in nature. Very few states have detailed engineering control
educational materials available to farm operators or pesticide applicators. In a similar vein,
engineering control training for pesticide applicators and extension agents/educators is somewhat
limited. We would suggest that many pesticide application coordinators do not know where to obtain
engineering control information to include in their presentation materials and information packages or
to respond to farm operator or pesticide applicator inquiries. Development of web-based engineering
control resources and training modules can help to fill this void, educating farm operators, pesticide
applicators, and extension agents/educators on the benefits of engineering controls.
Another question arising from our research is what is the best combination of personal protective
equipment (PPE) and engineering controls that should be used to maximize safety? Concern about
this balance may well be seen in preliminary results from a Cornell analysis of pesticide residues in
tractor and sprayer cabs. The results have indicated that pesticide residues on the tractor or sprayer
seat are 80 times greater than any other part of the cab. It is believed that operators are not removing
their chemical resistant suits before entering the cab, therefore transferring pesticide residues from
the suit to the seat. This should cause concern since tractors are used for other farm tasks and could
result in contamination of unknowing tractor operators. Contamination can be prevented if protective
clothing lockers mounted to the sprayer or tractor were used to place contaminated clothing in before
operators enter the cab.
Conclusion
As the results of this study show, spray equipment manufacturers need to be encouraged to provide
engineering controls as standard equipment. Manufacturers should also be encouraged to supply a
wide array of basic engineering controls for their spray equipment and to promote them on economic
and safety grounds.
Most states do not require the use of engineering controls stricter than demanded by the federal
government. Labeling that requires the use of engineering controls should be considered.
Written materials and training programs for applicators and extension agents/educators is somewhat
limited. Work needs to be done to develop web-based information resources and training materials to
provide adequate engineering control information and training to pesticide applicators and educators.
Engineering control use in the field is relatively low. Most engineering controls are used on 25% or
less of the farms. The development of nationwide extension educational resources will improve
awareness of engineering controls among educators and growers alike, helping to create a demand to
satisfy market developments offered by manufacturers. A reduction in operator exposure should
result from these efforts.
9
Acknowledgements
We wish to acknowledge the EPA Office of Pesticide Programs, Certification and Worker Protection
Branch for funding this project and the various participants who responded to our surveys.
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