Pesticide Application Methods Research Articles

Effects of charging voltage, application speed, target height, and orientation upon charged spray deposition on leaf abaxial and adaxial surfaces

Wastage of agricultural chemicals and ensuing environmental pollution is an issue, where ineffective spray deposition is a major concern with conventional pesticide application methods. Electrostatic spraying is known to be one of the most effective methods to improve leaf abaxial (underside) surface deposition, overall deposition, and distribution on the plant targets. Deposition of charged sprays on leaf abaxial and adaxial (upper) surfaces as influenced by the spray charging voltage (system), application speed (operational), target height and orientation (target) parameters was studied in the laboratory. An air-assisted electrostatic induction spray charging system attached to a moving carriage was used to apply charged spray at uniform application (ground) speeds. Spray deposition (101–71 μm NMD), determined using a fluorescent tracer technique increased with charging (0–5.5 mC kg −1) on leaf abaxial and decreased with charging on adaxial surface. The deposition was higher on abaxial (0.66–1.33 μg cm −2) at 30° below (horizontal plane) and on adaxial (0.78–1.79 μg cm −2) at 0° (horizontal) target orientation for lower (0.278 m s −1) application speed. At all target heights, abaxial deposition increased with charging voltage (0–4.0 kV) for medium application speed (0.417 m s −1) and adaxial deposition decreased with charging voltage for lower application speed (0.278 m s −1). The medium application speed with higher charging voltage was optimum for abaxial and adaxial deposition. The droplet velocity and charging voltage were the key factors for obtaining desired spray deposition on targets. All the selected factors including target orientation ( O), application speed ( S), target surface ( L), and charging voltage ( V), and their interactions except between O and S were significant at lower (0.35 m) and medium (0.65 m) target heights. All the factors and their interactions except between O and V were significant at higher (0.95 m) height. Electrostatically charged spray improved the underside (abaxial) and overall deposition. The deposition was substantially influenced by factors such as charging voltage, application speed, plant target height, and target orientation.

농용 무인헬리콥터의 원심클러치 설계 - 최적 설계치의 시뮬레이션 -

Aerial application using an agricultural unmanned helicopter was suggested for an alternative against current pesticide application methods. Centrifugal clutches play important roles in the performance and safety of the helicopter operation. A previous study analyzed and verified the power transfer theory of the guide type centrifugal clutch. Based on the clutch theory, optimal designs of the clutch became possible and feasible using a simulation method. Design criteria of the clutch were the power transfer capacity of 24.66 kW(33.5 PS) at the rated engine speed and the engaging range speed of 3,0003,500 rpm. Various designs were accomplished using the simulation. An optimal clutch was simulated by determining the values of spring constant and mass of friction sector, which were 94,700 N/m and 123.7 g, respectively. The design performed the power capacity of 24.86 kW(33.8 PS) and engagement speed of 3,069 rpm, meeting the design criteria. Using the designed clutch, an efficient transfer of the power would be possible for the unmanned agricultural helicopter.

Analytical Solution Describing Pesticide Volatilization from Soil Affected by a Change in Surface Condition

An analytical solution describing the fate and transport of pesticides applied to soils has been developed. Two pesticide application methods can be simulated: point-source applications, such as idealized shank or a hot-gas injection method, and a more realistic shank-source application method that includes a vertical pesticide distribution in the soil domain due to a soil fracture caused by a shank. The solutions allow determination of the volatilization rate and other information that could be important for understanding fumigant movement and in the development of regulatory permitting conditions. The solutions can be used to characterize differences in emissions relative to changes in the soil degradation rate, surface barrier conditions, application depth, and soil packing. In some cases, simple algebraic expressions are provided that can be used to obtain the total emissions and total soil degradation. The solutions provide a consistent methodology for determining the total emissions and can be used with other information, such as field and laboratory experimental data, to support the development of fumigant regulations. The uses of the models are illustrated by several examples.

Pesticide sequestration in passive samplers (SPMDs): considerations for deployment time, biofouling, and stream flow in a tropical watershed

Semi-permeable membrane devices (SPMDs) provide an informative and cost-effective approach for monitoring contaminants in remote tropical streams. Estimation and interpretation of contaminant concentrations in streams derived from SPMDs can vary based on a number of environmental factors, including stream flow, biofouling, and deployment time. In three one-month long trials, SPMDs were concurrently deployed for 4, 15, and 28 days at three stream sites in an extensive agricultural area of southeastern Costa Rica. Water, bottom sediment, and suspended solids grab samples were also collected and several environmental variables were monitored at corresponding time intervals during each month-long study period. At all three sites, SPMD concentrations of the widely used insecticide chlorpyrifos increased with deployment time, with no relationship between SPMD biofouling and pesticide sequestration. Differences in SPMD chlorpyrifos sequestration among sites are likely due to differences in stream chlorpyrifos concentration rather than differences in SPMD sampling rates. The longer exposure period of SPMDs allowed for the detection of lower concentrations of chlorpyrifos, terbufos, and difenoconazole compared to water grab samples. In addition to the use of appropriate performance reference compounds (PRCs), other environmental variables such as stream turbidity, flow regime, stream morphology, and knowledge of pesticide application methods are important considerations for optimizing SPMD deployment and data interpretation in tropical regions.

Chlorothalonil exposure and cancer incidence among pesticide applicator participants in the agricultural health study

Background Chlorothalonil is a broad spectrum, non-systemic fungicide widely used to control diseases affecting over 50 fruit, vegetable, and agricultural crops. Despite its extensive use for over 30 years, little is known about the potential human carcinogenicity associated with the routine application of chlorothalonil. Rodent studies have shown evidence of renal tubular carcinomas and adenomas. We explored cancer incidence with chlorothalonil exposure using data from the Agricultural Health Study, a prospective cohort of licensed pesticide applicators in Iowa and North Carolina. Methods Licensed private and commercial pesticide applicators were recruited into this study from 1993 to 1997. Detailed information regarding pesticide use was obtained via self-administered questionnaires. Cancer incidence was followed through December 31, 2004. Chlorothalonil exposure was classified by lifetime exposure days and intensity-weighted lifetime exposure days, and then categorized into tertiles. The intensity-weighted lifetime exposure days metric was calculated based on a complex algorithm which includes pesticide application methods among other factors. This may increase or decrease exposure. Results Of the 47,625 pesticide applicators included in this analysis, 3657 applicators reported using chlorothalonil with a median of 3.5 application days per year. Chlorothalonil was not associated with overall cancer incidence, nor did we find any association with colon, lung, and prostate cancers—the only cancers for which we had sufficient numbers to explore associations. Conclusion We did not find any strong evidence for an association between chlorothalonil and the cancers investigated. Although animal studies have suggested renal cancer may be associated with chlorothalonil, we had insufficient data to evaluate this cancer.

농용 무인헬리콥터의 원심클러치 설계 - 동력 전달의 이론분석 -

An agricultural unmanned helicopter was suggested for an alternative to current pesticide application methods to solve such problems as high cost, low efficiency, shirking task and unsafe work. To pursuit this trend, researches on the development of unmanned helicopters have been accelerated in Korea as well. In this research, a guide type centrifugal clutch that plays an important role in the unmanned helicopter was studied. Theoretical analyses and experimental tests were conducted for designing an optimal clutches. Main design factors of the guide type centrifugal clutch were found to be spring constant, free length of spring, mass of friction sector, contact area, allowable pressure, number of friction sector, friction coefficient, radius of drum, and clutch arrangement. And these design factors could be the functions of engaging engine speed and desired power transfer capacity. The result of the single clutch test showed the power transfer capacity of 14.1 PS at 5,800 rpm and the result of the dual clutch test showed that the capacity of 17.7 PS at 5,600 rpm. These experimental results agreed well the theoretical simulations.

Risk assessment of pesticide usage by smallholder farmers in the Cagayan Valley (Philippines)

A significant increase in pesticide use has increased concerns about potentially adverse effects on human health and the environment, particularly in countries where regulations are not strictly implemented and farmers’ knowledge of safe handling procedures is often inadequate. This paper assesses the potential risk of pesticide use by smallholder farmers in the Cagayan Valley, North-East Luzon, the Philippines, by examining pesticide usage, application methods, pesticide drift and health effects among farmers with different levels of income and market access. About 104 farmers growing rice and corn were interviewed and spray drift and exposure of operators was measured when 22 rice farmers sprayed with water using their knapsack equipment. Twenty different pesticides freely sold in stores or markets were encountered in the study, 9 of which are classified as ‘highly hazardous’ or ‘moderately hazardous’ and at least 6 as restricted use pesticides. Farmers mostly at risk had the highest income and largest farms. By walking through crops, farmers’ legs were most seriously exposed to pesticide deposition. The experimental results agreed with farmers’ affirmative response to questions about their suffering various symptoms of poisoning. Estimates of pesticide concentrations in watercourses exposed to drift suggest that aquatic species will suffer adverse effects up to at least 2.0 m from field borders. Hazard quotients suggest that pesticide application rates are not toxic to honeybees exposed to drift up to 1.5 m from sprayed fields. Approval of pesticides needs to distinguish between restricted and general use pesticides. Recommendations are made for controlling pesticide use and its impacts, modifying the integrated pest management programme and redesigning pesticide policies.

Neurologic symptoms in licensed pesticide applicators in the Agricultural Health Study

Exposure to high levels of many pesticides has both acute and long-term neurologic consequences, but little is known about the neurotoxicity of chronic exposure to moderate pesticide levels. We analysed cross-sectional data from 18 782 Caucasian, male, licensed pesticide applicators, enrolled in the Agricultural Health Study from 1993 to 1997. Applicators provided information on lifetime pesticide use, and 23 neurologic symptoms typically associated with pesticide intoxication. Increased risk of experiencing >/=10 symptoms during the year before enrollment was associated with cumulative pesticide use, personally mixing or applying pesticides, pesticide-related medical care, diagnosed pesticide poisoning, and events involving high personal pesticide exposure. Greatest risk was associated with use of organophosphate and organochlorine insecticides. Results were similar after stratification by pesticide use during the year before enrollment, or exclusion of applicators with a history of pesticide poisoning, or high-exposure events. Use of pesticide application methods likely to involve high personal exposure was associated with greater risk. Groups of symptoms reflecting several neurologic domains, including affect, cognition, autonomic and motor function, and vision, were also associated with pesticide exposure. These results suggest that neurologic symptoms are associated with cumulative exposure to moderate levels of organophosphate and organochlorine insecticides, regardless of recent exposure or history of poisoning.

Effects of kaolin‐based particle film on spruce budworm (Choristoneura fumiferana (Lepidoptera: Tortricidae)) oviposition in the laboratory

A laboratory study conducted in 2003 determined the influence of a kaolin-based particle film (Surround WP Crop Protectant) on spruce budworm (Choristoneura fumiferana (Clem)) oviposition. Three concentrations (15, 30 and 60 g litre(-1) spray carrier) were applied to white spruce (Picea glauca (Moench) Voss). When presented with different paired choices of oviposition surfaces, spruce budworms laid very few egg masses overall and showed no significant (P < 0.05) preference between kaolin-coated and untreated foliage. During no-choice tests, spruce budworms were significantly (P < 0.05) less inclined to oviposit on the 60 g kaolin litre(-1) treated foliage than on the controls, but no kaolin treatment completely inhibited spruce budworm oviposition. Egg mass size and percentage hatch were unaffected by the kaolin treatments, and overall the percentage of egg masses laid on foliage was inversely proportional to treatment concentration. It is unlikely that kaolin-based particle film would be practical for wide use in natural forests without significant adaptations to current pesticide application equipment and methods. However, the technique might be feasible in selected urban settings.

The Validation of a Pesticide Exposure Algorithm Using Biological Monitoring Results

A pesticide exposure algorithm was developed to calculate pesticide exposure intensity scores based on responses to questions about pesticide handling procedures and application methods in a self-administered questionnaire. The validity of the algorithm was evaluated through comparison of the algorithm scores with biological monitoring data from a study of 126 pesticide applicators who applied the herbicdes MCPA or 2,4-D. The variability in the algorithm scores calculated for these applicators was due primarily to differences in their use of personal protective equipment (PPE). Rubber gloves were worn by 75% of applicators when mixing and 22% when applying pesticides, rubber boots were worn by 33% when mixing and 23% when applying, and goggles were worn by 33% and 17% of applicators when mixing and when applying, respectively. Only 2% of applicators wore all three types of PPE when both mixing and applying, and 15% wore none of these three types of PPE when either mixing or applying. Substantial variability was also observed in the concentrations of pesticides detected in the post application urine samples. The concentration of MCPA detected in urine samples collected on the second day after the application ranged from less than < 1.0 to 610 μg/L among 84 of the applicators who applied MCPA. The concentrations of 2,4-D detected in the urine samples ranged from less than < 1.0 to 514 μg/L among 41 of the applicators who applied 2,4-D. When categorized into three groups based on the algorithm scores, the geometric mean in the highest exposure group was 20 μg/L compared with 5 μg/L in the lowest exposure group for the MCPA applicators, and 29 μg/L in highest exposure group compared with 2 μg/L in the low exposure group for the 2,4-D applicators. A regression analysis detected statistically significant trends in the geometric mean of the urine concentrations across the exposure categories for both the 2,4-D and the MCPA applicators. The algorithm scores, based primarily on the use of PPE, appear to provide a reasonably valid measure of exposure intensity for these applicators, however, further studies are needed to generalize these results to other types of pesticides and application methods.

Semidiscrete pesticide transport modeling and application

A time-continuous and space-discrete method is proposed for three-phase (dissolved, adsorbed, and vapor phases) pesticide transport modeling in the vadose zone and a generalized semidiscrete solution is derived under conditions of heterogeneous media, unsteady flow fields, and space-time-dependent physical and biochemical processes concerning pesticide environmental fate. The developed model also takes into account pesticide runoff and erosion and pesticide transport in the plant canopy zone. The model is able to deal with various pesticide application methods commonly used in practice, including over-canopy, under-canopy, or any combined foliar and soil surface spray, as well as soil-incorporated applications. The hybrid semidiscrete solution method, formulated herein, incorporates analytical and numerical methodologies into a uniform, flexible modeling framework, which makes the model suitable for either screening-level investigations as a lumped model or detailed studies as a distributed model. Furthermore, the semidiscrete pesticide transport model is applied in the Orestimba Creek Basin, California, for evaluating the vulnerability of the hydrosystem to diazinon contamination. In accordance with the observations, the simulation demonstrates that diazinon exposure levels in the creek frequently exceed criteria for aquatic life, and many peak pulses even exceed the water-quality standard for human health. In the subsurface environment, however, high concentrations of diazinon are generally limited within the shallow soil. It is also found that the magnitude and timing of pesticide application and rainfall/irrigation dominate exposure levels of diazinon in both subsurface and surface environments.

Application methods and dosages of thiamethoxam in thrips control on tomato plants

Thrips is one of the most important vector species of the tomato spotted wilt tospovirus (TSWV) in Brazil. Two different pesticide application methods, drench x spray, using thiamethoxam were compared with commonly used insecticides for thrips control in tomato plants, Debora Plus. The experimental design consisted of a complete randomized block design with seven treatments and four replicates. Dosages of 150 and 200 g of a.i. per ha were used in just one drench application and 50 g of a.i. ha-1 sprayed, at weekly intervals, 48 days after sowing. The control efficacy of thiamethoxam was compared to diafenthiuron (400 g of a.i. ha-1), profenofos + cypermethrin (320+32 g of a.i. ha-1, respectively) and methamidophos (60 g of a.i. per hectolitre of water) in spray application. Cumulative number of plants with tospoviruses and the F. schultzei population from ten flowers per plot were registered. The mean cumulative number of plants with tospoviruses among treatments was not significantly different. No significant difference between thiamethoxam application methods and dosages on F. schultzei control, 24 days after application, were observed for thrips population. One drench application of higher dosages of thiamethoxam proved to be more environmentally advantageous than the pesticide applied at dosages of 50 g of a.i. ha-1 at weekly intervals. The vector control efficacy of thiamethoxam varied from 93 to 95%, independently of the application method and dosages. Diafenthiuron and profenofos + cypermethrin showed less efficacy (78 and 88%, respectively) but greater than those with methamidophos (71%). The products and dosages tested did not cause phytotoxicity in tomato leaves.

Improving Herbicide Application Accuracy in South Asia1

In 1998, Indian regulatory agencies approved the registration of CGA 184927, MON 37500, and fenoxaprop for postemergence control of isoproturon-resistant littleseed canarygrass. Herbicides used in rice and wheat before 1998 were generally mixed with sand or urea and were applied by hand. Foliar pesticide spray applications consisted primarily of insecticides and fungicides that were applied to high-value crops. These pesticides were often sprayed to runoff with backpack sprayers that were equipped with single hollow-cone or flood nozzles. Applicators walked through the fields, swinging the wands in sweeping motions resulting in uneven pesticide distribution and overapplication. The newly registered postemergence herbicides were applied with the same equipment and in the same fashion. After these applications, control of littleseed canarygrass was strikingly inconsistent, and the growers blamed the lack of control on the manufacturers. It was later clear that basic understanding of the application techniques was lacking. In response to this, an application training workshop was organized and conducted in India and Nepal in 2000. The workshops focused on teaching the participants how to use and fabricate multiple-nozzle booms, the importance of flat-fan nozzles, calibration, drift avoidance, and applicator safety. To date, approximately 3,000 farmers, extension agents, scientists, and industry representatives have attended more than 30 workshops. The participants were unanimously enthusiastic about the value of the workshops. Although simplistic, the adoption of this technology will significantly decrease the amounts of herbicides applied and will increase efficacy and efficiency.Nomenclature: CGA 184927 (proposed common name, clodinafop), 2-propynyl R-2-[4-[(5-chloro-3-fluoro-2-pyrdinyl)oxy]phenoxyl]-propanoate propynyl ester; fenoxaprop; isoproturon; MON 37500 (proposed common name, sulfosulfuron), 1-(4,6-dimethoxypyrimidin-2-yl)-3-[(2-ethanesulfonyl-imidazo[1,2-a]pyridine)sulfonyl]urea; littleseed canarygrass, Phalaris minor Retz. #3 PHAMI; rice, Oryza sativa L.; wheat, Triticum aestivum L.Additional index words: Backpack sprayers, pesticide application method, technology transfer.Abbreviation: I-HRAC, The Herbicide Resistance Action Committee of India.

A Modeling Framework for Estimating Children's Residential Exposure and Dose to Chlorpyrifos Via Dermal Residue Contact and Nondietary Ingestion

To help address the Food Quality Protection Act of 1996, a physically based probabilistic model has been developed to quantify and analyze dermal and nondietary ingestion exposure and dose to pesticides. The Residential Stochastic Human Exposure and Dose Simulation Model for Pesticides (Residential-SHEDS) simulates the exposures and doses of children contacting residues on surfaces in treated residences and on turf in treated residential yards. The simulations combine sequential time-location-activity information from children's diaries with microlevel videotaped activity data, probability distributions of measured surface residues and exposure factors, and pharmacokinetic rate constants. Model outputs include individual profiles and population statistics for daily dermal loading, mass in the blood compartment, ingested residue via nondietary objects, and mass of eliminated metabolite, as well as contributions from various routes, pathways, and media. To illustrate the capabilities of the model framework, we applied Residential-SHEDS to estimate children's residential exposure and dose to chlorpyrifos for 12 exposure scenarios: 2 age groups (0-4 and 5-9 years); 2 indoor pesticide application methods (broadcast and crack and crevice); and 3 postindoor application time periods (&lt; 1, 1-7, and 8-30 days). Independent residential turf applications (liquid or granular) were included in each of these scenarios. Despite the current data limitations and model assumptions, the case study predicts exposure and dose estimates that compare well to measurements in the published literature, and provides insights to the relative importance of exposure scenarios and pathways.

Effectiveness of interventions in reducing pesticide overexposure and poisonings

Objective: The objective of this paper was to review the effectiveness of interventions to reduce pesticide overexposure and poisonings in worker populations. Methods: We used the Cochrane Collaboration search strategy to search the following databases for articles that tested the effectiveness of interventions in reducing human pesticide exposure or poisonings: MEDLINE, EMBASE, and Occupational Safety and Health (NIOSHTC). Interventions considered included comparisons of pesticide application methods, pesticide mixing methods, worker education, biological monitoring programs, personal protective equipment (PPE) use, pesticide substitutions, and legislation. The outcomes of interest included biological monitoring measures or personal exposure monitoring indicating a reduction of pesticide exposure, observed increased use of PPE, reduction in lost workdays, and where possible, evidence of changes in pesticide poisoning rates as identified by registries and population surveys. Studies were reviewed in depth with special attention to size and study design. Results: Most studies evaluated exposure during differing configurations of PPE or during different mixing or handling methods. Most studies were small field tests of protective equipment involving less than 20 workers. Some studies examined biological indices of exposure such as cholinesterase or urinary metabolites. Studies showed that PPE was effective in reducing exposure. No controlled studies were found that addressed reducing pesticide poisonings. Conclusions: Changes in application procedures, packaging, mixing, use of personal protective equipment, and biological monitoring reduced pesticide exposure under controlled conditions. Cholinesterase monitoring can identify workers with a higher risk of overexposure. Most techniques were not tested in actual worksite programs. Interventions should be examined for their ability to reduce pesticide overexposure in actual working populations. No controlled evaluations of large legislative initiatives were found.

A modeling framework for estimating children's residential exposure and dose to chlorpyrifos via dermal residue contact and nondietary ingestion.

To help address the Food Quality Protection Act of 1996, a physically based probabilistic model has been developed to quantify and analyze dermal and nondietary ingestion exposure and dose to pesticides. The Residential Stochastic Human Exposure and Dose Simulation Model for Pesticides (Residential-SHEDS) simulates the exposures and doses of children contacting residues on surfaces in treated residences and on turf in treated residential yards. The simulations combine sequential time-location-activity information from children's diaries with microlevel videotaped activity data, probability distributions of measured surface residues and exposure factors, and pharmacokinetic rate constants. Model outputs include individual profiles and population statistics for daily dermal loading, mass in the blood compartment, ingested residue via nondietary objects, and mass of eliminated metabolite, as well as contributions from various routes, pathways, and media. To illustrate the capabilities of the model framework, we applied Residential-SHEDS to estimate children's residential exposure and dose to chlorpyrifos for 12 exposure scenarios: 2 age groups (0-4 and 5-9 years); 2 indoor pesticide application methods (broadcast and crack and crevice); and 3 postindoor application time periods (< 1, 1-7, and 8-30 days). Independent residential turf applications (liquid or granular) were included in each of these scenarios. Despite the current data limitations and model assumptions, the case study predicts exposure and dose estimates that compare well to measurements in the published literature, and provides insights to the relative importance of exposure scenarios and pathways.

Advances in Locust Spraying Technology

Whichever species of locust is considered, control strategy has always been limited by control technology. Early crop protection measures were confined to mechanical means. The development of synthetic insecticides and progress in application technology improved the efficacy of crop protection. Coupled with improved understanding of the biology and population dynamics of the major locust species, they also enabled strategic control in the form of plague and upsurge prevention.Baiting and dusting constituted simple but inefficient methods of pesticide application, but it was the development of ultra low volume (ULV) spraying that allowed man to interfere with the progression of locust plague cycles. The technology for ULV spraying has developed from simple early devices such as the exhaust nozzle sprayer to safer and more efficient sprayers equipped with rotary atomisers for hand-held, vehicle-mounted and aerial spraying use.Global positioning system (GPS) technology is a powerful new tool in locust control. The spatial accuracy and navigational guidance it provides simplify some of the most difficult tasks such as refinding targets and flying accurately spaced spray passes when no ground marker party is available. The technology also provides greater accountability in that the details of spraying operations can be recorded for later analysis.Despite these improvements in knowledge and technology, locusts still pose major problems due to their mobility, the remoteness and inaccessibility of their habitats and the inconsistent commitment to maintaining monitoring and control capacity for a sporadic and infrequent pest. Upsurges and plagues have occurred in recent years and are likely to continue to do so in the future, albeit with diminishing frequency and severity.

Characteristics of Pesticide Use in a Pesticide Applicator Cohort: The Agricultural Health Study

Data on recent and historic pesticide use, pesticide application methods, and farm characteristics were collected from 35,879 restricted-use pesticide applicators in the first 2 years of the Agricultural Health Study, a prospective study of a large cohort of private and commercial licensed pesticide applicators that is being conducted in Iowa and North Carolina. (In Iowa, applicators are actually “certified,” while in North Carolina they are “licensed”; for ease of reference the term license will be used for both states in this paper.) Commercial applicators (studied in Iowa only) apply pesticides more days per year than private applicators in either state. When the types of pesticides being used by different groups are compared using the Spearman coefficient of determination (r2), we find that Iowa private and Iowa commercial applicators tend to use the same type of pesticides (r2=0.88). White and nonwhite private applicators tended to use the same type of pesticides (North Carolinar2=0.89), as did male and female private applicators (Iowar2=0.85 and North Carolinar2=0.84). There was less similarity (r2=0.50) between the types of pesticides being used by Iowa and North Carolina private applicators. A greater portion of Iowa private applicators use personal protective equipment than do North Carolina private applicators, and pesticide application methods varied by state. This heterogeneity in potential exposures to pesticides between states should be useful for subsequent epidemiologic analyses using internal comparison groups.

Wind drifts of pesticide aerosols after various methods of pesticide application

Wind drifts of pesticide aerosols after various methods of pesticide application

Factors Associated with Self-Reported, Pesticide-Related Visits to Health Care Providers in the Agricultural Health Study

To investigate factors associated with pesticide-related visits to health care providers (i.e., doctor or hospital visits), responses to self-administered questionnaires received from 35,879 licensed restricted-use pesticide applicators participating in the Agricultural Health Study were analyzed. (In Iowa, applicators are actually certified, whereas in North Carolina they are licensed; for ease of reference, the term license will be used for both states in this paper.) The cohort reported a total of more than 10.9 million pesticide-application days. These applications were associated with one or more pesticide-related health care visits by 2,214 applicators (7.0% of the applicator cohort for whom health care visit data were available). The odds of a pesticide-related health care visit were increased for commercial applicators compared to private applicators [odds ratio (OR = 1.77; 95% confidence interval (CI), 1.52-2.06) and for applicators who used insecticides 70 times or more in their lifetime compared to those who used insecticides less frequently (OR = 1.43; CI, 1.26-1.63). After adjusting for the number of applications in a logistic regression model, significantly higher odds of health care visits were observed among North Carolina applicators compared to Iowa applicators (OR = 1.35; CI, 1.17-1.52), among applicators who mixed their own pesticides (OR = 1.65; CI, 1. 22-2.23), and among applicators who personally repaired their pesticide application equipment at least once per year (OR = 1.12; CI, 1.06-1.25). Significantly lower odds were found among female versus male applicators (OR = 0.68; CI, 0.46-0.99) and among applicators who graduated from high school versus those who did not (OR = 0.82; CI, 0.71-0.94 for high school graduates and OR = 0.79; CI, 0.68-0.91 for those with at least some college). Several methods of pesticide application to crops, seed, or stored grain were also associated with significantly elevated odds ratios of health care visits. These observations suggest that several steps can be taken to reduce the number of health care visits resulting from occupational exposure to pesticides. The implications of this pattern of pesticide-related health care visits may have etiologic implications for cancer and other chronic diseases.