Potential dermal exposure to operators applying pesticide on greenhouse crops using low-cost equipment

Application of ultra-low-volume spray for the control of vegetable disease in greenhouse: Investigation of formulation performance and potential dermal exposure

BACKGROUND

The use of pesticides in greenhouse vegetable cultivation is necessary and significant. However, traditional pesticide application methods such as the use of backpack sprayers with water-diluted pesticides have certain drawbacks, e.g., uneven distribution, high labor intensity, and safety risks.

RESULTS

In this work, fluazinam ultra-low-volume liquids (Flu-ULVs) were prepared using oily solvents as carriers. The effects of different oils on the physical properties of the preparations were investigated. The Flu-ULV can be sprayed directly using a hand-held ultra-low-volume (ULV) sprayer without dilution with water. Compared with commercial water-based suspension concentrates of fluazinam, the Flu-ULV samples showed better wetting of tomato leaves, better atomization, and more uniform droplet distribution. At a dosage of 300 mL/ha, the coverage rate of tomato leaves ranged from 32.47% to 79.3%, with a droplet deposition density of 556 to 2017 droplets/cm2. Application of Flu-ULVs provided 70.86% control efficacy against gray mold in tomatoes, which was higher than those achieved with reference products. Dermal exposure to Flu-ULVs was also evaluated in greenhouse experiments. The coverage rates for all parts of the operator's body ranged from 0.02% to 0.07%, with deposition volumes of 2.23 to 12.26 μg/cm2.

CONCLUSION

Ground ULV spraying of fluazinam was proved to be an effective and safe management option for the control of tomato gray mold in greenhouses. This study laid a foundation for the use of ultra-low volume spray to control vegetable diseases in greenhouse, especially those induced by high humidity environment. © 2024 Society of Chemical Industry.

Renal tubular dysfunction in greenhouse farmers exposed to pesticides unveiled by a panel of molecular biomarkers of kidney injury

Growing evidence suggests that chronic exposure to pesticides may cause adverse effects on the health of the exposed population leading to organ-specific toxicity, including kidney damage. Traditional markers used to assess renal function (glomerular filtration rate (GFR), and serum creatinine and cystatin C -Cys-C-) are inadequate to evaluate a potential subclinical renal impairment linked to occupational exposure to pesticides, since levels above the upper limit of normal only occur when renal damage is very extensive. The use of more sensitive biomarkers is therefore needed. This study investigated novel urinary biomarkers of kidney function (microalbuminuria, osteopontin (OPN), trefoil factor 3 (TFF3), β-2-microglobulin, neutrophil gelatinase-associated lipocalin (NGAL), and Cys-C), together with the aforementioned traditional serum biomarkers, to assess potential kidney damage in farmers exposed to pesticides in an intensive agriculture setting. The study population consisted of 175 greenhouse workers and 91 healthy control subjects from Almeria (Southeastern Spain), a major hub of greenhouse agriculture. Data were collected at two different time-points of the same crop season: a period with greater pesticide use (high exposure period) and another with lower pesticide use (low exposure period). Significantly higher urinary levels of OPN and TFF3 were found in greenhouse workers than in controls, and in the high pesticide exposure period compared to that of low exposure. These changes suggest a subclinical tubular damage linked to pesticide exposure. In contrast, microalbuminuria, GFR, serum creatinine and Cys-C failed to be associated with pesticide exposure, suggesting that glomerular function was spared. Increased OPN and TFF3 levels over time may suggest a gradual progression from tubular dysfunction to chronic kidney disease in the exposed population.

Mitigation of pesticide residue levels in the exposed dermal regions of occupationally exposed farmworkers by use of personal protective equipment

Unsafe pesticide handling practices with the limited use of personal protective equipment (PPE) by the Indian farming groups lead to an increased risk of exposure to pesticides. Therefore, a community-based follow-up study based on dosimeters, wipes, and hand-wash technique was carried out to evaluate the dermal exposure to pesticides and to analyze the impact of the usage of PPE on minimizing the exposure among the farmworkers of Rangareddy district, Telangana, India. Risk in terms of hazard quotient (HQ), hazard index (HI), and safety analysis as margins of safety was assessed. Farmworkers averaged 18 years of farming experience and showed resistance to adopting good agricultural practices. Ten pesticide residues were detected in concentrations ranging from 0.000 to 246 mg ml-1 in hand-wash, 0.000 to 198.33 ng cm-2 in patch dosimeter, and 0.000 to 1,740 ng cm-2 in wipe samples collected from farmworkers not using PPE. The second phase includes the intervention study results that revealed a significant reduction both in the concentrations and the number of pesticide residues detected in the hand-wash, patch, and wipe samples of the farmworkers who have used the PPE provided to them (p < 0.01). Furthermore, the probabilistic health risk assessment in terms of the HQ values ranged from 0.02 to 1029.82, and HI was >1, suggesting the non-carcinogenic risks associated with dermal exposure to pesticides among them. Additionally, the safety risk assessment in terms of the margin of safety suggests that they follow risky handling practices. The study confirms that farmworkers are exposed to pesticides and emphasizes the significance of using PPE in reducing the risk.

Sequential Indoor Use of Pesticides: Operator Exposure via Deposit Transfer from Sprayed Crops and Contaminated Application Equipment

Dermal transfer of pesticide residues to human skin due to contact with treated crops, treated surfaces, or contaminated surfaces is an important route of exposure for operators, workers and possibly for bystanders and residents. However, information on dermal transfer data is limited and mainly available for workers. The aim of the present study has been to generate both dermal exposure and transfer data related for operators involved in sequential tasks of mixing/loading and application of pesticides in a southern EU zone greenhouse. Exposure measurements were based on the principles of the whole-body dosimetry (WBD) method involving the use of cotton coveralls and gloves as dosimeters. Six field trials were conducted in three tomato greenhouses, on the island of Crete, Greece. The study results showed that the contribution of existing pesticide deposits on the treated crops, i.e., from an application conducted earlier the same day, was in the range of 8–16% for the application task and 0.9–18% for the mixing/loading task in relation to the measured total exposure to this pesticide during a short-term sequential application. The results of this study have been incorporated in the GAOEM (Greenhouse Agricultural Operator Exposure Model) included in the updated EFSA Guidance on the assessment of exposure of operators, workers, residents and bystanders in risk assessment of plant protection products. The low values of the pesticide amount penetrating the coverall (actual dermal exposure) in all cases highlight and confirm the need for the use of appropriate personal protective equipment (PPE) for operator safety.

Dissipation, residue, stereoselectivity and dietary risk assessment of penthiopyrad and metabolite PAM on cucumber and tomato in greenhouse and field

Penthiopyrad is a broad-spectrum fungicide with wide application in agriculture with preferential degradation of the S (+)-stereoisomer in soil. An understanding of the stereoselective fate of penthiopyrad is crucial for accurate food safety risk assessment. In this study, the dissipation, distribution, and dietary intake risk of penthiopyrad and its main metabolite (PAM) was conducted in cucumber and tomato samples under greenhouse and open field conditions. The half-lives of penthiopyrad in cucumber and tomato samples were < 8 days and the dissipation rates were higher in the open field than in the greenhouse. Due to the enantiomeric fraction data > 0.5, S (+)-stereoisomer dissipated slightly faster than R-(-)-stereoisomer. The residues of total penthiopyrad (sum of rac-penthiopyrad and PAM) were lower than the maximum residue limits in cucumber and tomato samples (risk quotients ≪ 100%). Therefore, the recommended penthiopyrad spraying method does not threaten vegetable cultivations and has negligible dietary intake risk.

LIDAR-based autonomous navigation method for an agricultural mobile robot in strawberry greenhouse: AgriEco Robot

<abstract> <p>This paper presents an autonomous navigation method for an agricultural mobile robot "AgriEco Robot", with four-wheel-drive and embedded perception sensors. The proposed method allows an accurate guidance between strawberry crop rows while automatically spraying pesticides, as well as detecting the end and switching to the next rows. The main control system was developed using Robot Operating System (ROS) based on a 2D LIDAR sensor. The acquired 2D point clouds data is processed to estimate the robot's heading and lateral offset relative to crop rows. A motion controller is incorporated to ensure the developed autonomous navigation method. Performance in terms of accuracy of the autonomous navigation has been evaluated in real-world conditions within strawberry greenhouses, proving its usefulness for automatic pesticide spraying.</p> </abstract>

Design and Construction of a Low-Cost Test Bench for Testing Agricultural Spray Nozzles

Droplet size distribution is probably the most important feature of a spray as it affects all aspects of a phytosanitary treatment, i.e., biological, environmental, and safety aspects. This study describes a low-cost laboratory test bench able to analyze agricultural spray nozzles under realistic conditions. The design of the equipment was mainly based on the ISO 5682-1 standard. It has a couple of 3 m long rails, along which the nozzle under test moves while spraying, controlled by a closed-loop position and speed controller. The drops were captured with three Petri dishes containing silicone oil, photographed by means of a digital single-lens reflex (DSLR) camera, and then analyzed with the ImageJ software in order to measure the usual spray parameters: the volumetric diameters, the Sauter mean diameter, and the number mean diameter. Spray trials and tuning of the system parameters were managed by means of a purposely designed user interface running on a Windows 10 PC. Some tests were carried out by using an Albuz ATR80 orange hollow cone nozzle at the working pressures of 0.3, 0.5, 1.0, and 1.5 MPa. The results about spray quality agree with the factory information, and the whole system, even if some aspects still need improvements, has proven reliable.

Spray performance assessment of a remote-controlled vehicle prototype for pesticide application in greenhouse tomato crops

Intensive horticultural production is a sector seeking to provide high-quality foods by means of safe and sustainable procedures in compliance with regulations. This requires improvements in the spraying technologies since currently plant protection products are applied by means of hand-held equipment due to its lower cost and easy maintenance. In order to fulfil these requirements, a remote-controlled vehicle prototype (ROBOT SPRAY) was used. After optimizing the spray profile and the air assistance system of the "ROBOT SPRAY" sprayer in laboratory, its performance using two different nozzle sets (full cone and hollow cone) with and without air assistance was compared with those of a spray gun in a greenhouse tomato crop. The spray deposition on canopy, spray coverage and losses to soil were assessed. The "ROBOT SPRAY" provided better penetration and coverage on the underside of the leaves while no improvement was shown with the use of air assistance. Overall, a higher spray deposition was observed for the full cone nozzles when compared to hollow cone nozzles.

Development of Personal Protective Clothing for Reducing Exposure to Insecticides in Pesticide Applicators

Wearing appropriate personal protective equipment during the application of pesticides is one method of reducing dermal exposure to pesticides. Thus, the aim of this research is to develop personal protective clothing (PPC) coated with gum rosin and investigate the efficiency of its level of protection against chlorpyrifos and cypermethrin. Comparison of the protection efficiency of each PPC with Tychem^® C coveralls was also investigated. Five commercially available cotton fabrics were chosen for tailoring the PPC, and then, the PPC was coated with a gum rosin finish to provide water repellence. The efficiency of the level of protection of the gum rosin-coated PPC against insecticides was tested in a laboratory (closed chamber). The remarkable findings were that the % protection efficiencies for all the PPC, with the exception of one, were not significantly different to those for Tychem^® C coveralls. The protection efficiencies ranged from 99.85% to 99.97% against chlorpyrifos and 99.11% to 99.89% against cypermethrin. Therefore, our results suggest that gum rosin-coated clothing provided satisfactory levels of protection against insecticides and could be considered as suitable protective clothing for pesticide applicators. Choice of an appropriate fabric for coating with gum rosin also needs to be considered. A further study in field conditions is warranted to confirm the protection efficiency in a working environment.

Considerations for cholinesterase biomonitoring in flower and ornamental plant greenhouse workers

Flower cultivation in greenhouses enhances productivity and ensures high-quality product supply throughout the year. However, under such protected environments, climate conditions are designed to favor flower growth and can intensify occupational exposure to pesticides. In this study, flower greenhouse workers were tested for cholinesterase inhibition, a valuable indicator of occupational exposure to organophosphate and carbamate pesticides. The quantified inhibition was also associated with working practices using these outcomes to explore ways in which provisions of regulatory Occupational Health Control Programs can be met considering the peculiarities of this working environment. Despite their preliminary nature, and considering that workers had not been previously tested, the obtained results suggested that the designed pre- and post-screening process, enabled biomonitoring of the exposed population. The pre-exposure sample was collected after 11 days from pesticide spraying and the post-exposure sample was collected no later than 10 days after pesticide spraying. AChE activity was significantly depressed in flower greenhouse workers, comparing pre- and post-exposure intervals. Nursery workers, often overlooked, presented greater inhibition of AChE activity. Such finding is consistent with effects believed to be associated with the described job and the way activities are conducted, once nursery workers are regularly exposed to low levels of pesticides owing to their continuous contact with sprayed crops. As predicted by Occupational Safety and Health Standards, establishing biomonitoring programs is achievable, despite the intensive use of pesticides. Quantification is important to target the exposed population but is not sufficient to assure good working conditions and avoid exposure. Administrative and working practices, such as job misclassification, non-compliance with national regulations for occupational health control, pesticide handling, lack of REI protocols, and unsuitable delivery of PPE, must be addressed. Anything less will contribute to worsening an already bleak picture in terms of occupational safety and health in flower and ornamental plant greenhouses.

Human exposure and mass balance distribution during procymidone application in horticultural greenhouses

The purpose of this study was to analyze the impact of procymidone application in periurban horticultural greenhouses, especially on workers (applicators and assistants) and soil and plastic mulching, when mechanically pressurized application systems were employed. The mean Potential Dermal Exposure (PDE) was measured using the Whole Body Dosimetry technique. The PDE for the applicators was 188 mL h⁻¹ ± 103 mL h⁻¹, and 14.7 mL h⁻¹ ± 6.3 mL h⁻¹ for the assistants. In the first case, the most exposed body sections were the upper right and left (46.8 mL h⁻¹ ± 23.4 mL h⁻¹; 47.0 mL h⁻¹ ± 23.5 mL h⁻¹) and lower (20.8 mL h⁻¹ ± 10.4 mL h⁻¹; 17.3 mL h⁻¹ ± 8.7 mL h⁻¹) legs, while in the case of assistants, hands and legs were the most impacted limbs. Regarding the Margin of Safety (MOS) during the mix and load stage, two of three pesticide preparations resulted unsafe, while for the applicators, six of six spraying operations were unsafe. For the assistants, five of five operations were safe, but three of them were close to the safety limit.

Procymidone distribution between drift (0.03% ± 0.07 %), applicator (0.20% ± 0.15 %), polyethylene mulching (8.5% ± 4.5 %) and soil (3.0% ± 1.1 %) was determined with respect to the total pesticide applied. Procymidone soil impact was also evaluated using Eisenia andrei behavioral tests, finding positive correlations between procymidone application and avoidance and reproduction tests.

The greenhouse work environment: a modifier of occupational pesticide exposure?

Greenhouses are enclosed structures which have various characteristics that enhance crop productivity, but the implications for workers' pesticide exposure and uptake are not well understood. A narrative literature review was conducted to explore the mechanism/s of interactions between greenhouse characteristics and occupational pesticide exposure. Using a "work", "worker" and "workplace" conceptual framework, the greenhouse environment (hot and humid microclimate, limited space and dense crop arrangements) combines with work characteristics (high work and pesticide use intensity, multi-tasking, predominantly manual spraying techniques and quick reentry to treated farms) to potentially increase occupational pesticide exposure, compared with open field farming. Greenhouse environments, are variable but have been shown to influence pesticide availability, route, pathways and frequency of exposure, deposition and distribution on a worker's body as well as use and performance of exposure control methods. Training programs can emphasize the differences in exposure potential between greenhouse and open field farming. Development of tailored guidelines for exposure control strategies to better suit the level of uniqueness of greenhouse agriculture seems warranted.