Assessment of field re-entry exposure to pesticides: A dislodgeable foliar residue study

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.

Association of immunotoxicological indices with lung cancer biomarkers in poultry, grape, and rose farming workers

Exposure to occupational hazards like dust, pesticides, diesel emission particles, or physical hazards in the agricultural sector is known to cause adverse health effects on farm workers. Our study aimed at addressing the association of immunomodulatory status with plasma levels of lung cancer biomarkers in farming population, attempting to recognition of vulnerable farming group. Blood samples from apparently healthy 51 chicken husbandry, 19 grape orchard, and 21 rose greenhouse workers were subjected to evaluate plasma levels of two representative lung cancer biomarkers, pro-gastrin releasing peptide (Pro-GRP) and cytokeratin fragment 19 (CYFRA 21-1). Peripheral blood mononuclear cells obtained from farmers were used for natural killer (NK) cell phenotyping and cytokines (interferon-gamma, IFN-γ and interleukin-13, IL-13) profiling in the culture supernatant. Compared to the rose greenhouse farmers, the grape orchard and chicken husbandry workers revealed a significantly upregulated plasma Pro-GRP and CYFRA 21-1 level. A low proportion of NK cells was observed among the female grape orchard workers and a lowered IFN- γ:IL-13 ratio was seen in the grape and chicken husbandry workers than the rose workers. Our findings imply that grape orchard and chicken husbandry workers have more disturbed immune homeostasis implicated with augmentation in the levels of lung cancer biomarkers than the rose greenhouse workers.

A new laboratory method to study the impact of leaf texture on pesticide dislodgeable foliar residues (DFR)

Pesticides are vital in meeting the challenge of feeding the rapidly increasing world population. However, it is crucial that they are used in a way that does not compromise the safety of humans or the environment. Non-dietary worker risk assessments consider the amount of residue which can be transferred from plant foliage to the skin or clothes, known as dislodgeable foliar residues (DFRs). DFR data scarcity due to the costly and seasonal characteristics of DFR studies is an obstacle to the extrapolation of DFR data to different crops/leaves. This paper validates a new proof-of-concept technique to investigate factors that may affect DFR (leaf texture) using the fungicide difenoconazole EC 10% as an example on various leaves (i.e., French bean, soybean, tomato, oilseed rape, and wheat). DFR was the lowest in the case of oilseed rape (31.0 ± 3.4%) and the highest in French beans (82.0 ± 2.9%). This significant difference in DFR in the findings of this study sheds light on the importance of the leaf surface as a major factor affecting DFR and supports the application of the laboratory method for more extensive data generation. More data generation would enable the extrapolation saving money and resources.

In vitro interaction of the pesticides flupyradifurone, bupirimate and its metabolite ethirimol with the ATP-binding cassette transporter G2 (ABCG2)

ABCG2 is an ATP-binding cassette efflux transporter that is expressed in absorptive and excretory organs such as liver, intestine, kidney, brain and testis where it plays a crucial physiological and toxicological role in protecting cells against xenobiotics, affecting pharmacokinetics of its substrates. In addition, the induction of ABCG2 expression in mammary gland during lactation is related to active secretion of many toxicants into milk. In this study, the in vitro interactions between ABCG2 and three pesticides flupyradifurone, bupirimate and its metabolite ethirimol were investigated to check whether these compounds are substrates and/or inhibitors of this transporter. Using in vitro transepithelial assays with cells transduced with murine, ovine and human ABCG2, we showed that ethirimol and flupyradifurone were transported efficiently by murine Abcg2 and ovine ABCG2 but not by human ABCG2. Bupirimate was not found to be an in vitro substrate of ABCG2 transporter. Accumulation assays using mitoxantrone in transduced MDCK-II cells suggest that none of the tested pesticides were efficient ABCG2 inhibitors, at least in our experimental conditions. Our studies disclose that ethirimol and flupyradifurone are in vitro substrates of murine and ovine ABCG2, opening the possibility of a potential relevance of ABCG2 in the toxicokinetics of these pesticides.

Development of a New Dislodgeable Foliar Residue Analytical Laboratory Method for Pesticides

The dislodgeable foliar residue (DFR) is the amount of pesticide that exists on foliage after the pesticide has dried and which could dislodge to the skin or clothes of workers and is a key parameter for non-dietary risk assessments required to demonstrate safe use for pesticide registration. DFR data in the literature are described as insufficiently reliable, limited, and encompasses considerable statistical uncertainties. The purpose of this article is to describe a newly developed laboratory method for the quantification of DFR with an illustrative example. The laboratory method reflected available field DFR methodology but involved controlled application of droplets to leaves and validation of the wash-off process used to remove the residue from the leaf surface before the analytical quantification. A very high level of accuracy (99.7-102.1%) and precision (±1.5%) was achieved. Residue data generated from the illustrated application of the method showed a robust normal distribution, unlike field studies. The method is deemed to be controllable, cost-efficient, and time-saving, taking hours rather than days. This enables the generation of more data to allow extrapolation between the generated data by investigating multiple factors that may influence DFR. An improved understanding of DFR could save time, money, and resources.

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.

Pesticide exposure of workers in apple growing in France

Objective

Although apple trees are heavily sprayed, few studies have assessed the pesticide exposure of operators and workers in apple orchards. However, these data are crucial for assessing the health impact of such exposures. The aim of this study was to measure pesticide exposure in apple growing according to tasks and body parts.

Methods

A non-controlled field study was conducted in apple orchards in 4 regions of France during the 2016 and 2017 treatment seasons. Workers’ external contamination and their determinants were assessed over 156 working days corresponding to 30 treatment days, 68 re-entry days and 58 harvesting days. We measured pesticide dermal contamination during each task and made detailed observations of work characteristics throughout the day. Captan and dithianon were used as markers of exposure.

Results

The median dermal contamination per day was 5.50 mg of captan and 3.33 mg of dithianon for operators, 24.39 mg of captan and 1.84 mg of dithianon for re-entry workers, and 5.82 mg of captan and 0.74 mg of dithianon for harvesters. Thus, workers performing re-entry tasks, especially thinning and anti-hail net opening, presented higher contamination, either equal to or higher than in operators. For these last ones, mixing/loading and equipment cleaning were the most contaminating tasks. Most of the contamination was observed on workers’ hands in all tasks, except for net-opening in which their heads accounted for the most daily contamination.

Conclusions

This study highlights the importance of taking indirect exposures into account during re-entry work in apple growing.

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.

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.

Determination of pesticide dermal transfer to operators and agricultural workers through contact with sprayed hard surfaces

BACKGROUND

In the present study, the rate of dermal transfer of pesticides to agricultural workers occurring via contact with sprayed hard surfaces was investigated. Cotton gloves were used as dosimeters to collect residues from hard surfaces contaminated by pesticides in greenhouses. Dosimeters, either dry or moistened, were in contact with wood, metal and plastic surfaces that had previously been sprayed. The experimental approach applied mimicked typical hand contact. Moistened cotton gloves were used to simulate hand moisture from dew/condensation or rainfall. The effect of total duration of contact on the final hand exposure via transfer was investigated.

RESULTS

The higher duration contact tested (50 s) resulted in higher transfer rates for metal and plastic surfaces; no such effect was noted in the case of the wood surface. The pesticide amount transferred from the metal and plastic surfaces to wet gloves was greater than that transferred to dry gloves. Such a trend was not observed for the wood surface. Transfer rates varied from 0.46 to 77.62% and from 0.17 to 16.90% for wet and dry samples, respectively.

CONCLUSION

The current study has generated new data to quantify the proportion of pesticide deposits dislodged from three different non-crop surfaces when in contact with dry or wet gloves. © 2018 Crown copyright. Pest Management Science © 2018 Society of Chemical Industry.

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

During pesticide application, operators are exposed to chemical products. Dermal exposure has been reported as the principal means of exposure for growers. In the present work, potential dermal exposure (PDE) has been assessed when using new low-cost equipment (a knapsack with a vertical spray boom) and compared to a hand-held spray lance, which is the equipment most widely used by growers in greenhouses. Two sprayers were used, a hand-held spray lance with four twin flat-fan nozzles and a knapsack fitted out with a vertical spray boom containing 3 pairs of twin flat-fan nozzles. Three applications were carried out and compared, one with the spray lance walking backwards (the reference application), and two with the spray boom - the first stopping at the turns and the second with no stopping. The patch method (19 position on the body) and tartrazine (the tracer) were used to assess de PDE. Each application tested was replicated three times. The results show that the knapsack with the vertical boom should not be used walking continuously along the greenhouse rows because the total PDE (1637.12mL 1000L^-1) is greater than in the rest of the configurations tested. If the operator stops at the turns for a few seconds, allowing the previously sprayed droplet cloud to dissipate, the level of exposure decreases significantly (324.63mL 1000L^-1), providing similar results to the reference application with the spray lance walking backwards (292.25mL 1000L^-1).