| Abstract |
The risk of a person or group of persons due to their exposure to a potentially toxic compound is a function of the toxicological properties of the compound and the level of exposure. The levels of exposure of operators, workers and bystanders, during pesticide application is a very important mean to determine the risk for the aforementioned exposed populations. In the frame of this PhD thesis for the determination of the pesticide operator exposure levels field trials were carried out according to a defined protocol and all parameters were recorded. The aim of the measurements was the determination of: a) the potential dermal exposure levels (PDE) representing the amount of the pesticide active substance (a.s.) that lands on the operator b) the actual dermal exposure levels (ADE) representing the amount that penetrates the protective or the working clothing and reaches the operator’s skin c) the potential and actual hand exposure and c) the determination of inhalation exposure.
To date the determination of operator exposure levels to pesticides is mostly carried out computationally by predictive models which have been developed for cropping practices and conditions of north European countries that are generally non comparable to the ones of Greece and the southern zone in general. Operator exposure studies as well as studies of similar objectives that have been carried out in the past by Benaki Phytopathological Institute show that in many cases the results derived from field experiments are significantly different from the respective ones of the predictive models, whenever the latter are applicable. However in all cases the experimental studies of this kind are limited at “pilot scale” which is a fact stressing the need for further investigation and studies on this theme.
This PhD thesis was structured in 3 main sections:
Section I: Determination of operator exposure levels during insecticide bait application to olive trees.
Section II: Determination of operator exposure levels during fungicide application to vineyards.
Section III: Determination of operator exposure levels during fungicide application to greenhouse peppers with a new type of spraying equipment.
All three application scenarios are representative for Greece and apply to a high percentage to the area of cultivated land, the geographical distribution of it and the usual farming practices (olive groves, vineyards, and greenhouses). Especially the bait application is a safe and an environmental friendly way of pesticide application due to the fact that only a small part of the tree canopy is sprayed.
In the experimental part, in all three sections, the methodology used was the “whole body dosimetry” based on the respective OECD protocols. At all three sections two protective coverall types were studied i.e. a 50/50 % cotton/polyester treated with water repellent finish attached at the nano level to the fibers and a 100% cotton coverall.
The laboratory analyses were conducted with fully validated methods also being part of this work. Finally a literature review was carried out concerning the thematic objectives of this PhD thesis. In the frame of this review the theoretical part was compiled where the current predictive models for operator exposure are presented and discussed. These models are: a) The British model (UK POEM) b) the German Model (BBA Model) c) EUROPOEM model d) the Dutch model e) other models ((Dutch greenhouse model, PHED, Seed Tropex, AHEAD, Southern European greenhouse model etc) f) newly developed models which are the BROWSE model and the EFSA model (EFSA calculator).
For each of the three sections of this work the respective experimental results (i.e. operator exposure levels from field trials) were compared to the exposure estimations derived from the German model and the EFSA calculator since those two models were identified to be the most relevant ones considering the respective application scenarios studied. The comparisons showed over or underestimation of the exposure by the models at certain cases. Regarding Section I trials the experimental results were lower than the estimation of the German model for the “trunk & legs” part when the 75th percentile and the use of personal protection equipment were considered being in accordance with the specific application scenario characteristics. Using the EFSA model only in one case, i.e the ““trunk & legs” the experimental exposure levels and the model derived ones were comparable. At the bait application scenario both types of coveralls provided satisfactory levels of protection, as derived from the respective potential and actual exposure levels measured, and therefore can be regarded as appropriate personal protection equipment for this scenario. Finally from the conduction of comparison trials addressing the parameter of application duration no evidence of linear correlation between exposure levels and duration was found for the studied scenario.
In the fungicide application scenario to vineyards (Section II) the results showed that the operator’s body part mostly exposed to spray cloud is the “trunk and legs” part (89% of the total PDE) followed by potential hand exposure (<10% of total PDE). The experimental results of potential and actual dermal exposure in most case-by-case comparisons were differentfrom those predicted by the German Model which is an observation that stresses the need for further updating and refinement of the German Model as regards the aforementioned scenario. It was also concluded that the derived experimental datasets of exposure could be utilized as surrogate values for this purpose. Furthermore the comparison with the EFSA calculator showed underestimation of exposure by the model in the majority of cases (ranging between 69 and 94%). Regarding coverall performance also in the fungicide application trials, both types showed low penetration thus provided satisfactory degree of protection.
In the greenhouse application scenario of Section III with the new type of application equipment the results were in line with a high exposure application scenario. The comparison of the measured exposure levels with respective results from previous study of the Benaki Phytopathological Institute, regarding greenhouse applications using conventional spray gun, showed that the potential exposure levels were up to one order of magnitude higher than those of the spray gun study indicating no positive evidence of reduced exposure with the use of the new spraying tool.
Finally one more aspect addressing the contribution new knowledge through this PhD thesis was the development of fully validated analytical methods required for the analytical determination of the pesticides in personal protective equipment. Furthermore the respective experimental field protocol was developed, properly adjusted and applied accordingly in practice being concurrently in the frame and philosophy of the principles of Good Agricultural Practice (GAP) and the OECD protocols. This could undoubtedly be regarded as a useful contribution and a helpful testament for the conduction of further research studies in this thematic field in the future.
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Προσδιορισμός επιπέδων έκθεσης των ψεκαστών σε φυτοπροστατευτικά προϊόντα κατά την εφαρμογή τους σε αντιπροσωπευτικές για τη χώρα μας καλλιέργειες : Ανάπτυξη βάσης δεδομένων και αξιόπιστων μεθόδων πρόβλεψης επικινδυνότητας
