Computer modelling as a tool for the exposure assessment of operators using faulty agricultural pesticide spraying equipment.

BACKGROUND: Faulty but still operating agricultural pesticide sprayers may pose an unacceptable health risk for operators. The computerized models designed to calculate exposure and risk for pesticide sprayers used as an aid in the evaluation and further authorisation of plant protection products may be applied also to assess a health risk for operators when faulty sprayers are used. OBJECTIVE: To evaluate the impact of different exposure scenarios on the health risk for the operators using faulty agricultural spraying equipment by means of computer modelling. MATERIAL AND METHODS: The exposure modelling was performed for 15 pesticides (5 insecticides, 7 fungicides and 3 herbicides). The critical parameter, i.e. toxicological end-point, on which the risk assessment was based was the no observable adverse effect level (NOAEL). This enabled risk to be estimated under various exposure conditions such as pesticide concentration in the plant protection product and type of the sprayed crop as well as the number of treatments. Computer modelling was based on the UK POEM model including determination of the acceptable operator exposure level (AOEL). Thus the degree of operator exposure could be defined during pesticide treatment whether or not personal protection equipment had been employed by individuals. Data used for computer modelling was obtained from simulated, pesticide substitute treatments using variously damaged knapsack sprayers. These substitute preparations consisted of markers that allowed computer simulations to be made, analogous to real-life exposure situations, in a dose dependent fashion. Exposures were estimated according to operator dosimetry exposure under 'field' conditions for low level, medium and high target field crops. RESULTS: The exposure modelling in the high target field crops demonstrated exceedance of the AOEL in all simulated treatment cases (100%) using damaged sprayers irrespective of the type of damage or if individual protective measures had been adopted or not. For low level and medium field crops exceedances ranged between 40 - 80% cases. CONCLUSIONS: The computer modelling may be considered as an practical tool for the hazard assessment when the faulty agricultural sprayers are used. It also may be applied for programming the quality checks and maintenance systems of this equipment.

Low-drift nozzles vs. standard nozzles for pesticide application in the biological efficacy trials of pesticides in apple pest and disease control.

The coarse spray air-induction nozzles have documented pesticide drift reducing potential and hence pose lower risk of environmental pollution than the standard fine spray hollow cone nozzles. However, it is questioned that use of the low-drift nozzles might not provide as effective crop protection as the standard nozzles. The objective of work was to assess the pest and disease control efficacy as affected by spray volume rate and nozzle type. The experiment was carried out in apple orchard, cv Jonagold/M26. The evaluated treatments were combinations of three spray volume rates: 250, 500 and 750lha-1, and two types of nozzles: hollow cone nozzles generating very fine spray, and flat fan air induction nozzles producing coarse droplets. The biological performance of treatments was determined based on severity of diseases: apple scab (Venturia inaequalis), powdery mildew (Podosphaera leucotricha) and bull's eye rot (Pezicula spp.), as well as population or damage caused by pests: green apple aphid (Aphis pomi), rosy apple aphid (Dysaphis plantaginea Pass.), woolly apple aphid (Eriosoma lanigerum), apple rust mite (Aculus schlechtendali) and apple blossom weevil (Anthonomus pomorum L.). In general apple scab was equally controlled by all treatments. Only in the years of high infection pressure efficacy of powdery mildew control was better for fine spray nozzles and high volume rates. Green and rosy apple aphids were better controlled with higher volume rates, though significance of the advantage over the lower rates was occasional. No effect of spray quality on efficacy of aphid and mite control was found for any spray volume rate. Better control of apple blossom weevil and woolly apple aphid was achieved with the high spray volume rate providing heavy coverage to the point of run-off. The air induction nozzles having drift reducing potential are biologically efficacious alternative to conventional hollow cone nozzles.

Environmentally Optimised Sprayer (EOS)--A software application for comprehensive assessment of environmental safety features of sprayers.

Despite technological progress in pesticide application equipment, chemical crop protection continues to contribute to environmental pollution. Water is at risk of contamination with pesticides from point and diffuse sources and could be reduced to a great extent with a better sprayer design. The sprayer manufacturers and pesticide applicators need to take more responsibility for the prevention of water pollution and therefore they have to make environmentally responsible decisions at different stages, from designing to servicing sprayers. The objective of the presented work was to develop an interactive application that would support decisions made by sprayer manufacturers during the production process, and by pesticide applicators when selecting and operating the sprayers. The EOS (Environmentally Optimised Sprayer) is an application evaluating the risk mitigation potential of sprayers based on their technological features, within five risk areas, representing sources of pollution: (i) Inside Contamination; (ii) Outside Contamination; (iii) Filling; (iv) Spray Loss & Drift; (v) Remnants. The evaluator completes the EOS questionnaire by checking for the technical solutions identified in the evaluated sprayer and the result reflects the sprayer quality in terms of potential environmental risk mitigation. The EOS tool also proved its awareness raising facility and educative value when used during training activities and university courses.