Exposure and risk profiles for a safe pesticide use in agriculture

BACKGROUND: Variability of climatic and working conditions in the open field and the use of complex mixtures of pesticides make biological and environmental monitoring in agriculture hardly feasible. The aim is to produce reliable and user-friendly risk assessment tools tailored for small and medium size enterprises where performing measures is too complicated. This target can be reached through a combination of environmental monitoring, biological monitoring and computational modelling. AIM OF STUDY: To recognize variables which significantly influence exposure to pesticides in agriculture, and to propose simple and reliable methods for risk assessment. METHODS: Through an extensive review of the published literature we identified the main work phases of pesticide application in agriculture, as well as factors reducing exposure. Then we analysed the main variables affecting exposure intensity and through field studies and professional judgement rank them and gave scores. These scores were inserted into a simple algorithm. At the same time we performed risk assessment through environmental exposure and biological monitoring in a pilot study on 24 agricultural workers applying herbicides to rice and corn. RESULTS: Mixing and loading, pesticide application, cleanup and maintenance are the main phases in field pesticide use. Weather conditions, duration of operations, number of loadings, concentration of active principle in the mixture, size of the tank, size of the farm, are some of the main variables influencing exposure. The reducing factors were identified as farmers’s training and experience, proper use of PPDs, and the condition of machineries. In our pilot study, most of the workers applying pesticides were well below the Acceptable Operator Exposure Level (AOEL). Our study estimated workers’ median levels of whole-body overclothing exposure to spray-applied propanil as 0.032 (0.01-1.24) ppm. Measurements above and below clothing show that the barrier efficiency of working clothes is approx. 50%. 24-hour post-application urine excretion of the main metabolite of propanil, 3,4-dichloroaniline is approximately 0.3 ppm of applied propanil. There was a significant positive correlation between on-skin and on-clothes levels of exposure, as well as between the exposure on skin and levels of pesticides in the urine of the workers. CONCLUSIONS: Results of our pilot study indicate that the process of risk assessment in the field could be made much simpler with the use of “exposure and risk profiles”. Through field studies on larger samples of workers it will be possible to generate provisional Biological Exposure Limits, which will allow risk assessment only through biological monitoring (24-hour urine).