Cumulative probabilistic risk assessment of triazole pesticides in Belgium from 2011-2014.

Pesticide residues in food can lead to harmful toxic effects when exposed. Some of these compounds have a common Mode of Action and thus elicit a similar biological response. This paper considers the triazoles, a class of widely used fungicides exhibiting the same short-term (acute) and long-term (chronic) response in humans. We examined Belgian pesticide residue data from 2011-2014 and coupled these with the results of the Belgian food consumption survey of 2004. Cumulative probabilistic risk assessment was done using the Monte Carlo Risk Assessment 8.0 web application. The European Food Safety Authority (EFSA) published a guidance document that proposes both optimistic and pessimistic scenarios for dietary exposure assessment. Other than those two, a third, more balanced, scenario was simulated and showed an exposure right in between the EFSA scenarios. In the optimistic scenario, the foods with the highest measured residues in the residue data contributed the most to the total health risk. In the balanced and pessimistic scenarios, the highest contribution to the total health risk was made by active ingredients with a high sampling rate and/or a high consumption rate. No significant trends were observed in the health risk through 2011 to 2014, and the exposure distribution showed no health risks for the extreme consumers, with one exception in 2012.

Selecting mixtures on the basis of dietary exposure and hazard data: application to pesticide exposure in the European population in relation to steatosis.

Populations are exposed to mixtures of pesticides through their diet on a daily basis. The question of which substances should be assessed together remains a major challenge due to the complexity of the mixtures. In addition, the associated risk is difficult to characterise. The EuroMix project (European Test and Risk Assessment Strategies for Mixtures) has developed a strategy for mixture risk assessment. In particular, it has proposed a methodology that combines exposures and hazard information to identify relevant mixtures of chemicals belonging to any cumulative assessment group (CAG) to which the European population is exposed via food. For the purposes of this study, food consumption and pesticide residue data in food and drinking water were obtained from national surveys in nine European countries. Mixtures of pesticides were identified by a sparse non-negative matrix underestimation (SNMU) applied to the specific liver steatosis effect in children from 11 to 15 years of age, and in adults from 18 to 64 years of age in nine European countries. Exposures and mixtures of 144 pesticides were evaluated through four different scenarios: (1) chronic exposure with a merged concentration dataset in the adult population, (2) chronic exposure with country-specific concentration datasets in the adult population, (3) acute exposure with a merged concentration dataset in the adult population, and (4) chronic exposure with a merged concentration dataset in the paediatric population. The relative potency factors of each substance were calculated to express their potency relative to flusilazole, which was chosen as the reference compound. The selection of mixtures and the evaluation of exposures for each country were carried out using the Monte Carlo Risk Assessment (MCRA) software. Concerning chronic exposure, one mixture explained the largest proportion of the total variance for each country, while in acute exposure, several mixtures were often involved. The results showed that there were 15 main pesticides in the mixtures, with a high contribution of imazalil and dithiocarbamate. Since the concentrations provided by the different countries were merged in the scenario using merged concentration data, differences between countries result from differences in food consumption behaviours. These results support the approach that using merged concentration data to estimate exposures in Europe seems to be realistic, as foods are traded across European borders. The originality of the proposed approach was to start from a CAG and to integrate information from combined exposures to identify a refined list of mixtures with fewer components. As this approach was sensitive to the input data and required significant resources, efforts should continue regarding data collection and harmonisation among the different aspects within the pesticides regulatory framework, and to develop methods to group substances and mixtures to characterise the risk.

Formulation approaches to reduce post-application pesticide volatilisation from glass surfaces.

Volatilisation is one of the main pathways for pesticide emission to the atmosphere. While formulation strategies and adjuvants are known to affect the fate of active ingredient, no general volatilisation reducing guidelines exist for formulation purposes. Moreover, as limited information on formulation effects is available, current pesticide fate models lack parameters characterising reduction of active ingredient volatilisation. The objective of this study was to investigate the volatilisation reducing potential of formulation types and adjuvants, and to propose an effective vapour pressure for pesticide fate modelling. Several formulations of fenpropimorph, pyrimethanil and tebuconazole were produced and tested in a wind tunnel to evaluate the effect of formulation on active ingredient volatilisation. Produced emulsifiable concentrates with high volatile solvents did not offer any reduction in volatilisation, while the low volatile solvent reduced the volatilisation of pyrimethanil and fenpropimorph with 79.2 and 52.9%, respectively. The microemulsion reduced the volatilisation of fenpropimorph, pyrimethanil and tebuconazole with 57.6, 57.8 and 49.8%, respectively. High surfactant-active ingredient ratios (100:1) reduced the volatilisation of applied amount of pyrimethanil with 50%, on average. The effective vapour pressure of pyrimethanil formulated as a commercial available suspension concentrate was reduced by 33.8%. The commercial available emulsifiable concentrate did not reduce volatilisation of fenpropimorph. Effective vapour pressures of formulated fenpropimorph and pyrimethanil were determined and showed a high correlation with the amount volatilised within 48h. The saturated vapour pressure is useful when comparing the volatility of active ingredients, but effective vapour pressures are more appropriate to be used in pesticide fate models.

Multi-residue determination and ecological risk assessment of pesticides in the lakes of Rwanda.

BACKGROUND: To boost agricultural productivity for both domestic and export purposes, agricultural inputs such as pesticides are being promoted in Rwanda. Even though the use of pesticides is important for agriculture, their residues eventually end up in different environmental compartments and may negatively affect the environment. The purpose of this study was to determine the level of knowledge and awareness of the smallholder farmers towards the use of pesticides in Rwanda and to evaluate the ecological risks of pesticides in the surface water and in the vertical profile of Lake Kivu. RESULTS: Based on the collected data, a method to monitor 33 currently used pesticides was developed. No contamination of the lower water layer was found, indicating that the groundwater that flows into Lake Kivu has not been polluted. Of the pesticides in the surface water, malathion exceeded the risk thresholds and posed a risk towards arthropods. CONCLUSION: The results of this study show that there is a lack of farmer's awareness towards the hazards of pesticides when working with these compounds. Farmers in Rwanda are in need of specialised stewardship for pesticide application training and guiding services. Surface water has been contaminated with malathion, metalaxyl and carbendazim which were the most used pesticides by the farmers in the environment.

Pesticide residues in drinking water and associated risk to consumers in Ethiopia.

Access to safe and reliable drinking water is vital for a healthy population. However, surface water may be contaminated with pesticides because of the nearby agricultural areas as well as from household application. Water samples were collected from water sources in Jimma zone and Addis Ababa, Ethiopia. The extraction and clean up of the samples were undertaken using liquid-solid and liquid-liquid methods. Human exposure was assessed by calculating the estimated daily intake (EDI) of pesticides in water and compared with the acceptable daily intake (ADI) and the acute reference dose (ARfD). The mean concentrations of 2,4-D, malathion, diazinon and fenpropimorph were 1.59-13.90 µg/l and 0.11-138 µg/l in Jimma and Addis Ababa water sources, respectively. The residue level of some of the pesticides were above the European drinking water guide line values, which is an indication of an illegal use of pesticides in the study areas. Concerning human health risk estimation, there was no acute risk (EDI < ARfD). However, chronic risks to human health were observed from exposure to diazinon and fenpropimorph (EDI > ADI) for Jimma and Addis Ababa populations, respectively. A comprehensive monitoring is required to reduce the level of pesticide residues in the water and to minimize particularly the long term human health risks.

Influence of adjuvants on the dissipation of fenpropimorph, pyrimethanil, chlorpyrifos and lindane on the solid/gas interface.

The use of pesticides is an integral part of modern agriculture and contributes to the productivity and the quality of the cultivated crop. However, use of pesticides imposes a huge burden on the environment. Volatilisation of pesticides contaminates the environment, affects nearby crops, bystanders and residents but research to mitigate this environmental contamination remains scarce. In this study, the use of adjuvants to reduce the volatilisation and mitigate the environmental contamination was investigated. Dissipation of fenpropimorph, pyrimethanil, chlorpyrifos-ethyl and lindane as pure active ingredient, formulated by different adjuvants and in a commercial formulation were studied. An empirical model assuming exponential decay of the volatilisation rate was used to calculate the volatilisation. In 48 h, up to 90% of the pure fenpropimorph and lindane volatilised. Addition of adjuvants was shown to reduce the volatilisation of pesticides by up to 80%. Commercial formulation was able to reduce the volatilisation of pyrimethanil but the formulation of fenpropimorph had no effect on its volatilisation.