Input dynamics and fate in surface water of the herbicide metolachlor and of its highly mobile transformation product metolachlor

A large number of herbicide transformation products has been detected in surface waters and groundwaters of agricultural areas, often even in higher concentrations and more frequently than their parent compounds. However, their input dynamics and fate in surface waters are still rather poorly understood. This study compares the aquatic fate, concentration levels, and dynamics of the transformation product metolachlor ethanesulfonic acid (metolachlor ESA) and its parent compound metolachlor, an often-used corn herbicide. To this end, laboratory photolysis studies were combined with highly temporally resolved concentration measurements and lake mass balance modeling in the study area of Lake Greifensee (Switzerland). It is found that the two compounds show distinctly different concentration dynamics in the lake tributaries. Concentration-discharge relationships for metolachlor ESA in the main tributary showed a high baseflow concentration and increasing discharge dependence during harvest season, whereas baseflow concentrations of metolachlor were negligible and the discharge dependence was restricted to the period immediately following application. From this it was estimated that 70% of the yearly load of metolachlor ESA to the lake was due to groundwater recharge, whereas, for metolachlor, the bigger part of the load, 50-80%, stemmed from event-driven runoff. Lake mass balance modeling showed that the input dynamics of metolachlor and metolachlor ESA are reflected in their concentration dynamics in the lake's epilimnion and that both compounds show a similar fate in the epilimnion of Lake Greifensee during the summer months with half-lives on the order of 100-200 days, attributable to photolysis and another loss process of similar magnitude, potentially biodegradation. The behavior of metolachlor ESA can likely be generalized to other persistent and highly mobile transformation products. In the future, this distinctly different behavior of mobile pesticide transformation products should find a more appropriate reflection in exposure models used in chemical risk assessment and in pesticide risk management.     

烟草中酰胺类除草剂残留量的测定

研究了烟草中异丙甲草胺、敌草胺和双苯酰草胺残留量的同时多残留测定方法，使用乙酸乙酯和环己烷混合溶剂提取农药残留，水与有机溶剂液／液分配和弗罗里硅土柱层析净化，气相色谱法配氮磷检测器测定。异丙甲草胺、敌草胺和双苯酰草胺的平均回收率分别为90．0％、80．4％和84．8％，检出限均为0．02ug／g。结果令人满意。     

Pesticide residues in washing water of olive oil mills: effect on olive washing efficiency and decontamination proposal

BACKGROUND: Washing olives in the olive oil mill (a commonly used preliminary step to remove foreign materials and leaves) can help to remove pesticide residues, especially herbicides that are present in olives due to contamination either during application or as a consequence of contact with contaminated soil. The aim of the present work was the study of washing efficacy during washing cycles, i.e., from the beginning of the cycle until the water was changed. RESULTS: Four active ingredients, namely diuron, oxyfluorfen, terbuthylazine and endosulfan (α and β isomers) as well as the latter's degradation product endosulfan sulfate, were the most frequently found pesticides in raw olives after harvest. At the beginning of the washing cycle, diuron, terbuthylazine and oxyfluorfen residues were effectively removed from olives. However, progressive water contamination with pesticide residues decreased the efficiency of the washing step, specially for diuron and terbuthylazine residues. CONCLUSION: A decontamination method to enable water recycling in olive oil mills was proposed and optimized. It employed FeCl₃ as coagulant and active charcoal as adsorbent, and was effective in removing both suspended solids and pesticide residues. Copyright © 2008 Society of Chemical Industry     

食品中农药残留的膳食暴露与累积性暴露评估研究

农药残留超标是消费者比较关心的问题,关系到消费者身体健康与国际贸易.开展农药残留的膳食暴露评估对我国的食品质量安全控制有重要意义.本文就最大残留限量和日允许摄入量的关系,农药残留膳食暴露评估的模式和累积性暴露评估进行了阐述,并对我国农药残留的膳食暴露评估提出几点建议.     

除草剂异丙甲草胺特异性抗体制备及免疫检测方法的建立

为检测食品中的异丙甲草胺农药残留,降低其对人体可能造成的危害,本文建立了基于抗体的酶联免疫分析方法。首先以除草剂异丙甲草胺、3-巯基丙酸为原料合成半抗原,经由氢核磁共振和质谱方法鉴定后,通过碳二亚胺（EDC）法将半抗原与载体蛋白偶联制备异丙甲草胺人工抗原,免疫新西兰大白兔获取抗体,通过棋盘滴定确定抗原抗体最佳稀释倍数,ELISA反应的抗体稀释液为PBS（1% PEG 6000）,药物稀释液为PBS（10%甲醇）,在此基础上建立间接竞争ELISA标曲,其IC50为14.64 ng/mL,检测限（limit of detection,LOD）为0.8 ng/mL,线性检测范围IC20~IC80为1.51~141.92 ng/mL。与14种结构类似物进行交叉反应,交叉反应率低于3%。向环境水样中添加异丙甲草胺,回收率为86.60%~102.16%,变异系数（RSD）为7.05%~13.30%。此抗体灵敏度高特异性好,可用于食品和环境中异丙甲草胺的监测。     

Solar radiation, relative humidity, and soil water effects on metolachlor volatilization

Pesticide volatilization is a significant loss pathway that may have unintended consequences in nontarget environments. Field-scale pesticide volatilization involves the interaction of a number of complex variables. There is a need to acquire pesticide volatilization fluxes from a location where several of these variables can be held constant. Accordingly, soil properties, tillage practices, surface residue management, and pesticide formulations were held constant while fundamental information regarding metolachlor volatilization (a pre-emergent pesticide) was monitored over a five-year period as influenced by meteorological variables and soil water content. Metolachlor vapor concentrations were measured continuously for 120 h after each application using polyurethane foam plugs in a logarithmic profile above the soil surface. A flux gradient technique was used to compute volatilization fluxes from metolachlor concentration profiles and turbulent fluxes of heat and water vapor (as determined from eddy covariance measurements). Differences in meteorological conditions and surface soil water contents resulted in variability of the volatilization losses over the years studied. The peak volatilization losses for each year occurred during the first 24 h after application with a maximum flux rate in 2001 (1500 ng m(-2) s(-1)) associated with wet surface soil conditions combined with warm temperatures. The cumulative volatilization losses for the 120-hour period following metolachlor application varied over the years from 5 to 25% of the applied active ingredient, with approximately 87% of the losses occurring during the first 72 h. In all of the years studied, volatilization occurred diurnally and accounted for between 43 and 86% during the day and 14 and 57% during the night of the total measured loss. The results suggest that metolachlor volatilization is influenced by multiple factors involving meteorological, surface soil, and chemical factors.     

Assessment of dermal exposure to pesticide residues during re-entry

Currently, the determination of health risks to pesticide applicators from dermal exposure to these chemicals is assessed using either a concentrate of the compound or a relevant aqueous dilution. Neither of these conditions reflects a normal exposure of an individual when re-entering an area after pesticide application, that is, contact with dried residue of the diluted product on foliage. Methodology has therefore been developed to determine a relevant estimate of this potential dermal re-entry exposure from pesticide residues. Potential delivery platforms have been characterized for the transfer of pesticide residue to skin. Spin coating has been used to deposit uniform pesticide layers on to each platform. Five pesticides have been chosen to encompass a wide range of physicochemical properties: atrazine, 2,4-dichlorophenoxyacetic acid (2,4-D), chlorpyrifos, monocrotophos, and acetochlor. In vitro (Franz diffusion cell) experiments have been performed to monitor the transfer of these pesticides from the delivery platforms onto and through excised porcine skin. Parallel experiments were also conducted with aqueous pesticide dilutions for comparison, and a final in vivo measurement using ibuprofen (as a model compound) complemented the in vitro data. The results demonstrate that transfer of chemical residue onto and subsequently through the skin is dependent on the physical attributes of the residue formed. Thus, assessing dermal exposure to pesticides based on skin contact with either the chemical concentrate or a relevant aqueous dilution may incorrectly estimate the risk for re-entry scenarios.     

Assessment of the effects of farming and conservation programs on pesticide deposition in high plains wetlands

We examined pesticide contamination in sediments from depressional playa wetlands embedded in the three dominant land-use types in the western High Plains and Rainwater Basin of the United States including cropland, perennial grassland enrolled in conservation programs (e.g., Conservation Reserve Program [CRP]), and native grassland or reference condition. Two hundred and sixty four playas, selected from the three land-use types, were sampled from Nebraska and Colorado in the north to Texas and New Mexico in the south. Sediments were examined for most of the commonly used agricultural pesticides. Atrazine, acetochlor, metolachlor, and trifluralin were the most commonly detected pesticides in the northern High Plains and Rainwater Basin. Atrazine, metolachlor, trifluralin, and pendimethalin were the most commonly detected pesticides in the southern High Plains. The top 5-10% of playas contained herbicide concentrations that are high enough to pose a hazard for plants. However, insecticides and fungicides were rarely detected. Pesticide occurrence and concentrations were higher in wetlands surrounded by cropland as compared to native grassland and CRP perennial grasses. The CRP, which is the largest conservation program in the U.S., was protective and had lower pesticide concentrations compared to cropland.     

Occurrence and spatial and temporal distribution of pesticide residues in groundwater of major corn-growing areas of Greece (1996-1997)

During 1996-1997, residues of selected pesticides were monitored, at 3-month intervals, in 80 wells, including both irrigation and drinking water wells, distributed among the main corn-growing areas (Pieria, Thessaloniki, Serres, Kavala, and Evros) of Greece. Pesticide residues were found in 48% of the wells; however, in most cases residues were very low ranging from LOQs (quantification limits of the analytical methods) to <0.1 microg/L, while in 11% (nine wells) pesticide residues higher than 0.1 microg/L were present. Most of the latter wells were found in Evros and specificallythe Ardas Valley. The frequency of occurrence, in descending order, was atrazine > DEA > alachlor = metolachlor; however, the order of descending concentrations was atrazine > metolachlor > DEA > alachlor. The occurrence and the spatial and temporal distribution patterns of pesticide residues indicate that at the present the situation of groundwater quality is favorable throughout the corn-growing areas of Greece with the exception of the Ardas Valley.     

Pesticides on household surfaces may influence dietary intake of children

The physical and chemical environment influences children's exposures to pesticides in and around the home. Children's activities, which increase their potential for exposure especially during eating, have been captured in the Children's Dietary Intake Model (CDIM). In addition to the chemical exposure associated with the food itself, this model incorporates excess dietary exposures due to handling of food during consumption. To stochastically evaluate CDIM, distributions of measured, and in some cases estimated, model factors were determined from measurements of permethrin, chlorpyrifos, and diazinon derived from assembled databases and laboratory experiments. Using the distributions of these factors, Monte Carlo simulations were performed to obtain distributions of total dietary intake of pesticides. To target the sources of pesticide contamination that were influencing total dietary intake, each factor was evaluated. We found pesticide surface concentration to be highly influential. By excluding surface concentration, we were also able to determine the influence of the other factors based on the F-statistic. Transfer efficiencies, followed by pesticide residue in consumed foods and amount of food consumed, were the next most influential factors within the model. With these distributions for model inputs, CDIM has the potential to more accurately predict total dietary intake of a contaminant by a child.     

芒果果实中农药残留分布及慢性膳食摄入风险

为掌握常用农药在芒果果实中的残留分布情况及其对慢性膳食摄入风险的贡献大小.采用气相色谱和超高效液相色谱-串联质谱法测定样品中42个常用农药残留.采用点评估方法计算检出农药对儿童和成人的慢性膳食摄入风险的贡献份额,采用相对效能因子法计算农药的累积风险.44.1％的全果样品和35.5％的果肉样品中检出农药残留.吡虫啉在全果...     

果蔬加工过程农药残留行为研究及加工因子在风险评估中的应用

食品安全问题一直是社会关注的焦点,而果蔬中农药残留是影响食品安全的重要因素之一。果蔬产品大部分需要经过加工处理,残留在果蔬中的农药在加工过程中受到不同程度的影响,如清洗、去皮等加工对于果 蔬表面的非内吸性农药有显著的去除效果,而热处理过程对某些农药存在蓄积作用,在某些情况下也会加快分解或形成有毒的代谢产物。随着加工工艺水平不断提升,新型的加工方式在果蔬加工过程中应用越来越广泛,对农药残留影响也越发复杂。因此,本文对果蔬加工过程中农药残留行为影响进行系统综述,并总结农药残留加工因子在膳食暴露评估中的应用,以期为农药残留进行精准膳食风险评估和农药合理使用提供依据。     

Assessing exposure to transformation products of soil-applied organic contaminants in surface water: comparison of model predictions and field data

Transformation products (TPs) of chemicals released to soil, for example, pesticides, are regularly detected in surface and groundwater with some TPs even dominating observed pesticide levels. Given the large number of TPs potentially formed in the environment, straightforward prioritization methods based on available data and simple, evaluative models are required to identify TPs with a high aquatic exposure potential. While different such methods exist, none of them has so far been systematically evaluated against field data. Using a dynamic multimedia, multispecies model for TP prioritization, we compared the predicted relative surface water exposure potential of pesticides and their TPs with experimental data for 16 pesticides and 46 TPs measured in a small river draining a Swiss agricultural catchment. Twenty TPs were determined quantitatively using solid-phase extraction liquid chromatography mass spectrometry (SPE-LC-MS/MS), whereas the remaining 26 TPs could only be detected qualitatively because of the lack of analytical reference standards. Accordingly, the two sets of TPs were used for quantitative and qualitative model evaluation, respectively. Quantitative comparison of predicted with measured surface water exposure ratios for 20 pairs of TPs and parent pesticides indicated agreement within a factor of 10, except for chloridazon-desphenyl and chloridazon-methyl-desphenyl. The latter two TPs were found to be present in elevated concentrations during baseflow conditions and in groundwater samples across Switzerland, pointing toward high concentrations in exfiltrating groundwater. A simple leaching relationship was shown to qualitatively agree with the observed baseflow concentrations and to thus be useful in identifying TPs for which the simple prioritization model might underestimate actual surface water concentrations. Application of the model to the 26 qualitatively analyzed TPs showed that most of those TPs categorized as exhibiting a high aquatic exposure potential could be confirmed to be present in the majority of water samples investigated. On the basis of these results, we propose a generally applicable, model-based approach to identify those TPs of soil-applied organic contaminants that exhibit a high aquatic exposure potential to prioritize them for higher-tier, experimental investigations.     

Exposure assessment of the Belgian population to pesticide residues through fruit and vegetable consumption

Exposure of the Belgian consumer to pesticide residues from the consumption of fruit and vegetables was determined based on data collected in the Belgian food consumption survey performed by the Scientific Institute for Public Health and data from the Belgian Federal Agency for the Safety of the Food Chain 2005 monitoring programme. A first screening of pesticide residue exposure was performed by a deterministic approach. For most pesticide residues studied, the exposure was 100 times lower than the acceptable daily intake (ADI). However, for a high consumer (97.5th percentile of consumption) the intake could reach 23% of the ADI for imazalil, 15% for chlorpropham, 14% for the dithiocarbamates, 10% for dimethoate and lambda-cyhalothrin, and 9% for chlorpyriphos. Nevertheless, probabilistic exposure assessment performed on these pesticides in a second phase of the study indicated that, except for chlorpropham, the probability to exceed the ADI is much lower than 0.1%.     

Exposure assessment of the Belgian population to pesticide residues through fruit and vegetable consumption

Exposure of the Belgian consumer to pesticide residues from the consumption of fruit and vegetables was determined based on data collected in the Belgian food consumption survey performed by the Scientific Institute for Public Health and data from the Belgian Federal Agency for the Safety of the Food Chain 2005 monitoring programme. A first screening of pesticide residue exposure was performed by a deterministic approach. For most pesticide residues studied, the exposure was 100 times lower than the acceptable daily intake (ADI). However, for a high consumer (97.5th percentile of consumption) the intake could reach 23% of the ADI for imazalil, 15% for chlorpropham, 14% for the dithiocarbamates, 10% for dimethoate and lambda-cyhalothrin, and 9% for chlorpyriphos. Nevertheless, probabilistic exposure assessment performed on these pesticides in a second phase of the study indicated that, except for chlorpropham, the probability to exceed the ADI is much lower than 0.1%.     

A new model for the prediction of agricultural operator exposure during professional application of plant protection products in outdoor crops

A new predictive model for the estimation of agricultural operator exposure has been developed on the basis of new exposure data to improve the current agricultural operator exposure and risk assessment in the EU. The new operator exposure model represents current application techniques and practices in EU Member States (MS) and is applicable for national or zonal authorisation of plant protection products as well as for approval of active substances in plant protection products (PPP) supporting a stepwise risk assessment. 34 unpublished exposure studies conducted between 1994 and 2009 were evaluated for the new model. To ensure a very high quality of data the studies had to meet a set of quality criteria, e.g. GLP conformity or compliance with OECD guidance. Exposure data and supplementary information on the trials were used for a statistical analysis of exposure factors. The statistical analyses resulted in six validated models for typical outdoor scenarios of pesticide mixing/loading and application. As a major factor contributing to the exposure of operators, the amount of active substance used per day was identified. Other parameters such as formulation type, droplet size, presence of a cabin or density of the canopy were selected as factors for sub-scenarios. For two scenarios the corresponding datasets were too small to identify reliable exposure factors; instead the relevant percentiles of the exposure distribution were used. The whole project report on the development of the new model (including the underlying study data) and the corresponding exposure calculators will be published at the BfR website (http://www.bfr.bund.de) after confirmation of the model by EU MS.     

Swift probabilistic risk assessment model of chemical hazards in food by tiered approach: A case study of pesticide residues in packaged red pepper powder

Development of a swift probabilistic risk assessment (sPRA) model is needed to obtain information on exposure to food hazards before performing complex full-scale risk assessment. A sPRA model was developed using a tiered approach, which uses qualitative information, quantitative analysis of focused hazards, and a Monte Carlo simulation. A case study was conducted on residual pesticides in red pepper powder using sPRA model. Of a wide range of pesticides, chlorpyrifos and cypermethrin were selected for sPRA modeling. As a result of the sPRA model simulation, the estimated dietary exposure to pesticide residue from the consumption of red pepper powder was below 0.04% of the acceptable daily intake (ADI) for the 95^th percentile exposure. Risk of dietary exposure to hazards was quantitatively estimated by the sPRA model developed, and the risk of residual pesticide in red pepper powder in Korea was found to be very low.     

Reduction of pesticides residues on okra fruits by different processing treatments

For the first time, the effect of washing, water boiling, chemical boiling, steaming and cooking treatments on the reduction of residues of indoxacarb, fenarimol, acetamiprid and chlorfenapyr in okra fruits was investigated. Residues were analyzed using quick, easy, cheap, effective, rugged, and safe (QuEChERS) method combined with liquid chromatography tandem-mass spectrometry (LC–MS/MS). Our results show that some treatments could significantly decrease pesticide residues. The reduction of residues by washing treatment was not correlated to water solubility: Chlorfenapyr (non-systemic pesticide) was decreased by 90 % and acetamiprid (systemic pesticide) was removed by 48 %. Therefore, we suggest that pesticide residues were washed off by removing the loosely attached pesticides on the okra fruit surface. The time of exposure in both boiling and steaming treatments has no significant effect on reduction of pesticides residues. Additionally, cooking after the washing and boiling treatments reduced the pesticides residues. In particular, acetamiprid was reduced after the cooking treatment to 90 %.     

食品工厂中杀虫剂使用与管理

<正> 食品安全问题日益成为食品工厂所关心的重点,严格的安全体系认证、过敏原控制、外来物的控制以及综合虫害管理(IPM)等等都是食品工厂面临的现实挑战。其中综合虫害管理(IPM)摒弃了以往"单纯的害虫个体杀灭"的概念,提出通过物理、管理、设施完善等多种方法,将虫害群体减少至不对食品和人员构成威胁的某临界点,而不是过分依赖和不恰当地使用杀虫剂。因为杀虫剂所带来的食品安全及人身安全问题并不亚于虫害本身带来的问题,甚至有过之而无不及。因此,IPM 使用杀虫剂的态度是"有条件的使用,科学化的管理"。如何对杀虫剂加以科学的使用和管理也因此成为了食品工厂管理人员所关心的焦点。     

Evaluation of pesticide residues in fruits and vegetables from Algeria

ABSTRACT

A total of 160 samples of 13 types of fresh fruits and vegetables from domestic production and import were analysed to detect the presence of pesticide residues. Analysis was performed by multi-residual extraction followed by gas chromatography–mass spectrometry. In 42.5% of the tested samples, no residues were found and 12.5% of samples contained pesticide residues above maximum residue limits. Risk assessment for long-term exposure was done for all pesticides detected in this study. Except chlorpyrifos and lambda-cyhalothrin, exposure to pesticides from vegetables and fruits was below 1% of the acceptable daily intake. Short-term exposure assessment revealed that in seven pesticide/commodity combinations, including three pesticides (chlorpyrifos, deltamethrin and lambda-cyhalothrin), the acute reference dose had been exceeded.