Determination of residues of endosulfan in human blood by a negative ion chemical ionization gas chromatographic/mass spectrometric method: impact of long-term aerial spray exposure

A new and sensitive analytical method using negative ion chemical ionization gas chromatography/mass spectrometry in selective ion monitoring (SIM) mode has been developed for the determination of residues of endosulfan in the human blood. The residues of endosulfan are extracted from whole blood samples without separating the serum by the addition of 60% sulfuric acid at 10 degrees C followed by partition with hexane + acetone (9 + 1 by volume). The total endosulfan is quantified as the sum of alpha-endosulfan, beta-endosulfan and endosulfan sulfate in SIM mode. The mass-fragment ions used for this purpose that are monitored for in SIM mode include endosulfan diol: 95, 169, 214, 313, alpha-endosulfan: 99, 242, 270, 406, beta-endosulfan: 99, 242, 270, 406, and endosulfan sulfate: 97, 353, 386. Recovery experiments were conducted at the concentration range 1.0-100 pg ml(-1). Results showed 112-98% recovery of total endosulfan from the whole blood samples. The relative standard deviation was 1.49-2.68%. The method was found to be highly sensitive in quantifying endosulfan residues down to the 0.1 pg ml(-1) level. Conversion of endosulfan to endosulfan diol was found to be less than 0.1% under the conditions used. The results were compared with published data. The applications of the analytical method for the determination of endosulfan residues in real samples was tested by analyzing 106 human blood samples collected from a population living in Padre village, Kasargode District, Kerala, India, where aerial spraying of endosulfan has been a common agricultural practice over the years. The results showed that none of the blood samples contained residues of endosulfan (alpha-endosulfan 4 beta-endosulfan + endosulfan sulfate) or endosulfan diol. The results were confirmed by the detection of the appropriate amounts in a number of these samples which had subsequently been spiked with endosulfan.     

Behaviour of endosulfan residues in peppers,cucumbers and cherry tomatoes grown in greenhouse: evaluation by decline curves

Decline of endosulfan residues in pepper, cucumber and cherry tomatoes grown in greenhouses, and the corresponding statistical parameters, were evaluated assessing the formal approaches proposed by Timme, Frehse and Laska to study the behaviour of pesticide residues in crops. In all cases, the first-order reaction function was confirmed to describe the behaviour of endosulfan residues, but functions that best fit the experimental data were first-order for cucumber, RF-first-order for pepper and RF-1·5th-order for tomato. Half-life periods of endosulfan residues determined from the first-order function were 11·1(±1·3) days (cucumber), 15·2(±3·3) days (pepper) and 20·1(±6·6) days (tomato), whereas the values obtained from the optimal functions were close to 10 days for the three plantations. © 1997 SCI     

Accumulation of endosulfan residues in fish and their predators after aerial spraying for the control of tsetse fly in Botswana

Residues of endosulfan insecticide (α- and β-isomers, and ‘endosulfan sulphate’) in fish and their predators were measured during and after operations to control tsetse fly in the Okavango Delta, Botswana. Six ultra-low-volume doses of endosulfan 35% e.c. (6–12 g a.i. ha^?1) were applied from the air in a period of 12 weeks over 2500 km². The concentration of residues found in living fish was up to 0.19 mg kg^?1 wet wt in caudal muscle, and usually < 0.8 mg kg^?1 wet wt in pooled viscera (maximum 2.8 mg kg^?1). These values returned to near-normal within 3 months after cessation of spraying, but residues were still detectable after 12 months. By comparison, fish killed by spraying contained a maximum residue level (whole-body) of 1.5 mg kg^?1 wet wt. The residue level in fish was approximately proportional to their fat content. Lean fish were more susceptible to poisoning than fat fish. The proportion of the ‘endosulfan sulphate’ metabolite in fish increased at least six times with respect to the parent isomers (α+β) during the period of spraying, but more advanced stages of metabolic breakdown were not monitored. Residue levels in fish predators (fish-eating birds and crocodiles) were similar to those in their prey, and the risk to them was consequently low.     

给农业插上科技的翅膀：植保无人机低容量喷雾技术助力农药减施增效

十三五期间以植保无人机低容量施药技术为代表的现代航空植保产业发展迅速。科研协作研究与大量田间试验示范表明,采用植保无人机施药技术能够提高靶标作物上药液沉积量并减少农药流失,实现精准减量施药;同时能够解决地面机具无法作业时的病虫害防治问题。航空植保技术实现了人机分离作业,避免了农药中毒,降低了劳动强度,极大地提高了作业效率,达到减少农药使用量、提高农药利用率的目的。以水稻为对象,综述植保无人机在农药减量、水稻病虫害防效、技术简易性、农药利用率提升、水稻增产以及成本效益提升等发面发挥的作用。航空植保产业的迅速发展加快了植保无人机智能精准控制系统质量的提升和新技术的研发步伐,且植保无人机的普及性提出了飞防药剂、助剂和施药飘移风险控制技术研发的迫切需求,基于此进一步梳理总结了植保无人机低容量喷雾技术在农药减施增效中的作用和未来发展方向。     

Ethyl formate,formic acid and ethanol in air,wheat, barley and sultanas: analysis of natural levels and fumigant residues

Ethyl formate and ethanol in air, eg in fumigant studies, were readily detected by gas chromatography (GC) (flame ionisation). Residues in wheat, barley and sultanas were analysed by GC, after extraction in polar solvents (eg methanol, aqueous propanol). Both natural levels and levels resulting from fumigation with ethyl formate were measured. Formic acid was extracted from commodities with polar solvents (eg methanol, water) and analysed by GC after esterification. Solvent extracts of commodities were concentrated after addition of disodium hydrogen orthophosphate, and an aliquot added to acidified alcohols (several combinations of acids and alcohols were tested) in a sealed container. Formic acid esters were determined by GC, from headspace sampling over the esterification solvent. Esterification was faster with strong acids than with boric acid. However, esterification with boric acid/butanol gave the least interference of all tested methods. Product identity was confirmed by GC/mass spectrometry. High natural levels of formic acid, and low natural levels of ethyl formate and ethanol, presented problems in identifying residues arising from fumigation. These natural levels are relevant to food regulations for ethyl formate, especially those based on ‘total formic acid, free and combined’. Polar columns (eg FFAP, carbowax) were useful for measurement of formic acid esters, which eluted before the alcohols used for esterification or extraction, whereas elution followed the molecular mass on non-polar columns, such as GS-Q or DB-624. © 1999 Society of Chemical Industry     

Estimated exposure to glyphosate in humans via environmental,occupational, and dietary pathways: an updated review of the scientific literature

Glyphosate is one of the most widely used herbicides in the world, but it has also been the focus of discussion and restrictions in several countries since it was declared ‘probably carcinogenic to humans (Group 2A)’ by the International Agency for Research on Cancer in 2015. Since that time, several regulatory agencies have reviewed the public literature and guideline studies submitted for regulatory purposes and have concluded that it is not a carcinogen, and revised acceptable daily intakes (ADIs) and the reference dose (RfD) have been published. Also, restrictions on use have been lifted in many locations. Risk assessment for any pesticide requires knowledge of exposure in humans and the environment, and this paper is an update on a previous review in 2016 and includes papers published after 2016. These exposure data for air, water, bystanders, the general public, domesticated animals, pets, and applicators were combined and compared to the revised exposure criteria published by regulatory agencies. In all cases, measured and estimated systemic exposures to glyphosate in humans and animals were less than the ADIs and the RfD. Based on this large dataset, these exposures represent a de minimis risk. © 2019 Society of Chemical Industry     

高效液相色谱法测定噻唑锌在水、土壤及黄瓜中的残留

建立了采用高效液相色谱-二极管阵列检测器（HPLC-DAD）测定水、土壤和黄瓜中噻唑锌残留的方法。在碱性条件下先将噻唑锌转化为噻二唑（AMT）,采用外标法通过测定噻二唑的量来进行噻唑锌的定量分析。样品在40℃恒温振荡条件下,依次经Na2S转化及乙腈提取;过滤后调节混合液pH值至3,经乙酸乙酯液-液分配后,用HPLC-DAD及BDS Hypersil-C18色谱柱,以V（乙腈）:V（0.1%乙酸）=10:90为流动相,在313 nm波长下测定样品中的噻唑锌残留。结果表明:噻二唑在0.10~10 mg/L、噻唑锌在0.20~5.0 mg/L的质量浓度范围内线性关系良好（R2 > 0.999 5）,噻二唑的检出限（LOD）为0.05 mg/L。在0.2、1和5 mg/L添加水平下,噻唑锌在水中的平均回收率为100%~110%,相对标准偏差（RSD）为0.90%~6.4%;在0.05、0.5和5 mg/kg添加水平下,噻唑锌在土壤中的平均回收率为81%~98%,RSD为0.70%~2.8%;在0.05、0.5和2 mg/kg添加水平下,噻唑锌在黄瓜中的平均回收率为95%~102%,RSD为1.3%~4.2%。噻唑锌在水、黄瓜和土壤中的定量限（LOQ）分别为0.03 mg/L、0.05 mg/kg和0.05 mg/kg。本方法简单、准确、可靠,能满足农药残留分析的要求。     

Components of quantitative resistance to leaf rust in wheat cultivars: diversity,variability and specificity

The aim of this study was to investigate the potential diversity and pathogen‐specificity of sources of quantitative resistance to leaf rust caused by Puccinia triticina in French wheat germplasm. From a set of 86 genotypes displaying a range of quantitative resistance levels during field epidemics, eight wheat genotypes were selected and challenged in a greenhouse with three isolates of the pathogen, belonging to different pathotypes. Five components of resistance were assessed: infection efficiency, for which an original methodology was developed, latent period, lesion size, spore production per lesion, and spore production per unit of sporulating tissue. High diversity and variability for all these components were expressed in the host × pathotype combinations investigated; isolate‐specificity was found for all the components. The host genotypes displayed various resistance profiles, based on both the components affected and the isolate‐specificity of the interaction. Their usefulness as sources of quantitative resistance was assessed: line LD7 probably combines diversified mechanisms of resistance, being highly resistant for all the components, but displaying isolate‐specificity for all the components; cv. Apache did not show isolate specificity for any of the components, which could be related to the durability of its quantitative resistance in the field over more than 11 years.     

Weed composition and cover after three years of soil fertility management in the central Brazilian Amazon: Compost, fertilizer, manure and charcoal applications

Soils of the lowland tropics in the central Brazilian Amazon are generally highly leached, acidic and nutrient-poor. Charcoal, combined with other soil amendments, might improve fertility but this, in turn, could lead to increased weed problems for agricultural production. This experiment was conducted to assess weed pressure and species composition on plots receiving various inorganic and organic soil amendments, including charcoal. Additions of inorganic fertilizer, compost and chicken manure resulted in increases in weed ground cover of 40, 22 and 53%, respectively, and increases in species richness of 20, 48, and 63%, respectively. When chicken manure was applied, dominance by a few weed species was reduced, such that different species were more evenly represented. Although charcoal additions alone did not significantly affect weed ground cover or species richness, a synergistic effect occurred when both charcoal and inorganic fertilizers were applied. The percentage ground cover of weeds was 45% within plots receiving inorganic fertilizer, 2% within plots receiving charcoal and 66% within plots receiving both amendments. Improvements in the fertility of nutrient-poor soils of the tropics might increase weed pressure and make the development of effective weed management strategies more critical. These effects on weed populations were observed nearly 2.5 years after the addition of charcoal, chicken manure and compost, and > 1 year after the last application of inorganic fertilizer.     

Foliar resistance of cacao (Theobroma cacao) to Phytophthora palmivora as an indicator of pod resistance in the field: interaction of cacao genotype, leaf age and duration of incubation

The effects were studied of four leaf development stages (LDS) and three durations of incubation (DI) on the accuracy of leaf-disc tests on eight cacao (cocoa) clones (C) for predicting field resistance to phytophthora pod rot caused by Phytophthora palmivora . The clones were known to possess different general combining abilities (GCA) for pod resistance in the field, evaluated monthly at harvest over a 9-year period. Disease severity (DS) was affected strongly by C, DI and LDS, with increasing levels of significance. Two- and three-way interaction effects were smaller than the clone effect, but still significant. Clone effects were most significant for LDS3 (i.e. leaves 50–60 days old) and for DI5 and DI7 (observations made 5 and 7 days after inoculation, respectively). Coefficients of rank correlation between DS and field results were significant for seven of the 12 treatments, with highest values obtained again for treatments LDS3/DI5 ( r = 0·87) and LSD3/DI7 ( r = 0·93). Pooling of data for different LDS and DI treatments did not further improve the correlation with field results. However, these correlations were improved (from an average of 0·74 to 0·88) when the GCA values for field resistance were based on weekly observations, carried out in one year, including losses of pods and cherelles. It was concluded that, when carried out in a standardized manner and under optimal conditions, the leaf-disc test may explain 75–90% of the genetic variation for field resistance of cacao genotypes to P. palmivora .