Hematological and biochemical alterations in sprayers occupationally exposed to mixture of pesticides at a mango plantation in Lucknow,India

The aim of this study was to examine the hematological and cholinesterase (ChE) activity levels of pesticide sprayers employed in mango plantations at Lucknow. Fifty-two sprayers from mango plantations who regularly spray mixtures of pesticides including organochlorines (OC), organophosphates (OP), and carbamates were included as exposed group. Twenty residents living close to mango plantations, but not involved in pesticide spraying were taken as controls. Pesticide residues for OC were analyzed in blood by gas chromatography with electron capture detector. There was a significant decrease in acetylcholinesterase and butyrylcholinesterase activities in pesticide sprayers (n?=?52) relative to the control group (n?=?20). A significant difference in the frequency distribution of hematological variations in red blood cell, white blood cell, monocytes, neutrophils, mean corpuscular volume, mean corpuscular hemoglobin, mean corpuscular hemoglobin concentration, and platelet count was observed. Residues of OC pesticides including α-hexachlorocyclohexane (HCH) and total HCH were found to be significantly higher in the blood of sprayers compared to controls. Hematological variations were quantitatively more frequent among the sprayers with 5 years of pesticide exposure compared to the controls and to subjects with less than 5 years of exposure group. Hematological abnormalities in sprayers were correlated with pesticide exposure as evidenced by lower ChE activity as well as the presence of OC pesticides in blood. The poorly controlled use of pesticides in the plantation appeared to have produced sub-clinical intoxication in the sprayers and indicated the need for training and implementation of proper, safer hygiene practices.     

Determination of oxidative stress markers and serum cholinesterase among pesticide sprayers in southern Brazil

Small farmers generally spray pesticides manually and often do not use complete protective equipment. The standard test to detect pesticide exposure, which may be associated with toxicity, is the determination of serum cholinesterase, but in chronic exposure to low doses, this test is less sensitive. In this study, in a group sampled among pesticide sprayers without signs of intoxication, cholinesterase, thiobarbituric acid reactive substances (TBARS), catalase (Cat), and superoxide dismutase (Sod) activities were analyzed. Cholinesterase activity was only slightly lower in the farmer group in relation to the control group. However, TBARS and Cat activities were 3-fold increased in the farmers in comparison to the controls. Sod activity was similar in both groups. The group of pesticide sprayers that did not use the complete protective equipment presented a significantly higher level of TBARS than the group that used the complete protective equipment. Therefore, the determination of TBARS and catalase can be useful to identify individuals that are chronically exposed to low doses of pesticides.     

Endosulfan induced changes in phospholipids in the freshwater female catfish, Heteropneustes fossilis (Bloch)

The catfish, H. fossilis were exposed to endosulfan for 30 days at sub-lethal concentration (0.002 ppm) during different phases of its annual reproductive cycle. Its impact on total (TP) and different phospholipids- phosphatidylcholine (PC), phosphatidylserine (PS), phosphatdylinositol (Pl) and phosphatidylethanolamine (PE) were measured in liver plasma and ovary. On pesticide exposure, during preparatory phase, the hepatic TP PC and PE were declined. The plasma levels of TP, PC and PS were declined with the elevation of PE whereas in ovary only PC was lowered after endosulfan exposure. During pre-spawning phase, the hepatic TP, PC and PE declined in liver plasma and ovary after endosulfan exposure. During spawning phase, only plasma and ovarian phospholipids showed decrease in their levels following endosulfan exposure. In the post-spawning phase, endosulfan elevated the levels of TP, PC and PS in ovary but had no effect on their levels in liver and plasma. During resting phase, the TP, PC and Pl were found to be decreasing its levels. Thus it appears that this pesticide interfere with phospholipids metabolism during annual reproductive cycle of this species.     

国内外农药生态风险评价暴露模拟外壳述评

在阐明农药生态风险评价暴露模拟外壳的概念和功能的基础上,介绍了美国PE〔PRZM（pesticide root zonemodel）-EXAMS（exposure analysis modeling system）〕系列外壳和EXPRESS（EXAMS-PRZM exposure simulation shell）系列外壳、欧盟SWASH（surface water scenarios help）外壳及中国PRAESS（pesticide risk assessment exposure simula-tion shell）外壳这几种已开发的农药生态风险评价暴露模拟外壳的开发目的、结构组成、输入参数、运行方式和输出结果等方面的内容,并比较分析了各暴露模拟外壳在包含模型、包含场景、模拟水体类型和主要输出结果方面的异同点,期望为我国农药生态风险评价,尤其是暴露评价研究提供有益借鉴。     

农药暴露的机制模型：蜜蜂毒理学的重要缺失

杀虫剂在最近的蜜蜂数量减少中所扮演的角色是有争议的,部分原因是实地研究常常无法检测到实验室研究所预测的效果。这种不一致性突出了蜜蜂毒理学研究领域的一个关键空白：对蜜蜂在它们的环境中杀虫剂暴露的模式和过程知之甚少。本文作者提出蜜蜂暴露杀虫剂的2个关键过程：1)工蜂采集花蜜的过程中收集农药;2)工蜂带回的农药在蜂巢中的再分配。工蜂收集农药的过程必须被理解为环境污染和蜜蜂觅食活动之间的时空交集。这意味着农药暴露是分配的,而不是离散的,觅食工蜂的一个子集可能会获得有害剂量的农药,而群体暴露将会显得安全。蜂箱中农药的分布是一个复杂的过程,主要是由群体成员之间食物转移的相互作用而产生,而这一过程中花粉和花蜜之间有重要的区别。因此应该优先将关于蜜蜂生物学的大量文献用于发展更严谨的蜂蜜农药暴露机制模型。与效应机制模型结合,暴露机制模型具有整合蜜蜂毒理学领域的潜力,以促进风险评估和基础研究。
精选自Sponsler, D. B. and Johnson, R. M. (2017), Mechanistic modeling of pesticide exposure: The missing keystone of honey bee toxicology. Environmental Toxicology and Chemistry, 36: 871–881. doi: 10.1002/etc.3661
详情请见http://onlinelibrary.wiley.com/doi/10.1002/etc.3661/full
     

Multiseasonal management of an agricultural pest. I: Development of the theory

A framework for analyzing the trade-off between economic yield from a crop and buildup of resistance to pesticide caused by repeated applications of pesticide is developed. The analysis begins with the case of age-independent pest dynamics, in which pests infest a field by arriving from an external pool. Initially, it is assumed that the pest genetics of interest are single locus, two allele, with resistance to pesticide dominant and susceptible pests more fit in the absence of spraying. The pesticide is applied only once during the season, with timing and intensity of the application as control variables. Interseasonal pest and crop dynamics are studied by solving appropriate ordinary differential equations. Intraseasonal pest dynamics are assumed to follow the Hardy-Weinberg formula. It is shown that the three class diploid model can be replaced by a two class haploid model with essentially no change in the results. A model based on partial differential equations is developed, for the case in which pest dynamics depend upon age, and it is shown that the partial differential equation model can be replaced by a pair of coupled ordinary differential equations. The main operational conclusion in this paper is that the timing of the application of pesticide can be used to control buildup of resistance and that the intensity of the application can be used to control the crop yield.     

Effect of pesticides carbaryl and phorate on serum cholesterol level in fish,Clarias batrachus (Linn)

Freshwater edible catfish Clarias batrachus (Linn.) was treated with sublethal concentration of two different groups of pesticides- carbaryl, a carbamate and phorate, an organophosphate for 24 ,72 ,120 and 168 h. The disorders of lipid metabolism were observed in serum. Cholesterol levels in the serum decreased significantly throughout the exposure period with both the pesticides. These results indicate one significant manifestation of the toxic response from the fish under the stress of pesticide exposure.     

Effect of curacron toxicity on the total serum protein content of Cyprinus carpio

An experiment was conducted on freshwater fish Cyprinus carpio to study the effect of the pesticide curacron on total serum protein. Curacron is an organophosphate pesticide and used by the farmers to protect their crops. This pesticide reaches the aquatic ecosystem by direct or indirect means and affects aquatic fauna. LC50 for curacron for C. carpio was calculated by the log-dose/probit regression line method and found to be 0.38?ppm at 96?h. Three sub-lethal concentrations (0.1, 0.01, and 0.001?mL?L^?1) were selected to expose the fish for 1, 7, 14, and 21days. Changes in total serum protein were observed at all pesticide concentrations and exposure periods. Total serum protein was decreased from control. At 1 and 7 days, the decrease was quantitative at all concentrations, while at 14 and 21 days, the fall was significant at all concentrations. Hence, human population may be at risk by consuming these contaminated fish.     

欧美农药环境降解动力学评估方法比较

农药在环境中的降解行为是评估农药环境安全性的基础,农药的降解动力学通常以一级动力学模型描述。现有的环境暴露模型也均需要输入一级动力学模型的农药在土壤中50%消失时间(DT50)。但有时一级动力学模型不适用于描述农药在环境中,特别是土壤中的降解。因此欧盟和北美自由贸易区已发布了一系列关于使用非一级动力学模型计算DT50的导则。介绍了欧美降解动力学评估方法,并用多组降解数据比较了2种评估方法的区别。     

Review: Windows of exposure to pesticides for increased risk of childhood leukemia

Leukemia is the leading cause of cancer resulting in mortality of children, and there is some evidence suggesting the increased incidence rate increasing during the recent decades. Limited human evidence indicates an increased risk of developing leukemia in childhood as a result of pesticide exposure, with possible significance of exposure occurring during the developmental periods including preconception, pregnancy, and childhood. This review examines the results of relevant literature on the timing of pesticide exposure and leukemia diagnosed in childhood. Results suggest that the risk from pesticide exposure seems to be greater during pregnancy. Other findings indicate that maternal occupational exposure may be more of a greater concern than the paternal occupational exposure; and that the residential indoor use of pesticides tends to result in higher risk estimates than the residential outdoor use. Only limited data are available on particular pesticides, genetic factors, critical windows of exposure during development, and their association with different histological types of leukemia.     

Economic losses associated with the degradation of an ecosystem: The case of submerged aquatic vegetation in Chesapeake Bay

This study employs theoretical and empirical concepts from ecology and economics to derive a lower bound of the marginal damage function for reductions in the level of submerged aquatic vegetation (SAV) in Chesapeake Bay. These reductions in SAV are believed to be a consequence of the runoff of agricultural chemicals, discharges from waste treatment plants, and soil erosion. The study examines the indirect ecological consequences of pollution in Chesapeak Bay fisheries, in a fashion which is consistent with the economic theory of benefit measurement.     

农药在稻田使用对地下水的风险评估研究进展

农药风险评估可为农药登记和农药的环境安全管理提供重要的科学依据。水稻生产过程中病虫草害严重,农药使用品种多、频次高,田水存留时间长,对地下水污染风险高。开展农药在稻田使用对地下水的风险评估研究具有重要的现实意义。文章详细介绍了欧盟和美国的水稻-地下水风险评估研究进展,包括风险评估程序、暴露评估模型及暴露场景等。总结了我国农药在稻田使用对地下水风险评估的研究现状,并分析了我国研究的不足之处。在此基础上,提出了加强我国农药在稻田使用对地下水风险评估的建议。     

Pesticide in the Mississippi River floodplain and its possible linkage to colon cancer risk in the US

Result of this study shows that elevated colorectal cancer risk in Mississippi River floodplain of the United States is likely linked to historically high pesticide application. Mississippi River basin produces about 80% of major US crops and has about two-thirds of US pesticides used for agriculture. Historically, heavy pesticide application and agricultural irrigation were reported to result in high pesticide residues in surface water, fish and wells of Mississippi embayment. Risk ratio of colorectal cancer incidence in 86 counties of Mississippi River floodplain was about 29% higher than that of other counties in the 48 contiguous states. Risk ratio of colon cancer mortality in 63 counties of Mississippi embayment was 33% higher than that of other counties in the 48 states between 1999 and 2016. Risk ratios of colorectal cancer incidence and colon cancer mortality in Mississippi River floodplain are higher after smoking and diabetes factors were filtered off. Previous studies have linked exposure to pesticide with type-II diabetes and the latter was linked to increasing colon cancer risk by about 27%. Result here suggests that pesticide may be an independent risk factor directly associated with elevated colon cancer risk in Mississippi River floodplain.     

Nerve conduction studies in sprayers occupationally exposed to mixture of pesticides in a mango plantation at Lucknow,North India

In this study, nerve conduction, organochlorine (OC) pesticide residues in blood and cholinesterase activity levels of pesticide sprayers employed in mango plantations at Lucknow, North India, were determined. Fifty-two sprayers from mango plantations who regularly spray mixture of pesticides like organophosphates (OP), OCs, and carbamates were considered as exposed group. Eighteen subjects with similar socio-economic status of exposed group, who do not handle pesticides, were selected as controls. Questionnaire-based interviews related to personal and occupational histories of the study subjects were carried out. Sprayers did not use any personal protective equipment during pesticide handling. The blood-pesticide analyses of sprayers show higher mean values of hexachlorohexane (HCH), γ-HCH, δ-HCH, total HCH, op-DDT compared with the controls. Acetylcholinesterase (AChE) and butyrylcholinesterase (BChE) activites were significantly reduced among sprayers. Risk of motor nerve conduction deficits was observed in sprayers with low AChE activity. Negative correlation of motor and sensory nerve conduction deficits was observed with the duration of exposure and age among sprayers. The study demonstrated that the prolonged exposure to mixture of pesticides, ergonomic factors, decline in cholinesterase activity may lead to nerve conduction dysfunction. The findings suggest the need for controlled use of pesticides in the plantation and indicated the need for training and implementation of hygiene practices like proper usage of personal protective equipments.     

Characterisation and expression of four mRNA sequences encoding glutathione S-transferases pi,mu, omega and sigma classes in the Pacific oyster<Emphasis Type="Italic"> Crassostrea gigas</Emphasis> exposed to hydrocarbons and pesticides

Hydrocarbon and pesticide pollution in coastal ecosystems can disturb marine bivalve metabolism. In this study, we characterised four full-length cDNA sequences encoding glutathione S-transferases (GSTs) in the Pacific oyster Crassostrea gigas. A BLAST X search showed that these four sequences encode GSTs from four different classes: GST pi, sigma, mu and omega. A phylogenetic analysis of GST was made to determine the position of oyster GST compared to invertebrate and vertebrate sequences. We developed a semi-quantitative, multiplex RT-PCR to follow the expression of these four GSTs in tissues of oysters exposed to hydrocarbons and two pesticide treatments (glyphosate and a mixture composed of atrazine, diuron and isoproturon) under experimental conditions. Our results showed strong differential expression of these four GSTs that was both tissue specific as well as time and treatment dependent. We observed that expression levels were higher in digestive gland than in gill tissues in pesticide-exposed oysters. Furthermore, omega and mu class GST mRNA expression in the digestive gland might be useful as a possible marker of hydrocarbon exposure, while pi and sigma class GST mRNA expression in the digestive gland may be similarly useful as a marker of pesticide exposure in monitoring programmes.Communicated by S.A. Poulet, Roscoff     

Direct determination of dichlorvos in water by partial least square-discriminant analysis

This report describes a rapid, onsite method to analyze the dichlorvos pesticide in water. Dichlorvos is a broad-spectrum pesticide that has been used worldwide. As an organophosphorus pesticide, dichlorvos disrupts the nervous system by inhibiting the activity of acetyl cholinesterase. Traditional analysis of dichlorvos by chromatography is time-consuming and environmentally unfriendly. Therefore, rapid, on-site methods to analyze dichlorvos are needed. Here, we used for the first time Fourier transform near infrared spectroscopy combined with partial least square-discriminant analysis to determine the dichlorvos directly in water samples. Results were compared with traditional high-performance liquid chromatography data as reference. We found that over 9,000–8,333?cm^?1, the new method had a good performance with a classification accuracy of 100?% and a correlation coefficient of 0.92 between measured and reference data. The new method can also be used as a “concentration sieve” by setting up different levels of boundary, a parameter of partial least square-discriminant analysis, thus allowing rapid on-site screening.     

Biomonitoring insecticide pollution using non-target soil microarthropods

The scope of biomonitoring insecticide pollution in soil is discussed with the help of field and laboratory findings on the density, prey-predator ratio and fecundity of non-target microarthropod fauna. Field experiments were conducted in small plots with mustard, wheat and lady's finger crops and insecticides namely heptachlor 20EC (3.25 kg ai/ha = 16.25 lit/ha) and endosulfan 35EC (0.875 kg ai/ha = 2.5 lit/ha) applied at the seedling stages. Soil microarthropod population estimated at fortnightly intervals in the treated and untreated control plots revealed a general trend of adverse effect of the insecticides, prominently on the density and relative abundance of major prey groups like Collembola and Acari leading to notable decline in prey-predator ratio. Comparison of the percentage reductions of major taxonomic and trophic groups between pre-treatment and post-treatment intervals also demonstrated the ill effect of both heptachlor and endosulfan, notably on Collembola and the prey category. In the laboratory the survival success and fecundity of Cyphoderus javanus (Collembola) and Archegozetes longisetosus (Acari) were compared by exposing freshly emerged adults to sub-lethal concentrations of heptachlor and endosulfan for varying durations. The untreated control sets recorded high fecundity for both C. javanus and A. longisetosus, but chronic toxicity of the insecticides on adults confined to the treated soil resulted into very low fecundity. Even short duration exposure to heptachlor and endosulfan treated soil for 24 or 72 hours only was found to delay the egg-laying and decrease the fecundity of both the species. It is concluded that population responses and reproductive sensitivity in non-target soil microarthropods are potential eco-toxicological parameters for detecting pesticide pollution in soil and for ecological health assessment since the results are based on the bioactivity of toxicants.     

Effects of sublethal concentrations of isoxaben on the development of the African clawed frog,Xenopus laevis

Agricultural pesticide exposure is one factor implicated in the decline of amphibian abundance in aquatic ecosystems. Isoxaben is a cellulose biosynthesis inhibitor mainly used for roadside weed control, suggesting that isoxaben can run off during rain events and potentially affect amphibian development. This study followed the development of African clawed frog (Xenopus laevis) tadpoles exposed to different environmentally relevant concentrations of isoxaben. No significant adverse effects were observed on days to metamorphosis or size and weight at metamorphosis. This reinforces the conclusion that isoxaben herbicide application at low environmental concentrations is not a substantial risk to wildlife.     

Pesticide use and health outcomes: Evidence from agricultural water pollution in China

By linking provincial pesticide usage reports from several Chinese statistical yearbooks (1998-2011) with the Chinese Longitudinal Healthy Longevity Survey (1998-2011), this study provides new evidence that pesticides adversely affect health outcomes via drinking water exposure. We follow a difference-in-difference-in-differences framework to compare health outcomes between people who drink surface water and ground water in regions with different intensities of rice pesticide use before and after 2004, when China shifted from taxing agriculture to subsidizing agricultural programs. The results indicate that a 10% increase in rice pesticide use unfavorably alters a key medical disability index (Activities of Daily Living or ADL) by 1% for rural residents 65 and older. This is equivalent to 2.13 and 0.64 million dollars in medical and family care costs, respectively. Further, we provide suggestive evidence of an intergenerational transfer of caring burden by showing pesticide use reduces out-migration of the offspring in affected households. The results are robust to a variety of robustness checks and falsification tests.     

Visual disturbances with cholinesterase depletion due to exposure of agricultural pesticides among farm workers

In this study, risk assessment for visual disturbances among farm workers spraying agricultural pesticides in farms have been assessed. A cross-sectional study for the assessment of visual disturbances was undertaken using questionnaire survey and clinical examination among agricultural workers exposed to pesticides. Two hundred and thirty nine pesticide sprayers participated in the study. The study was compared to 110 controls not occupationally exposed to pesticides with similar socio-economic status. The prevalence of ocular morbidity was found to be 40% among pesticide sprayers which was significantly higher (p?p?相似文献