Food poisoning due to methamidophos-contaminated vegetables

BACKGROUND: Organophosphate poisoning is well known for its characteristic symptoms and signs, but food poisoning caused by pesticide-contaminated food is seldom reported. CASE REPORT: We report three incidents of food poisoning that resulted from exposure to the organophosphate insecticide methamidophos in vegetables. These outbreaks caused a cholinergic syndrome in 4 patients. The cholinergic overactivity led as to suspect organophosphate food poisoning. All patients recovered well following appropriate therapy. The clinical diagnosis of organophosphate poisoning was confirmed by reduced levels of erythrocytes and plasma cholinesterase and the presence of methamidophos in the vegetable leftovers. The implicated vegetables and levels of methamidophos were: Ipomoea batatas 255 ppm, Gynura bicolor 110 ppm, and red cabbage 26.3 ppm. Since methamidophos is normally applied to vegetables during planting, improper selection and/or overuse of pesticide or improper harvest times may explain the occurrence of these high residue levels of methamidophos.     

Neurologic symptoms in licensed pesticide applicators in the Agricultural Health Study

Exposure to high levels of many pesticides has both acute and long-term neurologic consequences, but little is known about the neurotoxicity of chronic exposure to moderate pesticide levels. We analysed cross-sectional data from 18 782 Caucasian, male, licensed pesticide applicators, enrolled in the Agricultural Health Study from 1993 to 1997. Applicators provided information on lifetime pesticide use, and 23 neurologic symptoms typically associated with pesticide intoxication. Increased risk of experiencing >/=10 symptoms during the year before enrollment was associated with cumulative pesticide use, personally mixing or applying pesticides, pesticide-related medical care, diagnosed pesticide poisoning, and events involving high personal pesticide exposure. Greatest risk was associated with use of organophosphate and organochlorine insecticides. Results were similar after stratification by pesticide use during the year before enrollment, or exclusion of applicators with a history of pesticide poisoning, or high-exposure events. Use of pesticide application methods likely to involve high personal exposure was associated with greater risk. Groups of symptoms reflecting several neurologic domains, including affect, cognition, autonomic and motor function, and vision, were also associated with pesticide exposure. These results suggest that neurologic symptoms are associated with cumulative exposure to moderate levels of organophosphate and organochlorine insecticides, regardless of recent exposure or history of poisoning.     

Pesticide exposure and genetic variation in xenobiotic-metabolizing enzymes interact to induce biochemical liver damage

Metabolic activation of pesticides in the liver may result in highly reactive intermediates capable of impairing various cellular functions. Nevertheless, the knowledge about the effect of pesticide exposure on liver function is still limited. This study assessed whether exposure to pesticides elicits early biochemical changes in biomarkers of liver function and looked for potential gene-environmental interactions between pesticide exposure and polymorphisms of pesticide-metabolizing genes. A longitudinal study was conducted in farm-workers from Andalusia (South Spain), during two periods of the same crop season with different degree of pesticide exposure. Blood samples were taken for the measurement of serum and erythrocyte cholinesterase activities as well as for determining clinical chemistry parameters as biomarkers of liver function. Serum lipid levels were also measured as they may help to monitor the progress of toxic liver damage. A reduction in serum cholinesterase was associated with decreased levels of all clinical chemistry parameters studied except HDL-cholesterol. Conversely, a decreased erythrocyte cholinesterase (indicating long-term pesticide exposure) was associated with increased levels of aspartate aminotransferase and alkaline phosphatase and increased levels of triglycerides, total cholesterol and LDL-cholesterol, but reduced levels of HDL-cholesterol. Changes in liver biomarkers were particularly associated with the PON1_55M/192R haplotype. The obtained results therefore support the hypothesis that pesticide exposure results in subtle biochemical liver toxicity and highlight the role of genetic polymorphisms in pesticide-metabolizing enzymes as biomarkers of susceptibility for developing adverse health effects.     

The impact of repeated organophosphorus pesticide exposure on biomarkers and neurobehavioral outcomes among adolescent pesticide applicators

Egyptian adolescents are hired as seasonal workers to apply pesticides to the cotton crop and may perform this occupation for several years. However, few studies examined the effects of repeated pesticide exposure on health outcomes The goal of this study was to determine the impact of repeated pesticide exposure on neurobehavioral (NB) performance and biomarkers of exposure (urinary metabolite) and effect (cholinesterase activity). Eighty-four adolescents from two field stations in Menoufia, Egypt, were examined four times: before and during pesticide application season in 2010 and again before and during application season in 2011. At each of the four time points, participants completed a questionnaire, performed an NB test battery, and were assessed for urinary levels of the chlorpyrifos metabolite TCPy (3,5,6-trichloro-2-pyridinol) and blood cholinesterase activity. Following the study cohort over two consecutive pesticide application seasons revealed that TCPy levels significantly increased following exposure, and returned to baseline levels following the end of the application season. Blood butyryl cholinesterase activity exhibited a similar pattern. Although NB outcomes displayed learning and practice effects over time, deficits in performance were significantly associated with increased TCPy levels with reduction in the number of NB measures showing improvement over time. Biomarkers of exposure and effect demonstrated changes associated with pesticide application and recovery after application ended. Deficits in NB performance were correlated with elevated pesticide exposure. Data demonstrated that repeated pesticide exposure may exert a long-term adverse impact on human health.     

Pesticides and children

Prevention and control of damage to health, crops, and property by insects, fungi, and noxious weeds are the major goals of pesticide applications. As with use of any biologically active agent, pesticides have unwanted side-effects. In this review, we will examine the thesis that adverse pesticide effects are more likely to occur in children who are at special developmental and behavioral risk. Children's exposures to pesticides in the rural and urban settings and differences in their exposure patterns are discussed. The relative frequency of pesticide poisoning in children is examined. In this connection, most reported acute pesticide poisonings occur in children younger than age 5. The possible epidemiological relationships between parental pesticide use or exposure and the risk of adverse reproductive outcomes and childhood cancer are discussed. The level of consensus among these studies is examined. Current concerns regarding neurobehavioral toxicity and endocrine disruption in juxtaposition to the relative paucity of toxicant mechanism-based studies of children are explored.     

Effect of long-term exposure to pesticides on plasma esterases from plastic greenhouse workers

Previous reports in animals considered beta-glucuronidase activity as a novel biomarker of anticholinesterase (organophosphates and carbamates) pesticides exposure. Acid phosphatase activity was also shown to increase after organophosphates exposure. In addition, there is evidence that the paraoxonase status influences sensitivity to specific pesticides. In this study, activities of beta-glucuronidase, acid phosphatase, cholinesterase, and paraoxonase were measured in plasma from plastic greenhouse workers exposed over the long term to different pesticides, including organophosphates and carbamates, in order to evaluate the potential chronic toxicity of pesticides at occupational level. Our results show that activities of paraoxonase and cholinesterase were decreased in applicators of pesticides compared to non-applicators. Likewise, it was found that activities of beta-glucuronidase and acid phosphatase were associated with pesticide exposure in humans, and that both biochemical parameters were related to each other. Interestingly, the paraoxonase B allele (phenotyped in plasma) was associated with a higher risk of inhibition of cholinesterase activity above a 25% level, which supports the hypothesis that paraoxonase phenotypes are associated with susceptibility of humans to anticholinesterase pesticides toxicity.     

某市2006至2011年非生产性农药中毒情况的分析

目的探讨某市非生产性农药中毒状况,以制定有效管理措施,控制因非生产性农药给人体带来的危害,降低农药中毒的发生率和病死率。方法收集2006~2011年诸城市农药中毒报告卡,用SPSS进行统计分析。结果农药中毒病例360例,非生产性农药中毒354例,非生产性农药中毒年平均发病率为5.52/10万,死亡12例,病死率为3.39%。非生产性误服农药中毒男女比例为1.31∶1;非生产性自服农药中毒男女比例为1∶1.25。非生产性误服农药中毒以<15岁年龄组和55~64岁年龄组为主;非生产性自服农药中毒以25~44岁年龄组人数最多。农村非生产性误服和自服农药中毒发病率均明显高于城区,引起非生产性中毒的主要农药以杀虫剂中的有机磷类农药、拟菊酯类和除草剂为主,中毒高峰期发生在第三季度。结论某市非生产性农药中毒情况比较严重,应积极采取并落实有效的控制措施,推广使用高效低毒、低残留农药,加强农药监督管理工作,加强宣传教育,提高对农药危害的认识,提高农民思想素质,有效防止非生产性农药中毒。     

Is plasma beta-glucuronidase a novel human biomarker for monitoring anticholinesterase pesticides exposure? A Malaysian experience

A cross-sectional study was conducted to investigate the effects of acute and chronic pesticide exposure on the plasma beta-glucuronidase enzyme activity among five patients of acute pesticide poisoning in Tengku Ampuan Rahimah Hospital, Klang, 230 farmers in the MADA area, Kedah and 49 fishermen in Setiu, Terengganu. The duration of pesticide exposure among the patients was unknown, but the plasma samples from patients were collected on day one in the hospital. The duration of pesticide exposure among the farmers was between 1 and 45 years. The beta-glucuronidase activity was compared with plasma cholinesterase activity in the same individual. The plasma cholinesterase activity was measured using Cholinesterase (PTC) Reagent set kit (Teco Diagnostics, UK) based on colorimetric method, while the plasma beta-glucuronidase activity was measured fluorometrically based on beta-glucuronidase assay. The plasma cholinesterase activity was significantly reduced (p<0.05) among the patients (1386.786+/-791.291 U/L/min) but the inhibition in plasma cholinesterase activity among the farmers (7346.5+/-1860.786 U/L/min) was not significant (p>0.05). The plasma beta-glucuronidase activity among the farmers was significantly elevated (p<0.05) (0.737+/-0.425 microM/h) but not significant among the patients (p>0.05). The plasma cholinesterase activity was positively correlated with the plasma beta-glucuronidase activity among the farmers (r=0.205, p<0.01) but not among the patients (r=0.79, p>0.05). Thus, plasma beta-glucuronidase enzyme activity can be measured as a biomarker for the chronic exposure of pesticide. However, further studies need to be performed to confirm whether plasma beta-glucuronidase can be a sensitive biomarker for anticholinesterase pesticide poisoning.     

Pesticide exposure--Indian scene

Use of pesticides in India began in 1948 when DDT was imported for malaria control and BHC for locust control. India started pesticide production with manufacturing plant for DDT and benzene hexachloride (BHC) (HCH) in the year 1952. In 1958, India was producing over 5000 metric tonnes of pesticides. Currently, there are approximately 145 pesticides registered for use, and production has increased to approximately 85,000 metric tonnes. Rampant use of these chemicals has given rise to several short-term and long-term adverse effects of these chemicals. The first report of poisoning due to pesticides in India came from Kerala in 1958 where, over 100 people died after consuming wheat flour contaminated with parathion. Subsequently several cases of pesticide-poisoning including the Bhopal disaster have been reported. Despite the fact that the consumption of pesticides in India is still very low, about 0.5 kg/ha of pesticides against 6.60 and 12.0 kg/ha in Korea and Japan, respectively, there has been a widespread contamination of food commodities with pesticide residues, basically due to non-judicious use of pesticides. In India, 51% of food commodities are contaminated with pesticide residues and out of these, 20% have pesticides residues above the maximum residue level values on a worldwide basis. It has been observed that their long-term, low-dose exposure are increasingly linked to human health effects such as immune-suppression, hormone disruption, diminished intelligence, reproductive abnormalities, and cancer. In this light, problems of pesticide safety, regulation of pesticide use, use of biotechnology, and biopesticides, and use of pesticides obtained from natural plant sources such as neem extracts are some of the future strategies for minimizing human exposure to pesticides.     

血液灌流在重度有机磷农药中毒治疗中的应用研究

目的探讨血液灌流（HP）在重度有机磷农药中毒中的作用。方法收集该院重度有机磷农药中毒患者87例,观察患者昏迷清醒时间、胆碱酯酶恢复时间及机械通气时间。结果各组昏迷清醒时间、胆碱酯酶恢复时间及机械通气时间比较差异均有统计学意义（P〈0.05）。结论在常规治疗基础上行HP治疗重度有机磷农药中毒,患者昏迷清醒时间、胆碱酯酶恢复时间及机械通气时间均明显缩短,且越早进行HP治疗受益越早。     

The health status of northern Omo State Farm workers exposed to chlorpyrifos and profenofos

The health effects of organophosphorus (OP) pesticides on cholinesterase (ChE) activities were assessed among 81 pest control workers from Northern Omo State Farm (Ethiopia), following the occupational use of Chlorpyrifos 25 and 48% ULV and Profenifos 250 EC/ULV. Plasma ChE (PChE) and erythrocyte ChE (AChE) activities were determined electrometrically before and after pesticide exposure. Plasma alkaline phosphatase (AP) and glutamic pyruvic transaminase (GPT) values were estimated colorimetrically. Risk factors of pesticide poisoning and related occupational factors were assessed following the WHO recommendations. The mean PChE and AChE activities determined after pesticide exposures were significantly lower than the pre-exposure values (P < 0.05); 16% and 40% of the pest control workers had PChE and AChE levels below 50% of the pre-exposure values, respectively. The mean plasma AP and GPT values were found to be within the recommended normal limits. No significant difference in either of the ChE activities was observed between the spray men and the pest assessors, although the former were believed to have frequent contact with the concentrated OP formulations. Risk factors of pesticide poisoning such as workers ignorance about the toxicity of pesticides, poor personal hygiene and total absence or improper use of personal protective devices were prevalent. Measures that should be considered to minimize the problem in the farm population are recommended.     

Effect of systemic exposure to parathion on the dark adapted pupil dilation of cynomolgus monkeys

The constriction of pupil dilation following dark adaptation was studied as a potentially useful biological monitor of systemic exposure to organophosphorus pesticides (OPs). Pupil dilation and blood cholinesterase levels were monitored in 4 cynomolgus monkeys following oral administration of 2.0 mg/kg parathion in corn oil. No consistent pattern of change in pupil/iris diameter ratios following exposure was found despite depressions in blood cholinesterase activities of 27-50% for red cells and 65-80% for plasma. A slight mydriasis was observed in one of the monkeys, who appeared the most affected behaviorally by the exposure. Results of this work suggest that the measurement of pupil dilation after dark adaptation is not a sensitive indicator for systemic exposure to OPs. However, in situations where direct exposure to the eyes may occur, such as during aerial or airblast pesticide applications, other studies indicate that constriction of pupil dilation can occur at exposure levels below those resulting in systemic effects.     

血浆置换治疗重度有机磷农药中毒临床统计

目的观察血浆置换治疗重度有机磷农药中毒病例的疗效。方法回顾性统计笔者所在医院2006年~2010年采用血浆置换治疗重度有机磷农药中毒病例9例。结果术后胆碱酯酶-术前胆碱酯酶秩和检验有极显著性差异(P<0.01),其中7例治愈,1例放弃治疗出院,1例死亡,抢救成功率87.5%。结论血浆置换治疗能迅速降低中毒病例血液中有机磷农药含量,提高血液中胆碱酯酶活力,具有良好的临床效果。     

有机磷农药中毒病例的临床分析

对124例有机磷农药中度的患者进行回顾性分析,探讨血胆碱酯酶活性降低与临床中毒程度之间的关系。结果显示,血胆碱酯酶活性降低与临床中毒程度间不一定一致,临床治疗应综合分析,合理治疗,以免贻误治疗的最佳时间。     

间歇性洗胃法救治48例有机磷农药中毒患者的效果观察

目的比较间歇性洗胃法和传统洗胃法治疗有机磷农药中毒疗效区别。方法将符合有机磷中毒诊断标准的96例患者随机分为治疗组和对照组.治疗组采用间歇性洗胃法.对照组采用传统洗胃法.观察两组患者使用阿托品量,出现反跳现象例数以及住院天数.检测全部患者治疗前,第一次洗胃后8h,24h,72h时全血胆碱酯酶活性值。结果治疗组患者在阿托品使用量,反跳现象例数,及住院天数明显优于对照组(P<0.05)。第一次洗胃后8h.24h,72h检测全血胆碱酯酶活性值,治疗组均高于对照组(P<0.05)。结论间歇性洗胃法能够减少阿托品用量,减少反跳现象发生率,缩短住院天数,治疗有机磷中毒疗效更好。     

早期血液灌流对急性有机磷农药中毒血清胆碱酯酶活力恢复临床观察

目的 观察早期血液灌流对急性有机磷农药中毒血清胆碱酯酶活力恢复作用.方法 回顾性分析该院在2004年1月-2005年1月以及2011年1月-2012年1月采用血液灌流（HP组,n=40）或非血液灌流（非HP组,n=40）治疗80例急性有机磷农药中毒患者的临床资料.结果 两组患者的中毒农药种类和治疗前的血清胆碱酯酶活力值都无显著性差异（P〉0.05）,但是HP的长托宁用量、氯磷定用量,机械通气时间,昏迷时间,住院时间、血清胆碱酯酶活力恢复情况以及并发症情况都优于非HP组.结论 早期血液灌流治疗急性有机磷农药中毒的临床疗效显著,可促进患者的胆碱酯酶活力极早恢复,有效提高救治成功率.     

农药中毒患者治疗前后胆碱酯酶的变化分析

目的探讨农药中毒患者采用血液透析治疗前后胆碱酯酶的变化。方法农药中毒患者16例根据治疗方法的不同分为治疗组与对照组各8例，对照组采用传统方法治疗，治疗组在此基础上采用了血液灌流治疗。结果治疗组的生存率为100．0％，对照组的生存率为75．0％，组间对比有明显差异（P〈O．05）。两组治疗前血清胆碱酯酶活力对比无明显差异，哥治疗后存活者的组间与组内对比有明显差异（P〈O．05）。治疗组存活者住院时间明显高高于对照组（P〈0．05）。结论农药中毒患者采用血液灌注治疗能取得很好的预后效果，其疗效的发挥可能与恢复胆碱酯酶活力有关。     

急性有机磷农药中毒118例急救体会

目的:探讨急性有机磷农药中毒的急救方法.方法:回顾性分析118例急性有机磷农药中毒的临床资料.结果:118例患者轻度、中度中毒者均治愈,重度中毒患者死亡4例,抢救成功率96.61%.结论:彻底清除毒物、洗胃,正确使用阿托品和胆碱酯酶复能剂是抢救有机磷农药中毒成功的关键.     

Changes in erythrocyte enzymes in humans long-term exposed to pesticides: influence of several markers of individual susceptibility

Changes in erythrocyte delta-aminolevulinic acid dehydratase (ALA-D) have been reported after exposure to different pesticides, including organophosphates and paraquat. In this study, we have determined ALA-D in 135 pesticide applicators (sprayers) from an intensive agriculture setting at two periods with different pesticide exposure. Acetylcholinesterase (AChE) was used as a reference biomarker. The effects of the combined polymorphism of enzymes involved in the detoxification of pesticides (paraoxonase (PON1), benzoylcholinesterase (BChE), and glutathione S-transferase (GSTM1 and GSTT1)) on the level of the target erythrocyte enzymes were also studied as biomarkers of individual susceptibility. Sprayers presented significant lower levels of ALA-D and AChE than controls (41.3% and 14.5%, respectively) at the high exposure period. When all biomarkers of individual susceptibility to pesticides were considered at the same time, the GSTT1 null allele determined higher ALA-D and AChE activities at the period of high exposure to pesticides. PON1 R allele in turn determined lower AChE activity at the low exposure period. Null genotype for both GST subclasses (GSTM1 and GSTT1) was found to be the unique independent predictor of pesticide-related symptomatology. Interestingly, sprayers were consistently underrepresented among carriers of "unfavourable" BChE variants. In conclusion, ALA-D appears to be an important biological indicator of pesticide exposure and PON1 and GSTT1 are relevant determinants of susceptibility to chronic pesticide poisoning.     

Oxidative stress in acute human poisoning with organophosphorus insecticides; a case control study

Free radicals play an important role in toxicity of pesticides and environmental chemicals. Organophosphorus insecticides (OPIs) may induce oxidative stress leading to generation of free radicals and alteration in antioxidant system. To complete the previous surveys, this study was conducted to evaluate the existence of oxidative stress, balance between total antioxidant capacity and oxygen free radicals in patients with acute OPI exposure. In this case control study, a total of 22 acute OPI poisoning patients were included and blood samples were analyzed for lipid peroxidation, total antioxidant capacity, total thiol groups, and cholinesterase levels. The results showed significant lipid peroxidation accompanied with decreased levels of total antioxidant capacity, total thiols, and cholinesterase activity. A significant correlation existed between cholinesterase depression and reduced total antioxidant capacity. It is concluded that oxygen free radicals and their related interactions like lipid peroxidation are present in acute OPI poisoning. Use of antioxidants may be beneficial in treatment of OPIs acute poisoning which remains to be elucidated by further clinical trials.