Effectiveness of household lockable pesticide storage to reduce pesticide self-poisoning in rural Asia: a community-based, cluster-randomised controlled trial

BACKGROUND

Agricultural pesticide self-poisoning is a major public health problem in rural Asia. The use of safer household pesticide storage has been promoted to prevent deaths, but there is no evidence of effectiveness. We aimed to test the effectiveness of lockable household containers for prevention of pesticide self-poisoning.

METHODS

We did a community-based, cluster-randomised controlled trial in a rural area of North Central Province, Sri Lanka. Clusters of households were randomly assigned (1:1), with a sequence computer-generated by a minimisation process, to intervention or usual practice (control) groups. Intervention households that had farmed or had used or stored pesticide in the preceding agricultural season were given a lockable storage container. Further promotion of use of the containers was restricted to community posters and 6-monthly reminders during routine community meetings. The primary outcome was incidence of pesticide self-poisoning in people aged 14 years or older during 3 years of follow-up. Identification of outcome events was done by staff who were unaware of group allocation. Analysis was by intention to treat. This trial is registered with ClinicalTrials.gov, number NCT1146496.

FINDINGS

Between Dec 31, 2010, and Feb 2, 2013, we randomly assigned 90 rural villages to the intervention group and 90 to the control group. 27 091 households (114 168 individuals) in the intervention group and 26 291 households (109 693 individuals) in the control group consented to participate. 20 457 household pesticide storage containers were distributed. In individuals aged 14 years or older, 611 cases of pesticide self-poisoning had occurred by 3 years in the intervention group compared with 641 cases in the control group; incidence of pesticide self-poisoning did not differ between groups (293·3 per 100 000 person-years of follow-up in the intervention group vs 318·0 per 100 000 in the control group; rate ratio [RR] 0·93, 95% CI 0·80-1·08; p=0·33). We found no evidence of switching from pesticide self-poisoning to other forms of self-harm, with no significant difference in the number of fatal (82 in the intervention group vs 67 in the control group; RR 1·22, 0·88-1·68]) or non-fatal (1135 vs 1153; RR 0·97, 0·86-1·08) self-harm events involving all methods.

INTERPRETATION

We found no evidence that means reduction through improved household pesticide storage reduces pesticide self-poisoning. Other approaches, particularly removal of highly hazardous pesticides from agricultural practice, are likely to be more effective for suicide prevention in rural Asia.

FUNDING

Wellcome Trust, with additional support from the American Foundation for Suicide Prevention, Lister Institute of Preventive Medicine, Chief Scientist Office of Scotland, University of Copenhagen, and NHMRC Australia.

Activated charcoal significantly reduces the amount of colchicine released from Gloriosa superba in simulated gastric and intestinal media

BACKGROUND

Poisoning with Gloriosa superba, a plant containing colchicine, is common in Sri Lanka.

OBJECTIVES

This study was to estimate release of colchicine from 5 g of different parts of Gloriosa superba in simulated gastric and intestinal media, and examine the binding efficacy of activated charcoal (AC) to colchicine within this model.

METHODS

A USP dissolution apparatus-II was used to prepare samples for analysis of colchicine using HPLC.

RESULTS

Cumulative colchicine release from tuber in gastric media at 120 minutes was significantly higher (2883 μg/g) than in intestinal media (1015 μg/g) (p < .001). Mean ± SD cumulative colchicine concentration over 2 hours from tuber, leaves and trunk in gastric medium was 2883.15 ± 1295.63, 578.25 ± 366.26 and 345.60 ± 200.08 μg/g respectively and the release in intestinal media was 1014.75 ± 268.16, 347.40 ± 262.61 and 251.55 ± 285.72 μg/g respectively. Introduction of 50 g of AC into both media made colchicine undetectable (<0.1 μg/ml).

CONCLUSIONS

The tuber released the highest quantity of colchicine. The colchicine release and elapse time to achieve saturated, equilibrium dissolution mainly depends on physicochemical properties of plant part. Significant in vitro binding of colchicine to AC suggests that AC has a role in decontamination of patients presenting to hospital after ingestion of Gloriosa superba.

Nephrotoxicity-induced proteinuria increases biomarker diagnostic thresholds in acute kidney injury

BACKGROUND

Paraquat ingestion is frequently fatal. While biomarkers of kidney damage increase during paraquat-induced acute kidney injury (AKI), significant concurrent proteinuria may alter diagnostic thresholds for diagnosis and prognosis to an unknown extent. This study evaluated the effect of albuminuria on biomarker cutoffs for diagnosis and outcome prediction.

METHODS

This was a multi-centre prospective clinical study of patients following acute paraquat self-poisoning in 5 Sri Lankan hospitals. Biomarker concentrations were quantified using ELISA and microbead assays and correlated with urinary albumin. Functional-AKI was defined by the Acute Kidney Injury Network serum creatinine definition and alternatively by a ≥50% increase in serum cystatin C. Albuminuria was defined as albumin-creatinine ratio >30 mg/g. The study outcomes were compared with a retrospective analysis of a pre-clinical study of paraquat-induced nephrotoxicity with appropriate controls.

RESULTS

Albuminuria was detected in 34 of 50 patients, and increased with functional-AKI severity. The concentrations of uNGAL, uCysC, uClusterin, uβ2M, and uKIM-1 were higher in albuminuric compared to non-albuminuric patients (p < 0.001). Albuminuria correlated with biomarker concentration (r > 0.6, p < 0.01) and was associated with death (p = 0.006). Optimal biomarker cutoffs for prediction of death were higher in the albuminuric group. Similar outcomes with more detailed analysis were obtained in experimental paraquat nephrotoxicity.

CONCLUSION

Albuminuria was associated with paraquat-induced nephrotoxicity and increased excretion of low-molecular weight protein biomarkers. AKI biomarker cutoffs for diagnosis, outcome prediction and AKI stratification increased in the presence of albuminuria. This may lead to over-diagnosis of AKI in conditions independently associated with proteinuria.

A randomized controlled trial of fresh frozen plasma for coagulopathy in Russell's viper (Daboia russelii) envenoming

Essentials Russell's viper envenoming is a major health issue in South Asia and causes coagulopathy. We studied the effect of fresh frozen plasma and two antivenom doses on correcting coagulopathy. Fresh frozen plasma did not hasten recovery of coagulopathy. Low-dose antivenom did not worsen coagulopathy.

SUMMARY

Background Russell's viper (Daboia russelii) envenoming is a major health issue in South Asia and causes venom-induced consumption coagulopathy (VICC). Objectives To investigate the effects of fresh frozen plasma (FFP) and two antivenom doses in correcting VICC. Methods We undertook an open-label randomized controlled trial in patients with VICC at two Sri Lankan hospitals. Patients with suspected Russell's viper bites and coagulopathy were randomly allocated (1 : 1) to high-dose antivenom (20 vials) or low-dose antivenom (10 vials) plus 4 U of FFP. The primary outcome was the proportion of patients with an International Normalized Ratio (INR) of < 2 at 6 h after antivenom administration. Secondary outcomes included anaphylaxis, major hemorrhage, death, and clotting factor recovery. Results From 214 eligible patients, 141 were randomized: 71 to high-dose antivenom, and 70 to low-dose antivenom/FFP; five had no post-antivenom blood tests. The groups were similar except for a delay of 1 h in antivenom administration for FFP patients. Six hours after antivenom administration, 23 of 69 (33%) patients allocated to high-dose antivenom had an INR of < 2, as compared with 28 of 67 (42%) allocated to low-dose antivenom/FFP (absolute difference 8%; 95% confidence interval - 8% to 25%). Fifteen patients allocated to FFP did not receive it. Severe anaphylaxis occurred equally frequently in each group. One patient given FFP developed transfusion-related acute lung injury. Three deaths occurred in low-dose antivenom/FFP patients, including one intracranial hemorrhage. There was no difference in recovery rates of INR or fibrinogen, but there was more rapid initial recovery of factor V and FX in FFP patients. Conclusion FFP after antivenom administration in patients with Russell's viper bites did not hasten recovery of coagulopathy. Low-dose antivenom/FFP did not worsen VICC, suggesting that low-dose antivenom is sufficient.

Is socioeconomic position associated with risk of attempted suicide in rural Sri Lanka? A cross-sectional study of 165 000 individuals

BACKGROUND

Lower socioeconomic position (SEP) is associated with an increased risk of suicidal behaviour in high-income countries, but this association is unclear in low-income and middle-income countries.

METHODS

We investigated the association of SEP with attempted suicide in a cross-sectional survey of 165 233 Sri Lankans. SEP data were collected at the household (assets, social standing (highest occupation of a household member), foreign employment and young (≤40 years) female-headed households) and individual level (education and occupation). Respondent-reported data on suicide attempts in the past year were recorded. Random-effects logistic regression models, accounting for clustering, were used to investigate the association of SEP with attempted suicide.

RESULTS

Households reported 398 attempted suicides in the preceding year (239 per 100 000). Fewer assets (OR 3.2, 95% CI 2.4 to 4.4) and having a daily wage labourer (ie, insecure/low-income job; OR 2.3, 95% CI 1.6 to 3.2) as the highest occupation increased the risk of an attempted suicide within households. At an individual level, daily wage labourers were at an increased risk of attempted suicide compared with farmers. The strongest associations were with low levels of education (OR 4.6, 95% CI 2.5 to 8.4), with a stronger association in men than women.

CONCLUSIONS

We found that indicators of lower SEP are associated with increased risk of attempted suicide in rural Sri Lanka. Longitudinal studies with objective measures of suicide attempts are needed to confirm this association.

TRIAL REGISTRATION NUMBER

NCT01146496; Pre-results.

Mechanism-specific injury biomarkers predict nephrotoxicity early following glyphosate surfactant herbicide (GPSH) poisoning

Acute kidney injury (AKI) is common following glyphosate surfactant herbicide (GPSH) self-poisoning. Serum creatinine (sCr) is the most widely used renal biomarker for diagnosis of AKI although a recent study in rats suggested that urinary kidney injury molecule-1 predicted AKI earlier and better after GPSH-induced nephrotoxicity. We explored the utility of a panel of biomarkers to diagnose GPSH-induced nephrotoxicity in humans. In a prospective multi-centre observational study, serial urine and blood samples were collected until discharge and at follow-up. The diagnostic performance of each biomarker at various time points was assessed. AKI was diagnosed using the Acute Kidney Injury Network (AKIN) definitions. The added value of each biomarker to sCr to diagnose AKI was assessed by the integrated discrimination improvement (IDI) metric. Of 90 symptomatic patients, 51% developed AKI and 5 patients who developed AKIN≥2 died. Increased sCr at 8 and 16h predicted moderate to severe AKI and death. None of the 10 urinary biomarkers tested increased above normal range in patients who did not develop AKI or had mild AKI (AKIN1); most of these patients also had only minor clinical toxicity. Absolute concentrations of serum and urinary cystatin C, urinary interleukin-18 (IL-18), Cytochrome C (CytoC) and NGAL increased many fold within 8h in patients who developed AKIN≥2. Maximum 8 and 16h concentrations of these biomarkers showed an excellent diagnostic performance (AUC-ROC ≥0.8) to diagnose AKIN≥2. However, of these biomarkers only uCytoC added value to sCr to diagnose AKI when assessed by IDI metrics. GPSH-induced nephrotoxicity can be diagnosed within 24h by sCr. Increases in uCytoC and uIL-18 confirm GPSH-induces apoptosis and causes mitochondrial toxicity. Use of these biomarkers may help to identify mechanism specific targeted therapies for GPSH nephrotoxicity in clinical trials.

High lethality and minimal variation after acute self-poisoning with carbamate insecticides in Sri Lanka - implications for global suicide prevention

Background: Highly hazardous organophosphorus (OP) insecticides are responsible for most pesticide poisoning deaths. As they are removed from agricultural practice, they are often replaced by carbamate insecticides of perceived lower toxicity. However, relatively little is known about poisoning with these insecticides.

Methods: We prospectively studied 1288 patients self-poisoned with carbamate insecticides admitted to six Sri Lankan hospitals. Clinical outcomes were recorded for each patient and plasma carbamate concentration measured in a sample to confirm the carbamate ingested.

Findings: Patients had ingested 3% carbofuran powder (719), carbosulfan EC25 liquid (25% w/v, 389), or fenobucarb EC50 liquid (50% w/v, 127) formulations, carbamate insecticides of WHO Toxicity Classes Ib, II, and II, respectively. Intubation and ventilation was required for 183 (14.2%) patients while 71 (5.5%) died. Compared with carbofuran, poisoning with carbosulfan or fenobucarb was associated with significantly higher risk of death [carbofuran 2.2%; carbosulfan 11.1%, OR 5.5 (95% CI 3.0–9.8); fenobucarb 6.3%, OR 3.0 (1.2–7.1)] and intubation [carbofuran 6.1%; carbosulfan 27.0%, OR 5.7 (3.9–8.3); fenobucarb 18.9%, OR 3.6 (2.1–6.1)]. The clinical presentation and cause of death did not differ markedly between carbamates. Median time to death was similar: carbofuran 42.3 h (IQR 5.5–67.3), carbosulfan 21.3 h (11.5–71.3), and fenobucarb 25.3 h (17.3–72.1) (p = 0.99); no patients showed delayed onset of toxicity akin to the intermediate syndrome seen after OP insecticide poisoning. For survivors, median duration of intubation was 67.8 h (IQR 27.5–118.8) with no difference in duration between carbamates. Reduced GCS at presentation was associated with worse outcome although some patients with carbosulfan died after presentation with normal GCS.

Conclusions: We did not find carbamate insecticide self-poisoning to vary markedly according to the carbamate ingested although the case fatality varied according to the concentration and formulation of the insecticide. Carbamate poisoning did not appear to be much less toxic than poisoning with some liquid OP insecticide formulations, e.g., chlorpyrifos EC40, that we have previously noted in these same hospitals (Lancet 2005, 366:1452–1459; QJM 2006, 99:513–522). Replacement of WHO Class II Toxicity OP insecticides in agriculture with high-strength liquid carbamate formulations may not substantially reduce case fatality after pesticide poisoning and, therefore, global suicide rates.

Prediction of paraquat exposure and toxicity in clinically ill poisoned patients: a model based approach

AIMS

Paraquat poisoning is a medical problem in many parts of Asia and the Pacific. The mortality rate is extremely high as there is no effective treatment. We analyzed data collected during an ongoing cohort study on self-poisoning and from a randomized controlled trial assessing the efficacy of immunosuppressive therapy in hospitalized paraquat-intoxicated patients. The aim of this analysis was to characterize the toxicokinetics and toxicodynamics of paraquat in this population.

METHODS

A non-linear mixed effects approach was used to perform a toxicokinetic/toxicodynamic population analysis in a cohort of 78 patients.

RESULTS

The paraquat plasma concentrations were best fitted by a two compartment toxicokinetic structural model with first order absorption and first order elimination. Changes in renal function were used for the assessment of paraquat toxicodynamics. The estimates of toxicokinetic parameters for the apparent clearance, the apparent volume of distribution and elimination half-life were 1.17 l h(-1) , 2.4 l kg(-1) and 87 h, respectively. Renal function, namely creatinine clearance, was the most significant covariate to explain between patient variability in paraquat clearance.This model suggested that a reduction in paraquat clearance occurred within 24 to 48 h after poison ingestion, and afterwards the clearance was constant over time. The model estimated that a paraquat concentration of 429 μg l(-1) caused 50% of maximum renal toxicity. The immunosuppressive therapy tested during this study was associated with only 8% improvement of renal function.

CONCLUSION

The developed models may be useful as prognostic tools to predict patient outcome based on patient characteristics on admission and to assess drug effectiveness during antidote drug development.

Population Pharmacokinetics of an Indian F(ab')2 Snake Antivenom in Patients with Russell's Viper (Daboia russelii) Bites

BACKGROUND

There is limited information on antivenom pharmacokinetics. This study aimed to investigate the pharmacokinetics of an Indian snake antivenom in humans with Russell's viper bites.

METHODS/PRINCIPAL FINDINGS

Patient data and serial blood samples were collected from patients with Russell's viper (Daboia russelii) envenoming in Sri Lanka. All patients received Indian F(ab')2 snake antivenom manufactured by VINS Bioproducts Ltd. Antivenom concentrations were measured with sandwich enzyme immunoassays. Timed antivenom concentrations were analysed using MONOLIXvs4.2. One, two and three compartment models with zero order input and first order elimination kinetics were assessed. Models were parameterized with clearance (CL), intercompartmental clearance (Q), central compartment volume (V) and peripheral compartment volume (VP). Between-subject-variability (BSV) on relative bioavailability (F) was included to account for dose variations. Covariates effects (age, sex, weight, antivenom batch, pre-antivenom concentrations) were explored by visual inspection and in model building. There were 75 patients, median age 57 years (40-70 y) and 64 (85%) were male. 411 antivenom concentration data points were analysed. A two compartment model with zero order input, linear elimination kinetics and a combined error model best described the data. Inclusion of BSV on F and weight as a covariate on V improved the model. Inclusion of pre-antivenom concentrations or different batches on BSV of F did not. Final model parameter estimates were CL,0.078 L h(-1), V,2.2L, Q,0.178 L h(-1) and VP,8.33L. The median half-life of distribution was 4.6 h (10-90%iles:2.6-7.1 h) and half-life of elimination, 140 h (10th-90th percentilesx:95-223h).

CONCLUSION

Indian F(ab')2 snake antivenom displayed biexponential disposition pharmacokinetics, with a rapid distribution half-life and more prolonged elimination half-life.

Epidemiology and clinical effects of hump-nosed pit viper (Genus: Hypnale) envenoming in Sri Lanka

Hump-nosed pit vipers of Genus Hypnale are the commonest cause of snake bite in Sri Lanka. Although there are many reports of local effects, coagulopathy and acute kidney injury, it remains unclear how frequent these clinical effects are and therefore the medical importance of this snake genus. The genus has been recently revised to include Hypnale hypnale from Sri Lanka and Western Ghats of Southern India, and the two endemic species to Sri Lanka, Hypnale zara and Hypnale nepa. This was a prospective hospital-based clinical study of definite Hypnale spp. bites from July 2008 to July 2010 in six Sri Lankan hospitals. There were 114 patients included and all snakes were correctly identified by hospital staff as Hypnale spp. Of these, 93 snakes were identified as H. hypnale by an expert, 16 as H. zara and five as H. nepa. Most bites occurred on the lower limbs in the daytime. There was no difference in the clinical effects between the three species. Pain and fang marks were present in all patients, 101 had local swelling and only 16 (14%) developed extensive local swelling that spread proximally and involved more than half of the bitten limb. Systemic symptoms occurred in 18 patients; four patients had an abnormal 20 min whole blood clotting test and one patient developed an acute kidney injury that required haemodialysis. All patients were discharged alive with a median length of stay of 2 days. This study confirms that hump-nosed viper bites cause only minor effects in most cases. Future studies need to undertake formal coagulation studies and identify important early indicators of renal impairment.

Comparative in-vivo toxicity of venoms from South Asian hump-nosed pit vipers (Viperidae: Crotalinae: Hypnale)

Background

Envenoming by south Asian hump-nosed pit vipers (Genus: Hypnale) is a significant health issue in Sri Lanka and in peninsular India. Bites by these snakes frequently lead to local envenoming, coagulopathy and acute renal failure even resulting in death. Recently the genus was revised and the existence of three species viz H. hypnale, H. nepa and H. zara were recognized. There is, however, a paucity of information on the toxicity of the venoms of these species. Hence, we compared the toxic effects of the three Hypnale venoms using BALB/c mice.

Findings

Intraperitoneal median lethal doses (LD₅₀) for H. hypnale, H. zara and H. nepa venoms were 1.6, 6.0 and 9.5 μg protein/g respectively. Minimum haemorrhagic doses for venoms of H. hypnale, H. zara and H. nepa were 3.4, 11.0 and 16.6 μg protein/mouse respectively. The minimum necrotic doses for the same venoms were 15.0, 55.1 and 68.2 μg protein/mouse respectively. Severe congestion and petecheal haemorrhages were observed in lungs, kidneys, liver and the alimentary tract. Histopathogical examination of kidneys revealed proximal tubular cell injury and acute tubular necrosis with intact basement membrane indicating possible direct nephrotoxicity. Hypnale venoms caused pulmonary oedema, hepatocellular degeneration and necrosis, focal neuronal degeneration in brain and extramedullary haemopoiesis in spleen. H. hypnale venom caused all above histopathological alterations at lower doses compared to the other two.

Conclusion

Hypnale venoms cause similar pathological changes with marked differences in the severity of the toxic effects in vivo. Therefore, differences in the severity of the clinical manifestations could possibly be seen among bite victims of the three Hypnale species.

A community-based cluster randomised trial of safe storage to reduce pesticide self-poisoning in rural Sri Lanka: study protocol

Background

The WHO recognises pesticide poisoning to be the single most important means of suicide globally. Pesticide self-poisoning is a major public health and clinical problem in rural Asia, where it has led to case fatality ratios 20-30 times higher than self-poisoning in the developed world. One approach to reducing access to pesticides is for households to store pesticides in lockable "safe-storage" containers. However, before this approach can be promoted, evidence is required on its effectiveness and safety.

Methods/Design

A community-based cluster randomised controlled trial has been set up in 44,000 households in the North Central Province, Sri Lanka. A census is being performed, collecting baseline demographic data, socio-economic status, pesticide usage, self-harm and alcohol. Participating villages are then randomised and eligible households in the intervention arm given a lockable safe storage container for agrochemicals.

The primary outcome will be incidence of pesticide self-poisoning over three years amongst individuals aged 14 years and over. 217,944 person years of follow-up are required in each arm to detect a 33% reduction in pesticide self-poisoning with 80% power at the 5% significance level. Secondary outcomes will include the incidence of all pesticide poisoning and total self-harm.

Discussion

This paper describes a large effectiveness study of a community intervention to reduce the burden of intentional poisoning in rural Sri Lanka. The study builds on a strong partnership between provincial health services, local and international researchers, and local communities. We discuss issues in relation to randomisation and contamination, engaging control villages, the intervention, and strategies to improve adherence.

Trial Registritation

The trial is registered on ClinicalTrials.gov ref: NCT1146496 (http://clinicaltrialsfeeds.org/clinical-trials/show/NCT01146496).

Simple and sensitive liquid chromatography-tandem mass spectrometry methods for quantification of paraquat in plasma and urine: application to experimental and clinical toxicological studies

Simple, sensitive and specific liquid chromatography-tandem mass spectrometry (LC-MS/MS) methods have been developed and validated for quantification of paraquat (PQ) in plasma and urine. Plasma and urine sample preparation were carried out by one-step protein precipitation using cold acetonitrile (-20 to -10 °C). After centrifugation, an aliquot of 10 μL of supernatant was injected into a Kinetex™ hydrophilic interaction chromatography (HILIC) column with a KrudKatcher™ Ultra in-line filter. The chromatographic separation was achieved using the mobile phase mixture of 250 mM ammonium formate (with 0.8% aqueous formic acid) in water and acetonitrile at a flow rate of 0.3 mL/min. Detection was performed using an API2000 triple quadrupole tandem mass spectrometer in multiple reaction monitoring (MRM) mode via an electrospray ionization (ESI) source. The calibration curve was linear over the concentration range of 10-5000 ng/mL, with an LLOQ of 10 ng/mL. The inter- and intra-day precision (% R.S.D.) were <8.5% and 6.4% for plasma and urine, respectively with the accuracies (%) within the range of 95.1-102.8%. PQ in plasma and urine samples was stable when stored at -70 °C for three freeze-thaw cycles. The methods were successfully applied to determine PQ concentration in rat and human samples.

The in vitro toxicity of venoms from South Asian hump-nosed pit vipers (Viperidae: Hypnale)

Hump-nosed pit vipers (Genus Hypnale) are venomous snakes from South India and Sri Lanka. Envenoming by Hypnale species may cause significant morbidity and is characterized by local envenoming and less commonly coagulopathy and acute renal failure. Currently there are three nominal species of this genus: H. hypnale, H. zara and H. nepa. This study investigates the biochemical and pharmacological properties of the venoms from the three Hypnale species in Sri Lanka. The three Hypnale venoms had similar chromatographic profiles using reverse phase high performance liquid chromatography and fractions with procoagulant activity were identified. Hypnale venoms had potent cytotoxicity in cultured rat aorta smooth muscle cells with similar IC(50) values. The venoms had weak neurotoxic and myotoxic activity in the isolated chick biventer muscle preparation. They had mild procoagulant activity with close MCC(5) values and also phospholipase activity. Locally available polyvalent antivenom did not neutralise any venom effects. The study demonstrates that the three Hypnale venoms are similar and cytotoxicity appears to be the most potent effect, although they have mild procoagulant activity. These findings are consistent with clinical reports.

Acute human lethal toxicity of agricultural pesticides: a prospective cohort study

BACKGROUND

agricultural pesticide poisoning is a major public health problem in the developing world, killing at least 250,000-370,000 people each year. Targeted pesticide restrictions in Sri Lanka over the last 20 years have reduced pesticide deaths by 50% without decreasing agricultural output. However, regulatory decisions have thus far not been based on the human toxicity of formulated agricultural pesticides but on the surrogate of rat toxicity using pure unformulated pesticides. We aimed to determine the relative human toxicity of formulated agricultural pesticides to improve the effectiveness of regulatory policy.

METHODS AND FINDINGS

we examined the case fatality of different agricultural pesticides in a prospective cohort of patients presenting with pesticide self-poisoning to two clinical trial centers from April 2002 to November 2008. Identification of the pesticide ingested was based on history or positive identification of the container. A single pesticide was ingested by 9,302 patients. A specific pesticide was identified in 7,461 patients; 1,841 ingested an unknown pesticide. In a subset of 808 patients, the history of ingestion was confirmed by laboratory analysis in 95% of patients. There was a large variation in case fatality between pesticides-from 0% to 42%. This marked variation in lethality was observed for compounds within the same chemical and/or WHO toxicity classification of pesticides and for those used for similar agricultural indications.

CONCLUSION

the human data provided toxicity rankings for some pesticides that contrasted strongly with the WHO toxicity classification based on rat toxicity. Basing regulation on human toxicity will make pesticide poisoning less hazardous, preventing hundreds of thousands of deaths globally without compromising agricultural needs. Ongoing monitoring of patterns of use and clinical toxicity for new pesticides is needed to identify highly toxic pesticides in a timely manner.

Fructose-1, 6-diphosphate (FDP) as a novel antidote for yellow oleander-induced cardiac toxicity: a randomized controlled double blind study

BACKGROUND

Cardiac toxicity due to ingestion of oleander plant seeds in Sri Lanka and some other South Asian countries is very common. At present symptomatic oleander seed poisoning carries a mortality of 10% in Sri Lanka and treatment of yellow oleander poisoning is limited to gastric decontamination and atropine administration. The only proven effective antidote is digoxin antibodies but these are not available for routine use because of the high cost. The main objective of this study is to investigate the effectiveness of a new and inexpensive antidote for patients with life threatening arrhythmias due oleander poisoning.

METHOD/DESIGN

We set up a randomised double blind clinical trial to assess the effectiveness of Fructose 1, 6 diphosphate (FDP) in acute yellow oleander poisoning patients admitted to the adult medical wards of a tertiary hospital in Sri Lanka. Patients will be initially resuscitated following the national guidelines and eligible patients will be randomised to receive either FDP or an equal amount of normal saline. The primary outcome measure for this study is the sustained reversion to sinus rhythm with a heart rate greater than 50/min within 2 hours of completion of FDP/placebo bolus. Secondary outcomes include death, reversal of hyperkalaemia on the 6, 12, 18 and 24 hour samples and maintenance of sinus rhythm on the holter monitor. Analysis will be on intention-to-treat.

DISCUSSION

This trial will provide information on the effectiveness of FDP in yellow oleander poisoning. If FDP is effective in cardiac glycoside toxicity, it would provide substantial benefit to the patients in rural Asia. The drug is inexpensive and thus could be made available at primary care hospitals if proven to be effective.

TRIAL REGISTRATION

Current Controlled trial ISRCTN71018309.

Acute intentional self-poisoning with a herbicide product containing fenoxaprop-P-ethyl, ethoxysulfuron, and isoxadifen ethyl: a prospective observational study

BACKGROUND

Herbicides are commonly ingested for self-harm, but relatively little has been published on poisoning with herbicides other than paraquat and glyphosate. We report here a case series of patients with acute exposure to a combination herbicide (brand name Tiller Gold or Whip Super) containing the selective phenoxy herbicide compounds fenoxaprop-P-ethyl and ethoxysulfuron and a safener isoxadifen ethyl.

METHOD

Clinical data on all patients presenting with Tiller Gold or Whip Super poisoning to two General Hospitals in Sri Lanka from 2002-2008 were collected prospectively until discharge.

RESULTS

Eighty-six patients with a history of Tiller Gold or Whip Super ingestion were included. The main clinical features were an epigastric burning sensation and vomiting; however, most of those who vomited had received gastric lavage or forced emesis. Eight patients had a reduced level of consciousness on admission (Glasgow coma scale 9-14) that resolved without intervention over several hours. Only symptomatic and supportive care was required. The median hospital stay was 1 day (IQR: 1-2) and the case fatality was zero (95% confidence interval: 0-4.2%). This low case fatality compared favorably with the case fatality of other common herbicides in our cohort: paraquat >40%, propanil >10%, 4-chloro-2-methylphenoxyacetic acid > 5%, and glyphosate >2%.

CONCLUSION

This combination herbicide product appears to be safe in patients with acute self-poisoning, particularly in comparison with other herbicides, and causing few clinical features.

Systematic review of controlled clinical trials of gastric lavage in acute organophosphorus pesticide poisoning

BACKGROUND

Organophosphorus pesticide (OP) self-poisoning is a major problem in the developing rural world. There is little clinical trial data to guide therapy, hindering the identification of best therapy. Despite the recognition of adverse effects, gastric lavage is commonly done in Asia. We aimed to identify studies assessing its effectiveness.

METHOD

We systematically searched the literature for controlled clinical studies that assessed the effect of gastric lavage in OP pesticide self-poisoning.

RESULTS

All 56 studies identified were Chinese and reported benefit from the intervention studied, including multiple gastric lavages, use of norepinephrine or pralidoxime in the lavage fluid, concurrent treatment with naloxone or scopolamine, insertion of the gastric tube via a laparotomy incision, and lavage later than 12 h post-ingestion. However, only 23 were RCTs and none presented adequate methodology for their quality to be assessed. The patient population and study treatment protocol were not defined - large variation in case fatality in the control arm of the studies (from 4.5 to 93%) suggests marked variation between studies and likely between study arms. No study compared an intervention against a control group receiving no gastric lavage or provided any data to indicate whether a significant quantity of poison was removed.

CONCLUSION

Despite widespread use of multiple gastric lavages for OP pesticide poisoning across Asia, there is currently no high-quality evidence to support its clinical effectiveness. There is a need for studies to identify in which patients and for what duration gastric lavage is able to remove significant quantities of poison. Following these studies, large clinical trials will be required to address the effectiveness and safety of gastric lavage (either single or multiple) in acute OP pesticide poisoning.

Acute human self-poisoning with imidacloprid compound: a neonicotinoid insecticide

Background

Deliberate self-poisoning with older pesticides such as organophosphorus compounds are commonly fatal and a serious public health problem in the developing world. The clinical consequences of self-poisoning with newer pesticides are not well described. Such information may help to improve clinical management and inform pesticide regulators of their relative toxicity. This study reports the clinical outcomes and toxicokinetics of the neonicotinoid insecticide imidacloprid following acute self-poisoning in humans.

Methodology/Principal Findings

Demographic and clinical data were prospectively recorded in patients with imidacloprid exposure in three hospitals in Sri Lanka. Blood samples were collected when possible for quantification of imidacloprid concentration. There were 68 patients (61 self-ingestions and 7 dermal exposures) with exposure to imidacloprid. Of the self-poisoning patients, the median time to presentation was 4 hours (IQR 2.3–6.0) and median amount ingested was 15 mL (IQR 10–50 mL). Most patients only developed mild symptoms such as nausea, vomiting, headache and diarrhoea. One patient developed respiratory failure needing mechanical ventilation while another was admitted to intensive care due to prolonged sedation. There were no deaths. Median admission imidacloprid concentration was 10.58 ng/L; IQR: 3.84–15.58 ng/L, Range: 0.02–51.25 ng/L. Changes in the concentration of imidacloprid in serial blood samples were consistent with prolonged absorption and/or saturable elimination.

Conclusions

Imidacloprid generally demonstrates low human lethality even in large ingestions. Respiratory failure and reduced level of consciousness were the most serious complications, but these were uncommon. Substitution of imidacloprid for organophosphorus compounds in areas where the incidence of self-poisoning is high may help reduce deaths from self-poisoning.