Fatal and non-fatal methomyl intoxication in an attempted double suicide

Pesticide use, agricultural outputs, and pesticide poisoning deaths in Japan

OBJECTIVE

Although pesticide poisonings occur worldwide, most high-income countries have not been severely affected. Japan is a key exception, with pesticide suicides becoming a major public health concern in the 1980s. We here report the epidemiology of lethal pesticide poisoning in Japan in relation to its pesticide regulation and agricultural output.

METHODS

We obtained data on pesticide registration and sales from the Japan Plant Protection Association's annual Pesticide Handbook, National Food and Agricultural Materials Inspection Center, and Food and Agriculture Organization of the United Nations. Data on deaths due to pesticide poisoning and population were obtained from Vital Statistics of Japan. We reviewed the registration status and hazard classification of pesticides in Japan and analysed the relationships between the use/sales, pesticides fatalities, and agricultural output.

RESULTS

Five hundred and twenty-nine pesticide active ingredients are currently registered in Japan, including four WHO hazard class IB organophosphorus and carbamate insecticides. Paraquat was registered in 1962 as a liquid SL20 formulation. In 1986, restrictions were imposed on its sale/use and a 4.3% paraquat ion/4.1% diquat ion combination product registered by ICI. There were 221 pesticide poisoning fatalities in 2019, down from 2648 in 1986, a 92% reduction over 33 years. Self-poisoning was responsible for most pesticide deaths in both 1985 (2013/2476, 81.3%) and 2019 (146/221, 66.1%). Pesticide poisoning made up 8.6% of all suicides in 1985, down to 0.7% in 2019. Unintentional pesticide poisoning deaths also all fell by 83.8%, from 463 to 75. These reductions were associated with reduced sales of both OP/carbamate insecticides and paraquat/diquat but no apparent change in agricultural output across a broad range of crops.

CONCLUSIONS

Reduced use of highly hazardous pesticides and lowered concentration formulations in Japan were associated with major decreases in all deaths from pesticide poisoning and the proportion of all suicides due to pesticide ingestion.

The Lethal Cutting: An Unexpected Cause of Death

Cocaine is among the illicit substances most frequently implicated in deaths related to the use of drugs of abuse both worldwide and in Italy. Cutting agents involved in the adulterations of this substance are many and the process of lacing can take place at various stages of the production of the drug. In this Report we are discussing the case of a 27-year-old woman found death next to her car in a wooded area in the suburban area of Milan. On the crime scene, several specimens of white powder were collected and subsequently analyzed via Q-Exactive Orbitrap with a HPLC system and LC/MS-MS analysis along with biological matrices sampled during autopsy examination. The toxicological analysis revealed that the death could be ascribed to a lethal dose of methomyl, a carbamide pesticide used as cutting agent for cocaine. According to Literature, this is the first time that this substance is used as an adulterant.

Methomyl induced effect on fortilin and S100A1 in serum and cardiac tissue: Potential biomarkers of toxicity

Methomyl toxicity has been reported as a cause of several accidental and suicidal fatalities. The study is evaluating the effect of lethal methomyl toxicity on fortilin and S100A1 in serum and cardiac tissues. Adult 96 female Sprague-Dawley rats were divided equally into a control (euthanized by cervical dislocation) and a study group (overdosed with methomyl). The levels of fortilin and S100A1 in serum were measured antemortem (to establish the basal levels in serum) and postmortem (to evaluate changes after methomyl exposure) using enzyme-linked immunoassay. S100A1 was immunostained in sections from cardiac tissues. Both proteins in the control were not significantly different ( p > 0.05) compared with the antemortem levels. On the contrast, both biomarkers levels in the intoxicated group were remarkably higher ( p < 0.001) than the control and the antemortem levels. Ventricular tissues from the intoxicated rats presented depleted S100A1 immunostain in cardiomyocytes localized mainly in the epicardium with deeply stained adjacent cardiac fibroblasts. The cardiomyocytes were damaged with a prominent loss of striations compared to normal cardiac tissues from the control. The present outcomes explain to a certain degree the potential toxic effect of methomyl poisoning on the cardiac tissue. Both proteins could be added to the currently available battery of markers for assessing methomyl toxicity.

Organophosphorus and carbamate insecticide poisoning

Both organophosphorus (OP) and carbamate insecticides inhibit acetylcholinesterase (AChE), which results in accumulation of acetylcholine (ACh) at autonomic and some central synapses and at autonomic postganglionic and neuromuscular junctions. As a consequence, ACh binds to, and stimulates, muscarinic and nicotinic receptors, thereby producing characteristic features. With OP insecticides (but not carbamates), "aging" may also occur by partial dealkylation of the serine group at the active site of AChE; recovery of AChE activity requires synthesis of new enzyme in the liver. Relapse after apparent resolution of cholinergic symptoms has been reported with OP insecticides and is termed the intermediate syndrome. This involves the onset of muscle paralysis affecting particularly upper-limb muscles, neck flexors, and cranial nerves some 24-96 hours after OP exposure and is often associated with the development of respiratory failure. OP-induced delayed neuropathy results from phosphorylation and subsequent aging of at least 70% of neuropathy target esterase. Cramping muscle pain in the lower limbs, distal numbness, and paresthesiae are followed by progressive weakness, depression of deep tendon reflexes in the lower limbs and, in severe cases, in the upper limbs. The therapeutic combination of oxime, atropine, and diazepam is well established experimentally in the treatment of OP pesticide poisoning. However, there has been controversy as to whether oximes improve morbidity and mortality in human poisoning. The explanation may be that the solvents in many formulations are primarily responsible for the high morbidity and mortality; oximes would not be expected to reduce toxicity in these circumstances. even if given in appropriate dose.

Determination of methomyl in the stomach contents of baited wildlife by gas chromatography–mass spectrometry

The poisoning of wildlife with fly-bait containing the active ingredient methomyl is an intentional and illegal act in many jurisdictions. A case of 2 animals poisoned by methomyl through consumption of tainted bait at multiple stations is described. Although thermally and ultraviolet-labile, methomyl can be identified by gas chromatography–mass spectrometry and is detected in abundance in bait samples; however, it is not readily observed in tissues, owing to its rapid metabolism and elimination. The application of derivatizing functionalities, such as trimethylsilyl groups, stabilizes the methomyl-oxime metabolite to facilitate its detectability during exposure to the relatively harsh conditions of gas chromatography. This brief communication reports on the analytical detection of methomyl in baits and biological samples from poisoned wildlife. Essential to the case were the added determination of a fly-bait coactive ingredient, ( Z)-9-tricosene, and identification of a chemical indicator, caffeine, to confirm both the type of pesticide product involved in the poisoning incident and the vehicle used to perpetrate its delivery.

Environmental fate and toxicology of methomyl

The insecticide methomyl, an oxime carbamate, was first introduced in 1968 for broad spectrum control of several insect classes, including Lepidoptera, Hemiptera, Homoptera, Diptera, and Coleoptera. Like other carbamates, it inhibits AChE activity, resulting in nerve and/or tissue failure and possibly death. Considered highly toxic to insects (larval and adult stages), methomyl is thought to be metabolically degraded via mixed-function oxidase(s). Methomyl has both a low vapor pressure and Henry's law constant; hence, volatilization is not a major dissipation route from either water or moist or dry soils. Photolysis represents a minor dissipation pathway; however, under catalytic conditions, degradation via photolysis does occur. Methomyl possesses a moderate-to-high water solubility; thus hydrolysis, under alkaline conditions, represents a major degradation pathway. Methomyl has a low-to-moderate sorption capacity to soil. Although results may vary with soil type and organic matter content, methomyl is unlikely to persist in complex soils. Methomyl is more rapidly degraded by microbes, and bacterial species have been identified that are capable of using methomyl as a carbon and/or nitrogen source. The main degradation products of methomyl from both abiotic and biotic processes are methomyl oxime, acetonitrile, and CO₂. Methomyl is moderately to highly toxic to fishes and very highly toxic to aquatic invertebrates. Methomyl is highly toxic orally to birds and mammals. Methomyl is classed as being highly toxic to humans via oral exposures, moderately toxic via inhalation, and slightly toxic via dermal exposure. At relatively high doses, it can be fatal to humans. Although methomyl has been widely used to treat field crops and has high water solubility, it has only infrequently been detected as a contaminant of water bodies in the USA. It is classified as a restricted-use insecticide because of its toxicity to multiple nontarget species. To prevent nontarget species toxicity or the possibility of contamination, as with all pesticides, great care should be taken when applying methomyl-containing products for agricultural, residential, or other uses.

Measurement of the pesticide methomyl by modified quartz crystal nanobalance with molecularly imprinted polymer

A simple and cost-effective analysis method based on quartz crystal nanobalance (QCN) coated with a molecularly imprinted polymer (MIP) for measurement of methomyl was investigated. In the first part of this study, a sensitive, selective and reliable quartz crystal nanobalance (QCN) sensor was designed for the selective determination of methomyl in aqueous solutions. In the second part, in order to demonstrate the applicability and performance of the fabricated sensor in the real world situation, it was successfully applied for the determination of methomyl residual in photo catalytic degradation by ZnO powders in aqueous solutions. The fabricated sensor presents a high selectivity and sensitivity (4.56 Hz per mg L(-1)) for methomyl and it can be used for determination of methomyl concentration ranged between 1 to 45 mg L(-1). Furthermore, good reproducibility, R.S.D. = 2.14% (n = 5) was observed. To investigate the performance of the sensor, the change in the insecticide concentration during the photocatalytic degradation of methomyl by ZnO was investigated by QCN and UV/Vis spectroscopy. Results obtained from QCN sensor and UV/Vis spectroscopy measurement are in good mutual agreement. So the fabricated sensor may provide an efficient, low cost, easy-to-use method for the in-field evaluation of specific targeted analytes in aqueous solutions which in turn may lead to improved food and water safety.

Clinical Toxicology of Insecticides

Some insects compete for our food, some damage construction materials and some are important disease vectors in humans and animals. Hence, it is not surprising that chemicals (insecticides) have been developed that kill insects and other arthropods. More recently introduced insecticides, such as the neonicotinoids, have been produced with the intent that humans and animals will not be harmed by their appropriate use. This chapter reviews the clinical features and management of exposure to organophosphorus (OP) and carbamate insecticides, neonicotinoids, phosphides and pyrethroids. In the developing world where the ambient temperature is often high and personal protection equipment often not worn, poisoning particularly from OP and carbamate insecticides is common in an occupational setting, though more severe cases are due to deliberate ingestion of these pesticides. Both of these insecticides produce the cholinergic syndrome. The neonicotinoids, a major new class of insecticide, were introduced on the basis that they were highly specific for subtypes of nicotinic receptors that occur only in insect tissues. However, deliberate ingestion of substantial amounts of a neonicotinoid has resulted in features similar to those found in nicotine (and OP and carbamate) poisoning, though the solvent in some formulations may have contributed to their toxicity. Phosphides interact with moisture in air (or with water or acid) to liberate phosphine, which is the active pesticide. Inhalation of phosphine, however, is a much less frequent cause of human poisoning than ingestion of a metal phosphide, though the toxicity by the oral route is also due to phosphine liberated by contact of the phosphide with gut fluids. It is then absorbed through the alimentary mucosa and distributed to tissues where it depresses mitochondrial respiration by inhibiting cytochrome c oxidase and other enzymes. Dermal exposure to pyrethroids may result in paraesthesiae, but systemic toxicity usually only occurs after ingestion, when irritation of the gastrointestinal tract and CNS toxicity, predominantly coma and convulsions, result.

Mortality rate and pattern following carbamate methomyl poisoning. Comparison with organophosphate poisoning of comparable toxicity

CONTEXT

Methomyl is a widely used carbamate insecticide. It is known that mortality rate is generally low in carbamate poisoning, but fatalities from methomyl poisoning have been reported. Nevertheless, there is no reported comparative outcome of methomyl and organophosphate poisoning of comparable toxicity concerning mortality rate and mortality pattern.

OBJECTIVE

This study aims to compare the mortality rate and pattern following methomyl poisoning with those after organophosphate poisoning of comparable toxicity.

MATERIAL AND METHODS

A retrospective study was conducted on patients with cholinesterase inhibitor poisoning admitted to our institution. Among a diverse group of cholinesterase inhibitors, we included patients who presented after ingesting methomyl or World Health Organisation hazard Class I organophosphate compounds. Patients were divided into two groups; the methomyl group and the Class I organophosphate group.

RESULTS

The methomyl group consisted of 17 patients, and the Class I organophosphate group consisted of 42 patients. Seven patients (41.2%) in the methomyl group presented with cardiac arrest, while none presented with cardiac arrest in the Class I organophosphate group (p < 0.001). In the methomyl group, patients who had not experienced cardiac arrest at presentation survived to discharge from hospital. Among the seven patients who presented with cardiac arrest, three died from multiple organ dysfunction syndrome after resuscitation from cardiac arrest. In the Class I organophosphate group, four patients died from pneumonia and complicating acute respiratory distress syndrome. Therefore, the mortality rate was 17.6% in the methomyl group and 9.5% in the Class I organophosphate group (p = 0.399).

CONCLUSION

The mortality rate of methomyl poisoning was comparable to that of World Health Organisation Class I organophosphate poisoning. All died patients in the methomyl group experienced cardiac arrest, and died from multiple organ dysfunction syndrome after resuscitation from cardiac arrest.

Separation methods for amino group-possessing pesticides in biological samples

The separation methods for pesticides include liquid-liquid extraction, solid-phase extraction and solid-phase microextraction, gas chromatography (GC), GC-mass spectrometry (MS), GC-MS-MS, high-performance liquid chromatography (LC), LC-MS and LC-MS-MS. This review deals with each technique commonly used for extraction, chromatographic separation and detection of amino group possessing pesticides, such as diazines, triazines, carbamates, dinitroanilines and chloroacetanilides in biological samples. The methods presented for analysis of the pesticides in complicated biological matrices seem to be easily applicable to surface or groundwater in environmental chemistry.

Biological Monitoring of Pesticide Exposure: a review. Introduction

Pesticides are used worldwide in agriculture, industry, public health and for domestic applications: as a consequence, a great part of the population may be exposed to these compounds. In spite of this extensive use, knowledge on the health risks associated with prolonged exposure is rather poor, and major uncertainties still exist. Epidemiological observations in man have so far produced little conclusive information, mainly because of weaknesses in exposure assessment. Therefore, information on the type and levels of exposure is fundamental in order to better understand and characterize risk to human health. Exposure assessment can be carried out via measurement of environmental concentrations, as well as via determination of the chemical or its metabolites in body tissues (biological monitoring). Besides indices of internal dose, biological monitoring also includes measurements of early effects attributable to interaction between the chemical agent and the human body. Biological monitoring has the advantage, over environmental monitoring, of determining the dose actually absorbed via any possible route: differences in absorption can be taken into account. whether they are due to biological variability or to use of protective equipment. When, in some cases, a combination of occupational and non-occupational exposure occurs, this also can be taken into consideration by biological monitoring. Few reference documents have been published on biological monitoring of pesticides. For this reason, the Office of Occupational Health of the World Health Organization gave ICPS a mandate to prepare a monograph specifically addressed to reviewing methods for biological monitoring of pesticide exposure. This review is based on more than 300 studies published over the period 1980-1999. For the most representative chemical classes, the available biological exposure indices are reported. Both indices of internal dose and. when available, of early effects are discussed. The reported tests were used to monitor exposure of pesticide applicators in agriculture and public health, manufacturing and formulating workers. subjects poisoned after accidental exposure or attempted suicide, volunteers involved in pharmacokinetic studies, as well as sub-groups of the general population exposed to environmentally persistent pesticides. Single chapters deal with organophosphorus insecticides, carbamate pesticides, dithiocarbamates, phenoxyacids, quaternary ammonium compounds. coumarin rodenticides, synthetic pyrethroids, organochlorine pesticides, chlorotriazines, and pentachlorophenol.

Sensitive determination of methomyl in blood using gas chromatography-mass spectrometry as its oxime tert.-butyldimethylsilyl derivative

A sensitive, selective and reliable method was developed to determine methomyl ¿methyl-N-[(methylcarbamoyl)oxy]-thioacetimidate¿, a carbamate insecticide in human blood, using gas chromatography-mass spectrometry. Dimethylglyoxime served as an internal standard (I.S.). Methomyl in the blood was converted to its oxime form by sodium hydroxide. The solution made acidic with hydrochloric acid was poured into a column packed with Extrelut. Methomyloxime and I.S. were eluted from the column with a mixture of dichloromethane-ethyl acetate-chloroform (65:25:10), transformed to tert.-butyldimethylsilyl derivatives, and analyzed by gas chromatography-mass spectrometry in the electron impact mode. The calibration curves were linear in the concentration range from 1 ng/g to 100 ng/g and 100 ng/g to at least 5000 ng/g. The lower limit of detection was 0.5 ng/g. The absolute recoveries were 72-93% and within-day coefficients of variation were 3.1-5.6% at blood concentrations of 10 and 1000 ng/g. Two practical forensic applications are described.

Acute poisoning with carbamate pesticides: the Cretan experience

In Crete, in southern Greece, a number of fatal carbamate poisonings were investigated over a period of 2 years, from 1991 to 1993. Five cases are reported, involving the fatal ingestion of methomyl (Lannate), a cholinesterase-inhibiting carbamate insecticide. Analysis of samples of blood plasma and serum showed more than 90% inhibition of cholinesterase. The blood methomyl concentrations had a mean value of 26.7 mg/l, and a range of 5.6-57.0 mg/l. These values are much higher than those previously reporter in similar cases (0.57-1.4 mg/l). Methomyl concentrations in organs and tissues were found to be significantly lower than those in blood and vitreous humour.

Determination of disulfoton and its metabolites in the body fluids of a Di-Syston intoxication case

Disulfoton and its metabolites, two sulfoxides and two sulfones, in the body fluids of a patient who had ingested Di-Syston were analyzed by FPD-GC and GC/MS. After the chemicals in the extract (Fraction 1) obtained by Extrelut column extraction were analyzed, disulfoton and sulfoxides in Fraction 1 were oxidized into sulfones. The sulfones in the extract (Fraction 2) obtained by Extrelut column extraction were analyzed and the estimated concentrations of metabolite were calculated. The concentrations of disulfoton and the sum of the metabolites in the blood collected on admission were 0.093 nmol/g (25.4 ng/g) and 4.92 nmol/g (corresponding to 1.35 micrograms/g of disulfoton), respectively. These concentrations appear to indicate a severe level of disulfoton intoxication.