Arsenic Toxicity: Molecular Targets and Therapeutic Agents.

: High arsenic (As) levels in food and drinking water, or under some occupational conditions, can precipitate chronic toxicity and in some cases cancer. Millions of people are exposed to unacceptable amounts of As through drinking water and food. Highly exposed individuals may develop acute, subacute, or chronic signs of poisoning, characterized by skin lesions, cardiovascular symptoms, and in some cases, multi-organ failure. Inorganic arsenite(III) and organic arsenicals with the general formula R-As2+ are bound tightly to thiol groups, particularly to vicinal dithiols such as dihydrolipoic acid (DHLA), which together with some seleno-enzymes constitute vulnerable targets for the toxic action of As. In addition, R-As2+-compounds have even higher affinity to selenol groups, e.g., in thioredoxin reductase that also possesses a thiol group vicinal to the selenol. Inhibition of this and other ROS scavenging seleno-enzymes explain the oxidative stress associated with arsenic poisoning. The development of chelating agents, such as the dithiols BAL (dimercaptopropanol), DMPS (dimercapto-propanesulfonate) and DMSA (dimercaptosuccinic acid), took advantage of the fact that As had high affinity towards vicinal dithiols. Primary prevention by reducing exposure of the millions of people exposed to unacceptable As levels should be the prioritized strategy. However, in acute and subacute and even some cases with chronic As poisonings chelation treatment with therapeutic dithiols, in particular DMPS appears promising as regards alleviation of symptoms. In acute cases, initial treatment with BAL combined with DMPS should be considered.

Interventions for paracetamol (acetaminophen) overdose.

BACKGROUND: Paracetamol (acetaminophen) is the most widely used non-prescription analgesic in the world. Paracetamol is commonly taken in overdose either deliberately or unintentionally. In high-income countries, paracetamol toxicity is a common cause of acute liver injury. There are various interventions to treat paracetamol poisoning, depending on the clinical status of the person. These interventions include inhibiting the absorption of paracetamol from the gastrointestinal tract (decontamination), removal of paracetamol from the vascular system, and antidotes to prevent the formation of, or to detoxify, metabolites. OBJECTIVES: To assess the benefits and harms of interventions for paracetamol overdosage irrespective of the cause of the overdose. SEARCH METHODS: We searched The Cochrane Hepato-Biliary Group Controlled Trials Register (January 2017), CENTRAL (2016, Issue 11), MEDLINE (1946 to January 2017), Embase (1974 to January 2017), and Science Citation Index Expanded (1900 to January 2017). We also searched the World Health Organization International Clinical Trials Registry Platform and ClinicalTrials.gov database (US National Institute of Health) for any ongoing or completed trials (January 2017). We examined the reference lists of relevant papers identified by the search and other published reviews. SELECTION CRITERIA: Randomised clinical trials assessing benefits and harms of interventions in people who have ingested a paracetamol overdose. The interventions could have been gastric lavage, ipecacuanha, or activated charcoal, or various extracorporeal treatments, or antidotes. The interventions could have been compared with placebo, no intervention, or to each other in differing regimens. DATA COLLECTION AND ANALYSIS: Two review authors independently extracted data from the included trials. We used fixed-effect and random-effects Peto odds ratios (OR) with 95% confidence intervals (CI) for analysis of the review outcomes. We used the Cochrane 'Risk of bias' tool to assess the risks of bias (i.e. systematic errors leading to overestimation of benefits and underestimation of harms). We used Trial Sequential Analysis to control risks of random errors (i.e. play of chance) and GRADE to assess the quality of the evidence and constructed 'Summary of findings' tables using GRADE software. MAIN RESULTS: We identified 11 randomised clinical trials (of which one acetylcysteine trial was abandoned due to low numbers recruited), assessing several different interventions in 700 participants. The variety of interventions studied included decontamination, extracorporeal measures, and antidotes to detoxify paracetamol's toxic metabolite; which included methionine, cysteamine, dimercaprol, or acetylcysteine. There were no randomised clinical trials of agents that inhibit cytochrome P-450 to decrease the activation of the toxic metabolite N-acetyl-p-benzoquinone imine.Of the 11 trials, only two had two common outcomes, and hence, we could only meta-analyse two comparisons. Each of the remaining comparisons included outcome data from one trial only and hence their results are presented as described in the trials. All trial analyses lack power to access efficacy. Furthermore, all the trials were at high risk of bias. Accordingly, the quality of evidence was low or very low for all comparisons. Interventions that prevent absorption, such as gastric lavage, ipecacuanha, or activated charcoal were compared with placebo or no intervention and with each other in one four-armed randomised clinical trial involving 60 participants with an uncertain randomisation procedure and hence very low quality. The trial presented results on lowering plasma paracetamol levels. Activated charcoal seemed to reduce the absorption of paracetamol, but the clinical benefits were unclear. Activated charcoal seemed to have the best risk:benefit ratio among gastric lavage, ipecacuanha, or supportive treatment if given within four hours of ingestion. There seemed to be no difference between gastric lavage and ipecacuanha, but gastric lavage and ipecacuanha seemed more effective than no treatment (very low quality of evidence). Extracorporeal interventions included charcoal haemoperfusion compared with conventional treatment (supportive care including gastric lavage, intravenous fluids, and fresh frozen plasma) in one trial with 16 participants. The mean cumulative amount of paracetamol removed was 1.4 g. One participant from the haemoperfusion group who had ingested 135 g of paracetamol, died. There were no deaths in the conventional treatment group. Accordingly, we found no benefit of charcoal haemoperfusion (very low quality of evidence). Acetylcysteine appeared superior to placebo and had fewer adverse effects when compared with dimercaprol or cysteamine. Acetylcysteine superiority to methionine was unproven. One small trial (low quality evidence) found that acetylcysteine may reduce mortality in people with fulminant hepatic failure (Peto OR 0.29, 95% CI 0.09 to 0.94). The most recent randomised clinical trials studied different acetylcysteine regimens, with the primary outcome being adverse events. It was unclear which acetylcysteine treatment protocol offered the best efficacy, as most trials were underpowered to look at this outcome. One trial showed that a modified 12-hour acetylcysteine regimen with a two-hour acetylcysteine 100 mg/kg bodyweight loading dose was associated with significantly fewer adverse reactions compared with the traditional three-bag 20.25-hour regimen (low quality of evidence). All Trial Sequential Analyses showed lack of sufficient power. Children were not included in the majority of trials. Hence, the evidence pertains only to adults. AUTHORS' CONCLUSIONS: These results highlight the paucity of randomised clinical trials comparing different interventions for paracetamol overdose and their routes of administration and the low or very low level quality of the evidence that is available. Evidence from a single trial found activated charcoal seemed the best choice to reduce absorption of paracetamol. Acetylcysteine should be given to people at risk of toxicity including people presenting with liver failure. Further randomised clinical trials with low risk of bias and adequate number of participants are required to determine which regimen results in the fewest adverse effects with the best efficacy. Current management of paracetamol poisoning worldwide involves the administration of intravenous or oral acetylcysteine which is based mainly on observational studies. Results from these observational studies indicate that treatment with acetylcysteine seems to result in a decrease in morbidity and mortality, However, further evidence from randomised clinical trials comparing different treatments are needed.

Severe Systemic Lead Toxicity Resulting From Extra-Articular Retained Shrapnel Presenting as Jaundice and Hepatitis: A Case Report and Review of the Literature.

INTRODUCTION: Despite greater than 60,000 nonfatal firearm injuries per year in the United States, retained shrapnel is a relatively rare cause of systemic lead toxicity with less than 100 cases reported in the medical literature since 1867. While intra-articular retained shrapnel as a cause of lead toxicity is well-described, extra-articular fragments are less well known to cause symptomatic disease. CASE REPORT: A 31-year-old man initially presented with abdominal pain, constipation, jaundice, and elevated liver transaminases approximately 3 weeks after suffering a left lower extremity injury during athletic activity. The patient was found to have steatohepatitis after extensive inpatient and outpatient gastroenterological workup to include upper and lower endoscopy, liver ultrasound, and biopsy of the liver to confirm the diagnosis. Imaging was incidentally notable for retained gunshot in the left flank and large shell fragment containing seroma in the left thigh. The patient was initially discharged with improved pain, but later presented to a primary care clinic with weight loss and continued pain. This was followed by a subsequent progression to diffuse weakness, ultimately resulting in an inability to ambulate. The patient was readmitted to a tertiary care medical center, 3 months after the initial presentation. Physical exam was then notable for 70-lb weight loss from initial admission and diffuse peripheral weakness with global muscle atrophy. Following a broad differential workup, he was found to have a blood lead level of 129 µg/dL, and hemoglobin of 7.7 g/dL with basophilic stippling on peripheral smear. The patient was transferred to the intensive care unit for chelation therapy with dimercaprol and calcium ethylenediaminetetraacetic acid. Lead levels initially decreased, but rose when patient was transitioned to oral therapy with succimer. Surgery was consulted for removal of multiple retained fragments, which were analyzed by the Joint Pathology Center and found to contain lead. The patient's motor function gradually improved on oral chelation and he was discharged to a subacute rehabilitation facility. CONCLUSION: This complex case describes a rare cause for a relatively common clinical presentation, jaundice and hepatitis, and reinforces the importance of longitudinal follow up and reassessment of a patient with an unknown illness and worsening clinical condition. Diagnosis of systemic lead toxicity is challenging because of its protean clinical manifestations, and relative rarity with the advent of strict environmental lead controls and decrease in lead-based paint and industrial products. Furthermore, extra-articular lead remains a rare cause of systemic toxicity, and the surgical standard of care has been to not remove these fragments in gunshot victims. This case adds to a small amount of evidence that lead screening may be of value in selected patients with extra-articular retained shrapnel, especially those with seroma and osteophyte formation in the wound.

Dimercaprol is an acrolein scavenger that mitigates acrolein-mediated PC-12 cells toxicity and reduces acrolein in rat following spinal cord injury.

Acrolein is one of the most toxic byproducts of lipid peroxidation, and it has been shown to be associated with multiple pathological processes in trauma and diseases, including spinal cord injury, multiple sclerosis, and Alzheimer's disease. Therefore, suppressing acrolein using acrolein scavengers has been suggested as a novel strategy of neuroprotection. In an effort to identify effective acrolein scavengers, we have confirmed that dimercaprol, which possesses thiol functional groups, could bind and trap acrolein. We demonstrated the reaction between acrolein and dimercaprol in an abiotic condition by nuclear magnetic resonance spectroscopy. Specifically, dimercaprol is able to bind to both the carbon double bond and aldehyde group of acrolein. Its acrolein scavenging capability was further demonstrated by in vitro results that showed that dimercaprol could significantly protect PC-12 cells from acrolein-mediated cell death in a dose-dependent manner. Furthermore, dimercaprol, when applied systemically through intraperitoneal injection, could significantly reduce acrolein contents in spinal cord tissue following a spinal cord contusion injury in rats, a condition known to have elevated acrolein concentration. Taken together, dimercaprol may be an effective acrolein scavenger and a viable candidate for acrolein detoxification.

Cardiac conduction block at multiple levels caused by arsenic trioxide therapy.

We present a rare case of a woman aged 62 years with refractory acute promyelocytic leukemia treated with arsenic trioxide leading to progressive, multilevel cardiac conduction block. After chelation treatment with dimercaprol, there was normalization of conduction.

2,3-Dimercaptopropanol, a thiol chelator, alleviates gastroduodenal ulcers in rats.

Earlier studies have implicated reactive oxygen species and transitional metals in the pathogenesis of gastric lesions. In this study, we have evaluated the effect of 2,3-dimercaptopropanol (DMP), a thiol compound and metal chelator, on chemically induced gastroduodenal ulcers in rats. Acid secretion studies were undertaken using pylorus-ligated rats pretreated with DMP (3-100 mg/kg, i.p.). The effect of orally administered DMP on cysteamine-induced duodenal ulcers and ethanol-induced gastric ulcers was also tested. The level of nonprotein sulfhydryls (NP-SH) and gastric wall mucus was measured in the glandular stomach of rats treated with ethanol. None of the dose of DMP affected the volume or acidity of gastric secretion. Low doses of DMP (3 and 10 mg/kg) significantly reduced cysteamine-induced duodenal ulcers, whereas the high doses (30 and 100 mg/kg) were ineffective in this model. All the doses of DMP significantly and dose dependently attenuated ethanol-induced gastric lesions. The adverse effects of ethanol on gastric wall mucus and NP-SH were significantly and dose dependently reversed by DMP. In conclusion, the protective effects of DMP appear to be independent of gastric acid secretion and may be associated with counteracting the oxidative stress by replenishing glutathione and reducing the pool of transition metals.

Doença de Wilson (degeneração hepatolenticular): revisão bibliográfica e relato de caso / Wilson’s disease (hepatolenticular degeneration): revision and case report

Este estudo faz, inicialmente, revisão dos aspectos mais atuais referentes a conceito, quadro clínico, diagnóstico e tratamento do distúrbio metabólico do cobre, definido como doença de Wilson. E relata o caso clínico de um jovem acometido de uma sequência de sintomas superpostos de origem gastrintestinal, neurológico e psiquiátrico. Pela multiplicidade e gravidade dos sintomas, teve o diagnóstico final de transtorno psicótico agudo polimórfico, com intensa inibição psicomotora. A partir de uma análise integrada dos exames já solicitados, suspeitou-se de um distúrbio metabólico de origem hereditária ou adquirida que justificasse simultaneamente os sintomas. O distúrbio da excreção do cobre, doença de Wilson, veio justificar toda a sintomatologia referida e foi confirmado a partir da dosagem sanguínea baixa de ceruloplasmina e da presença dos anéis de Kaiser-Fleischer na córnea do paciente.

It will be initially revised by the authors the most actual aspects of the concept, clinical situation, diagnosis and treatment concerning to a metabolic disturbance of the copper, Wilson?s disease. Afterwards it will be described the clinical case of a young man attacked of a sequence of superposed symptoms of gastrintestinal, neurological and psychiatric origin. For the multiplicity and gravity of the symptoms acute polimórfico with intense psicomotora inhibition had the final diagnosis of "psychotic Upheaval". Starting from an integrated analysis of the exams, it was suspected about a metabolic disturbance of hereditary or acquired origin that justify all the symptoms simultaneously. The disturbance of the excretion of copper, Wilson's disease, came to justify all the referred symptomatology and it was confirmed by the decrease sanguine dosage of ceruloplasmin, the presence of rings of Kayser-Fleischer in the córnea of the patient and of neurological lesion at the magnetic nuclear ressonance. The diagnosis of Wilson's disease in patients with simultaneous digestive (hepática cirrhosis), neurological and inexplicable psychiatric disturbances will always have to be faneed because the precocious treatment will mainly prevent serious and permanent organic damages for the liver and brain. The specific treatment was initiated and the maintenance of exactly has provoked significant improvements and a gradual new outbreak of the symptoms reintegrating the patient the family and the society.

Arsenic induced oxidative stress and the role of antioxidant supplementation during chelation: a review.

Arsenic is a naturally occurring metalloid, ubiquitously present in the environment in both organic and inorganic forms. Arsenic contamination of groundwater in the West Bengal basin in India is unfolding as one of the worst natural geoenvironmental disaster to date. Chronic exposure of humans to high concentration of arsenic in drinking water is associated with skin lesions, peripheral vascular disease, hypertension, Blackfoot disease and high risk of cancer The underlying mechanism of toxicity includes the interaction with the sulphydryl groups and the generation of reactive oxygen species leading to oxidative stress. Chelation therapy with chelating agents like British Anti Lewisite (BAL), sodium 2,3-dimercaptopropane 1-sulfonate (DMPS), meso 2,3 dimercaptosuccinic acid (DMSA) etc., is considered to be the best known treatment against arsenic poisoning. The treatment with these chelating agents however is compromised with certain serious drawbacks/side effects. The studies show that supplementation of antioxidants along with a chelating agent prove to be a better treatment regimen. This review attempts to provide the readers with a comprehensive account of recent developments in the research on arsenic poisoning particularly the role of oxidative stress/free radicals in the toxic manifestation, an update about the recent strategies for the treatment with chelating agents and a possible beneficial role of antioxidants supplementation to achieve the optimum effects.

Toxicity induced by Hg2+ on choline acetyltransferase activity from E. electricus (L.) electrocytes: the protective effect of 2,3 dimercapto-propanol (BAL).

BACKGROUND: The effect of mercury (Hg(2+)) on the activity of choline acetyltransferase (ChAT) from electrocytes of Electrophorus electricus (L.) was studied due to the importance of this enzyme and acetylcholine in many neurochemical functions such as arousal, learning, and memory. MATERIAL/METHODS: Mercury, which has affinity to thiol groups, acted as a potent inhibitor of ChAT, which was obtained by differential centrifugation and ammonium sulfate precipitation, at 80%, from the main electric organ homogenate. RESULTS: Mercury inhibition presents different kinetic behaviors for both enzyme substrates: noncompetitive to choline and of mixed type to AcCoA, with inhibition constants on the order of 0.5 to 1.0 microM. The enzyme activity was recovered using 2,3 dimercapto-propanol (BAL), a well-known chelate for sulphydryl groups and metals, which acted as a protecting agent and was able to revert the Hg(2+) inhibition at a concentration of 10 (-6) M. After treatment with this metal and in the presence of 2,3 dimercapto-propanol, 70% of the enzyme activity was recovered for AcCoA and 80% for choline. CONCLUSIONS: The observed inhibition is likely due to direct protein interaction, because the addition of BAL reversed the effects of HgCl(2) on ChAT activity. The results cast new light on the mechanisms of mercurial neurotoxicity.

Consequences of acute and chronic exposure to arsenic in children.

Arsenic is a toxic chemical and may cause adverse health effects in children and adults. It is known to affect the nervous, gastrointestinal, and hematological systems and cause skin and internal cancers in people exposed to levels greater than 300 ppb in their drinking water. For most people, the major exposure to arsenic comes from food (8 to 14 microg inorganic arsenic per day), but when the arsenic level in water is elevated, drinking water becomes the predominant source of exposure. Because it is very difficult to limit arsenic exposure from food, it would be wise to limit arsenic exposure from those more controllable sources. Pediatricians should ascertain the levels of arsenic in drinking water of patients with high arsenic levels, using the supplier or, in the case of private wells, a professional water-testing laboratory assay. The Safe Drinking Water Act does not cover private wells or those water systems with less than 15 hook-ups or those that serve less than 25 people. Pediatricians should instruct parents to use prepared baby formulas or prepare them using water with the arsenic removed and to curtail playing time for younger children in places that have sand containing large amounts of arsenic. Such procedures will limit arsenic exposure to a minimum.

FDA-preapproved drugs targeted to the translational regulation and processing of the amyloid precursor protein.

The 5' untranslated region (5'UTR) of the transcript encoding the Alzheimer's amyloid precursor protein (APP) is a key regulatory sequence that determines the amount of intracellular APP holoprotein present in brain derived cells. Using neuroblastoma cells (SY5Y) we developed a transfection based screen of a library of FDA drugs to identify compounds that limited APP luciferase reporter expression translated from the APP 5'UTR. Paroxetine (Paxil trade mark ), dimercaptopropanol, phenserine, desferrioxamine, tetrathiolmobdylate, and azithromycin were six leads that were subsequently found to also suppress APP holoprotein levels or to alter APP cleavage (azithromycin). Since APP holoprotein levels are proportionate to Abeta peptide output in many systems we tested the efficacy of paroxetine and dimercaptopropanol to limit Abeta secretion as measured by ELISA assays. Paroxetine and dimercaptopropanol limited Abeta peptide secretion from lens epithelial cells (B3 cells). Interestingly, paroxetine changed the steady-state levels of transferrin receptor mRNAs. These data suggested that this serotonin reuptake inhibitor (SSRI) provided extra pharmacological action to chelate interacellular iron or change the intracellular iron distribution. An altered iron distribution would be predicted to indirectly limit APP holoprotein expression and Abeta peptide secretion.

Suicidal mercury injection into the upper limb: a case study.

We report a rare case of self-injection of mercury into the subcutaneous tissue of the upper limb. A multi-disciplinary management approach was adopted including cooperation between toxicologists, orthopaedic surgeons, radiologists and environment safety personnel. Surgical removal of mercury under radiological screening and systemic intoxication treated by chelating agents, namely dimercaprol and succimer. Serial serum and urine mercury levels showed an initial rise despite surgical removal and returned to normal after a prolonged period of time. Safety precautions were taken during surgery to avoid inadvertent intoxication of staff. Contamination of the operation theatre was monitored by the amount of mercury vapour released into the air. All personnels involved in the management of the patient did not show any evidence of mercury intoxication.

[Shotgun injury of head and neck: case report].

A 48-year-old male was hit by a shotgun blast from behind while he was hunting. He was only 7 meters away when one of his colleagues pulled the trigger accidentally. About 180 lead pellets penetrated his head and neck. When he was brought to our hospital, he was alert and complained of occipital and nape pain, but had no apparent neurological deficits. We administered 200 mg of dimercaprol immediately and removed 77 pellets by midline suboccipital incision on the next day. Afterwords, we performed four minor operations using a fluoroscope, and removed another 70 pellets by day 29. In addition, we administered a 100 mg x 3 dose of dimercaprol every other week. He was discharged 41 days after the accident without any acute signs of lead poisoning. Though serum lead level did not rise to critical level, EDTA was continued after his discharge to prevent delayed lead poisoning from the retained pellets. Since we seldom encounter this type of patient in Japan, delayed lead poisoning by shotgun injury was discussed with reference to the literature.

Role of ATP-sensitive potassium channels in prostaglandin-mediated gastroprotection in the rat.

This study compares the involvement of ATP-sensitive potassium (K(ATP)) channels and prostaglandins in various forms of gastroprotection in the rat. Instillation of 1 ml of 70% ethanol induced severe gastric mucosal damage (lesion index 39 +/- 0.8), which was substantially but not maximally reduced by oral pretreatment with 16,16-dimethyl-prostaglandin (PG) E(2) (75 ng/kg), 20% ethanol (1 ml), sodium salicylate (15 mg/kg), the metal salt lithium chloride (7 mg/kg), the sulfhydryl-blocking agent diethylmaleate (5 mg/kg), and the thiol dimercaprol (10 mg/kg). Administration of indomethacin (20 mg/kg) increased gastric mucosal damage induced by 70% ethanol (lesion index 45 +/- 0.8) and significantly reduced the protective effect of 20% ethanol, sodium salicylate, lithium chloride, diethylmaleate, and dimercaprol. The blocker of K(ATP) channels glibenclamide (5-10 mg/kg) significantly antagonized the protective effect of 16,16-dimethyl-PGE(2), 20% ethanol, sodium salicylate, lithium chloride, diethylmaleate, and dimercaprol. The inhibition of protection induced by glibenclamide was reversed by pretreatment with the K(ATP) channel activator cromakalim (0.3-0.5 mg/kg). In conclusion, our results indicate a role of K(ATP) channels in the gastroprotective effect of 16,16-dimethyl-PGE(2) and of the other agents tested. Since the protection afforded by these agents is additionally indomethacin-sensitive, it is suggested that under these conditions endogenous prostaglandins act as activators of K(ATP) channels, and this mechanism, at least in part, mediates gastroprotection.

Mobilization of heavy metals by newer, therapeutically useful chelating agents.

Four chelating agents that have been used most commonly for the treatment of humans intoxicated with lead, mercury, arsenic or other heavy metals and metalloids are reviewed as to their advantages, disadvantages, metabolism and specificity. Of these, CaNa2EDTA and dimercaprol (British anti-lewisite, BAL) are becoming outmoded and can be expected to be replaced by meso-2,3-dimercaptosuccinic acid (DMSA, succimer) for treatment of lead intoxication and by the sodium salt of 2,3-dimercapto-1-propanesulfonic acid (DMPS, Dimaval) for treating lead, mercury or arsenic intoxication. Meso-2,3-DMSA and DMPS are biotransformed differently in humans. More than 90% of the DMSA excreted in the urine is found in the form of a mixed disulfide in which each of the sulfur atoms of DMSA is in disulfide linkage with an L-cysteine molecule. After DMPS administration, however, acyclic and cyclic disulfides of DMPS are found in the urine. The Dimaval-mercury challenge test holds great promise as a diagnostic test for mercury exposure, especially for low level mercurialism. Urinary mercury after Dimaval challenge may be a better biomarker of low level mercurialism than unchallenged urinary mercury excretion.

Intoxicaçäo crônica por chumbo / Chronic lead poisoning

Os autores relatam o caso de paciente de 30 anos, do sexo masculino, proveniente de Apucarana-PR, que desenvolveu alteraçöes gastrintestinais neurológicas graves devido à exposiçäo ao chumbo durante 10 anos. Trabalhava em fábrica de baterias automotivas, mantendo durante este período contato cutâneo e inalatório com o produto.

Arsenic: the forgotten poison?

Chronic arsenic poisoning is an uncommon cause of peripheral neuropathy in Jamaica. A patient with this disorder is described. The insidious nature of chronic arsenic poisoning, with its disabling complications, is emphasised.