Arsine toxicity aboard the Asiafreighter

Toxicity of so-called edible hijiki seaweed (Sargassum fusiforme) containing inorganic arsenic

The UK Food Standards Agency and its counterparts in other countries have warned consumers not to eat hijiki (Sargassum fusiforme; synonym Hizikia fusiformis), a Sargasso seaweed, because it contains large amounts of inorganic arsenic. We investigated dietary exposure of hijiki in weaning male F344/N rats fed an AIN-93G diet supplemented with 3% (w/w) hijiki powder for 7 weeks, compared with those fed only an AIN-93G diet. Body weight, body temperature, blood and tissue arsenic concentrations, plasma biochemistry and hematological parameters were measured. We found that feeding rats a 3% hijiki diet led to a marked accumulation of arsenic in blood and tissues, and evoked a high body temperature and abnormal blood biochemistry including elevated plasma alkaline phosphatase activity and inorganic phosphorus, consistent with arsenic poisoning. These findings should prompt further investigations to identify the health hazards related to consumption of hijiki and related Sargassum species in humans.

Chronic kidney disease associated with environmental toxins and exposures

People are exposed to various potentially toxic agents and conditions in their natural and occupational environments. These agents may be physical or chemical, may enter the human body through oral, inhalational, or transdermal routes, and may exert effects on all organ systems. Several well-known as well as lesser known associations exist between chronic kidney disease (CKD) and both environmental agents and conditions, such as heavy metals, industrial chemicals, elevated ambient temperatures, and infections. The effects of these agents may be modulated by genetic susceptibility and other comorbid conditions and may lead to the development of acute and CKD. In this article, we present environmental factors that are associated with CKD.

Arsenic neurotoxicity--a review

Arsenic (As) is one of the oldest poisons known to men. Its applications throughout history are wide and varied: murder, make-up, paint and even as a pesticide. Chronic As toxicity is a global environmental health problem, affecting millions of people in the USA and Germany to Bangladesh and Taiwan. Worldwide, As is released into the environment by smelting of various metals, combustion of fossil fuels, as herbicides and fungicides in agricultural products. The drinking water in many countries, which is tapped from natural geological resources, is also contaminated as a result of the high level of As in groundwater. The environmental fate of As is contamination of surface and groundwater with a contaminant level higher than 10 particle per billion (ppb) as set by World Health Organization (WHO). Arsenic exists in both organic and inorganic species and either form can also exist in a trivalent or pentavalent oxidation state. Long-term health effects of exposure to these As metabolites are severe and highly variable: skin and lung cancer, neurological effects, hypertension and cardiovascular diseases. Neurological effects of As may develop within a few hours after ingestion, but usually are seen in 2-8 weeks after exposure. It is usually a symmetrical sensorimotor neuropathy, often resembling the Guillain-Barré syndrome. The predominant clinical features of neuropathy are paresthesias, numbness and pain, particularly in the soles of the feet. Electrophysiological studies performed on patients with As neuropathy have revealed a reduced nerve conduction velocity, typical of those seen in axonal degeneration. Most of the adverse effects of As, are caused by inactivated enzymes in the cellular energy pathway, whereby As reacts with the thiol groups of proteins and enzymes and inhibits their catalytic activity. Furthermore, As-induced neurotoxicity, like many other neurodegenerative diseases, causes changes in cytoskeletal protein composition and hyperphosphorylation. These changes may lead to disorganization of the cytoskeletal framework, which is a potential mechanism of As-induced neurotoxicity.

Severe acute arsine poisoning treated by plasma exchange

INTRODUCTION

Exposure to arsine gas can cause fatal hemolysis and multiorgan damage. Whole blood exchange transfusion and hemodialysis have been recommended to treat severe acute arsine poisoning, but are associated with significant complications and sub-optimal outcomes. Plasma exchange is another method of blood purification technique but there are no data on its use in acute arsine poisoning. This retrospective study evaluated the clinical and effects and arsenic clearance from the use of plasma exchange treatment of patients with acute arsine poisoning.

METHODS

Data from patients with severe acute arsine poisoning, treated with plasma exchange from December 2000 to December 2005 were collected and analyzed. Measured laboratory factors, performed before and after plasma exchange treatment included routine biochemistry and hematology tests as well as arsenic concentrations in blood, urine, and discarded plasma.

RESULTS

During the study period, 12 patients with severe acute arsine poisoning were treated with plasma exchange. Plasma exchange was performed one or two times on each patient, during which the replacement fluid was fresh frozen plasma (total volume ranged from 1,400 to 4,000 mL). The range of concentrations of arsenic in discarded plasma was 27.7 to 88.7 mg/L and the range of total arsenic removed by plasma exchange was 55.4 to 177.4 mg. Plasma exchange appears to rapidly terminate arsine-induced hemolysis and favorably modify damage to the kidneys and other organs. Laboratory factors that showed significant association with treatment response were creatine kinase, lactate dehydrogenase, blood urea nitrogen, total bilirubin, and heart-related enzymes. All patients recovered from the poisoning and were in good condition at a 2 to 3 months follow-up.

CONCLUSIONS

Plasma exchange appears to be an effective treatment intervention for patients with severe acute arsine poisoning. It is suggested that it be used as early as possible.

Oxidant stress and haemolysis of the human erythrocyte

The erythrocyte is a highly specialised cell with a limited metabolic repertoire. As an oxygen shuttle, it must continue to perform this essential task while exposed to a wide range of environments on each vascular circuit, and to a variety of xenobiotics across its lifetime. During this time, it must continuously ward off oxidant stress on the haeme iron, the globin chain and on other essential cellular molecules. Haemolysis, the acceleration of the normal turnover of senescent erythrocytes, follows severe and irreversible oxidant injury. A detailed understanding of the molecular mechanisms underlying oxidant injury and its reversal, and of the clinical and laboratory features of haemolysis is important to the medical toxicologist. This review will also briefly review glucose-6-phosphate deficiency, a common but heterogeneous range of enzyme-deficient states, which impairs the ability of the erythrocyte to respond to oxidant injury.

Acute and chronic arsenic toxicity

Arsenic toxicity is a global health problem affecting many millions of people. Contamination is caused by arsenic from natural geological sources leaching into aquifers, contaminating drinking water and may also occur from mining and other industrial processes. Arsenic is present as a contaminant in many traditional remedies. Arsenic trioxide is now used to treat acute promyelocytic leukaemia. Absorption occurs predominantly from ingestion from the small intestine, though minimal absorption occurs from skin contact and inhalation. Arsenic exerts its toxicity by inactivating up to 200 enzymes, especially those involved in cellular energy pathways and DNA synthesis and repair. Acute arsenic poisoning is associated initially with nausea, vomiting, abdominal pain, and severe diarrhoea. Encephalopathy and peripheral neuropathy are reported. Chronic arsenic toxicity results in multisystem disease. Arsenic is a well documented human carcinogen affecting numerous organs. There are no evidence based treatment regimens to treat chronic arsenic poisoning but antioxidants have been advocated, though benefit is not proven. The focus of management is to reduce arsenic ingestion from drinking water and there is increasing emphasis on using alternative supplies of water.

Poisoning at sea: injuries caused by chemicals aboard Danish merchant ships 1988-1996

INTRODUCTION

Injuries involving chemicals occur aboard merchant ships, since such agents are carried commonly on board either as cargo or as needed for running the ship. In case of events involving chemicals, the crew may seek advice from the Medical First Aid Guide for Use in Accidents Involving Dangerous Goods published by the International Maritime Organization. The Guide is currently under revision. To improve knowledge of what is relevant in such a guide, a study was undertaken to identify all intoxications and corrosive incidents occurring aboard Danish merchant ships.

METHODS

A retrospective study of all intoxications and corrosive incidents reported to the Danish Maritime authorities between 1988 and 1996.

RESULTS

A total of 177 injuries were identified, of which 66 were systemic poisonings and 111 were due to corrosive damage to the eyes and skin. Thirteen of 66 systemic poisonings were fatal and almost three out of four corrosive injuries involved the eyes.

CONCLUSIONS

This study and others show that the majority of injuries aboard merchant ships involving dangerous goods are amenable to first aid and symptomatic measures. Specific antidotes seem to have a limited role aboard merchant ships.

Chemical disasters

Chemical disasters are sufficiently common that plans are needed to prevent them, or to mitigate their effects should they occur. However, they are sufficiently rare that any individual is likely to have little or no experience of them. This article reviews chemical disasters which have been reported in the medical literature, and briefly discusses plans for medical involvement in the prevention and tackling of such events.

Toxic gases

An overview of the widespread use of gases and some volatile solvents in modern society is given. The usual circumstances in which undue exposure may occur are described. The most prominent symptoms and general principles of diagnosis and treatment are given and are followed by more specific information on the commoner, more toxic materials. While acute poisonings constitute the greater part of the paper, some indication of chronic disorders arising from repeated or prolonged exposure is also given.

Acute arsenic intoxication presenting as Guillain-Barré-like syndrome

Arsenic-induced polyneuropathy is traditionally classified as an axonal-loss type, electrodiagnostically resulting in low amplitude or absent sensory and motor responses, relatively preserved proximal and distal motor conduction rates, and distal denervation. We report four patients with a subacute onset progressive polyradiculoneuropathy following high-dose arsenic poisoning. In three patients, early electrodiagnostic testing demonstrated findings suggestive of an acquired segmental demyelinating polyradiculoneuropathy. Serial testing confirmed evolution into features of a distal dying-back neuropathy. We hypothesize that arsenic toxicity and the resultant biochemical derangement of the peripheral nerve cell leads to subtle changes in axonal function that produce, initially, segmental demyelination and eventually distal axonal degeneration. Acute arsenic toxicity must be suspected in patients with clinical and electrodiagnostic features supporting Guillain-Barré syndrome.

Clinical and environmental aspects of arsenic toxicity

Arsenic is widely distributed throughout the animal and plant kingdoms and our environment where sources can be natural or anthropogenic. Agricultural uses of arsenic have declined recently, but it still has well-defined roles in industry. Small amounts of arsenic are metabolized in a variety of ways and are largely rapidly methylated and excreted by man and animals. Poisoning can occur and may follow an acute or chronic course. Toxic manifestations in man occur at the cellular level and may appear in many organ systems. Specific effects can often be demonstrated in the skin and in the vascular and nervous systems. Other toxic effects appear to include carcinogenesis, mutagenesis, and teratogenesis.

D-penicillamine therapy of acute arsenic poisoning

Severe poisoning resulting from single ingestions of rodenticides, herbicides, or insecticides containing arsenic have been frequently recognized. We record three cases of solubilized arsenic trioxide poisoning in Navajo Indian children and one case of sodium arsenate ingestion in an infant. One fatality occurred during dimercaprol therapy prior to initiation of therapy with D-penicillamine. Three survivors were treated with 2.3-dimercaprol intramuscularly and with oral D-penicillamine. The use of D-penicillamine in arsenic poisoning has not been generally appreciated. Excretion data from the three children are presented which document the effectiveness of D-penicillamine, administered orally in four daily doses of 25 mg/kg/dose, in the therapy of arsenic intoxication. Excretion data for the trace metals, zinc and copper, during D-penicillamine chelation therapy are also reported.