Arsine toxicity: chemical and mechanistic implications

Is secondary chemical exposure of hospital personnel of clinical importance?

INTRODUCTION

There is increasing concern among hospital personnel about potential secondary exposure when treating chemically contaminated patients.

OBJECTIVE

To assess which circumstances and chemicals require the use of Level C Personal Protective Equipment (chemical splash suit and air-purifying respirator), to prevent secondary contamination of hospital personnel treating a chemically contaminated patient.

METHODS

The US National Library of Medicine PubMed database was searched for the years 1985 to 2020 utilizing combinations of relevant search terms. This yielded 557 papers which were reviewed by title and abstract. After excluding papers on biological or radiological agents, or those not related to hospital personnel, 38 papers on chemicals remained. After a full-text review, 13 papers without an in-depth discussion on the risk for secondary contamination were omitted, leaving 25 papers for review. The references of these papers were searched and this yielded another seven additional citations, bringing the total to 32 papers.

INCIDENCE OF SECONDARY TOXICITY

Secondary toxicity in hospital personnel is rare: a large-scale inventory of 120,000 chemical incidents identified only nine cases, an occurrence of 0.0075%.

SKIN CONTACT AS A SECONDARY EXPOSURE ROUTE

Skin exposure is rare under normal hygienic working conditions, reflected by the very small number of cases reported in the literature: two cases with corrosive effects due to unprotected contact and one case of presumed skin absorption.

INHALATION AS A SECONDARY EXPOSURE ROUTE

Most case reports described secondary toxicity as a result of inhalation. The chemicals involved were irritating solid particles (capsaicin spray/CS), toxic gases formed in the stomach of patients (arsine/hydrazoic acid/phosphine) and vapours from volatile liquids (solvents).

FEATURES OF SECONDARY TOXICITY

Reported symptoms after secondary inhalation were generally mild and reversible (mostly irritation of eyes and respiratory tract, nausea, headache, dizziness/light-headedness) and did not require treatment. In many cases, special circumstances increased exposure: treatment/decontamination of multiple patients, regurgitation of the chemical agent from the stomach, or inadequate room ventilation.

USE OF MORE THAN STANDARD PERSONAL PROTECTIVE EQUIPMENT

Normal hygienic precautions prevent direct skin contact from exposure to common chemical agents. When solid particle contamination is extensive, a mask and eye protection should be applied. Splash proof outer clothing (splash suit) and eye protection is preferred if (partial) wet decontamination is performed on single patients. Adequate ventilation, careful removal of clothing in case of solid particles contamination and adequate disposal of gastric content reduces exposure. Hospital staff can be rotated if symptoms occur, which can be odour-mediated. The use of more elaborate personal protective equipment with an air-purifying respirator (Level C) is only necessary in exceptional cases of contamination with highly toxic volatile chemicals (e.g., sarin). It should also be considered when decontaminating a large number of patients.

CONCLUSIONS

The risk of secondary contamination and subsequent toxicity in hospital personnel decontaminating or treating chemically contaminated patients is small. Normal hygienic precautions (gloves and water-resistant gown) will adequately protect hospital staff when treating the majority of chemically contaminated patients. More extensive protection is only necessary infrequently and there is no reason to delay critical care, even if more elaborate protection is not immediately available.

Arsenic waste management: a critical review of testing and disposal of arsenic-bearing solid wastes generated during arsenic removal from drinking water

Water treatment technologies for arsenic removal from groundwater have been extensively studied due to widespread arsenic contamination of drinking water sources. Central to the successful application of arsenic water treatment systems is the consideration of appropriate disposal methods for arsenic-bearing wastes generated during treatment. However, specific recommendations for arsenic waste disposal are often lacking or mentioned as an area for future research and the proper disposal and stabilization of arsenic-bearing waste remains a barrier to the successful implementation of arsenic removal technologies. This review summarizes current disposal options for arsenic-bearing wastes, including landfilling, stabilization, cow dung mixing, passive aeration, pond disposal, and soil disposal. The findings from studies that simulate these disposal conditions are included and compared to results from shorter, regulatory tests. In many instances, short-term leaching tests do not adequately address the range of conditions encountered in disposal environments. Future research directions are highlighted and include establishing regulatory test conditions that align with actual disposal conditions and evaluating nonlandfill disposal options for developing countries.

Differential modulation of cytochrome P450 1a1 by arsenite in vivo and in vitro in C57BL/6 mice

Heavy metals, typified by arsenite (As(III)), have been implicated in altering the carcinogenicity of aryl hydrocarbon receptor (AhR) ligands, typified by 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), by modulating the induction of the Cyp1a1 enzyme, but the mechanism remains unresolved. In this study, the effects of As(III) on Cyp1a1 expression and activity were investigated in C57BL/6 mouse livers and isolated hepatocytes. For this purpose, C57BL/6 mice were injected intraperitoneally with As(III) (12.5 mg/kg) in the absence and presence of TCDD (15 μg/kg) for 6 and 24 h. Furthermore, isolated hepatocytes from C57BL/6 mice were treated with As(III) (1, 5, and 10 μM) in the absence and presence of TCDD (1 nM) for 3, 6, 12, and 24 h. At the in vivo level, As(III) decreased the TCDD-mediated induction of Cyp1a1 mRNA at 6h while potentiating its mRNA, protein, and catalytic activity levels at 24 h. At the in vitro level, As(III) decreased the TCDD-mediated induction of Cyp1a1 mRNA in a concentration- and time-dependent manner. Moreover, As(III) decreased the TCDD-mediated induction of Cyp1a1 protein and catalytic activity levels at 24 h. Interestingly, As(III) increased the serum hemoglobin (Hb) levels in animals treated for 24 h. Upon treatment of isolated hepatocytes with Hb alone, there was an increase in the nuclear accumulation of AhR and AhR-dependent luciferase activity. Furthermore, Hb potentiated the TCDD-induced AhR-dependent luciferase activity. Importantly, when isolated hepatocytes were treated for 5h with As(III) in the presence of TCDD and the medium was then replaced with new medium containing Hb, there was potentiation of the TCDD-mediated effect. Taken together, these results demonstrate for the first time that there is a differential modulation of the TCDD-mediated induction of Cyp1a1 by As(III) in C57BL/6 mouse livers and isolated hepatocytes. Thus, this study implicates Hb as an in vivo-specific modulator.

Application of hybrid blood purification treatment for severe acute arsine poisoning

OBJECTIVE

Severe acute arsine poisoning (SAAP) complicated by multiple organ dysfunction syndrome is a critical clinical illness. The limited efficacy of conventional drug therapy prompted us to investigate the application of hybrid blood purification treatment (HBPT) to improve the prognosis in critically ill patients. The present manuscript describes a series of cases treated with HBPT.

METHODS

Eleven SAAP subjects were enrolled. The study did not include a control group, because of ethical issues. On the basis of conventional therapy, HBPT (plasma exchange [PE] + continuous venovenous hemofiltration [CVVH]) was used to treat SAAP. PE was performed once a day for 5 days, and CVVH was performed after each session of PE for 7 days or more; HBPT treatment duration amounted to an average of 10 days (range 7-18 days). Arsenic was detected in blood and discarded liquid. Clinical indicators, laboratory parameters, and prognostic indicators were assessed.

RESULTS

HBPT was smoothly implemented without obvious adverse reaction. It can continuously remove arsenic and terminate hemolysis in a time-dependent manner. HBPT also significantly improved the poor clinical manifestations and laboratory indicators of SAAP, leading to a low mortality. Ten patients were discharged because of improved conditions, and only 1 patient died.

CONCLUSIONS

The early application of HBPT can improve the prognosis of SAAP. The advantage of HBPT is that it can integrate the characteristics of different blood purification technologies to maximize treatment efficacy.

Heavy metal poisoning: management of intoxication and antidotes

Of the known elements, nearly 80% are either metals or metalloids. The highly reactive nature of most metals result in their forming complexes with other compounds such oxygen, sulfide and chloride. Although this reactivity is the primary means by which they are toxic, many metals, in trace amounts, are vital to normal physiological processes; examples include iron in oxygen transport, manganese and selenium in antioxidant defense and zinc in metabolism. With these essential metals toxicity occurs when concentrations are either too low or too high. For some metals there are no physiological concentrations that are beneficial; as such these metals only have the potential to cause toxicity. This chapter focuses on four of these: arsenic, mercury, lead and thallium.

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.

Hazardous effects of arsine: a short review

This review details the known health effects of arsine as well as the existing theories on the mechanism by which arsine exerts its toxic effect and conditions of occupational exposure to this gas. Exposure to arsine in occupational settings occurs mostly in the chemical and metallurgical industries when nascent hydrogen reacts with metallic arsenic or arsenic compounds. The available data indicate that in these branches of industry arsine is often a cause of unexpected serious poisoning. The gas affects primarily blood and kidneys. Acute arsine poisoning is known to result in massive damage to red blood cells through the oxidative mechanism, probably by the formation of hydrogen peroxide and adducts with oxyhemoglobin. According to another hypothesis, arsine acts on sodium-potassium pomp mechanism, producing subsequent red blood cell swelling and hemolysis. Rapid hemolysis may lead to oliguric renal failure and death. Symptoms of chronic poisoning are similar to those observed in acute poisoning. The main difference is a longer latency period. Late effects of chronic exposure to low levels of arsine have not yet been precisely identified.

Heavy Metal Poisoning: Clinical Presentations and Pathophysiology

Humans have had a long and tumultuous relationship with heavy metals. Their ubiquitous nature and our reliance on them for manufacturing have resulted at times in exposures sufficient to cause systemic toxicity. Their easy acquisition and potent toxicity have also made them popular choices for criminal poisonings. This article examines the clinical manifestation and pathophysiology of poisoning from lead, mercury, arsenic, and thallium.

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.

The metabolism of inorganic arsenic oxides, gallium arsenide, and arsine: a toxicochemical review

The aim of this review is to compare the metabolism, chemistry, and biological effects to determine if either of the industrial arsenicals (arsine and gallium arsenide) act like the environmental arsenic oxides (arsenite and arsenate). The metabolism of the arsenic oxides has been extensively investigated in the past 4 years and the differences between the arsenic metabolites in the oxidation states +III versus +V and with one or two methyl groups added have shown increased importance. The arsenic oxide metabolism has been compared with arsine (oxidation state -III) and arsenide (oxidation state between 0 to -III). The different metabolites appear to have different strengths of reaction for binding arsenic (III) to thiol groups, their oxidation-reduction reactions and their forming an arsenic-carbon bond. It is unclear if the differences in parameters such as the presence or absence of methyl metabolites, the rates of AsV reduction compared to the rates of AsIII oxidation, or the competition of phosphate and arsenate for cellular uptake are large enough to change biological effects. The arsine rate of decomposition, products of metabolism, target organ of toxic action, and protein binding appeared to support an oxidized arsenic metabolite. This arsine metabolite was very different from anything made by the arsenic oxides. The gallium arsenide had a lower solubility than any other arsenic compound and it had a disproportionate intensity of lung damage to suggest that the GaAs had a site of contact interaction and that oxidation reactions were important in its toxicity. The urinary metabolites after GaAs exposure were the same as excreted by arsenic oxides but the chemical compounds responsible for the toxic effects of GaAs are different from the arsenic oxides. The review concludes that there is insufficient evidence to equate the different arsenic compounds. There are several differences in the toxicity of the arsenic compounds that will require substantial research.

Chemicals and gases

This article covers the major chemicals and gases that are considered to be of the most clinical relevance to the primary care provider. The reader is referred to other comprehensive textbooks of toxicology and occupational medicine for a complete discussion of the numerous additional products found in the workplace that may result in occupational exposure.

Enzymatic methylation of arsenic species and other new approaches to arsenic toxicity

Arsenic metabolism has typically been studied by administering arsenate or arsenite into animals and humans and then studying the metabolites excreted in the urine. Although such studies have yielded information about the beginning and the end of the metabolic pathways for the metabolism of inorganic arsenic compounds, any statements as to the molecular mechanisms of these reactions have had to be highly speculative. Now that the rabbit and the rhesus monkey liver enzymes that transfer methyl groups from S-adenosylmethionine to arsenite and monomethlyarsonic acid have been purified and the reactions characterized, meaningful investigations of species diversity and polymorphism of these enzymes have become possible. New World animals studied thus far appear to be deficient in or totally lacking these enzymes. Old World animals, with the exception of the chimpanzee, have ample amounts of arsenite and monomethylarsonic acid methyltransferases. A hypothesis that the lack of arsenite methyltransferases may have had an evolutionary advantage for certain species is proposed.