History
Arsenic exposure is usually suicidal, malicious, homicidal, or occupational. To reveal the exposure, record a careful work history on individuals with symptoms of a painful peripheral neuropathy. If the setting is not occupational, a careful epidemiologic history of those affected and those unaffected must be undertaken.
Exposure to arsine gas is usually the result of an occupational accident; in most cases, the worker presents promptly and ideally is brought in with the material safety data sheet (MSDS). One case report indicates that the presentation may be more insidious: In this report, a man in his 20s presented to an emergency department complaining of bloody urine and vomiting 34 hours after an apparent exposure to arsine in the workplace. Laboratory evaluation revealed arsenic in his blood and urine, and an industrial hygiene evaluation of his worksite was able to reproduce his exposure. [22]
Identifying unusual cases requires a careful history regarding dietary and nutritional habits, particularly the use of nutritional supplements and ayurvedic medicines, hobbies, and alcohol abuse. [23]
Often, patients with neurologic symptoms are subjected to so-called heavy metal screens by their primary care practitioners or even neurologists. Often, the laboratories used are not the standard medical reference laboratories, and the results are of questionable reliability. In other cases, the results are reported as concentration of total arsenic in urine or blood, which is not generally accepted as valuable in the determination of possible exposure or toxicity.
Physical
In inorganic arsenic poisoning, clinical effects depend on the chronicity of exposure, as follows:
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Acute exposures generally feature the choleralike gastrointestinal symptoms of vomiting (often bloody) and severe diarrhea (which may be rice-watery in character and is often bloody). Dehydration and shock may result. Mees lines (white bands across the fingernails and toenails) and alopecia may occur after several weeks.
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Individuals exposed to arsenic may have abnormalities in keratin-containing tissues such as hair and fingernails. Fingernails may display Mees lines, which are opaque horizontal lines that correlate with a period of increased arsenic exposure (see the image below); however, note that Mees lines may also result from Hodgkin lymphoma, carcinoid tumors, and chemotherapy (eg, cyclophosphamide, vincristine, doxorubicin). [24] Skin may have hypertrophic regions known as arsenical keratosis, which may be precancerous.
Mees lines, or leukonychia, are transverse white bands with no palpable ridges that appear on the fingernails as a result of arsenic poisoning, certain cancers, and treatment with certain chemotherapy agents. Courtesy of Wikimedia Commons (Author Yannick Trottier) (https://commons.wikimedia.org/wiki/File:Mees%27_lines.jpg).
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Chronic toxicity is more insidious and may manifest as a classic dermatitis (hyperkeratosis with a classic "dew drops on a dusty road" appearance) [25] or peripheral neuropathy (usually a painful paresthesia that is symmetrical and stocking-glove in distribution). Motor weakness and ascending paralysis similar to Guillain-Barré syndrome may develop.
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Multiple reports of cardiac arrhythmias exist in the literature, with abnormalities including prolongation of the QT interval, torsade de pointes, and ventricular fibrillation after acute arsenic intoxication.
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Chronic hepatic and renal damage is common with chronic exposure.
Toxicity from arsine gas exposure manifests as headache, abdominal pain, nausea vomiting, acute hemolysis, hemoglobinuric renal injury, and death. Hemoglobinuria causes the urine to appear black (see the image below), and the patient becomes rapidly obtunded and shocky. Shaking chills are often described in these patients.
"Blackwater" urine due to massive hemolysis, from a patient exposed to arsine at a gas tank cleaning operation.
Causes
Children may encounter arsenic trioxide as a rodenticide or herbicide. Examine for both arsenic and cholinesterase-inhibitor exposure. Possible transdermal absorption from exposure to pressure-treated wood, now banned for use by the US Environmental Protection Agency, has been reported.
Adults may be exposed through work in a metal foundry, mining, glass production, or the semiconductor industry.
Arsenic has been found to contaminate such common items as wine, glues, and pigments. Arsenic is commonly found in many foods both in its apparently nontoxic organic form and also in the more toxic inorganic form. Such arsenic has been reported in milk and dairy products, beef, pork, poultry, and cereal. Arsenic is also often found in rice, representing a potentially serious source of exposure in certain at-risk populations.
Arsenic exists in significant concentrations in some shallow wells dug for provision of clean water in some underdeveloped countries.
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"Blackwater" urine due to massive hemolysis, from a patient exposed to arsine at a gas tank cleaning operation.
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Mees lines, or leukonychia, are transverse white bands with no palpable ridges that appear on the fingernails as a result of arsenic poisoning, certain cancers, and treatment with certain chemotherapy agents. Courtesy of Wikimedia Commons (Author Yannick Trottier) (https://commons.wikimedia.org/wiki/File:Mees%27_lines.jpg).
