Arsenic poisoning

Arsenic poisoning is a toxicologic disorder that can produce neuropsychiatric and multisystemic manifestations, with clinical features varying according to the form, dose, route, and duration of exposure. A distinctive presentation may include the combination of behavioural or personality change, painful peripheral neuropathy, characteristic skin or nail changes, and a relevant environmental, occupational, dietary, or medication-related exposure.

Exposure clues include occupational or environmental exposure to inorganic arsenic, particularly through metal smelting or processing, mining, pesticide or agricultural work, and other industrial settings. Chronic exposure may also occur through naturally contaminated groundwater or food, particularly in regions with high environmental arsenic levels, as well as through certain traditional or herbal medicines. Inhalational exposure to arsenic-containing dusts or fumes and ingestion of arsenic-containing substances are important routes of exposure.

It can present with psychiatric features such as irritability, emotional lability, anxiety, depression, insomnia, impaired concentration, cognitive impairment, and personality or behavioural change. Psychotic symptoms, including hallucinations and delusional or paranoid phenomena, have also been reported, although these are uncommon and the available literature does not consistently establish to what extent they may occur outside the context of delirium.

Other characteristic features include painful distal sensory symptoms, paresthesias, numbness and, with more substantial exposure, a symmetrical sensorimotor peripheral neuropathy that may progress to weakness or an ascending neuropathic syndrome resembling Guillain–Barré syndrome. Encephalopathy, seizures, confusion, and other central neurological manifestations may occur, particularly with acute or severe poisoning.

From a multisystemic lens perspective, clinical features in other body systems include (but are not limited to):

• Cardiovascular: Hypotension, cardiac arrhythmias and QT prolongation; severe acute poisoning may cause cardiovascular collapse.

• Gastrointestinal: Abdominal pain, nausea, vomiting and diarrhea; severe acute poisoning may cause hemorrhagic gastroenteritis.

• Hematologic: Anemia, leukopenia, thrombocytopenia and, in severe poisoning, pancytopenia or other bone marrow suppression.

• Dermatologic: Diffuse hyperpigmentation, including characteristic “rain-drop” pigmentation, palmar or plantar hyperkeratosis, and transverse white lines across the nails (Mees' lines).

Early diagnosis is important because arsenic poisoning can cause persistent or irreversible neurological injury and, depending on the form and severity of exposure, significant gastrointestinal, cardiovascular, hematologic, renal, or other systemic complications. Prompt recognition allows removal from the exposure source, appropriate toxicologic assessment, and consideration of chelation therapy when indicated.