Arsenic poisoning

Arsenic poisoning, or arsenicosis, is a medical condition arising from excessive accumulation of arsenic in the body. Exposure can occur acutely over a short period or chronically over many years, with the severity of symptoms varying by dose, chemical form and route of exposure. Arsenic contamination, particularly of groundwater, represents one of the most widespread environmental health risks globally.

Clinical Manifestations

Acute arsenic poisoning presents rapidly, often within hours of ingestion. Symptoms resemble those of severe gastrointestinal illness, including intense abdominal pain, nausea, vomiting and profuse diarrhoea, which may be bloody. Substantial fluid loss can lead to hypovolaemic shock. Toxic effects extend to the cardiovascular and nervous systems, causing arrhythmias such as QT interval prolongation, heart failure, seizures, delirium, cerebral oedema and coma. Arsine gas, a highly toxic form of arsenic encountered in industrial settings, causes multisystem involvement characterised by gastrointestinal distress, weakness, respiratory difficulty, haemolysis and organ dysfunction.
Chronic poisoning develops gradually with lower doses. Dermatological changes are early indicators: hyperpigmented patches, areas of hypopigmentation and alternating dark and light patterns. Hyperkeratosis of the palms and soles is common, and some individuals develop transverse white nail bands known as Mees’ lines. Long-term exposure impairs multiple organs. Neurological manifestations include peripheral neuropathy, while hepatosplenomegaly and metabolic disturbances such as diabetes may occur. Arsenic-induced vascular injury can lead to portal hypertension and non-cirrhotic portal fibrosis. Importantly, prolonged exposure increases the risk of malignancies, particularly cancers of the skin, lung, liver, bladder and prostate, as well as angiosarcoma. Squamous cell carcinoma in situ is the most frequently observed skin cancer associated with arsenic.

Mechanism and Diagnosis

Arsenic exerts its toxicity by disrupting cellular metabolism and altering the activity of approximately 200 enzymes, many of which are involved in energy production and oxidative stress responses. Its affinity for sulphhydryl groups contributes to widespread cellular dysfunction.
Diagnosis relies on detecting elevated arsenic levels in biological samples. Urine is the preferred specimen for recent exposures, while hair and blood analyses assist in identifying longer-term or high-level exposures. Diagnostic interpretation must account for the presence of organic arsenic—derived mostly from seafood—which is considerably less toxic than inorganic forms.

Causes and Exposure Pathways

Contaminated drinking water is the primary source of chronic arsenic exposure worldwide. Groundwater arsenic levels vary widely according to geological context, from less than 1 part per billion (ppb) to several thousand ppb. Naturally occurring arsenic can leach into aquifers from mineral deposits, particularly in regions with volcanic activity or arsenic-bearing sulphide minerals. Anthropogenic contamination can also occur through mining, smelting and agricultural activities.
Water sources in Bangladesh and West Bengal exhibit some of the highest concentrations globally, with more than 200 million people worldwide exposed to unsafe levels. In the United States, arsenic is ubiquitously present in groundwater. Typical concentrations are low, but certain aquifers—particularly in western states—show significantly elevated values, in some instances exceeding 1,000 ppb. Localised geological formations, such as volcanic terrain in California or pyrite-bearing sandstone aquifers in Wisconsin, account for elevated readings. Similar risks are documented in Brazil, Cambodia, Afghanistan and parts of Australia.
Food constitutes another important exposure route. Organic arsenic, largely non-toxic, is abundant in seafood in the form of arsenobetaine and arsenocholine. Other organic species such as monomethylarsonic and dimethylarsinic acids appear in fin fish, molluscs and crustaceans at generally low levels. Arsenosugars and arsenolipids, commonly found in seaweed and some shellfish, are the subject of ongoing toxicological study. Rice is particularly susceptible to absorbing arsenic from soil and irrigation water. Although rice grown in the United States contains measurable levels, overall dietary intake remains below international safety thresholds. Several countries have implemented standards for arsenic in food, such as China’s 150 ppb limit.
Airborne arsenic contributes only a small fraction to overall exposure. Ambient concentrations vary from fractions of a nanogram per cubic metre in remote regions to tens of nanograms near industrial facilities. Past widespread use of lead arsenate pesticides has left persistent residues in former orchard areas, creating long-term soil contamination, particularly in parts of New Jersey, Washington and Wisconsin. Although many arsenic-based pesticides have been discontinued, some treated wood products continue to contain chromated copper arsenate.

Prevention and Public Health

Preventing arsenic poisoning relies primarily on ensuring access to safe drinking water. Approaches include filtering groundwater using specialised systems, sourcing water from arsenic-free aquifers, or collecting rainwater in affected regions. Public health initiatives focus on routine testing of water sources and providing communities with viable alternatives.
Environmental management includes monitoring industrial emissions, remediating contaminated soils and regulating the use of arsenic-containing substances. Public education is essential in regions where folk medicines or traditional remedies may contain arsenic.

Treatment

Evidence for specific treatments in chronic arsenic poisoning is limited. The primary management strategy involves removing the source of exposure and supporting affected organ systems. Chelation therapy with agents such as dimercaptosuccinic acid or dimercaptopropane sulfonate may be used in acute cases, although dimercaprol is generally not recommended. Management of dehydration, electrolyte imbalance and organ failure is critical in severe poisoning. Haemodialysis can assist in reducing arsenic levels in certain acute scenarios.