Arsenic poisoning

What is arsenic poisoning?

Arsenic poisoning is a condition that is caused by elevated levels of arsenic in the body. Arsenic is widely used in modern industry, especially in the production of pesticides, herbicides, wood preservatives, and semiconductors. The sources of arsenic, such as contaminated water, air, soil, rocks and food, can cause serious human diseases.¹

Arsenic is a heavy metal which is a natural component of the earth's crust. Arsenic poisoning can occur by ingestion, inhalation and dermal absorption. Trivalent arsenic is well absorbed through the skin and is 60 times more toxic than pentavalent arsenic, which is well absorbed by the gut.² Arsine gas is highly toxic.

Toxicity is due to arsenic's effect on many cell enzymes, which affect metabolism and DNA repair. Arsenic is excreted in urine but can also accumulate in many body tissues.³

Arsenic is currently used to treat acute promyelocytic leukaemia and other myeloproliferative disorders.⁴

In Victorian times arsenic was famous as a homicidal or suicidal poison; it is now thankfully much harder to obtain. Health and safety at work have also improved so that, in the UK, both acute and chronic arsenic poisoning are rare. However arsenic contamination affects hundreds of millions of people globally.⁵

Geological contamination of underground water supplies occurs in parts of the world, causing chronic exposure to millions of people.^{6 7}

These include:

• Arsenic contaminated drinking water.

• Some ayurvedic medicines. Some Chinese herbal medicines. Both as intended ingredient and as contaminant.

• Pesticides,⁸ herbicides and fungicides - no longer licensed in the UK.

• Wood preservatives.

• Ceramic enamels.

• Paints.

• Tobacco.

• Burning of fossil fuels - arsenic is a contaminant.

• 'Moonshine' - illicitly distilled high-proof alcohol.⁹

Occupational exposure¹⁰

This can occur in:

• The smelting and plating industries: arsenic is a byproduct of ores containing lead, gold, zinc, cobalt and nickel.¹¹

• The microelectronics industry: gallium arsenide is used in some semi-conductor computer chips.

• Coal power plants.

• Manufacture of glass and fireworks.

• Use of pesticides.

• Contact with wood treated with arsenic as a preservative.

Note that organic arsenics found in fish and seafood are non-toxic and not a cause of arsenic poisoning. Arsenic solutes are tasteless, whilst arsine gas is odourless and colourless.

Acute arsenic poisoning symptoms^{2 3}

Arsenic poisoning symptoms usually start within 30 minutes to two hours after exposure and affect every body system. Ingestion of high amounts of arsenic is typically followed by a severe gastroenteritis, a metallic taste in the mouth, garlic odour and hypersalivation. There is a characteristic sequence of multi-organ failure, with neurological symptoms (within hours) and cardiac features, succeeded by adult respiratory distress syndrome and renal/liver dysfunction. Marrow suppression develops after a few days to weeks in survivors, as does alopecia and an ascending motor neuropathy.

Details of acute arsenic poisoning features

• Metallic taste in the mouth.

• Garlic odour - often present in breath and body tissues.

• Gastrointestinal (GI):

  • Hypersalivation, abdominal pain, vomiting, profuse watery diarrhoea leading to hypovolaemic shock.

  • Trivalent arsenic is corrosive - may cause oral burns, dysphagia and GI bleeding.

• Cardiovascular:

  • Toxic cardiomyopathy.

  • Dehydration.

  • ECG changes including ST-segment changes, prolonged QT interval, ventricular tachycardia, torsades de pointes and ventricular fibrillation.

  • Gangrene of extremities.

• Respiratory:

  • Pulmonary oedema, adult respiratory distress syndrome and acute respiratory failure.

  • Inhaled arsenic causes irritation, bronchospasm and pulmonary oedema.

• Renal and hepatic:

  • Haematuria or haemoglobinuria (from acute haemolysis), proteinuria, acute tubular necrosis with acute kidney injury.

  • Jaundice, hepatomegaly, pancreatitis.

• Neurological:

  • CNS depression, encephalopathy and coma.

  • Seizures.

  • Toxic polyneuropathy with irritation of the nerve trunks.

• Haematological:

  • Acute haemolysis.

  • Bone marrow suppression.

  • Basophilic stippling and rouleaux formation may be seen on a blood film.

• Skin: rashes.

Chronic arsenic poisoning symptoms^{2 3 6 10}

Chronic arsenic exposure through drinking water leads to an increase in mortality which is directly related to the dose of arsenic exposure.⁷

Main clinical features and possible complications

• Skin lesions:

  • Skin lesions are the most common effect of chronic exposure.

  • They typically start about ten years after first exposure.

  • Keratoses on the palms and soles are characteristic.

  • Mees' lines (transverse white lines on nails).
    

    Mees' lines post-chemotherapy treatment

    

    © Yannick Trottier, CC BY-SA 3.0, via Wikimedia Commons

  • Hyperpigmentation (especially on the arms and upper chest) - diffuse dark areas or 'raindrop' pigmentation.

  • Also, exfoliative dermatitis, alopecia, conjunctivitis, corneal ulceration.

• GI:

  • Anorexia, weight loss, abdominal pain, diarrhoea.

  • Jaundice, hepatomegaly; development of portal fibrosis and cirrhosis.

• Cardiac/respiratory:^{12 13}

  • Coronary heart disease, increased further in those who also smoke.

  • Myocarditis, pericarditis.

  • Hypertension.

  • Peripheral arterial disease.

  • Restrictive or obstructive lung disease.

  • Effects in children are seen after an average of seven years of exposure.

• Haematological:

  • Pancytopenia,

  • Aplastic anaemia.

• Neurological:

  • Peripheral neuropathy (sensory and motor at 1-3 weeks).

  • Muscle fasciculation and wasting.

  • Ataxia.

• Diabetes - increased risk.

• There is mixed evidence of adverse pregnancy outcomes including still birth, miscarriage and teratogenicity among studies.

• Cancer - increased risk of cancers of the skin, lung, bladder and kidney, liver and prostate.¹⁴¹⁵¹⁶

History

• Arsenic exposure is usually occupational or environmental but can result from deliberate poisoning.¹⁷

• Take an occupational and travel history.

• Other history: hobbies, unusual forms of alcohol or diet supplements, herbal medicines.

Other forms of heavy metal poisoning - for example, lead. Botulism, gastroenteritis and haemolytic uraemic syndrome. The skin lesions may look like other forms of dermatitis.

Acute arsenic poisoning diagnosis²

• Monitoring - for least four hours after suspected ingestion: pulse, blood pressure, respiratory rate, oxygen saturation and ECG, urine output.

• Haematology, biochemistry and arterial blood gases - as for any acutely ill patient.

• Urinalysis.

• ECG.

• Arsenic levels in blood and urine (see box below for normal levels).

• CXR and plain abdominal X-ray (inorganic arsenic compounds are radio-opaque).

Chronic arsenic poisoning diagnosis

• Urinary concentrations are useful in chronic exposure.²

• Hair samples.

• Arsenic levels in drinking water (high levels of arsenic in drinking water in conjunction with relevant clinical features are useful for diagnosis in some settings).

• Investigation and screening for complications may be appropriate (for example, look for diabetes, hypertension).

Management of acute arsenic poisoning²

In the UK, contact Toxbase® for detailed advice. The following immediate principles apply.

• Remove the patient from the source of arsenic; if there is skin contamination, wash with copious water; seal contaminated clothing.

• Resuscitate ('ABC' principles).

• Management is done in hospital and consists of supportive treatment (usually in ITU), possible removal by gastric lavage and management of the complications of arsenic poisoning.

Management of chronic arsenic poisoning

• Provide arsenic-free drinking water, to reduce the risk of further disease developing. Anecdotal evidence suggests that mild-moderate keratoses may improve with cessation of exposure.

• Chelation therapy studies have demonstrated mixed evidence regarding the benefit after chronic exposure. Combinations of chelating agents may prove beneficial but require further study.^{18 19 20} It is of no use if exposure to arsenic continues.

• Co-administered micronutrients and antioxidants given with chelating agents may be beneficial, especially in undernourished populations.¹⁸

• Certain plant compounds may help in chronic exposure. This may be due to antioxidative properties of the plant. Further study is required.^{18 21}

• Skin care for keratoses.

• Screen and treat for complications - for example, diabetes, hypertension.

• Other household members:

  • Check other members of the family, as they may also have been exposed.

  • Pregnancy and breastfeeding: arsenic is probably transferred to the baby via the placenta and breast milk.³

• The prognosis of arsenic poisoning varies with the amount and rate of arsenic ingestion.

• Effects and complications can occur at different times after exposure - from days to years later.

Provision of uncontaminated water for all is essential. WHO guidelines advise that a value of <10 mcg/L of arsenic in drinking water is a realistic target but with the proviso to keep concentrations as low as possible.⁶This has not been achieved worldwide.