Arsenic poisoning: sources, symptoms and what UK health agencies say

UKHSA explains that arsenic occurs naturally and is widely distributed in rocks, soil, air and water. It may be found as the metal element or as a compound, for example combined with oxygen to form arsenic trioxide. Inorganic arsenic is produced mainly as a by-product of smelting copper, lead and other metals.

It is used in making electronic components, special alloys and certain glass and ceramic products, and compounds may be used to preserve wood, though UKHSA notes there are restrictions on this use in the UK. Human activities such as coal burning, smelting, agriculture and mining can further distribute arsenic in the environment.

The presence of arsenic in the environment does not automatically lead to exposure. UKHSA stresses that to cause adverse health effects you must come into contact with it, by breathing or ingesting it, and that effects depend on the dose, route, duration and form.

According to UKHSA, in the UK arsenic levels are under stringent control and exposures in water, air and food are reduced to the lowest practical level. Food is the largest source of exposure for most people, with most dietary arsenic coming from fish in the form of organic arsenic, which is much less harmful, and UKHSA says there is no evidence that eating fish poses a health risk from arsenic.

Some parts of the world have naturally high arsenic levels in drinking water, UKHSA lists Hungary, Bangladesh, West Bengal in India and Taiwan among them. It also notes arsenic detected in some traditional medicines and herbal supplements and as an impurity in cosmetics, that cigarette smoke contains a large amount of arsenic and smoking can double the amount taken in per day, and that workers in smelting or wood preservation may be exposed, although safe limits are enforced.

UKHSA says ingesting large amounts of arsenic can damage the stomach, kidneys, liver, heart and nervous system, and in severe cases causes death. In its toxicological overview, symptoms after a large dose include nausea, vomiting, diarrhoea and abdominal pain, and acute encephalopathy.

In severe poisoning, multi-organ features develop within hours, including rhabdomyolysis, renal failure, respiratory failure, failure of vital cardiovascular and brain functions, and death. Peripheral neuropathy and skin lesions typical of chronic poisoning may appear weeks after the initial exposure, and transverse white lines may appear on the nails. Breathing air with high levels of arsenic can cause lung damage, shortness of breath, chest pain and cough.

Arsenic compounds may also be corrosive and can cause burns to the skin or eyes on contact.

UKHSA says long-term exposure to arsenic can cause changes to the skin and blood circulation. Skin lesions, including thickening of the palms and soles, warts or corns and patches of pigmentation, are thought to be the most sensitive indicator of chronic exposure to high levels.

Other features of chronic exposure include peripheral vascular effects, cardiovascular effects, peripheral neuropathy and gastrointestinal irritation. Chronic inhalation has been associated with upper respiratory tract irritation and changes to the nose lining. Chronic exposure may result in a wide range of signs and symptoms, many of them non-specific, which is one reason diagnosis can be difficult.

The International Agency for Research on Cancer classifies arsenic and inorganic arsenic compounds as carcinogenic. UKHSA says these studies were based on people exposed to high levels for a long time, for example in certain occupations or in regions where drinking water has very high levels, and that short-term exposure is likely to be associated at most with only a very small increase in cancer risk.

For pregnancy, UKHSA says that in some but not all studies of women in areas with very high arsenic in drinking water, increases in low birth weight and death of the unborn child or young infant have been seen, and that effects on the unborn child are generally more likely at levels that harm the mother. It adds that children may be more vulnerable, with some studies reporting negative impacts on intellectual development in areas with very high water levels.

UKHSA explains that arsenic is mainly excreted by the kidneys, so the concentration in urine is a good indication of recent exposure to inorganic arsenic, whereas it is cleared rapidly from the blood, limiting blood tests' usefulness, although blood should be collected with urine when acute exposure is suspected.

UKHSA notes that arsenic is excreted in urine as a mixture of species, predominantly organic arsenic, so results need careful interpretation by clinicians.

UKHSA says that if you have any health concerns regarding exposure to arsenic you should seek guidance from your GP or contact NHS 111. If someone has swallowed a large amount, is vomiting repeatedly, is confused, has difficulty breathing or has collapsed, treat it as an emergency and call 999.

If you think a private water supply, a product or a workplace is the source, tell your GP or local environmental health team so that exposure can be investigated and reduced. Treatment of confirmed poisoning is specialist hospital care directed by toxicology advice.

Suspected poisoning is handled through NHS 111, GP services and emergency departments, with specialist advice from toxicology services and UKHSA when a chemical incident is involved. UKHSA material is designed for responders and the public.

If you are worried about exposure, start with your GP, who can arrange appropriate testing and interpret results in context.