Arsenic Poisoning: Causes, Symptoms, Treatment & Safe Limits (original) (raw)
- Introduction
- Inorganic Arsenic
- Organic Arsenic
- Most Toxic Form
- Symptoms
- Stages
- How It Happens
- Diagnosis
- Treatment
- Prognosis
- Prevention
- Foods
- Drinking Water
- FAQs
What is arsenic?
Arsenic is a gray-appearing chemical element (atomic number 33, symbol "As" in the periodic table) also termed a metalloid. Arsenic can exist in a metallic state in three forms (yellow, black, and gray; with gray predominating) and in ionic forms. Arsenic is considered to be a heavy metal, and arsenic toxicity shares some features with poisonings by other heavy metals. Historically, arsenic has been used as a medicinal agent, a pigment, a pesticide, and an agent with intent to harm (use with criminal intent). Up until 2003, arsenic (in the form of chromated copper arsenate) was used in the U.S. as a treatment to prevent insect infestation of wood used in buildings. In 2003 the use of this compound was banned by the U.S. Environmental Protection Agency. The U.S. Occupational Safety and Health Administration (OSHA) has established a permissible exposure limit (PEL) for arsenic at 10 micrograms per cubic meter (μg/m³) of workplace air, averaged over an 8-hour shift within a 40-hour work week.
Arsenic is mixed with copper or lead to strengthen alloys containing these materials. Arsenic and some of its compounds react with proteins, mainly the thiol portions, and uncouples the process of oxidative phosphorylation, thus inactivating most cellular functions. Consequently, arsenic and some of the substances it combines with are deadly poisons to most biological systems, except for a few bacterial species. Arsenic is used in making insecticides and weed killers. Arsenic is also thought to be carcinogenic, meaning that it has the potential to cause cancer.
Arsenic can be found as a contaminant in food and water sources. Shellfish and other seafood, as well as fruits, vegetables, and rice; are the foods most commonly contaminated. Arsenic poisoning typically occurs as a result of industrial exposure, from contaminated wine or illegally distilled spirits, or in cases of malicious intent.
What is inorganic arsenic?
Inorganic arsenic is a metallic or metalloid element that forms a number of poisonous compounds. In industry, it can be found in a gaseous form termed arsine gas, which is very toxic when inhaled. Inorganic arsenic is found in nature at low levels mostly compounded with oxygen, chlorine, and sulfur. These are called inorganic arsenic compounds. Inorganic arsenic compounds are much more poisonous to most biological systems (animals, plants, humans) than organic arsenic (see below).
Inorganic arsenic occurs in nature in the soil, copper and lead ore deposits, and water, but usually in low concentrations. However, it can become more concentrated when industrial processes use it to make wood preservatives, metal compounds, or organic arsenic-containing compounds such as insecticides, weed killers, and other compounds. If such compounds are burned, inorganic arsenic can be released into the air and later settle on the ground or in water and either remain in the inorganic form or combine with organic material.
What is organic arsenic?
Organic arsenic is any compound that is made from a chemical combination of the element arsenic with any organic compound (compounds containing a large amount of carbon). These are often termed arsenical organic compounds.
Most frequently, organic arsenic is used in making insecticides, weed killers, and other compounds. Organic arsenic usually is not poisonous to humans but may be poisonous to humans in high concentrations. In general, organic arsenic is usually far less poisonous than inorganic arsenic.
What is the most toxic form of arsenic?
Inorganic arsenic compounds, such as arsenite (arsenic trioxide) and arsenate (arsenic pentoxide), are regarded as the most toxic forms of arsenic. These forms are more toxic than organic arsenic compounds found in nature, such as arsenobetaine and arsenocholine, which are typically less harmful to humans. Inorganic arsenic compounds are highly toxic because they are readily absorbed by the body and can disrupt cellular functions, leading to severe health effects such as cancer, skin lesions, cardiovascular disease, and neurological disorders.
What are arsenic poisoning symptoms?
People can be exposed to arsenic by inhaling it, by consuming contaminated foods, water, or beverages, or by skin contact. We are normally exposed to trace amounts of arsenic in the air, water, and foods. People may be exposed to higher levels if they live near industrial areas currently or formerly contaminated with arsenic compounds. Areas with known high concentrations of arsenic in the drinking water are also associated with greater exposure.
Acute or immediate symptoms of a toxic level of exposure to arsenic may include the following:
- Vomiting
- Abdominal pain
- Diarrhea
- Dark urine (termed black water urine)
- Dehydration
- Cardiac problems
- Hemolysis (destruction of red blood cells)
- Vertigo
- Delirium
- Shock
- Death
What are the long-term effects of arsenic poisoning? Long-term exposures to arsenic lower than toxic levels can lead to skin changes (darkening or discoloration, redness, swelling, and hyperkeratosis, which refers to skin bumps that resemble corns or warts). Whitish lines (Mees' lines) may appear in the fingernails. Both sensory and motor nerve defects can develop. Additionally, liver and kidney function may be affected.
Arsenic exposure over the long term has also been associated with the development of certain cancers, and arsenic has been classified as a carcinogen by the Environmental Protection Agency (EPA). Studies of people in parts of Southeast Asia and South America where there has been a high level of arsenic in the drinking water have reported an increased risk of developing cancers of the bladder, kidney, lung, and skin. Organic arsenic compounds are not as toxic as inorganic compounds and are not believed to be linked to cancer.
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What are the 4 stages of arsenic poisoning?
Arsenic poisoning occurs in several stages, each characterized by specific symptoms and health effects as the exposure progresses. These stages reflect both acute (short-term) and chronic (long-term) exposure scenarios, with chronic exposure being more common due to arsenic's cumulative toxicity. The four stages of arsenic poisoning include:
I. Initial symptoms:
- Symptoms: The initial stage of arsenic poisoning often includes nonspecific symptoms such as nausea, vomiting, abdominal pain, and diarrhea. These symptoms may appear within hours to a few days after exposure to a high dose of arsenic.
- Duration: This stage can last from a few hours to several days, depending on the level and duration of exposure.
II. Subacute manifestations:
- Symptoms: As arsenic poisoning progresses, additional symptoms may develop, including skin changes such as hyperpigmentation (darkening of the skin), hyperkeratosis (thickening of the skin), and the appearance of characteristic skin lesions like "raindrop pigmentation."
- Other effects: Neurological symptoms such as peripheral neuropathy (tingling, numbness, and pain in extremities) and cardiovascular effects (such as hypertension) may also begin to manifest.
- Duration: This stage can extend over weeks to months, depending on the individual's exposure history.
III. Chronic symptoms:
- Symptoms: Chronic arsenic poisoning can lead to more pronounced and widespread symptoms. These include persistent skin changes such as chronic dermatitis, skin cancer (especially squamous cell carcinoma), and systemic effects such as respiratory problems, diabetes, and cardiovascular diseases.
- Duration: This stage can persist indefinitely, as chronic arsenic exposure leads to cumulative health effects.
IV. Terminal manifestations:
- Symptoms: In severe cases of chronic arsenic poisoning, terminal manifestations may include multiorgan failure, severe cardiovascular complications, and an increased risk of various cancers (lung, bladder, liver).
- Prognosis: Without intervention, terminal manifestations can lead to death.
- Duration: The duration of this stage varies depending on the individual's overall health status and the extent of arsenic exposure.
How does arsenic poisoning occur?
How does arsenic poisoning occur?
Arsenic is a naturally occurring element found in soil, water, and air, and human exposure can occur through various routes including ingestion, inhalation, or skin contact.
- Ingestion:
- Contaminated water: Drinking water contaminated with arsenic is a significant source of exposure, especially in areas where groundwater naturally contains high levels of arsenic. Ingestion of contaminated water over a long period can lead to chronic arsenic poisoning.
- Food: Arsenic can accumulate in certain foods, especially rice, vegetables, and seafood (fish and shellfish), depending on the arsenic levels in the soil or water where these foods are grown or harvested.
- Medicinal use: Historically, arsenic compounds were used in traditional medicines and some pharmaceuticals. Improper or excessive use of these compounds could lead to arsenic poisoning.
- Inhalation:
- Occupational exposure: Workers in industries such as mining, smelting, wood preservation, and electronics manufacturing may inhale arsenic-containing dust or fumes, leading to acute or chronic arsenic poisoning.
- Environmental exposure: Inhalation of airborne arsenic particles from industrial emissions or contaminated soil can also contribute to arsenic exposure.
- Skin contact:
- Occupational exposure: Workers handling arsenic-containing materials or products (pesticides, wood preservatives) may absorb arsenic through their skin, leading to toxicity over time.
- Environmental exposure: Arsenic-contaminated soil or water can also lead to dermal exposure, particularly in agricultural settings or areas with industrial contamination.
- Other routes:
- Smoking: Tobacco smoke may contain arsenic, contributing to exposure for smokers and those exposed to passive smoking.
- Environmental sources: Arsenic can enter the environment through natural processes (volcanic activity, erosion) and human activities (industrial processes, mining), leading to widespread contamination of air, water, and soil.
How is arsenic poisoning diagnosed?
The history of the patient is very important, as exposures are most often from industrial accidents; so, other people (coworkers, rescue personnel) may be exposed and not realize they may also have some risk. People exposed to toxic levels of arsenic may have breath and urine that smells like garlic as a clue to their diagnosis. Most doctors that suspect arsenic poisoning (or other metal or metalloid poisonings) will request lab studies including blood cell counts and serum electrolytes such as calcium and magnesium; if there is evidence of hemolysis (blood cell destruction), a type of screening for a potential blood transfusion is done.
There are rapid urine "spot" tests available to diagnose elevated levels of arsenic, but they usually don't distinguish between organic and inorganic arsenic. The patient's blood and urine will be sent for analysis for arsenic; a result of > 50 micrograms/L is considered elevated, but acute toxic exposures may result in levels 5 to 100 times or more than those that are considered "elevated."
A speciation test (determines levels of inorganic versus organic arsenic) is required in all cases where total urine arsenic is elevated since inorganic arsenic is so toxic. Electrocardiograms (ECG, EKG) and nerve conduction tests are often done in all types of suspected arsenic exposure. Tests for other toxins or toxic overdoses (for example, Tylenol ingestion) may also be done.
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How is arsenic poisoning treated?
Acute toxic inorganic arsenic exposure and arsine gas exposure can rapidly result in death, and there are only a few ways to possibly save the patient's life. Hemodialysis can remove arsenic from the bloodstream, but only before it binds to the tissues so there is only a short time window for this treatment to work. Similarly, arsine binds to and causes rapid destruction of red blood cells, so blood transfusions and exchange transfusions may help the patient.
In addition, if the arsenic was ingested, stomach or bowel irrigation may be attempted, but there is no good data to indicate these will be successful. Consultation with a nephrologist and a toxicologist as soon as possible is recommended; other consultants may need to be called (hematologist, psychiatrist, or others).
Chelation therapy (the use of drugs that selectively bind and effectively inactivate substances) is usually begun quickly through an intravenous line. The drug and the bound arsenic are then excreted through the urine. The chelation drug of choice is Dimercaprol (one brand name is Bal in Oil). Succimer (DMSA) has also been used successfully, and Dimerval (DMPS) may also work as a chelator, but it is not readily available in the U.S.
What is the prognosis (outcome) of arsenic poisoning?
If the patient survives an acute toxic exposure, most will develop some degree of nerve damage to the peripheral nerves (sensory and motor disturbances). Many survivors may have cardiac, liver, renal, and skin problems; the prognosis is fair to poor. Chronic poisoning and organic arsenic exposure have better outcomes with fewer and less severe problems.
Is there a way to prevent arsenic poisoning?
Preventing arsenic poisoning involves several key strategies aimed at minimizing exposure to arsenic-contaminated sources. By implementing the following preventive measures, the risk of arsenic poisoning can be reduced:
- Water testing and treatment: Regularly test well water and other drinking water sources for arsenic levels. Use appropriate filtration systems or treatment methods, such as reverse osmosis, to reduce arsenic concentrations below safe thresholds.
- Water management strategies: Replace high-arsenic sources, such as groundwater, with microbiologically safe, low-arsenic alternatives, such as rainwater and treated surface water. Use low-arsenic water for drinking, cooking, and irrigation while reserving high-arsenic water for activities such as bathing and washing clothes.
- Food safety practices: Be aware of potential arsenic sources in food, particularly in rice and seafood. Choose a diverse diet and various sources of grains and seafood to reduce arsenic intake.
- Industrial and occupational safety: Follow safety guidelines and regulations in industrial settings to minimize exposure to airborne arsenic particles. Proper ventilation and personal protective equipment (PPE) can help reduce inhalation risks.
- Maintaining personal hygiene: Wash hands and exposed skin thoroughly after contact with soil or other potentially contaminated surfaces, especially before eating.
- Environmental monitoring: Stay informed about local environmental reports and health advisories regarding arsenic contamination in soil, water, and air. Take precautions accordingly to avoid exposure.
What foods are commonly associated with arsenic poisoning?
People may be exposed through work in a metal foundry, mining, glass production, the semiconductor industry, in criminal attempts at murder by poisoning, suicide attempts, and as biological warfare agents.
- Arsenic has been found to contaminate such common items as wine, glues, and pigments.
- Arsenic is commonly found in many foods both in its relatively nontoxic organic form and in the more toxic inorganic form. Consequently, such foods need to be tested for both inorganic and organic arsenic levels.
- 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 (especially children).
- Many water sources in the world have high levels of arsenic in them, both due to normal arsenic leaching out of the ground and from mining and industrial waste.
Recent examples of concerns about arsenic have surfaced because of its presence in apple juice. In most studies, various sources of apple juice tested by the government and consumer labs have found that most (over 95% tested) contain a very small amount of arsenic (less than 10 parts per billion) and are safe to drink (in contrast to a TV show that raised alarms about consuming apple juice). However, the FDA announced in June 2023 that new standards would apply and any juice that contained 10 or more parts per billion (the same level set for safe groundwater) would not be permitted to be sold in the US. This is lower than the previously approved level of fewer than 23 parts per billion approved in 2008. Nonetheless, other groups suggest that should only be approved if it contains less than 3 parts per billion of arsenic.
Two other sources of arsenic, especially of some concern for children, are groundwater and rice that is grown in such groundwater. Rice is a common food for children but to date, there are no regulations about the levels of arsenic that are considered safe for consumption. In 2013, the CDC recommended only about 2 cups of cooked rice per individual (adult) per week. According to guidance provided by the FDA in August 2020, the allowable limit for inorganic arsenic in rice cereal for infants is set at 100 micrograms per kilogram (µg/kg), equivalent to 100 parts per billion (ppb).
Efforts are ongoing to establish clearer regulations and guidelines to protect consumers, especially vulnerable populations, from the potential health risks associated with arsenic in food and beverages.
Can drinking water be contaminated with arsenic?
Drinking water can be contaminated with arsenic, especially in areas where natural geological formations release arsenic into groundwater. Human activities such as mining, industrial processes, and the use of arsenic-containing pesticides can also contribute to arsenic contamination in water sources. Regular testing and appropriate treatment methods are essential to ensure safe drinking water.
Frequently asked questions
- How can you test for arsenic in your home? To test for arsenic in your home, use commercially available arsenic kits specifically designed for water or soil testing. These kits usually include test strips or reagents that change color in the presence of arsenic. Follow the instructions carefully to collect a sample and perform the test accurately. If you suspect higher levels of arsenic, consider consulting a professional environmental testing service for more precise results and guidance.
- What levels of arsenic exposure are considered dangerous? Exposure to arsenic levels above 10 micrograms per liter (µg/L) in drinking water is considered dangerous and can pose significant health risks over time. Long-term exposure to high levels of arsenic has been linked to certain health problems, including skin lesions, cardiovascular diseases, and cancers of the skin, bladder, and lungs. It is crucial to ensure arsenic levels in drinking water and soil are regularly monitored to mitigate health risks.
- How can arsenic enter the body? Arsenic can enter the body through ingestion of contaminated food and water, inhalation of airborne particles (either in industrial settings or from burning arsenic-containing materials), and dermal contact with contaminated soil or water during activities such as bathing or swimming. Once absorbed into the body, arsenic can accumulate in tissues and organs, resulting in diverse health effects over time.
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Medically Reviewed on 8/16/2024
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