Arsenic is typically considered a heavy metal and shares many toxic characteristics with the other heavy metals (eg, lead, mercury). Arsenic is ubiquitous in the environment. It ranks 20th in abundance in the earth's crust, 14th in seawater, and 12th in the human body. In nature, arsenic exists in the metallic state in 3 allotropic forms (alpha or yellow, beta or black, gamma or grey) and several ionic forms.
Arsenic has been used as a medicinal agent, a pigment, a pesticide, and an agent of criminal intent. In the form of chromated copper arsenate (CCA), it was used until recently as part of the treatment to render architectural wood immune to pest infestation. This product was banned for use in the United States by the Environmental Protection Agency (EPA) in 2003. A great deal of the treated wood continues to exist in the form of decks and other structures exposed to the elements. Data suggest that a significant quantity of arsenic may leach out from such wood into landfills and into the interiors of homes with existing CCA-treated decks.The durability of the CCA-treated wood suggests that such exposures may continue for decades. There is evidence in the rodent model that exposure to this compound, CCA, may produce significant renal pathology. Today, arsenic is primarily used in the production of glass and semiconductors.
Arsenic may be found as a water or food contaminant, particularly in shellfish and other seafood, and often contaminates fruits and vegetables, particularly rice.
Today, arsenic poisoning occurs through industrial exposure, from contaminated wine or moonshine, or because of malicious intent. The possibility of heavy metal contamination of herbal preparations and so-called nutritional supplements must also be considered. There has been a resurgence of interest in arsenic as a medicinal agent for treatment of acute promyelocytic leukemias, multiple myeloma, myelodysplastic syndromes, and assorted resistant solid tumors.
An association between exposure to arsenic and the development of Alzheimer disease has been proposed. In addition, an apparent link exists between arsenic exposure and gestational diabetes and potential long-term effects on the infants born to mothers consuming arsenic-contaminated water among other during pregnancy.
Because arsenic has been involved in geopolitics, an estimated 100 million people are at risk of exposure to unacceptable arsenic levels in either well water or ground water. Numerous "outbreaks" of excessive arsenic in water and food from an assortment of natural and anthropological causes have occurred. This has become a major public health issue in the developing world, primarily Bangladesh and surrounding countries, where many thousands of individuals have precancerous arsenic-related disease.
Chronic arsenic toxicity
Chronic arsenic toxicity (arsenicosis) due to drinking of arsenic contaminated ground water is a
major environmental health hazard throughout the world including India. A lot of new information
is emerging from extensive research on health effects of chronic arsenic toxicity (CAT) in humans
during the last two decades. Available literature has been reviewed to highlight the problem including
its malignancies. Pigmentation and keratosis are the specific skin lesions characteristics of CAT.
CAT also produces various systemic manifestations over and above skin lesions, important ones
being chronic lung disease like chronic bronchitis, chronic obstructive pulmonary disease and
bronchiectasis, liver disease like non-cirrhotic portal fibrosis and other diseases like polyneuropathy,
peripheral vascular disease, hypertension and ischeamic heart disease, diabetes mellitus, non-pitting
oedema of feet/hands, weakness and anaemia. Cancer of skin, lung and urinary bladder are important
cancers associated with chronic arsenic toxicity. Stoppage of drinking of arsenic contaminated water
is the main stay in the management of arsenicosis as specific chelation therapy has limited value.
Early skin cancer, detectable by regular active surveillance, is curable. In addition to dermatological
features, CAT produces protean clinical manifestations. Treatment of arsenicosis is unsatisfactory
and is mostly symtomatic.
Acute or immediate symptoms of a toxic level of exposure to arsenic may include the following:
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.
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 which are considered "elevated." A speciation test (determines levels of inorganic versus organic arsenic) is required in all cases in which total urine arsenic is elevated since inorganic arsenic is so toxic. Electrocardiograms (ECG, EKG) and nerve conduction tests are often done in any type of suspected arsenic exposure. Tests for other toxins or toxic overdoses (for example, Tylenol ingestion) may also be done.
Treatment
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 selective bind and effectively inactivate substances) is usually begun quickly through an intravenous line. The drug and the bound arsenic is then excreted through the urine. The chelation drug of choice is Dimercaprol (also termed BAL in oil); Succimer (DMSA) has also been used successfully, and Dimerval (DMPS) may also work as a chelator.
Precaution
eople 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 a biological warfare agent.
Courtesy : medicinenet.com
Arsenic has been used as a medicinal agent, a pigment, a pesticide, and an agent of criminal intent. In the form of chromated copper arsenate (CCA), it was used until recently as part of the treatment to render architectural wood immune to pest infestation. This product was banned for use in the United States by the Environmental Protection Agency (EPA) in 2003. A great deal of the treated wood continues to exist in the form of decks and other structures exposed to the elements. Data suggest that a significant quantity of arsenic may leach out from such wood into landfills and into the interiors of homes with existing CCA-treated decks.The durability of the CCA-treated wood suggests that such exposures may continue for decades. There is evidence in the rodent model that exposure to this compound, CCA, may produce significant renal pathology. Today, arsenic is primarily used in the production of glass and semiconductors.Arsenic may be found as a water or food contaminant, particularly in shellfish and other seafood, and often contaminates fruits and vegetables, particularly rice.Today, arsenic poisoning occurs through industrial exposure, from contaminated wine or moonshine, or because of malicious intent. The possibility of heavy metal contamination of herbal preparations and so-called nutritional supplements must also be considered. There has been a resurgence of interest in arsenic as a medicinal agent for treatment of acute promyelocytic leukemias, multiple myeloma, myelodysplastic syndromes, and assorted resistant solid tumors.
An association between exposure to arsenic and the development of Alzheimer disease has been proposed. In addition, an apparent link exists between arsenic exposure and gestational diabetes and potential long-term effects on the infants born to mothers consuming arsenic-contaminated water among other during pregnancy.
Because arsenic has been involved in geopolitics, an estimated 100 million people are at risk of exposure to unacceptable arsenic levels in either well water or ground water. Numerous "outbreaks" of excessive arsenic in water and food from an assortment of natural and anthropological causes have occurred. This has become a major public health issue in the developing world, primarily Bangladesh and surrounding countries, where many thousands of individuals have precancerous arsenic-related disease.
Chronic arsenic toxicity
Chronic arsenic toxicity (arsenicosis) due to drinking of arsenic contaminated ground water is amajor environmental health hazard throughout the world including India. A lot of new information
is emerging from extensive research on health effects of chronic arsenic toxicity (CAT) in humans
during the last two decades. Available literature has been reviewed to highlight the problem including
its malignancies. Pigmentation and keratosis are the specific skin lesions characteristics of CAT.
CAT also produces various systemic manifestations over and above skin lesions, important ones
being chronic lung disease like chronic bronchitis, chronic obstructive pulmonary disease and
bronchiectasis, liver disease like non-cirrhotic portal fibrosis and other diseases like polyneuropathy,
peripheral vascular disease, hypertension and ischeamic heart disease, diabetes mellitus, non-pitting
oedema of feet/hands, weakness and anaemia. Cancer of skin, lung and urinary bladder are important
cancers associated with chronic arsenic toxicity. Stoppage of drinking of arsenic contaminated water
is the main stay in the management of arsenicosis as specific chelation therapy has limited value.
Early skin cancer, detectable by regular active surveillance, is curable. In addition to dermatological
features, CAT produces protean clinical manifestations. Treatment of arsenicosis is unsatisfactory
and is mostly symtomatic.
What are the symptoms of arsenic poisoning?
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 and water, and in foods. People may be exposed to higher levels if they live near industrial areas that currently or formerly contained 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
Long-term exposure to arsenic at lower than toxic levels can lead to skin changes (darkening or discoloration, redness, swelling and hyperkeratosis (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. Diagnosing
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 have some risk also. 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 (or other metal or metalloid poisonings) will request lab studies such as blood cell counts and serum electrolytes such as calcium and magnesium; if there is evidence of hemolysis (blood cell destruction), a type and 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 which are considered "elevated." A speciation test (determines levels of inorganic versus organic arsenic) is required in all cases in which total urine arsenic is elevated since inorganic arsenic is so toxic. Electrocardiograms (ECG, EKG) and nerve conduction tests are often done in any type of suspected arsenic exposure. Tests for other toxins or toxic overdoses (for example, Tylenol ingestion) may also be done.
Treatment
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 selective bind and effectively inactivate substances) is usually begun quickly through an intravenous line. The drug and the bound arsenic is then excreted through the urine. The chelation drug of choice is Dimercaprol (also termed BAL in oil); Succimer (DMSA) has also been used successfully, and Dimerval (DMPS) may also work as a chelator.
Precaution
eople 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 a biological warfare agent.
- 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 also in the more toxic inorganic form. Consequently, such foods need to be tested for both inorganic and organic arsenic levels.
- Such 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 human–caused mining and industrial waste.
Courtesy : medicinenet.com
