What is Arsenic?
Arsenic is a chemical element with the symbol As and atomic number 33.
Arsenic is a metalloid. It has various allotropes, but only the gray form, which has a metallic appearance, is important to the industry.
How was arsenic discovered?
Arsenic compounds were mined by the early Chinese, Greek, and Egyptian civilizations, they probable discovered its toxic properties later on. It is believed that Albertus Magnus obtained the element in 1250 A.D. who obtained it by heating soap together with orpiment (arsenic trisulphide, As2S3).
Uses of Arsenic
The primary use of arsenic is in alloys of lead (for example, in car batteries and ammunition).
It is also used industrially in the processing of glass, pigments, textiles, paper, metal adhesives, wood preservatives. It can be used to hide tanning process and, to a limited extent, in pesticides, feed additives, and pharmaceuticals.
A few species of bacteria can use arsenic compounds as respiratory metabolites. Trace quantities of arsenic are an essential dietary element in rats, hamsters, goats, chickens, and presumably other species.
People who smoke tobacco can also be exposed to the natural inorganic arsenic content of tobacco because tobacco plants can take up arsenic naturally present in the soil. Also, in the past, the potential for elevated arsenic exposure was much greater when tobacco plants used to be treated with lead arsenate insecticide.
How do you get arsenic?
Arsenic is a natural component of the earth’s crust and is widely distributed throughout the environment in the air, water, and land. It occurs in many minerals, usually in combination with sulfur and metals, but also as a pure elemental crystal.
It is highly toxic in its inorganic form.
What contains arsenic?
People are exposed to elevated levels of inorganic arsenic through drinking contaminated water, using contaminated water in food preparation and irrigation of food crops, industrial processes, eating contaminated food and smoking tobacco.
Fish, shellfish, meat, poultry, dairy products, and cereals can also be dietary sources of arsenic, although exposure from these foods is generally much lower compared to exposure through contaminated groundwater. In seafood, arsenic is mainly found in its less toxic organic form.
Naturally occurring sources of human exposure include volcanic ash, weathering of minerals and ores, and mineralized groundwater.
Arsenic is absorbed by all plants but is more concentrated in leafy vegetables, rice, apple and grape juice, and seafood.
An additional route of exposure is the inhalation of atmospheric gases and dust.
During the Victorian era, arsenic was widely used in home decor, especially wallpapers.
Occurrence in drinking water
In the United States, arsenic is most commonly found in the groundwater of the southwest.
Parts of New England, Michigan, Wisconsin, Minnesota and the Dakotas are also known to have significant concentrations of arsenic in groundwater.
Is arsenic Harmful?
Inorganic arsenic is a confirmed carcinogen and is the most significant chemical contaminant in drinking-water globally.
Arsenic can also occur in an organic form. Inorganic arsenic compounds (such as those found in water) are highly toxic while organic arsenic compounds (such as those found in seafood) are less harmful to health.
Arsenic poisoning occurs in multicellular life if quantities are larger than needed.
Arsenic contamination of groundwater is a problem that affects millions of people across the world. The United States Environmental Protection Agency states that all forms of arsenic are a serious risk to human health.
The immediate symptoms of acute arsenic poisoning include vomiting, abdominal pain, and diarrhea. These are followed by numbness and tingling of the extremities, muscle cramping, and death, in extreme cases.
Long-term exposure to inorganic arsenic, mainly through drinking-water and food, can lead to chronic arsenic poisoning. The first symptoms are usually observed in the skin and include pigmentation changes, skin lesions, and hard patches on the palms and soles of the feet (hyperkeratosis). These occur after a minimum exposure of approximately five years and can be a precursor to skin cancer.
In addition to skin cancer, exposure may also cause cancers of the bladder and lungs. Other adverse health effects that may be associated include developmental effects, diabetes, pulmonary disease, and cardiovascular disease. Arsenic-induced myocardial infarction, in particular, can be a significant cause of excess mortality.
The International Agency for Research on Cancer (IARC) has classified arsenic and arsenic compounds as carcinogenic to humans and has also stated that arsenic in drinking-water is carcinogenic to humans.
Arsenic is one of WHO’s 10 chemicals of major public health concern. WHO’s work to reduce arsenic exposure includes setting guideline values, reviewing evidence, and providing risk management recommendations. WHO publishes a guideline value for arsenic in its Guidelines for drinking-water quality. The Guidelines are intended for use as the basis for regulation and standard-setting worldwide.