Arsenic (whose chemical symbol is As) is a natural component of the earth's surface (Earth's crust). It can occur both in inorganic form (as a chemical element or as some arsenic salts) and in organic form, in compounds that are generally less toxic than inorganic arsenic.
In nature, its presence is found in rocks, soil, air and both underground and surface water. In some territories, arsenic concentrations can be high for purely natural causes and independent of the pollution caused by human productive activities which can, however, further increase the levels.
Arsenic compounds are used in the microelectronics industry, semiconductor manufacturing, dye production, the textile industry, paper manufacturing and glass processing.
At one time, inorganic arsenic compounds were widely used in the treatment and preservation of wood, while organic arsenic compounds were used in agriculture: both of these uses have now been greatly reduced.
In the medical field, up to the 1940s, inorganic arsenic was used in the treatment of certain pathologies such as: leukemia, psoriasis, chronic bronchial asthma; only recently, in America, the Food and Drug Administration , FDA) has authorized its use for the treatment of some specific forms of leukemia.Sources of exposure
Sources of exposure
The exposure (by ingestion, inhalation or skin contact) of the population with arsenic occurs mainly through:
- food: fish, crustaceans and molluscs are the foods that generally contain higher levels of arsenic absorbed by the water they live in. Fortunately, however, it is arsenic mainly present in organic and therefore non-toxic form. The group of foods that according to estimates of the European Food Safety Authority (EFSA) contributes most to the exposure to inorganic arsenic are cereals and cereal products. These foods, such as bread and pasta, usually contain little arsenic, but they are widely consumed products that therefore have a great impact on the intake. Rice is a cereal that may contain a lot of inorganic arsenic, but is on average less consumed in Europe
- water: the water in the areas of volcanic origin is rich in arsenic, the arsenic is present in it in an inorganic form and the contact can take place in:
- direct, through drinking water
- indirect, through the use of water used for the preparation of food and for the irrigation of cultivated fields with consequent contamination of plant foods, especially cereals
- tobacco smoke, both that inhaled and aspirated by a smoker (active smoke) and that breathed in an involuntary way (passive smoke). This is due to the ability of the tobacco plant to efficiently absorb, through its roots, metals such as inorganic arsenic present in the soil
- professional exhibitions, during industrial production processes where you work with arsenic (for example, in foundries there are fumes containing arsenic, which can be breathed in if safety regulations are not respected)
This chemical element, moreover, can be present in the atmosphere as a result of the activity and emissions of volcanoes or even for the decomposition of the minerals that contain it. In any case, exposure to arsenic through the air is generally very low and considered lower than those listed above.Effects on health
Effects on health
There are two types of arsenic in nature: organic and inorganic. Inorganic forms (such as those that contaminate water) are toxic, unlike organic forms (such as those that contaminate fish and crustaceans) which are much less so.
The inorganic forms, once ingested or inhaled, are well absorbed by the organism, which in any case manages to transform them into organic compounds, which are then easily eliminated in the urine. differs from individual to individual, mainly on the basis of personal genetic characteristics. For this reason, exposure to the same amount of arsenic can have very variable health effects depending on the person.Organic compounds are generally poorly absorbable and easily eliminated with feces and urine.
Taking a high dose of arsenic (about 10-50 milligrams) causes acute poisoning characterized by the following disorders (symptoms):
- He retched
- abdominal pain
- numbness in the limbs
- muscle cramps and twitching due to inflammation of many peripheral nerves (polyneuritis) which, at higher doses of arsenic, can lead to blockage of the heart and respiratory muscles and death
The ingested dose potentially capable of causing the death of an adult weighing approximately 60 kg is approximately 120 mg (1-2 mg / kg body weight).
Following repeated exposure over time to low doses of arsenic, the following may occur:
- changes in skin pigmentation (color)
- thickening of the skin on the palm of the hand and sole of the footdue to excessive presence of a skin protein called keratin (hyperkeratosis)
- skin lesions
These disorders (symptoms) usually appear after about 5 years of exposure to arsenic and can lead to the formation of skin tumors.
Additional effects caused by arsenic may include: the onset of diabetes, cardiovascular disease (including myocardial infarction) and changes in the development of the fetus during pregnancy (inorganic arsenic can pass the placenta).
In addition to skin cancers, in populations exposed to arsenic for prolonged times, an increased risk of onset of diseases such as lung cancer and bladder cancer has been observed.
The International Agency for Research on Cancer (IARC) has classified arsenic in group 1 (human carcinogens), that is, among those substances with a high degree of probability of causing cancer in humans.
According to the World Health Organization (WHO), the consumption of drinking water containing arsenic in quantities between 0.05 and 0.1 milligrams per liter of drinking water (corresponding to 50-100 micrograms per liter) increases the risk of developing a cancer of the skin, lung or bladder. Therefore the maximum concentration of arsenic in drinking water has been set at 10 μg / L by the WHO and by Directive 98/83 / EC since it is believed that higher arsenic levels may lead to health risks strictly dependent on the duration of exposure and the nutritional status of the exposed population. These values aim to ensure that water intended for human consumption can be safely consumed throughout the life span.
When arsenic levels are lower, the number of new cancer cases (incidence) has never been found to be different from that of populations living in areas not exposed to arsenic.Prevention and control
Prevention and control
Limiting the exposure of people to inorganic arsenic as much as possible can be considered the most important preventive action for the general population and for workers. In addition to the workplace, therefore, the control must be essentially aimed at analyzing the quality of water intended for human consumption and that used for irrigation of fields cultivated with agricultural products.
In our country, the level of arsenic presence in drinking water is a regularly controlled value.
The World Health Organization (WHO) recommends a limit value for the presence of arsenic in drinking water equal to 0.01 milligrams (equal to 10 micrograms, μg) per liter of water; it also points out that, depending on the region considered and of the specific characteristics of the territory, even higher levels can be indicated and temporarily accepted (considering that an increased risk for tumors has been highlighted for arsenic concentrations higher than 50 μg / L).
When the arsenic content present in the water is determined by the very nature of the territory and the rocks, it is necessary that the suppliers of water intended for human consumption intervene to remove or, at least, lower these levels of arsenic, replacing the supply source. water, mixing with other water with a low arsenic content (dilution effect), installing efficient removal systems in water purification plants. By law, even the producers of bottled water are obliged to respect the concentration limit of 10 μg / L of arsenic, but there is no obligation to indicate the real values measured on the label.
Regarding diet, the European Food Safety Authority (EFSA) has identified a range of daily doses (from 0.3 to 8 micrograms per day per kilogram of body weight) that would lead to an increase in risk. 1% of having lung cancers, bladder cancers and skin cancers.Therapy
In case of ingestion of arsenic, the treatment (therapy) to combat acute poisoning is based on subjecting the person to gastric lavage or in "carrying out a specific pharmacological therapy (chelation therapy) with the administration of substances capable of forming" complexes "with arsenic which are subsequently eliminated in the urine. The chelating substances are administered through injections (intravenously or intramuscularly).
In cases of intoxication due to repeated and prolonged (chronic) exposure, drugs (for example, penicillamine-D) are used by mouth and specific therapies are applied for the resulting diseases.Bibliography
Encyclopedia Treccani. Arsenic
World Health Organization (WHO) Media center. Arsenic (English)
US Environmental Protection Agency (EPA). EPA Fact Sheet on Arsenic (English)In-depth link
ISPESL information booklet. Arsenic: contamination and environmental exposure
European Food Safety Authority (EFSA). Dietary exposure to inorganic arsenic in the European population.EFSA Journal. 2014; 12
European Food Safety Authority (EFSA). Scientific opinion on arsenic in food. EFSA Journal. 2009; 7