Arsenic is a metalloid found in nature. It is among the most common element in the earth’s crust, combined with igneous and sedimentary rocks, particularly belonging to sulfidic minerals. It is a component of more than 245 minerals. Its components are not only found into rocks, the ground, the water and in the air but also in plant and animal tissues. Although elemental arsenic is not water-soluble, its salts have a wide range of solubility depending on the pH and the ionic environment. Arsenic can have different values of states : -3, 0, +3 e +5. The value of state +3 is the dominating form in reducing conditions , while the value of state +5 (arsenate) is generally the most stable form in oxidising environments.
Arsenic is commonly concentrated in mineral deposits together with sulphides and has a great affinity to pyrite, FeS2, one of the most common sulphides on the earth’ crust. It can also be found in hydrated iron oxides. Arsenic and its compounds are mobile in the environment. The arsenic sulphides (As2S3, As4S4, As4S3 As4S5) are turned into arsenic trioxide, As2O3, due to the rock aging action and enter the arsenic cicle as dust, or dissolved into rain, rivers or underground waters. Arsenic can also enter the food chain and be spread to plants and animals. Into the environment, the highest concentrations of arsenic are found in underground waters, where is highly mobile due to the pH values typically between 6,5-8,5. The concentrations of arsenic in underground waters are for most of the countries inferior to 10μg / L. The values in literature range from <0,5 to 5000 µg / L. The great part of the high levels of arsenic in underground waters are the result of natural events.
The presence of natural or anthropic arsenic in drinking water has been recognized as an important health problem in different regions in the world since the last two or three decades. In Bangladesh, India, Taiwan, China, Mexico, Argentina, Chile and United States have been identified areas with an high concentration of arsenic. Also in Europe there can be found polluted areas, such as the Danube region and central Italy.
Long-term exposition to arsenic from drinking water or food can cause skin cancer and skin injuries. Beyond skin cancer, long-term exposition to arsenic can cause bladder or lung cancer. The International Agency For Cancer Research (IARC) has classified arsenic compounds and arsenic in drinking water as human carcinogen. Other bad effects on health which can be associated to long-term ingestion of arsenic include effects on development, neurotoxicity, diabetes and cardiovascular diseases.
In 2010 the joint committee FAO / OMS for food additives (JECFA) has evaluated the effects of arsenic on human health on the basis of recent data and has concluded that, in some regions in the world, concentrations of inorganic arsenic in drinking water exceeding 50-100 μg / L proved to have adverse effects. In other areas, with concentrations of arsenic of 10-50 μg / L, JECFA has concluded that "even if there is the possibility of adverse effects, these are of low-impact and difficult to detect in epidemiological studies".
In any case, the maximum concentration acceptable (MAC) for arsenic in drinking was fixed by OMS at 0.010 mg / L (10 μg / L).
The emission of a guideline for drinking water has to take into account the capability of measuring the pollutants and removing it from water. Arsenic can be measured reliably at a concentration of 0,001 mg / L. It should be therefore removed in order to obtain a concentration inferior to OMS standard value of 0,010 mg / L.
Having said that, all European countries have adopted as a limit the value of 0,010 mg/L. With Gruppo Zilio Filter Materials not only you can reach this limit but also settle greatly under this threshold.