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Arsenic
appears in three allotropic forms: yellow, black and grey; the stable
form is a silver-gray, brittle crystalline solid. It tarnishes rapidly
in air, and at high temperatures burns forming a white cloud of arsenic
trioxide. Arsenic is a member of group Va of the periodic table, which combines readily with many elements. |
Arsenic
is one of the most toxic elements that can be found. Despite their
toxic effect, inorganic arsenic bonds occur on earth naturally in small
amounts. Humans may be exposed to arsenic through food, water and air.
Exposure may also occur through skin contact with soil or water that
contains arsenic. Levels of arsenic in food are fairly low, as it is not added due to its toxicity. But levels of arsenic in fish and seafood may be high, because fish absorb arsenic from the water they live in. Luckily this is mainly the fairly harmless organic form of arsenic, but fish that contain significant amounts of inorganic arsenic may be a danger to human health. Arsenic exposure may be higher for people that work with arsenic, for people that live in houses that contain conserved wood of any kind and for those who live on farmlands where arsenic-containing pesticides have been applied in the past. Exposure to inorganic arsenic can cause various health effects, such as irritation of the stomach and intestines, decreased production of red and white blood cells, skin changes and lung irritation. It is suggested that the uptake of significant amounts of inorganic arsenic can intensify the chances of cancer development, especially the chances of development of skin cancer, lung cancer, liver cancer and lymphatic cancer. A very high exposure to inorganic arsenic can cause infertility and miscarriages with women, and it can cause skin disturbances, declined resistance to infections, heart disruptions and brain damage with both men and women. Finally, inorganic arsenic can damage DNA. A lethal dose of arsenic oxide is generally regarded as 100 mg. Organic arsenic can cause neither cancer, nor DNA damage. But exposure to high doses may cause certain effects to human health, such as nerve injury and stomachaches. |
Environmental effects of arsenic
The
arsenic cycle has broadened as a consequence of human interference and
due to this, large amounts of arsenic end up in the environment and in
living organisms. Arsenic is mainly emitted by the copper producing
industries, but also during lead and zinc
production and in agriculture. It cannot be destroyed once it has
entered the environment, so that the amounts that we add can spread and
cause health effects to humans and animals on many locations on earth. Plants absorb arsenic fairly easily, so that high-ranking concentrations may be present in food. The concentrations of the dangerous inorganic arsenics that are currently present in surface waters enhance the chances of alteration of genetic materials of fish. This is mainly caused by accumulation of arsenic in the bodies of plant-eating freshwater organisms. Birds eat the fish that already contain eminent amounts of arsenic and will die as a result of arsenic poisoning as the fish is decomposed in their bodies. |
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