Arsenic is present in nature in the form of sulfates. Its content in lead-zinc concentrates is about 1%. Due to volatility, it easily enters the atmosphere.
The strongest sources of contamination with this metal are herbicides (chemicals to control weeds), fungicides (substances to combat plant fungi) and insecticides (substances for controlling harmful insects).
On the toxic properties of arsenic refers to accumulating poisons. By the degree of toxicity, one should distinguish between elementary arsenic and its compounds. Elementary arsenic is relatively less toxic, but has teratogenic properties. Harmful effects on hereditary material (mutagenicity) are contested.
Arsenic compounds are slowly absorbed through the skin, quickly absorbed through the lungs and the gastrointestinal tract. The lethal dose for humans is 0.15-0.3 g.
Chronic poisoning causes nerve diseases, weakness, numbness of the extremities, itching, darkening of the skin, bone marrow atrophy, changes in the liver. Arsenic compounds are carcinogenic to humans. Arsenic and its compounds belong to the II class of danger.
As a result of widespread distribution in the environment and use in agriculture, arsenic is present in most food products. Usually its content in foods is small enough – less than 0.5 mg / kg and rarely exceeds 1 mg / kg, with the exception of some marine organisms that accumulate this element. In the absence of significant contamination, the arsenic content in bread products is up to 2.4 mg / kg, fruits up to 0.17 mg / kg, drinks up to 1.3 mg / kg, meat up to 1.4 mg / kg, dairy products up to 0 , 23 mg / kg. Marine products contain more arsenic, usually at the level of 1.5 … 15.3 mg / kg.
Arsenic is present in almost all fresh water. However, in drinking water from various sources, the levels of arsenic are determined by the nature of the rocks lying. In some geological formations, arsenopyrite is deposited, which is
Source of arsenic in fresh water and leads to an increase in its concentration to 0.5 … 1.3 mg / l. Regular use of such waters in the household can lead to an excessive intake of arsenic into the body and cause symptoms of chronic arsenic poisoning. For example, in Argentina, chronic regional arsenic poisoning caused by the consumption of water containing 1 to 4 mg / l of As203 was observed. A similar situation was observed in Antofagasta (Chile). The use of well water containing 0.6 mg / L arsenic led to local chronic poisoning in Taiwan.
Industrial, as well as accidental pollution can lead to a significant increase in the natural level of arsenic in food and beverages. For example, in Baltimore, a territory was discovered where the death rate from cancer is 4.5 times higher than in the city as a whole. This strip surrounds the former factory, which produced arsenic for 100 years. More tragic case occurred in Japan in 1955, when more than 12,000 children were poisoned. They were fed a milk formula, which consisted of powdered milk contaminated with arsenic oxide (III). He accidentally got into sodium phosphate, which was stabilized with milk powder. Sodium phosphate was a waste in the separation of aluminum from bauxite, in which it contained a substantial amount of arsenic. More than 120 children died from consumption of the mixture after 33 days with a daily dose of As2O3 – 3.5 mg.
The use of arsenic compounds in vineyards as pesticides has led to cases of wine poisoning.
Arsenic can cause both acute and chronic poisonings. Acute are well known to forensic forensics. A number of examples are known. One of them – the case of Marie Madeleine de Branvilliers (1630-1676 biennium). Marie Madeleine was born in a wealthy noble family and from adolescence shone with beauty. In order to acquire a huge inheritance, which she was deprived of due to obscene behavior, Marie Madeleine pours arsenic into the food of her father and two brothers. The Supreme Court of the Parisian Parliament found her guilty of intentional murders, and the plow accepted her beautiful head. There is also a version of the poisoning of arsenic by Napoleon Bonaparte. With the help of neutron activation analysis of Napoleon’s hair from different periods of his life, experts established that the arsenic content in them is 13 times higher than the normal norm for human hair, and the arsenic deposition in growing hair coincided in time with the period of Napoleon’s stay on St. Helena.
Arsenic binds to sulfhydryl groups of proteins and thus inhibits the action of many enzymes involved in the processes of cellular metabolism of aspiration.
Chronic arsenic poisoning leads to loss of appetite and weight loss, gastrointestinal disorders, peripheral neuroses, conjunctivitis, hyperkeratosis and skin melanoma. Melanoma occurs with prolonged exposure to arsenic and can lead to the development of skin cancer.
Experts of FAO and WHO established an allowable daily dose of arsenic 0.05 mg / kg of body weight, which for an adult is about 3 mg / day.