Arsenic

Classification:

Arsenic is a chemical element. It is rarely mined in its metallic form. Normally, arsenic exists as an oxide or sulfide mineral, but it is also found in Pb-, Cu-, Auand Sn-ores as trace element; for further details see under the heading belovite.

Cas:

7440-38-2, 8028-73-7

Synonyms/Trade Names:

Arsen, Arsenic Black, Arsenic-75, Hüttenrauch, Scherbenkobalt; Arsenism.

Chemistry/Composition:

As. When found as a plain mineral, it can contain Bi <10% .

Structure:

Its structure is a distorted almost cubic packing.

Crystallographic Constants:

3.52 3.52 3.52 90.000 90.000 90.000.

Crystal Group:

Trigonal.

Color:

Black, uniformly.

Optical Properties:

Opaque.

Pleochroism:

None.

Powder Diagram:

3.52 2.77 2.05 2.88.

Natural Sources:

Mined in Australia (Wiluna), C a nada ( C o b alt) , Chile ( E l I n dio), Slov. Rep./Tsch. Rep. (Pribram), France (Salsigne), Germany (Wittichen/ Black Forest), Mexico (Mapimi, Zimapane), Namibia (Tsumed), Sweden (Boliden), Russia (Nertschinsk, Saprokovskoje/ Ural), and the USA (Sterling Hill, Butte).

Medical Importance:

Key Hazards:

Acute intoxication, carcinogenic.

Involved Organs:

Lung, skin, gastrointestinal tract.

Exposure/Epidemiology:

Exposure can occur during mining. Technically, it is mainly used in manufacturing pesticides, pigments, glass, alloys, and silicon microchips. Smelting of other metals may also cause an exposure to As. World production of As was 52×103 t in 1966.

Thresholds:

TWA STEL
mg/m3 mg/m3
Australia 0.05
Belgium
Czechoslovakia 0.6
Denmark 0.05
Finland 0.01
Germany (TRK) 0.1
Great Britain 0.2
Russia 0.01 0.04
Hungary 0.05
Poland 0.3
Sweden 0.03
United States: ACGIH 0.2
Germany: EKA: As in air As in urine
µg/m3 µg/l
10 50
20 80
50 175
100 330
200 640

Etiology/Pathophysiology:

About 80% of the inhaled arsenic is absorbed within the lungs. It can also be absorbed by the skin or gastrointestinal tract. Inorganic arsenic does not cross the bloodbrain barrier; however, it does cross the placenta. Arsenic reacts with sulfhydryl groups. It is stored in the hairs, skin, liver, kidney, spleen, bone narrow, and nails. Arsenic gas interferes with hemoglobin, and induces hemolysis (anaemia, hemoglobinuria) and acute renal failure. It is excreted up to 95% in the urine and only about 5% in the faeces. Chronic inhalation may induce lung cancer (3.3 times the normal risk). In its non-metallic form it is not toxic and only weakly water-soluble. The reported lethal dosage varies between 130-300 mg. Arsenic intoxication can be recognized by analysis of its content as follows:
Urine Arsenic normally < 5 µg/d Hairs normally < 2 µg/g Liver, Kidney normally <10 µg/100g Blood normally < 2 µg/100ml.

Lung Diseases:

Arsenic -especially As2O3 or AsCl3causes acute tracheobronchitis. Chronic inhalation is associated with an increased risk of lung cancer.

Clinical Presentation:

Chronic inhalation of arsenic fumes usually does not induce symptoms, although allergic skin reactions have been described.

Radiology:

Chest radiographs are usually normal.

Lung Function:

Usually normal.

Bronchoalveolar Lavage:

The lavage fluid can contain an increased number of dust-laden macrophages.

Pathology:

Gross:

The lungs display no abnormal findings.

Histology:

Arsenic is deposited in the distant airways, and ingested by macrophages. An increased number of intra-alveolar dust-laden macrophages and mild mononuclear inflammatory infiltrates may be noted. Acute intoxications present with hyperplasia and dysplasia of the pneumocytes. All cell types of the bronchial carcinoma can occur after exposure to arsenic fumes.

Prognosis:

Usually good, except for the increased risk of lung cancer.

Additional Diseases:

Acute Intoxication:

Anemia, nausea, vomiting, diarrhea, abdominal pain, cyanosis, hypotension, delirium, and death can occur within a few hours after uptake of large amounts of arsenic oxide.

Chronic intoxication:

Erythroderma, hyperkeratosis, hyperpigmentation, dermatitis, laryngitis, tracheitis, polyneuritis and disruption of mucus membranes may start to develop two hours after intoxication. Melanosis, carcinoma and basalioma of the skin have been described after chronic exposure.

Skin

: Arsenic warts (or: arsenic pocks) and hyperpigmentation are associated with chronic exposure to arsenic.

Remarks:

Epidemiological studies of workers employed in foundries of other metals like copper revealed an increased risk of lung cancer, which was attributed to the arsenic fumes in these factories.

References:

search Pubmed for Arsenic


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