Chemical Fact Sheet
Arsenic
| Chemical Abstract Number (CAS #) | 7440-38-2 |
|---|---|
| Synonyms | ARSENIC-BLACK |
| ARSENIC-75 | |
| COLLOIDAL-ARSENIC | |
| Gray-arsenic | |
| Metallic-arsenic | |
| Analytical Methods | EPA, 200.7,200.8,200.9,206.2 |
| EPA 6010,7060 | |
| Molecular Formula | As |
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Synopsis
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(L. arsenicum, Gr. arsenikon, yellow orpiment, identified with arsenikos, male, from the belief that metals were different sexes; Arabic, Az-zernikh, the orpiment from Persian zerni-zar, gold), As; at. wt. 74.92159(2); at. no. 33; valence -3, 0, +3 or +5. Elemental arsenic occurs in two solid modifications: yellow, and gray or metallic, with specific gravities of 1.97, and 5.73, respectively. Gray arsenic, the ordinary stable form, has a m.p. of 817'C (28 atm) and sublimes at 614'C. Several other allotropic forms of arsenic are reported in the literature. It is believed that Albertus Magnus obtained the element in 1250 A.D. In 1649 Schroeder published two methods of preparing the element. It is found native, in the sulfides realgar and orpiment, as arsenides and sulfarsenides of heavy metals, as the oxide, and as arsenates. Mispickel, arsenopyrite, (FeSAs) is the most common mineral, from which on heating the arsenic sublimes leaving ferrous sulfide. The element is a steel gray, very brittle, crystalline, semimetallic solid; it tarnishes in air, and when heated is rapidly oxidized to arsenous oxide (AS2O3) with the odor of garlic. Arsenic and its compounds are poisonous. These values, however, are being studied, and may be lowered. Arsenic is also used in bronzing, pyrotechny, and for hardening and improving the sphericity of shot. The most important compounds are white arsenic (AS2O3), the sulfide, Paris green 3Cu(AsO2)2 - Cu(C2H3O2)2, Calcium arsenate, and lead arsenate; the last three have been used as agricultural insecticides and poisons. Marsh's test makes use of the formation and ready decomposition of arsine (AsH3). Arsenic is available in high-purity form. It is finding increasing uses as a doping agent in solid-state devices such as transistors. Gallium arsenide is used as a laser material to convert electricity directly into coherent light. Natural arsenic is made of one isotope 75 As. Twenty-five other radioactive isotopes and isomers are known. Arsenic (99%) costs about $175/kg. Purified arsenic (99.9995%) costs about $2/gm. |
| Use | ALLOYING CONSTITUENT MFR OF CERTAIN TYPES OF GLASS; IN METALLURGY FOR HARDENING COPPER, LEAD ALLOYS TO MAKE GALLIUM ARSENIDE FOR DIPOLES & OTHER ELECTRONIC DEVICES; DOPING AGENT IN GERMANIUM & SILICON SOLID STATE PRODUCTS; SPECIAL SOLDERS; MEDICINE COMPONENT OF ALLOYS; COMPONENT OF ELECTRICAL DEVICES MEDICATION: TO MFR ARSENICAL ORG CMPD FOR THERAPEUTIC USE (76)As radioactive tracer in toxicology. Used as a catalyst in the manufacture of ethylene oxide. Used in semiconductor devices. |
| Consumption Patterns | 90% AS AN ALLOYING ADDITIVE; 7% IN ELECTRONIC DEVICES (LEAD-BASE BATTERY GRIDS AND CABLE SHEATHING); 3% AS AN INTERMEDIATE FOR ARSENICALS USED IN VETERINARY MEDICINE (1971) The USA consumes about 37,500 tons/yr. Industrial chemicals (wood preservatives), 68%; agricultural chemicals (herbicides and dessicants), 23%; glass, 4%; nonferrous alloys, 3%; and other uses, 2% (1986) Approximately 10 tons of high-purity arsenic metal was used /in 1986/ in the electronics industry for the production of semiconductor materials. |
| Apparent Color | A SILVER-GREY BRITTLE, CRYSTALLINE, METALLIC-LOOKING SUBSTANCE ; IT EXISTS IN THREE ALLOTROPIC FORMS, THE YELLOW (ALPHA), BLACK (BETA) AND GREY (GAMMA) FORMS ; HEXAGONAL, RHOMBIC, GRAY, METALLIC |
| Odor | Odorless |
| Melting Point | 817 DEG C @ 28 ATM |
| Molecular Weight | 74.92 |
| Density | 5.727 @ 14 DEG C |
| Sensitivity Data | ARSENICAL DUSTS ARE IRRITATING TO UPPER RESP TRACT EYES. CONJUNCTIVITIS PRODUCED BY THESE SUBSTANCES ARE CHARACTERIZED BY ITCHING, BURNING, WATERING OF EYES. |
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Chemical and Physical Properties |
A yellow modification which has no metallic properties is obtained by sudden cooling of arsenic-vapor. This yellow arsenic is converted back to the gray modification upon very short exposure to ultraviolet light. VAPORIZATION BECOMES APPARENT AT 100 DEG C AND IS ALREADY RAPID AT 450 DEG C; BRINELL HARDNESS: 147; MOHS' SCALE: 3.5; HEAT OF SUBLIMATION: 30.5 KCAL/G-ATOM; 7.63 KCAL/G-ATOM; SPECIFIC HEAT: 0.0822 FOR 0 DEG C TO 100 DEG C; HEAT OF FUSION: 22.4 KCAL/G-ATOM; 6.620 KCAL/G-ATOM; NOT ATTACKED BY COLD SULFURIC ACID OR HYDROCHLORIC ACID; CONVERTED BY HNO3 OR HOT H2SO4 INTO ARSENOUS OR ARSENIC ACID; DIELECTRIC CONSTANT: 10.23 @ 20 DEG C & 60 CYCLES 613 deg C (sublimes) |
| Environmental Impact | EPA estimates that more than six million people living within 12 miles of major sources of copper, zinc, and lead smelters may be exposed to 10 times the average USA atmospheric levels of arsenic. The EPA says that 40,000 people living near some copper smelters may be exposed to 100 times the national atmospheric average. Arsenic and arsenic cmpd. Occupations with potential exposure: acetylene workers, acid dippers, alloy makers, aniline color makers, aniline workers, arsine workers, Babbit metal workers, bleaching powder markers, boiler operators, brass makers, bronze makers, bronzers, cadmium workers, cattle dip workers, ceramic enamel makers, ceramic makers, copper smelters, defoliant applicators and makers, dimethyl sulfate makers, drug makers, dye makers, electrolytic copper makers, electroplaters, enamelers, etchers, farmers, ferrosilicon workers, fertilizer makers, fireworks makers, galvanizers, glass makers, gold extractors, gold refiners, hair remover makers, herbicide makers, hide preservers, hydrochloric acid workers, illuminating gas workers, insecticide makers, jewelers, lead burners, lead shot makers, lead smelters, leather workers, lime burners, metal cleaners, metal refiners, nitrocellulose makers, ore smelter workers, organic chemical synthesizers, paint makers, painters, paper makers, petroleum refinery workers, pigment makers, plastic workers, plumbers, printing ink workers, rayon makers, rodenticide makers, semiconductor compound makers, sheep dip workers, silver refiners, soda makers, solderers, submarine workers, sulfuric acid workers, taxidermists, textile printers, tinners, tree sprayers, type metal workers, water weed controllers, weed sprayers, wood preservative makers, wood preservers, and zinc chloride makers, etc. High exposure to arsenic fumes and dust may occur in the smelting industries; the highest concn most likely occur among roaster workers. Nonworker populations living near point emission sources of arsenic to air may have increase in lung cancer. INDUSTRIAL AND AGRICULTURAL RISK. THE INDIVIDUALS AT GREATEST RISK ARE SMELTER WORKERS, ALTHOUGH THERE IS SOME SUGGESTION THAT WOMEN RESIDING NEAR SUCH OPERATIONS INCUR A GREATER INCIDENCE OF RESPIRATORY CANCER. Urinary arsenic levels of residents on a downwind transect from a smelter were measured. It was found that arsenic levels decreased with distance from the smelter. Levels were 0.3 ppm at a distance of 0-0.4 miles and 0.02 ppm at a distance of 2.0-2.4 miles. Samples of vacuum cleaner dust were also collected, and arsenic was reported to decline from 1,300 ppm at a distance of 0-0.4 miles to 70 ppm at a distance of 2.0-2.4 miles. This suggests that arsenic exposure was not confined to one section of the smelter, but extended also to the surrounding community. Thus, the "non-exposed" smelter workers might also have had a degree of arsenic exposure. The influence of physiological factors, personal habits, use of drugs, genetic disorders, acquired diseases, and pathological factors that can alter biological indicators used to assess industrial worker exposure were discussed. Physiological factors included diet, age, and sex. Consumption of crustaceans markedly increased arsenic levels in urinary arsenic. BODY: Normal values of arsenic in urine vary from 0.013 to 0.046 mg/l, to 0.13, to 0.25. The urinary excretion in mg/l, of elements that are freely eliminated by this route, such as fluroine, mercury, and arsenic, is at most 2.5 to 5 times the occupational exposure in mg/cu m of air. Colostrum and transitional milk were obtained from 15 healthy mothers living in the Athens area /Greece/ with mean age of 26 yr. Mature milk was obtained from 5 of the 15 mothers. The concn of arsenic and some other trace metals in human milk were determined using neutron activation analysis. There were no differences between levels in human colostrum, transitional, and mature milk, all of which were about 3 ug/l (range 0.6-6.3 ug/l). HUMAN BODY BURDEN LESS THAN 100 MG/70 KG. |
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Environmental Fate |
Arsenic is found widely in nature and most abundantly in sulfide ores. Arsenopyrite (FeAsS) is the most abundant one. ARSENIC ... ACCOUNTS FOR 5X10-4% OF THE EARTH'S CRUST. MINERALS CONTAINING ARSENIC INCLUDE: ... ORPIMENT ... REALGAR ... CLAUDETITE ... COBALTITE ... ENARGITE ... .Ceramic artists can be exposed to many hazardous materials, generally related to dry clays, glazes and kiln use. Glazes can contain lead, antimony, arsenic, barium, beryllium, boron, chromium, cobalt, cadmium, copper, vanadium and other materials.Aquatic Fate: Arsenic as a free element (0-oxidation state) is rarely encountered in natural waters. Soluble inorganic arsenate (+5-oxidation state) predominates under normal conditions since it is thermodynamically more stable in water than arsenite (+3 oxidation state).Hair samples collected from common hare (Lepus europaeus), common vole (Microtus arvallis), and wood mouse (Apodemus sylvaticus) were subjected to instrumental neutron activation analysis (INAA). Up to 18 elements (arsenic, gold, bromine, cesium, cobalt, chromiuum, copper, iron, mercury, potassium, lanthanium, sodium, antimony, scandium, selenium, samarium, thorium and zinc) were detected in each hair sample. Animal hair samples from areas polluted by thermal power plants burning coal were taken and compared with hair samples from the animals living in relatively nonpolluted control areas. Animal hair samples from areas with higher levels of pollution contain usually higher concn of toxic and essential elements as As, Co, Cr, Fe, and Se. Muride rodents can be used for more detailed monitoring of environmental exposure than the hare. Moreover, the hair of the common vole shows usually highest levels of contamination as compared with the wood mouse, which could be explained by different components of feed. Animal hair was a rather sensitive indicator of environmental exposure and INAA proved to be a suitable analytical tool for this purpose.Present, background, and anthropogenic loading rates of copper, nickel, zinc, lead, cadmium, chromium, mercury, arsenic, and selenium to lake sediments were calculated, and compared to concentrations in several fishes. ... The majority of lakes had anthropogenic loadings of zinc, cadmium, mercury, and arsenic, which were presently 1.8-2.6 times background loadings. ... Enrichment by zinc, cadmium, arsenic, and especially lead was greater closer to industrialized regions. Anthropogenic and precipitation loadings for zinc, lead, cadmium, and arsenic were similiar, suggesting that anthropogenic inputs are atmospheric and that current atmospheric loadings are mostly anthropogenic. ... Pilot plant tests of two treatment methods activated alumina and ion exchange for removing arsenic from drinking water were evaluated at the Fallon, Nevada (USA), Naval Air Station. The arsenic concentration was 0.080-0.116 mg/l, exceeding the 0.05-mg/l maximum contaminant level. Although the valence of arsenic was not determined, the prechlorination process and test results suggest it was probably arsenic V. Chlorinated drinking water from the Naval Air Station was used for evaluating the efficacy of the activated alumina and ion exchange systems. The major water quality factors affecting the removal of arsenic by these methods were: pH of feedwater, arsenic concentration, sulfate concentration, and alkalinity. The major operational factors affecting removal were: flow rate, down time, and media clogging. Capital and operating costs for arsenic removal are estimated for the activated alumina method at optimum pH (5.5) for each of the three small community systems drawing water from the same aquifer.Colostrum and transitional milk were obtained from 15 healthy mothers living in the Athens area /Greece/ with mean age of 26 yr. Mature milk was obtained from 5 of the 15 mothers. The concn of arsenic and some other trace metals in human milk were determined using neutron activation analysis. There were no differences between levels in human colostrum, transitional, and mature milk, all of which were about 3 ug/l (range 0.6-6.3 ug/l). /Inorganic arsenic/ LIVERS OF FISH FROM THE GREAT LAKES CONTAIN 5.6 TO 80 PPB MAINLY IN THE FAT FRACTION. FISH GENERALLY CONTAIN LOWER ARSENIC LEVELS THAN OTHER AQUATIC ORGANISMS. Arsenic levels in fish muscle from Abu Quir Bay ranged from 0.97 to 10.5 ppm. Levels in Tilapia muscle from Idku and Margut Lakes ranged from 0.11 to 0.18 ppm. Arsenic levels in fish livers were not consistantly higher than in fish muscle. The arsenic content of edible muscle of 2 tuna species (Thunnus thynnus and Thunnus toggel) caught in Arabian Sea waters was 2.88 and 2.51 ug/g dry wt, resp, for the 2 species. A marked increase in arsenic content was found with increasing wt of the 2 fish species. |
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Drinking Water Impact |
Present, background, and anthropogenic loading rates of copper, nickel, zinc, lead, cadmium, chromium, mercury, arsenic, and selenium to lake sediments were calculated, and compared to concentrations in several fishes. The majority of lakes had anthropogenic loadings of zinc, cadmium, mercury, and arsenic, which were presently 1.8-2.6 times background loadings. .Enrichment by zinc, cadmium, arsenic, and especially lead was greater closer to industrialized regions. Anthropogenic and precipitation loadings for zinc, lead, cadmium, and arsenic were similiar, suggesting that anthropogenic inputs are atmospheric and that current atmospheric loadings are mostly anthropogenic. Pilot plant tests of two treatment methods activated alumina and ion exchange for removing arsenic from drinking water were evaluated at the Fallon, Nevada (USA), Naval Air Station. The arsenic concentration was 0.080-0.116 mg/l, exceeding the 0.05-mg/l maximum contaminant level. Although the valence of arsenic was not determined, the prechlorination process and test results suggest it was probably arsenic V. Chlorinated drinking water from the Naval Air Station was used for evaluating the efficacy of the activated alumina and ion exchange systems. The major water quality factors affecting the removal of arsenic by these methods were: pH of feedwater, arsenic concentration, sulfate concentration, and alkalinity. The major operational factors affecting removal were: flow rate, down time, and media clogging. Capital and operating costs for arsenic removal are estimated for the activated alumina method at optimum pH (5.5) for each of the three small community systems drawing water from the same aquifer. |
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Disposal |
At the time of review, criteria for land treatment or burial (sanitary landfill) disposal practices are subject to significant revision. Prior to implementing land disposal of waste residue (including waste sludge), consult with environmental regulatory agencies for guidance on acceptable disposal practices. Arsenic elemental arsenic wastes should be placed in long term storage or returned to suppliers or manufacturers for reprocessing. Arsenic bearing sludges from the purification process in the production of antimony oxide are poor candidates for incineration. An analysis of the health hazards associated with the operation of municipal sludge incinerators was done on the multiple hearth incinerator design, which comprises approximately 80 percent of the total number of sludge incinerators in the USA. Parameters discussed included sludge contaminant concentration, source characteristics, emission rate estimates, dispersion parameters, and health risk values. Estimates of environmental contamination by cadmium, chromium, copper, nickel, lead, and zinc due to emission loss from the incinerator were calculated. In addition, the human cancer risk (calculated as the effect index) associated with inhalation of incinerator emissions was calculated. The index values were greater than unity for arsenic, beryllium, cadmium, chromium, mercury, nickel, and lead. |
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Atmosphere |
Total arsenic in rural USA over 1 yr ranged from 0.0 to 0.1 ug/cu m; total As in rural Michigan over 1 yr was 0.0046 ug/cu m; total As in suspended particulate matter in Yellowknife NWT Northwest Territory over 1 yr ranged from <0.01 to 0.01 ug/cu m. |
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