------- AIR POLLUTION ASPECTS OF SELENIUM AND ITS COMPOUNDS Prepared for the National Air Pollution Control Administration Consumer Protection & Environmental Health Service Department of Health, Education, and Welfare (Contract No. PH-22-68-25) Compiled by Quade R. Stahl, Ph.D, Litton Systems, Inc. Environmental Systems Division 7300 Pearl Street Bethesda, Maryland 20014 September 1969 ------- FOREWORD As the concern for air quality grows, so does the con- cern over the less ubiquitous but potentially harmful contami- nants that are in our atmosphere. Thirty such pollutants have been identified, and available information has been summarized in a series of reports describing their sources, distribution, effects, and control technology for their abatement. A total of 27 reports have been prepared covering the 30 pollutants. These reports were developed under contract for the National Air Pollution Control Administration (NAPCA) by Litton Systems, Inc. The complete listing is as follows: Aeroallergens (pollens) Ethylene Aldehydes (includes acrolein Hydrochloric Acid and formaldehyde) Hydrogen Sulfide Ammonia Iron and Its Compounds Arsenic and Its Compounds Manganese and Its Compounds Asbestos Mercury and Its Compounds Barium and Its Compounds Nickel and Its Compounds Beryllium and Its Compounds Odorous Compounds Biological Aerosols Organic Carcinogens (microorganisms) Pesticides Boron and Its Compounds Phosphorus and Its Compounds Cadmium and Its Compounds Radioactive Substances Chlorine Gas Selenium and Its Compounds Chromium and Its Compounds Vanadium and Its Compounds (includes chromic acid) Zinc and Its Compounds These reports represent current state-of-the-art literature reviews supplemented by discussions with selected knowledgeable individuals both within and outside the Federal Government. They do not however presume to be a synthesis of available information but rather a summary without an attempt to interpret or reconcile conflicting data. The reports are ------- necessarily limited in their discussion of health effects for some pollutants to descriptions of occupational health expo- sures and animal laboratory studies since only a few epidemio- logic studies were available. Initially these reports were generally intended as internal documents within NAPCA to provide a basis for sound decision-making on program guidance for future research activities and to allow ranking of future activities relating to the development of criteria and control technology docu- ments. However, it is apparent that these reports may also be of significant value to many others in air pollution control, such as State or local air pollution control officials, as a library of information on which to base informed decisions on pollutants to be controlled in their geographic areas. Addi- tionally, these reports may stimulate scientific investigators to pursue research in needed areas. They also provide for the interested citizen readily available information about a given pollutant. Therefore, they are being given wide distribution with the assumption that they will be used with full knowledge of their value and limitations. This series of reports was compiled and prepared by the Litton personnel listed below: Ralph J. Sullivan Quade R. Stahl, Ph.D. Norman L. Durocher Yanis C. Athanassiadis Sydney Miner Harold Finkelstein, Ph.D. Douglas A. Olsen, Ph0D. James L. Haynes ------- The NAPCA project officer for the contract was Ronald C. Campbell, assisted by Dr. Emanuel Landau and Gerald Chapman. Appreciation is expressed to the many individuals both outside and within NAPCA who provided information and reviewed draft copies of these reports. Appreciation is also expressed to the NAPCA Office of Technical Information and Publications for their support in providing a significant portion of the technical literature. ------- ABSTRACT Selenium compounds in the atmosphere are known to cause irritation of the eyes, nose, throat, and respiratory tract in humans, and und.er conditions of prolonged, exposure, gastroin- testinal disorders result. In animals there are indications that selenium ingestion may cause cancer of the liver, and it is known to prod.uce pneumonia and. degeneration of liver and kidneys. Sources of atmospheric selenium includ.e combustion of industrial and. residential fuels, refinery waste gases and. fumes, and incineration of wastes including paper products which contain as much as 6 ppm selenium. Little data is available on concen- trations of selenium in the air; one report indicated an average value of 0.001 |ag/m3 in the vicinity of Boston, Mass. Electrostatic precipitators and. water scrubbers are effec- tive in controlling emissions of selenium in industrial opera- tions. No information has been found, on the economic costs of selenium air pollution, or on the costs of its abatement. Method.s are available for the analysis of selenium in the atmo- sphere. ------- CONTENTS FOREWORD ABSTRACT 1. INTRODUCTION 1 2. EFFECTS 2 2.1 Effects on Humans 2 2.1.1 Chronic Effects 2 2.1.2 Acute Poisoning 4 2.1.3 Retention and Elimination 5 2.1.4 Detoxification 7 2.1.5 Selenium in Nutrition 8 2.1.6 Elemental Selenium . 8 2.1.7 Selenium Dioxide, Selenites, Selenates . 9 2.1.8 Hydrogen Selenide 10 2.1.9 Selenium Oxychloride 11 2.1.10 Organoselenium Compounds 11 2.2 Effects on Animals 12 2.2.1 Livestock 12 2.2.2 Experimental Animals 15 2.2.2.1 Selenium, Selenites, Selenates. 15 2.2.2.2 Hydrogen Selenide 16 2.2.2.3 Organoselenium Compounds ... 18 2.2.3 Carcinogenesis 18 2.3 Effects on Plants 21 2.3.1 Selenium Indicator Plants 21 2.3.2 Secondary Selenium Absorbers 23 2.3.3 Grains, Vegetables, Grasses, and Other Vegetation 25 2.4 Effects on Materials 27 2.5 Environmental Air Standards 27 3. SOURCES 28 3.1 Natural Occurrence 28 3.2 Production Sources 30 3.3 Product Sources 32 3.4 Other Sources 35 3.5 Environmental Air Concentrations 37 ------- 4. ABATEMENT 42 5. ECONOMICS - 44 6. METHODS OF ANALYSIS 45 6.1 Sampling Methods 45 6.2 Qualitative Determination Methods 46 6.3 Quantitative Determination Methods 47 7. SUMMARY AND CONCLUSIONS 49 REFERENCES APPENDIX ------- LIST OF FIGURES 1. Selenium Content of Plants in Certain Counties in the United States 22 2. Distribution of Seleniferous Vegetation 24 ------- LIST OF TABLES 1. Symptoms and Gross Pathology of Chronic Selenium Poisoning in Livestock 14 2. Minimum Doses Fatal to Rats of Compounds of Selenium, Tellurium, Arsenic, Vanadium, and Molybdenum 17 3. Selenium Content of Coals 37 4. Atmospheric Selenium (1964-65) 38 5. Selenium Content of Particulates in Ambient Air, 1965 40 6. Mortality of Guinea Pigs from Inhalation of Hydrogen Selenide 63 7. Producers of Selenium in the United States (1967) . 64 8. Salient Selenium Statistics, 1965-67 65 9. List of Merchandisers and Consumers of Selenium and Its Compounds 66 10. Properties, Toxicity, and Uses of Some Selenium Compounds 69 11. Selenium Content of Dust from Air-Conditioning Filters, 1941 78 ------- 1. INTRODUCTION Selenium poisoning of humans and animals from ingestion of foods containing toxic amounts of selenium has been and still is a problem of great concern in the United States. Many plants used as food by humans and animals can accumulate high concen- trations of selenium from the soil. The soils of the Midwest are particularly high in selenium. Extensive studies have been made of the people, animals, food prod.ucts, and soils of the high seleniferous areas. Selenium has also been found to be an essential nutrient for animals and may be necessary for humans. Selenium compounds, although toxic, have seldom present- ed a serious problem in ind.ustry. Inhalation of the dust, fumes, or vapors of selenium compounds can irritate the eyes, nose, and throat, causing lacrimation, palpebral ed.ema, conjunctivitis, sneezing, nasal congestion, anosmia, and coughing. A study made in Boston, Mass, showed that there was ap- proximately 0.001 |_ig/m3 of selenium in samples of rain, snow, and air analyzed.. The sources of atmospheric selenium are be- lieved to be terrestrial, such as fuels and. ores used by indus- try, or possibly the burning of trash, particularly paper. ------- 2 . EFFECTS 2.1 Effects on Humans Little information is available on the toxicity of sele- nium through inhalation by humans. This is partly due to the infrequent occurrence of serious intoxication during the indus- trial use of selenium and its compound.s, and. also to the fact that human exposure is largely through the consumption of food. Ind.ustrial exposures are commonly a result of inhalation of the dust, fumes, and vapors of selenium and its compounds, although ingestion and skin contact are also important. The effects of ind.us trial exposure have been reported, by Hamilton, 51 > 52 Dud.ley,26'27 Amor and Pringle,2 Clinton,16 and Glover.44 Dis- cussion of these effects can be found in Trelease and. Beath, 119 Cerwenka and Cooper,12 Patty,89 and Cooper.19 The effects of selenium and. its compound.s on humans ap- pear to differ somewhat from those observed in animals. Thus, although animals can d,isplay d.efinite d.isease responses to the amount of selenium ingested, (see Section 2.2), there have been no chronic diseases in man attributable to selenium or its com- pound.s .4 2.1.1 Chronic Effects In general, chronic selenium intoxication in man prod.uces the following symptoms: depression, marked, pallor, coated, tongue, ------- languor, nervousness, occasional dermatitis, gastrointestinal disturbances, gid.d.iness, and. garlic od.or of the breath and. sweat .12,19,51 Moxon and Rhian°^ also noted, small local hemor- rhages, severe ascites, liver and splenic d.amage, emaciation, apathy, and progressive anemia. Hamilton^ mentioned irritation of nose, throat, and bronchi; pain in the lumbar region; nasal inflammation resembling that accompanying a cold; and night sweats. The above authors believe that garlic odor of the breath is one of the earliest and most characteristic symptoms of selenium intoxication. '43 Although there has been some question whether trace impurities of tellurium may give the gar- lic odor,89 this odor has been found in workers exposed to 99.999 percent pure selenium.^4 other authors believe that symptoms of respiratory ailments and. gastrointestinal disturbances are of ma- jor significance in the diagnosis of selenium poisoning. Rosenfeld. and. Beath^ stated, that the possible long-term effects of selenium may be kidney and. liver d.amage. Also fibro- sis of the lung may d.evelop following continued, exposure to dust and gases in the air. The studies of Had.jimarkos^ and. the data from earlier investigatorslO^/HI suggest that selenium can increase the sus- ceptibility of humans to d.ental caries. However, Cad.ell and CousinsH founcg no changes in primary, d.ecayed, missing, and ------- 4 filled teeth that would ind.icate dependence on selenium intake. Apparently the toxicity of selenium to humans may be somewhat dependent on certain physical characteristics. Dudley noted that mature men of dark complexion and stocky build had less tendency to develop the symptoms of selenium poisoning than did younger men with smaller build, and fair complexion. Wands-^a indicated that this effect might more reasonably be d.ue to dietary habits of ethnic or nationality groups, such as the high level of wheat protein in Italian diets. Besides the more obvious irritation effects of selenium and its compound.s, it appears that some toxic action results from the blocking of several enzyme systems. ' 2.1.2 Acute Poisoning The intense irritation prod.uced by d.usts and. fumes of se- lenium and. its compounds normally prevents excessive exposure to high concentrations of selenium, and. hence acute poisoning is uncommon. Moxon and Rhian^4 noted, that the early signs of acute poisoning are nervousness and fever, followed, by vomiting, then quietness and somnolence. Difficult breathing develops, fol- lowed by opisthotonos (tetanic spasm), clonic spasm, and falling blood pressure. Death may occur from respiratory failure, or convulsions resulting from action on the nervous system. ------- 2.1.3 Retention and Elimination Studies of Glover^4 and others12'19 indicate that there are no apparent long-term systemic effects in humans as a re- sult of chronic exposures to selenium and its compounds. Thus the body must have mechanisms for* the effective removal of se- lenium so that accumulation of toxic amounts do not occur. Animal experiments suggest that, at least at low concentrations, the urinary and fecal excretion rates attain a steady state during long periods of exposure to selenium. Results of studies by Smith et aj^.112 indicate that cats administered. d.aily oral doses of selenite (equivalent to 20 and. 100 (J.g of selenium per kilogram of body weight) excreted, approximately 75 percent of the selenium in the urine and. feces. When a toxic dose rate (equivalent to 250 |_ig/kg of selenium) was ad.ministered., the average excretion d.ropped. to approximately 64 percent of the total intake. The selenium not accounted for in the urine and. fecal excretion may be (1) retained in the body, (2) excreted as a volatile compound in the breath and. sweat, or (3) deposited, in the hair. The importance of the first possibility d.epend.s on the amounts excreted, by the latter routes. No experimental data are available for direct comparison of the contribution of each of the possible excretion routes. However, some d.ata indicate ------- 6 that excretion of volatile selenium compounds in the breath and sweat is a significant excretion route. Schultz and Lewis" found that when sodium selenate was administered subcutaneously to cats as sod.ium selenite in a dose equivalent to 2,500 to 3,500 |j.g of selenium per kilogram of body weight, 17 to 52 per- cent of the selenium was eliminated, as a volatile compound with- in 8 hours. In a similar experiment McConnell^ found that 3 to 10 percent of the initial subcutaneously administered sele- nite (equivalent to 3,000 to 4,000 U-g of selenium per kilogram of body weight) was exhaled in 24 hours—-half, moreover,- in the first 3 hours. Selenium is also deposited, in the hair in amounts dependent on the selenium concentration and duration of the exposure.^ According to Cerwenka and Cooper, ^ "Animal experiments indicate that as soon as a certain state of saturation is reached the excretion holds pace with the intake." If correct, this means that the maximum amount of selenium retained, in the body is dependent upon the level of exposure and not the d.uration of the exposure. This may not be true of ingested organic selenium compound.s. -*--*-^ The selenium that is retained is widely distributed in the body- Ermakov^l found, that selenium was wid.ely distributed in human organs and. tissues, and. that there was a significant ------- difference in the distribution pattern among individuals. Animals chronically exposed to toxic amounts of selenite are found to retain most of the selenium in the liver, kidney, spleen, pancreas, heart, and lungs.^9 Once removed from expo- sure to selenium, the animals rapidly eliminated almost all the selenium in the body, mainly in the urine within about 2 o ] 1 9 weeks. ' After this period elimination rapidly decreases to a very slow rate that continues for a month or longer. Ingested organic selenium appears to be retained, in the body longer than the inorganic selenium compound.s. H-^ 2.1.4 Detoxification In the human body natural detoxification occurs through reduction of selenium compounds to elemental selenium, which is apparently not toxic1^ and is excreted, through the kidneys and liver-->3/108 Elemental selenium is also converted to a volatile compound., ->3 probably dimethyl selenide, ^ which is eliminated through the breath and sweat. There are several method.s of artificial d.etoxification or prevention of selenium poisoning, at least for animals. Animal stud.ies have shown that protein, particularly casein, can help prevent intoxication from small amounts of ingested selenium.46'70'107 Thus a high protein diet may be an impor- tant factor in protecting humans against chronic selenium ------- 8 poisoning. Several studies have shown that arsenic can coun- teract the toxicity of selenium in rats, 5/88 c|OgSf94 an<^ p£gS<_1 9 Amor and Pringle suggested the use of an arsenic tonic for pro- tection of selenium workers, but it has never been tried. Bromo benzene has been used to accelerate the excretion of selenium in the urine.^7 However, some investigators^ found that this com- pound, administered orally, produced no effect on the selenium content of the body. 2.1.5 Selenium in Nutrition Preliminary findings ind.icate that selenium may be a bene ficial element to humans. In Jamaica the protein-d.eficiency disease kwashiorkor, which is characterized, by an inability to gain weight, appears to respond favorably to a d.iet supplement of 25 ng of selenium as ft, ^"-d is el enodivaleric acid.. It has al- ready been demonstrated, that selenium is an essential d.ietary nutrient for animals.-'-'-'0/135 Selenium is prescribed for such animal diseases as congenital white muscle d.isease, selenium- responsive unthriftiness in cattle, exudative diathesis in poul- try, and hepatosis diaetetica in pigs, as well as for barrenness in ewes. 2.1.6 Elemental Selenium Stud.ies to date ind.icate that elemental selenium is rela- tively nontoxic. However, d.ust or fumes of selenium cause ------- irritation of mucous membranes when inhaled. The selenium par- ticulates are collected in the upper nasal passages and cause catarrh, nosebleed., and loss of the sense of smell.^ Dermatitis can also occur when sufficient amounts come in contact with the skin.^ A d.etailed. description of an industrial exposure to red selenium fumes is related by Clint on.-^ Exposure to the fumes, which have an unpleasant, sour, garlic-like odor, resulted in immediate and intense irritation of the eyes, nose, and throat. Heavily exposed, workers noted, a severe burning sensation of the nostrils, immediate sneezing, coughing, nasal congestion, dizzi- ness, and red.ness of the eyes. Two to four hours after the ex- posure, severe head.aches, mainly in the frontal region, were experienced., and. lasted, until the following day. The most heavily exposed, workers had edema of the uvula and. slight dif- ficulty in breathing, while more pronounced dyspnea was noted in one case. No selenium could, be found, in the urine, and af- ter 3 d.ays all workers were entirely well and suffered no per- sistent aftereffects. 2.1.7 Selenium Dioxide, Selenites, Selenates Selenium d.ioxid.e (SeO2) and. selenite salts (SeO3 2) read.ily form selenious acid, in the presence of moisture. Se- lenious acid. and. its precursors are among the more toxic and ------- 10 irritating compounds of selenium. Exposure to selenium dioxide has been reported to cause severe dermatitis^ an<3 burning of the eyes, with intense pain, lacrimation, and congestion of the conjunctiva. 6 Glover43 noted that some people, particularly fair-haired workers, appear to become allergic to selenium di- oxide; thus, on walking into a room where selenium dioxide is present their eyes will puff up, while others in the room ex- hibit no ill effect. In general, susceptibility to the toxicity of selenium compound.s varies wid.ely from one individ.ua! to another. 2.1.8 Hyd.roqen Selenide Hyd.rogen selenid.e (H3Se) at room temperature is a gas with a very offensive odor.-^ This selenid.e, probably the most toxic and irritating of selenium derivatives, can be formed, by the reaction of selenium with organic matter or certain other elements, as well as from selenid.es by acid.s or in some cases by water. The symptoms of hyd.rogen selenid.e poisoning include nau- sea, vomiting, metallic taste, garlic od.or of the breath, dizzi- ness, extreme lassitud.e, and. fatigability. ' /2° These symptoms were observed, in one case from exposure to 800 |ag/m3 (0.2 ppm) of hyd.rogen selenide for less than 1 month. The symptoms of acute hydrogen selenid.e poisoning were d.escribed. by Symanski ------- 11 as acute irritation of the mucous membrane of the respiratory tract, pulmonary edema, severe bronchitis, and bronchial pneu- monia. Dudley and. Miller29 noted that a person rapid.ly loses his ability to detect the od.or of hydrogen selenide because of olfactory fatigue. These authors also mention that 5,000 |ag/m3 of this substance was intolerable to man and. caused, ocular and nasal irritation. 2.1.9 Selenium Oxvchlorid.e Selenium oxychlorid.e is a liquid, which is used, as a sol- vent for paints and varnishes, as a chlorinating agent, and as a resin plasticizer. Although it is strongly vesicant2? and the vapors toxic, the danger of poisoning is not as great as might be supposed, since the oxychloride has a low vapor pres- sure and readily d.ecomposes in air. 2.1.10 Organoselenium Compound.s There is a very limited, amount of data on the organic selenium compound.s. Motley _et_ aJL.. ^ reported acute sore throats in three laboratory workers following exposure to dimethyl selenide or combined organoselenium from hand.ling d.ogs injected, with sele- nium. One worker contracted pneumonitis. ------- 12 2.2 Effects on Animals Most reported, cases of animal poisoning result from the ingestion of plants or foods containing toxic amounts of sele- nium, usually bound with organic compounds. Cases involving cattle, sheep, horses, and hogs have been described.^7 Numerous animal experiments involving selenium and its compounds have been reported. The results of some of the experiments have al- ready been discussed in the sections concerned with Effects on Humans. Selenium from different sources produces different clinical and pathological symptoms in animals because of the various selenium compounds present in the sources. For example, Rosenfeld and Beath"' give the following order of toxicity from equivalent amounts of selenium from different sources: wheat > corn > barley > selenite > selenate. However, in animals, sub- acute poisoning from selenium in general produces pneumonia, fatty degeneration of the liver, and. degeneration of kidney cells and. these symptoms clear up without resid.ual pathology when exposure is discontinued. There is also evid.ence suggesting that selenium may cause cancer of the liver in rats. Studies have shown that selenium is a necessary dietary 0-7 element for many animals, including mammals and bird.s. 2.2.1 Livestock Acute poisoning of livestock occurs from the consumption ------- 13 of highly seleniferous weeds-—usually in a single feeding—-in many cases resulting in d.eath in a few hours . When the acute poisoning begins to take effect, the movement and posture of the animal become abnormal. Diarrhea usually follows, the tem- perature rises, and the pulse becomes rapid and weak. Respira- tion becomes labored, with mucous rales and possible blood froth from the air passages. Bloating is usually pronounced, accom- panied by abdominal pain, and urine excretion increases greatly- Pupils dilate. Complete prostration and. apparent lethargy occur just before death from respiratory failure. Emesis, diarrhea, apathy, and paresis have been noted in pigs suffering from se- lenium poisoning. Chronic poisoning can be d.ivided into three types, de- pending on the source of selenium: (1) blind, staggers, caused by organic selenium compound.s (with or without small amounts of selenate), which can be read.ily extracted, with water from native selenium-bearing plants; (2) alkali d.isease, produced, from con- sumption of plants or grains containing protein-bound, selenium which is insoluble in water; and (3) chronic selenium poisoning, prod.uced. experimentally from pure inorganic selenium compounds. A summary of the three diseases is given in Table 1, which has 97 been compiled from the studies cited by Rosenfeld and Beath. (See paragraphs under Section 2.3 for a d.iscussion of plants containing selenium.) ------- TABLE 1 SYMPTOMS AND GROSS PATHOLOGY OF CHRONIC SELENIUM POISONING IN LIVESTOCK 97 Blind Staqqers Alkali Disease Experimental Selenosis Selenium source Symptoms Gross pathology Certain selenium "indicator1' plants 1st stage: increased desire to eat, animal staggers 2nd stage: increased loss of muscular control, front legs become very weak, does not eat or drink 3rd stage: paralysis, nearly blind, abdominal pain, body temperature drops, emaciation, eyes swollen and inflamed, cornea cloudy, death usually occurs in 3rd stage Necrosis (with cirrho- sis) of liver, nephritis (subacute and chronic), enlarged gall bladder, soft and flabby heart, impacted intestinal tract with irritation Seleniferous grains and grasses Lameness, loss of vitality, elongated and hardened hoofs, loss of hair from mane and tail, anemia, stiffness of joints, roughened coat Atrophy and cirrhosis of liver; chronic nephritis; soft, flabby, and atrophied heart; edema of lungs Selenite and selenate inorganic salts Emaciation, some loss of muscle control, trembling of skeletal muscles, anorexia Necrosis with occasional cirrhosis of liver, acute nephritis, ulceration and gangrene of intestinal tract ------- 15 2.2.2 Experimental Animals Selenium poisoning in animals from administration of selenium and its compounds may be acute, subacute, or chronic, depending on the compound, dose, and duration of the exposure. Acute symptoms in animals are garlicky od,or, nervousness, fear, vomiting, and diarrhea.97 This is followed by quietness and somnolence, difficult respiration, and. decreased reflexes. Opisthotonos (tetanic spasm in muscles) follows. The blood pressure continually drops until d.eath results from respiration failure. In rats, subacute and chronic selenosis produce loss in body weight and. anorexia, followed, by cachexia, while ascites edema may also develop. ' Smith et aj...-'••'-^ noted that among the common laboratory animals the cat showed the greatest susceptibility and the rat the greatest resistance to selenium poisoning. 2.2.2.1 Selenium, Selenites, Selenates Hall _et_ aj.,.50 exposed, cats, guinea pigs, and. rabbits to elemental selenium dust (which may have been contaminated with selenium d.ioxide) at the concentration of 30,000 |ag/m3 for 16 hours. This exposure prod.uced. mild, interstitial pneumonitis in the animals. Selenium fumes via vacuum evaporation cause acute toxic reactions in rats. ------- 16 The susceptibility of animals to the toxicity of sodium selenite and selenate has been stud.ied. by Franke and, Moxon, ^»40 Heinrich and MacCanon,60 and. Painter.87 Sodium selenite appears to be more toxic to rats than sodium selenate by a factor of 1.5 to 1.6. A comparison of the toxicity of selenium compounds with that for compounds of tellurium, arsenic, molybdenum, and. vana- d.ium is given in Table 2. 2.2.2.2 Hydrogen Selenide Dudley and Miller^°'^^ investigated, the effect of inhala- tion of hyd.rogen selenid.e (H3Se) on guinea pigs. All guinea pigs exposed, to H2Se in the concentration of 20,000 Hg/m3 for 60 minutes d.ied within 25 d.ays; 93 percent of the guinea pigs inhaling 43,000 [ag/m3 for 30 minutes d.ied. within 30 d.ays; and after 570,000 |Jg/m3 for only 10 minutes, all guinea pigs d.ied within 5 days.28 Ad.d.itional stud.ies were cond.ucted. on guinea pigs with various concentrations ranging from 1,000 to 45,000 [jg/m3 of H2Se and. for period.s of 2, 4, and. 8 hours. Table 6 in the Appendix summarizes the reported data. The major cause of the d.eaths seemed to be pneumonitis caused, by irritation of the respiratory tract. In ad.dition, damage to the liver and spleen was observed.. At concentrations of 7,000 [ig/m3 and less no response was observable in the guinea pigs during the expo- sure period.s. In one experiment (8 hours at 42,000 |Jg/m3 ) it ------- 17 TABLE 2 MINIMUM DOSES FATAL TO RATS OF COMPOUNDS OF SELENIUM, TELLURIUM, ARSENIC, VANADIUM, AND MOLYBDENUM Compound MFD 75/48 hr* Sodium selenite (Na2SeO3) 3,250 - 3,500 Sodium selenate (Na2SeO4) 5,250 - 5,750 Sodium tellurite (Na2Te03) 2,250 - 2,500 Sodium tellurate (Na2TeO4) 20,000 -30,000 Sodium arsenite (Na2HAsO3) 4,250 - 4,750 Sodium arsenate (Na2HAsO4) 14,000 -18,000 Sodium vanadate (NaVOs) 4,000 - 5,000 Ammonium molybdate ((NH4)6MO7O24) >160,000 *Minimum fatal dose to at least 75 percent of the rats in 48 hours (in micrograms of compound per kilogram of weight) via intraperitoneal injection. ------- 18 was noted that the guinea pigs spread selenium-containing exu- date over their bodies which caused irritation of eyes and nose. 2.2.2.3 Organoselenium Compounds Q o Q *3 Moxon and co-workers ^' found that in general the or- ganic compounds are retained by the tissues to a greater extent, and for a longer period, of time, than are the inorganic com- pounds. However, there is a wid.e variation in the toxicity of different organoselenium compounds. The lethal d.oses for some organic compounds for rats via intraperitoneal injection are: for selenocystine, the equivalent of 4,000 |_ig of selenium per kilogram of body weight; for n-propylseleninic acid., 20,000 to 25,000 ng selenium; for B-selenodipropionic acid, and for B, B - diselenodipropionic acid, 25,000 to 30,000 ug selenium.®^,83 Animal experiments with dimethyl selenid.e indicate that this compound has a low degree of toxicity in mice and. rats7^ when injected intraperitoneally. 2.2.3 Carcinocfenesis There are d.ata which ind.icate that selenium may be car- cinogenic to animals, and therefore possibly to man. However, further investigations are need.ed. to clarify the point. In studies mad.e by Nelson _e_t aJ^.85 and. Fitzhugh et_ al_. ,3S 126 rats were fed. selenium in organic combination with corn and wheat (containing 5 to 10 ppm selenium) and. also inorganic selenid.es ------- 19 (10 to 50 ppm). Of the 53 rats that lived, over 18 months, 11 developed hepatic neoplasms of low malignancy, and, four devel- oped microscopic ad.enomatoid hyperplasias. None of the neo- plasms metastatized.. Rats that died before 18 months did not exhibit neoplasms. On the basis of these early tests, the Food Additive Amendment of 1958 included selenium in the cancer clause.'*-'- Concern for the carcinogenic hazard of selenium in foods was also shown by the National Acad.emy of Sciences ^ and the World Health Organization.^2 However, it was thought by some people that the d.ata were insufficient to prove the carcinogenic hazard.s of selenium, and they urged a careful reevaluation of the problem. Some suggested that the d.iet in the experiments of Nelson et. al_. -* was inad.e- quate in protein. Pearce failed, to ind.uce cancer in rats by sodium selenite feed.ing, but the experiment was terminated be- fore 18 months, the time that the Nelson experiments began pro- d.ucing "cancer." Clayton and. Baumann 5 found, that 5 ppm of sodium selenate appeared to d.ecrease the susceptibility to azo- dye-induced cancer of the liver. Furthermore, although the hepatotoxicity of excess selenium is well known, no report of liver cancer resulting from chronic selenium poisoning in farm animals has been found, in the literature. ------- 20 cited the work of Tsuzuki .et. aj._. ,-^23 W]1O studied rabbits and mice under conditions simulating industrial exposure to selenium vapor and exposure to selenium metal dust. The au- thors reported, that tumors formed in the subcutaneous tissue of the d.orsal neck in some of the mice after unusual exposures to selenium. The tumors were considered, to be ad.enomas, similar histologically to cylindromas. The tumors apparently did not metastasize. 191 199 1 9 A Tscherkes and co-workers ^'-L^^'±^H: studied rats fed mixtures of sod.ium selenate (430 and. 860 jag Se/100,000 u.g of diet) and casein (12 to 30 percent). To some mixtures other ingredients were ad.d.ed, including riboflavin, cystine, chlorine, and. nicotinic acid. The overall tumor incid.ence was 8.5 per- cent of the 200 rats. Four rats developed, hepatoma neoplasms, two of which had. pulmonary metastasis. Sarcomas were found, in seven rats, one sarcoma in the liver and the others in the me- senteric lymph nod.es. There were four rats with adenomas and. the same number with precancerous tumor forms. Harr .et. ai_. -*7 also stud.ied. rats fed. selenites and sele- nates (from 0.5 to 16.0 ppm Se) with 12 or 22 percent casein added. No neoplasms were found, that could be attributed to the selenium in the diet. However, three types of lesions were found.: (1) acute toxic hepatitis associated, with osteodystrophy, ------- 21 icterus, and fluid imbalance; (2) chronic toxic hepatitis as- sociated with chronic passive congestion, reticulosis, myocar- ditis, productive pancreatic duct hyperplasia, hepatocyte hyperplasia, and. hepatic necrosis; and (3) hepatic hyperplasia associated with abnormal hepatic foci. 2.3 Effects on Plants No studies were found concerning the effects of atmo- spheric selenium on plants. However, it has been well established that certain types of plants require selenium to grow, that they can accumulate high concentrations of selenium from seleniferous soils, and that some will even emit volatile selenium compounds into the air. Furthermore, while some plants can store up very high concentrations of selenium (up to 10,000 ppm), others (e.g., corn and wheat) can be damaged by the accumulation of small a- mounts (300 ppm). Kubota _et_ _al_. summarized their work and others on the selenium content of plants in the United. States. Figure 1 shows the average selenium content of plants for 480 counties in 46 of the States. 2.3.1 Selenium Ind.icator Plants Plants that can grow only in soil containing selenium and can accumulate large amounts of selenium are referred, to as "Death's selenium indicators."^'97 A number of these plants' blossoms emit an offensive, garlic-like odor caused by the ------- + Counties in which greater than one-half of the plants contained less than 0.1 p.p.m. e Counties in which greater than one-half of the plants contained more than 0.1 p.p.m. • Counties were more than 50 p.p.m. of selenium was found in selenium-accumulator plants but no data available in selenium content of forages or grains. FIGURE 1 Selenium Content of Plants in Certain Counties in the United States6^ to ------- 23 production of volatile selenium compounds. To an experienced person the intensity of the odor provides an indication as to the amount of selenium in the plant, which is related to the amount in the soil. These "primary" indicators normally grow in the soil of arid and semiarid regions and are generally found in the Mid- western and Western parts of the United. States. Includ.ed. in the list of indicator plants are 24 species and varieties of Astragalus (milk vetch, with pea-like flowers), section Xylo- rhiza (woody aster) of Machaeranthera, section Oonopsis (gol- denweed) of Haplopappus, and Stanleya (princes plume). The geographical distribution of these plants is shown in Figure 2. These plants contain large amounts of selenium, generally 1,000 to 10,000 ppm. The consumption of these plants by live- stock prod.uces the disease synd.rome of blind staggers or acute selenium poisoning discussed in Section 2.2.1. 2.3.2 Secondary Selenium Absorbers Other types of plants also accumulate substantial amounts of selenium (generally 50 to 500 ppm), but less than the "indi- cator plants." However, they do not require selenium in the soil for growth. These secondary selenium absorbers includ.e species of Aster.- Atriplex, Castilleja, Camand.ra, Grayia, Gren- d.elia, Gutierrezia, Machaeranthera, and. Mentzella. They can be ------- FIGURE 2 Distribution of Seleniferous Vegetation ------- 25 used to indicate seleniferous soils through analysis of their selenium content. These secondary absorbers can accumulate only water- soluble selenium from the soil. This is in contrast to the in- dicator plants which can accumulate selenium from the soil regardless of the form of selenium present. The second.ary se- lenium absorbers may produce acute or chronic selenium poisoning when consumed by livestock. 2.3.3 Grains, Vegetables, Grasses, and. Other Vegetation Most grains, vegetables, and grasses could also be clas- sified as secondary selenium absorbers in that they may simi- larly absorb and accumulate water-soluble selenium compounds from the soil. However, the maximum amount of selenium that is accumulated by these plants is generally less than 30 ppm. Wheat, barley, corn, oats, and rye that have been grown in a seleniferous soil contain 0.1 to 30 ppm selenium. ^ vege- tables normally accumulate less than 1 ppm in selenium- containing soils, but values as high as 18 ppm have been noted. The content of selenium in native grasses is quite variable. They sometimes contain as much as 84 ppm selenium. ' Consump- tion of plants that contain high amounts of selenium usually prod.uces alkali disease in livestock. ------- 26 Crop plants are damaged by accumulation of large amounts of selenium (30 to 300 ppm). The most common symptom of sele- nium poisoning in plants is inhibition of growth. Some crops, particularly wheat, barley, and. rye, will exhibit chlorosis. Younger plants are more susceptible, and their growth inhibition is greater than that of mature plants. Hamilton and Beath-^' 55,56 have recently studied a large number of plants for their uptake and. distribution of various forms of selenium. These plants, includ.ing 20 range plants, 17 crop plants, and 18 vegetables, were stud.ied. while growing in an artificially selenized. soil und.er greenhouse cond.itions. It was found that the distribution of selenium within a plant var- ied, widely and. that all the plants could, accumulate toxic a- mounts of selenium. Other vegetation, including tobacco, also can accumulate selenium. However, because these types of vegetation accumulate only small amounts of selenium and have not poisoned animals, they have not been as well studied.. Dye _et_ aj^. 0 determined the selenium content of some plants as follows : ------- 27 Se Content Plant ppm (aver. ) Pear leaves 0.45 Apple leaves 0.53 Radish leaves 0.28 Lettuce leaves 0.60 Corn 0.32 Wheat 0.29 2.4 Effects on Materials There is no information at present indicating that at- mospheric selenium would have any detrimental effect on materi- als . 2 . 5 Environmental Air 5tand.ard.s The American Conference of Governmental Ind.ustrial Hy- gienists (ACGIH) has set the threshold limit values for occu- pational exposure during 40-hour weeks with 8-hour days at 200 f-ig/m3 for selenium compounds, except in 1967 when the limit for selenium hexafluorid.e was set at 400 |jg/m3 . In 1962, the value was lower, 100 |ag/m3 for selenium compounds.^4 No country has yet established, a 24-hour threshold, limit value. ------- 28 3. SOURCES 3.1 Natural Occurrence Selenium is widely distributed in the earth's crust at a concentration of about 0.09 pptn.45 However, it is mainly con- centrated in sulfide minerals and in the soil of the dry plains of the Midwestern United States. Furthermore, some plants can absorb and accumulate selenium in large amounts from the soil. (See Section 2.3 for a discussion of these plants.) Despite its wide distribution in nature, selenium is not an essential constituent of any common rock-forming mineral. However, it is recognized as a major constituent in at least 22 selenides, 6 sulfosalts, 1 oxid.e, 4 selenites, and. 1 selenate, and as a minor constituent of 24 sulfides and. tellurid,es, 5 sulfosalts, and 1 tellurite. The important selenium minerals are berzelionite (Cu2Se), tiemannite (HgSe), and. naumannite (AgsSe). Selenium is associated, mainly with copper, iron, lead, silver, gold, and uranium, and. is often found with pyrite, chalcopyrite, bornite, and, other sulfide minerals. y Weathering releases much of the selenium from these minerals; it may remain as native selenium or, more often, be redeposited. as ferric se- lenite in secondary iron minerals such as limonite. Luttrell ^ has prepared a partial list of selenium-bearing minerals. ------- 29 Selenium can be found in coal (see Section 3.4), igneous rocks, hydrothermal deposits, and sedimentary rocks.67 In ig- neous rocks and in sulfide ores probably most of the selenium is wid.ely distributed, as selenid.es. Volcanic rocks in various parts of the Western United. States contain as much as 120 ppm 22 34 selenium, ' and still higher concentrations are present in some volcanic sulfur d.eposits.10 Hyd.rothermal ore deposits containing high concentrations of selenium are widespread. Some of the more common are those associated, with epithermal gold and. silver deposits, as well as with antimony and. mercury epithermal d.eposits. Large amounts of selenium in small con- centrations are found, in copper deposits of the porphyry type and in massive sulfide deposits, such as those in the Southern Appalachians. Several studies have been made of sed.imentary rock for- mations (particularly in the Western United. States67), many of which support poisonous seleniferous vegetation. Beath et al. found that sand.stone from the Poison Butte area of Wyoming con- tains 112 ppm selenium, that carbonaceous siltstone in western Wyoming contains 680 ppm, and. that phosphate rock contains as much as 212 ppm selenium. The Pierre Shale of the Western United States, a carbonate rock, contains as much as 26 ppm selenium. Carbonate rock from the Phosphoria Formation in ------- 30 Idaho, Montana, Utah, and. Wyoming contains selenium ranging from 1 to 100 ppm, with an average of 19 ppm.67 Highly concentrated deposits of selenium have also been found in the volcanic tuff of the Wind River formation of Wyo- ming,34'120 and in sandstone-type uranium deposits, particularly in the Gas Hills area of Wyoming and the Ambrosia Lake district of New Mexico. Selenium cannot be mined, profitably, with the present method.s of technology, because of the low concentration of se- lenium in mineral d.eposits. Therefore, selenium must be d.e- rived as a by-product in the refining of other ores. 3.2 Production Sources Quantities of selenium in mineral deposits are not suf- ficient to make its extraction alone profitable. It therefore is obtained, as a by-prod.uct from other processes. The principal source of selenium is as a by-product from the copper refineries; smaller amounts are obtained from lead smelters and from the selenium-containing sulfur residues from the chemical ind.ustry-67 Other sources are the refining of various sulfid.e ores (gold, silver, nickel) and. uranium ores, as well as the making of paper (when pyrites are used, as the source of sulfur in the manufacturing process). ------- 31 In the smelting of copper ores, part of the selenium remains with the crude or blister copper (about 0.05 percent selenium), and part is carried through the flues as fumes and dust which are collected and. returned to the reverberatory 2 0 furnaces. Dust from the lead, smelters is also add.ed to this circulating stream of flue gases. In the electropurification of the copper, the selenium precipitates with other metallic products in the mud or slime that collects beneath the anode. This anode mud., ranging from about 0.05 to 10 percent selenium, is usually refined, by one of the following fundamental processes: smelting with soda ash, roasting with soda ash, and roasting with sulfuric acid to yield, about 98 to 99 percent pure selenium met- al, with arsenic as the major impurity. ^ High-purity selenium, used in electronics, is made by several method.s such as fractional d.istillation, zone refining, and. catalytic oxid.ation to selenium dioxide followed by either gaseous or wet red.uction. The United. States is the major producer and consumer of selenium. In 1967, six companies in the United States produced selenium.9 They are listed, in Table 7 in the Appendix. Of these, the Kawecki Chemical Company is a metal and alloy manu- facturing company. The remaining companies prod.uce selenium as a by-prod.uct in the copper refining process. Table 8 in ------- 32 the Appendix summarizes the production, apparent consumption, and price of selenium for 1956 through 1967 in the United States, 3 . 3 Prod.uct Sources Selenium has a variety of applications, but most require only small quantities of the metal. The major users are the electronic and electrical industries, in which 90 percent of the selenium is used, in the manufacture of d.ry plate rectifiers, while the rest is used mostly in photoelectric cells.20 The chemical industry is the next largest user, accounting for over one-third, of the total consumption. The glass ind.ustry and xerography manufacturing also use significant amounts. The major uses of selenium and its compound.s are as fol- lows : Rectifiers: These are used, extensively in electroplating, welding, d.irect-current motor operation, and. ind.uction braking, and in battery chargers, magnetic coils, arc lamps, and voltage regulators. About 0.5 to 25 g of selenium are used, per recti- fier, depending on cell size. Photoelectric cells; These cells, which require about the same amount of selenium as rectifiers, are used in photographic ex- posure meters, d.etectors, electric eyes, colorimeters, and. py- rometers . Pigments: The largest use of selenium by chemical industries ------- 33 is for pigments. Selenium is compounded with cad.mium sulfide to prepare the orange, red, and maroon cadmium sulfoselenide pigments used to color plastics, paints, enamels, inks, and rubber. Glass : Selenium, sod.ium selenate, barium selenite, and sodium selenite are ad.ded (0.02 to 0.3 Ib/ton of glass) to neutralize green tint from iron impurities in glass. A slightly larger amount is add.ed to prod.uce a pink tinge for such prod.ucts as milk bottles and other food containers. Ruby-red glass (used in tableware, vehicular taillights, traffic and. signal lights, light filters, and. infrared, equipment) requires about 1 to 50 pounds of selenium per ton of glass. Selenides of the arsenic groups are used, to make low-melting-temperature glasses, pri- marily for research purposes. Lubricants ; Tungsten diselenid.e (WSe2 ) and. columbium diselenid.e (CbSes) powders are used as solid, lubricants directly applied to rubbing surfaces or mixed, with other greases and with various metals, ceramics, and. plastics to form self-lubricating parts. Applications include the vacuum, rad.iation, aerospace, electro- mechanical, and instrumentation fields. Blasting caps; Selenium, with barium peroxide and tellurium, is used, for variable, delayed.-action, gasless fuse powder in blasting caps. Almost 10,000 pounds of selenium and tellurium mixture are used, annually in this capacity. ------- 34 Chromium plating; Selenate solutions, ranging from 0.012 to 0.020 g/liter, are used in chromium-plating solutions which im- part a superior corrosion-resistant property and a dull luster (for prevention of glare) to the plated, material. Stainless steel: Selenium improves the casting, forging, and machinability of stainless steel without reducing its corrosion resistance or hot-forging and cold-working properties. Selenium content varies from 0.01 to 0.35 percent. Medicines: In the form of sod.ium selenate solution, selenium is used to control certain animal diseases49 such as congenital white muscle disease in sheep, selenium-responsive unthriftiness in cattle, exudative diathesis in poultry, and. hepatosis diaete- tica in pigs. This solution is also used to overcome sterility in ewes. Photocopiers: Amorphorus selenium is used in the xerography process. There are many minor uses of selenium and. its compounds, such as: in preparation of Pharmaceuticals (e.g., niacin and cortisone); in deodorants; as accelerating and vulcanizing agent in rubber products; as catalysts for oxidizing, dehydro- genating, and. hardening of fats used in soaps, waxes, edible fats, and plastics; in printing inks, transformer oils, mineral oils, and. vegetable oils as an antioxid.ant; in linseed., oiticica, ------- 35 and tung oils for nondrying properties; in insecticides, para- siticid.es, bactericid.es, and herbicid.es; in photographic photo- sensitizers and toners; in mercury vapor detectors; as fire- proofing agents for textiles and wire cable coverings; as insect repellants; as phosphorescents and. luminescents. Selenium oxy- chlorid.e is a powerful solvent used, as a paint and. varnish re- mover and. for rubber resins, glue, and. other organic substances. Applications which appear to be increasing are xerography copying; steel prod.uction; preparation of red color television phosphor (ZnSe), electrolytic manganese, and colored anodized. aluminum; and. use in solid lubricants. There are new applica- tions of selenium in animal health and nutrition. No recent figures could, be found, provid.ing a breakdown by uses of the consumption of selenium and. its compounds; how- Q Q ever, Minerals Yearbook includes a breakdown of the consump- tion for 1955. A list of merchandisers and consumers of selenium and its compounds is given in Table 9 in the Appendix, while Table 10 in the Appendix lists some selenium compound.s and their uses, and. Append.ix Table 8 includ.es consumption and price statistics. 3.4 Other Sources Selenium air pollution may occur from the heating or burning of materials that contain selenium. Thus incineration ------- 36 of manufactured selenium products (see Section 3.3) may be a pollution source if not properly controlled.. In addition, the burning of coal and other natural materials that contain sulfur can also be a source of selenium pollution. Normally where sul- fur is found., selenium can also be found. Materials from ter- restial sources such as fuels and. ores generally have a selenium- to-sulfur ratio of approximately 1 x 10~4. " Little information is available on the selenium content of the various materials and products that are incinerated every d.ay. Some possible sources of selenium include natural fuels/ leather good.s, cloth materials, wood, prod.ucts, etc. West-^O has found, selenium in paper products including ciga- rette paper, newspaper, etc. (see Section 3.5). Lakin and Davidson*^ summarized, the data on the selenium content of dif- ferent coals. As can be seen from Table 3, the selenium con- tent has been found as high as 7.38 ppm selenium in lignite coal. ------- 37 TABLE 3 SELENIUM CONTENT OF COALS 66 Type of Sample Location Coal Western Wyoming Lignite Montezuma County, Colo. Sand oval County, N. Mex. Morley, Alberta, Canada No. of Selenium Content (ppm) Samples Ranqe 3 1.96-7.38 2 2.0-2.4 1 1 Average 3.88 2.2 0.1 2.0 3.5 Environmental Air Concentrations Only one published report was found, relating to the at- mospheric concentration of selenium in the United. States. Hashimoto and Winchester-^ in 1964-1965 measured the selenium content in samples of rain, snow, and air collected, on the cam- pus of the Massachusetts Institute of Technology (Cambridge, Mass.), in the semirural areas of Topsfield and Boxford, Mass., and in the smaller city of New Haven, Conn. The d.ata are shown in Table 4. In Cambridge, the average selenium concentration was 0.21 \J.g per liter of precipitation, which on the basis of air samples is approximately equivalent to 0.001 |-ig/m3 of air or 1 nanogram per cubic meter. Air samples (100 m3 ) were taken by passing air (1 m3/hr) either through an aqueous bub- bler or through a 1-micron pore diameter Millipore filter. ------- 38 TABLE 4 ATMOSPHERIC SELENIUM (1964-65 J59 Location3 Date 1964-65 Se in , ,~b Remarks 1 2 1 2 1 2 1 2 1 2 3 2 3 2 3 1 2 Mean 4 5 5 6 6 1 5 1 1 1 1 1 1 1 Dec. 18 Dec. 18 Jan. 3 Jan. 3 Jan. 10 Jan. 10 Jan. 16 Jan. 16 Jan. 24 Jan. 24 Feb. 22 Feb. 25 Mar. 20 Mar. 20 Mar. 29 Mar. 29 Mar. 29 Jan. 31 Feb. 27 Mar. 20 Mar. 20 Mar. 20 Feb. 27 May 11 May 20 May 20 May 27 May 27 June 1 June 1 0.15 0.09 1.40C 0.70 0.13 0.16 0.53 0.52 0.14 0.16 0.25 0.10 0.08 0.06 0.10 0.09 0.10 0.21 0.08 0.03 0.12 0.04 0.10 0.11 0.09 0.03 0.03 0.11 0.13 0.16 0.06 0.10 Falling Falling Rain + Rain + Falling Falling Falling Falling Falling Falling Falling Rain Ground Falling Ground Falling Falling snow snow ice ice snow snow snow snow snow snow snow snow snow snow snow snow Ground snow Ground snow Ground snow Ground snow Ground snow Tap water Well water Air, bubbler Air, bubbler Air, filter Air, bubbler Air, filter Air.- bubbler Air, filter aSampling locations: 1. MIT campus, roof of earth science building. 2. Ground location near 1. 3. Cambridge, near Central Square. 4. Topsfield, Mass. 5. Boxford, Mass. 6. New Haven, Conn., Yale University campus. Micrograms of selenium per liter of water or 100 m of air. One liter of water is roughly equivalent to 200 m3 of air. GExcluded from mean. ------- 39 The rain or snow melt water (1 liter) was collected on poly- ethylene, filtered on filter paper to remove particulates, acidified, evaporated to a final volume of 0.1 ml, and analyzed by neutron activation. The bubbler solutions were processed similarly, while the Millipore filters were irradiated directly. Based, on the selenium-to-sulfur ratio (1 x 10~4 ) , which is similar to that found for geochemical materials, these au- thors conclud.ed that the source of the selenium was probably from terrestrial sources, including fuels and ores used by in- dustry. The authors also suggested that a study of the sele- nium-to-sulf ur ratio in different locations may give some information about the length of time the selenium has been in the air and. the sources of pollution. Some unpublished, results on the selenium content of particulates for various cities in the United. States is given in Table 5. The particulate matter was collected from am- bient air. The analytic procedure involved, extraction of the samples with hydrochloric acid and. analysis of the extract by atomic absorption spectrophotometry. A study is presently being conducted, by Dr. Philip W. West-^O to determine the selenium content of air in Baton Rouge, La., and possibly in other areas. The preliminary investigation shows that there is a d.etectable amount of selenium in Baton ------- 40 TABLE 5 SELENIUM CONTENT OF PARTICULATES IN AMBIENT AIR, 1965 Location Selenium Content ( ug/m3 ) * California (Los Angeles) <0.06 Colorado (Denver) <0.05 Arizona (Phoenix) <0.04 California (Long Beach and San Francisco) " Connecticut (Norwich) " Delaware (Newark and Wilmington) " District of Columbia " Hawaii (Honolulu) " Illinois (Chicago and East St. Louis) " Indiana (Dunes State Park, East Chicago, " Indianapolis, Ogden Dunes) Kentucky (Lexington) " Louisiana (New Orleans) " Maine (Portland) " Massachusetts (Lawrence) " Michigan (Grand Rapids) " Minnesota (St. Paul) " Missouri (St. Louis) " Montana (Helena) " Nevada (Las Vegas) " New Jersey (Glassboro, Marlton, " Pemberton, Trenton) *Values given are averages of 1965 quarterly composite of 5 to 7 samples; an air volume of 2,000 m (25°C) is assumed. ------- 41 Rouge, and that the probable source is trash burning. It was found that paper and other prod.ucts of vegetation had. a high concentration of selenium; for example, newsprint was found, to contain up to 6 ppm selenium. The selenium content was thought to be a result of the accumulation of selenium in the initial tree or plant. However, Cole thought that selenium could be introduced into paper from the pulping chemicals (e.g., the use of pyrites for the source of sulfur). Lakin and Davidson reported the results of analysis of particulate matter for selenium in 1941. The samples were collected from air-cond.itioner filters in various locations, as shown in Table 11 in the Appendix. The selenium content ranged from 0.05 to 10 ppm. ------- 42 4 . AB AT EMENT No study has been made of the methods for control of se- lenium and its compounds. However, based on the properties and on the methods of recovery and. purification of selenium, wet scrubbers and high-voltage electrostatic precipitators should be effective. The common selenium atmospheric pollutants are probably selenium dioxide (or selenious acid, in moist environ- ments) and., to a lesser extent, hyd.rogen selenid.e. These com- pounds are all soluble in water, the former a solid and the latter a gas at ambient temperatures. Selenium metal, except for the red. allotrope form, is insoluble in water. However, it is soluble in strong bases, forming selenium compound.s, and it will burn in air, producing selenium dioxide. In the recovery and. purification processes of selenium,^ wet scrubbers and. electrostatic precipitators are used to col- lect selenium dioxide fumes given off d.uring the smelting or roasting, as well as to collect red selenium. Furthermore, selenium emissions from trash burning are controlled by the i "3 o use of wet scrubbers. At the present time, the chief industrial control methods are the use of a good, ventilation system and. personal pro- tective equipment, includ.ing safety goggles and. a respirator when working in a low airborne concentration, and a supplied-air ------- 43 \ . respirator in heavily contaminated areas. ^ Selenium-containing liquid wastes are disposed, of by washing them down the drain, while solid wastes are buried. ------- 44 5. ECONOMICS No information has been found on the economic costs of selenium air pollution or on the costs of its abatement. Data on the production and. consumption of selenium are presented in Section 3. ------- 45 6. METHODS OF ANALYSIS 6.1 Sampling Methods Air samples have been collected by means of electrostatic precipitators,89 filters,59 and liquid impingers.59'63'89 All of these methods can be used for selenium dusts and fumes, while only the last can be used for collection of vapors or gaseous compounds. The use of filters and. liquid impingers are the most commonly used sampling method.s tod.ay. Some air samples were taken by passing 100 m3 of air at the rate of 1 m3/hr through a 1-micron pore d.iameter Millipore filter. Because selenium is found, in many filter papers, Millipore filters or other selenium-free collection med.ia (e.g., glass fibers) should be used. However, some filter papers can be washed, with sodium sulfid.e and water to remove traces of selenium. The liquid used in the impingers has been water59'63 an(3 a solution of 40 to 48 percent hydrobromic acid with 5 to 10 percent bromine. The water can be used, with nonvolatile water-soluble compound.s such as selenium d.ioxide. The ad.vantage of the hydrobromic acid.-bromine solution is that it converts selenium and. most of its compounds to the soluble selenium tetrabromid.e. This solu- tion, after collection, can be analyzed directly after decolori- zation and neutralization,63 or the selenium may be separated by d.istillation. ------- 46 It has also been suggested, that soda lime or silica gel could be used, to collect vapors of selenium compounds.89 6 .2 Qualitative Determination Method.s A quick qualitative estimation of selenium can be made by taking advantage of the reaction of aromatic 1,2-diamines with selenious acid, (or Se(IV) cation) to form colored, piasele- noles. Elemental selenium and selenides readily oxidize in ni- tric acid or hydrogen peroxide to selenious acid. Selenate salts—or Se(Vl) cations—give only weak colors. The most com- mon diamine employed is 3, 3 '-d.iaminobenzidine, which forms a yellow dipiaselenole in acid and is sensitive to 10 ppm. The 4-dimethylamino and 4-methylthio derivatives of 1,2-phenyl- enediamine will also react with selenious acid, to give stable bright red and. blue-purple colors, respectively- Reaction with 2,3-diaminonaphthalene has been used as a spot test.35 other ions—particularly copper, iron, tellurium, chromium, nickel, and cobalt—may cause interference in high concentration, but some may be masked, by complexing agents such as EDTA. Other methods of detection of selenious acid that have been reported are reaction with (1) iodides,91 (2) thiourea,23 (3) diphenyl- hyd.razine, 36 and. (4) pyrrole,114 as well as the catalytic ef- fect on the reaction of methylene blue with alkali sulfide. ------- 47 6.3 Quantitative Determination Methods Several quantitative methods of analyzing selenium are based on the reaction of selenious ion with 3,3'-d.iaminobenzi- dine. West and Cimerman used, this reagent in connection with the ring-oven technique. This colorimetric method is basically free from interferences when masking reagents are used; limit of identification is 0.08 p.g, is applicable in the range of 0.1 to 0.5 lag.129'131 Kawamura and Matsumoto63 spectrophotometrically determined the selenium in air samples collected in impingers by measuring the absorbance of the solutions treated, with this reagent. The benzid.ine reagent has also been used, in fluoro- metric determination of selenium in biological materials. ' Detection in these method.s was in the ord.er of 10 to 50 ppb selenium. Walk ins on, •*- as well as Allaway and Gary,-*- found, that the product from 2,3-diaminonaphthalene and selenium showed a fluorescence sensitivity in the neighborhood of 0.5 to 5 ppb selenium—a sensitivity greater than that with the benzid.ine prod.uct. Neutron activation methods have been used, to determine selenium from air samples (via filters and. aqueous bubbler) and from samples of snow and. rain.59 A sensitivity of 0.01 |j.g of selenium was obtained, when gamma rad.iation was measured, with a ------- 48 scintillation spectrometer. This technique has also been used to determine traces of selenium in biological materials and in metals,18 Recently West and Ramakrishna-*-^ have developed a method for determining trace amounts of selenium based, on its catalytic effect in the red.uction of methylene blue by sodium sulfite. Color comparisons are mad.e in the range of 0.1 to 1.0 |~ig of se- lenium. There is serious interference from copper if present in an excess of 10 [ig. Kawashima and Tanaka64 also developed a catalytic method based, on the reduction of 1,4,6,11-tetraaza- naphthacene; this method is subject to interference from several ions. Walkinson-^? has d.iscussed some of the newer methods that are used, in the analysis of selenium in biological material, in- cluding polarography, X-ray fluorescence, and. atomic absorption spectrophotometry- ------- 49 7. SUMMARY AND CONCLUSIONS Selenium compounds, particularly the water-soluble com- pounds, are toxic to humans and animals. In humans, mild, in- halation of selenium d,usts, fumes, or vapors irritate the membranes of the eyes, nose, throat, and. respiratory tract, causing lacrimation, sneezing, nasal congestion, coughing, etc. Prolonged exposure through inhalation can cause marked pallor, coated tongue, gastrointestinal disorders, nervousness, and a garlicky odor of breath and. sweat. In animals, subacute sele- nium poisoning prod.uces pneumonia and degeneration of the liver and kidneys. Furthermore, experiments with rats ind.icate that selenium may cause cancer of the liver. The biochemical effects of elemental selenium and. its compounds on humans is not as yet thoroughly understood. The selenium deficiency diseases found in animal species, as well as some of the frank selenium poisoning, have not been observed in man. Similarly, the carcinogenic hazard of selenium and. the antagonistic effect of arsenic for selenium seen in animals are yet to be shown in humans. These are important factors that need clarification to properly evaluate the role of selenium and its compounds in air pollution. There is no information ind.icating that atmospheric se- lenium has any detrimental effect on plants or materials. Some ------- 50 plants contain large amounts of selenium that can be toxic to the plants themselves, as well as to humans and animals who in- gest the plants. Samples of snow/ rain, and. air taken in Boston, Mass., (1964-1965) show that the selenium content of the air is aver- aging 0.001 |ag/m3 . Based, on the selenium-to-sulfur ratio in these samples, the atmospheric selenium was probably from ter- restrial sources, including the fuels and. ores used by ind.ustry. Another source may be the burning of trash containing paper products. Some papers when analyzed contain as much as 6 ppm selenium. Selenium in paper may come from accumulation by the original tree or plant, or possibly from the manufacturing of the paper (from the use of pyrites in the process). Any vege- tation which is burned, may be a possible source of atmospheric selenium. Another source could be the refining of sulfide ores, particularly copper and. lead ores. Emissions of selenium and its compounds can be effectively controlled by use of electrostatic precipitators and. water scrub- bers . No information has been found, on the economic costs of selenium air pollution or on the costs of its abatement. Method.s of analysis are available that can measure quantitatively in the parts per billion or submicrogram region. However none ------- 51 of the methods is simple, rapid, or applicable to continuous monitoring, and many of the method.s are not specific for sele- nium. A rough estimate as to the magnitude of selenium in the atmosphere might be made from the concentration of sulfur in the atmosphere. This method would, be valid, if the sources of these two pollutants are sulfid.e ores, fossil fuels, or igneous and. sed.imentary rocks, since in these materials the average weight ratio of selenium to sulfur is 1 x 10~4. Based on the material presented in this report, further studies are suggested, in the following areas: (1) Further determination of the atmospheric concentra- tion of selenium compounds in the cities of the United States, particularly near copper refiners and other sulfide ore re- finers, and near trash-burning sites. 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Food Chem., JL1_: 355 (1963). ------- APPENDIX ------- APPENDIX TABLE 6 MDRTALITY OF GUINEA PIGS FROM INHALATION OF HYDROGEN SELENIDE 29 Number of Concentration Guinea (ufj/m )* Piqs Days 1-5 Days 6-10 Days 11-15 Days 16-20 Days 21-25 .Days 26-30 % Dead Within 30 Days 2-hour exposure: 6, 12, 13, 21, 34, 36, 000 000 000 000 000 000 16 16 16 16 16 16 0 3 1 4 5 11 0 2 6 2 0 3 1 2 0 5 3 0 1 1 2 2 3 1 0 0 1 1 0 0 0 0 0 0 0 0 12 50 62 87 68 93 .5 .0 .5 .5 .8 .7 4-hour exposure: 6, 7, 12, 15, 45, 000 000 000 000 000 16 16 16 16 16 1 2 2 8 15 2 0 6 5 1 0 1 3 1 0 1 1 1 0 0 0 1 0 0 0 18 25 75 100 100 .8 .0 .0 .0 .0 8-hour exposure: 1, 1, 1, 6, 6, 7, 42, 000 000 000 000 000 000 000 Controls 16 16 16 16 16 16 16 32 0 1 0 15 7 5 14 1 2 3 7 3 3 2 2 1 4 1 2 2 0 5 0 0 1 0 2 3 1 1 1 0 0 1 1 1 0 1 2 0 0 0 0 0 50 50 56 81 87 87 100 9 .0 .0 .3 .3 .5 .5 .0 .4 co *1 (ag/m3 = 0.000302 ppm. ------- 64 APPENDIX TABLE 7 80 PRODUCERS OF SELENIUM IN THE UNITED STATES (1967) Company Location American Metal Climax, Inc. Carteret, N.J. American Smelting and Refining Co. Baltimore, Md. International Smelting and Refining Co. Perth Amboy, N.J. Kawecki Chemical Co. Boyertown, Pa. Kennecott Copper Corp. Magna, Utah Kennecott Refining Corp. Anne Arundel County, Md. ------- APPENDIX TABLE 8 SALIENT SELENIUM STATISTICS, 1956-6778'79'80 (Thousands of pounds of contained selenium) ited States Production3 Shipments to consumers Imports for consumption Consumption, apparent*5 Producers ' stocks, Dec. 31 Price per 1956 928 1,035 235 1,270 191 1957 1,077 625 148 773 651 1958 727 737 184 920 551 1959 799 1,011 224 1,234 339 1960 620 650 160 810 290 1961 1,022 787 117 904 515 1962 999 741 159 900 773 1963 928 679 339 1,018 1,022 1964 929 646 293 939 1,305 1965 540 824 251 1,075 1,021 1966 620 845 286 1,131 797 1967 598 659 301 960 736 pound, commer- cial grade World produc- tion $9.00- 15.00 1,923 $7.50- 12.00 1,940 $7.00- 7.50 1,507 $7.00 1,719 $6.50- 7.00 1,777 $5.75- 6.25 2,097 $5.75- 6.25 2,091 $4.50- 5.75 2,015 $4.50- 6.00 2,163 $4.50- 6.00 1,789 $4.50- 6.00 1,951 $4.50' 6.00 2,069 ^Includes small quantity of secondary selenium for 1956-61. Total of shipment and imports to consumers. CFi ------- APPENDIX 66 TABLE 9 LIST OF MERCHANDISERS AND CONSUMERS OF SELENIUM AND ITS COMPOUNDS116 Accurate Electronics Co. Alliance Industrial Products Co. Allied International Co. Allis-Chalmers Manufacturing Co. Alloy chem Inc. Alloys Unlimited Inc. American Metal Climax Inc. American-Orient Products Corp. American Rectifier Corp. American Smelting and Refining Co. Amplex Chemical Co. Inc. Anaconda Sales Company Anchor Alloy Inc. Anglo-American Metal & Ferro Alloy Corp. Atomergic Chemicals Co. B & B Engineering Corp. B & B Motor and Control Corp. J. T. Baker .Chemical Co. Belmont Smelting and Refining Works Inc. Bogue Electric Manufacturing Co. Bradley Laboratories Inc. Bradley Semiconductor Corp. Cadillac Electric Products Ceramic Color and Chemical Manufacturing Co. Christie Electric Corp. City Chemical Corp. Clinton Supply Co. Inc. Darby Co. Ltd. Davidson Aluminum & Metal Corp. B. F. Drakenfield & Co. E. I. du Pont de Nemours & Co. Inc. Baling Corporation Edal Industries, Inc. Electron Equipment Corp. Electronic Devices Inc. Electronic Devices Inc. Electronic Rectifier Co. Inc. Electro-Seal Corp. Electronic Space Products Fansteel Metallurgical Corp. Franklin Fibre-Lamitex Corp. Gates Electronic Co. Inc. Chicago, 111. Chicago, 111. New York, N.Y. Milwaukee, Wis. New York, N.Y. Long Island City, N.Y. New York, N.Y. Rochester, N.Y. College Point, N.Y. New York, N.Y. New York, N.Y. New York, N.Y. Brooklyn, N.Y. New York, N.Y. Carle Place, N.Y. Norwood, La. New York, N.Y. North Phillipsburg, N.J. Brooklyn, N.Y. Paterson, N.J. New Haven, Conn. New Haven, Conn. New Rochelle, N.Y. New Brighton, Pa. Los Angeles, Calif. New York, N.Y. Chicago, 111. Pittsburgh, Pa. Brooklyn, N.Y. New York, N.Y. Wilmington, Del. Cambridge, Mass. East Haven, Conn. South Pasadena, Calif. Brooklyn, N.Y. Yonkers, N.Y. Rochester, N.Y. Des Plaines, 111. Los Angeles, Calif. North Chicago, 111. Wilmington, Del. Bronx, N.Y. (continued) ------- 67 APPENDIX TABLE 9 LIST OF MERCHANDISERS AND CONSUMERS OF SELENIUM AND ITS COMPOUNDS116 General Electric Co. General Instrument Corp. Green Electric Co. Inc. Industrial Metals Improvement Co. Industrial Rectifier Co. Insulation Products Co. International Rectifier Corp. IRC Inc., Boone Div. ITT Components Div. Kawecki Chemical Co. Inc. Kennecott Sales Corp. Kneisley Electric Co. La Marche Bros. Lambda Electronics Corp. Ledex Div., Ledex Inc. Lorain Products Corp. Macarr Inc. McKesson & Robbins, Inc. Meaker Co. Meaker Co. Mellaphone Corp. Metallurgical Products Co. Metropolitan Metal Co. Miller Sanford Corp. Model Rectifier Corp. Ohio Semiconductors Division Opad Electric Co. Inc. Pancoast International Corp. Phelps Dodge Refining Corp. Power Designs Inc. Radio Receptor Co. Inc. Ramm Rectifier Co. Inc. Ramyr Manufacturing Co. Rapid Electric Co. Inc. Rectico Inc. Rectifier Engineering & Supply Co. Republic Chemical Corp. J. E. Robin Inc. J. A. Samuel & Co. Sarkes Tarzian Inc. Schauer Manufacturing Co. Semi Alloys Inc. Seneca Electric Co. Siegel Chemical Co. Inc. Strong Electric Corp. Schenectady, N.Y. Hicksville, L.I., N.Y. Fair Lawn, N.J. Pittsburgh, Pa. New York, N.Y. Pittsburgh, Pa. El Segundo, Calif. Boone, N.C. Clifton, N.J. New York, N.Y. New York, N.Y. Toledo, Ohio Chicago, 111. Plainview, N.Y. Dayton, Ohio Lorain, Ohio New York, N.Y. New York, N.Y. Chicago, 111. Nut ley, N.J. Rochester, N.Y. Philadelphia, Pa. Detroit, Mich. Brooklyn, Brooklyn , Columbus, New York, New York, New York, Westbury, N.Y. N.Y. Ohio N.Y. N.Y. N.Y. N.Y. New York, N.Y. New York, N.Y. Los Angeles, Calif. Bronx, N.Y. Cedar Grove, N.J. St. Louis, Mo. New York, N.Y. East Orange, N.J. New York, N.Y. Bloomington, Ind. Cincinnati, Ohio Mt. Vernon, N.Y. Detroit, Mich. Brooklyn, N.Y. Toledo, Ohio (continued) ------- 68 APPENDIX TABLE 9 LIST OF MERCHANDISERS AND CONSUMERS OF SELENIUM AND ITS COMPOUNDS116 Sylvan Chemical Corp. Syntron Co. Technical Apparatus Builders C. Tennant Sons & Co. Inc. Ther Electric & Machine Works Inc. Trojan Rectifier and Equipment Co, United Mineral & Chemical Corp. R. T. Vanderbilt Co. Inc. Westinghouse Electric Corp. Zenitherm Alloys Corp. Max Zuckerman & Sons Englewood Cliffs, Homer City, Pa. New York, N.Y. New York, N.Y. Chicago, 111. Inc. Lancaster, N.Y. New York, N.Y. New York, N.Y. Pittsburgh, Pa. Elizabeth, N.J. Owings Mills, Md. N.J, ------- APPENDIX TABLE 10 PROPERTIES, TOXICITY, AND USES OF SOME SELENIUM COMPOUNDS 75 Compound Properties Toxicity Uses Aluminum selenide Al2Se3 Decomposes in water May be irritating to eyes, mucous membranes. Causes garlic odor of breath^ dizziness, nausea In preparation of hydrogen selenide; in semiconductor research Ammonium hydroselenate NH„(HSeO ) 4 4 Ammonium magnesium selenate Mg(NH4)Ss04 Decomposes Ammonium selenate (NH4)2Se03 Decomposes Ammonium selenite Decomposed by heat Occupational exposure has caused pallor, nervousness, depression, garlic odor of breath, gastrointestinal disturbances, and dermatitis In manufacture of red glass as reagent for alkaloids Antimony triselenide o. mp 605 C Occupational exposure has caused pallor, nervousness, depression, garlic odor of breath, G.I. disturbances, and dermatitis (continued) ------- APPENDIX TABLE 1.0 PROPERTIES, TOXICITY, AND USES OF SOME SELENIUM COMPOUNDS (Continued) Compound Arsenic hemiselenide As2Se Arsenic pentaselenide As2Se5 Arsenic triselenide As2Se3 Beryllium selenate BeSeO^, 4 Bismuth selenide Bi2Se3 Properties Decomposes in boiling alkali hydroxide Decomposes when heated in air mp 260°C mp 170UC Toxicity Highly toxic. Causes pallor, nervousness , depression, garlic odor of breath and sweat, and G.I. disturbances Highly toxic. Causes pallor, nervousness, depression, garlic odor of breath and sweat, and G.I. disturbances Highly toxic. Causes pallor, nervousness, depression, garlic odor of breath and sweat, and G.I. disturbances Death may result from short exposure to incredibly low concentrations of element and its salts Uses In manufacture of glass In semiconductor research (continued) ------- APPENDIX TABLE 10 PROPERTIES, TOXICITY, AND USES OF SOME SELENIUM COMPOUNDS (Continued) Compound Cadmium selenate CdSe04 Cadmium selenide CdSe Calcium selenide CaSe Cesium selenate Cs2Se04 Chloroselenic acid HClSe03 Cupric hydroselenite Cu(HSe03)2 Cupric selenate CuSeO 4 Cupric selenide CuSe Cupric selenite CuSeO-, Gold selenate Au2(Se04)3 Properties Decomposes at 100°C mp 1350°C mp 46°C Decomposes in light Toxicity Low toxic ity because of insolubility Uses In photoconductors, semiconductors , photoelectric cells, and rectifiers; in phosphors In electron emitters In coloring Cu or Cu alloys black As catalyst in Kjeldahl digestions; in semiconductors (continued) ------- APPENDIX TABLE 1Q PROPERTIES, TOXICITY, AND USES OF SOME SELENIUM COMPOUNDS (Continued) Compound Gold selenide Au2Se3 Hydrogen selenide H Se 2 Indium selenide InSe Lead selenate PbSeO4 Lead selenite PbSeO3 Lithium selenate LiSeO4 Lithium selenite LiSe03 Manganese selenate MnSeO4 • 2H O Manganese selenide MnSe Manganese selenite MnSeO3'2H2O Properties Decomposed by heat mp -64°C mp 660°C Decomposes Melts at about 500 C Toxicity May be irritating to eyes, mucous membranes. Causes garlic odor of breath, dizziness, nausea Uses In semiconductor research to (continued) ------- APPENDIX TABLE 10 PROPERTIES, TOXICITY, AND USES OF SOME SELENIUM COMPOUNDS (Continued) Compound Properties Toxicity Uses Phosphorus pentaselenide Decomposes Phosphorus triselenide P4Se3 mp 242 C Potassium biselenite Potassium cobaltus selenate K2Co(Se04)2 Potassium selenate As reagent Potassium selenide K2Se Rubidium selenate Selenic acid H2SeO4 bp 26 (PC mp 58°C Selenium bromide Decomposes at 227°C mp -46°C Occupational exposure has caused pallor, nervousness, depression, garlic odor of breath, G.I. disturbances, and dermatitis (continued) ------- APPENDIX TABLE 10 PROPERTIES, TOXICITY, AND USES OF SOME SELENIUM COMPOUNDS (Continued) Compound Properties Toxicity Uses Selenium chloride Se2Cl2 Decomposes at 100°C bp 130°C mp -85°C Can cause pallor, nervousness, depression, garlic odor of breath, depression, G.I. disturbances, and dermatitis Selenium disulfide SeS_ mp 100UC Occupational exposure has caused pallor, nervousness, depression, garlic odor of breath, G.I. disturbances, and dermatitis In eczemas and fungus infections in dogs and cats Selenium hexafluoride mp -39UC bp -34.5°C sublimes at -46.6°C Occupational exposure has caused pallor, nervousness, depression, garlic odor of breath, G.I. disturbances, and dermatitis As gaseous electric insulator Selenium monosulfide SeS Decomposes at 118-9DC Occupational exposure has caused pallor, nervousness, depression, garlic odor of breath and sweat, G.I. disturbances, and dermatitis Vet use: topically against eczemas, fungus infections, demodectic mange, flea bites in small animals (continued) ------- APPENDIX TABLE 10 PROPERTIES, TOXICITY, AND USES OF SOME SELENIUM COMPOUNDS (Continued) Compound Properties Toxicity Uses Selenium oxide '2 mp 340 C Occupational exposure has caused pallor, nervousness, depression, garlic odor of breath and sweat, G.I. disturbances, and dermatitis In the manufacture of other selenium compounds; as a reagent for alkaloids Selenium oxychloride SeOCl0 top 180 C Strong irritant, vesicant. Can cause fatal pulmonary edema Selenium oxyfluoride l 2 bp 124QC mp 4.6 C Strong irritant, vesicant. Can cause fatal pulmonary edema Selenium tetrabromide Decomposes at 70-80°C Occupational exposure has caused pallor, nervousness, depression, garlic odor of breath, G.I. disturbances, and dermatitis Selenium tetrachloride SeCl, mp 305 C Sublimes at 170-196 C Can cause pallor, nervousness, depression, garlic odor of breath, G.I. disturbances, and dermatitis Silver selenide Ag2Se mp 880 C (continued) ------- APPENDIX TABLE 10 PROPERTIES, TOXICITY, AND USES OF SOME SELENIUM COMPOUNDS (Continued) Compound Silver selenite Ag SeO 2 3 Sodium hydroselenite NaHSeO3 Sodium selenate Na2SeO4 Sodium selenide Na2Se Sodium selenite Na2Se°3 Stannic selenide SnSe2 Stannic selenite Sn(Se03)2 Stannous selenide SnSe Strontium selenate SrSeO Properties Decomposed by heat to selenium oxide mp 875°C mp 650°C mp 861°C Toxicity Uses As insecticide in some horticultural applications In removing green color from glass during its manufacture as alkaloidal reagent (continued) ------- APPENDIX TABLE 10 PROPERTIES, TOXICITY, AND USES OF SOME SELENIUM COMPOUNDS (Continued) Compound Properties Toxicity Uses Strontium selenide SrSe Thallium selenate Tl SeO,. mp 400 C Thallium selenide mp 340°C Zinc selenate ZnSeO. mp 50 C Decomposes Zinc selenide ZnSe o, mp HOO^C Occupational exposure has caused pallor, nervousness, depression, garlic odor of breath, G.I. disturbances, and dermatitis ------- APPENDIX 78 TABLE 11 SELENIUM CONTENT OF DUST FROM AIR-CONDITIONING FILTERS, 1941 66 Type of Building Where Sample Was Collected Location Se (ppm) Industrial Dry goods store Industrial Residence Residence Residence Office building Unknown Residence Unknown Office building Los Angeles, Calif. 0.8 San Francisco, Calif. 0.05 San Francisco, Calif. 0.6 Grand Forks, N.Dak. 6 Houston, Tex. 3 University City, Mo. 2.5 (suburb of St. Louis) St. Louis, Mo. 10 Chicago, 111. 2.5 Shaker Heights, Ohio 2.5 (suburb of Cleveland) Philadelphia, Pa. 1.5 Washington, D.C. 5 ------- |