Selenium

H301: Toxic if swallowed [Danger Acute toxicity, oral]

H331: Toxic if inhaled [Danger Acute toxicity, inhalation]

H373 **: May causes damage to organs through prolonged or repeated exposure [Warning Specific target organ toxicity, repeated exposure]

H413: May cause long lasting harmful effects to aquatic life [Hazardous to the aquatic environment, long-term hazard]

P260, P261, P264, P270, P271, P273, P301+P316, P304+P340, P316, P319, P321, P330, P403+P233, P405, and P501 (click each P-code to see the statement)

H301+H331 (27.4%): Toxic if swallowed or if inhaled [Danger Acute toxicity, oral; acute toxicity, inhalation]

H301 (100%): Toxic if swallowed [Danger Acute toxicity, oral]

H331 (99.8%): Toxic if inhaled [Danger Acute toxicity, inhalation]

H373 (99.7%): May causes damage to organs through prolonged or repeated exposure [Warning Specific target organ toxicity, repeated exposure]

H413 (95.8%): May cause long lasting harmful effects to aquatic life [Hazardous to the aquatic environment, long-term hazard]

Aggregated GHS information provided per 1063 reports by companies from 29 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Information may vary between notifications depending on impurities, additives, and other factors. The percentage value in parenthesis indicates the notified classification ratio from companies that provide hazard codes. Only hazard codes with percentage values above 10% are shown. For more detailed information, please visit ECHA C&L website.

H370: Causes damage to organs [Danger Specific target organ toxicity, single exposure]

H372: Causes damage to organs through prolonged or repeated exposure [Danger Specific target organ toxicity, repeated exposure]

P260, P264, P270, P308+P316, P319, P321, P405, and P501 (click each P-code to see the statement)

H361: Suspected of damaging fertility or the unborn child [Warning Reproductive toxicity]

P203, P260, P264, P270, P280, P308+P316, P318, P321, P405, and P501 (click each P-code to see the statement)

H373: May causes damage to organs through prolonged or repeated exposure [Warning Specific target organ toxicity, repeated exposure]

Fresh air, rest. Refer for medical attention.

Rinse and then wash skin with water and soap.

Rinse with plenty of water (remove contact lenses if easily possible).

Rinse mouth. Refer for medical attention .

Excerpt from NIOSH Pocket Guide for Selenium:

Eye: IRRIGATE IMMEDIATELY - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately.

Skin: SOAP WASH IMMEDIATELY - If this chemical contacts the skin, immediately wash the contaminated skin with soap and water. If this chemical penetrates the clothing, immediately remove the clothing, wash the skin with soap and water, and get medical attention promptly.

Breathing: RESPIRATORY SUPPORT - If a person breathes large amounts of this chemical, move the exposed person to fresh air at once. If breathing has stopped, perform artificial respiration. Keep the affected person warm and at rest. Get medical attention as soon as possible.

Swallow: MEDICAL ATTENTION IMMEDIATELY - If this chemical has been swallowed, get medical attention immediately. (NIOSH, 2024)

(General first aid procedures)

Eye: Irrigate immediately - If this chemical contacts the eyes, immediately wash (irrigate) the eyes with large amounts of water, occasionally lifting the lower and upper lids. Get medical attention immediately.

Skin: Soap wash immediately - If this chemical contacts the skin, immediately wash the contaminated skin with soap and water. If this chemical penetrates the clothing, immediately remove the clothing, wash the skin with soap and water, and get medical attention promptly.

Breathing: Respiratory support

Swallow: Medical attention immediately - If this chemical has been swallowed, get medical attention immediately.

Excerpt from ERG Guide 151 [Substances - Toxic (Non-Combustible)]:

SMALL FIRE: Dry chemical, CO2 or water spray.

LARGE FIRE: Water spray, fog or regular foam. If it can be done safely, move undamaged containers away from the area around the fire. Dike runoff from fire control for later disposal. Avoid aiming straight or solid streams directly onto the product.

FIRE INVOLVING TANKS, RAIL TANK CARS OR HIGHWAY TANKS: Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles. Do not get water inside containers. Cool containers with flooding quantities of water until well after fire is out. Withdraw immediately in case of rising sound from venting safety devices or discoloration of tank. ALWAYS stay away from tanks in direct contact with flames. For massive fire, use unmanned master stream devices or monitor nozzles; if this is impossible, withdraw from area and let fire burn. (ERG, 2024)

Use foam, powder, carbon dioxide. NO water.

Extinguishant: For selenium, water

If material on fire or involved in fire: Extinguish fire using agent suitable for type of surrounding fire. Material itself does not burn or burns with difficulty. Keep run-off water out of sewers and water sources. /Selenium compound, solid, nos/

Personnel protection: Wear appropriate chemical protective clothing. Wear positive pressure self-contained breathing apparatus when fighting fires involving this material. /Selenium compound, solid, nos/

Excerpt from ERG Guide 151 [Substances - Toxic (Non-Combustible)]:

IMMEDIATE PRECAUTIONARY MEASURE: Isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids.

SPILL: Increase the immediate precautionary measure distance, in the downwind direction, as necessary.

FIRE: If tank, rail tank car or highway tank is involved in a fire, ISOLATE for 800 meters (1/2 mile) in all directions; also, consider initial evacuation for 800 meters (1/2 mile) in all directions. (ERG, 2024)

Personal protection: particulate filter respirator adapted to the airborne concentration of the substance. Do NOT let this chemical enter the environment. Sweep spilled substance into covered containers. If appropriate, moisten first to prevent dusting. Carefully collect remainder. Then store and dispose of according to local regulations.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

Persons not wearing protective equipment and clothing should be restricted from areas of spills until cleanup has been completed. /Selenium and its inorganic cmpd/

If selenium or its inorganic compounds are spilled, the following steps should be taken: 1. Ventilate area of spill. 2. Collect spilled material in the most convenient and safe manner and deposit in sealed containers for reclamation or for disposal in a secured sanitary landfill. Liquid containing selenium and its inorganic compounds should be absorbed in vermiculite, dry sand, earth, or a similar material. Waste disposal method: Selenium and its inorganic compounds may be disposed of in sealed containers in a secured sanitary landfill. /Selenium and its inorganic cmpd/

Environmental considersations: Land spill: Cover solids with a plastic sheet to prevent dissolving in rain or fire fighting water. Dike surface flow using soil, sand bags, foamed polyurethane, or foamed concrete. /Selenium compound, solid, nos/

Environmental considerations: Water spill: Use natural barriers or oil spill control booms to limit spill travel. Use natural deep water pockets, excavated lagoons, or sand bag barriers to trap material at bottom. Use mechanical dredges or lifts to remove immobilized masses of pollutants and precipitates. /Selenium compound, solid, nos/

Generators of waste (equal to or greater than 100 kg/mo) containing this contaminant, EPA hazardous waste number D010, must conform with USEPA regulations in storage, transportation, treatment and disposal of waste.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

... As the price of selenium is very high; recovery of it by processing selenium containing waste is economical. For example, selenium refineries are equipped with wet scrubbers that employ an approx 50% soln of hydrobromic acid containing free bromine. The acid fumes are adsorbed in a lime and soda bed, and the selenium separated from the hydrobromic acid soln by distilliation is recycled. ... If possible, convert selenium compounds to an insoluble form with SO2 before landfill or solidification. Do not use metal and acid to reduce selenium compounds. This will produce toxic gaseous hydrogen selenide.

Depending upon the industrial source, selenium occurs in either the particulate or the soluble form. For the former, physical treatment processes such as sedimentation or filtration are quite effective. Lime precipitation of soluble selenium has been shown to be ineffective. Alum coagulation/coprecipitation is somewhat effective, with removal efficiencies approaching 50% achievable. Iron coagulation/coprecipitation is capable of above 80% selenium removal, with efficiency increasing with decreasing pH. Activated carbon adsorption is not effective, except in one reported instance involving high pH pretreatment. The most efficient process for soluble selenium appears to be anion exchange. Preoxidation of the selenite to selenate is reported to enhance exchange capacity. /Selenium compounds/

For more Disposal Methods (Complete) data for SELENIUM COMPOUNDS (7 total), please visit the HSDB record page.

Smoking, eating and drinking at the workplace should be prohibited and messrooms and sanitary facilities including showers and locker rooms should be provided at a point distant from exposure areas.

Where there is any possibility of exposure of an employee's body to selenium, selenium oxychloride, sodium selenite, sodium selenate, selenium dioxide, or liquids containing these compounds, facilities for quick drenching of the body should be provided within the immediate work area for emergency use.

Employees should be provided with and required to use impervious clothing, gloves, face shields (eight inch minimum), and other appropriate protective clothing necessary to prevent repeated or prolonged skin contact with selenium, sodium selenite, or sodium selenate.

Non-impervious clothing which becomes contaminated with selenium, sodium selenite, sodium selenate, selenium dioxide or liquids containing these compounds should be removed promptly and not reworn until the contaminant is removed from the clothing.

For more Preventive Measures (Complete) data for SELENIUM, ELEMENTAL (12 total), please visit the HSDB record page.

If the concentration of selenium in the urine of workers on a particular process is above 0.1 mg/L then action should be taken to improve the industrial hygiene of that process. /Selenium compounds/

Where there is any possibility of exposure of an employee's body to selenium, selenium oxychloride, sodium selenite, sodium selenate, selenium dioxide, or liquids containing these compounds, facilities for quick drenching of the body should be provided within the immediate work area for emergency use. /Selenium and its inorganic salts/

Non-impervious clothing which becomes contaminated with selenium, sodium selenite, sodium selenate, selenium dioxide or liquids containing these compounds should be removed promptly and not reworn until the contaminant is removed from the clothing. /Selenium and its inorganic salts/

Eye Exposure: If selenium or its inorganic compounds get into the eyes, wash eyes immediately with large amounts of water, lifting the lower and upper lids occasionally. Get medical attention immediately. /Selenium and its inorganic salts/

For more Preventive Measures (Complete) data for SELENIUM COMPOUNDS (10 total), please visit the HSDB record page.

Excerpt from ERG Guide 151 [Substances - Toxic (Non-Combustible)]:

Do not touch damaged containers or spilled material unless wearing appropriate protective clothing. Stop leak if you can do it without risk. Prevent entry into waterways, sewers, basements or confined areas. Cover with plastic sheet to prevent spreading. Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers. DO NOT GET WATER INSIDE CONTAINERS. For solids, prevent dust cloud and avoid inhalation of dust. (ERG, 2024)

Separated from strong oxidants, strong acids and food and feedstuffs. Dry. Store in an area without drain or sewer access. Provision to contain effluent from fire extinguishing.

Usually stored at room temperature. Precautions must be taken to avoid contact with water or prolonged exposure to air and other materials with which it may react. Storage area construction must be such that rain water will not leak in or ground water will not enter. Used drums should be stored in this same dry area to avoid contamination /SRP: of the area/ and to minimize any hazard due to the residues.

TIH (Toxic Inhalation Hazard) - Term used to describe gases and volatile liquids that are toxic when inhaled. Some are TIH materials themselves, e.g., chlorine, and some release TIH gases when spilled in water, e.g., chlorosilanes. [ERG 2016].

0.02 [mg/m3], as Se, inhalable fraction (metal and inorganic compds)[German Research Foundation (DFG)]

0.60 [mg/m3]

17 [mg/m3]

100 [mg/m3]

0.2 mg/m³

TWA 0.2 mg/m3 [*Note: The REL also applies to other selenium compounds (as Se) except Selenium hexafluoride.]

0.2 [mg/m3], as Se (compds.)

TWA 0.2 mg/m3 [*Note: The PEL also applies to other selenium compounds (as Se) except Selenium hexafluoride.]

1 mg Se/m3 (NIOSH, 2024)

1.0 [mg/m3], as Se

Excerpts from Documentation for IDLHs: The revised IDLH for selenium compounds is 1 mg Se/m3 based on acute toxicity data in animals [Olson 1986; Pletnikova 1970a, 1970b]. This may be a conservative value for selenium compounds in general since it is based on sodium selenite, which is orders of magnitude more toxic than many other selenium compounds. Further, this may also be a conservative value due to the lack of relevant acute toxicity data for workers.

1 mg/cu m (as Se)

1 mg/cu m (as Se) /Selenium/

1 mg/m3 (as Se)

See: 7782492

0.2 [mg/m3], as Se (metal and compds)

8 hr Time Weighted Avg (TWA): 0.2 mg/cu m. /Selenium and compounds, as Se/

Excursion Limit Recommendation: Excursions in worker exposure levels may exceed 3 times the TLV-TWA for no more than a total of 30 minutes during a work day, and under no circumstances should they exceed 5 times the TLV-TWA, provided that the TLV-TWA is not exceeded. /Selenium and compounds, as Se/

0.2 mg/m

0.2 mg/m³ [1992]

(inhalable fraction): 0.02 mg/m

Chronic Oral: 0.005 mg/kg/day (L134)

Australia: 0.2 mg/cu m, as Se (selenium compounds, excluding hydrogen selenide) (1990); Federal Republic of Germany: 0.1 mg/cu m, as Se total dust, short-term level 1.0 mg/cu m, 30 minutes, once per shift (1991); Sweden: 0.1 mg/cu m, as Se (selenium and inorganic compounds, except hydrogen selenide) (1990); United Kingdom: 0.1 mg/cu m, as Se (selenium and cmpounds, except hydrogen selenide) (1991).

A harmful concentration of airborne particles can be reached quickly on spraying or when dispersed, especially if powdered.

The substance is irritating to the respiratory tract. The substance may cause effects on the gastrointestinal tract and nervous system.

The substance may have effects on the respiratory tract, gastrointestinal tract and skin.

Selenium Decay Pathways

Table: Natural Isotopes [Table#4965]

Table: Artificial Isotopes [Table#4966]

ALI values have been established for individual radionuclides and are presented in Table 1 in Appendix B to PART 20.1001-20.2401. The ALI values for inhalation, presented in Column 2 in Table 1, correspond to a committed effective dose equivalent of 5 rems (0.05 Sv) or a committed dose equivalent of 50 rems (0.5 Sv) to any individual organ or tissue, whichever is more limiting. If the ALI value presented in Table 1 is limited by the 50-rem committed dose equivalent, the controlling organ is listed directly below the ALI value, and the stochastic ALI value based on the 5-rem committed effective dose equivalent is listed ... directly below the organ name. If a stochastic ALI is listed in parentheses, that value should be used to calculate the committed effective dose equivalent.

OCCUPATIONAL VALUES FOR SELENIUM (Class W, oxides, hydroxides, carbides, and elemental Se. Class D, all compounds except those given for W) [Table#4967]

For more Radiation Limits and Potential (Complete) data for SELENIUM, ELEMENTAL (6 total), please visit the HSDB record page.

OCCUPATIONAL VALUES FOR SELENIUM (Class W, oxides, hydroxides, carbides, and elemental Se. Class D, all compounds except those given for W) [Table#6425]

EFFLUENT CONCENTRATIONS ESTABLISHED BY THE NRC FOR SOME SELENIUM COMPOUNDS [Table#6426]

QUANTITIES OF NRC LICENSED MATERIAL REQUIRING LABELING [Table#6427]

Excerpt from NIOSH Pocket Guide for Selenium:

Skin: PREVENT SKIN CONTACT - Wear appropriate personal protective clothing to prevent skin contact.

Eyes: No recommendation is made specifying the need for eye protection.

Wash skin: WHEN CONTAMINATED - The worker should immediately wash the skin when it becomes contaminated.

Selenium is a reddish colored powder that may become black upon exposure to air. It is toxic by ingestion. It is used to manufacture electronic components and rubber.

Dry Powder; Other Solid; CBI

Amorphous or crystalline, red to gray solid; Note: Occurs as an impurity in most sulfide ores; [NIOSH]

GREY SOLID IN VARIOUS FORMS.

Amorphous or crystalline, red to gray solid.

Amorphous or crystalline, red to gray solid. [Note: Occurs as an impurity in most sulfide ores.]

Selenium exists in several allotropic forms. 3 are generally recognized ... Selenium can be prepd with either amorphous or crystalline structure. ... Amorphous is either red, in powder form or black, in vitreous form. Crystalline monoclinic selenium is deep red; crystalline hexagonal form, the most stable variety, is a metallic gray.

1265 °F at 760 mmHg (NIOSH, 2024)

685 °C @760 [mm Hg]

392 °F (NIOSH, 2024)

220.8 °C (gray selenium); vitreous selenium is transformed to gray selenium at 180 °C; alpha-form transforms to gray at temperatures above 120 °C

220.8 °C

Insoluble (NIOSH, 2024)

Insoluble

Soluble in aq potassium cyanide soln, potassium sulfite soln, dilute aqueous caustic alkali soln

Insoluble in water and alcohol

Soluble in concentrated nitric acid.

Soluble in carbon disulfide, 2 mg/100 mL at room temperature; soluble in ether

Solubility in water: none

4.28 (NIOSH, 2024) - Denser than water; will sink

4.39 g/cu cm (alpha form); 4.809 g/cu cm (gray selenium); 4.28 g/cu cm (vitreous selenium)

Vitreous, Black selenium; dark red-brown to bluish-black solid; density = 4.28; softens at 50 to 60 °C and becomes elastic at 70 °C. Red amorphous form; density = 4.26. When freshly precipitated, reacts with water at 50 °C forming selenious acid and hydrogen. Soluble in carbon disulfide, methylene iodide, benzene or quinoline /amorphous forms/

Relative density (water = 1): 4.8

4.809 @25 °C

0 mmHg (approx) (NIOSH, 2024)

1 Pa at 227 °C; 10 Pa at 279 °C; 100 Pa at 344 °C; 1 kPa at 431 °C; 10 kPa at 540 °C; 100 kPa at 685 °C

Vapor pressure, Pa at 20 °C: 0.1

0 mmHg (approx)

When heated to decomp ... emits toxic fumes of /selenium/.

221 mPa-S (= cP) at 220 °C; 70 cP at 360 °C

Strongly corrosive, especially at high temperature.

-225.1 kJ/mol at 298 K

59.7 kJ/mol

105.5 dyn/cm at 220 °C; 95.2 dyn/cm at 310 °C (liquid)

Combines directly with hydrogen, with the halogens (excluding iodine); oxidized to selenious acid by nitric acid, to selenic acid by sulfuric acid; reduces hot aqueous soln of silver and gold salts with formation of silver selenide and metallic gold, respectively

Exhibits both photovoltaic action, where light is converted directly to electricity; exhibits photoconductive action, where electrical resistance decreases with increased illumination

Two monoclinic forms; dark red, transparent crystals. Melting point below 200 °C. Density (alpha-form) 4.46. Both forms are metastable and change into gray form on heating /Crystalline or red selenium/.

Crystalline selenium is a p-type semiconductor... forms binary alloys with silver, copper, zinc, lead, etc.

Selenium reacts with electropositive elements (many metals) to form selenides.

Liquid is a brownish red

Insoluble in water.

Metals, Elemental and Powder, Active

Strong Reducing Agent

SELENIUM, silicon, or sulfur ignites in fluorine gas at ordinary temperatures [Mellor 2:11-13 1946-47]. A mixture of barium carbide and selenium heated to 150 °C becomes incandescence [Mellor 5:862 1946-47]. Calcium carbide and selenium vapor react with incandescence [Mellor 5:862 1946-47]. A moist mixture of selenium and chlorates, except the alkali chlorates, becomes incandescent. Selenium reacts violently with chromium trioxide [Mellor 11:233 1946-47]. Reaction of selenium and silver bromate (also potassium bromate) is violently explosive [Mellor 2, Supp1:763 1956]. Freshly reduced selenium reacts vigorously with nitric acid. Trace amounts of organic matter probably influenced the reaction [J. Chem. Soc. 1938 p.391]. The reaction between zinc and selenium or tellurium is accompanied by incandescence [Mellor 4:476-480 1946-47].

Selenium + Silver bromate: The reaction is violently explosive.

Freshly reduced selenium (from selenium dioxide) reacts vigorusly with nitric acid. Trace of organic matter probably influlenced the reaction.

Reacts violently with chromium trioxide.

Can react violently with ... chromic oxide (CrO3), ... lithium silicon (Li6Si2), ... nitric acid, ... nitrogen trichloride, oxygen, ... potassium bromate, ... silver bromate. ...

For more Hazardous Reactivities and Incompatibilities (Complete) data for SELENIUM, ELEMENTAL (22 total), please visit the HSDB record page.

Do not use metal and acid to reduce selenium compounds. This will produce toxic gaseous hydrogen selenide.

Acids, strong oxidizers, chromium trioxide, potassium bromate. /Selenium/

Acids, strong oxidizers, chromium trioxide, potassium bromate, cadmium

CDC-ATSDR Toxicological Profile

Selenium is an essential trace element and has been shown to be a natural component in the enzyme glutathione peroxidase and other proteins. Most selenium compounds are water-soluble and can efficiently be taken up in the intestine. Soluble as well as non-soluble compounds can be taken up by the lungs. When given in excess, selenium compounds are rapidly distributed to major organs of the body. ... Identified metabolites are trimethylselenide in urine and dimethylselenide in breath. ... in man ... toxic effects have been reported at 1 mg/dl. ... Toxic effects have been seen at blood levels ranging from 0.179 ug/ml-7.5 ug/ml. In most parts of the world normal urine levels do not exceed 0.03 ug/ml. Occupationally exposed workers usually excrete less than 0.1 ug/ml. The LD50 ranges between 1.5 and 6 mg/kg for many selenium compounds and animal species. The CNS seems to be the target organ ... but the liver, heart, and lungs may also be affected. A few cases of selenium poisoning in humans have been described ... either after consumption of selenium or after exposure via inhalation. Gastrointestinal and neurological symptoms predominated. Chronic poisoning due to long term exposure has been reported in livestock and humans from geographical areas where soil contains high levels of selenium. In rodent liver cirrhosis is a common effect while typical effects in domestic animals are: emaciation, deformation of hooves, loss of hair, and joint erosions. In humans consuming 5 mg selenium per day, hair and nail problems are very common. Skin lesions and depigmentation are also common signs of intoxication. In more severe cases neurological and gastrointestinal symptoms predominate. ... Several selenium compounds have been tested for possible carcinogenic potential. Selenium sulfide has been shown to induce liver cancer in two species while no convincing evidence of carcinogenicity has been presented for other selenium compounds. ... Some selenium compounds may induce DNA damage and some previous reports indicate a teratogenic potential ... . Selenium may prevent or alleviate toxic effects of arsenic, cadmium, mercury, platinum, and silver. Conversely, some of these metals protect against selenium toxicity.

Selenium is considered a relatively non-toxic supplement. However, extremely high selenium intake can result in diarrhea, fatigue, hair loss, joint pain, nail discoloration or brittleness, and nausea. Due to selenium supplementation toxicity being extremely rare, there is no current treatment for selenium overdose. If selenium toxicity is suspected, it is best to stop using the supplement.

Selenium readily substitutes for sulfur in biomolecules and in many biochemical reactions, especially when the concentration of selenium is high and the concentration of sulfur is low. Inactivation of the sulfhydryl enzymes necessary for oxidative reactions in cellular respiration, through effects on mitochondrial and microsomal electron transport, might contribute to acute selenium toxicity. Selenomethionine (a common organic selenium compound) also appears to randomly substitute for methionine in protein synthesis. This substitution may affect the structure and functionability of the protein, for example, by altering disulfide bridges. Inorganic forms of selenium appear to react with tissue thiols by redox catalysis, resulting in formation of reactive oxygen species and causing damage by oxidative stress. (L619)

Selenium and Compounds

Hematologic

5 x 10 ^-3 mg/kg-day

Selenium

Trace element

Smith, C.D. and Nowell, L.H., 2024. Health-Based Screening Levels for evaluating water-quality data (3rd ed.). DOI:10.5066/F71C1TWP

Cancer Classification: Group D Not Classifiable as to Human Carcinogenicity

CLASSIFICATION: D; not classifiable as to human carcinogenicity. BASIS FOR CLASSIFICATION: Based on inadequate human data and inadequate evidence of carcinogenicity in animals. The evidence for various selenium compounds in animal and mutagenicity studies is conflicting and difficult to interpret; however, evidence for selenium sulfide is sufficient for a B2 (probable human carcinogen) classification. HUMAN CARCINOGENICITY DATA: Inadequate. ANIMAL CARCINOGENICITY DATA: Inadequate.

Classification of carcinogenicity: 1) evidence in humans: inadequate; 2) evidence in animals: inadequate. Summary evaluation of carcinogenic risk to humans 3: The agent is not classifiable as to its carcinogenicity to humans. /From table, Selenium and selenium compounds/

CLASSIFICATION: D; not classifiable as to human carcinogenicity. BASIS FOR CLASSIFICATION: Based on inadequate human data and inadequate evidence of carcinogenicity in animals. The evidence for various selenium compounds in animal and mutagenicity studies is conflicting and difficult to interpret; however, evidence for selenium sulfide is sufficient for a B2 (probable human carcinogen) classification. HUMAN CARCINOGENICITY DATA: Inadequate. ANIMAL CARCINOGENICITY DATA: Inadequate. /Based on former classification system/

Selenium and selenium compounds

Group 3: Not classifiable as to its carcinogenicity to humans

Volume 9: (1975) Some Aziridines, N-, S- and O-Mustards and Selenium

Volume Sup 7: Overall Evaluations of Carcinogenicity: An Updating of IARC Monographs Volumes 1 to 42, 1987; 440 pages; ISBN 92-832-1411-0 (out of print)

3, not classifiable as to its carcinogenicity to humans. (L135)

Chronic oral exposure to high concentrations of selenium compounds can produce a disease called selenosis. The major signs of selenosis are hair loss, nail brittleness, and neurological abnormalities (such as numbness and other odd sensations in the extremities). Animal studies have shown that selenium may also affect sperm production and the female reproductive cycle. (L619)

The substance can be absorbed into the body by inhalation and by ingestion.

inhalation, ingestion, skin and/or eye contact

Oral(L619) ; inhalation (L619) ; dermal (L619).

Sore throat. Cough. Nasal discharge. Loss of smell. Headache.

Redness.

Garlic breath. Diarrhoea.

irritation eyes, skin, nose, throat; visual disturbance; headache; chills, fever; dyspnea (breathing difficulty), bronchitis; metallic taste, garlic breath, gastrointestinal disturbance; dermatitis; eye, skin burns; In Animals: anemia; liver necrosis, cirrhosis; kidney, spleen damage

Short-term oral exposure to high concentrations of selenium may cause nausea, vomiting, and diarrhea. Brief exposures to high levels of elemental selenium or selenium dioxide in air can result in respiratory tract irritation, bronchitis, difficulty breathing, and stomach pains. Longer-term exposure to either of these air-borne forms can cause respiratory irritation, bronchial spasms, and coughing. (L619)

Cardiovascular (Heart and Blood Vessels), Dermal (Skin), Gastrointestinal (Stomach and Intestines, part of the digestive system), Hepatic (Liver), Neurological (Nervous System), Renal (Urinary System or Kidneys), Respiratory (From the Nose to the Lungs)

Eyes, skin, respiratory system, liver, kidneys, blood, spleen

Neurotoxin - Other CNS neurotoxin

Occupational hepatotoxin - Secondary hepatotoxins: the potential for toxic effect in the occupational setting is based on cases of poisoning by human ingestion or animal experimentation.

Reproductive Toxin - A chemical that is toxic to the reproductive system, including defects in the progeny and injury to male or female reproductive function. Reproductive toxicity includes developmental effects. See Guidelines for Reproductive Toxicity Risk Assessment.

Toxic Pneumonitis - Inflammation of the lungs induced by inhalation of metal fumes or toxic gases and vapors.

Selenium supplementation has a very low adverse effect profile. Most adverse reactions center on selenium sulfide. The more common adverse effects include redness, burning, itching, stinging, scalp sores, increased oiliness, nail hyperpigmentation, and skin irritation, creating contact dermatitis. Less common effects associated specifically with selenium sulfide shampoo include scalp hyperpigmentation, scalp discoloration, and alopecia. A rare non-dermatologic effect includes nausea due to the odor of the medication. There are no reported severe reactions to using this drug.

Assuming a human body wt of 70 kg, the acceptable daily intake for selenium is 0.002 mg/day. /Selenium/

IRIS Current

HEAST Current

LCLo (rat) = 33 mg/m3/8 hr

LD50: 6700 mg/kg (Oral, Rat) (T14)

LC50 Tanytarsus dissimilis (Chironomid) 42,400 ppb/96 hr /Selenium salts/

LC50 Apeltes quadracus (Fourspine sickleback) 17,350 ppb/96 hr /Selenium salts/

LC50 Lagodon rhomboides (Pinfish) 4400 ppb/96 hr /Selenium salts/

LC50 Melanogrammus aeglefinus (Haddock, larvae) 600 ppb/96 hr /Selenium salts/

For more Ecotoxicity Values (Complete) data for SELENIUM COMPOUNDS (34 total), please visit the HSDB record page.

/AQUATIC SPECIES/ ... Toxicities of selenium particles at nano-size (Nano-Se) and selenite in selenium-sufficient Medaka (Oryzias latipes) fish were compared. Selenium bioaccumulation and subsequent clearance in fish livers, gills, muscles and whole bodies were examined after 10 days of exposure to Nano-Se and selenite (100 microg Se/L) and again after 7 days of depuration. Both forms of selenium exposure effectively increased selenium concentrations in the investigated tissues. Surprisingly, Nano-Se was found to be more hyper-accumulated in the liver compared to selenite with differences as high as sixfold. Selenium clearance of both Nano-Se and selenite occurred at similar ratios in whole bodies and muscles but was not rapidly cleared from livers and gills. Nano-Se exhibited strong toxicity for Medaka with an approximately fivefold difference in terms of LC(50) compared to selenite. Nano-Se also caused larger effects on oxidative stress, most likely due to more hyper-accumulation of selenium in liver...

/BIRDS and MAMMALS/ Birds ... may be affected with chronic selenium toxicosis. Eggs with >2.5 ppm selenium from birds in high selenium areas have low hatchability, and the embryos are usually deformed. Teratologic effects include underdeveloped feet and legs, malformed eyes, crooked beaks, and ropy feathers. This has been a problem with waterfowl in southern California, where selenium was leached by agricultural water and concentrated in lakes by runoff. /Selenium/

/BIRDS and MAMMALS/ Combined lesser scaup (Aythya affinis) and greater scaup (A. marila) populations decreased from the 1980s to the 1990s and have not recovered. /This study/ examined the effects of cadmium, mercury, selenium, and corticosterone on pair status and on male reproductive indices ... in male lesser scaup collected in the western boreal forest near Yellowknife, Northwest Territories, May and June, during 2004 and 2005. Male scaup that were larger in size (p = 0.048) and with better body condition (p = 0.038) were more likely to be paired. No relations were observed between independent variables and testosterone and testes mass. However, results suggested that seminiferous tubule diameter is influenced by a complex array of biologic and toxicologic parameters, which differ depending on pair status. Tubule diameters of paired male scaup were negatively influenced by hormones, whereas contaminants influenced diameter in unpaired male scaup. The effects of selenium were attenuated when bound with cadmium but not mercury. When selenium concentrations were high (greater than median value), there was a positive effect of cadmium on tubule diameter (R(2) = 0.30, n = 10, p = 0.007) but a negative relation with mercury (R(2) = 0.15, n = 10, p = 0.09). Seminiferous tubule diameter may be a sensitive indicator of sublethal effects of contaminants... /Selenium/

/BIRDS and MAMMALS/ Adverse effects of selenium (Se) in wild aquatic birds have been documented as a consequence of pollution of the aquatic environment by subsurface agricultural drainwater and other sources. These effects include mortality, impaired reproduction with teratogenesis, reduced growth, histopathological lesions and alterations in hepatic glutathione /(GSH)/ metabolism. ... Laboratory studies, mainly with an organic form of Se, selenomethionine, have revealed oxidative stress in different stages of the mallard (Anas platyrhynchos) life cycle. As dietary and tissue concentrations of Se increase, increases in plasma and hepatic GSH peroxidase activities occur, followed by dose-dependent increases in the ratio of hepatic oxidized to reduced glutathione /glutathione disulfide: glutathione/ (GSSG:GSH) and ultimately hepatic lipid peroxidation measured as an increase in thiobarbituric acid reactive substances (TBARS). One or more of these oxidative effects were associated with teratogenesis (4.6 ppm wet weight Se in eggs), reduced growth in ducklings (15 ppm Se in liver), diminished immune function (5 ppm Se in liver) and histopathological lesions (29 ppm Se in liver) in adults. Manifestations of Se-related effects on glutathione metabolism were also apparent in field studies in seven species of aquatic birds. Reduced growth and possibly immune function but increased liver:body weight and hepatic GSSG:GSH ratios were apparent in american avocet (Recurvirostra americana) hatchlings from eggs containing 9 ppm Se. In black-necked stilts (Himantopus mexicanus), which contained somewhat lower Se concentrations, a decrease in hepatic GSH was apparent with few other effects. In adult American coots (Fulica americana), signs of Se toxicosis included emaciation, abnormal feather loss and histopathological lesions. Mean liver concentrations of 28 ppm Se (ww) in the coots were associated with elevated hepatic GSH peroxidase, depletion of hepatic protein bound thiols and total thiols, but a small increase in GSH. Diving ducks in the San Francisco Bay area exhibited a positive correlation between hepatic Se concentration and GSH peroxidase activity (r=0.63, P<0.05), but a negative correlation between hepatic Se and GSH concentration (r=-0.740, P<0.05). In willets (Catoptrophorus semipalmatus) from the San Diego area, positive correlations occurred between hepatic Se concentration and GSSG (r=0.70, P<0.001), GSSG:GSH ratio, and TBARS. In emperor geese (Chen canagica) from western Alaska, blood levels of up to 9.4 ppm occurred and were associated with increased plasma GSH peroxidase activity (r=0.62, P<0.001), but with decreased plasma GSSG reductase activity. When evaluating Se toxicity, interactive nutritional factors, including other elements and dietary protein, should also be taken into consideration. Further studies are needed to examine the relationship between different forms of environmentally occurring selenium, arsenic and mercury on reproduction, hepatotoxicity and immune function of aquatic birds. Further selenium nutritional interaction studies may also help to illucidate the mechanism of selenium induced teratogenesis, by optimizing GSH and other antioxidant defense mechanisms in a manner that would stabilize or raise the cell's threshold for susceptibility to toxic attack from excess selenium. It is concluded that Se-related manifestations of oxidative stress may serve as useful bioindicators of Se exposure and toxicity in wild aquatic birds. /Selenium/

/BIRDS and MAMMALS/ ... American avocet (Recurvirostra americana) and black-necked stilt (Himantopus mexicanus) eggs were collected from three sites in the Tulare Lake Basin of California, USA, and hatched in the laboratory. These sites included the Tulare Lake Drainage District-north (TLDD-N, water 2.5 ppb Se), TLDD-south (TLDD-S, water 8.6 ppb Se), and Westfarmers (WF, water 190 ppb Se). Highest egg Se concentrations occurred at WF (geometric mean 31.4 ppm dry wt for avocets and 20.5 ppm dry wt for stilts). Mean egg Se concentrations were 6.7 ppm for avocets and 8.4 ppm for stilts at TLDD-S, and 3.3 ppm for avocets and 2.3 ppm for stilts at TLDD-N. Hatching success and incidence of malformations did not differ among sites, but yolk sac-free hatching weights and bone lengths were less for avocets at the WF site, whereas liver weights and liver to body weight ratios were greater at that site. With increasing Se concentration, oxidative stress was most apparent in avocet hatchlings from WF: hepatic glutathione (GSH) peroxidase activity increased, glucose-6-phosphate dehydrogenase activity decreased, and oxidized glutathione (GSSG) concentration as well as the ratio of GSSG to reduced GSH concentration increased. In stilts, hepatic GSH concentration was lower in WF hatchlings... /Selenium/

For more Ecotoxicity Excerpts (Complete) data for SELENIUM COMPOUNDS (28 total), please visit the HSDB record page.

3.90e+02

5.80e+03

2.10e+01

8.80e+01

1.00e+02

5.00e+01

5.20e-01

2.60e-01

5.00e-03

2.00e-02

Volatile

1.20e+03

1.80e+04

6.30e+01

2.60e+02

3.00e+02

The substance is very toxic to aquatic organisms. It is strongly advised not to let the chemical enter into the environment.

The production and use of selenium compounds as food additives in animal feeds, in anti-dandruff shampoos and dietary supplements, and in glass manufacturing and other industries, may result in their release to the environment through various waste streams; their use in fertilizers and former use in pesticides may have resulted in its direct release to the environment. The earth's crust contains an average of 0.05 to 0.09 ppm selenium. In nature, selenium usually occurs in the sulfide ores of heavy metals. It predominates in approximately 40 minerals, with higher levels being found in clausthalite, naumannite, tiemannite, and berzelianite. Selenium occurs in volcanic rock, sandstone, carbonaceous rocks, and some types of coal and mineral oil. In nature, selenium is found in the -2 (selenide), 0 (selenium), +4 (selenite), and +6 (selenate) oxidation states. Natural releases of selenium to air may result from biomethylation by plants and bacteria, and volcanic eruptions. Anthropogenic emissions may result from mining and milling operations, base metal smelting and refining, selenium refining, the burning of coal, oil, and solid waste, and from selenium's use in various industries. If released to the atmosphere, selenium is expected to exist predominately in the particulate phase. Particulate-phase selenium will be removed from the atmosphere by wet or dry deposition. The solubility and mobility of selenium are dependent upon its valence and chemical state. In soils, the behavior of selenium is affected by redox conditions, pH, hydrous oxide content, clay content, organic materials and the presence of competing anions. Selenium has sorptive affinity for hydrous metal oxides, clays and organic materials. Heavy metal selenides, which are insoluble and immobile, predominate in acidic soils and soils with high amounts of organic matter. In alkaline, well-oxidized soil environments, selenates (Se(VI)), which are very mobile, predominate; no sorption of sodium selenate was observed in 10 of 11 soils. Sodium and potassium selenites dominate in neutral, well-drained mineral soils. Selenite, Se(IV), is soluble, but can strongly adsorb to soil minerals and organic material; iron and manganese oxides sorb Se(IV). Se(IV) adsorption was observed to decrease with increasing pH from 4 to 9, and Se(VI) adsorption was minimal under most pH conditions. In soil and water, biological methylation of selenium species and subsequent volatilization of the alkyl selenides is expected to be an important fate process. If released into water, selenium is expected to form oxyanions and exhibit anionic chemistry; speciation will be determined by pH and redox potential of the solution. Selenates are stable under alkaline oxidizing conditions and are not expected to adsorb to suspended solids in the water column. Selenious acid species occur under the intermediate to slightly oxidizing conditions encountered in aerobic water. At pH less than 7 and under mildly reducing conditions, selenites are reduced to elemental selenium. In sediments, reduced and tightly bound selenium will remain relatively immobile unless the sediments are chemically or biologically oxidized. BCF values ranging from 200 to 3,600 for selenite and 65 to 500 for selenate suggest bioconcentration in aquatic organisms will be moderate to very high. Occupational exposure to selenium compounds may occur through inhalation of dust or powder, and dermal contact with these compounds at workplaces where they are produced or used. Monitoring data indicate that the general population may be exposed to selenium compounds via inhalation of ambient air, ingestion of food, drinking water and dietary supplements, and dermal contact with this compound or other consumer products, such as anti-dandruff shampoos and animal feeds, containing selenium. (SRC)

Selenium (Se) is an essential trace element, and its low status in humans has been linked to increased risk of various diseases, such as cancer and heart disease. In recent years, Se research has attracted tremendous interest because of its important role in antioxidant selenoproteins for protection against oxidative stress initiated by excess reactive oxygen species (ROS) and reactive nitrogen species (NOS). The synthesis of selenoproteins requires a unique incorporation of amino acid selenocysteine (Sec) into proteins directed by the UGA codon, which is also a termination codon. Interest in Se research has led to the discovery of at least 30 selenoproteins; however, the biochemical functional roles of some of these selenoproteins are still unknown. Besides in the form of selenoproteins, Se can exist in many different chemical forms in biological materials either as organic Se compounds, such as selenomethionine and dimethylselenide, and inorganic selenites and selenates. In foods, Se is predominantly present as selenomethionine, which is an important source of dietary Se in humans, and also as a chemical form that is commonly used for Se supplements in clinical trials.

Natural selenium contains six stable isotopes; 29 other isotopes have been characterized.

The earth's crust contains an average of 0.05 to 0.09 ppm selenium(1,2). In nature, it usually occurs in the sulfide ores of heavy metals; it is found in small quantities in pyrite and selenosulfur(1). Selenium is found in the -2 (selenide), 0 (selenium), +4 (selenite), and +6 (selenate) oxidation states(3,4), and predominates in approximately 40 minerals(2); higher levels occur in the minerals clausthalite (PbSe)(1), naumannite ((Ag,Pb)Se), tiemannite (HgSe), and berzelianite (Cu2Se)(2). Higher concns of selenium are found in volcanic rock, sandstone, uranium deposits, and carbonaceous rocks(2). Average selenium concns in igneous, sandstone, shale, and carbonates are 0.050, 0.52, 0.60 and 0.32 ppm, respectively(5). Bedrock contains selenium at concns ranging from <0.1 to 12 ppm(5). Selenium occurs in low concns in some types of coal and mineral oil(6). Selenium found in natural waters is mostly the result of weathering of seleniferous rock(7). Natural atmospheric releases of selenium result from volatilization, as a result of biomethylation, by plants and bacteria and from volcanic eruptions(8). Leaching and weathering of parent bedrock material may result in selenium's release to soil(8).

Selenium may be released to the environment from mining and milling operations; base metal smelting and refining; selenium refining; the burning of coal, oil and solid waste; and from its use in glass manufacture, electronics and electrical manufacturing, in duplicating equipment, in pigments, iron and steel alloying(1), in anti-dandruff shampoos, vitamin and mineral supplements, fungicides, and other commercial products(2). Its former use in pesticide products(2) may have resulted in its direct release to the environment. It was estimated that 2.4 million pounds of selenium was discharged into the atmosphere by industrial plants in 1970; burning of coal and production of copper accounted for 62% and 26% of the total, respectively(1). One study showed that about 53% of the selenium contained in coal was emitted to the atmosphere as volatilized selenium or included with particles of fly ash(1).

AQUATIC FATE: In aqueous solution, selenium forms oxyanions and exhibits anionic chemistry(1). Volatilization of the ionic forms of selenium is not expected to be an important fate process(SRC). Speciation of selenium is determined by the pH and redox potential of the solution; elemental selenium is favored by low pH and reducing conditions(1). At pHs <7 and under mildly reducing conditions, selenites are reduced to elemental selenium(1). Reducing conditions in surface sediments of ponded laboratory sediment columns promoted reduction of soluble Se(VI) to soluble Se(IV) to insoluble Se(0), allowing a net accumulation of insoluble elemental selenium(2). In sediments, reduced and tightly bound selenium will remain relatively immobile unless the sediments are chemically or biologically oxidized(3).

ATMOSPHERIC FATE: Hydrogen selenide released to the air is unstable and will be oxidized to elemental selenium and water. Selenium dioxide released to the air from the combustion of fossil fuels is expected to be reduced to elemental selenium by sulfur dioxide formed during the combustion(1).

TERRESTRIAL FATE: The behavior of selenium in soils is affected by redox conditions, pH, hydrous oxide content, clay content, organic materials and the presence of competing anions(1). Heavy metal selenides, which are insoluble, predominate in acidic soils and soils with high amounts of organic matter; selenium in this form is immobile(2). Sodium and potassium selenites dominate in neutral, well-drained mineral soils(2). Selenite (Se(IV)) is soluble, but can strongly adsorb to soil minerals and organic material(3). Iron and manganese oxides sorb Se(IV), with iron oxides sorbing more than manganese(4). In alkaline, well-oxidized soil environments, selenates, Se(VI) predominate; selenates are very mobile because of their high water solubility and low tendency to adsorb onto soil particles(2). No sorption of sodium selenate was observed in 10 of 11 soils; a log Kd value of 0.958 was determined in Kula soil (pH 5.9, 6.62% TOC, 73.7% sand, 25.4% silt, 0.9% clay)(5). Se(IV) adsorption was observed to decrease with increasing pH from 4 to 9 and Se(VI) adsorption was minimal under most pH conditions(4). In soils, elemental selenium and inorganic selenium compounds can be methylated by microorganisms and subsequently volatilize to the atmosphere(1,2); dimethylselenide and dimethyl diselenide are the principal products(2).

AQUATIC FATE: In aqueous solution, selenium forms oxyanions and exhibits anionic chemistry(1). Volatilization of the ionic forms of selenium is not expected to be an important fate process(SRC). Speciation of selenium is determined by the pH and redox potential of the solution; elemental selenium is favored by low pH and reducing conditions(1). Selenates are stable under alkaline oxidizing conditions(1). Selenious acid species occur under the intermediate to slightly oxidizing conditions encountered in aerobic water(1). Over the pH range of 3 to 9, the biselenite species predominates; at pHs >9, selenite is the major species(1). At pHs <7 and under mildly reducing conditions, selenites are reduced to elemental selenium(1). Reducing conditions in surface sediments of ponded laboratory sediment columns promoted reduction of soluble Se(VI) to soluble Se(IV) to insoluble Se(0), allowing a net accumulation of insoluble elemental selenium(2). In sediments, reduced and tightly bound selenium will remain relatively immobile unless the sediments are chemically or biologically oxidized(3). Biological methylation of selenium may occur in aquatic environments; inorganic selenium undergoes biological methylation to dimethyl selenide and dimethyl diselenide(1,4). Bioconcentration factors have been measured in a variety of aquatic organisms(SRC). Algae and daphnids concentrated (75)Se more strongly from selenite (BCFs ranged from 220 to 3,600) than selenate (BCFs ranged from 65 to 500)(5). BCF values for (75)Se after 28 days exposure to three selenium species were: 72 in macrophytes, 141 in periphyton, and 351 in zooplankton (as selenate); 363 in macrophytes, 755 in periphyton, and 1,087 in zooplankton (as selenite); and 3,266 in macropytes, 16,836 in periphyton, and 28,870 in zooplankton (as Se-methionine)(6).

ATMOSPHERIC FATE: Most selenium compounds are expected to exist solely in the particulate phase in the ambient atmosphere(1). Particulate-phase selenium may be removed from the air by wet or dry deposition(SRC). Volatile selenium compounds, selenium dioxide, hydrogen selenide, dimethyl selenide, and dimethyl diselenide, are expected to exist in the gaseous state in the atmosphere(1,2). Hydrogen selenide released to the air is unstable and will be oxidized to elemental selenium and water(2). Selenium dioxide released to the air from the combustion of fossil fuels is expected to be reduced to elemental selenium by sulfur dioxide formed during the combustion(2).

Biomethylation of selenium was optimal in a well-mixed, aerobic system amended with a protein source; removal, via volatilization of dimethyl selenide, ranged between 8 and 100% for peptone-amended evaporation pond waters containing between 2.2 and 0.02 ug/L Se, respectively(1). Microbial methylation of selenium can be stimulated in Se-contaminated sediments by specific organic amendments, such as addition of protein sources(2). Three freshwater green algae, isolated from the Tone River and Lake Kasumigaura in Japan, produced methylated selenium compounds from inorganic selenium compounds; trimethylselenonium ion and dimethyl selenide were identified as products(3). A variety of organisms, including benthic microflora, are capable of methylating selenium. Microbes present in lake sediments methylated organic and inorganic selenium compounds, including sodium selenite and sodium selenate. Gaseous dimethyl selenide and dimethyl diselenide were produced(4). Dimethylselenide, dimethyl diselenide, and another selenium compound tentatively identified as dimethyl selenone were evolved from brown-black loamy soil collected 1 cm under the ground surface inside selenium smelter grounds in Belgium, at rates of 8.2, 4.3, and 1.9 ng Se/day, respectively; this was attributed to natural biomethylation of selenium in the soils(5).

The solubility and mobility of selenium are dependent upon its valence and chemical state; under reducing conditions, selenium can form metal selenides, most of which have very low water solubilities, and volatile hydrogen selenide(1). Elemental selenium is favored by low pH and reducing conditions(1,2); under aerobic conditions, selenium is in the form of the selenite and selenate anions(1). Under acidic conditions, selenite is rapidly reduced to elemental selenium by mild reducing agents(1). An increase in pH from 5 to 7.5 led to greater dissolved concentrations of Se(IV) and Se(VI)(3). In ponded laboratory sediment columns, Se(VI) was sequentially reduced from Se(IV) to Se(0), with Se(0) occurring as early as 3.8 days after flooding in sediments amended with organic matter(4).

Generators of waste (equal to or greater than 100 kg/mo) containing this contaminant, EPA hazardous waste number D010, must conform with USEPA regulations in storage, transportation, treatment and disposal of waste.

SRP: Wastewater from contaminant suppression, cleaning of protective clothing/equipment, or contaminated sites should be contained and evaluated for subject chemical or decomposition product concentrations. Concentrations shall be lower than applicable environmental discharge or disposal criteria. Alternatively, pretreatment and/or discharge to a permitted wastewater treatment facility is acceptable only after review by the governing authority and assurance that "pass through" violations will not occur. Due consideration shall be given to remediation worker exposure (inhalation, dermal and ingestion) as well as fate during treatment, transfer and disposal. If it is not practicable to manage the chemical in this fashion, it must be evaluated in accordance with EPA 40 CFR Part 261, specifically Subpart B, in order to determine the appropriate local, state and federal requirements for disposal.

... As the price of selenium is very high; recovery of it by processing selenium containing waste is economical. For example, selenium refineries are equipped with wet scrubbers that employ an approx 50% soln of hydrobromic acid containing free bromine. The acid fumes are adsorbed in a lime and soda bed, and the selenium separated from the hydrobromic acid soln by distilliation is recycled. ... If possible, convert selenium compounds to an insoluble form with SO2 before landfill or solidification. Do not use metal and acid to reduce selenium compounds. This will produce toxic gaseous hydrogen selenide.

Depending upon the industrial source, selenium occurs in either the particulate or the soluble form. For the former, physical treatment processes such as sedimentation or filtration are quite effective. Lime precipitation of soluble selenium has been shown to be ineffective. Alum coagulation/coprecipitation is somewhat effective, with removal efficiencies approaching 50% achievable. Iron coagulation/coprecipitation is capable of above 80% selenium removal, with efficiency increasing with decreasing pH. Activated carbon adsorption is not effective, except in one reported instance involving high pH pretreatment. The most efficient process for soluble selenium appears to be anion exchange. Preoxidation of the selenite to selenate is reported to enhance exchange capacity. /Selenium compounds/

For more Disposal Methods (Complete) data for SELENIUM COMPOUNDS (7 total), please visit the HSDB record page.

/GUIDE 152: SUBSTANCES - TOXIC (COMBUSTIBLE)/ Health: Highly toxic, may be fatal if inhaled, swallowed or absorbed through skin. Contact with molten substance may cause severe burns to skin and eyes. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution. /Selenium powder/

/GUIDE 152: SUBSTANCES - TOXIC (COMBUSTIBLE)/ Fire or Explosion: Combustible material: may burn but does not ignite readily. Containers may explode when heated. Runoff may pollute waterways. Substance may be transported in a molten form. /Selenium powder/

/GUIDE 152: SUBSTANCES - TOXIC (COMBUSTIBLE)/ Public Safety: CALL Emergency Response Telephone Number ... As an immediate precautionary measure, isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at least 25 meters (75 feet) for solids. Keep unauthorized personnel away. Stay upwind. Keep out of low areas. /Selenium powder/

/GUIDE 152: SUBSTANCES - TOXIC (COMBUSTIBLE)/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Wear chemical protective clothing that is specifically recommended by the manufacturer. It may provide little or no thermal protection. Structural firefighters' protective clothing provides limited protection in fire situations ONLY; it is not effective in spill situations where direct contact with the substance is possible. /Selenium powder/

For more DOT Emergency Guidelines (Complete) data for SELENIUM, ELEMENTAL (8 total), please visit the HSDB record page.

/GUIDE 151: SUBSTANCES - TOXIC (NON-COMBUSTIBLE)/ Health: Highly toxic, may be fatal if inhaled, swallowed or absorbed through skin. Avoid any skin contact. Effects of contact or inhalation may be delayed. Fire may produce irritating, corrosive and/or toxic gases. Runoff from fire control or dilution water may be corrosive and/or toxic and cause pollution. /Selenium compound, NOS; Selenium compound, liquid, NOS; Selenium compound, solid, NOS/

/GUIDE 151: SUBSTANCES - TOXIC (NON-COMBUSTIBLE)/ Fire or Explosion: Non-combustible, substance itself does not burn but may decompose upon heating to produce corrosive and/or toxic fumes. Containers may explode when heated. Runoff may pollute waterways. /Selenium compound, NOS; Selenium compound, liquid, NOS; Selenium compound, solid, NOS/

/GUIDE 151: SUBSTANCES - TOXIC (NON-COMBUSTIBLE)/ Public Safety: CALL Emergency Response Telephone Number ... As an immediate precautionary measure, isolate spill or leak area in all directions for at least 50 meters (150 feet) for liquids and at lease 25 meters (75 feet) for solids. Keep unauthorized personnel away. Stay upwind. Keep out of low areas. /Selenium compound, NOS; Selenium compound, liquid, NOS; Selenium compound, solid, NOS/

/GUIDE 151: SUBSTANCES - TOXIC (NON-COMBUSTIBLE)/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Wear chemical protective clothing that is specifically recommended by the manufacturer. It may provide little or no thermal protection. Structural firefighters' protective clothing provides limited protection in fire situations ONLY; it is not effective in spill situations where direct contact with the substance is possible. /Selenium compound, NOS; Selenium compound, liquid, NOS; Selenium compound, solid, NOS/

For more DOT Emergency Guidelines (Complete) data for SELENIUM COMPOUNDS (8 total), please visit the HSDB record page.

2658 152(powder)

UN 2658; Selenium, powder

IMO 6.1; Selenium, powder

UN 3440; Selenium compound, liquid, n.o.s

UN 3283; Selenium compound, solid, n.o.s

No person may /transport,/ offer or accept a hazardous material for transportation in commerce unless that person is registered in conformance ... and the hazardous material is properly classed, described, packaged, marked, labeled, and in condition for shipment as required or authorized by ... /the hazardous materials regulations (49 CFR 171-177)./

The International Maritime Dangerous Goods Code lays down basic principles for transporting hazardous chemicals. Detailed recommendations for individual substances and a number of recommendations for good practice are included in the classes dealing with such substances. A general index of technical names has also been compiled. This index should always be consulted when attempting to locate the appropriate procedures to be used when shipping any substance or article.

Airtight. Do not transport with food and feedstuffs.

Symbol: T; R: 23/25-33-53; S: (1/2)-20/21-28-45-61