Selenomethionine SDS/MSDS (Safety Data Sheet)

3.1 Substances
Product name: Selenomethionine
CAS Number: 1464-42-2
PubChem CID: 15103
Molecular formula: C5H11NO2Se
Molecular weight: 196.12 g/mol
IUPAC name: 2-amino-4-methylselanylbutanoic acid

3.2 Mixtures
Not applicable (pure substance).

4.1 Description of first aid measures
Inhalation: Move to fresh air. Keep at rest in a position comfortable for breathing. Seek medical attention if symptoms persist.
Skin contact: Wash with plenty of soap and water. Remove contaminated clothing. Seek medical attention if irritation develops.
Eye contact: Rinse cautiously with water for several minutes. Remove contact lenses if present and easy to do. Continue rinsing. Seek medical attention.
Ingestion: Rinse mouth. Do NOT induce vomiting unless directed by medical personnel. Seek medical attention.

4.2 Most important symptoms and effects, both acute and delayed
See Section 11 (Toxicological Information).

4.3 Indication of any immediate medical attention and special treatment needed
Treat symptomatically. Contact a poison control center or physician for severe exposure.

5.1 Extinguishing media
Suitable: Water spray, dry chemical, carbon dioxide (CO2), alcohol-resistant foam.
Unsuitable: None known.

5.2 Specific hazards arising from the substance or mixture
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/

5.3 Advice for firefighters
Wear self-contained breathing apparatus (SCBA) and full protective clothing.
Fight fire from upwind. Cool containers with water spray until fire is extinguished.

6.1 Personal precautions, protective equipment and emergency procedures
Wear appropriate personal protective equipment (see Section 8).
Avoid breathing dust/vapor. Ensure adequate ventilation.
Evacuate personnel to safe areas. Keep people away from and upwind of spill.
WARNING: Highly toxic — only trained personnel should handle spills.

6.2 Environmental precautions
Prevent product from entering drains, waterways, or soil.
Contain spill with inert absorbent material.

6.3 Methods and materials for containment and cleaning up
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.
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.
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/
Personnel protection: Avoid breathing vapors. Keep upwind. Do not handle broken packages unless wearing appropriate personal protective equipment. /Selenium compound, solid, nos/
The worker should immediately wash the skin when it becomes contaminated. /Selenium/
Work clothing that becomes wet or significantly contaminated should be removed or replaced. /Selenium/

7.1 Precautions for safe handling
Handle in accordance with good industrial hygiene and safety practices.
Wear appropriate PPE (see Section 8). Avoid contact with skin, eyes, and clothing.
Wash hands thoroughly after handling. Do not eat, drink, or smoke in work area.
Avoid dust formation. Use only in a chemical fume hood or well-ventilated area.

7.2 Conditions for safe storage, including any incompatibilities
Store in a cool, dry, well-ventilated area. Keep container tightly closed.
Store away from incompatible materials (see Section 10).
Protect from light and moisture.
Recommended storage (industry convention for research compounds): -20°C for long-term storage; 2-8°C for short-term use and transport.
[Note: This is a general industry recommendation. Always verify exact storage conditions with the supplier Certificate of Analysis (COA).]

9.1 Information on basic physical and chemical properties
a) Appearance: DL- and L-forms are solids; [Merck Index] White crystalline solid; [Sigma-Aldrich MSDS]
b) Odor: No data available
c) Odor threshold: No data available
d) pH: No data available
e) Melting point/freezing point: 265 °C (decomposes)
f) Initial boiling point and boiling range: No data available
g) Flash point: No data available
h) Evaporation rate: No data available
i) Flammability (solid, gas): No data available
j) Upper/lower flammability or explosive limits: No data available
k) Vapor pressure: 0.00000008 [mmHg]
l) Vapor density: No data available
m) Relative density: No data available
n) Water solubility: Soluble in DMSO; slightly soluble in water
o) Partition coefficient: n-octanol/water: Log P: No data available
p) Auto-ignition temperature: No data available
q) Decomposition temperature: No data available
r) Viscosity: No data available
s) Explosive properties: No data available
t) Oxidizing properties: No data available

9.2 Other information
Topological Polar Surface Area (TPSA): 63.3 Ų
Complexity: 97

11.1 Information on toxicological effects
Acute toxicity:
No acute toxicity data available.
Skin corrosion/irritation:
Causes skin irritation (H315).
Serious eye damage/eye irritation:
Causes serious eye irritation (H319).
Respiratory or skin sensitization:
No data available.
Germ cell mutagenicity:
No data available.
Carcinogenicity:
No data available.
Reproductive toxicity:
No data available.
Specific target organ toxicity (single exposure):
H373
Specific target organ toxicity (repeated exposure):
No data available.
Aspiration hazard:
No data available.

11.2 Additional information
No additional toxicological information available.

12.1 Toxicity
LC50; Species: Daphnia magna (Water flea, neonate); Conditions: freshwater, renewal, 20 °C, pH 8.2, hard water, dissolved oxygen 8.6 mg/L; Concentration: 310 ug/L for 48 hr (95% confidence interval: 210-470 ug/L)
LC50; Species: Oncorhynchus tshawytscha (Chinook Salmon, fry, weight 0.5 g); Conditions: freshwater, static, 12 °C; Concentration: >21600 ug/L for 24, 96 hr
LC50; Species: Oncorhynchus tshawytscha (Chinook Salmon, fry, weight 2.6 g); Conditions: saltwater, static, 12 °C; Concentration: >23600 ug/L for 24, 96 hr
LC50; Species: Chironomus decorus (Midge, 4th instar); Conditions: freshwater, renewal, 20 °C, pH 8.1-8.3, hardness 85.0 mg/L CaCO3, dissolved oxygen 8.6 mg/L; Concentration: 194000 ug/L for 48 hr (95% confidence interval: 57000-819000 ug/L)
/BIRDS and MAMMALS/ ... The presence of excess selenium analogs of sulfur-containing enzymes and structural proteins /may/ play a role in avian teratogenesis. L-selenomethionine is the most likely major dietary form of selenium encountered by aquatic birds, with lesser amounts of L-selenocysteine ingested from aquatic animal foods. The literature is suggestive that L-selenomethionine is not any more toxic to adult birds than other animals. L-Selenomethionine accumulates in tissue protein of adult birds and in the protein of egg white as would be expected ... . There is no suggestion from the literature that the levels of L-selenomethionine that would be expected to accumulate in eggs in the absence of environmental concent

12.2 Persistence and degradability
No data available.

12.3 Bioaccumulative potential
No data available.

12.4 Mobility in soil
No data available.

12.5 Results of PBT and vPvB assessment
PBT/vPvB assessment not available.

12.6 Other adverse effects
This substance is classified as hazardous to the aquatic environment.

13.1 Waste treatment methods
Waste Treatment Methods: Waste material must be disposed of in accordance with national and local regulations. Leave chemicals in original containers and do not mix with other waste. Handle uncleaned containers in the same manner as the product itself.

14.1 UN number
UN 3283

14.2 UN proper shipping name
Selenium compound, solid, n.o.s

14.3 Transport hazard class(es)
Consult official transport regulations (DOT/IATA/IMDG) for hazard classification.

14.4 Packing group
Consult official transport regulations (DOT/IATA/IMDG) for packing group assignment.

14.5 Environmental hazards
Marine pollutant: Yes (classified as environmentally hazardous per GHS).

14.6 Special precautions for user
Transport in original packaging. Ensure containers are tightly sealed.
For bulk or commercial quantities, consult applicable transport regulations (DOT, IATA, IMDG).

14.7 Transport in bulk according to Annex II of MARPOL 73/78 and the IBC Code
Not applicable.

15.1 Safety, health and environmental regulations/legislation specific for the substance or mixture
US EPA / TSCA: Subject to EPA TSCA regulations
EU ECHA / REACH: Not available in public databases.

SARA 302 Components:
No chemicals in this material are subject to the reporting requirements of SARA Title III, Section 302.
SARA 313 Components:
This material does not contain any chemical components with known CAS numbers that exceed the threshold (De Minimis) reporting levels established by SARA Title III, Section 313.
SARA 311/312 Hazards:
Acute (short-term) health hazard
Chronic (long-term) health hazard
Environmental hazard

Massachusetts Right To Know Components:
This material contains components subject to the Massachusetts Right to Know Act. See Section 2 for hazard classification.
Pennsylvania Right To Know Components:
This material contains components subject to the Pennsylvania Right to Know Act. See Section 2 for hazard classification.
New Jersey Right To Know Components:
This material contains components subject to the New Jersey Right to Know Act. See Section 2 for hazard classification.

California Prop. 65 Components:
This product does not contain any chemicals known to the State of California to cause cancer, birth defects, or any other reproductive harm.

Other regulatory listings:
- Atmospheric Standards: Listed as a hazardous air pollutant (HAP) generally known or suspected to cause serious health problems. The Clean Air Act, as amended in 1990, directs EPA to set standards requiring major sources to sharply reduce routine emissions of toxic pollutants. EPA is required to establish and phase in spec
- Federal Drinking Water Standards: Maximum contaminant levels for inorganic contaminants: 0.05 mg/L /Selenium/
- Federal Drinking Water Guidelines: Maximum contaminant level goals for inorganic contaminants: 0.05 mg/L /Selenium/
- State Drinking Water Standards: (AZ) ARIZONA 10 ug/L /Selenium/
(NY) NEW YORK 10 ug/L /Selenium/
- State Drinking Water Guidelines: (AZ) ARIZONA 45 ug/L /Selenium/
(CT) CONNECTICUT 10 ug/L /Selenium/
(ME) MAINE 35 ug/L /Selenium/
(MN) MINNESOTA 30 ug/L /Selenium/

15.2 Chemical safety assessment
A chemical safety assessment has not been carried out for this substance.
For research-use-only compounds, no CSA is required under REACH Annex I.

Revision Date: 2026/09/09
Further Information: The information provided is believed to be correct but is not exhaustive and should be used only as a guideline based on current knowledge. It does not represent a guarantee of the properties of the product. Selleck Chemicals Corporation and its Affiliates shall not be held liable for any damage resulting from handling or contact with the product.