NILE
CHEMICALS
Synonyms: Mercury (II) oxide; mercuric oxide red; 
mercuric oxide yellow 
CAS No.: 21908-53-2 
Molecular Weight: 216.59 
Chemical Formula: HgO 
Product Codes:131134 
Ingredient CAS No Percent Hazardous
--------------------------------------- ------------ ------------ ---------
Mercury Oxide 21908-53-2 90 - 100% Yes
Inhalation: Causes irritation to the respiratory tract. Symptoms include 
sore throat, coughing, pain, tightness in chest, breathing difficulties, 
shortness of breath and headache. Pneumonitis may develop. Can be absorbed 
through inhalation with symptoms to parallel ingestion. 
Ingestion: Highly Toxic! Average lethal dose for inorganic mercury salts 
is about 1 gram. May cause burning of the mouth and pharynx, abdominal pain, 
vomiting, corrosive ulceration, bloody diarrhea. May be followed by a rapid and 
weak pulse, shallow breathing, paleness, exhaustion, central nervous system 
problems, tremors and collapse. Delayed death may occur from renal failure. 
Skin Contact: Causes irritaton. Symptoms include redness and pain. May 
cause burns. May cause sensitization. Can be absorbed through the skin with 
symptoms to parallel ingestion. 
Eye Contact: Causes irritation and burns to eyes. Symptoms include 
redness, pain, blurred vision; may cause serious and permanent eye damage. 
Chronic Exposure: Chronic exposure through any route can produce central 
nervous system damage. May cause muscle tremors, personality and behavior 
changes, memory loss, metallic taste, loosening of the teeth, digestive 
disorders, skin rashes, brain damage and kidney damage. Can cause skin allergies 
and accumulate in the body. Repeated skin contact can cause the skin to turn 
gray in color. Not a known reproductive hazard, but related mercury compounds 
can damage the developing fetus and decrease fertility in males and females. 
Aggravation of Pre-existing Conditions: Persons with nervous disorders, 
or impaired kidney or respiratory function, or a history of allergies or a known 
sensitization to mercury may be more susceptible to the effects of the 
substance. 
Inhalation: Remove to fresh air. If not breathing, 
give artificial respiration. If breathing is difficult, give oxygen. Get medical 
attention immediately. 
Ingestion: Induce vomiting immediately as directed by medical personnel. 
Never give anything by mouth to an unconscious person. Get medical attention 
immediately. 
Skin Contact: Immediately flush skin with plenty of water for at least 15 
minutes while removing contaminated clothing and shoes. Get medical attention 
immediately. Wash clothing before reuse. Thoroughly clean shoes before reuse.
Eye Contact: Immediately flush eyes with plenty of water for at least 15 
minutes, lifting lower and upper eyelids occasionally. Get medical attention 
immediately. 
Fire: Substance is a strong oxidizer and its heat of 
reaction with reducing agents or combustibles may cause ignition. Upon heating 
it decomposes to form oxygen, which increases the flammability of combustibles.
Explosion: Not considered to be an explosion hazard. 
Fire Extinguishing Media: Use any means suitable for extinguishing 
surrounding fire. Do not allow water runoff to enter sewers or waterways. 
Special Information: In the event of a fire, wear full protective 
clothing and NIOSH-approved self-contained breathing apparatus with full 
facepiece operated in the pressure demand or other positive pressure mode. 
Ventilate area of leak or 
spill. Wear appropriate personal protective equipment as specified in Section 8.
Keep in a tightly closed container, stored in a cool, dry, ventilated area. Protect against physical damage and moisture. Isolate from any source of heat or ignition. Avoid storage on wood floors. Separate from incompatibles, combustibles, organic or other readily oxidizable materials. Isolate from any source of heat or ignition. Do not use or store on porous work surfaces (wood, unsealed concrete, etc.). Protect from light. Follow strict hygiene practices. Containers of this material may be hazardous when empty since they retain product residues (dust, solids); observe all warnings and precautions listed for the product.
Airborne Exposure Limits: - OSHA Acceptable Ceiling 
Concentration:
mercury and mercury compounds: 0.1 mg/m3 (TWA), skin- ACGIH Threshold Limit 
Value (TLV): inorganic and metallic mercury, as Hg: 0.025 mg/m3 (TWA) skin, A4 
Not classifiable as a human carcinogen.- ACGIH Biological Exposure Indices:
total inorganic mercury in urine (preshift): 35 ug/g creatinine;total inorganic 
mercury in blood (end of shift): 15 ug/l. 
Ventilation System: A system of local and/or general exhaust is 
recommended to keep employee exposures below the Airborne Exposure Limits. Local 
exhaust ventilation is generally preferred because it can control the emissions 
of the contaminant at its source, preventing dispersion of it into the general 
work area. Please refer to the ACGIH document, Industrial Ventilation, A 
Manual of Recommended Practices, most recent edition, for details. 
Personal Respirators (NIOSH Approved): If the exposure limit is exceeded 
and engineering controls are not feasible, a full facepiece particulate 
respirator (NIOSH type N100 filters) may be worn for up to 50 times the exposure 
limit or the maximum use concentration specified by the appropriate regulatory 
agency or respirator supplier, whichever is lowest. If oil particles (e.g. 
lubricants, cutting fluids. glycerine, etc.) are present, use a NIOSH type R or 
P filter. For emergencies or instances where the exposure levels are not known, 
use a full-facepiece positive-pressure, air-supplied respirator. WARNING: 
Air-purifying respirators do not protect workers in oxygen-deficient 
atmospheres. 
Skin Protection: Wear impervious protective clothing, including boots, 
gloves, lab coat, apron or coveralls, as appropriate, to prevent skin contact.
Eye Protection: Use chemical safety goggles and/or full face shield where 
dusting or splashing of solutions is possible. Maintain eye wash fountain and 
quick-drench facilities in work area. 
Appearance: Bright, orange-red or orange-yellow 
powder. 
Odor: Odorless. 
Solubility: Insoluble in water. 
Specific Gravity: 11.14 
pH: No information found. 
% Volatiles by volume @ 21C (70F): 0 
Boiling Point: Not applicable. 
Melting Point: 500C (932F) 
Vapor Density (Air=1): No information found. 
Vapor Pressure (mm Hg): No information found. 
Evaporation Rate (BuAc=1): 0.6 
Stability: Stable under ordinary conditions of use 
and storage. Decomposes on exposure to light into mercury and oxygen. At 400C 
becomes almost black but red again on cooling. 
Hazardous Decomposition Products: Emits toxic mercury vapors. 
Hazardous Polymerization: This substance does not polymerize. 
Incompatibilities: Reacts with reducing materials. Incompatible with 
chlorine, hydrazine hydrate, hydrogen peroxide, hydrogen trisulfide, 
hypophosphorous acid, iodine plus methanol plus ethanol, magnesium, phosphorus, 
phospham, sodium potassium alloy, sulfur, acetyl nitrate, butadiene, 
hydrocarbons, sulfur chloride, methanethiol. 
Conditions to Avoid: Light, heat, incompatibles. 
Toxicological Data: Oral rat LD50: 18 mg/kg. 
Investigated as a tumorigen and a reproductive effector. 
Reproductive Toxicity: All forms of mercury can cross the placenta to the 
fetus, but most of what is known has been learned from experimental animals. See 
Chronic Health Hazards. 
--------\Cancer Lists\------------------------------------------------------
---NTP Carcinogen---
Ingredient Known Anticipated IARC Category
------------------------------------ ----- ----------- -------------
Mercury Oxide (21908-53-2) No No 3
Environmental Fate: For mercury: This material has 
an experimentally-determined bioconcentration factor (BCF) of greater than 100. 
This material is expected to significantly bioaccumulate. 
Environmental Toxicity: For mercury: This material is expected to be 
toxic to aquatic life. The LC50/96-hour values for fish are less than 1 mg/l.
Whatever cannot be saved for recovery or recycling should be handled as hazardous waste and sent to a RCRA approved waste facility. Processing, use or contamination of this product may change the waste management options. State and local disposal regulations may differ from federal disposal regulations. Dispose of container and unused contents in accordance with federal, state and local requirements.
Domestic (Land, D.O.T.) 
----------------------- 
Proper Shipping Name: MERCURY OXIDE 
Hazard Class: 6.1 
UN/NA: UN1641 
Packing Group: II 
Information reported for product/size: 2.5KG 
International (Water, I.M.O.) 
----------------------------- 
Proper Shipping Name: MERCURY OXIDE 
Hazard Class: 6.1 
UN/NA: UN1641 
Packing Group: II 
Information reported for product/size: 2.5KG 
International (Air, I.C.A.O.) 
----------------------------- 
Proper Shipping Name: MERCURY OXIDE 
Hazard Class: 6.1 
UN/NA: UN1641 
Packing Group: II 
Information reported for product/size: 2.5KG 
--------\Chemical Inventory Status - Part 1\---------------------------------
Ingredient TSCA EC Japan Australia
----------------------------------------------- ---- --- ----- ---------
Mercury Oxide (21908-53-2) Yes Yes Yes Yes
--------\Chemical Inventory Status - Part 2\---------------------------------
--Canada--
Ingredient Korea DSL NDSL Phil.
----------------------------------------------- ----- --- ---- -----
Mercury Oxide (21908-53-2) Yes Yes No Yes
--------\Federal, State & International Regulations - Part 1\----------------
-SARA 302- ------SARA 313------
Ingredient RQ TPQ List Chemical Catg.
----------------------------------------- --- ----- ---- --------------
Mercury Oxide (21908-53-2) 500 500* No Mercury comp
--------\Federal, State & International Regulations - Part 2\----------------
-RCRA- -TSCA-
Ingredient CERCLA 261.33 8(d)
----------------------------------------- ------ ------ ------
Mercury Oxide (21908-53-2) 1 No No
Chemical Weapons Convention: No TSCA 12(b): No CDTA: No
SARA 311/312: Acute: Yes Chronic: Yes Fire: No Pressure: No
Reactivity: No (Pure / Solid)
WARNING: THIS PRODUCT CONTAINS A CHEMICAL(S) KNOWN 
TO THE STATE OF CALIFORNIA TO CAUSE BIRTH DEFECTS OR OTHER REPRODUCTIVE HARM.
Australian Hazchem Code: 2Z 
Poison Schedule: S7 
WHMIS: This MSDS has been prepared according to the hazard criteria of 
the Controlled Products Regulations (CPR) and the MSDS contains all of the 
information required by the CPR. 
Disclaimer: Nile Chemicals. provides the 
information contained herein in good faith but makes no representation as to its 
comprehensiveness or accuracy. This document is intended only as a guide to the 
appropriate precautionary handling of the material by a properly trained person 
using this product. Individuals receiving the information must exercise their 
independent judgment in determining its appropriateness for a particular 
purpose. NILE CHEMICALS. MAKES NO REPRESENTATIONS OR WARRANTIES, EITHER EXPRESS 
OR IMPLIED, INCLUDING WITHOUT LIMITATION ANY WARRANTIES OF MERCHANTABILITY, 
FITNESS FOR A PARTICULAR PURPOSE WITH RESPECT TO THE INFORMATION SET FORTH 
HEREIN OR THE PRODUCT TO WHICH THE INFORMATION REFERS. ACCORDINGLY, NILE 
CHEMICALS. WILL NOT BE RESPONSIBLE FOR DAMAGES RESULTING FROM USE OF OR RELIANCE 
UPON THIS INFORMATION. 
  
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