Mesityl oxide

H226: Flammable liquid and vapor [Warning Flammable liquids]

H302: Harmful if swallowed [Warning Acute toxicity, oral]

H312: Harmful in contact with skin [Warning Acute toxicity, dermal]

H332: Harmful if inhaled [Warning Acute toxicity, inhalation]

P210, P233, P240, P241, P242, P243, P261, P264, P270, P271, P280, P301+P317, P302+P352, P303+P361+P353, P304+P340, P317, P321, P330, P362+P364, P370+P378, P403+P235, and P501 (click each P-code to see the statement)

This chemical does not meet GHS hazard criteria for 0.6% (11 of 1711) of reports.

H226 (99.4%): Flammable liquid and vapor [Warning Flammable liquids]

H302 (99.4%): Harmful if swallowed [Warning Acute toxicity, oral]

H312 (98.9%): Harmful in contact with skin [Warning Acute toxicity, dermal]

H315 (12.2%): Causes skin irritation [Warning Skin corrosion/irritation]

H319 (12.2%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]

H331 (14.5%): Toxic if inhaled [Danger Acute toxicity, inhalation]

H332 (84.7%): Harmful if inhaled [Warning Acute toxicity, inhalation]

H335 (12.2%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

P210, P233, P240, P241, P242, P243, P261, P264, P264+P265, P270, P271, P280, P301+P317, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P316, P317, P319, P321, P330, P332+P317, P337+P317, P362+P364, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 1711 reports by companies from 15 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Reported as not meeting GHS hazard criteria per 11 of 1711 reports by companies.

There are 14 notifications provided by 1700 of 1711 reports by companies with hazard statement code(s).

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.

H315: Causes skin irritation [Warning Skin corrosion/irritation]

H319: Causes serious eye irritation [Warning Serious eye damage/eye irritation]

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

H335: May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

H336: May cause drowsiness or dizziness [Warning Specific target organ toxicity, single exposure; Narcotic effects]

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

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

H402: Harmful to aquatic life [Hazardous to the aquatic environment, acute hazard]

P203, P210, P233, P240, P241, P242, P243, P260, P261, P264, P264+P265, P270, P271, P273, P280, P301+P317, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P316, P318, P319, P321, P330, P332+P317, P337+P317, P362+P364, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

P203, P210, P233, P240, P241, P242, P243, P260, P261, P264, P264+P265, P270, P271, P280, P301+P317, P302+P352, P303+P361+P353, P304+P340, P305+P351+P338, P316, P318, P319, P321, P330, P332+P317, P337+P317, P362+P364, P370+P378, P403+P233, P403+P235, P405, and P501 (click each P-code to see the statement)

Fresh air, rest. Artificial respiration may be needed. Refer immediately for medical attention.

Remove contaminated clothes. Rinse and then wash skin with water and soap. Refer for medical attention .

First rinse with plenty of water for several minutes (remove contact lenses if easily possible), then refer for medical attention.

Rinse mouth. Do NOT induce vomiting. Refer immediately for medical attention.

Excerpt from NIOSH Pocket Guide for Mesityl oxide:

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: WATER FLUSH IMMEDIATELY - If this chemical contacts the skin, immediately flush the contaminated skin with water. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water. 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:

· Call 911 or emergency medical service.

· Ensure that medical personnel are aware of the material(s) involved, take precautions to protect themselves and avoid contamination.

· Move victim to fresh air if it can be done safely.

· Administer oxygen if breathing is difficult.

· If victim is not breathing:

-- DO NOT perform mouth-to-mouth resuscitation; the victim may have ingested or inhaled the substance.

-- If equipped and pulse detected, wash face and mouth, then give artificial respiration using a proper respiratory medical device (bag-valve mask, pocket mask equipped with a one-way valve or other device).

-- If no pulse detected or no respiratory medical device available, provide continuous compressions. Conduct a pulse check every two minutes or monitor for any signs of spontaneous respirations.

· Remove and isolate contaminated clothing and shoes.

· For minor skin contact, avoid spreading material on unaffected skin.

· In case of contact with substance, remove immediately by flushing skin or eyes with running water for at least 20 minutes.

· For severe burns, immediate medical attention is required.

· Effects of exposure (inhalation, ingestion, or skin contact) to substance may be delayed.

· Keep victim calm and warm.

· Keep victim under observation.

· For further assistance, contact your local Poison Control Center.

· Note: Basic Life Support (BLS) and Advanced Life Support (ALS) should be done by trained professionals.

Specific First Aid:

· Wash skin with soap and water.

· In case of burns, immediately cool affected skin for as long as possible with cold water. Do not remove clothing if adhering to skin.

In Canada, an Emergency Response Assistance Plan (ERAP) may be required for this product. Please consult the shipping paper and/or the "ERAP" section.

(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: Water flush immediately - If this chemical contacts the skin, immediately flush the contaminated skin with water. If this chemical penetrates the clothing, immediately remove the clothing and flush the skin with water. 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 129 [Flammable Liquids (Water-Miscible / Noxious)]:

CAUTION: The majority of these products have a very low flash point. Use of water spray when fighting fire may be inefficient.

SMALL FIRE: Dry chemical, CO2, water spray or alcohol-resistant foam. Do not use dry chemical extinguishers to control fires involving nitromethane (UN1261) or nitroethane (UN2842).

LARGE FIRE: Water spray, fog or alcohol-resistant foam. Avoid aiming straight or solid streams directly onto the product. If it can be done safely, move undamaged containers away from the area around the fire.

FIRE INVOLVING TANKS, RAIL TANK CARS OR HIGHWAY TANKS: Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles. 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 alcohol-resistant foam, powder, carbon dioxide. In case of fire: keep drums, etc., cool by spraying with water.

Use dry chemical, foam, carbon dioxide, or water spray. Water may be ineffective. Use water spray to keep fire-exposed containers cool.

If material /is/ on fire or involved in fire: Do not extinguish fire unless flow can be stopped. Use water in flooding quantities as fog. Solid streams of water may spread fire. Cool all affected containers with flooding quantities of water. Apply water from as far a distance as possible. Use "alcohol" foam, dry chemical or carbon dioxide.

Aqueous film-forming foam (AFFF), alcohol-resistant foam, powder, carbon dioxide.

A harmful contamination of the air can be reached rather quickly on evaporation of this substance at 20 °C.

Vapors are heavier than air (vapor-air density at 100 °F, 1.1) and may travel to a source of ignition and flash back.

· CALL 911. Then call emergency response telephone number on shipping paper. If shipping paper not available or no answer, refer to appropriate telephone number listed on the inside back cover.

· Keep unauthorized personnel away.

· Stay upwind, uphill and/or upstream.

· Ventilate closed spaces before entering, but only if properly trained and equipped.

· ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area.

· All equipment used when handling the product must be grounded.

· Do not touch or walk through spilled material.

· Stop leak if you can do it without risk.

· Prevent entry into waterways, sewers, basements or confined areas.

· A vapor-suppressing foam may be used to reduce vapors.

· Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers.

· Use clean, non-sparking tools to collect absorbed material.

Large Spill

· Dike far ahead of liquid spill for later disposal.

· Water spray may reduce vapor, but may not prevent ignition in closed spaces.

Excerpt from ERG Guide 129 [Flammable Liquids (Water-Miscible / Noxious)]:

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

LARGE SPILL: Consider initial downwind evacuation for at least 300 meters (1000 feet).

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)

Immediate precautionary measure

· Isolate spill or leak area for at least 50 meters (150 feet) in all directions.

· Consider initial downwind evacuation for at least 300 meters (1000 feet).

· 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.

Personal protection: self-contained breathing apparatus. Ventilation. Do NOT let this chemical enter the environment. Collect leaking liquid in sealable containers. Absorb remaining liquid in sand or inert absorbent. Then store and dispose of according to local regulations.

Eliminate all ignition sources. Stop or control the leak, if it can be done without undue risk. Use appropriate foam to blanket release and suppress vapors. Approach release from upwind. Absorb in noncombustible material for proper disposal.

Absorb on paper. Evaporate on a glass or iron dish in hood. Burn the paper.

Ventilation. Collect leaking liquid in sealable containers. Absorb remaining liquid in sand or inert absorbent and remove to safe place. Do NOT wash away into sewer. (Extra personal protection: self-contained breathing apparatus).

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

If mesityl oxide gets into the eyes, flush them immediately with large amounts of water for 15 minutes, lifting the lower and upper lids occasionally. Get medical attention as soon as possible. Contact lenses should not be worn when working with this chemical.

If mesityl oxide gets on the skin, wash it immediately with soap and water. If mesityl oxide penetrates the clothing, remove the clothing immediately and wash the skin with soap and water. Get medical attention promptly.

If a worker has been incapacitated, move the affected worker from the hazardous exposure. Put into effect the established emergency rescue procedures. Do not become a casualty. Understand the facility's emergency rescue procedures and know the locations of rescue equipment before the need arises.

SRP: Local exhaust ventilation should be applied wherever there is an incidence of point source emissions or dispersion of regulated contaminants in the work area. Ventilation control of the contaminant as close to its point of generation is both the most economical and safest method to minimize personnel exposure to airborne contaminants.

For more Preventive Measures (Complete) data for MESITYL OXIDE (13 total), please visit the HSDB record page.

Excerpt from ERG Guide 129 [Flammable Liquids (Water-Miscible / Noxious)]:

ELIMINATE all ignition sources (no smoking, flares, sparks or flames) from immediate area. All equipment used when handling the product must be grounded. Do not touch or walk through spilled material. Stop leak if you can do it without risk. Prevent entry into waterways, sewers, basements or confined areas. A vapor-suppressing foam may be used to reduce vapors. Absorb or cover with dry earth, sand or other non-combustible material and transfer to containers. Use clean, non-sparking tools to collect absorbed material.

LARGE SPILL: Dike far ahead of liquid spill for later disposal. Water spray may reduce vapor, but may not prevent ignition in closed spaces. (ERG, 2024)

Fireproof. Separated from strong oxidants and acids. Do NOT store or transport in containers made from plastic or copper. Cool. Keep in the dark. Store in an area without drain or sewer access.

Fireproof. Separated from strong oxidants. Cool. Keep in the dark.

Protect containers against physical damage. Store well-ventilated cool place, isolating from oxidizing materials. Outdoor or isolated place from inhabitants is preferable. In case of outdoor storage, use standard combustible liquid storage room or cabinet.

· Wear positive pressure self-contained breathing apparatus (SCBA).

· Structural firefighters' protective clothing provides thermal protection but only limited chemical protection.

2.0 [ppm]

25 [ppm]

830 [ppm]

5000 [ppm]

10 ppm (40 mg/m³)

TWA 10 ppm (40 mg/m3)

25.0 [ppm]

25 ppm (100 mg/m³)

TWA 25 ppm (100 mg/m3) See Appendix G

1400 ppm ; Based on 10% of the lower explosive limit. (NIOSH, 2024)

1400.0 [ppm]

Excerpts from Documentation for IDLHs: Human data: The probable response to 100 ppm was predicted to be eye and mucous membrane irritation, difficulty breathing, headache, and vertigo [Shell 1957]. It has been stated that 5,000 ppm might be dangerous to life in 30 to 60 minutes [Smyth et al. 1942].

1400 ppm [Based on 10% of the lower explosive limit for safety considerations even though the relevant toxicological data indicated that irreversible health effects or impairment of escape existed only at higher concentrations.]

1400 ppm

1400 ppm [10%LEL]

See: 141797

15.0 [ppm]

8 hr Time Weighted Avg (TWA): 15 ppm; 15 min Short Term Exposure Limit (STEL): 25 ppm.

15 ppm as TWA; 25 ppm as STEL.

15 ppm [1992]

25 ppm [1992]

8.1 mg/m

CAUTION: The majority of these products have a very low flash point. Use of water spray when fighting fire may be inefficient.

Small Fire

· Dry chemical, CO2, water spray or alcohol-resistant foam.

· Do not use dry chemical extinguishers to control fires involving nitromethane (UN1261) or nitroethane (UN2842).

Large Fire

· Water spray, fog or alcohol-resistant foam.

· Avoid aiming straight or solid streams directly onto the product.

· If it can be done safely, move undamaged containers away from the area around the fire.

Fire Involving Tanks, Rail Tank Cars or Highway Tanks

· Fight fire from maximum distance or use unmanned master stream devices or monitor nozzles.

· 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.

USSR (1976): 0.25 ppm

A harmful contamination of the air can be reached rather quickly on evaporation of this substance at 20 °C.

Mesityl oxide appears as a colorless, oily liquid with a pungent honey-like odor. Flash point 87 °F. Less dense than water and slightly soluble in water. Vapors heavier than air. Used in paint removers, as a solvent for plastics, and as an insect repellent.

Oily, colorless to light-yellow liquid with a peppermint- or honey-like odor; [NIOSH]

COLOURLESS VISCOUS LIQUID WITH CHARACTERISTIC ODOUR. DARKENS ON STANDING.

Colourless oily liquid; unpleasant grassy-green or pungent, acrylic odour

Oily, colorless to light-yellow liquid with a peppermint- or honey-like odor.

Oily, colorless to light-yellow liquid

... spearmint ...

COMMERCIAL GRADE EXHIBITS AN UNPLEASANT ODOR

Peppermint- or honey-like odor

OILY TASTE

266 °F at 760 mmHg (USCG, 1999)

130 °C at 760 mm Hg

130 °C @760 [mm Hg]

-51 °F (USCG, 1999)

MP: -41.5 °C (also reported as -59 °C); can be made to crystallize at low temp in petroleum ether

-41.5 °C

73 °F (USCG, 1999)

87 °F (31 °C) (Closed cup)

25 °C c.c.

3 % (NIOSH, 2024)

Sol in about 30 parts water; miscible with most org liq

Miscible in ethanol, ethyl ether

SLIGHTLY SOL IN PROPYLENE GLYCOL

In water, 28,900 mg/L at 20 °C

28.9 mg/mL at 20 °C

Solubility in water, g/100ml at 20 °C: 3.0 (moderate)

slightly soluble inwater; miscible in organic solvents

Miscible at room temperature (in ethanol)

0.853 at 68 °F (USCG, 1999) - Less dense than water; will float

0.8592 at 15 °C/4 °C

Bulk density = 7.1 lb/gal at 20 °C

0.87 g/cm³

Relative density of the vapour/air-mixture at 20 °C (air = 1): 1.03

0.862-0.868

0.853 at 68 °F

0.87 @ 20°C

(59 °F): 0.86

3.4 (Air = 1)

Relative vapor density (air = 1): 3.4

9 mmHg (NIOSH, 2024)

Highly flammable. Slightly soluble in water

Hydrocarbons, Aliphatic Unsaturated

Highly Flammable

Mixing MESITYL OXIDE in equal molar proportions with any of the following substances in a closed container caused the temperature and pressure to increase: 2-aminoethanol, chlorosulfonic acid, ethylene diamine, nitric acid, oleum, or sulfuric acid [NFPA 1991].

Mixing mesityl oxide and 2-aminoethanol /or chlorosulfonic acid or ethylene diamine or nitric acid or oleum or sulfuric acid/ in closed container caused temp and pressure to incr.

Oxidizers, acids.

... Attacks many plastics.

Oxidizers, acids

No indication of carcinogenicity to humans (not listed by IARC).

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

inhalation, ingestion, skin and/or eye contact

Cough. Sore throat. Shortness of breath. Headache. Dizziness. Drowsiness. Unconsciousness. Respiratory and cardiac arrest.

Dry skin. Redness. Pain.

Redness. Pain.

Abdominal cramps. Further see Inhalation.

irritation eyes, skin, mucous membrane; narcosis, coma; In Animals: liver, kidney damage; central nervous system effects

Eyes, skin, respiratory system, central nervous system, liver, kidneys

Neurotoxin - Acute solvent syndrome

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.

Nephrotoxin - The chemical is potentially toxic to the kidneys in the occupational setting.

Dermatotoxin - Skin burns.

Lacrimator (Lachrymator) - A substance that irritates the eyes and induces the flow of tears.

LC50 (rat) = 9,000 mg/m3/4H

LD50 Rat oral 655 mg/kg

LC50 Rat inhalation 1130 ppm/4 hr

LC50 Rat inhalation 9 g/cu m/4 hr

LD50 Mouse ip 354 mg/kg

For more Non-Human Toxicity Values (Complete) data for MESITYL OXIDE (12 total), please visit the HSDB record page.

Use of alcoholic beverages enhances the harmful effect.

Basic treatment: Establish a patent airway (oropharyngeal or nasopharyngeal airway, if needed). Suction if necessary. Watch for signs of respiratory insufficiency and assist ventilations if necessary. Administer oxygen by nonrebreather mask at 10 to 15 L/min. Monitor for pulmonary edema and treat if necessary ... Anticipate seizures and treat if necessary ... For eye contamination, flush eyes immediately with water. Irrigate each eye continuously with 0.9% saline (NS) during transport ... Do not use emetics. For ingestion, rinse mouth and administer 5 ml/kg up to 200 ml of water for dilution if the patient can swallow, has a strong gag reflex, and does not drool. /Turpentine, terpenes, and related compounds/

Advanced treatment: Consider orotracheal or nasotracheal intubation for airway control in the patient who is unconscious, has severe pulmonary edema, or is in severe respiratory distress. Positive- pressure ventilation techniques with a bag-valve-mask device may be beneficial. Consider drug therapy for pulmonary edema ... Monitor cardiac rhythm and treat arrhythmias as necessary ... Start IV administration of D5W /SRP: "To keep open", minimal flow rate/. Use 0.9% saline (NS) or lactated Ringer's (LR) if signs of hypovolemia are present. For hypotension with signs of hypovolemia, administer fluid cautiously. Watch for signs of fluid overload ...Treat seizures with diazepam or lorazepam ... Use proparacaine hydrochloride to assist eye irrigation ... /Turpentine, Terpenes, and related compounds/

Irrigate eyes with water. Wash contaminated areas of body with soap and water. Give oxygen if indicated.

/If ingested/ ... Rinse mouth. Give a slurry of activated charcoal in water to drink. Refer for medical attention.

/HUMAN EXPOSURE STUDIES/ A majority of individuals experienced eye irritation after 3 to 5 minutes of exposure at 25 ppm mesityl oxide with the addition of nasal irritation at 50 ppm. On the basis of an unpleasant taste that persisted in some cases for 3 to 6 hours after exposure and the nasal irritation experienced at 50 ppm, these workers suggested 25 ppm as the highest concentration, which would be satisfactory for an 8-hour day. The probable human response to 100 ppm of mesityl oxide was predicted to be eye and mucous membrane irritation accompanied by difficulty in breathing, headache, and vertigo.

/HUMAN EXPOSURE STUDIES/ Exposure to 50 to 100 ppm caused eye irritation and half of the test subjects experienced nasal irritation and pulmonary discomfort at 25 ppm.

/SIGNS AND SYMPTOMS/ Mesityl oxide (MO) can produce marked irritation and transient corneal injury to the eye. Occasional skin contact may produce some irritation; prolonged contact may produce dermatitis and, if the dose is high enough, systemic injury. MO ... can produce ... /CNS depression/ via inhalation exposure. Sublethal concentrations of the vapors may result in vascular congestion, which has been reported to occur primarily in the kidneys. The liver and lung are affected to a lesser degree. Death is generally attributed to its ... /CNS depressant/ action ... The penetrating odor and eye and nose irritation that occurs following exposure at low levels should prevent overexposure.

/SIGNS AND SYMPTOMS/ Mesityl oxide is a strong irritant both on contact with the liquid and in the vapor phase and can cause necrosis of the cornea. Short exposure /may cause CNS depression/ ...

For more Human Toxicity Excerpts (Complete) data for MESITYL OXIDE (11 total), please visit the HSDB record page.

/LABORATORY ANIMALS: Acute Exposure/ When doses of 0.5 mL were dropped on the skin of mice, marked irritation occurred within a few minutes and the animals became ataxic and narcotized within 15 min. This dose killed all ten animals in 3 to 9 hr. Applications of 0.1 mL to the backs of mice produced local irritation and excitement within 5 min; one of 10 animals died in 12 hr, but the others recovered.

/LABORATORY ANIMALS: Acute Exposure/ ... /It was foundthat / 12,000 ppm mesityl oxide (MO) killed rats and guinea pigs after 1 hr of exposure. Eight-hour exposures of rats to 2500, 1000, and 500 ppm killed 100, 68, and 30% of the test animals, respectively.

/LABORATORY ANIMALS: Acute Exposure/ ... Mice /were exposed/ to concentrations of 6,000 to 24,000 ppm mesityl oxide in air. Clinical signs of toxicity were ocular and nasal irritation, labored breathing, convulsions, /CNS depression/, vasodilation, cyanosis, and death. The time to death was concentration dependent, and ranged from 23 to 135 min.

/LABORATORY ANIMALS: Acute Exposure/ ... Groups of six male or female rats /were exposed/ to acute 4-hr exposures of increasing concentrations of mesityl oxide until two to four of the animals died within a 14-days observation period. They found that a concentration of 1,000 ppm was necessary to produce this mortality.

For more Non-Human Toxicity Excerpts (Complete) data for MESITYL OXIDE (29 total), please visit the HSDB record page.

Mesityl Oxide (CAS RN 141-79-7) was evaluated for repeated dose and reproductive effects in Sprague-Dawley rats in a study consisting of 4 phases: pre-mating (14 days), mating (1-14 days), gestation (21-22 days), and early lactation(4 days). Groups of 12 male and 12 female rats were exposed to target vapor concentrations of 0, 30, 100, or 300 ppm (mean chamber vapor concentrations: 0, 31, 103, or 302 ppm, respectively) for 6 hours/day, 7 days/ week. Females received a total of 36 to 49 exposures (through Day 20 of gestation) and males received 49 exposures. No mortality was observed in the adults. Clinical signs of toxicity were observed during exposure, including partially closed eyes (high-exposure) and temporary reduction in activity (high- and mid-exposure). All exposed animals exhibited an increased incidence of porphyrin nasal discharge post-exposure, and 3 high-exposure males exhibited sialorrhea. A treatment-related decrease in feed consumption, with a corresponding decrease in body weight and body weight gain were observed during pre-mating in all exposed males and females. Females exposed to 103 and 302 ppm (mid- and high-exposure) continued to exhibit these trends in feed consumption and body weight gain during the first week of gestation. Mating was confirmed in 12/12 control females and 12/12 high-exposure females, while 11/12 confirmed matings were noted in the low- and mid-exposure females. High-exposure females exhibited a significant reduction in the number of litters produced (7/12; p<=0.05). A second mating between high-exposure males (receiving 42 exposures) and unexposed females resulted in 10/12 dams producing litters, which was comparable to controls. No treatment-related changes were noted upon necropsy in any exposed animals. Histological examination of the reproductive organs revealed no treatment-related lesions in any exposed animals, however examination of the nasal passages revealed chronic focal inflamation and focal metaplasia of the respiratory and olfactory epithelium, and sero-cellular exudates. Differences in the length of gestation, number of pups per litter, ratio of males to females and mean pup weights were considered biologically insignificant. The lowest-observed-adverse-effect-level (NOAEL) based on feed consumption, body weights, body weight gain, and nasal passage histology was determined to be 31 ppm. The NOEL for reproductive toxicity under the test conditions was 103 ppm.

This submission contains a preliminary report from a study evaluating mesityl oxide (CAS RN 141-79-7) for repeated dose and reproductive effects in Sprague-Dawley rats. Groups of 12 male and 12 female rats were exposed to target vapor concentrations of 0, 30, 100, or 300 ppm (mean chamber vapor concentrations: 0, 31, 103, or 302 ppm, respectively) for 6 hours/day, 7 days/ week. Females received a total of 36 to 49 exposures (through Day 20 of gestation) and males received 49 exposures. No mortality was observed in the adults. Clinical signs of toxicity were not discussed. Mating, confirmed by the presence of a vaginal plug and/or the presence of sperm, was deemed successful in 12/12 control females and 12/12 high-exposure (300 ppm) females, while 11/12 confirmed matings were noted in the low- and mid-exposure females (30, and 100 ppm, respectively). The pregnancy index (number of litters delivered/number mated) for females exposed to 300 ppm was 7/12, or 58%. A second mating of high-exposure males (after 42 exposures) to unexposed females was conducted to further evaluate reproductive effects. As of this notification, the females of that second mating were in the third week of gestation. The males were euthanized on the day following the last exposure. Necropsy revealed no gross changes in the testes or epididymides or in testicular or epididymal weights. Histopathological evaluation was ongoing at the time this notice was filed.

Mesityl oxide (CAS RN 141-79-7) was evaluated for genetic toxicity in a mouse micronucleus assay, however, this submission contains only information concerning dose selection for the primary micronucleus assay. In the first of 3 studies, groups of male and female mice (3/sex/group; species and strain not reported) were administered 125, 250, or 500 mg/kg of the test substance in corn oil by intraperitoneal injection and were observed for a recovery period of up to 3 days. Mice in the 500 mg/kg group exhibited ataxia at 15 minutes post-dosing (females) and 30 minutes post-dosing (males). Lethargy was noted in all test groups (male and female). Recovery was complete at 7 hours post-dosing, and all animals survived a 3-day recovery period. Two additional studies were conducted in which groups (3/sex/group) were injected with 750 mg/kg (second study) and 875 or 1000 mg/kg (third study)and observed for up to 3 days. In study 2, 1 mortality occurred (female), while all animals exhibited ataxia and lethargy. At 7 hours, all survivors appeared normal, and all survived the 3-day observation period. At 1000 mg/kg, mortality was 100% within 40 minutes, and at 875 mg/kg, 2 males and females each were found dead within 48 hours. The remaining animals survived through the 3-day observation period. The LD50 under the conditions of this study was determined to be 850 mg/kg.

Mesityl oxide (CAS 141-79-7) was evaluated for the ability to induce micronuclei in mouse bone marrow polychromatic erythrocytes (PCE). The test material was administered to groups of Swiss CD-1 mice by intraperitoneal injection at 0, 170, 340, or 680 mg/kg, and groups (10/sex/group) at each dose level were sacrificed at 24, 48, and 72 hours after treatment. Negative control groups at each harvest time received corn oil only, while a positive control group received 40 mg cyclophosphamide/kg and were sacrificed at the 24 hour point only. Mortalities occurred in females receiving 680 mg/kg at the 24-hour harvest (1), the 48-hour harvest (2), and the 72-hour harvest (1) times. A statistically significant decrease in bone marrow was noted for male mice receiving 680 mg/kg of the test article. The test material did not induce a significant increase of micronucleated polychromatic erythrocytes (MNPCE) at any dose level compared to concurrent negative controls. It was concluded that the test material was negative for inducing the production of MNPCEs at dose levels causing mortalities among female mice and statistically significant bone marrow depression in male mice.

LD50 Carassius auratus (goldfish) 540 mg/L/24 hr /Conditions of bioassay not specified in source examined/

LD50 Carassius auratus (goldfish) 540 mg/L/24 hr /Conditions of bioassay not specified in source examined/

The substance is harmful to aquatic organisms.

Mesityl oxide's production and use in manufacturing methyl isobutyl ketone, and its use as an intermediate, solvent for nitrocellulose and vinyl chloride-vinyl acetate resins, additive, or mineral extractant may result in its release to the environment through various waste streams. Mesityl oxide's use as an insect repellent will result in its direct release to the environment. If released to air, a vapor pressure of 8.21 mm Hg at 25 °C indicates mesityl oxide will exist solely as a vapor in the atmosphere. Vapor-phase mesityl oxide will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals and ozone; the half-life for these reactions in air are estimated to be 4.9 hours and 1.4 hours, respectively. Mesityl oxide will also react with atmospheric nitrate with a half-life of 3.9 hours. Vapor-phase mesityl oxide undergoes direct photolysis with an experimental half-life and rate constant of 76.8 hrs and 8.75X10-3/hr, respectively. If released to soil, mesityl oxide is expected to have very high mobility based upon an estimated Koc of 15. Volatilization from moist soil surfaces is expected to be an important fate process based upon an estimated Henry's Law constant of 3.67X10-5 atm-cu m/mole. Mesityl oxide may volatilize from dry soil surfaces based upon its vapor pressure. Theoretical %BOD values of 74 and 30 from studies done with sewage inoculum suggest that biodegradation may be an important environmental fate process. If released into water, mesityl oxide is not expected to adsorb to suspended solids and sediment based upon the estimated Koc. Volatilization from water surfaces is expected to be an important fate process based upon this compound's estimated Henry's Law constant. Estimated volatilization half-lives for a model river and model lake are 17 hours and 11 days, respectively. An estimated BCF of 1.9 suggests the potential for bioconcentration in aquatic organisms is low. Hydrolysis is not expected to be an important environmental fate process since this compound lacks functional groups that hydrolyze under environmental conditions. Occupational exposure to mesityl oxide may occur through inhalation and dermal contact with this compound at workplaces where mesityl oxide is produced or used. Monitoring data indicate that the general population may be exposed to mesityl oxide via inhalation of ambient air, ingestion of food and drinking water, and dermal contact with insect repellents and other products containing mesityl oxide. (SRC)

Mesityl oxide was qualitatively identified in nectarines obtained from a local orchard in Winters, CA(1).

Mesityl oxide's production and use in manufacturing methyl isobutyl ketone(1), and its use as an intermediate(2), solvent for nitrocellulose(2) and vinyl chloride-vinyl acetate resins(2-3), additive(3), or mineral extractant(3) may result in its release to the environment through various waste streams(SRC). Mesityl oxide's use as an insect repellent(4) will result in its direct release to the environment(SRC).

TERRESTRIAL FATE: Based on a classification scheme(1), an estimated Koc value of 15(SRC), determined from a water solubility of 28,900 mg/L(2) and a regression-derived equation(3), indicates that mesityl oxide is expected to have very high mobility in soil(SRC). Volatilization of mesityl oxide from moist soil surfaces is expected to be an important fate process(SRC) given an estimated Henry's Law constant of 3.67X10-5 atm-cu m/mole(SRC), derived from its vapor pressure, 8.21 mm Hg(4), and water solubility(2). Mesityl oxide is expected to volatilize from dry soil surfaces(SRC) based upon its vapor pressure(4). Theoretical %BOD values of 74(5) and 30(6) from studies done with sewage inoculum suggest that biodegradation may be an important environmental fate process in soil(SRC).

AQUATIC FATE: Based on a classification scheme(1), an estimated Koc value of 15(SRC), determined from a water solubility of 28,900 mg/L(2) and a regression-derived equation(3), indicates that mesityl oxide is not expected to adsorb to suspended solids and sediment(SRC). Volatilization from water surfaces is expected(3) based upon an estimated Henry's Law constant of 3.67X10-5 atm-cu m/mole(SRC), derived from its vapor pressure, 8.21 mm Hg(4), and its water solubility(2). Using this Henry's Law constant and an estimation method(3), volatilization half-lives for a model river and model lake are 17 hours and 11 days, respectively(SRC). According to a classification scheme(5), an estimated BCF of 1.9(SRC), using a water solubility of 28,900 mg/L(2) and a regression-derived equation(6), suggests the potential for bioconcentration in aquatic organisms is low(SRC). Theoretical %BOD values of 74(7) and 30(8) from studies done with sewage inoculum suggest that biodegradation may be an important environmental fate process in water(SRC).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), mesityl oxide, which has a vapor pressure of 8.21 mm Hg at 25 °C(2), is expected to exist solely as a vapor in the ambient atmosphere. Vapor-phase mesityl oxide is degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals(SRC); the half-life for this reaction in air is estimated to be 4.9 hours(SRC), calculated from its rate constant of 7.86X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). The rate constant for the vapor-phase reaction of mesityl oxide with ozone has been estimated as 2X10-16 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). This corresponds to an atmospheric half-life of about 1.4 hours at an atmospheric concentration of 7X10+11 ozone molecules per cu cm(4). The rate constant for the vapor-phase reaction of mesityl oxide with nitrate has been estimated as 2.04X10-13 cu cm/molecule-sec at 25 °C(5). This corresponds to an atmospheric half-life of about 3.9 hours at an atmospheric concentration of 2.4X10+8 nitrate molecules per cu cm(6). Vapor-phase mesityl oxide undergoes direct photolysis with an experimental half-life and rate constant of 76.8 hrs and 8.75X10-3/hr, respectively(7).

AEROBIC: Using a standard BOD technique with sewage inoculum, a theoretical BOD of 74% was determined for mesityl oxide over a 5-day incubation period (1). Using a standard BOD technique with activated sewage sludge inoculum, a theoretical BOD of at least 30% was measured for mesityl oxide over a 14-day incubation period(2).

The rate constant for the vapor-phase reaction of mesityl oxide with photochemically-produced hydroxyl radicals has been estimated as 7.86X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 4.9 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). The rate constant for the vapor-phase reaction of mesityl oxide with ozone has been estimated as 2X10-16 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(1). This corresponds to an atmospheric half-life of about 1.4 hours at an atmospheric concentration of 7X10+11 ozone molecules per cu cm(2). The rate constant for the vapor-phase reaction of mesityl oxide with nitrate has been estimated as 2.04X10-13 cu cm/molecule-sec at 25 °C(3). This corresponds to an atmospheric half-life of about 3.9 hours at an atmospheric concentration of 2.4X10+8 nitrate molecules per cu cm(4). Mesityl oxide is not expected to undergo hydrolysis in the environment due to the lack of functional groups that hydrolyze under environmental conditions(5). Vapor-phase mesityl oxide undergoes direct photolysis with an experimental half-life and rate constant of 76.8 hrs and 8.75X10-3/hr, respectively(6).

An estimated BCF of 1.9 was calculated in fish for mesityl oxide(SRC), using a water solubility of 28,900 mg/L(1) and a regression-derived equation(2). According to a classification scheme(3), this BCF suggests the potential for bioconcentration in aquatic organisms is low(SRC).

The Koc of mesityl oxide is estimated as 15(SRC), using a water solubility of 28,900 mg/L(1) and a regression-derived equation(2). According to a classification scheme(3), this estimated Koc value suggests that mesityl oxide is expected to have very high mobility in soil.

The Henry's Law constant for mesityl oxide is estimated as 3.67X10-5 atm-cu m/mole(SRC) derived from its vapor pressure, 8.21 mm Hg(1), and water solubility, 28,900 mg/L(2). This Henry's Law constant indicates that mesityl oxide is expected to volatilize from water surfaces(3). Based on this Henry's Law constant, the volatilization half-life from a model river (1 m deep, flowing 1 m/sec, wind velocity of 3 m/sec)(3) is estimated as 17 hours(SRC). The volatilization half-life from a model lake (1 m deep, flowing 0.05 m/sec, wind velocity of 0.5 m/sec)(3) is estimated as 11 days(SRC). Mesityl oxide's estimated Henry's Law constant indicates that volatilization from moist soil surfaces may occur(SRC). The potential for volatilization of mesityl oxide from dry soil surfaces may exist(SRC) based upon its vapor pressure(1).

DRINKING WATER: Mesityl oxide was qualitatively detected in samples of drinking water taken from Cincinnati, OH waterworks on 10/17/78 and 1/14/80(1-3).

SURFACE WATER: Mesityl oxide was qualitatively detected in the Glatt River in Switzerland(1).

Exhaust from an automobile using various hydrocarbon fuels under simulated city conditions yielded concentrations of <0.1-1.5 ppm of mesityl oxide(1). Qualitatively detected in Lockport, IL oil refinery final effluent(2) and in advanced waste water treatment concentrates from Orange County and Lake Tahoe, CA(3-5). In a comprehensive survey of 46 industrial and publicly owned treatment works, mesityl oxide was qualitatively identified in effluents from various organic chemical manufacturing sites(6).

Mesityl oxide was qualitatively identified in Idaho Russet Burbank baked potatoes(1).

NIOSH (NOES Survey 1981-1983) has statistically estimated that 362 workers (34 of these are female) are potentially exposed to mesityl oxide in the US(1). Occupational exposure to mesityl oxide may occur through inhalation and dermal contact with this compound at workplaces where mesityl oxide is produced or used(SRC). Monitoring data indicate that the general population may be exposed to mesityl oxide via inhalation of ambient air, ingestion of food and drinking water, and dermal contact with insect repellents and other products containing mesityl oxide(SRC).

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational exposure or environmental contamination. Recycle any unused portion of the material for its approved use or return it to the manufacturer or supplier. Ultimate disposal of the chemical must consider: the material's impact on air quality; potential migration in soil or water; effects on animal, aquatic, and plant life; and conformance with environmental and public health regulations.

/GUIDE 129: FLAMMABLE LIQUIDS (Polar/Water-Miscible/Noxious)/ Fire or Explosion: HIGHLY FLAMMABLE: Will be easily ignited by heat, sparks or flames. Vapors may form explosive mixtures with air. Vapors may travel to source of ignition and flash back. Most vapors are heavier than air. They will spread along ground and collect in low or confined areas (sewers, basements, tanks). Vapor explosion hazard indoors, outdoors or in sewers. Those substances designated with a (P) may polymerize explosively when heated or involved in a fire. Runoff to sewer may create fire or explosion hazard. Containers may explode when heated. Many liquids are lighter than water.

/GUIDE 129: FLAMMABLE LIQUIDS (Polar/Water-Miscible/Noxious)/ Health: May cause toxic effects if inhaled or absorbed through skin. Inhalation or contact with material may irritate or burn skin and eyes. Fire will produce irritating, corrosive and/or toxic gases. Vapors may cause dizziness or suffocation. Runoff from fire control or dilution water may cause pollution.

/GUIDE 129: FLAMMABLE LIQUIDS (Polar/Water-Miscible/Noxious)/ Public Safety: CALL Emergency Response Telephone Number on Shipping Paper first. If Shipping Paper not available or no answer, refer to appropriate telephone number listed on the inside back cover. As an immediate precautionary measure, isolate spill or leak area for at least 50 meters (150 feet) in all directions. Keep unauthorized personnel away. Stay upwind. Keep out of low areas. Ventilate closed spaces before entering.

/GUIDE 129: FLAMMABLE LIQUIDS (Polar/Water-Miscible/Noxious)/ Protective Clothing: Wear positive pressure self-contained breathing apparatus (SCBA). Structural firefighters' protective clothing will only provide limited protection.

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

UN 1229; Mesityl oxide

IMO 3.3; Mesityl oxide

49 092 23; Mesityl oxide

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 Air Transport Association (IATA) Dangerous Goods Regulations are published by the IATA Dangerous Goods Board pursuant to IATA Resolutions 618 and 619 and constitute a manual of industry carrier regulations to be followed by all IATA Member airlines when transporting hazardous materials.

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.

Flammable Liquid

Symbol: Xn; R: 10-20/21/22; S: (2)-25

UN Hazard Class: 3; UN Pack Group: III