Diphenylmethane diisocyanate

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

H317: May cause an allergic skin reaction [Warning Sensitization, Skin]

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

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

H334: May cause allergy or asthma symptoms or breathing difficulties if inhaled [Danger Sensitization, respiratory]

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

H351: Suspected of causing cancer [Warning Carcinogenicity]

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

P203, P233, P260, P261, P264, P264+P265, P271, P272, P280, P284, P302+P352, P304+P340, P305+P351+P338, P317, P318, P319, P321, P332+P317, P333+P317, P337+P317, P342+P316, P362+P364, P403, P403+P233, P405, and P501 (click each P-code to see the statement)

H315 (100%): Causes skin irritation [Warning Skin corrosion/irritation]

H317 (100%): May cause an allergic skin reaction [Warning Sensitization, Skin]

H319 (99.9%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]

H332 (90.1%): Harmful if inhaled [Warning Acute toxicity, inhalation]

H334 (100%): May cause allergy or asthma symptoms or breathing difficulties if inhaled [Danger Sensitization, respiratory]

H335 (96%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

H351 (99%): Suspected of causing cancer [Warning Carcinogenicity]

H373 (88.9%): May causes damage to organs through prolonged or repeated exposure [Warning Specific target organ toxicity, repeated exposure]

Aggregated GHS information provided per 1939 reports by companies from 54 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.

This chemical does not meet GHS hazard criteria for 2.6% (37 of 1404) of reports.

H315 (97.4%): Causes skin irritation [Warning Skin corrosion/irritation]

H317 (97.4%): May cause an allergic skin reaction [Warning Sensitization, Skin]

H319 (97.4%): Causes serious eye irritation [Warning Serious eye damage/eye irritation]

H330 (31.4%): Fatal if inhaled [Danger Acute toxicity, inhalation]

H332 (66%): Harmful if inhaled [Warning Acute toxicity, inhalation]

H334 (97.4%): May cause allergy or asthma symptoms or breathing difficulties if inhaled [Danger Sensitization, respiratory]

H335 (92%): May cause respiratory irritation [Warning Specific target organ toxicity, single exposure; Respiratory tract irritation]

H351 (94.3%): Suspected of causing cancer [Warning Carcinogenicity]

H373 (95.4%): May causes damage to organs through prolonged or repeated exposure [Warning Specific target organ toxicity, repeated exposure]

P203, P233, P260, P261, P264, P264+P265, P271, P272, P280, P284, P302+P352, P304+P340, P305+P351+P338, P316, P317, P318, P319, P320, P321, P332+P317, P333+P317, P337+P317, P342+P316, P362+P364, P403, P403+P233, P405, and P501 (click each P-code to see the statement)

Aggregated GHS information provided per 1404 reports by companies from 40 notifications to the ECHA C&L Inventory. Each notification may be associated with multiple companies.

Reported as not meeting GHS hazard criteria per 37 of 1404 reports by companies.

There are 39 notifications provided by 1367 of 1404 reports by companies with hazard statement code(s).

H320: Causes eye irritation [Warning Serious eye damage/eye irritation]

H330: Fatal if inhaled [Danger Acute toxicity, inhalation]

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]

P233, P260, P261, P264, P264+P265, P270, P271, P272, P280, P284, P302+P352, P304+P340, P305+P351+P338, P308+P316, P316, P319, P320, P321, P332+P317, P333+P317, P337+P317, P342+P316, P362+P364, P403, P403+P233, P405, and P501 (click each P-code to see the statement)

P260, P261, P264, P264+P265, P271, P272, P280, P284, P302+P352, P304+P340, P305+P351+P338, P316, P320, P321, P332+P317, P333+P317, P337+P317, P362+P364, P403+P233, P405, and P501 (click each P-code to see the statement)

P233, P260, P261, P264, P264+P265, P270, P271, P272, P280, P284, P302+P352, P304+P340, P305+P351+P338, P316, P319, P320, P321, P332+P317, P333+P317, P337+P317, P342+P316, P362+P364, P403, P403+P233, P405, and P501 (click each P-code to see the statement)

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

Remove contaminated clothes. Rinse skin with plenty of water or shower. 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 for medical attention .

EYES: First check the victim for contact lenses and remove if present. Flush victim's eyes with water or normal saline solution for 20 to 30 minutes while simultaneously calling a hospital or poison control center. Do not put any ointments, oils, or medication in the victim's eyes without specific instructions from a physician. IMMEDIATELY transport the victim after flushing eyes to a hospital even if no symptoms (such as redness or irritation) develop.

SKIN: IMMEDIATELY flood affected skin with water while removing and isolating all contaminated clothing. Gently wash all affected skin areas thoroughly with soap and water. IMMEDIATELY call a hospital or poison control center even if no symptoms (such as redness or irritation) develop. IMMEDIATELY transport the victim to a hospital for treatment after washing the affected areas.

INHALATION: IMMEDIATELY leave the contaminated area; take deep breaths of fresh air. IMMEDIATELY call a physician and be prepared to transport the victim to a hospital even if no symptoms (such as wheezing, coughing, shortness of breath, or burning in the mouth, throat, or chest) develop. Provide proper respiratory protection to rescuers entering an unknown atmosphere. Whenever possible, Self-Contained Breathing Apparatus (SCBA) should be used; if not available, use a level of protection greater than or equal to that advised under Protective Clothing.

INGESTION: If the victim is conscious and not convulsing, give 1 or 2 glasses of water to dilute the chemical and IMMEDIATELY call a hospital or poison control center. Generally, the induction of vomiting is NOT recommended outside of a physician's care due to the risk of aspirating the chemical into the victim's lungs. However, if the victim is conscious and not convulsing and if medical help is not readily available, consider the risk of inducing vomiting because of the high toxicity of the chemical ingested. Ipecac syrup or salt water may be used in such an emergency. IMMEDIATELY transport the victim to a hospital. If the victim is convulsing or unconscious, do not give anything by mouth, ensure that the victim's airway is open and lay the victim on his/her side with the head lower than the body. DO NOT INDUCE VOMITING. IMMEDIATELY transport the victim to a hospital. (NTP, 1992)

(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 156 [Substances - Toxic and/or Corrosive (Combustible / Water-Sensitive)]:

Note: Most foams will react with the material and release corrosive/toxic gases. CAUTION: For Acetyl bromide (UN1716), use CO2 or dry chemical only.

SMALL FIRE: CO2, dry chemical, dry sand, alcohol-resistant foam.

LARGE FIRE: Water spray, fog or alcohol-resistant foam. FOR CHLOROSILANES, DO NOT USE WATER; use alcohol-resistant foam. If it can be done safely, move undamaged containers away from the area around the fire. 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. (ERG, 2024)

Use powder, carbon dioxide.

Carbon dioxide or dry chemical.

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. /Methylene diphenyl diisocyanate/

Where there is a fire involving isocyanates, carbon dioxide or powder extinguishers must be employed. Firemen must be equipped with self-contained breathing apparatus. /Isocyanates/

Excerpt from ERG Guide 156 [Substances - Toxic and/or Corrosive (Combustible / Water-Sensitive)]:

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)

Evacuate danger area! Consult an expert! Personal protection: chemical protection suit including self-contained breathing apparatus. Sweep spilled substance into covered sealable containers. Carefully collect remainder. Then store and dispose of according to local regulations.

VENTILATE AREA OF SPILL OR LEAK. FOR SMALL QUANTITIES, ABSORB ON PAPER TOWELS. ... BURN THE PAPER IN SUITABLE LOCATION AWAY FROM COMBUSTIBLE MATERIALS. LARGE QUANTITIES CAN BE COLLECTED & ATOMIZED IN SUITABLE COMBUSTION CHAMBER EQUIPPED WITH APPROPRIATE EFFLUENT GAS CLEANING DEVICE. DISPOSAL METHODS: 1. BY ABSORBING ON VERMICULITE, DRY SAND, EARTH OR A SIMILAR MATERIAL & DISPOSING IN A SECURED SANITARY LANDFILL. 2. BY ATOMIZING IN SUITABLE COMBUSTION CHAMBER EQUIPPED WITH APPROPRIATE EFFLUENT GAS CLEANING DEVICE.

Environmental considerations - land spill: Dig a pit, pond, lagoon, holding area to contain liquid or solid material. 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. /Methylene diphenyl diisocyanate/

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. Remove trapped material with suction hoses. /Methylene diphenyl diisocyanate/

Decontamination of spilled isocyanates and disposal of isocyanate waste are best conducted by using aqueous ammonia (3-8% concentrated ammonia solution in 90-95% water with 0.2-5% liquid detergent) or aqueous sodium carbonate (5-10% sodium carbonate in 90-95% water and 0.2-5% liquid detergent). An alcoholic solution (50% ethanol, isopropyl alcohol, or butanol; 45% water; and 5% concentrated ammonia) may be preferred because of the low miscibility of isocyanates with water. /Isocyanates/

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity 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 and plant life; and conformance with environmental and public health 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.

SRP: Contaminated protective clothing should be segregated in such a manner so that there is no direct personal contact by personnel who handle, dispose, or clean the clothing. The completeness of the cleaning procedures should be considered before the decontaminated protective clothing is returned for reuse by the workers. Contaminated clothing should not be taken home at the end of shift, but should remain at employee's place of work for cleaning.

SRP: The scientific literature for the use of contact lenses by industrial workers is inconsistent. The benefits or detrimental effects of wearing contact lenses depend not only upon the substance, but also on factors including the form of the substance, characteristics and duration of the exposure, the uses of other eye protection equipment, and the hygiene of the lenses. However, there may be individual substances whose irritating or corrosive properties are such that the wearing of contact lenses would be harmful to the eye. In those specific cases, contact lenses should not be worn. In any event, the usual eye protection equipment should be worn even when contact lenses are in place.

The worker should immediately wash the skin when it becomes contaminated.

Work clothing that becomes wet or significantly contaminated should be removed and replaced.

For more Preventive Measures (Complete) data for 4,4'-Methylenediphenyl Diisocyanate (11 total), please visit the HSDB record page.

Excerpt from ERG Guide 156 [Substances - Toxic and/or Corrosive (Combustible / Water-Sensitive)]:

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 damaged containers or spilled material unless wearing appropriate protective clothing. Stop leak if you can do it without risk. A vapor-suppressing foam may be used to reduce vapors. FOR CHLOROSILANES, use alcohol-resistant foam to reduce vapors. DO NOT GET WATER on spilled substance or inside containers. Use water spray to reduce vapors or divert vapor cloud drift. Avoid allowing water runoff to contact spilled material. Prevent entry into waterways, sewers, basements or confined areas.

SMALL SPILL: Cover with DRY earth, DRY sand or other non-combustible material followed with plastic sheet to minimize spreading or contact with rain. Use clean, non-sparking tools to collect material and place it into loosely covered plastic containers for later disposal. (ERG, 2024)

Separated from food and feedstuffs and incompatible materials. See Chemical Dangers. Cool. Dry. Keep in the dark.

Isocyanates are transported in railroad tank cars, tank trucks, tanks in ships, containers, and drums. They are stored in steel tanks and processed in steel equipment. For long-term storage stainless steel is recommended. To avoid contamination by atmospheric moisture, a dry air or inert gas blanket is essential. /Isocyanates/

0.05 [mg/m3], inhalable fraction[German Research Foundation (DFG)]

3.12 [ppm]

0.15 [mg/m3]

5.0 [mg/m3]

55 [mg/m3]

0.090 [mg/m3]

0.005 ppm (0.05 mg/m³)

0.020 ppm (0.2 mg/m³) [10 minutes]

TWA 0.05 mg/m3 (0.005 ppm) C 0.2 mg/m3 (0.020 ppm) [10-minute]

0.02 ppm (0.2 mg/m³)

C 0.2 mg/m3 (0.02 ppm)

75 mg/m3 (NIOSH, 2024)

Excerpts from Documentation for IDLHs: Basis for original (SCP) IDLH: The chosen IDLH is based on an analogy with toluene diisocyanate, which has an IDLH of 10 ppm. [Note: A concentration of 10 ppm methylene bisphenyl isocyanate is equivalent to about 100 mg/m3.]

75 mg/cu m

75 mg/m³

75 mg/m3

See: 101688

0.05 [mg/m3]

8 hr Time Weighted Avg (TWA): 0.005 ppm

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.

0.005 ppm as TWA.

0.005 ppm [1985]

(inhalable fraction): 0.05 mg/m

ERPG-1: Not appropriate - one hour exposure limit: 1 = mild transient health effects or objectionable odor [AIHA]

ERPG-2: 5 mg/m3 - one hour exposure limit: 2 = impaired ability to take protective action [AIHA]

ERPG-3: 55 mg/m3 - one hour exposure limit: 3 = life threatening health effects [AIHA]

Emergency Response Planning Guidelines (ERPG): ERPG(1) 0.2 mg/cu m (no more than mild, transient effects) for up to 1 hr exposure; ERPG(2) 2 mg/cu m (without serious, adverse effects) for up to 1 hr exposure; ERPG(3) 25 mg/cu m (not life threatening) up to 1 hr exposure.

Evaporation at 20 °C is negligible; a harmful concentration of airborne particles can, however, be reached quickly when dispersed.

Lachrymation. The substance is irritating to the eyes, skin and respiratory tract. The substance may cause effects on the lungs. This may result in impaired functions.

Repeated or prolonged contact may cause skin sensitization. Repeated or prolonged inhalation may cause asthma.

Excerpt from NIOSH Pocket Guide for Methylene bisphenyl isocyanate:

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

Eyes: PREVENT EYE CONTACT - Wear appropriate eye protection to prevent eye contact.

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

Remove: WHEN WET OR CONTAMINATED - Work clothing that becomes wet or significantly contaminated should be removed and replaced.

Change: DAILY - Workers whose clothing may have become contaminated should change into uncontaminated clothing before leaving the work premises. (NIOSH, 2024)

MASK OR RESPIRATOR OF TYPE APPROVED BY USA BUREAU OF MINES (ABOVE 135 °C); CLEAN RUBBER GLOVES; CHEMICAL GOGGLES; CLEAN WATERPROOF OR FRESHLY LAUNDERED PROTECTIVE CLOTHING (COVERALLS, RUBBER BOOTS, CAP, ETC).

Wear appropriate personal protective clothing to prevent skin contact.

Wear appropriate eye protection to prevent eye contact.

Respirator Recommendations: Up to 0.5 mg/cu m: [Table#4083]

Diphenylmethane-4,4-diisocyanate is a light yellow colored solid. It is not soluble in water. It may be toxic by ingestion, inhalation, or skin absorption. If in a solution it may or may not burn depending on the nature of the material and/or the solvent. It is used to make plastics.

CBI; Liquid; Other Solid; Liquid

Dry Powder; Other Solid; Liquid; Wet Solid; Large Crystals; Liquid; Liquid; Liquid; Other Solid

White to light-yellow, odorless flakes. [Note: A liquid above 99 degrees F.]; [NIOSH]

Polymeric MDI: Dark amber viscous liquid; Pure 4,4'-MDI: White waxy solid; [CPS&Q: RARs - Final Report] Light to dark yellow liquid with a mild musty odor; mp = 15-20 deg C; [Bayer Material Science MSDS]

WHITE-TO-PALE-YELLOW CRYSTALS OR FLAKES.

White to light-yellow, odorless flakes.

White to light-yellow, odorless flakes. [Note: A liquid above 99 °F.]

Light-yellow, fused solid

Crystals

White to light yellow flakes [Note: A liquid above 99 degrees F]

Odorless

381 to 390 °F at 5 mmHg (NTP, 1992)

BP: 196 °C at 5 mm Hg

at 100kPa: 314 °C

99 °F (NTP, 1992)

425 °F (NTP, 1992)

396 °F (OPEN CUP)

196 °C c.c.

Insoluble (NTP, 1992)

Soluble in acetone, benzene, kerosene, and nitrobenzene

Solubility in water: reaction

1.2 at 68 °F (USCG, 1999) - Denser than water; will sink

Density: 1.197 g/cu cm at 70 °C

Relative density (water = 1): 1.2

1.23 (Solid at 77 °F) 1.19 (Liquid at 122 °F)

1.197 @ 70°C

Relative vapor density (air = 1): 8.6

5e-06 mmHg at 77 °F (NIOSH, 2024)

0.000005 [mmHg]

0.000004 [mmHg]

5.0X10-6 mm Hg at 25 °C

Vapor pressure at 20 °C: negligible

0.000005 mmHg at 77 °F

(77 °F): 0.000005 mmHg

When heated to decomposition it emits toxic fumes of /nitrogen oxides and sulfur oxides/.

Odor Threshold Low: 0.39 [mg/m3]

Odor threshold from AIHA

Odor Threshold Low: 0.4 [ppm]

Odor threshold from IUCLID

It is not soluble in water.

Isocyanates and Isothiocyanates

Isocyanates and thioisocyanates, such as DIPHENYLMETHANE-4,4'-DIISOCYANATE, are incompatible with many classes of compounds, reacting exothermically to release toxic gases. Reactions with amines, aldehydes, alcohols, alkali metals, ketones, mercaptans, strong oxidizers, hydrides, phenols, and peroxides can cause vigorous releases of heat. Acids and bases initiate polymerization reactions in these materials. Some isocyanates react with water to form amines and liberate carbon dioxide. Base-catalysed reactions of isocyanates with alcohols should be carried out in inert solvents. Such reactions in the absence of solvents often occur with explosive violence, [Wischmeyer(1969)].

Strong alkalis, acids, alcohol [Note: Polymerizes at 450 degrees F].

Strong alkalis, acids, alcohol [Note: Polymerizes at 450 °F.]

IDENTIFICATION AND USE: This chemical exists as a colorless or light yellow fused solid. 4,4'-Methylenediphenyl diisocyanate (MDI) is miscible in water, and soluble in acetone, benzene, kerosene, and nitrobenzene. The product is used to make rigid and semi-rigid polyurethane foams. Pure MDI is distilled from the reaction mixture and is used for reaction injection molding, thermoplastic elastomers, and adhesives. HUMAN EXPOSURE AND TOXICITY: MDI is irritating to skin, eyes, and respiratory passages. Nose and throat irritation has also been observed. A few cases of alveolitis have been reported in workers exposed to MDI vapors. Contact allergy and allergic contact eczema have been reported in workers exposed to MDI. Cases of asthmatic breathing have been observed in workers. Lung fibrosis is also been observed in workers exposed to MDI. Children living in proximity of an accidental MDI release had signs of sore throat, dizziness, nausea and breathing difficulties MDI is an allergic sensitizer. Workers in occupational settings have the potential for inhalation or skin contact with particles of MDI. There is inadequate evidence for the carcinogenicity of MDI in humans. ANIMAL STUDIES: There is limited evidence in experimental animals for the carcinogenicity of MDI. MDI has low oral toxicity in rats. Repeated doses of MDI for 5 days in corn oil produced slight spleen enlargement in rats. In male and female rats exposed to polymeric MDI aerosol there was increased incidences of pulmonary adenomas in high dose males. Accumulation of alveolar macrophages containing polymeric MDI were associated with retractile yellowish material, localized fibrosis and alveolar duct epithelialization and increased alveolar bronchiolization were observed in the lungs of the high dose group. A 2 yr inhalation study using a mixture of MDI and higher weight oligomers showed both male and female rats had treatment related histological changes in the nasal cavity, lungs and lymph nodes. In female rats exposed by inhalation to MDI on days 6-15 of gestation, there was a slight increase in asymmetric sternbrae at the highest dose but no adverse effect was observed on maternal weight gain, number of corpea lutea, implantation sites, pre and post- implantation loss, fetal or placental weight, gross abnormalities or degree of ossification. MDI was tested for mutagenicity in Salmonella typhimurium strains TA98, TA100, TA1535 and TA1537 in the presence or absence of metabolic activation. The chemical was negative for mutagenicity. MDI in the micronucleus assay was negative for mutagenicity.

Cyanide is an inhibitor of cytochrome c oxidase in the fourth complex of the electron transport chain (found in the membrane of the mitochondria of eukaryotic cells). It complexes with the ferric iron atom in this enzyme. The binding of cyanide to this cytochrome prevents transport of electrons from cytochrome c oxidase to oxygen. As a result, the electron transport chain is disrupted and the cell can no longer aerobically produce ATP for energy. Tissues that mainly depend on aerobic respiration, such as the central nervous system and the heart, are particularly affected. Cyanide is also known produce some of its toxic effects by binding to catalase, glutathione peroxidase, methemoglobin, hydroxocobalamin, phosphatase, tyrosinase, ascorbic acid oxidase, xanthine oxidase, succinic dehydrogenase, and Cu/Zn superoxide dismutase. Cyanide binds to the ferric ion of methemoglobin to form inactive cyanmethemoglobin. (L97)

Methylene Diphenyl Diisocyanate (monomeric MDI) and polymeric MDI (PMDI)

Respiratory

6 x 10 ^-4 mg/m^3

Evaluation: There is inadequate evidence for the carcinogenicity of 4,4'-methylenediphenyl diisocyanate or polymeric 4,4'-methylenediphenyl diisocyanate in humans. There is limited evidence in experimental animals for the carcinogenicity of a mixture containing monomeric and polymeric 4,4'-methylenediphenyl diisocyanate. Overall evaluation: 4,4'-Methylenediphenyl diisocyanate (industrial preparation) is not classifiable as to its carcinogenicity in humans (Group 3).

WEIGHT OF EVIDENCE CHARACTERIZATION: Under U.S. EPA's 1996 Guidelines for Carcinogenic Risk Assessment, monomeric MDI or polymeric MDI (PMDI) would be classified as not classifiable or a Group D chemical. Under U.S. EPA's 1996 Proposed Guidelines for Carcinogenic Risk Assessment, the carcinogenic potential of MDI/PMDI would be characterized as "cannot be determined, but for which there is suggestive evidence that raises concern for carcinogenic effects" on the following basis. The increased incidence of pulmonary adenomas in male (6/60) and female (2/59) Wistar rats [strain Cpu:WU] and one pulmonary adenocarcinoma in a male rat, all exposed to the highest concentration in a lifetime chronic inhalation study involving PMDI, suggest that PMDI has tumorigenic potential. However, the tumorigenic results, coupled with evidence that methylene diphenyl aniline (MDA) a known animal carcinogen and the principal reaction product of MDI, is found in blood of MDI-exposed rats and nonhydrolyzed urine of PMDI/MDI-exposed humans increases concern about the carcinogenic potential of PMDI/MDI. The available human evidence is inadequate to describe the carcinogenic potential of PMDI/MDI. HUMAN CARCINOGENICITY DATA: Inadequate. ANIMAL CARCINOGENICITY DATA: Limited.

4,4'-Methylenediphenyl diisocyanate

Group 3: Not classifiable as to its carcinogenicity to humans

Volume 19: (1979) Some Monomers, Plastics and Synthetic Elastomers, and Acrolein

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)

Volume 71: (1999) Re-evaluation of Some Organic Chemicals, Hydrazine and Hydrogen Peroxide (Part 1, Part 2, Part 3)

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

Exposure to high levels of cyanide for a short time harms the brain and heart and can even cause coma, seizures, apnea, cardiac arrest and death. Chronic inhalation of cyanide causes breathing difficulties, chest pain, vomiting, blood changes, headaches, and enlargement of the thyroid gland. Skin contact with cyanide salts can irritate and produce sores. (L96, L97)

The substance can be absorbed into the body by inhalation.

inhalation, ingestion, skin and/or eye contact

Oral (L96) ; inhalation (L96) ; dermal (L96)

Headache. Nausea. Shortness of breath. Sore throat.

Redness.

irritation eyes, nose, throat; resp sensitization; cough, pulmonary secretions, chest pain, dyspnea (breathing difficulty); asthma

Cyanide poisoning is identified by rapid, deep breathing and shortness of breath, general weakness, giddiness, headaches, vertigo, confusion, convulsions/seizures and eventually loss of consciousness. (L96, L97)

Eyes, respiratory system

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

Skin Sensitizer - An agent that can induce an allergic reaction in the skin.

Asthma - Reversible bronchoconstriction (narrowing of bronchioles) initiated by the inhalation of irritating or allergenic agents.

Fibrogenic - Inducing tissue injury and fibrosis (scarring).

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

IRIS Current

HEAST Current

LC50 (rat) = 369 mg/m3/4H

LC50 (rat) = 369 mg/m3/4hr

LD50: 369 mg/m3 over 4 hours (Inhalation, Rat) (T13)

LC50 Rat (male) inhalation 369 mg/cu m/4 hr

LC50 Rat (female) inhalation 380 mg/cu m/4 hr

Antidotes to cyanide poisoning include hydroxocobalamin and sodium nitrite, which release the cyanide from the cytochrome system, and rhodanase, which is an enzyme occurring naturally in mammals that combines serum cyanide with thiosulfate, producing comparatively harmless thiocyanate. Oxygen therapy can also be administered. (L97)

Immediate first aid: Ensure that adequate decontamination has been carried out. If patient is not breathing, start artificial respiration, preferably with a demand-valve resuscitator, bag-valve-mask device, or pocket mask, as trained. Perform CPR as necessary. Immediately flush contaminated eyes with gently flowing water. Do not induce vomiting. If vomiting occurs, lean patient forward or place on left side (head-down position, if possible) to maintain an open airway and prevent aspiration. Keep patient quiet and maintain normal body temperature. Obtain medical attention. /Isocyanates, aliphatic thiocyanates, and related compounds/

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 ... . Monitor for shock and treat if necessary ... . Monitor for 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 patent can swallow, has a strong gag reflex, and does not drool. Administer activated charcoal ... . /Isocyanates, aliphatic thiocyanates, 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 ... . Consider administering a beta agonist such as albuterol for severe bronchospasm ... . Monitor cardiac rhythm and treat arrhythmias if 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. Consider vasopressors if patient is hypotensive with a normal fluid volume. Watch for signs of fluid overload ... . Treat seizures with diazepam or lorazepam ... . Use proparacaine hydrochloride to assist eye irrigation ... . /Isocyanates, aliphatic thiocyanates, and related compounds/

Emergency and supportive measures: After acute high-intensity inhalation exposure, maintain on open airway, give bronchodilators as needed for wheezing, and observe for 8-12 hours for pulmonary edema. Once airway hyperactivity has been documented, further exposure to isocyanate is contraindicated. Involve public health or OSHA agencies to determine whether other workers are at increased risk through improper workplace controls. /Isocyanates/

For more Antidote and Emergency Treatment (Complete) data for 4,4'-Methylenediphenyl Diisocyanate (6 total), please visit the HSDB record page.

8.50e+05

3.60e+06

6.30e-01

2.60e+00

5.00e+00

6.00e-04

Volatile

2.60e+06

1.10e+07

1.90e+00

7.90e+00

4,4'-Methylenediphenyl diisocyanate's production and use in polyurethane resins and spandex fibers and in bonding rubber to rayon and nylon may result in its release to the environment through various waste streams. If released to air, a vapor pressure of 5.0X10-6 mm Hg at 25 °C indicates 4,4'-methylenediphenyl diisocyanate will exist in both the vapor and particulate phases in the atmosphere. Vapor-phase 4,4'-methylenediphenyl diisocyanate will be degraded in the atmosphere by reaction with photochemically-produced hydroxyl radicals; the half-life for this reaction in air is estimated to be 11 hrs. Particulate-phase 4,4'-methylenediphenyl diisocyanate will be removed from the atmosphere by wet or dry deposition. 4,4'-Methylenediphenyl diisocyanate does not contain chromophores that absorb at wavelengths >290 nm, and therefore is not expected to be susceptible to direct photolysis by sunlight. If released to water or moist soil, 4,4'-methylenediphenyl diisocyanate is not expected to leach or adsorb to solids due to its rapid hydrolysis. Biodegradation data in soil or water were not available. Since 4,4'-methylenediphenyl diisocyanate reacts with water to form amines and urea, accumulation in the food chain should be low or non-existent. Occupational exposure to 4,4'-methylenediphenyl diisocyanate occurs through inhalation of vapors and aerosols and through dermal contact with this compound and other compounds containing 4,4'-methylenediphenyl diisocyanate. Use data indicate that the general population may be exposed to 4,4'-methylenediphenyl diisocyanate via inhalation and dermal contact with consumer products containing this compound. (SRC)

4,4'-Methylenediphenyl diisocyanate's production and use in the preparation of polyurethane resin and spandex fibers and in bonding rubber to rayon and nylon(1) may result in its release to the environment through various waste streams(SRC).

TERRESTRIAL FATE: When monomeric 4,4'-methylenediphenyl diisocyanate is handled as a liquid (melting point 38 °C), it will solidify on contact with soil(1). 4,4'-Methylenediphenyl diisocyanate reacts readily with water(1-5). If released to soil, agglomerations of 4,4'-methylenediphenyl diisocyanate react with water to form a hard crust of inert, water-insoluble material comprised of polyureas(1); the polyurea crusts can entrap monomeric 4,4'-methylenediphenyl diisocyanate and prevent further contact with water, thereby increasing the persistence time(1). 4,4'-Methylenediphenyl diisocyanate is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 5.0X10-6 mm Hg(6). Biodegradation data in soil were not available(SRC, 2012).

AQUATIC FATE: 4,4'-Methylenediphenyl diisocyanate was added to a model marine system and a model river to simulate spill situations(1,2); 4,4'-methylenediphenyl diisocyanate concentrations fell to a maximum of 5% of initial value within one day(1,2). Spills or agglomerations of 4,4'-methylenediphenyl diisocyanate react with water to form a hard crust of inert, water-insoluble material comprised of polyureas(1); the polyurea crusts can entrap monomeric 4,4'-methylenediphenyl diisocyanate and prevent further contact with water, thereby increasing the persistence time(1). Small aquatic releases of 4,4'-methylenediphenyl diisocyanate will hydrolyze rapidly in water with an estimated half-life of a few minutes to a few hours(3-5). Biodegradation data in water were not available(SRC, 2012).

ATMOSPHERIC FATE: According to a model of gas/particle partitioning of semivolatile organic compounds in the atmosphere(1), 4,4'-methylenediphenyl diisocyanate, which has a vapor pressure of 5.0X10-6 mm Hg at 25 °C(2), is expected to exist in both the vapor and particulate phases in the ambient atmosphere(SRC). Vapor-phase 4,4'-methylenediphenyl diisocyanate 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 11 hours(SRC), calculated from its rate constant of 1.2X10-11 cu cm/molecule-sec at 25 °C(SRC) determined using a structure estimation method(3). Reaction with atmospheric water vapor(4) may increase the atmospheric degradation rate several fold(SRC). Particulate-phase 4,4'-methylenediphenyl diisocyanate will be removed from the atmosphere by wet and dry deposition(SRC). 4,4'-Methylenediphenyl diisocyanate does not contain chromophores that absorb at wavelengths >290 nm(5), and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC).

The rate constant for the vapor-phase reaction of 4,4'-methylenediphenyl diisocyanate with photochemically-produced hydroxyl radicals has been estimated as 1.2X10-11 cu cm/molecule-sec at 25 °C(SRC) using a structure estimation method(1). This corresponds to an atmospheric half-life of about 11 hours at an atmospheric concentration of 5X10+5 hydroxyl radicals per cu cm(1). 4,4'-Methylenediphenyl diisocyanate does not contain chromophores that absorb at wavelengths >290 nm(2), and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC).

When monomeric 4,4'-methylenediphenyl diisocyanate comes in contact with water in a spill situation, it reacts with the water to form a hard crust of inert, water-insoluble material comprised mostly of polyureas(1,2). 4,4'-Methylenediphenyl diisocyanate is reported to hydrolyze rapidly in water(3,4); however, a hydrolysis rate constant specific to 4,4'-methylenediphenyl diisocyanate was not available. Based on available data and analogy to other isocyanates, the hydrolysis half-life is on the order of a few minutes to a few hours(5). Reaction with water is complex and usually involves several mechanisms(1); an initial unstable intermediate (acid) is formed that decomposes to the amine with liberation of carbon dioxide, and the amine can react with more 4,4'-methylenediphenyl diisocyanate to form a polyurea(1). Atmospheric chamber studies with the similar compound TDI (toluene diisocyanate) have shown that vapor-phase degradation increased from 15% to about 20% per hour as a result of OH radical attack(6); the 15% per hour rate occurred in the dark (no hydroxyl radical) with a relative humidity of 7-70%(6); therefore, reaction with water vapor in air may be more important than OH radical reaction for 4,4'-methylenediphenyl diisocyanate but this could also be a surface reaction in the chamber(SRC).

Isocyanates hydrolyze readily in water to yield a carbamic acid, which decarboxylates to produce CO2 and an amine; the latter immediately reacts with more isocyanate to yield a disubstituted urea(1). /Isocyanates/

4,4'-Methylenediphenyl diisocyanate hydrolyzes rapidly in aqueous solution(1-3); therefore, bioconcentration will not be an important environmental fate process(SRC). Exposure of carp to 0.00001% concentrations of 4,4'-methylenediphenyl diisocyanate for an eight week period resulted in no bioaccumulations(4).

4,4'-Methylenediphenyl diisocyanate hydrolyzes rapidly in aqueous solution(1-3); therefore, leaching and adsorption to moist soil and sediment will not be an important environmental fate process(SRC).

4,4'-Methylenediphenyl diisocyanate hydrolyzes rapidly in aqueous solution(1-3); therefore, volatilization from water and moist soil will not be an important environmental process(SRC). 4,4'-Methylenediphenyl diisocyanate is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 5.0X10-6 mm Hg(4).

4,4'-Methylenediphenyl diisocyanate emission levels of <0.02 to 1.0 mg/kg core material were detected from foundry molds using polyurethane binders(1).

4,4'-Methylenediphenyl diisocyanate emission from commercial composite boards cured with polyurethane glue was below the detection limit of 20 parts/trillion. For aluminum and wood substrates cured with glue, the compound was detected at 60 part/trillion in the first 8 hours of sampling but below the detection limit thereafter(1).

... WHEN MDI PREPN ARE SPRAYED OUT OF DOORS OR IN MINE SHAFTS, PERSONS 40 M OR MORE DOWNWIND MAY BE AFFECTED BY UNREACTED ISOCYANATE IN DROPLETS CARRIED BY AIR CURRENT.

EARLY INDUSTRIAL EXPERIENCE IN HANDLING MDI /METHYLENEBIS(4-PHENYLISOCYANATE)/ REVEALED NO CASES OF SKIN IRRITATION. MDI ADHERES FIRMLY TO SKIN, HOWEVER, & IRRITATION MAY BE INCR OR PRODUCED BY ATTEMPTS AT REMOVAL.

... THE PHYSICAL CHARACTERISTIC OF LOW BUT SIGNIFICANT VAPOR PRESSURE PRESENTS BOTH A VAPOR & PARTICULATE /(DROPLET)/ EXPOSURE IN ONE OF THE CURRENT APPLICATION MDI NAMELY, IN FOAM- OR FILM-COATING OF SURFACES BY SPRAY-GUN TECHNIQUES. MEASURING ENVIRONMENTAL CONTAMINATION DURING THE FOAM APPLICATION SHOWED LEVELS OF TOTAL MDI AS HIGH AS 5 MG/CU M. MORE THAN 95% OF HIGH SAMPLES WERE PARTICULATES OF RESPIRABLE SIZE RANGE, COUNTS WERE FROM 2 TO 8 MILLION PARTS/CU FT. MDI VAPOR CONCN AT BREATHING ZONE DURING APPLICATION DID NOT EXCEED 0.02 PPM (0.2 MG/CU M).

According to the 2006 TSCA Inventory Update Reporting data, the number of persons reasonably likely to be exposed in the industrial manufacturing, processing, and use of 4,4'-methylenediphenyl diisocyanate is 1000 or greater; the data may be greatly underestimated(1).

For more Probable Routes of Human Exposure (Complete) data for 4,4'-Methylenediphenyl Diisocyanate (6 total), please visit the HSDB record page.

SRP: The most favorable course of action is to use an alternative chemical product with less inherent propensity for occupational harm/injury/toxicity 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 and plant life; and conformance with environmental and public health 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.

Unbreakable packaging. Put breakable packaging into closed unbreakable container. Do not transport with food and feedstuffs.

Symbol: Xn; R: 20-36/37/38-42/43; S: (1/2)-23-36/37-45; Note: C