Diphenylmethan-4,4'-diisocyanat

Hazardous Air Pollutants (HAPs)

Reactive agents - 1st degree

Plastics & Rubber -> Diisocyanates

Plastics & Rubber -> Diisocyanates

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

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

Light-yellow, fused solid

Crystals

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

Insoluble (NTP, 1992)

Soluble in acetone, benzene, kerosene, and nitrobenzene

Solubility in water: reaction

0.2%

425 °F (NTP, 1992)

396 °F (OPEN CUP)

196 °C c.c.

390 °F

390 °F

381 to 390 °F at 5 mmHg (NTP, 1992)

BP: 196 °C at 5 mm Hg

at 100kPa: 314 °C

597 °F

597 °F

99 °F (NTP, 1992)

37 °C

37 °C

99 °F

37 °C

99 °F

Danger

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

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)

Danger

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

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)

Chemical: Benzene, 1,1'-methylenebis[4-isocyanato-

Chemical: Benzene, 1,1'-methylenebis[isocyanato-

Hazard Traits - Dermatotoxicity; Immunotoxicity; Musculoskeletal Toxicity; Respiratory Toxicity

Hazard Traits - Dermatotoxicity; Immunotoxicity; Respiratory Toxicity

Benzene, 1,1'-methylenebis[isocyanato- is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Benzene, 1,1'-methylenebis[isocyanato- are required to report information about their production and use of this chemical to the EPA under the Toxic Substances Control Act (TSCA). (40 eCFR Part 711)

Benzene, 1,1'-methylenebis[4-isocyanato- is listed on the EPA's Chemical Data Reporting (CDR) system. Manufacturers and importers of Benzene, 1,1'-methylenebis[4-isocyanato- are required to report information about their production and use of this chemical to the EPA under the Toxic Substances Control Act (TSCA). (40 eCFR Part 711)

IMAP assessments - Methylenediphenyl diisocyanates: Human health tier II assessment

IMAP assessments - Benzene, 1,1'-methylenebis[4-isocyanato-: Environment tier I assessment

Special Hazards of Combustion Products: Toxic vapors are generated when heated.

Combustible. Gives off irritating or toxic fumes (or gases) in a fire.

The commercial form of 4,4'-methylenediphenyl diisocyanate (MDI) is used to produce polyurethane foams. Acute (short-term) inhalation of high concentrations of MDI may cause sensitization and asthma in humans. Acute dermal contact with MDI has induced dermatitis and eczema in workers. MDI has been observed to irritate the skin and eyes of rabbits. Chronic (long-term) inhalation exposure to MDI has been shown to cause asthma, dyspnea, and other respiratory impairments in workers. Respiratory effects have also been observed in animals. No adequate information is available on the reproductive, developmental, or carcinogenic effects of MDI in humans. EPA has classified MDI as a Group D, not classifiable as to human carcinogenicity.

Solid form can cause reddening of skin if left on clothes. [CHRIS] Cases of hypersensitivity pneumonitis (TDI HP and MDI HP) have been reported. [Rom, p. 388-90] Tear drawing. Can cause skin sensitization and asthma; [ICSC] Biological monitoring of exposure to 1,5-naphthalene diisocyanate and 4,4'-methylenediphenyl diisocyanate. [PMID 16506043] See Methylenediphenyl diisocyanate.

This CAS refers not only to isomeric mixtures but also all the specific isomers including those with unique CAS numbers; A skin, eye, and respiratory tract irritant; Allergic contact dermatitis, contact urticaria, asthma, and hypersensitivity pneumonitis reported from occupational exposure; Long term occupational inhalation exposure has demonstrated decreased ventilatory function and respiratory symptoms even at levels below current guidelines; [CPS&Q: RARs - Final Report] Causes contact urticaria; [Kanerva, p. 219] Reacts slowly with water evolving carbon dioxide; An irritant; May cause skin and respiratory sensitization; Inhalation overexposure may cause bronchitis, bronchial spasm, and pulmonary edema; [Bayer Material Science MSDS] See Methylene bisphenyl isocyanate.

WOOLRICH PF; TOXICOLOGY, INDUSTRIAL HYGIENE AND MEDICAL CONTROL OF TDI, MDI AND PMPPI; AM IND HYG ASSOC J 43 (2): 89 (1982). A REVIEW OF THE TOXICOLOGY, INDUSTRIAL HYGIENE, & MEDICAL CONTROL OF MDI IS PRESENTED.

Canadian Centre for Occupational Health and Safety; Methylene Bisphenyl isocyanate and Polymethylene Polyphenyl Isocyanate p.1-20 (1987). The hazards of methylene-bisphenyl-isocyanate and polymethylene-polyphenyl-isocyanate are discussed.

National Occupational Health and Safety Commission (Worksafe Australia); Isocyanates p.1-16 (1990). Safety guide to the identification and safe use of isocyanates in the workplace.

Banks DE et al; Isocyanate-Induced Respiratory Disease; Annals of Allergy 57 (6): 389-96 (1986). Clinical features of isocyanate induced asthma, adverse respiratory effects associated with methylene-diphenyl-diisocyanate exposure, adverse respiratory effects due to exposure to other isocyanate compounds, pathophysiology of isocyanate asthma, and challenge testing and the diagnosis of isocyanate asthma are discussed.

U.S. Environmental Protection Agency's Integrated Risk Information System (IRIS) for Methylene diphenyl diisocyanate (monomeric MDI) and polymeric MDI (PMDI) (101-68-8; 9016-87-9) Toxicological Review in Adobe PDF.[Available from, as of February, 1998: http://www.epa.gov/iris/]

Section 8(a) of TSCA requires manufacturers of this chemical substance to report preliminary assessment information concerned with production, exposure, and use to EPA as cited in the preamble in 51 FR 41329. Effective date: 10/29/90; Reporting date: 12/27/90.

Pursuant to section 8(d) of TSCA, EPA promulgated a model Health and Safety Data Reporting Rule. The section 8(d) model rule requires manufacturers, importers, and processors of listed chemical substances and mixtures to submit to EPA copies and lists of unpublished health and safety studies. Benzene, 1,1'-methylenebis(4-isocyanato)- is included on this list. Effective date: 6/1/87; Sunset date: 6/1/97.

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

Use powder, carbon dioxide.

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.

(General first aid procedures)

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

3.12 [ppm]

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/

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/

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.

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.

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.

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)

Nervous

Eyes, respiratory system

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)

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).

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.

The substance can be absorbed into the body by inhalation.

inhalation, ingestion, skin and/or eye contact

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

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)

Headache. Nausea. Shortness of breath. Sore throat.

Redness.

Pain.

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)

The following link will take the user to the National Toxicology Program (NTP) Test Agent Search Results page, which tabulates all of the "Standard Toxicology & Carcinogenesis Studies", "Developmental Studies", and "Genetic Toxicity Studies" performed with this chemical. Clicking on the "Testing Status" link will take the user to the status (i.e., in review, in progress, in preparation, on test, completed, etc.) and results of all the studies that the NTP has done on this chemical.[Available from: http://ntp-apps.niehs.nih.gov/ntp_tox/index.cfm?fuseaction=ntpsearch.searchresults&searchterm=101-68-8]

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

Nervous

6 x 10 ^-4 mg/m^3

Section 8(a) of TSCA requires manufacturers of this chemical substance to report preliminary assessment information concerned with production, exposure, and use to EPA as cited in the preamble in 51 FR 41329. Effective date: 10/29/90; Reporting date: 12/27/90.

Pursuant to section 8(d) of TSCA, EPA promulgated a model Health and Safety Data Reporting Rule. The section 8(d) model rule requires manufacturers, importers, and processors of listed chemical substances and mixtures to submit to EPA copies and lists of unpublished health and safety studies. Benzene, 1,1'-methylenebis(4-isocyanato)- is included on this list. Effective date: 6/1/87; Sunset date: 6/1/97.

This action promulgates standards of performance for equipment leaks of Volatile Organic Compounds (VOC) in the Synthetic Organic Chemical Manufacturing Industry (SOCMI). The intended effect of these standards is to require all newly constructed, modified, and reconstructed SOCMI process units to use the best demonstrated system of continuous emission reduction for equipment leaks of VOC, considering costs, non air quality health and environmental impact and energy requirements. Methylene diphenyl diisocyanate is produced, as an intermediate or a final product, by process units covered under this subpart.

Listed as a hazardous air pollutant (HAP) generally known or suspected to cause serious health problems. The Clean Air Act, as amended in 1990, directs EPA to set standards requiring major sources to sharply reduce routine emissions of toxic pollutants. EPA is required to establish and phase in specific performance based standards for all air emission sources that emit one or more of the listed pollutants. Methylenebis(4-phenylisocyanate) is included on this list.

Persons in charge of vessels or facilities are required to notify the National Response Center (NRC) immediately, when there is a release of this designated hazardous substance, in an amount equal to or greater than its reportable quantity of 5000 lb or 2270 kg. The toll free number of the NRC is (800) 424-8802. The rule for determining when notification is required is stated in 40 CFR 302.4 (section IV. D.3.b).

After inhlalation exposure of female Wistar rats to 4,4'-methylene diisocyanate aerosols (0.26, 0.70 and 2.06 mg/cu m chronically for three and 12 months), 4,4'methylenedianiline and N-acetyl-4,4'-methylenedianiline were the major urinary metabolites. Hemoglobin adducts of these metabolites were also detected. The dose-response relationships for hemoglobin adducts and urinary metabolites were non-linear over this dose range. The amounts of 4,4'-methylenedianiline and, to a lesser extent, N-acetyl-4,4'-methylenedianiline found in urine correlated well with the corresponding amount determined as hemoglobin adducts for all dose groups. Similar results were obtained with rats exposed for three and 12 months, indicating that a steady state had been reached by three months. Hemoglobin adducts from rats after a one-week recovery period decreased by approximately 40% for all dosed groups, suggesting that erythrocytes containing modified hemoglobin have a shorter lifespan.

This work was undertaken to investigate the usefulness of diisocyanate-related protein adducts in blood samples as biomarkers of occupational exposure to toluene diisocyanate (TDI; 2,4- and 2,6-isomers) and 4,4'-methylenediphenyl diisocyanate (MDI). Quantification of adducts as toluene diamines (TDAs) and methylenedianiline (MDA) was performed on perfluoroacylated derivatives by gas chromatography-mass spectrometry (GC-MS/MS) in negative chemical ionisation mode. TDI-derived adducts were found in 77% of plasma and in 59% of globin samples from exposed workers manufacturing flexible polyurethane foam. The plasma levels ranged from 0.003 to 0.58 nmol mL(-1) and those in globin from 0.012 to 0.33 nmol g(-1). The 2,6-isomer amounted to about two-thirds of the sum concentration of TDA isomers. MDI-derived adducts were detected in 3.5% of plasma and in 7% of globin samples from exposed workers manufacturing rigid polyurethane foam. A good correlation was found between the sum of TDA isomers in urine and that in plasma. The relationship between globin adducts and urinary metabolites was ambiguous. Monitoring TDI-derived TDA in plasma thus appears to be an appropriate method for assessing occupational exposure. Contrary to TDI exposure, adducts in plasma or globin were not useful in assessing workers' exposure to MDI. An important outcome of the study was that no amine-related adducts were detected in globin samples from TDI- or MDI-exposed workers, alleviating concerns that TDI or MDI might pose a carcinogenic hazard.

Methylenedianiline (MDA) could be identified in pooled samples of hydrolyzed plasma and urine from 10 workers exposed to MDI (it is unclear whether thermal breakdown was involved). MDA could be identified in hydrolyzed hemoglobin from 10 of 26 workers exposed to MDI (all but three <0.3 ppb; values for the other three were 1.0, 1.8 and 2.9 ppb). After alkaline extraction there were measurable amounts of acetyl-MDA (AcMDA) and lesser amounts of MDA in urine from 18 of the 26, MDA alone in 4 samples, and neither substance in 4. After acid hydrolysis the MDA levels were on average about 1/3 higher that the total of AcMDA and MDA in the previous analysis. The levels of hemoglobin adducts had no correlation to metabolites in urine. In a polyurethane production facility where air concentrations of MDI were usually below the detection limit, measurable amounts of 4,4'-MDA (0.035-0.83 pmol/mL) and AcMDA (0.13-7.61 pmol/mL) could be found in urine in 15 of 20 workers after alkaline extraction, and MDA values were 6.5 times higher after acid hydrolysis. MDA was found as hemoglobin adducts in all the examined workers, and one worker also had adducts of AcMDA. Plasma levels of 4,4'-MDA ranged from 0.25 to 5.4 pmol/mL, up to 120 fmol/mg of which was covalently bound to albumin.

Cyanide is rapidly alsorbed through oral, inhalation, and dermal routes and distributed throughout the body. Cyanide is mainly metabolized into thiocyanate by either rhodanese or 3-mercaptopyruvate sulfur transferase. Cyanide metabolites are excreted in the urine. (L96)

Following topical administration of (14)C 4,4'methylenediphenyl diisocyanate in acetone to female Wistar rats, 20% of the administered dose was eliminated in the feces within 24 hours, while less than 1% appeared in the urine.

Polyurethanes (PU) are polymers made with diisocyanates such as MDI (4,4'-methylene diphenyl diisocyanate) and TDI (2,4-toluene diisocyanate and 2,6-toluene diisocyanate). Investigations have been undertaken with MDI and TDI to assess dermal uptake and resulting systemic exposure. Absorption, distribution and excretion of MDI was studied in rats using a single dermal administration of (14)C-MDI dissolved in acetone at nominal 165 mg/kg body weight and 15 mg/kg bw (4.0 and 0.4 mg/sq cm) and intradermal injection of (14)C-MDI dissolved in corn oil at nominal 1.4 mg/kg bw. Dermal absorption of (14)C-MDI (at both doses) was low; at or below 1% of the applied dose. Considerable amounts of the applied radioactivity were found at the application site which could not be washed off. By intradermal administration of (14)C-MDI approximately 66% of applied radioactivity remained at the application site with approximately 26% recovered in excreta, cage wash, tissues and carcass. The absorption, distribution and excretion of 2,4-TDI was studied in rats following a single dermal administration of radiolabelled (14)C-2,4-TDI at nominal 350 mg/kg body weight (12 mg/sq cm). Dermal absorption of (14)C-2,4-TDI was at or below 1% of the applied dose. Considerable amounts of the applied radioactivity were found at the application site which could not be washed off. In summary the results show that dermal uptake of MDI and TDI is very low. Due to the chemical reactivity of isocyanates it can be expected that small amounts which might be absorbed will react with tissue constituents directly at the exposed skin area, or will be converted to adducts with biomacromolecules or to biologically inactive oligoureas. Overall it is concluded that, following dermal exposure to MDI and TDI, systemic exposures and resulting toxicity, other than the known sensitization, can be expected to be very low. In addition studies were performed with dermal application of unlabelled 2,4 and 2,6 TDI to check the availability and fate of this chemical on rat skin surface and to assess possible tissue damage. These experiments showed that unchanged test material can be detected on rat skin for up to 8 hr if not washed off. Dermal treatment with 2,4 or 2,6 TDI was associated with irritation with increased severity over a 48 hr period after washing with a decontaminant solution.

The commercial form of MDI is primarily used to produce polyurethane foams.

Pattern of use in 1974: coatings (28%); elastomers (22%); thermoplastic resins (22%); spandex fibers (19%); millable gums (9%); [HSDB] Occupational asthma reported in foundry; [Malo] Allergic contact dermatitis in shoemakers and other workers using glues; [Marks] Used in spray-on truck bed liners; [Reference #2]

Molding and Core Making [Category: Foundry]

Preparing and mounting animal skins (taxidermy) [Category: Hobbies]

Used in the furniture, car, shoe, carpet, refrigerators and freezers, textile, coatings, and construction industries; [IUCLID] Used primarily in the manufacture of rigid polyurethane foams; Other uses include coatings, adhesives, sealants, elastomers, paints, footwear, (semi) flexible and thermoplastic polyurethane foams, polyurethane fibers, and to make particle board and foundry mould cores; [CPS&Q: RARs - Final Report]

Molding and Core Making [Category: Foundry]

(1974) 3.18-3.63X10+10 GRAMS (POLYMERIC FORM)

5 percent of production

(1975) 1.00X10+6 grams

Negligible

2023: 100,000,000 - <250,000,000 lb

2023: 700,000,000 - <850,000,000 lb

(1974) 3.63-4.54X10+9 GRAMS (CONSUMPTION)

(1988) 3.65X10+8 lb

This is a high volume chemical with production exceeding 1 million pounds annually in the U.S.

Capacity: 1,970 million lbs/yr of polymeric and pure diphenylmethane 4,4'-diisocyanate

28% AS AN INT FOR POLYURETHANE COATINGS; 22% AS AN INT FOR POLYURETHANE ELASTOMERS; 22% AS AN INT FOR POLYURETHANE THERMOPLASTIC RESINS; 19% AS AN INT FOR POLYURETHANE SPANDEX FIBERS; 9% AS AN INT FOR POLYURETHANE MILLABLE GUMS (1974)

Rigid polyurethane foam, 80 percent (construction, 50 percent; refrigeration, 12 percent; packaging, 8 percent; tank and pipe insulation, 3 percent; other foam uses, including transportation, marine flotation and furniture, 7 percent); reaction-injection molding (RIM) applications, 13 percent; cast elastomers, 2 percent; miscellaneous pure and polymeric MDI uses, including thermoplastic resins and foundry core binders, 5 percent.

Demand: (1997) 1.33 billion pounds; (1998) 1.34 billion pounds; (2002) 1.51 billion pounds.

Pigment

Surface modifier

Monomers

Other

The production of PMDI /polymeric methylenediphenyl diisocyanate/ involves condensation of aniline with formaldehyde in the presence of hydrochloric acid to give oligomeric di- and polyamines that are phosgenated without further need of purification. The percentage distribution of the homologues and isomers of MDA /methylenedianiline/ depends on the ratio of aniline to formaldehyde, the acid concentration, and the reaction conditions. Monomeric MDI is obtained from PMDI by continuous thin-film distillation.

Pure diphenylmethane 4,4'-diisocyanate formed through a two-step process beginning with the condensation reaction between aniline and formaldehyde, yielding diphenylmethane diamine. A subsequent phosgenation gives the aromatic isocyanate MDI.

4,4'-Methylenediphenyl diisocyanate blocked with, for example, phenol is preferred in some applications.

MDI usually occurs as a mixture of several isomers and oligomers: one common mixture is approximately 30-40% diphenylmethane-4,4'-diisocyanate, 2.5-4.0% diphenylmethane-2,4'-diisocyanate, 0.1-0.2 % diphenylmethane-2,2'- diisocyanate, and the remaining 50-60% oligomers.

Information on 105 consumer products that contain Methylene bisphenyl diisocyanate (MDI) in the following categories is provided:

Information on 13 consumer products that contain Urethane prepolymer Diphenylmethane-diisocyanate in the following categories is provided:

Transportation Equipment Manufacturing

All Other Basic Organic Chemical Manufacturing

Benzene, 1,1'-methylenebis[4-isocyanato-: ACTIVE

Benzene, 1,1'-methylenebis[isocyanato-: ACTIVE

The market split is roughly 80 percent polymeric and 20 percent pure MDI.