Dicyclohexylmethan-4,4'-diisocyanat

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)

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: 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. Quality assurance to ascertain the completeness of the cleaning procedures should be implemented before the decontaminated protective clothing is returned for reuse by the workers. Contaminated clothing should not be taken home at end of shift, but should remain at employee's place of work for cleaning.

SRP: The scientific literature for the use of contact lenses in industry is conflicting. The benefit 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.

0.005 [ppm]

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 [1985]

0.16 [mg/m3]

3.2 [mg/m3]

19 [mg/m3]

0.01 ppm (0.11 mg/m³)

C 0.01 ppm (0.11 mg/m3)

Excerpt from NIOSH Pocket Guide for Methylene bis(4-cyclohexylisocyanate):

Respirator Recommendations: Up to 0.1 ppm: [Table#6802]

Respirator Recommendations: Up to 0.25 ppm: [Table#6803]

Respirator Recommendations: Up to 0.5 ppm: [Table#6804]

Respirator Recommendations: Up to 1 ppm: [Table#6805]

For more Personal Protective Equipment (PPE) (Complete) data for METHYLENE BIS(4-CYCLOHEXYLISOCYANATE) (9 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)

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: Isocyanates hydrolyze readily in moist soil(1); therefore, adsorption and volatilization of methylene bis(4-cyclohexylisocyanate) are not expected to be an important environmental fate process(SRC). Methylene bis(4-cyclohexylisocyanate) is not expected to volatilize from dry soil surfaces(SRC) based upon an estimated vapor pressure of 2.3X10-5 mm Hg at 25 °C(SRC), determined from a fragment constant method(2). A 0% of theoretical BOD using activated sludge in the Japanese MITI test(3) suggests that biodegradation is an important environmental fate process in soil(SRC).

AQUATIC FATE: Isocyanates hydrolyze readily in water(1); therefore, adsorption to solids and sediment, volatilization and bioconcentration of methylene bis(4-cyclohexylisocyanate) are not expected to be an important environmental fate process(SRC). A 0% of theoretical BOD using activated sludge in the Japanese MITI test(2) suggests that biodegradation is 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), methylene bis(4-cyclohexylisocyanate), which has an estimated vapor pressure of 2.3X10-5 mm Hg at 25 °C(SRC), determined from a fragment constant method(2), will exist in both the vapor and particulate phases in the ambient atmosphere. Vapor-phase methylene bis(4-cyclohexylisocyanate) 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 5 hours(SRC), calculated from its rate constant of 2.6X10-11 cu cm/molecule-sec at 25 °C(SRC) that was derived using a structure estimation method(3). Particulate-phase methylene bis(4-cyclohexylisocyanate) may be removed from the air by wet or dry deposition(SRC). Methylene bis(4-cyclohexylisocyanate) does not contain chromophores that absorb at wavelengths >290 nm(4), and therefore is not expected to be susceptible to direct photolysis by sunlight(SRC).

inhalation, ingestion, skin and/or eye contact

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

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)

irritation eyes, skin, respiratory system; skin, resp sensitization; chest tightness, dyspnea (breathing difficulty), cough, dry throat, wheezing, pulmonary edema; skin blisters

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)

/SIGNS AND SYMPTOMS/ Exposure of humans to methylene bis(4-cyclohexylisocyanate) has resulted in skin sensitization but only rarely in pulmonary sensitization.

/SIGNS AND SYMPTOMS/ Eleven out of fifteen workers who were first exposed to the substance showed allergic and non-allergic skin reaction. Six suffered from vertigo with and without headaches and four developed a decrease of the obstructive lung function, tachycardia and hypotension (EKG normally).

/CASE REPORTS/ Organic di-isocyanates are used widely in industry. The concomitant respiratory complications are well-known. Cutaneous problems precipitated by skin contact with these chemicals are less well recognized. Allergic contact dermatitis caused by exposure to di-cyclohexylmethane 4,4'-di-isocyanate has been demonstrated in a factory where it was used to form a surface-coating polyurethane. Attention to hygiene methods may have reduced the incidence of cases.

/CASE REPORTS/ The aliphatic diisocyanate dicyclohexylmethane-4,4'-diisocyanate (DMDI) is known to be a strong cutaneous sensitizer. /Investigators/ report a 27-year-old woman who developed a severe eczematous eruption on the arms, trunk, and abdomen within 2 weeks of employment at a company using the product Chem-Dec 808 isocyanate (containing 40-70% weight per weight DMDI). Patch testing was performed with the North American screening series, an isocyanate series, and 1% Chem-Dec 808 isocyanate. At day 7, a +++ reaction to Chem-Dec 808 isocyanate and a ++ reaction to the aromatic isocyanate diphenylmethane-4,4'-diisocyanate were observed. DMDI has strong sensitizing potential and requires rigorous safety monitoring in the workplace.

For more Human Toxicity Excerpts (Complete) data for METHYLENE BIS(4-CYCLOHEXYLISOCYANATE) (6 total), please visit the HSDB record page.

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. Cyclohexane, 1,1'-methylenebis(4-isocyanato)- is included on this list. Effective date: 6/1/87; Sunset date: 6/1/97.