4,4′-Methylenebis (2-chloroaniline) (MOCA)


4,4′-methylenebis(2- chloroaniline) or MOCA, is an aromatic amine used as a curing agent in the manufacture of castable polyurethane products, with the chemical formula C13H12Cl2N2. It creates chemical reactions that bond other molecules in relatively stable complex structures and produces a tough abrasion-resistant polymer. Pure MOCA is a colourless crysalline solid, but it is usually made and used as yellow, tan, or brown pellets. If MOCA is heated above 205°C it may decompose by itself. It has no odour or taste. [1,2]

Uses [3]

MOCA is used to make polyurethane products that are a significant component of many common appliances. These are widely used in such items as gear systems in modern office and home appliances, sporting goods, mouldings for motor vehicle body parts and military equipment. The compound is commonly used as a coating to set other glues, plastics and adhesives. Its main purpose is to act as a curing agent for other polyurethane and elastomer compounds. It is essential for creating chemical reactions that bond other molecules in relatively stable complex structures, which comprise these compounds.

In the Environment [4]

  • MOCA enters the environment from the disposal of solid waste from manufacturing plants that use it.
  • It doesn’t dissolve in water easily.
  • MOCA sticks strongly to soil particles.
  • It is not likely to enter groundwater.
  • MOCA is not likely to evaporate from soil or water.
  • It is broken down by sunlight in air and by microscopic organisms in soil or water.
  • Levels of MOCA can build up in the roots of vegetables grown in contaminated soil.

Sources of Emission & Routes of Exposure [3]

Sources of Emission

  • Industry sources: Released from industries producing and manufacturing polyurethane products, for example components for household appliances, cameras, computers, motor vehicle component manufacturers specialised motor car body shops.
  • Diffuse sources: Small quantities may be present in air or upon surfaces in the vicinity of plants that manufacture polyurethane products.
  • Natural sources: Not known to occur in nature.
  • Transport sources: No mobile sources.
  • Consumer products: Present as a component in relatively stable compounds which comprise polyurethane products such as sporting goods, footwear, computers, cameras, gear and bearing systems in household appliances, motor vehicle body parts and mouldings.

Routes of Exposure

The main routes of exposure to MOCA are by direct contact with the skin or eyes or the inhalation of dust and other particles to which it is attached.

Health Effects [5]

Acute Effects

In one case, an accidental acute exposure of a worker to MOCA, symptoms of gastrointestinal distress, transitory kidney damage, and burning face and eyes were reported. Tests involving acute exposure of rats, mice, and guinea pigs have shown MOCA to have moderate to high acute toxicity from oral exposure.

Chronic Effects

No information is available on the chronic effects of MOCA in humans. Animal studies have reported effects on the lung, liver, and kidney from chronic oral exposure to MOCA. EPA has not established a Reference Concentration (RfC) for MOCA, however, it has calculated a provisional Reference Dose (RfD) of 0.0007 milligrams per kilogram body weight per day (mg/kg/d) for MOCA based on liver and kidney effects in dogs.

Reproductive/Developmental Effects

No information is available on the reproductive or developmental effects of MOCA in humans or animals.

Cancer Risk

In one epidemiologic study of 200 workers exposed to MOCA, 3 men were diagnosed with bladder cancer. However, there were no controls in this study and no information on the exposure concentrations. Animal studies have reported that MOCA produces tumours of the liver, lung, urinary bladder, and mammary gland from oral exposure. MOCA has a chemical structure similar to benzidine, a known human bladder carcinogen, and to a potent animal carcinogen, 3,3′-dichlorobenzidine. EPA has classified MOCA as a Group B2, probable human carcinogen.

Safety [6]

First Aid Measures

  • Eye Contact: Check for and remove any contact lenses. In case of contact, immediately flush eyes with plenty of water for at least 15 minutes. Get medical attention.
  • Skin Contact: In case of contact, immediately flush skin with plenty of water. Cover the irritated skin with an emollient. Remove contaminated clothing and shoes. Wash clothing before reuse. Thoroughly clean shoes before reuse. Get medical attention.
  • Serious Skin Contact: Wash with a disinfectant soap and cover the contaminated skin with an anti-bacterial cream. Seek immediate medical attention.
  • Inhalation: If inhaled, remove to fresh air. If not breathing, give artificial respiration. If breathing is difficult, give oxygen. Get medical attention.
  • Ingestion: Do NOT induce vomiting unless directed to do so by medical personnel. Never give anything by mouth to an unconscious person. If large quantities of this material are swallowed, call a physician immediately. Loosen tight clothing such as a collar, tie, belt or waistband.

Fire & Explosion Hazards

  • MOCA may be combustible at high temperature.
  • Slightly flammable to flammable in presence of heat.
  • Non-flammable in presence of shocks.
  • Slightly explosive in presence of open flames and sparks.
  • Non-explosive in presence of shocks.
  • For small fires, dry chemical powder should be used.
  • For large fires, water spray, fog or foam should be used. Do not use water jet.
  • Fine dust dispersed in air in sufficient concentrations, and in the presences of an ignition source is a potential dust explosion hazard.

Exposure Controls and Personal Protection

Engineering Controls

Use process enclosures, local exhaust ventilation, or other engineering controls to keep airborne levels below recommended exposure limits. If user operations generate dust, fume or mist, use ventilation to keep exposure to airborne contaminants below the exposure limit.

Personal Protective Equipment

The following personal protective equipment is recommended when handling MOCA:

  • Splash goggles;
  • Lab coat;
  • Dust respirator (be sure to use an approved/certified respirator or equivalent);
  • Gloves

Personal Protection in Case of a Large Spill:

  • Splash goggles;
  • Full suit;
  • Dust respirator;
  • Boots;
  • Gloves;
  • A self-contained breathing apparatus should be used to avoid inhalation of the product.
  • Suggested protective clothing might not be sufficient; consult a specialist BEFORE handling this product.


United States [4]

  • EPA: Environmental Protection Agency has classified MOCA as a hazardous waste that must meet specific disposal requirements. The EPA requires that spills or accidental releases of MOCA into the environment of 10 pounds or more must be reported to EPA.
  • ACGIH: The American Conference of Governmental Industrial Hygienists (ACGIH) set a maximum level of 0.11 milligrams of MBOCA per cubic metre (0.11 mg/m³) of workplace air for an 8-hour workday, 40-hour workweek.
  • NIOSH: The National Institute for Occupational Safety and Health (NIOSH) recommends an exposure limit of 3 micrograms of MOCA per cubic metre of air (3 mg/m³) over a 10-hour day.
  • These agencies advise avoiding eye and skin contact because this may be a route of significant exposure.

Australia [7]

  • Safe Work Australia: Safe Work Australia has established a time weighted average concentration for MOCA of 0.02ppm and 0.22 mg/m3 for an 8-hour workday, 40-hour workweek.