Isocyanates

Objectives:

- To understand the dangers of Isocyanates.
- To avoid personal injury due to misuse of Isocyanates.
- To learn quick tips to protect you and your coworkers from Isocyanates.

Technician Awareness on Isocyanate Safety
Isocyanates are chemicals used in automotive repair that can harm those exposed to them, or even cause the death of a person under the wrong set of circumstances.

Many years ago, when gasoline was first developed to fuel cars, people didn’t understand how to handle it, and fires and explosions were common. Today, no one thinks much about gasoline, because handling it properly has become a way of life.

Just as with gasoline in previous times, Isocyanates are not well understood today.

Dangers exist for all kinds of chemicals, and the risks associated with Isocyanates (also referred to as “Diisocyanates”) must be considered. This long chemical name covers a group of low-molecular-weight aromatic and aliphatic compounds. They are widely used in and around automotive repair and especially in paints and some two part adhesives.

Isocyanates and Paint
Modern automotive paints come in two parts; the first part is the paint, and the second is a hardener. When blended together, the two chemicals cause the paint to “harden” faster and become more durable than a paint that dries from solvent evaporation. As a result, the paint job lasts longer and keeps its gloss – but there is a negative by-product that must be handled properly.

When the two parts are mixed, they form an isocyanate that may be odorless and invisible. Paint-related Isocyanates are in the form of a heavier-than-air gas, and although the quantity of Isocyanates generated is not large, there is enough – over time – to hurt an individual.

How Does Exposure Happen?
A technician can be exposed to Isocyanates through inhalation of the vapor, gas or aerosol.
In other words, breathing Isocyanates can hurt you. And remember, the Isocyanate is separate from the paint or thinners, which can also hurt you if inhaled.

Isocyanate exposure may also occur through skin contact during the handling of liquid Isocyanates. Painters or people using two-part products are at risk if they work without gloves or don’t change clothing on a regular basis.

Case - Spray Painting (Resulted in Death)*
A 37-year-old male, self-employed car painter was admitted to the hospital with asthma symptoms. These symptoms had first started five years earlier and even then were thought to be related to his occupation. Apparently shop conditions were poor and he was not trained and/or decided not to adopt safe working habits or use protective personal equipment. He had been working in the same work environment for more than 20 years.

The man was diagnosed by a doctor with occupational asthma “induced by Isocyanates”. Medical experts advised him to change his job or avoid the use of two part or catalyzed polyurethane paints. In spite of the advice, he continued to work. He used medications such as bronchodilators, cromolyn, and steroids to self medicate and treat his condition.

Six years later, and in spite of doctors’ recommendations, the painter was still working. While spraying a car with an isocyanate paint, he developed a more severe, prolonged asthma condition. Despite medication, he remained symptomatic, especially at night. When he returned to work and sprayed the polyurethane paint yet again, he suffered a severe asthma attack. He died in the ambulance enroute to the hospital.

Health Effects of Isocyanates
Isocyanates are powerful irritants to the eyes and gastrointestinal as well as the respiratory tracts. Direct skin contact with Isocyanates can also cause marked inflammation. Some people say that their eyes feel like they have sand in them at the onset of problems. Some break out in a rash on their arms, chest, and neck.

Becoming Sensitized to Isocyanates
Overexposure to Isocyanates can “sensitize” workers, making them subject to asthma attacks if they are exposed again. Respiratory irritation may progress to a chemical bronchitis. Additional exposures can make the onset easier with less isocyanate necessary to start the attack.

Sporadic cases of hypersensitivity pneumonitis (HP) have also been reported in workers exposed to Isocyanates. The symptoms may seem like the flu, with fever, muscle aches, and headaches. Other symptoms may include a dry cough, chest tightness, and difficult breathing. Individuals with chronic HP often experience progressively more difficult breathing, fatigue, and weight loss. Individuals with acute HP typically develop symptoms 4-6 hours after exposure.

Recommendations
The following recommendations are intended to reduce the potential for exposed workers to develop adverse health effects. Because Isocyanates are also a potential occupational carcinogen, appropriate engineering controls and work practices should be used to reduce worker exposures to the lowest possible concentration.

Product Substitution
When possible, employers should substitute a less hazardous material for Isocyanates. Make sure you read the MSDS sheet on any paint, hardeners, or two part products to check for Isocyanates. The label on the can will help as well.

Paint Booths-Closed Systems and Ventilation
Engineering controls, such as closed systems and ventilation, should be the principal method for minimizing Isocyanate exposure in the workplace. Practically speaking, the best way for painters to avoid Isocyanates is to spray using modern downdraft paint booth technology. Avoid spraying two part paints or anything with a hardener or catalyst in a closed or non-approved area. In other words, don’t spray in the open.

Downdraft booths, when operating properly, bring fresh air over the vehicle being painted and carry the Isocyanate and paint materials downward away from the painter’s face and body.

Paint Mix Rooms and Ventilation
Paint mix rooms should have sufficient ventilation as well. The pickup vent for air to be evacuated should be low in the room, since Isocyanate fumes are heavier than air and flow downward.

Worker Isolation From Isocyanates
Areas containing Isocyanates should be restricted to essential workers. Only use Isocyanates if you have been properly trained on equipment and personal protective clothing and equipment. Never let others come into a paint booth without proper equipment – even to “just take a quick look.” Be careful when mixing paint as you can stir up the Isocyanates toward your face.

Protective Clothing and Equipment
When there is potential for Isocyanate exposure, workers should be provided with and required to use appropriate personal protective clothing and equipment. Keep paint and two-part adhesives off your skin by using coveralls, footwear, chemical-resistant gloves and goggles. When handling two-part paints that could splash on hands, most paint companies recommend using inexpensive disposable nitrile gloves

Respiratory Protection
If you have a good spray booth and a mix room that provides fresh air, your next step of protection is a quality personal respirator. Respirators should not be used as the primary control for Isocyanates.

Only the most protective respirators should be used for situations involving exposures to Isocyanates that have poor warning properties (remember you may not be able to see or smell them), are potent sensitizers, or may be carcinogenic. These respirators include any self-contained breathing apparatus with a full facepiece operated in a pressure-demand or other positive-pressure mode, and any supplied-air respirator with a full facepiece operated in a pressure-demand or other positive-pressure mode in combination with an auxiliary self-contained breathing apparatus operated in a pressure-demand or other positive-pressure mode.

Schools and businesses must have and use a respiratory protection program to meet the requirements of the OSHA respiratory protection standard. A complete respiratory protection program will include:

1) Regular training and medical evaluation of personnel,
2) Fit testing,
3) Periodic environmental monitoring,
4) Periodic maintenance, inspection, and cleaning of respirators and related equipment,
5) Proper storage of equipment, and
6) Written standard operating procedures governing the selection and use of respirators.

The program should be evaluated regularly.

Worker and Employer Education
Worker education is vital to a good occupational safety and health program. OSHA requires that workers be informed about materials that may contain or be contaminated with Isocyanates, and the nature of the potential hazard. Employers must transmit this information through container labeling, material safety data sheets (MSDS), and worker training.

Medical Monitoring
A medical monitoring program should be established for the early detection and prevention of the acute and chronic effects of exposure to Isocyanates. The worker's physician should be given information about the adverse health effects of exposure to Isocyanates and the worker's potential for exposure.

Summary
Isocyanates are a hazard, but educated technicians, students and businesses can handle them properly and safely. It is the responsibility of all of the above to know the rules and the methods to stay safe on the job when working with Isocyanate generating products.

Contacts and Regulatory Links

The National Institute for Occupational Safety and Health (NIOSH) ( http://www.cdc.gov/niosh/ ), The Occupational Safety and Health Association (OSHA)( http://www.osha.gov ), and the U.S. Environmental Protection Agency (EPA)( http://www.epa.gov ) requests assistance in preventing asthma, other respiratory disease, and death from isocyanate exposure. Information about preventing adverse health effects from exposure to isocyanate is urgently needed by workers and employers, small businesses, physicians, and other health care providers.

OSHA ( http://www.osha.gov )
The current OSHA permissible exposure limit (PEL) for TDI is 0.02 part per million parts of air, or 0.14 milligram per cubic meter of air as a ceiling limit. When updating its air contaminants standard in 1989, OSHA decreased this limit to 0.005 ppm as an 8-hour time-weighted average (TWA) and 0.02 ppm as a short-term exposure limit; however, this standard was rescinded by court order in 1992. The OSHA PEL for MDI is 0.02 ppm as a ceiling limit.

NIOSH ( http://www.cdc.gov/niosh/ )
In two separate criteria documents, NIOSH has recommended that TDI exposure be limited to 0.005 ppm as a TWA for up to a 10-hour workday during a 40-hour workweek, with a ceiling concentration of 0.02 ppm for any 10-minute period.

This NIOSH-recommended exposure limit (REL) was intended to prevent acute and chronic irritation and sensitization of workers but not to prevent responses in workers who are already sensitized.

ACGIH ( http://www.acgih.org/ )
The American Conference of Governmental Industrial Hygienists (ACGIH) threshold limit value (TLV) for TDI is 0.005 ppm as an 8-hour TWA and 0.02 ppm as a short-term exposure limit. The ACGIH TLV for MDI is 0.005 ppm as a TWA.

S/P2 urges you to share this article with all workers at risk. Your assistance will help prevent asthma and other respiratory disease in the 280,000 U.S. workers potentially exposed to Isocyanates.