Skip directly to site content Skip directly to page options Skip directly to A-Z link


Centers for Disease Control and Prevention. CDC twenty four seven. Saving Lives, Protecting People
															Search
		×
			NIOSH
			NIOSH
				All CDC
				Submit
			For a full list of topics:A-Z Index
			Advanced Search
		Advanced Search


The National Institute for Occupational Safety and Health (NIOSH)


Facebook
        Twitter
        LinkedIn
        Syndicate





Current Intelligence Bulletin 21: Trimellitic Anhydride (TMA)										Related Pages
										February 3, 1978
DHHS (NIOSH) Publication Number 78-121

Synonyms
Anhydrotrimellitic Acid
1,2,4-Benzenetricarboxylic Acid Anhydride
1,2,4-Benzenetricarboxylic Acid, Cyclic 1,2-Anhydride
1,2,4-Benzenetricarboxylic Anhydride
4-Carboxyphthalic Anhydride
Chemical Abstracts Service Number: 552-30-7
Chemical Formula: C9H4O5
1,3-Dihydro-1,3-Dioxo-5-Isobenzofurancarboxylic Acid
1,3-Dioxo-5-Phthalancarboxylic Acid
Diphenylmethane-4,4′-Diisocyanate-Trimellic
Anhydride-Ethomid HT Polymer
NIOSH – RTECS DC20500 TMA*
TMAN
Trimellitic Acid Anhydride
Trimellitic Acid 1,2-Anhydride
Trimellitic Acid Cyclic 1,2-Anhydride
*TMA is also an acronym for trimethylamine. [return to text]
Trimellitic Anhydride (TMA)
The National Institute for Occupational Safety and Health (NIOSH) recommends that trimellitic anhydride (TMA) be handled as an extremely toxic agent in the workplace. Exposure to this compound may result in noncardiac pulmonary edema (apparently without benefit of a pulmonary irritation warning), immunological sensitization, and irritation of the pulmonary tract, eyes, nose, and skin. There is no current Occupational Safety and Health Administration (OSHA) exposure standard for trimellitic anhydride.
The Amoco Chemicals Corporation, the sole domestic producer, suggests a limit of “0.05 mg/m3 or less for susceptible individuals.”1
NIOSH has prepared this Current Intelligence Bulletin to advise you of recent findings of toxic effects of trimellitic anhydride and to provide some precautions for handling trimellitic anhydride in the workplace. Attached are “Suggested Procedures for Minimizing Employees’ Exposure to Trimellitic Anhydride.”

Potential Occupational Exposures
NIOSH estimates approximately 20,000 American workers are currently at risk of exposure to trimellitic anhydride in its various applications. TMA is used as a curing agent for epoxy and other resins, in vinyl plasticizers, paints and coatings, polymers, polyesters, agricultural chemicals, dyes and pigments, pharmaceuticals, surface active agents, modifiers, intermediates, and specialty chemicals. The sole domestic producer of trimellitic anhydride is Amoco Chemicals Corporation which has a 50 million pound-per-year plant at Joliet, Illinois.

Human Toxicity
The ability for trimellitic anhydride to cause pulmonary edema (excessive fluid in the lungs) has been demonstrated by Rice *et al*.2 workers had been employed by the same company for only a short period of time (3 and 6 weeks). They received multiple inhalation exposures to an epoxy resin containing trimellitic anhydride when it was sprayed on heated pipes. The levels of trimellitic anhydride were not available to the authors. No mention was made of severe irritation of the upper respiratory tract while they were receiving their exposures, suggesting little or no warning of subsequent damage to the lungs. The possibility that the pulmonary edema was the result of a hypersensitivity reaction must therefore be considered. Resins can be sensitizers (e.g., toluene diisocyanate or TDI), though most of the reported effects have been those of direct irritation.3
Sensitization to trimellitic anhydride was reported by Zeiss *et al.*4 Respiratory symptoms were observed in fourteen workers employed in the synthesis of trimellitic anhydride. The authors suggest three distinct syndromes induced by inhalation of TMA.
The first, rhinitis and/or asthma, developed over an industrial exposure period of weeks to years. After this period, the sensitized worker exhibited symptoms immediately following exposure to trimellitic anhydride dust or fume, which abated after the work exposure had stopped. The second syndrome, termed “TMA-flu” by the workers, also required a sensitization period of exposure and was characterized by delayed onset cough, wheezing, and labored breathing starting 4 to 8 hours after a work shift and peaking at night. These respiratory symptoms were usually accompanied by malaise, chills, fever, muscle and joint aches, and appeared to be associated with relatively high exposures to trimellitic anhydride during particular work shifts. The third syndrome, which followed initial high exposure to TMA, was primarily an irritant effect. It was characterized by a “running” nose without itching or sneezing, occasional nosebleed, cough, labored breathing, and occasional wheezing. Symptoms usually abated after 8 hours and rarely lasted into the night.
The above studies suggest harmful respiratory effects of trimellitic anhydride at relatively high concentrations, but even at lower concentrations some workers may develop an immunological sensitization over a period of time.
Fawcett *et al.*5 also observed sensitization in a worker exposed to trimellitic anhydride in the production of tubular steel shop fittings coated with an epoxy resin. The chemical agent responsible for asthma symptoms of six workers was identified by careful inhalation challenge testing, simulating work exposure. Typical attacks which began one year after onset of TMA exposure consisted of cough and breathlessness lasting for 30 minutes, which subsided, only to be followed the same evening by sneezing which persisted for about 24 hours. Subsequent attacks were prevented by avoiding exposure.
Data on occupational exposures to trimellitic anhydride were also obtained during a NIOSH Health Hazard Evaluation of a paint and varnish company during the manufacture of an epoxy paint.6 The Health Hazard Evaluation was conducted at the request of employees who were concerned about possible harmful effects of trimellitic anhydride exposure during processing and decontamination operations. The occupational airborne exposure levels averaged 1.5 mg/m3 TMA (with a range from “none detected” to 4.0 mg/m3) during processing operations and 2,8 mg/m3 TMA (ranging from “none detected” to 7,5 mg/m3) during decontamination operations. A total of 13 employees (5 present and 8 former employees) were interviewed and briefly examined. Employees’ symptoms and complaints were: eye irritation, nasal irritation, shortness of breath, wheezing, cough, heartburn, nausea, headache, skin irritation, and throat irritation. Three of the former workers stated that they had left that department for health reasons. Complaints subsided when non-TMA-containing products were being formulated.
The Occupational Health and Safety Division, Department of Labour, Alberta, Canada, has reported to NIOSH that they are aware of employee reactions in two plants using TMA-epoxy powder pipe coatings. The one plant, started in 1971, had a number of employees with an immediate reaction. After instituting engineering and administrative controls, there has been no further incidence. In the second plant, began in 1974, the first adverse reaction occurred in 1975. There have been 9 cases of adverse reactions reported to date. Most of these employees were kept in intensive care while they recuperated and were advised by their physicians to seek new jobs. However, some returned to their previous jobs and became ill again. Due to the unavailability of a good analytical method for trimellitic anhydride occupational levels could not be documented until November of 1977. The TMA concentrations found ranged from 0.11 mg/m3 to 0.27 mg/m3.
In view of the employer’s responsibility, “to furnish to each of his employees employment and a place of employment which are free from recognized hazards that are causing or likely to cause death or serious physical harm to his employees...,” occupational exposure to trimellitic anhydride should be minimized. It appears evident that trimellitic anhydride, a known irritant, can cause severe pulmonary edema, immunological sensitization, and asthma symptoms.
*[signature]*
J. Donald Millar, M.D.
Assistant Surgeon General
Acting Director
Suggested Minimizing Employee Trimellitic Anhydride (TMA)

Control of Overexposures
NIOSH recommends that trimellitic anhydride be handled in the workplace as an extremely toxic substance because it can cause noncardiac pulmonary edema, immunological sensitization, and severe respiratory irritation. Exposure to trimellitic anhydride should be limited to as few employees as possible, while minimizing workplace exposure levels. The area in which it is used should be restricted to those employees necessary to the process or operation. Furthermore, consideration should be given to isolating the trimellitic anhydride exposure area so that adjacent workers are not also exposed.
**Exposure Monitoring**
The NIOSH Occupational Exposure Sampling Strategy Manual, NIOSH Publication #77-173, may be helpful in developing efficient programs to monitor employee exposures to trimellitic anhydride. The manual discusses determination of the need for exposure measurements, selection of appropriate employees for sampling, and selection of sampling times.
Exposure measurements should consist of 8-hour TWA (time-weighted average) exposure estimates calculated from personal or breathing zone samples (air that would most nearly represent that inhaled by the employees).
**Engineering Controls**
Engineering and work practice controls should be used to minimize employee exposure to trimellitic anhydride.
To ensure that ventilation equipment is working properly, effectiveness (e.g., air velocity, static pressure or air volume) should be checked at least every three months.
System effectiveness should also be checked within five days of any change in production, process, or control which might result in significant increases in airborne exposures to trimellitic anhydride.
**Respiratory Protection**Exposure to trimellitic anhydride should not be controlled with the use of respirators except:
During the time period necessary to install or implement engineering or work practice controls; or
In work situations in which engineering and work practice controls are technically not feasible; or
To supplement engineering and work practice controls when such controls fail to adequately control exposure to trimellitic anhydride; or
For operations which require entry into tanks or closed vessels; or
In emergencies.
Respirators should be approved by the National Institute for Occupational Safety and Health (NIOSH) or by the Mining Enforcement and Safety Administration (MESA). Refer to *NIOSH Certified Equipment, December 15, 1975,* NIOSH publication #76-145 and *Cumulative Supplement June 1977, NIOSH Certified Equipment,* NIOSH publication #77-195. The use of faceseal coverlets or socks with any respirator voids NIOSH/MESA approvals.
Quantitative faceseal fit test equipment (such as sodium chloride, dioctyl phthalate, or equivalent) should be used. Refer to *A Guide to Industrial Respiratory Protection,* NIOSH publication #76-189 for guidelines on appropriate respiratory protection programs.
Where respirators are needed and NIOSH recommendations allow their use to reduce employee exposure, the following types of respirators may be used. They are listed in order of increasing protection factors.
**Protection factor of 50:** chemical cartridge respirator with a full facepiece, organic vapor cartridges, and high efficiency filter(s) (30 CFR 11.150 and 11.130); any gas mask with a chin-style organic vapor canister and high efficiency filter (30 CFR 11.90(a) and 11.130); any supplied-air respirator with a full facepiece, helmet, or hood (30 CFR 11.110(a)); any self-contained breathing apparatus with a full facepiece (30 CFR 11.70(a)).
**Protection factor of 1000:** powered air purifying chemical cartridge respirator with full facepiece, organic vapor cartridges, and high efficiency particulate filter(s).
**Protection factor of 2000:** type C supplied-air respirator with a full facepiece operated in positive pressure-demand or other positive pressure mode or with a full facepiece, hood, or helmet operated in continuous flow mode (30 CFR 11.110(a)).
**Protection factor of 10,000+:** -contained breathing apparatus with a full facepiece operated in positive pressure-demand or other positive pressure mode (30 CFR 11.70(a)); any combination respirator which includes a type C supplied-air respirator with a full facepiece operated in positive pressure-demand or other positive pressure or continuous flow mode and an auxilary self-contained breathing apparatus operated in positive pressure-demand or positive pressure mode (30 CFR 11.7O(b)).
Personal Protective Equipment
Employers should provide appropriate protective clothing and equipment necessary to prevent repeated or prolonged skin contact with trimellitic anhydride.
Employers should see that employees whose clothing may have become contaminated with trimellitic anhydride change into uncontaminated clothing before leaving the work premises.
Employers should see that non-impervious clothing which becomes contaminated with trimellitic anhydride be promptly removed and not reworn until the trimellitic anhydride is removed from the clothing.
Employers should see that clothing contaminated with trimellitic anhydride is placed in closed containers for storage until it can be discarded or removed from the clothing. If the clothing is to be laundered or otherwise cleaned to remove the trimellitic anhydride, the employer should tell the person performing the cleaning operation of the hazardous properties of trimellitic anhydride.
Employers should provide dust-resistant safety goggles where there is any possibility of trimellitic anhydride dust contacting the eyes.

References
Amoco-Industrial Hygiene Toxicology and Safety Data Sheet, Environmental Health Services, Medical and Health Services Department, July 8, 1976.
Rice, D. L., Jenkins, D. E., Gray, J. M., and Greenberg, S. D., “Chemical Pneumonitis Secondary to Inhalation of Epoxy Pipe Coating,” Archives of Environmental Health 32(4): 173-8, July-August 1977.
Patty, F. A., ed, Industrial Hygiene and Toxicology, Second Revised Edition, Volume II, Fawcett, D. W., Irish, D, D., eds. John Wiley & Sons, Inc., New York.
Zeiss, C. R., Patterson, R., Pruzansky, J.J., Miller, M. M., Rosenberg, M., Levitz, D., “Trimellitic Anhydride-Induced Airway Syndromes: Chemical and Immunologic Studies”, J. Allergy & Clinical Immunology 60(2): 96-103, August 1977.
Fawcett, D. W., Taylor, A. J., Pepys, J. “Asthma Due to Inhaled Chemical Agents-Epoxy Resin Systems Containing Phthalic Acid Anhydride, Trimellitic Acid Anhydride and Triethylene Tetramine”, Clinical Allergy 7(l): -14, January 1977.
National Institute for Occupational Safety and Health, Health Hazard Evaluation Determination Report No. 74-111-283.
							
					
						Page last reviewed:  June 6, 2014					Content source: 	National Institute for Occupational Safety and Health homeNIOSH Publications & Products
NIOSH-Issued Publications
Search NIOSHTIC-2 Research Database
Docket
Documents for Public Review
Peer Review Agenda
Databases
eNews
Federal Register Noticesplus icon
FRN Archive 2007-2010
FRN Archive 2005-2006
FRN Archive 2001-2004
FRN Archive 1996-2000
Press Releases and Updatesplus icon
Press Release Archives 2010-2013
Press Release Archives 2006-2009
Press Release Archives 2001-2005
Press Release Archives 1998-2000
Press Release Archives 1992-1997
Regulations
Regulatory Agenda
Science Blog
Software
Video Follow NIOSH Facebook
Pinterest
Twitter
YouTube
 NIOSH Homepage NIOSH A-Z
Workplace Safety & Health Topics
Publications and Products
Programs
Contact NIOSH


About CDC
					Contact Us
					800-232-4636
 Facebook Twitter Instagram LinkedIn Youtube Pinterest Snapchat
 CONTACT CDC
				Contact Us
							Call 800-232-4636
							Email Us
			ABOUT CDC
				About CDC
							Jobs
							Funding
			POLICIES
				Accessibility
							External Links
							Privacy
							Policies
							No Fear Act
							FOIA
							OIG
							Nondiscrimination
							Vulnerability Disclosure Policy
			CONNECT WITH US
				Facebook
								Twitter
								Instagram
								LinkedIn
							Youtube
								Pinterest
								Snapchat
								Email
			LANGUAGES
				Español
							繁體中文
							Tiếng Việt
							한국어
							Tagalog
							Русский
							العربية
							Kreyòl Ayisyen
							Français
							Polski
							Português
							Italiano
							Deutsch
							日本語
							فارسی
							English


U.S. Department of Health & Human Services
			Accessibility
			External Links
			Privacy
			Policies
			No Fear Act
			FOIA
			Nondiscrimination
			OIG
			Vulnerability Disclosure Policy
			USA.gov


Exit Notification / Disclaimer Policy Close
 Links with this icon  indicate that you are leaving the CDC website. The Centers for Disease Control and Prevention (CDC) cannot attest to the accuracy of a non-federal website.
				Linking to a non-federal website does not constitute an endorsement by CDC or any of its employees of the sponsors or the information and products presented on the website.
				You will be subject to the destination website's privacy policy when you follow the link.
				CDC is not responsible for Section 508 compliance (accessibility) on other federal or private website. Website Disclaimers
 Cancel Continue