Disclaimer: These guidelines were developed under contract using generally accepted secondary sources. The protocol used by the contractor for surveying these data sources was developed by the National Institute for Occupational Safety and Health (NIOSH), the Occupational Safety and Health Administration (OSHA), and the Department of Energy (DOE). The information contained in these guidelines is intended for reference purposes only. None of the agencies have conducted a comprehensive check of the information and data contained in these sources. It provides a summary of information about chemicals that workers may be exposed to in their workplaces. The secondary sources used for supplements 111 and 1V were published before 1992 and 1993, respectively, and for the remainder of the guidelines the secondary sources used were published before September 1996. This information may be superseded by new developments in the field of industrial hygiene. Therefore readers are advised to determine whether new information is available.

OCCUPATIONAL SAFETY AND HEALTH GUIDELINE FOR DIMETHYLAMINE

INTRODUCTION

This guideline summarizes pertinent information about dimethylamine for workers and employers as well as for physicians, industrial hygienists, and other occupational safety and health professionals who may need such information to conduct effective occupational safety and health programs. Recommendations may be superseded by new developments in these fields; readers are therefore advised to regard these recommendations as general guidelines and to determine whether new information is available.

SUBSTANCE IDENTIFICATION

* Formula

C(2)()H(7)N

* Structure

Data not available.

* Synonyms

Anhydrous dimethylamine, dimethylamine (aqueous solution), DMA, N-methylmethanamine

* Identifiers

1. CAS No.: 124-40-3

2. RTECS No.: IP8750000

3. DOT UN: 1032 19 (Anhydrous); 1160 26 (Solution)

4. DOT label: Flammable gas (Anhydrous); Flammable liquid (Solution)

* Appearance and odor

Dimethylamine is a colorless, flammable gas with a pungent, fishy, or ammonia-like odor at room temperature; it is shipped and marketed in compressed liquid form. The air odor threshold concentration for dimethylamine is 0.34 part per million (ppm) parts of air.

CHEMICAL AND PHYSICAL PROPERTIES

* Physical data

1. Molecular weight: 45.1

2. Boiling point (at 760 mm Hg): 7 degrees C (45 degrees F)

3. Specific gravity (water = 1): 0.68 (liquid) at 20 degrees C (68 degrees F)

4. Vapor density: 1.6

5. Freezing point: -92 degrees C (-134 degrees F)

6. Vapor pressure at 20 degrees C (68 degrees F): 1292 mm Hg

7. Solubility: Very soluble in water; soluble in alcohol and ether.

8. Evaporation rate: Data not available.

* Reactivity

1. Conditions contributing to instability: Heat or flame.

2. Incompatibilities: Contact between dimethylamine and oxidizing materials, acrylaldehyde, fluorine, maleic anhydride, chlorine, or mercury should be avoided. Vapors form explosive mixtures with air.

3. Hazardous decomposition products: Toxic gases and vapors (such as oxides in nitrogen and carbon monoxide) may be released in a fire involving dimethylamine.

4. Special precautions: Liquid dimethylamine will attack some forms of plastic, rubber, and coatings.

* Flammability

The National Fire Protection Association has assigned a flammability rating of 4 (extreme fire hazard) to dimethylamine.

1. Flash point: None (gas); 12.2 degrees C (54 degrees F) (liquid)

2. Autoignition temperature: 402 degrees C (755 degrees F)

3. Flammable limits in air (percent by volume): Lower, 2.8; upper, 14.4

4. Extinguishant: For small fires use dry chemical or carbon dioxide. Use water spray, fog, or regular foam to fight large fires involving dimethylamine.

Fires involving dimethylamine should be fought upwind from the maximum distance possible. Dimethylamine is extremely flammable and may be ignited by heat, sparks, or open flames. Keep unnecessary people away; isolate the hazard area and deny entry. Isolate the area for 1/2 mile in all directions if a tank, rail car, or tank truck is involved in the fire. For a massive fire in a cargo area, use unmanned hose holders or monitor nozzles; if this is impossible, withdraw from the area and let the fire burn. Emergency personnel should stay out of low areas and ventilate closed spaces before entering. Vapors may travel to a source of ignition and flash back. Vapors are an explosion and poison hazard indoors, outdoors, or in sewers. Containers of dimethylamine may explode in the heat of the fire and should be moved from the fire area if it is possible to do so safely. If this is not possible, cool fire exposed containers from the sides with water until well after the fire is out. Stay away from the ends of containers. Personnel should withdraw immediately if a rising sound from a venting safety device is heard or if there is discoloration of a container due to fire. Firefighters should wear a full set of protective clothing and self-contained breathing apparatus when fighting fires involving dimethylamine.

EXPOSURE LIMITS

* OSHA PEL The current Occupational Safety and Health Administration (OSHA) permissible exposure limit (PEL) for dimethylamine is 10 ppm (18 milligrams per cubic meter (mg/m(3))) as an 8-hour time-weighted average (TWA) concentration [29 CFR 1910.1000, Table Z-1].

* NIOSH REL

The National Institute for Occupational Safety and Health (NIOSH) has established a recommended exposure limit (REL) for dimethylamine of 10 ppm (18 mg/m(3)) as a TWA for up to a 10-hour workday and a 40-hour workweek [NIOSH 1992].

* ACGIH TLV

The American Conference of Governmental Industrial Hygienists (ACGIH) has assigned dimethylamine a threshold limit value (TLV) of 5 ppm (9.2 mg/m(3)) as a TWA for a normal 8-hour workday and a 40-hour workweek and a short-term exposure limit (STEL) of 15 ppm (27.6 mg/m(3)) for periods not to exceed 15 minutes. Exposures at the STEL concentration should not be repeated more than four times a day and should be separated by intervals of at least 60 minutes [ACGIH 1994, p. 19].

* Rationale for Limits

The NIOSH limit is based on the risk of respiratory, eye, and mucous membrane irritation (effects reported in animals) [NIOSH 1992]. The ACGIH limits are based on analogy to the toxicity of methylamine and ethylamine, and on the effects noted in animal inhalation studies [ACGIH 1991, p. 480].

HEALTH HAZARD INFORMATION

* Routes of Exposure

Exposure to dimethylamine can occur through inhalation, ingestion, and eye or skin contact [Sittig 1991].

* Summary of toxicology

1. Effects on Animals: Dimethylamine is an irritant of the eyes, skin, mucous membranes, and respiratory tract [Hathaway et al. 1991]. The 6-hour LC(50) in rats is 4,540 ppm. The oral LD(50) in mice, rats, and guinea pigs are 316 mg/kg, 698 mg/kg, and 240 mg/kg, respectively. A post-mortem examination revealed severe irritation of the gastric mucosa, accompanied by hemorrhage in the stomach wall [ACGIH 1991]. Eye irritation, gasping, tearing, salivation, and bloody discharge from the nose were noted in rats after 1 hour of exposure at 4540 ppm. Corneal opacity occurred 3 hours after the exposure began, and death was usually preceded by convulsions. At autopsy, severe congestion, ulceration, and necrosis of the nasal turbinates were observed [Hathaway et al. 1991]. In rats exposed for 6 hours to sublethal concentrations ranging from 600 ppm to 2,500 ppm, eye irritation, gasping, and bloody discharge from the nose were noted. At concentrations greater than 2500 ppm, emphysema, bronchopneumonia, liver cell death, and corneal ulceration occurred. Exposures to concentrations of 170 to 500 ppm resulted in less severe lung changes. Animals of several species were exposed to approximately 100 to 200 pm of dimethylamine for 18 to 20 weeks and developed marked irritation of the respiratory tract and pulmonary edema and also sustained injury to the liver. Among the guinea pigs and rabbits exposed on this regiment, corneal injury was observed after 9 days of exposure; degenerative changes of the testicles occurred in one monkey and one of ten rats in these experiments. Continuous exposure to 5 ppm dimethylamine for 90 days resulted in no overt signs of toxicity, but autopsy showed inflammatory changes in the lungs. Long-term oral exposure to 0.035 mg/kg caused no apparent effect in rats and guinea pigs [Hathaway et al. 1991; ACGIH 1991; NLM 1995]. Skin contact with dimethylamine results in necrosis, and eye contact causes severe corneal injury or permanent corneal opacity [Hathaway et al. 1991; Grant 1986].

2. Effects on Humans: Dimethylamine is an irritant of the eyes, skin, mucous membranes, and respiratory tract [ACGIH 1991; NLM 1995]. A splash of dimethylamine into the eyes causes intense pain, severe damage, and permanent corneal opacities. Coughing, sneezing, an shortness of breath can occur after inhalation of dimethylamine. Skin contact with the liquid may cause minor irritation on short contact and prolonged contact may result in necrosis of the skin [Genium 1986]. By analogy with the effects observed in experimental animals, sublethal doses could result in delayed tracheitis, bronchitis, pulmonary edema, and pneumonitis, and ingestion could lead to gastric irritation and hemorrhage. Long-term inhalation has caused liver damage in animals [ACGIH 1991]. Dermatitis and conjunctivitis have occasionally been observed in workers after prolonged exposure to dimethylamine gas [Genium 1986; NLM 1995].

* Signs and symptoms of exposure

1. Acute exposure: The gas is irritating to the eyes and can cause redness and pain of the conjunctiva. In liquid form, contact with the eye causes severe pain and corneal injury. Redness and burning of the skin are caused by mild exposure to the liquid, but prolonged exposure causes lesions that are similar to second-degree burns. Severe inhalation exposure cause runny nose, coughing, sneezing, and burning of the nose and throat, and shortness of breath. Delayed pulmonary effects may occur in the form of tracheitis, bronchitis, pulmonary edema, and pneumonitis, which may be associated with persistent cough, increased bronchial secretions, and shortness of breath at rest, fever, and respiratory distress [Hathaway et al. 1991].

2. Chronic exposure: Dermatitis and conjunctivitis have been reported to occur after prolonged exposure to dimethylamine gas [NLM 1995].

EMERGENCY MEDICAL PROCEDURES

* Emergency medical procedures: [NIOSH to supply]

5. Rescue: Remove an incapacitated worker from further exposure and implement appropriate emergency procedures (e.g., those listed on the Material Safety Data Sheet required by OSHA's Hazard Communication Standard [29 CFR 1910.1200]). All workers should be familiar with emergency procedures, the location and proper use of emergency equipment, and methods of protecting themselves during rescue operations.

EXPOSURE SOURCES AND CONTROL METHODS

The following operations may involve dimethylamine and lead to worker exposures to this substance:

* The manufacture and transportation of dimethylamine

* Chemical intermediate for dimethylformamide and dimethylacetamide (both solvents for acrylic fibers), lauryl dimethylamine oxide (a surfactant), dimethylamine salt of 2,4-D, and unsymmetrical dimethylhydrazine

* Used as raw material in synthesis of agricultural insecticides, insect attractants, and fungicides; vulcanization accelerators for sulfur-cured rubber; softeners and lubricants; textile water-proofing agents; tanning and dehairing; cationic surfactants; pharmaceuticals; detergents and soaps

* Used as a general solvent, an acid gas absorbent and flotation agent in manufacture of dyes and in electroplating, and as an antioxidant

* Used as a stabilizer for certain types of resins (polymerization inhibitor), in natural rubber latex and in gasoline

* Used as a component of missile fuel and rocket and pesticide propellants; as an anti-knock agent in other fuels; as a retarder in spinning bath of rayon (for tire cord)

* Used as a corrosion inhibitor in iron, steel, and metal industries and used as a reagent for magnesium.

Methods that are effective in controlling worker exposures to dimethylamine, depending on the feasibility of implementation, are as follows:

* Process enclosure
* Local exhaust ventilation
* General dilution ventilation
* Personal protective equipment

Workers responding to a release or potential release of a hazardous substance must be protected as required by paragraph (q) of OSHA's Hazardous Waste Operations and Emergency Response Standard [29 CFR 1910.120].

Good sources of information about control methods are as follows:

1. ACGIH [1992]. Industrial ventilation--a manual of recommended practice. 21st ed. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.

2. Burton DJ [1986]. Industrial ventilation--a self study companion. Cincinnati, OH: American Conference of Governmental Industrial Hygienists.

3. Alden JL, Kane JM [1982]. Design of industrial ventilation systems. New York, NY: Industrial Press, Inc.

4. Wadden RA, Scheff PA [1987]. Engineering design for control of workplace hazards. New York, NY: McGraw-Hill.

5. Plog BA [1988]. Fundamentals of industrial hygiene. Chicago, IL: National Safety Council.

MEDICAL SURVEILLANCE

OSHA is currently developing requirements for medical surveillance. When these requirements are promulgated, readers should refer to them for additional information and to determine whether employers whose employees are exposed to dimethylamine are required to implement medical surveillance procedures.

* Medical Screening

Workers who may be exposed to chemical hazards should be monitored in a systematic program of medical surveillance that is intended to prevent occupational injury and disease. The program should include education of employers and workers about work-related hazards, early detection of adverse health effects, and referral of workers for diagnosis and treatment. The occurrence of disease or other work-related adverse health effects should prompt immediate evaluation of primary preventive measures (e.g., industrial hygiene monitoring, engineering controls, and personal protective equipment). A medical surveillance program is intended to supplement, not replace, such measures. To detect and control work-related health effects, medical evaluations should be performed (1) before job placement, (2) periodically during the term of employment, and (3) at the time of job transfer or termination.

* Preplacement medical evaluation

Before a worker is placed in a job with a potential for exposure to dimethylamine, a licensed health care professional should evaluate and document the worker's baseline health status with thorough medical, environmental, and occupational histories, a physical examination, and physiologic and laboratory tests appropriate for the anticipated occupational risks. These should concentrate on the function and integrity of the eyes, skin, respiratory system, and liver. Medical surveillance for respiratory disease should be conducted using the principles and methods recommended by the American Thoracic Society.

A preplacement medical evaluation is recommended to assess medical conditions that may be aggravated or may result in increased risk when a worker is exposed to dimethylamine at or below the prescribed exposure limit. The health care professional should consider the probable frequency, intensity, and duration of exposure as well as the nature and degree of any applicable medical condition. Such conditions (which should not be regarded as absolute contraindications to job placement) include a history and other findings consistent with diseases of the eyes, skin, respiratory system, or liver.

* Periodic medical evaluations

Occupational health interviews and physical examinations should be performed at regular intervals during the employment period, as mandated by any applicable Federal, State, or local standard. Where no standard exists and the hazard is minimal, evaluations should be conducted every 3 to 5 years or as frequently as recommended by an experienced occupational health physician. Additional examinations may be necessary if a worker develops symptoms attributable to dimethylamine exposure. The interviews, examinations, and medical screening tests should focus on identifying the adverse effects of dimethylamine on the eyes, skin, respiratory system, or liver. Current health status should be compared with the baseline health status of the individual worker or with expected values for a suitable reference population.

* Termination medical evaluations

The medical, environmental, and occupational history interviews, the physical examination, and selected physiologic or laboratory tests that were conducted at the time of placement should be repeated at the time of job transfer or termination to determine the worker's medical status at the end of his or her employment. Any changes in the worker's health status should be compared with those expected for a suitable reference population.

* Biological monitoring

Biological monitoring involves sampling and analyzing body tissues or fluids to provide an index of exposure to a toxic substance or metabolite. Dimethylamine can be detected in the blood and urine of exposed workers. However, dimethylamine levels in these fluids cannot be correlated with airborne dimethylamine concentrations. Therefore, no biological monitoring test acceptable for routine use has yet been developed for dimethylamine.

WORKPLACE MONITORING AND MEASUREMENT

Determination of a worker's exposure to airborne dimethylamine is made using a coated XAD-7 tube (80/40 mg sections, 20/50 mesh); coating is 10 percent (w/w) NBD-chloride. Samples are collected at a maximum flow rate of 0.2 liter/minute until a maximum collection volume of 10 liters is reached. The sample is then treated with tetrahydrofuran. Analysis is conducted by high-performance liquid chromatography; HPLC/FLU/VIS. This method (OSHA 34) is fully validated and is described in the OSHA Computerized Information System [OSHA 1994]. NIOSH has published another method (NIOSH Method No. 2010) that can be used to determine a worker's exposure to dimethylamine. This method requires sample collection on a silica gel tube, and sample analysis is performed by gas chromatography using a flame ionization detector (GC/FID) [NIOSH 1994b].

PERSONAL HYGIENE PROCEDURES

If dimethylamine contacts the skin, workers should immediately wash the affected areas twice with soap and water.

Clothing contaminated with dimethylamine should be removed immediately, and provisions should be made for the safe removal of the chemical from the clothing. Persons laundering the clothes should be informed of the hazardous properties of dimethylamine, particularly its potential to be an irritant of the eyes, mucous membranes, respiratory tract, and skin.

A worker who handles dimethylamine should thoroughly wash hands, forearms, and face with soap and water before eating, using tobacco products, using toilet facilities, applying cosmetics, or taking medication.

Workers should not eat, drink, use tobacco products, apply cosmetics, or take medication in areas where dimethylamine or a solution containing dimethylamine is handled, processed, or stored.

STORAGE

Dimethylamine should be stored in a cool, dry, well-ventilated area in tightly sealed containers that are labeled in accordance with OSHA's Hazard Communication Standard [29 CFR 1910.1200]. Containers of dimethylamine should be protected from physical damage and ignition sources, and should be stored separately from oxidizing materials, acrylaldehyde, fluorine, maleic anhydride, chlorine, or mercury. Outside or detached storage is preferred. If stored inside, a standard flammable liquids cabinet or room should be used. Ground and bond metal containers and equipment when transferring liquids. Empty containers of dimethylamine should be handled appropriately.

SPILLS AND LEAKS

In the event of a spill or leak involving dimethylamine, persons not wearing protective equipment and clothing should be restricted from contaminated areas until cleanup has been completed. The following steps should be undertaken following a spill or leak:

1. Notify safety personnel.

2. Remove all sources of heat and ignition.

3. Ventilate potentially explosive atmospheres.

4. Stop leak if this can be done without risk. Use non-sparking tools.

5. Water spray may be used to reduce vapors, but the spray may not prevent ignition in closed spaces; isolate the area until the gas has dispersed.

6. If in liquid form, allow to vaporize. Keep the dimethylamine out of a confined space, such as sewer, because of the possibility of an explosion.

7. Cover small spills involving aqueous solutions with sodium bisulfite. Place waste liquid or absorbent into closed containers.

8. If source of leak is a cylinder and the leak cannot be stopped in place, remove the leaking cylinder to a safe place in the open air, and repair leak or allow cylinder to empty.

9. For large liquid spills, build dikes far ahead of the spill to contain the dimethylamine for later reclamation or disposal.

SPECIAL REQUIREMENTS

U.S. Environmental Protection Agency (EPA) requirements for emergency planning, reportable quantities of hazardous releases, community right-to-know, and hazardous waste management may change over time. Users are therefore advised to determine periodically whether new information is available.

* Emergency planning requirements

Dimethylamine is not subject to EPA emergency planning requirements under the Superfund Amendments and Reauthorization Act (SARA) (Title III) in 42 USC 11022.

* Reportable quantity requirements for hazardous releases

A hazardous substance release is defined by EPA as any spilling, leaking, pumping, pouring, emitting, emptying, discharging, injecting, escaping, leaching, dumping, or disposing into the environment (including the abandonment or discarding of contaminated containers) of hazardous substances. In the event of a release that is above the reportable quantity for that chemical, employers are required to notify the proper Federal, State, and local authorities [40 CFR 355.40].

The reportable quantity of dimethylamine is 1,000 pounds. If an amount equal to or greater than this quantity is released within a 24-hour period in a manner that will expose persons outside the facility, employers are required to do the following:

- Notify the National Response Center immediately at (800) 424-8802 or at (202) 426-2675 in Washington, D.C. [40 CFR 302.6].

* Community right-to-know requirements

Employers are not required by EPA in 40 CFR Part 372.30 to submit a Toxic Chemical Release Inventory form (Form R) to EPA reporting the amount of dimethylamine emitted or released from their facility annually.

* Hazardous waste management requirements

EPA considers a waste to be hazardous if it exhibits any of the following characteristics: ignitability, corrosivity, reactivity, or toxicity as defined in 40 CFR 261.21-261.24. Under the Resource Conservation and Recovery Act (RCRA) [40 USC 6901 et seq.], EPA has specifically listed many chemical wastes as hazardous. Dimethylamine is listed as a hazardous waste under RCRA and has been assigned EPA Hazardous Waste No. U092. This substance has been banned from land disposal until treated by incineration.

Providing detailed information about the removal and disposal of specific chemicals is beyond the scope of this guideline. The U.S. Department of Transportation, EPA, and State and local regulations should be followed to ensure that removal, transport, and disposal of this substance are conducted in accordance with existing regulations. To be certain that chemical waste disposal meets EPA regulatory requirements, employers should address any questions to the RCRA hotline at (703) 412-9810 (in the Washington, D.C. area) or toll-free at (800) 424-9346 (outside Washington, D.C.). In addition, relevant State and local authorities should be contacted for information on any requirements they may have for the waste removal and disposal of this substance.

RESPIRATORY PROTECTION

* Conditions for respirator use

Good industrial hygiene practice requires that engineering controls be used where feasible to reduce workplace concentrations of hazardous materials to the prescribed exposure limit. However, some situations may require the use of respirators to control exposure. Respirators must be worn if the ambient concentration of dimethylamine exceeds prescribed exposure limits. Respirators may be used (1) before engineering controls have been installed, (2) during work operations such as maintenance or repair activities that involve unknown exposures, (3) during operations that require entry into tanks or closed vessels, and (4) during emergencies. Workers should only use respirators that have been approved by NIOSH and the Mine Safety and Health Administration (MSHA).

* Respiratory protection program

Employers should institute a complete respiratory protection program that, at a minimum, complies with the requirements of OSHA's Respiratory Protection Standard [29 CFR 1910.134]. Such a program must include respirator selection, an evaluation of the worker's ability to perform the work while wearing a respirator, the regular training of personnel, respirator fit testing, periodic workplace monitoring, and regular respirator maintenance, inspection, and cleaning. The implementation of an adequate respiratory protection program (including selection of the correct respirator) requires that a knowledgeable person be in charge of the program and that the program be evaluated regularly. For additional information on the selection and use of respirators and on the medical screening of respirator users, consult the latest edition of the NIOSH Respirator Decision Logic [NIOSH 1987b] and the NIOSH Guide to Industrial Respiratory Protection [NIOSH 1987a].

PERSONAL PROTECTIVE EQUIPMENT

Workers should use appropriate personal protective clothing and equipment that must be carefully selected, used, and maintained to be effective in preventing skin contact with dimethylamine. The selection of the appropriate personal protective equipment (PPE) (e.g., gloves, sleeves, encapsulating suits) should be based on the extent of the worker's potential exposure to dimethylamine. The resistance of various materials to permeation by dimethylamine is shown below:

(*) Not recommended, degradation may occur

To evaluate the use of these PPE materials with dimethylamine, users should consult the best available performance data and manufacturers' recommendations. Significant differences have been demonstrated in the chemical resistance of generically similar PPE materials (e.g., butyl) produced by different manufacturers. In addition, the chemical resistance of a mixture may be significantly different from that of any of its neat components.

Any chemical-resistant clothing that is used should be periodically evaluated to determine its effectiveness in preventing dermal contact. Safety showers and eye wash stations should be located close to operations that involve dimethylamine.

Splash-proof chemical safety goggles or face shields (20 to 30 cm long, minimum) should be worn during any operation in which a solvent, caustic, or other toxic substance may be splashed into the eyes.

In addition to the possible need for wearing protective outer apparel (e.g., aprons, encapsulating suits), workers should wear work uniforms, coveralls, or similar full-body coverings that are laundered each day. Employers should provide lockers or other closed areas to store work and street clothing separately. Employers should collect work clothing at the end of each work shift and provide for its laundering. Laundry personnel should be informed about the potential hazards of handling contaminated clothing and instructed about measures to minimize their health risk.

Protective clothing should be kept free of oil and grease and should be inspected and maintained regularly to preserve its effectiveness.

Protective clothing may interfere with the body's heat dissipation, especially during hot weather or during work in hot or poorly ventilated work environments.

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