Disclaimer: The information contained in these
guidelines is intended for reference purposes only. It provides a
summary of information about chemicals that workers may be
exposed to in their workplaces. The information contained in
these guidelines is current as of date of publication (September,
1996); recommendations may be superseded by new developments in
the field of industrial hygiene. Readers are therefore advised to
regard these recomendations as general guidelines and to
determine whether new information is available.
OCCUPATIONAL SAFETY AND HEALTH GUIDELINE FOR TRICHLOROACETIC ACID
INTRODUCTION
This guideline summarizes pertinent information about trichloroacetic
acid 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 Recommendations may be superseded by new developments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)HCl(3)O(2)
* Structure
(For Structure, see paper copy)
* Synonyms
Aceto-caustin, TCA, trichloroethanoic acid, trichloracetic acid,
amchem grass killer
* Identifiers
1. CAS No.: 76-03-9
2. RTECS No.: AJ7875000
3. DOT UN: 1839 59; 2564 59 (Solution)
4. DOT label: Corrosive
* Appearance and odor
Trichloroacetic acid is a colorless, deliquescent, nonflammable,
crystalline solid. It has a sharp, pungent odor and is a relatively
strong acid.
CHEMICAL AND PHYSICAL PROPERTIES
* Physical data
1. Molecular weight: 163.38
2. Boiling point (at 760 mm Hg): 197.5 degrees C (387.5 degrees F)
3. Specific gravity: 1.62 at 25 degrees C (77 degrees F)
4. Vapor density: Data not available.
5. Melting point: 58 degrees C (136.4 degrees F)
6. Vapor pressure at 51 degrees C (124 degrees F): 1 mm Hg
7. Solubility: Soluble in water, ethanol and diethyl ether.
8. Evaporation rate: Data not available.
* Reactivity
1. Conditions contributing to instability: The deliquescent crystals
will readily absorb moisture forming a corrosive acidic solution.
2. Incompatibilities: Contact between trichloroacetic acid and moisture,
bases, strong oxidizing agents, strong reducing agents, iron, zinc,
aluminum, and alkali metals such as sodium, potassium, and calcium
should be avoided.
3. Hazardous decomposition products: Toxic gases such as chloroform,
chlorine, hydrogen chloride, hydrochloric acid, carbon dioxide, and
carbon monoxide may be released in a fire involving trichloroacetic
acid.
4. Special precautions: Keep containers sealed to avoid contact between
trichloroacetic acid and moisture.
* Flammability
Trichloroacetic acid is not combustible.
The National Fire Protection Association has not assigned a
flammability rating to trichloroacetic acid.
1. Flash point: Data not available.
2. Autoignition temperature: Data not available.
3. Flammable limits in air: Data not available.
4. Extinguishant: For small fires use dry chemical, carbon dioxide,
water spray, or regular foam. Use water spray, fog, or regular foam
to fight large fires involving trichloroacetic acid.
Fires involving trichloroacetic acid should be fought upwind from the
maximum distance possible. Keep unnecessary people away; isolate the
hazard area and deny entry. Emergency personnel should stay out of
low areas. Containers of trichloroacetic acid 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 chemical protective clothing and
self-contained breathing apparatus when fighting fires involving
trichloroacetic acid.
EXPOSURE LIMITS
* OSHA PEL
The Occupational Safety and Health Administration (OSHA) does not
currently regulate trichloroacetic acid.
* NIOSH REL
The National Institute for Occupational Safety and Health (NIOSH) has
established a recommended exposure limit (REL) for trichloroacetic
acid of 1 part per million (ppm) parts of air (7 milligrams per cubic
meter (mg/m3)) 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 trichloroacetic acid a threshold limit value (TLV) of 1
ppm (6.7 mg/m3) as a TWA for a normal 8-hour workday and a 40-hour
workweek [ACGIH 1994, p. 34].
* Rationale for Limits
The NIOSH limit is based on the risk of eye and skin irritation [NIOSH
1992].
The ACGIH limit is based on the risk of eye and upper respiratory
tract irritation [ACGIH 1991, p. 1603].
HEALTH HAZARD INFORMATION
* Routes of Exposure
Exposure to trichloroacetic acid can occur through inhalation,
ingestion, and eye or skin contact.
* Summary of toxicology
1. Effects on Animals: Trichloroacetic acid is a skin and eye irritant,
and also affects the kidneys and liver of experimental animals. It
was shown to be a liver carcinogen in a single study in mice [ACGIH
1991]. When trichloroacetic acid was instilled into the eye of
rabbits, severe irritation was observed characterized by severe and
extensive loss of epithelium and endothelium, infiltration and
hemorrhage about the limbal vessels, infiltration and hyperemia of the
iris, and damage to the anterior layers of the lens [ACGIH 1991].
Trichloroacetic acid is a mild skin irritant in rabbits [NIOSH 1991].
The oral LD(50) in rats is 400 mg/kg [NIOSH 1991]. Animals poisoned
by oral doses of trichloroacetic acid quickly passed into a state of
narcosis or semi-narcosis, and within 36 hours they either recovered
completely or died [ACGIH 1991]. Male rats administered 50, 500, or
5,000 ppm trichloroacetic acid in their drinking water for 90 days
developed a significant increase in relative kidney weight, and a
significant increase in hepatic peroximal beta oxidation activity and
focal areas of hepatocellular hypertrophy [ACGIH 1991].
Trichloroacetic acid ingestion had no effect on serum biochemical
parameters or on parameters of immune function [ACGIH 1991].
Trichloroacetic acid was not mutagenic in the Ames assay in the
presence and absence of metabolic activation. It showed some activity
in in vivo tests of genotoxicity [ACGIH 1991]. In a chronic study,
mice were administered trichloroacetic acid in the drinking water at
concentrations of 2,000 or 5,000 ppm for 61 weeks. Both dose levels
of trichloroacetic acid induced hepatocellular carcinomas and adenomas
[NLM 1992; ACGIH 1991]. Trichloroacetic acid was not carcinogenic in
rats (details of this study were not provided) [ACGIH 1991].
2. Effects on Humans: Trichloroacetic acid is irritating and corrosive
to the skin, eye, and mucous membranes in humans, but is not readily
absorbed through the skin [ACGIH 1991]. Trichloroacetic acid can
denature protein and precipitate protein and may cause chemical burns
to tissue [ACGIH 1991]. The extent of the damage caused is dependant
upon the concentration of the material and the duration of the
exposure.
* Signs and symptoms of exposure
1. Acute exposure: Acute exposure to trichloroacetic acid may cause
severe irritation and/or chemical burns to the eyes, skin, and mucous
membranes. Inhalation may result in choking, coughing, dizziness,
weakness, or swelling of the throat and lungs [Sittig 1991].
2. Chronic exposure: No signs or symptoms of chronic exposure to
trichloroacetic acid have been reported in humans. Chronic exposure
is expected to cause persistent cough and possibly digestive tract
disturbances [Sittig 1991].
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 trichloroacetic acid and lead to
worker exposures to this substance:
* The manufacture and transportation of trichloroacetic acid
* Use as a medication, in organic synthesis, in the manufacture of
herbicides, and as a reagent
Methods that are effective in controlling worker exposures to
trichloroacetic acid, 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 trichloroacetic acid 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
trichloroacetic acid, 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, and respiratory system.
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 trichloroacetic acid 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, or respiratory system.
* 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
trichloroacetic acid exposure. The interviews, examinations, and
medical screening tests should focus on identifying the adverse
effects of trichloroacetic acid on the eyes, skin, or respiratory
system. 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. Trichloroacetic acid can be detected in the blood and
urine of exposed workers. However, no biological monitoring test
acceptable for routine use has yet been developed for trichloroacetic
acid.
WORKPLACE MONITORING AND MEASUREMENT
Determination of a worker's exposure to airborne trichloroacetic acid
is made using a silica gel tube (150/75 mg sections, 20/40 mesh).
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 deionized water. Analysis is conducted by high
performance liquid chromatography using an ultraviolet detector
(HPLC/UV). This method is described in the OSHA Computerized
Information System [OSHA 1994] and is partially validated.
PERSONAL HYGIENE PROCEDURES
If trichloroacetic acid contacts the skin, workers should flush the
affected areas immediately with large amounts of water; direct the
water under contaminated clothing while removing the clothing so the
acid is quickly removed.
Clothing contaminated with trichloroacetic acid 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 trichloroacetic acid,
particularly its potential for causing eye and skin irritation and
tissue corrosion.
A worker who handles trichloroacetic acid 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 trichloroacetic acid or a solution
containing trichloroacetic acid is handled, processed, or stored.
STORAGE
Trichloroacetic acid 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 trichloroacetic acid should be protected from physical damage and
moisture, and should be stored separately from bases, strong oxidizing
agents, strong reducing agents, iron, zinc, aluminum, and alkali
metals such as sodium, potassium, and calcium.
SPILLS AND LEAKS
In the event of a spill or leak involving trichloroacetic acid,
persons not wearing protective equipment and fully-encapsulating
vapor-protective clothing should be restricted from contaminated areas
until cleanup has been completed. The following steps should be
undertaken following a spill or leak:
1. Do not touch the spilled material; stop the leak if it is possible to
do so without risk.
2. Notify safety personnel.
3. Cover small spills with excess sodium bicarbonate to neutralize the
material.
4. Use caution to prevent generating dust clouds or dispersing the
material into the air.
5. Use water spray to reduce vapors.
6. For small liquid spills, take up with sand or other noncombustible
absorbent material and place into closed containers for later
disposal.
7. For large liquid spills, build dikes far ahead of the spill to contain
the trichloroacetic acid 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
Trichloroacetic acid 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].
Employers are not required by the emergency release notification
provisions in 40 CFR Part 355.40 to notify the National Response
Center of an accidental release of trichloroacetic acid; there is no
reportable quantity for this substance.
* 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 trichloroacetic acid 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. Although
trichloroacetic acid is not specifically listed as a hazardous waste
under RCRA, EPA requires employers to treat waste as hazardous if it
exhibits any of the characteristics discussed above.
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 trichloroacetic acid
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 trichloroacetic acid. 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 trichloroacetic acid.
The resistance of various materials to permeation by trichloroacetic
acid is shown below:
Material |
Breakthrough time (hr) |
nitrile rubber |
>4 |
polyethylene |
Caution 1 to 4 |
saranex |
Caution 1 to 4 |
To evaluate the use of these materials with trichloroacetic acid,
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 trichloroacetic acid .
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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Conference of Governmental Industrial Hygienists.
ACGIH [1994]. 1994-1995 Threshold limit values for chemical
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ATS [1987]. Standardization of spirometry -- 1987 update. American
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Materials Transportation, Research and Special Programs
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Forsberg K, Mansdorf SZ [1993]. Quick selection guide to chemical
protective clothing. New York, NY: Van Nostrand Reinhold.
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Genium Publishing Corporation.
Mickelsen RL, Hall RC [1987]. A breakthrough time comparison of
nitrile and neoprene glove materials produced by different glove
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Human Services, Public Health Service, Centers for Disease Control,
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Trenton, NJ: New Jersey Department of Health.
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Bethesda, MD: National Library of Medicine.
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