OSHA Hazard Information Bulletins
July 27, 1990
| MEMORANDUM FOR: |
REGIONAL ADMINISTRATORS |
| FROM: |
THOMAS J. SHEPICH
Director
Directorate of Technical Support |
| SUBJECT: |
Health Hazard Information Bulletin: Acrylamide Exposure
During Chemical Grouting Operations |
The Directorate of Technical Support issues Hazard Information Bulletins
(HIB) in accordance with Occupational Safety and Health Administration (OSHA)
Instruction CPL 2.65 to provide relevant information regarding unrecognized
or misunderstood health hazards, inadequacies of materials, devices,
techniques, and engineering controls. HIB's are initiated based on
information provided by the field staff, and reports and concerns expressed
by safety and health professionals, employers, and the public. Information is
computed based on a thorough evaluation of available facts, literature and in
accordance with appropriate parties. HIB's are used as vehicles for the
dissemination of technical information to OSHA.
The purpose of this bulletin is to alert OSHA field personnel of the
potential for significant skin exposure to acrylamide during chemical
grouting operations. Acrylamide is used in chemical grouting agents for
sealing holes and stopping water infiltration in sewers and manholes. It is
estimated that about one-half million pounds of acrylamide grout is used
annually for this purpose. Chemical grouting is a very dirty operation. In
the United States, municipal workers and contractors working in sewer repair
can be exposed to acrylamide through skin contact and airborne dusts or
vapors. Workers performing acrylamide grouting are estimated to number from
600 to 1000, based on the number of individuals who are certified by the
grouting suppliers to perform acrylamide grouting.
The Occupational Safety and Health Administration has recently taken steps
to better protect employees from the hazards of acrylamide exposure. On
March 1, 1989, OSHA amended its existing Air Contaminants standard, 29 CFR
1910.1000, including Tables Z-1, Z-2 and Z-3. The amendment included making
212 existing Permissible Exposure Limits (PEL) more protective. Acrylamide
was one of the substances that was made more protective for employees.
Its
PEL was lowered to 0.03 mg/m3 from 0.3 mg/m3 (for an 8-hour time-weighted
average, 40-hour workweek) with a skin notation. The skin notation refers to
the potential contribution to the overall exposure by the cutaneous route
including the mucous membranes and the eyes, either by airborne, or more
particularly, by direct contact with the substance.
Health Effects
Potential target organs include the nervous system, the skin, and the eyes.
Symptoms of overexposure include ataxia, numb limbs, tingling of the skin,
muscular weakness, hand sweating, stumbling walk, shaking, slurred speech,
fatigue, lethargy, and irritation of the eyes and skin. In addition to
neurotoxicity, other health effects may include, carcinogenicity,
genotoxicity, reproductive effects, and developmental effects (Preliminary
Assessment of Health Risks from Exposure to Acrylamide, Environmental
Protection Agency (EPA)).
The International Agency for Research on Cancer (IARC) has classified
acrylamide as a possible human carcinogen (Group 2B); the American Conference
of Governmental Industrial Hygienists (ACGIH) lists acrylamide as a suspected
human carcinogen.
EPA Study
Four sites were investigated in the EPA document, Assessment of Airborne
Exposure and Dermal Contact to Acrylamide During Chemical Grouting
Operations. Sites 1 and 2 were manhole sealing operations; Site 3 was a
manhole sewer maintenance operation; and Site 4 was a lateral line
maintenance operation. On three of these four sites, chemical grout mixing
operations were observed.
All acrylamide grouting materials are manufactured outside the U.S. and are
imported into the U.S. from a Japanese company, Nitto Chemical Co., and an
unidentified French company. Also, Polymer Chemicals of Atlanta, GA imports
grouting materials from this French company. According to the EPA, U.S.
manufactures of acrylamide will not sell acrylamide based grout because of
the potential hazards that can occur during its use in grouting operations.
Acrylamide monomer, powder form, for these sites, was imported by Avanti
International Inc., of Webster, TX (AV-100) and Cues Inc. of Orlando, FL
(Q-Seal). It was supplied in 50 pound bags with an inner plastic liner and
pourable spout. Acrylamide - based grouts consist of acrylamide, which
represents 95% of the mixture and a cross-linking agent such as
methylene-bis-acrylamide which represents the remaining 5%.
The powdered grout is mixed with water at the field site. At two of three
sites where mixing operations occurred, the spout was under water when the
material was being mixed and no visible dust was observed. The aqueous grout
solution is prepared so as to contain 10% solids when injected into a sewer
line crack. An activator, such as triethanolamine, is then added to this
solution. A second solution is also prepared consisting of an initiator or
catalyst, such as ammonium persulfate. Once the equipment is positioned, the
solutions are mixed and injected into the crack. Upon injection the
acrylamide polymerizes and the cross-linking agent binds the polymer chain
together, converting the mixture into a gel. During the liquid and gel
phases of the grout operations, the grout is hazardous to the workers because
of the increased potential for dermal contact and absorption through the
skin.
In addition to acrylamide grout, three non-acrylamide based grouts are
available: urethanes, acrylates, and N-methylolacrylamide (NMA). NMA is
reported to be as effective as acrylamide; whereas the effectiveness of
acrylates is reported as questionable. Urethane is a very effective grouting
material. It use has been limited, however, because it requires modification
of equipment and due to its higher viscosity takes more time to apply.
Wipe samples from these studies ranged from 0.002 mg/100cm(2) at the side of
the packer before insertion into the manhole, and up to 7.10mg/100cm(2) on
the side of the acrylamide mixing tank during the manhole sealing operation.
Hand rinse results ranged from none detectable to 6.25 mg acrylamide. Dermal
contact results ranged from 0.006 mg to 12.1 mg acrylamide. Dermal pad
results ranged from none detectable to 6.64 mg acrylamide.
Some breathing zone area samples results were the following:
| Site |
1 |
0.120 |
mg/m(3) |
8-hour TWA |
Maintenance Superior |
| |
1 |
0.003 |
" |
" |
Utility Worker no. 1 |
|
2 |
0.010 |
" |
" |
" "
|
| |
3 |
0.060 |
" |
" |
" " no. 2 |
| |
3 |
0.040 |
" |
" |
Grout Foreman |
| |
3 |
0.050 |
" |
Area Sample |
Near mixing tanks |
| |
4 |
0.008 |
" |
8-hour TWA |
Utility Worker |
| |
4 |
0.070 |
" |
Area Sample |
Near mixing tanks |
| |
4 |
N.D. |
" |
" |
Approx. 20 ft. from service van |
Evaluation Methods
OSHA's sampling method requires the use of a 13mm glass fiber filter (GFF)
in a Swinnex (TM) cassette followed by a silica gel tube (150/75mg sections,
20/40). The glass fiber filter and gaskets must be desorbed in 1 ml methanol
as soon as possible after sampling and submitted as a separate sample.
This
method has been used for 10 years.
For a quantitative wipe sampling result, a dry glass fiber filter should be
used for acrylamide wipe samples. Either one or two milliliters of methanol
should be added to a vial before the dry glass fiber filter is placed into
it. The amount of methanol used must be reported to the Salt Lake City
Laboratory. A qualitative result can also be obtained by wetting the filter
with a few drops of methanol before taking the wipe sample and placing it in
a dry container.
Protective Equipment
OSHA compliance officers should be aware of the hazards of acrylamide during
sewer grouting operations in order to avoid potential exposures to themselves
as well as employees. Protective clothing can include full protective
clothing made of polyethylene-ethylenevinyl-alcohol-polyethylene (PE/EVOH/PE)
and rubber gloves, safety glasses, coveralls, aprons, boots, goggles and face
shields.
Compliance officers should exercise professional judgement, based on
expected exposure and environmental conditions, in selecting appropriate
personal protective equipment. Heat stress must be taken into consideration
and confined space procedures should be followed.
Controls
Proper engineering controls, work practices, decontamination procedures,
protective clothing and respirators should be utilized. Engineering controls
should include general ventilation and local exhaust ventilation where
appropriate.
Significant dermal contact can result from this type of operation. Where
there is a potential for skin contact, adequate protective clothing should be
worn and protective skin preparations (barrier creams) should be used to
minimize skin absorption.
Please disseminate this bulletin to all Area Offices, State Plan States and
Consultation Project Officers.
BIBLIOGRAPHY
Environmental Protection Agency (EPA). July 1987. Assessment of
Airborne Exposure and Dermal Contact to Acrylamide Chemical Grouting
Operations. No. 560/5-87-009, Office of Toxic Substances. EPA:
Washington, D.C.
EPA. March 1990. Preliminary Assessment of Health Risks from Exposure to
Acrylamide. Office of Toxic Substances. EPA: Washington, D.C.
International Agency for Research on Cancer (IARC). 1987. IARC
Monographs on the Evaluation of Carcinogenic Risk to Humans. Supplement
7. IARC: Sheridan, N.Y.
National Institute for Occupational Safety and Health (NIOSH). September
1986. Evaluation of Occupational Acrylamide Exposures. Allied Industrial
Hygiene. 1(3):148-152.
NIOSH/OSHA Occupational Health Guidelines for Chemical Hazards on
Acrylamide. January 1981. DHHS, NIOSH #81-123. NIOSH: Cincinnati.
NIOSH Pocket Guide to Chemical Hazards. 1986. DHHS, NIOSH #85-114.
NIOSH: Cincinnati.
Occupational Safety and Health Administration (OSHA). March 1989.
Industrial Exposure and Control Technologies for OSHA Regulated Hazardous
Substances. Vol. 1 of 2. OSHA: Washington, D.C.
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