|<< Back to OSHA Safety and Health Information Bulletins - Table of Contents|
OSHA Safety Hazard Information Bulletin on
Acrylamide Exposure During Chemical Grouting Operations
July 27, 1990
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.
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.
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:
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.
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.
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.
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.