Safety Comes First

Safety Comes First

John Preston 2812 Northampton St., N.W., Washington, DC 20015

This column is provided to address items of concern regarding safety aspects of model aviation activities. Content of the column, however, is the opinion of the author and does not necessarily represent the official position of the Academy of Model Aeronautics.

Potential health hazards in the use of "instant" (CyA) glues — revisited

CYANOACRYLATE GLUE. This month's Safety column is a reprint of the one which appeared in the October 1985 issue of Model Aviation and was entirely devoted to the possible health hazard presented by the use of CyA glue.

In the eight years that I've been writing this column, I have never previously "recycled" an entire column. The reason I'm doing it now is because of the many letters I received from modelers who asked for copies of that October 1985 column when I mentioned in my January 1988 column that such were available upon request. To those of you who have been readers since before October 1985, I apologize for this repeat. However, I think the following material is sufficiently important to new AMA members (and those others who may not have seen it previously) to justify this rerun.

Can use of CyA glue pose a health hazard—or not? There have been a number of articles in model magazines and even more in club newsletters that have alleged that cyanoacrylate ("instant") glues may represent a health hazard to the user. This column has previously reprinted numerous accounts from readers who have related tales of sticking various body parts together while using such glues; but, by now, I think all readers must be well aware of this minor problem. This is not what I am going to address in this column.

Back in the April 1985 issue of Model Aviation, I quoted excerpts from a letter from Roy McGuckin who stated that he had to stop using CyA glue because of the problems he had experienced. These were severe lung congestion and a "hivelike" itching all over the body. Since the publication of Roy's experiences in this column, numerous other readers have called or written to describe similar symptoms. On the basis that "there is no smoke without a fire," I decided to try and track down these allegations that the symptoms were the result of using CyA glue.

I sent letters to three hobby distributors of CyA glue and one to the Center for Occupational Hazards in New York City. My letters described the symptoms that modelers had outlined in their letters to me, and I asked for comments on whether these symptoms really could be the result of using CyA glue products.

Responses from distributors and experts

• All replies emphasized the need for ADEQUATE VENTILATION when using cyanoacrylate glue.
• The Center for Occupational Hazards stated: "Both common cyanoacrylates (methyl-2 and ethyl-2-cyanoacrylate) are incredibly irritating, causing tearing of the eyes and damage to the membranes of the respiratory system."

One hobby distributor sent a summary of a study by Eastman Kodak Company. In that study, 14 individuals were deliberately exposed to vapors from cyanoacrylates. The results showed the odor from the cyanoacrylate is perceptible at about 1 part per million (ppm) for some subjects, with a range of 1 to 5 ppm. Throat and nose irritation usually began at about 2 to 3 ppm, with a reported range of 2 to 20 ppm. Based on these studies, the researchers concluded that exposures should probably be limited to levels of 3 ppm or less. This aligns with a Material Safety Data Sheet for a specific ethyl-2-cyanoacrylate product, which recommends a Threshold Limit Value (TLV) of 2 ppm.

How this relates to hobbyist workshops

• The Center for Occupational Hazards commented that it is highly unlikely hobbyists working in ordinary home and studio environments can keep exposures below these levels if they work very long. Overexposure can cause respiratory irritation sufficient to cause stuffiness and discomfort and can leave the respiratory tract susceptible to colds and infections.
• The recommendation: use some exhaust ventilation, such as working in front of a window exhaust fan, when working with this glue.

Medical evidence: asthma case report Several readers who experienced breathing difficulties reported that their doctors were skeptical about linking their problems to CyA glue, due in part to limited information in the medical literature. However, the May 1985 issue of Annals of Internal Medicine (Vol. 102, No. 5, pp. 613–615) published a case report titled "Asthma Due to Ethylcyanoacrylate Instant Glue" by physicians from the University of Cincinnati Medical Center.

Summary of the case:

• A 32-year-old man developed asthma after about a year of using ethylcyanoacrylate adhesive while building remote-control model airplanes.
• Typical asthma and rhinitis symptoms developed and were consistently related to applying the glue to balsa wood.
• Bronchial provocation by glue vapors, simulating home exposure, produced a late asthmatic response with rhinorrhea (runny nose) and lacrimation (tearing).
• Increased bronchial hyper-reactivity to methacholine occurred after bronchial challenge and persisted for several weeks.
• Complete resolution of the patient's asthma symptoms occurred with avoidance of the glue. Reversion to a negative methacholine challenge test occurred after six months of continued avoidance.

Additional details from the report:

• Symptoms (shortness of breath, puffy lips, rhinorrhea) developed 30 minutes to 1.5 hours after applying the glue in a confined area. Wheezing, dyspnea, and chest tightness occurred 3 to 5 hours later, often awakening him at night. Profuse watery rhinorrhea was noted 12 to 24 hours after exposure.
• The patient had a strong family history of allergy and asthma and had positive skin tests for grasses and feathers. He smoked a pack of cigarettes a day for five years but had no other hobbies or occupational allergens implicated.
• The patient was tested under controlled conditions in a clinical research center and subjected to CyA glue vapors while monitored; his symptoms were reproduced.
• The authors concluded the asthma was due to exposure to ethylcyanoacrylate vapors and emphasized that avoidance resulted in resolution of symptoms. They advised that medical personnel and hobbyists should be aware of the potential for respiratory sensitization from these adhesives.

Skin irritation and dermatitis

• Several readers reported skin irritation allegedly due to CyA exposure. One described "severe itching all over my body." Another, a police officer who uses cyanoacrylate in an airtight tank to enhance fingerprints, reported opening the tank before exhausting fumes and being struck full in the face with concentrated CyA fumes. He developed large red patches and severe itching that lasted five days and required dermatologist treatment.
• A paper titled "Cyanoacrylate Dermatitis" in Contact Dermatitis (a British journal) described an outbreak of irritant dermatitis among electronic assemblers. One man had isolated exposure to an unventilated open tank of cyanoacrylate; several workers were severely affected. The paper concluded simple ventilation would have prevented the outbreak.
• The Contact Dermatitis article summarized symptoms in five female workers who experienced facial skin irritation. In that plant, workers were sealing wires at the bottom of a small metal box and also used a soldering iron. The glue polymerizes almost instantaneously in the presence of moisture, but if a soldering iron burns excess glue it may vaporize monomer and produce eye stinging or skin irritation. The manufacturer warned that soldering burning the glue may cause vaporization and should be avoided.

Role of humidity

• The outbreak described in Contact Dermatitis was associated with low relative humidity (30–40%). When the relative humidity was raised above 55% by installing humidifiers, no further skin complaints occurred.
• Reports of skin irritation from model-building use of CyA appear fewer than respiratory complaints. This might mean either skin irritation from CyA vapors is less likely, or most modelers work at relative humidity above 55%.

Other concerns addressed

• Claims that cyanide gas is produced when CyA polymerizes, or that baking soda used to fill a joint can release cyanide gas, are false.
• Allegations that CyA is a carcinogen are unfounded. Oral toxicity studies in albino rats indicate cyanoacrylates are not considered a toxic substance as defined by the Federal Hazardous Substances Act.

Practical recommendations

• Use adequate ventilation: work near an exhaust fan or open window with ventilation.
• If exhaust ventilation is not practical, consider a respirator with appropriate chemical/carbon filters (discuss options with a safety supplier).
• Avoid direct skin contact with glue; use gloves when appropriate.
• Rinse eyes immediately with water and seek prompt medical attention if glue enters the eye.
• If you commonly perform soldering or otherwise heat areas where CyA has been applied, avoid inhaling fumes produced by burning the adhesive.
• If you experience persistent respiratory or dermatologic symptoms that you suspect are related to cyanoacrylate exposure, consult a physician and consider obtaining the medical literature on reported cases.

For readers wishing to read the entire medical case report, it can be obtained from Stuart M. Brooks, M.D., University of Cincinnati Medical Center, Mail Location 182, Cincinnati, OH 45267.

Conclusion Although many hobbyists use cyanoacrylate glues without experiencing significant problems, there are documented cases of respiratory sensitization and skin irritation. Use common sense, provide adequate ventilation or personal protection, and you should minimize the risk of problems.

Transcribed from original scans by AI. Minor OCR errors may remain.