Often thought of as a modern-day malady, allergic reactions to rubber gloves were first reported in the early 1930s. The number of reported reactions rapidly increased as the consumption of medical gloves rose after the implementation of Universal Precautions during the mid-1980s. The more common reactions--often referred to as allergic contact dermatitis--are caused by processing chemicals found in both natural and synthetic rubbers. The more serious and potentially life-threatening Type I latex allergy is due to proteins only found in natural rubber products. As of 1997, more than 2,300 allergic reactions associated with latex had been reported to the US Food and Drug Administration's (FDA's) MedWatch Program. More than 200 of these reported cases were associated with anaphylaxis, and 17 were fatal. Recent studies of healthcare workers (HCWs) have estimated the prevalence of Type I latex allergy to be as high as 17%.1 Assuming a conservative 10% prevalence, more than 800,000 HCWs in the US have a Type I allergy to latex and 2 million workers may experience allergic contact dermatitis (Type IV) to one of the many chemicals found in the healthcare environment today.
Latex Allergy Defined
Latex allergy is clinically defined as type I (or Immediate) natural rubber latex (NRL) allergy. It is an acquired immune reaction to one or more of the plant proteins inherent to NRL. Remember that NRL is harvested from a tropical tree and contains over 200 proteins and polypeptides.2 However not all of these proteins are associated with latex allergy. In fact, to date, only 10 have been classified as latex allergens.3 To add to the complexity of this problem, not all proteins or allergens are found in all NRL products. In addition, latex-allergic individuals may not react to all latex allergens.
Individuals can become sensitized to NRL by constant exposure through the use of various NRL products including gloves, condoms, balloons, pacifiers, rubber toys, etc. Exposure to NRL proteins often occurs through cutaneous or percutaneous contact; aerosolized contact (respiratory exposure), mucosal contact (exposure to eyes, nose, mouth, vagina, rectum); intraoperative exposure; and hematogenous exposure through stopcocks, rubber stoppers, and intravenous contact.
Type I symptoms can involve the skin, mucous membranes, respiratory tract, gastrointestinal tract, and/or the cardiovascular system. Symptoms can develop rapidly but subside within hours. Because a significant number of individuals are apparently asymptomatic, a detailed medical history is essential to identify risk factors, previously unexplained allergic reactions, or any potentially related symptoms. Individuals who are potentially "at risk" for Type I latex allergy include those who are repeatedly exposed to NRL such as healthcare and latex industry workers, and patients with spina bifida, myelomeningocele, or urogenital defects. The presence of pre-existing allergies can be considered an additional risk factor, particularly allergies to kiwi, avocado, banana, chestnuts, stone fruits, or other cross-reacting plant allergens.
The diagnosis of a Type I latex allergy in an individual should be based on symptom evaluation, medical history and the presence of circulating anti-NRL antibodies. These antibodies can be detected using one of three methods: 1) skin prick testing with a source of NRL, 2) serum immunoanalyses and/or 3) use testing with an NRL product. Unfortunately, due to the lack of standardization of these methods, obtaining a definitive diagnosis of a Type I latex allergy can be challenging.
A skin-prick test is currently considered the most accurate diagnostic method for Type I latex allergy. It is easy to perform, provides quick results (within 15 minutes) and is highly sensitive. Briefly, a patient's arm is pricked through drops of test solution (prepared from NRL gloves or a purified NRL source). A raised red welt at the prick site indicates that the patient is latex allergic. The standardized test reagents available in Europe with known protein and antigen content are still not commercially available in the US. For this reason, physicians often choose serologic testing such as the ImmunoCAP and AlaSTAT tests, which determine the amount of certain anti-NRL protein antibodies present in a patient's serum. For high-risk groups such as spina bifida patients, positive serologic test results are considered quite accurate. Unfortunately, serologic tests are not as sensitive and results can be falsely negative in 20-30% of the individuals tested.3 Finally, in-use provocation testing exposes a patient to an NRL product for a specified time to measure his/her reaction. Because there is a greater risk of anaphylaxis with in-use testing, patients should be monitored closely and the test environment tightly controlled.
Currently, Type I latex allergy is a complex problem with multiple allergens and poorly standardized test methods. Therefore, more recent diagnostic guidelines suggest combining one or more test methods. Multiple test methods are particularly recommended for individuals with symptoms inconsistent with serum test results. For example, combining serologic with skin-prick testing, or using multiple serologic tests.3 In all cases, tests should be accompanied by an in-depth documentation of a patient's history and risk factors.
Allergic Contact Dermatitis
Although often erroneously referred to as "latex allergy," allergic contact dermatitis (ACD) is a common response to the processing chemicals (i.e., thiurams, carbamates, thioureas, thiazoles) found in rubber products. These chemicals can be used in the production of nitrile, neoprene, and natural rubber medical gloves. Other chemicals such as antiseptics, adhesives, disinfectants, and resins also can produce allergic reactions. Known as a Type IV (or delayed) allergy, ACD is an immune-mediated inflammation of the skin that can localized to the skin. Symptoms can take anywhere from minutes to several hours to develop and can persist for weeks. Whether individuals develop ACD is dependent upon individual susceptibility, exposure history, and the allergenic potential of the chemical(s). While not life-threatening, if left mismanaged or untreated, ACD reactions can cause permanent damage to the patient's/user's skin. Therefore, an accurate and complete diagnosis is essential.
The diagnosis of ACD should be based on symptoms, medical history, and a positive skin reaction to test chemicals (known as patch testing). The patch test is typically conducted by a qualified clinician using a standard series of test allergens on the upper back. The patches are applied for 24 to 48 hours, and the skin examined 24, 48, 72, and 96 hours after the patches are removed. Red and inflamed skin under the patch is indicative of an allergy to the applied chemical. While not a perfect method, patch testing is a valuable tool in identifying chemical allergies, particularly when combined with a detailed medical history and symptom survey.
Management of Latex Allergy, ACD
It is vital that patients and HCWs be guided in the proper management of their allergies. Unfortunately, NRL can be found in healthcare products such as surgical or examination gloves, catheters, intubation tubing, anesthesia equipment, masks, etc., and a myriad of consumer products. Identification of NRL products and prevention of subsequent reactions is imperative.
Individuals with a Type I latex allergy should use products made from non-latex alternatives which do not contain NRL proteins. Current choices include nitrile, neoprene, polyurethane, and styrene-based rubber exam and surgical gloves, as well as vinyl exam gloves. Each material is made from a different mixture of chemicals and different base polymers. Some of these materials--such as nitrile and neoprene--are vulcanized (heat-cured) much like natural rubber. Others--such as vinyl, polyurethane, and styrene-based rubbers--are created in solvent-based systems without vulcanization. In addition, a powder-free latex environment should be maintained for latex-allergic workers or patients to minimize aerosolized latex allergens. Such an atmosphere has been shown to reduce their symptoms.4
Institutions and individual practitioners can quickly address the problem of latex allergies by offering workers a combination of education, testing, and alternative glove materials. The Occupational Safety and Health Administration (OSHA) requires that all employers provide non-latex alternatives to allergic staff, in addition to the safe working environment required by worker compensation laws. Furthermore, considering the significant liability that has arisen in association with a latex-induced anaphylaxis or fatality, it may no longer be cost effective to ignore the problem. In a recent study using conservative estimates of HCW disability costs, implementation of latex alternatives were found to be cost saving, even in small clinics and hospitals.5
Although glove-related allergies are not new, the reporting of Type I latex allergy has increased dramatically during the last 20 years. Defined as an immune reaction to the plant proteins in natural rubber latex, a Type I allergy demands an active management and NRL-product avoidance strategy both at a personal and institutional level. Allergic contact dermatitis to one or more chemicals in the healthcare environment is more common, but less life-threatening than a Type I latex allergy. If untreated, the long-term effects of ACD on the skin can compromise a HCW's career.
For both types of allergy, appropriate diagnosis and alternate product selection can be critical. Given the implications of these allergies, it is imperative that HCWs be educated in the risk factors and symptoms, and receive an accurate diagnosis. Furthermore, allergic individuals should be counseled with regard to appropriate product selection both at work and at home.
Changes in government regulations and industry standards may help lower symptom elicitation and sensitization rates. New polymer developments may also increase product choices for allergic individuals looking to substitute NRL with a synthetic rubber product. Research continues into the causes, improved diagnostic methods, and effective control measures for these allergies with the goal of reduced symptoms and sensitization rates.
Curtis P. Hamann, MD, is the CEO and medical director of SmartHealth in Phoenix, Ariz, and has been a member of the Health Industry Manufacturer's Association (HIMA) Latex Task Force. Pamela A. Rodgers, PhD, is a clinical research associate at SmartHealth and has specialized in liver disease studies at Stanford Medical Center. Kim M. Sullivan is vice president of research and development/regulatory affairs at SmartHealth.
Acknowledgements: The authors gratefully acknowledge the editorial assistance of Tina Evans in the preparation of this manuscript.