Understanding Latex Allergy And Glove Chemistry By Edward Lehrman, MD (written ~August 29, 1996) Selecting The Right Glove: Understanding Latex Allergy And Glove Chemistry Over the past few years, there has been an increasing incidence of allergic reactions among health care workers to latex medical gloves. Current estimates on the prevalence of latex allergy among health care workers range as high as 17%. This is thought to be largely due to the institution of universal precautions in response to the AIDS epidemic, and the resultant dramatic increase in glove usage. A large body of literature on this subject has built up in the allergy, immunology, and nursing journals, but there have been relatively few publications in the surgical literature, so many surgeons and surgical subspecialists remain relatively ignorant in this area. This review will summarize the most important findings from this literature from the point of view of the glove user (the surgeon and nurse). A major theme of this monograph is that a latex glove, like all medical devices, has benefits as well as risks. There are potential side effects from this device, and the surgeon needs to consider these in making his or her choice of surgical glove. I hope to cover: 1. What characteristics should we look for in a glove? 2. What types of allergic reactions can occur? 3. Basic information about rubber (natural latex and synthetic) and how gloves are made You should understand what it is that you are putting against your skin. It is important to consider the risk of allergic sensitization when selecting gloves rather than just choosing the lowest cost item available, or simply relying on the hospital purchasing department to make the appropriate choice for you. I am going to focus on sterile gloves for use in surgery, but remember that non-sterile examination gloves for use in the office are important to evaluate as well. What glove characteristics should we look for? There are several important considerations. First, gloves offer barrier protection both for the health care worker and the patient to guard against contact with blood, other body fluids, and microorganisms. Latex has been in use for about 100 years, and has proven barrier protective capability. In a series of studies, Korniewicz and co-workers9,10,11 have shown that vinyl gloves have higher leakage rates than latex (less barrier effectiveness), and are therefore less suitable for surgery. They reported that although both vinyl and latex examination gloves provide protection to the user, latex gloves maintain their integrity longer under in-use conditions. The barrier effectiveness of synthetic rubber gloves is not as well established at this time as for latex. 18 Second, a glove needs to be comfortable. One should be able to don it (slip one’ s hand into it) easily, and then be able to perform surgery as if you weren’ t even wearing a glove at all. Again, latex excels - the synthetic materials are frequently stiffer than latex, and less comfortable to wear. Third, cost is important. Latex gloves are usually less expensive than synthetic rubber gloves. So latex has substantial benefits as a material for surgical gloves. What are the risks? Latex Allergy A latex glove contains natural latex, cornstarch powder frequently (added to help the surgeon don the glove), and numerous chemicals, some of which will be discussed below. These are foreign matter, and the human immune system sometimes responds. There are 3 major types of reactions. 1. Irritant dermatitis - This is skin irritation that does not involve the body’s immune response. It is not an allergic response. Some causes include: frequent hand washing and inadequate drying, aggressive scrubbing technique or detergents, mechanical abrasive effect of glove powder, climatic irritation (cold climates can cause dry, chapped skin and hot weather can cause excessive sweating), and emotional stress. Even though this is not an allergic reaction, irritant hand dermatitis can cause breaks in the skin which can allow easier entry of the sensitizing latex protein or glove chemicals, and in turn lead to latex allergy. Fay 5 provides a review of irritant dermatitis and its management. 2. Delayed cutaneous hypersensitivity (type IV allergy) - This is a contact (hand) dermatitis generally due to the chemicals used in latex glove production. It is mediated via T -cells. The skin reaction is typically seen 6-48 hours after contact. The reaction is local and limited to the skin that has contacted the glove. While not life threatening, those with type IV allergy are at increased risk to develop type I allergy. One route of sensitization, for example, is that latex proteins are more easily able to enter the body through the broken skin barrier. 3. Immediate reaction (type I allergy) - These are systemic allergic reactions caused by circulating IgE antibodies to the proteins in natural latex. Symptoms include hives, rhinitis, conjunctivitis, asthma due to bronchoconstriction, and in severe cases anaphylaxis and hypotension. Symptoms occur soon after exposure to latex (within about 30 minutes). There are several routes of exposure that can lead to type I sensitivity: cutaneous, mucosal, parenteral, and aerosol (from inhaling latex glove powder). There are several groups of people known to be at increased risk for latex allergy: patients who have had multiple hospitalizations and been exposed numerous times to latex medical products (especially patients with spina bifida), health care workers, and workers in the rubber industry. Current estimates are that 8-17% of health care workers become sensitized. The recent emphasis on universal precautions, with a concomitant marked increase in glove usage, is largely blamed for the increase in allergy among health care workers. Atopic individuals (those with other allergies or asthma) are at significantly greater risk to develop latex allergy than the general population. It is estimated that as many as 25-30% of atopic health care workers may become sensitized. Another major issue is the cornstarch powder that has long been used in latex gloves. Researchers have shown in several papers 3,4 that cornstarch powder binds the latex protein in the surgical glove, which allows the antigen to reach both the wearer’ s skin more easily (when the hand becomes moist during surgery) and the patient’ s skin. Also, when the surgeon both dons and removes the glove, cornstarch powder is released into the air, and this becomes a significant source of aerosolized latex protein that can sensitize health care workers via inhalation. In a separate study done at the Mayo Clinic, 19 latex aeroallergen concentrations varied from 10 to 208 ng/m 3 in areas where powdered latex gloves were used compared to 0.3 to 1.8 ng/m3 in areas where powdered latex gloves were never or seldom used. Donald Beezhold has also written that body sweat inside latex gloves may make latex proteins soluble, allowing absorption through skin and sensitizing the wearer.4 He has reported that the amount of free latex protein that can be extracted from powdered latex gloves is consistently higher than the amount that is liberated from non-powdered gloves. 4,12 He has suggested that cornstarch powdered latex gloves should be eliminated. 2 Here is another thing to remember: not all latex gloves are created equal. There are significant (sometimes astounding) differences between manufacturers and product lines in the amount of free latex protein that can be liberated from the glove and the number and types of chemicals used in glove production. Also, gloves can be soaked after production to try to leach out the protein and chemicals, and once more there will be differences between manufacturers in how effectively these are removed. There is literature that clearly shows that some brands of gloves are more allergenic than others. 21 How are gloves made? Now on to some material about rubber in general and how gloves are made. 1,14,15,20 This will be brief - a more detailed review at a level that a physician or nurse can understand is the article by Truscott. 20 In order to make a surgical glove, in addition to latex, one needs water, vulcanizing agents, accelerators, activators, blockers, retarders, anti-oxidants, preservatives, odorants, colorants, stabilizers, and processing aids. In other words, you need a veritable chemical soup. Natural latex is a polymer - that is, it is a long molecule composed of many repeating smaller molecular units. The basic unit of the polymer is called isoprene (synthetic rubbers use different chemicals as the basis for creating the polymer). Charles Goodyear first discovered a process that made rubber commercially useful. The story is that he accidentally dropped a mixture of rubber and sulfur into a fire. This produced a material that was no longer sticky, and had many desirable physical characteristics. Goodyear named this process vulcanization, after Vulcan, the Roman god of fire and craftwork. Vulcanized rubber is stronger yet also more elastic than the starting material. The sulfur cross-links the polymer chains in the latex. You can stretch vulcanized latex, but the polymer chains then snap back so the product returns to its original shape. Nowadays, latex gloves are not produced with sulfur and fire. But sulfur is still very important as the primary vulcanizing agent. Accelerators are chemicals that speed the cross-linking process, either by donating sulfur atoms or because they are soluble within the natural rubber and help to draw the sulfur into the rubber by binding with sulfur. The major accelerators (and these are very important because they all can cause type IV allergy) are: thiurams, mercaptobenzothaizoles (usually abbreviated MBTs), and carbamates. A second group of chemical sensitizers is the anti-oxidants. These are added to decrease the rate of rubber degradation. A wide variety of chemicals are available - glove manufacturers primarily use substituted phenols. It is important to realize that different gloves will have different chemicals in differing concentrations in the final product. Also, since latex is a natural product, there will be some variation in the protein content from one lot to the next. One brief comment about the word hypoallergenic - ignore it. The FDA proposed regulations in the summer of 1996 (which are not yet finalized as of this writing) that manufacturers not be permitted to use this term, since there is no established safe level below which latex protein or glove chemicals might not be harmful. Gloves are created by dipping forms (which look like hands) into vats of liquid latex and admixed chemicals. The latex glove then hardens on the mold - it is formed with what will ultimately be the inside of the glove (touching your skin) on the outside of the mold. Then the gloves, still on the mold, go through one or more rinses to leach out protein and residual chemical (better rinsing equals less residua). Finally, the finished product is stripped off the mold, packaged, and sterilized. Conclusions Clearly, we need gloves that provide excellent barrier protection, surgeon comfort, and acceptable cost. I would add that the literature indicates that the ideal glove, if it is latex, should be powder free, very low in extractable latex protein, and have the smallest concentration and the fewest number of residual chemicals from manufacture 6,18 Even when considering glove selection from the cost side alone, the cost at the time of purchase is only one part of the equation. As Fay 7 points out, failed (torn) gloves cost the hospital money for replacement and waste removal, and one needs to consider the very real costs of providing the more expensive synthetic gloves for workers who become sensitized to latex or the major costs of disability payments for those who become so seriously sensitized that they are occupationally disabled.8,18 The risk of serious allergic reactions in patients who are already sensitized to latex must not be overlooked. Alternately, the surgeon might consider that perhaps the ideal surgical glove is a synthetic rubber, such as polychloroprene (Neoprene) or one of the copolymers that contain styrene and butadiene. But there are pitfalls to this approach as well. The barrier properties of nonlatex synthetic rubber gloves are not as clearly defined. The cost of the synthetics is greater. The user still needs to pay attention to the chemical composition of the glove, because dangerous type IV reactions are possible. And the surgeon who chooses synthetic rubber gloves should be prepared to potentially sacrifice on glove comfort, dexterity, and grip because the fit, feel, and elasticity of the synthetic materials differ from natural rubber latex. Glove choice should also be appropriate to the situation. One should consider wearing non- latex gloves (such as vinyl) when the superior barrier protection of latex is not needed. So, for example, a very short (less than 10-15 minute) procedure with minimal prospect for blood or body fluid contact might be one for which a vinyl glove could be considered an acceptable choice. Non-latex gloves may also be appropriate for the nurse who preps the surgical site prior to the start of surgery if the patient’ s skin is intact, making body fluid contact highly unlikely. In addition, here are a few common sense reminders. 13 Prior to use, medical gloves should not be stored under conditions of excess heat or light, nor be near sources of ionizing radiation, since this will cause more rapid rubber degradation. Health care workers should be sure to remove gloves promptly when completing a procedure, and then wash his or her hands after glove use to minimize skin contact time with potential allergens. Also, health care workers should avoid touching their eyes, noses, or mouths while wearing latex or immediately upon removing a latex glove, in order to avoid potential latex sensitization via these mucosal routes. References 1. "Barrier protection, the hands on experience: clinical reference manual." Ansell Perry Corporation. 2. Beck, W. & Beezhold, D. Starch glove powder should follow talc into limbo. Journal of the American College of Surgeons 178: 185-186, 1994. 3. Beezhold, D. & Beck, W.C. Surgical glove powders bind latex antigens. Archives of Surgery 127: 1354-1357, 1992. 4. Beezhold, D., Kostyal, D., & Wiseman, J. The transfer of protein allergens from latex gloves: a study of influencing factors. AORN Journal 59: 605-613, 1994. 5. Fay, M.F. Hand dermatitis. AORN Journal 54 (3): 451-467, 1991. 6. Fay, M.F. Gloves: problems, pitfalls, and prevention. Infection Control and Sterilization Technology 2 (1): 23-28, 1996. 7. Fay, M.F. & Dooher, D.T. Surgical gloves: measuring cost and barrier effectiveness. AORN Journal 55 (6): 1500-1519, 1992. 8. "Guidelines for latex glove users." Occupational Health and Safety Branch, Ontario Ministry of Labor. Toronto, Canada. 9. Korniewicz, D.M., Laughon, B.E., Butz, E., & Larson, E. Integrity of vinyl and latex procedure gloves. Nursing Research 38 (3): 144-146, 1989. 10. Korniewicz, D.M., Laughon, B.E., Cyr, W.H., Lytle, C.D., & Larson, E. Leakage of virus through used vinyl and latex examination gloves. Journal of Clinical Microbiology 28 (4): 787- 788, 1990. 11. Korniewicz, D., Kirwin, M., Cresci, K., & Larson, E. Leakage of latex and vinyl exam gloves in high and low risk clinical settings. American Industrial Hygiene Association Journal 54 (1): 22-26, 1993. 12. Patterson, P. Allergy issues complicate buying decision for gloves. OR Manager, June 1995. 13. Reis, J. Latex Sensitivity. AORN Journal 59 (3): 615-621, 1994. 14. "Rubber." Microsoft Encarta, 1993. 15. "Rubber, natural and synthetic." Compton’s Interactive Encyclopedia, 1994. 16. Sosovec, D. Hand care protocol. Baxter Healthcare Corporation. 17. Sussman, G.L. & Beezhold, D.H. Allergy to Latex Rubber. Annals of Internal Medicine, 122 (1): 43-46, 1995. 18. Sussman, G.L. & Beezhold, D.H. Safe use of natural rubber latex. Allergy and Asthma Proceedings 17 (2): 101-102, 1996. 19. Swanson, M.C., Bubak, M.E., Hunt, L.W., Yunginger, J.W., Warner, M.A., & Reed, C.E. Quantification of occupational latex aeroallergens in a medical center. Journal of Allergy and Clinical Immunology 94: 445-451, 1994. 20. Truscott, W. The industry perspective on latex. In Fink, J. (ed). Immunology and Allergy Clinics of North America 15 (1), 1995. 21. Turjanmaa, K., Laurila, K., Makinen-Kikjunen, S., & Reunala, T. Rubber contact urticaria. Contact Dermatitis 19: 362-367, 1988.