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By Kathy Dix
When latex allergies first became prevalent in the early 1990s, there weremany misconceptions about what actually defined an allergy. Many healthcareworkers (HCWs) who assumed they were allergic to latex actually had developedirritant contact dermatitis, not a true allergy.
The emergence of latex protein allergyin the late 1980s and early 1990s reported to have affected 3 percent to 16percent of HCWs and about 1 percent of the general population1 has indeed caused much concern, says Esah Yip, PhD, director of the MalaysianRubber Export Promotion Council based in Washington, D.C.
Because latex protein allergy is brought about by the presence ofexcessive residual soluble proteins found in some latex gloves, a number ofnon-latex or synthetic alternatives have since become available in themarketplace, Yip says. These include those made of vinyl (PVC), nitrile,polychloroprene, and other materials. While these synthetic gloves may notcontain any plant proteins such as those found in natural rubber latex gloves,it is important for users to exercise caution when selecting gloves. They shouldbe made aware of the following information:
New technologies are now being used with natural rubber latex to reduce thepossibility of the development of allergic reactions to the latex. Manufacturers,using improved technologies, now can produce latex gloves with significantlyreduced amounts of residual soluble proteins. Todays latex gloves can haveprotein content as low as 50 micrograms/ square decimeter and below, compared tolevels that were sometimes more than 1,000 micrograms in the earlier generationof gloves. Clinical studies have indicated that gloves with such low proteinlevels have also low allergen content markedly reduced allergenicity, Yip explains.2
Research has shown that these upgrades can dramatically reduce the number of allergic or sensitivity reactions. Anumber of independent hospital studies recently in the United States, Canada,Germany,4 and Finland demonstrate that wearing low-protein, low- or non-powderedlatex gloves greatly diminishes the risk of allergic reactions and thelikelihood of healthcare workers developing latex sensitivity, she adds. Moreimportantly, the studies also show that latexallergic individuals wearingsynthetic gloves can work alongside their co-workers using low-protein latexgloves and suffer no ill effects.3-11
Low-protein latex gloves are clearly an appropriate choice for thenon-allergic majority. However, there is currently no glove regulatory requirement for protein andpowder, making it difficult for healthcare workers and clinicians to be certainthat the gloves they buy are indeed low-protein, Yip points out.
Malaysia, the major glove supplier to the United States, has recentlydeveloped the Standard Malaysian Glove (SMG) Program, which ensures themanufacture of quality low-protein gloves that are not only high in barrierprotection, but also low in allergy risk. The program was formulated in consultation with a number of relevantauthorities such the Food and Drug Administration. SMG-certified gloves have tomeet very stringent technical requirements, including strictly controlled lowlimits for residual extractable proteins and powder, she adds.
Diane Sosovec, RN, MS, CNAA, manager of clinical resources for CardinalHealth, was first hired to educate Cardinals customers about latexsensitivities and allergies. My focus was trying to help our customersunderstand what latex allergies and sensitivities were, vs. what they werent,she says.
Back then was when universal precautions and the Occupational Safety andHealth Administration (OSHA)s bloodborne pathogens standard hit the scene, and we hadall these HCWs who previously had not worn gloves, who were now expected to weargloves to comply with standards. All of a sudden we started to have HCWsreporting issues with their hands.
Unfortunately, most of the folks out there equated the reactions on theirhands to latex sensitivities and allergies, when in fact the overwhelmingreactions werent latex allergies, she explains. It was irritant contact dermatitis due to wearing gloves,washing their hands, not taking care of their hands appropriately, not usingmoisturizers and lotions, etc. At that time, many research articles beingpublished were talking about sensitization rates of HCWs, just throwing thesenumbers out there based on very limited studies. Also at that time, thehealthcare community was looking at these numbers, not understanding that latexsensitization didnt necessarily mean you had a latex allergy. The actualnumbers of sensitized individuals who had a true clinical allergic reaction to anatural rubber product was significantly smaller. Im not trying to minimizethis, because true latex allergy reactions can be very serious, evenlife-threatening, but its not any more or less serious than any other type ofprotein allergic reaction. I was focusing attention on what the real issues wereof HCWs: dry skin, irritant contact dermatitis, and non-latex alternatives forpeople who have issues with latex gloves.
For examination gloves, the alternatives are vinyl and nitrile. However,concern for the cost of synthetics may lead purchasers to choose a product thatis not always appropriate. In some healthcare facilities that have decided to go synthetic with theirexam gloves, because of the cost of the two products, theyre trying to getclinicians to use vinyl for the most part, when in fact, its not anappropriate barrier. You cant necessarily substitute vinyl for nitrilerubber, because it doesnt have the same barrier properties. Vinyl synthetic exam gloves are made of plasticizers, plastisols, which meansthey may fracture or tear more easily; they are not manufactured to the samestandard because its not the same material. Nitrile is the preferredsynthetic option in exam gloves because the material it is made out of is moredurable, it has more strength, and it is more resistant to chemicals, Sosovecpoints out.
Is it possible to use any low-protein rubber latex gloves for latex-allergicindividuals? If you have a true allergic reaction to natural rubber, nomatter what the natural rubber product is, even the lowest protein allergenproduct is still not safe for you, Sosovec says. Everyone has differences in their sensitization rate, their allergicreaction rate, so what may be safe for me if I have a mild sensitivity may notnecessarily be a safe option for someone with a severe allergic reaction. Theres only one safe option for a natural rubber latex allergic person,and that is no natural rubber.
She adds that when these issues surfaced more than a decade ago, many triedto make it a glove issue rather than remembering that latex appears inmany more products. There are 40,000 natural rubber latex products out there, she pointsout. Lets not forget condoms and diaphragms, which have been used fordecades by millions of people, and if all of a sudden there were these issueswith natural rubber latex allergies, I think we would have seen it before theglove issue.
With the influx of gloves, clinicians werent aware of the fact that itmade a difference how you wore the gloves, how long you wore them, and if youwere washing your hands before and after, if you were using lotions andmoisturizers. You had this group of HCWs who previously werent wearinggloves, who were now wearing 10, 20, 30, 40 pairs of gloves a day, on top ofwashing their hands before and after glove removal.
Quite frankly, who wouldnt have an irritation or a contact dermatitis withtheir hands? But back then, it wasnt understood as it is today. Also, back then, the examination gloves for the most part were powdered gloves, and thepowder could be a source of irritation.
As for surgical gloves, the preferred material is still natural rubber latex,due to its tactile sensitivity and manual dexterity. In the past, there wasthis belief that the more exposure there is, the higher the probability that youlldevelop a sensitization or allergy, Sosovec adds. When I lecture I may have an audience of 100 to 150people I ask them, How many of you eat fruits and vegetables?Everybody raises their hand. I ask all who raised their hands, How many ofyou have been eating them all your life? Everybody raises their hand. I ask,How many of you have an allergy to a fruit or vegetable? Usually, in an audience of 100 people, I might have one or two raise theirhand.
The protein allergens in fruits and vegetables arent any different fromthe protein allergens in natural rubber. If youre genetically predisposed, ifyou have a history of other allergies, if you are a clinically reactive person,thats what is going to put you at risk. Its not a cumulative effect. If itwere true, what about all of these millions of condoms and diaphragms that arebeing used? Some of these beliefs out there have really not been accurate. Theyve beenperceptions, not realities.
One of the other misconceptions is that HCWs because they had worn latexgloves for all these years were at higher risk for latex sensitization. Thatsbeen disproved as well, she says. The reports in early research were notnecessarily reporting results based on skin prick tests and serum tests. Theyhad been done based on simple surveys, reports, individual assessments notnecessarily made by an allergist. They were done based on seeing someoneshands, or anecdotal information. Ive never seen a study that actuallyquantifies true latex allergies. Sensitization rates, yes, but not true allergic reactions and allergies.
For surgical gloves, the most popular alternatives to latex are neoprene andsynthetic polyisoprene. From an end-user perspective, I would have to say thepreferred is the synthetic polyisoprene, because it has all of the attributesand physical characteristics and performance standards that natural rubber has,so its natural rubber without the protein allergens.
Little new research has been done recently into latex allergies, because manyof the earlier misconceptions have been cleared up. There isnt that much talk about it anymore; it has waned in its popularity because people have gotten their arms aroundit and they are dealing with it just like with any other allergy, Sosovecsays.
Of new interest to HCWs is guayule (pronounced why-YOU-lee), a desertplant that produces a different type of rubber, one that does not contain thetropical proteins found in rubber from Hevea brasiliensis, known as therubber tree.
Those proteins that are problematic in regular rubber latex are not therein the first place (in guayule), says Katrina Cornish, PhD, senior vicepresident of research and development for Yulex Corporation. Cornish, a formerUSDA research scientist, developed the guayule processing technology now beingcommercialized by Yulex.
Quite a large number of species make natural rubber, but apart from H.Brasiliensis, guayule is the only other one in commercial production. Theproteins in Hevea latex are all different from the proteins in guayulelatex, she explains. The plants are very distantly related; each of them is in adifferent superorder of the Dicotyledonous class. Those are broad-leaf floweringplants. Theyre about as distantly related as they can be and still be aflowering plant. Guayule is actually in the sunflower family.
Guayule is different from mostrubber-producing species in that it produces rubber in particles, which are tinyballs of rubber in the cytoplasm of cells in the bark. Other rubberproducingspecies produce it in latex vessels, pipelike tubes that run inside the bark ofplants. You can cut into those plants and the rubber would bleed out like amilky liquid. With guayule, theyre in individual cells, so if you cut into a guayuleplant, nothing happens. You dont see anything bleed out. However, you can grind up the plant and release all those rubber particlesinto the liquid and then purify them, and then you get, in effect, anartificially produced natural rubber latex emulsion that you can then use in thesame manufacturing processes you would use as any other latex for, she adds.
You get this very low-protein material, and none of those proteinscross-react with type 1 latex allergy. The low protein nature of the materialmeans its unlikely to cause an allergy in its turn, because its lower thanthe amount that well-leached Hevea products had for many decades whenthey werent causing a problem, and the fact that it doesnt cross-reactmeans it can safely be used by somebody whos got the allergy, much the sameway that the synthetics can be.
Unlike the synthetics, however, guayule actually has higher performanceproperties, because it does have the performance properties of natural rubbermaterials, Cornish explains.
Yulex worked in concert with several hospitals, including Johns Hopkins, tostudy the effect of guayule in latex-allergic individuals. Weve done studies with hundreds of type 1 latex allergic people,including testing their sera, but also some skin prick tests, and with adultHCWs, spine bifida children, and other people with latex allergies. Weve nothad any cases of cross-reaction with guayule latex materials.
The results of another clinical laboratory study using serum pools fromindividuals suffering from life-threatening type I tropical latex allergy indicate no detectable allergic reaction to commercial grade natural rubberlatex derived from guayule.
Immunologist Robert G. Hamilton, PhD, professor of medicine and pathology atJohns Hopkins University School of Medicine in Baltimore, presented the resultsduring the 2005 annual meeting of the American Academy of Allergy, Asthma andImmunology in San Antonio, Texas.
These results indicate that proteins present in production lots of guayulelatex are not cross-reactive with Hevea brasiliensis latex allergens.This suggests that devices manufactured with guayule latex as an alternativerubber source should be safe for use by H. brasiliensis latex-allergic individuals, reported Hamilton at theconference.
The study determined the level of allergenic protein with the CAP inhibitionassay. Researchers used serum containing IgE antibodies from two groups ofindividuals allergic to products made of tropical latex from the tropical rubbertree, H. brasiliensis. The guayule materials showed the same negativeresults as the neoprene synthetic latex material control group. However, the Hevea-basedgloves showed significant levels of allergenic protein.
New Alternatives to Old Standards
Ansell Healthcare Products has a continually expanding collection of bothlatex and latexfree examination gloves. The Micro-TouchÂ® Nitrile E.P.Â® is a textured, all nitrile, powder-free examination glove. Theglove is FDA-approved for handling chemotherapy drugs and provides excellentchemical and puncture resistance, and offers an extended cuff for extraprotection over the wrist and arm.
Ansell also offers the AffinityÂ®, a textured, latex-free (polychloroprene),powder-free examination glove that is designed toprovide the fit and feel of latex. There is the EliteÂ®, a soft-stretch,latex-free (polyvinyl chloride), powder-free examination glove for low-riskapplications. There is the ErgoGrip, a handspecific latex, powder-freeexamination glove with polymer coating for ease of donning. The NextStepÂ® is a textured latex, powderfree examination glove withglycerol that is designed to provide superior tactile sensitivity, fit, and comfort. And the Micro-TouchÂ® Plus is another textured, latex, powder-free examination glove with polymercoating for ease of donning.
Regent Medical offers a deproteinised natural rubber latex surgical glove.The latex, powder-free Biogel Eclipse is made from highly-refineddeproteinised natural rubber latex. Deproteinised natural rubber latex is thefinished product of a patented process that reduces extractable latex proteinsin the raw material by 90 percent.12 According to the Leap Testing Service atthe Guthrie Foundation for Education and Research, the levels of extractablelatex protein are below detection levels in the finished gloves.13 The new glovecategory also represents a costeffective safety option for facilities wanting toreduce exposure of healthcare workers and patients to antigenic proteins foundin standard latex surgical gloves without having to incur the higher cost ofnon-latex gloves for those not sensitized to latex proteins.
The Science Behind Improvements
In 2004, a review of natural rubber latex allergy in healthcare workers wasdone by Peter M. Ranta, MD, and Dennis R. Ownby, MD of the departments ofpediatrics and internal medicine in the section of allergyimmunology at theMedical College of Georgia in Augusta.14
The use of latex, they point out, has been documented back to 1600 B.C.However, it was not until 1979 that the first clear description ofimmediate-type hypersensitivity a type 1 allergy was published. A plague of latex allergies increased and then peaked in the mid-1990s, but theirincidence has decreased ever since. The authors attribute this decrease toadoption of low-allergen, powder-free latex gloves.
Latex gloves are associated with three types of adverse reactions:irritant contact dermatitis, immediate-type (type 1) allergic reactions, andallergic contact dermatitis (type IV or delayed-type hypersensitivityreactions), the authors write. Type 1 reactions are the only responses that can begeneral rather than local responses.
Reported occurrence of type 1 sensitivity has ranged from 2.9 percent to 12.1percent, the authors add. However, they note, latexallergic healthcareworkers who carefully avoid latex exposure have been observed to gradually losetheir sensitivity. But there is still a risk of re-sensitization if they arere-exposed to latex.
Once a healthcare worker develops an allergy to latex, the costs attributedto the disability can be enormous. The authors reference another study thatattests to these increased expenses, saying, Tyler reports that the averagecost of lost work time due to disability from latex allergy was $38,077 per casein 1996 in a Michigan healthcare organization; during the same year, the average cost of non-lost time associated with latexallergy was $219 per case. They define non-lost work time as medicalexpenses paid.
They then question the cost efficacy of switching to latex-free gloves. Phillipset al did a cost analysis in Georgia in 1999 of three types of medical caresettings: a tertiary care hospital, a community hospital, and a large internalmedicine clinic. According to their estimates, the annual cost of switching tolatex-free gloves was $515,789, $117,468, and $48 per facility, respectively ...if greater than 1 percent of workers become fully disabled, or if greater than 2 percent becomepartially disabled, these authors conclude that it would be cost-effective for atertiary-care facility to switch to latex-free gloves.
However, a complete switch to latex-free is not always necessary; The MayoClinic reported a cost saving of $200,000 per year with a switch tolow-allergen, powder-free latex gloves; similarly, a Canadian teaching hospitalin Ontario reported no increase in cost with this approach as a result ofconsolidated glove purchases, they add.
Reduction of exposure to latex is a safe and more economical alternativeto complete removal from the place of employment, they conclude.
Travis W. Honeycutt, the founder and chairman of Vystar Corporation,presented a paper at the Latex 2006 conference in Frankfurt, Germany, describingthe technological and physical properties of a new, low-antigenic protein natural rubber latex.15
The paper describes a unique method of lessening the impact of normal levelsof antigenic proteins, while not negatively impacting the necessary chemical andphysical properties of the latex.
Vystar Corporation has developed a novel, patented method for thedeactivation of the antigenic protein (AP) in liquid natural rubber latex (NRL)that involves the denaturing of these proteins. This new, patented method forfixing the protein problem results in equal or slightly improved chemical andphysician properties in NRL, thus allowing a seamless transition formanufacturers using the current commercially available product. Of particularinterest is that the low-antigenic NRL appears to have a slightly reducedinitial modulus when compared to untreated NRL. A reduced initial modulustranslates into greatly reduced fatigue for items such as surgeons gloves orexamination gloves that are worn for a considerable period of time, theauthors write.
The method involves treating the NRL in the liquid phase with selectedinorganic chemicals, which include AI(OH)3 and SiO2 as alkali solutions, beforevulcanization. The resultant product has been trademarked as Vytex by Vystar.
Glove leakage tests performed on Vytex revealed that gloves made withanti-protein additives had better liquid barrier protection as compared tountreated latex gloves. Of note, a defined concentration of anti-proteinadditives is necessary to maintain the desirable physical properties of productsmade from natural rubber latex. Some parameters, such as tensile strength,ultimate elongation, and resistance against aging are increased when the amountof anti-protein additives in NRL was increased within a certain range, theauthors write. Exceeding the desired concentration amount will result in adeterioration of the mechanical properties of latex products.
The addition of alkali solution of aluminum hydroxide or silicon oxide toliquid latex allows the production of high-quality products from newlow-protein latex without changing existing technology, the authors conclude.Antiprotein additives increase the elasticity and strength of the latex filmsif concentrations of these additives are not exceeded. Removal of the antigenicprotein occurs at sub-critical concentrations of anti-protein additives. Simultaneously, the barrier properties and resistance against aging of latexproducts with these additives are not only maintained, but also essentially improved.
1. Based on ASTM D6499-03Inhibition ELISA Assay. Testing conducted at Guthrie Foundation for Educationand Research, LEAP Testing Service, February 2005. Detection limit 0.2Ãg/g.
3. Liss GM, Sussman GL. Latex Sensitization: Occupational versus generalpopulation prevalence rates. Am. J. Ind. Med 1999; 35: 196-200.
4. Yip E, Cacioli P. The manufacture of gloves from natural rubber latex. JAllergy Clin Immunol. 2002; 110: S3-14.
5. Tarlo SM et. al. University of Toronto, J Allergy Clin Immunol. 2001;108: 628.633;
6. Rueff F. et. al. Dermatologie & Allergologie, University of Ludwig-Maximillians, Munich, Germany, AAAAI meeting, 2000;
7. Hunt, LW. et. al. Mayo Clinic, J Allergy Clin Immunol. 2002; 110:S94-106;
8. Allmers H. et. al. Germany, J Allergy Clin Immunol. 2002;110(2):318-323;
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11. Kelly KJ, et. al. Wisconsin, U.S.A. J Allergy Clin Immunol. 2003;3(2), #2, #426.
12. Allmers H. et. al. AAAAI meeting 2004, Abstract # 138;
13. Renuala T. et. al. AAAAI meeting 2004, Abstract # 140.
14. Ranta PM and Ownby DR. A Review of Natural-Rubber Latex Allergy in HealthCare Workers. Clin Infect Diseases 2004;38:252-6.
15. Honeycutt T, et al. Technological and Physical Properties of a New, LowAntigenic Protein Natural Rubber Latex. Latex 2006; January 24-25, 2006. Frankfurt, Germany.