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A New Generation of Latex Gloves Greatly Reduces Protein Allergy Risk
By Esah S. Yip, DSc
Disposable medical gloves are often ahealthcare worker (HCW)s only barrier against blood and other fluids thatcan spread infectious diseases such as AIDS and hepatitis B. That makesselecting the right gloves a critical decision.
Natural rubber latex gloves have long been considered the goldstandard for barrier protection, comfort, fit and cost, but concern forcolleagues and patients who are sensitive to latex protein can pose a dilemmafor medical and healthcare facilities. Some healthcare institutions haveresponded by turning to facility-wide use of synthetic alternatives, even thoughsome commonly used synthetics have inferior barrier protection and otherproperties.
However, new research shows that a better option is to uselatex gloves with reduced protein and powder levels, which allows healthcarefacilities to offer the highest quality barrier protection with a reduced riskof latex allergy at no additional cost.
While specific tasks and procedures should dictate the typeof glove that is used, the single most important criterion in glove selection isbarrier protection against the spread of infection. Scientists have studiedextensively the barrier protection qualities of some most commonly used gloveslatex,vinyl, nitrile and polychloroprene (see Table 1). Latex gloves have consistently demonstrated high levels ofbarrier protection, particularly when compared to vinyl. Although nitrile andpolychloroprene gloves also provide high-quality barrier performance comparableto latex gloves, only latex combines that with the other important in-usecharacteristics of good fit, comfort, elasticity, tactile sensitivity, hightear resistance and ease of donning.
In addition, the natural rubber polymer gives latex gloves aunique resealing capability that makes them much less susceptible to viralpenetration through tiny needle punctures. Synthetic gloves, such as vinyl or nitrile, tend to tear easily once punctured and do notreseal. 9-10
Latex gloves are made from the milky fluid from the trees ofHevea brasiliensis. Hevea latex is a plant material that contains rubber (about30 percent, in the form of particles), as well as non-rubber substances such ascarbohydrates, proteins and some minerals. Total proteins constitute about 1percent of latex. When the latex is processed into gloves, many of the solubleproteins are lost, often leaving behind only a small amount of residualextractable protein. Not all of these residual extractable proteins causeallergic reactions.
Because they are water soluble, many of these remainingproteins can be removed from latex gloves by proper processing, particularly by the application of a pre- and post- leaching protocol.12
These manufacturing techniques are far superior to those thatwere in use at the dawn of the AIDS epidemic, when the demand for latex glovesspiked and hurriedly manufactured gloves with high levels of protein began to flood the market. Those gloves contained as much as 1,000 to 2,000 micrograms ofresidual extractable protein per gram of glove high enough to causesensitization and trigger allergic reactions in latex-sensitive individuals.However, the current generation of latex gloves can have levels as low as 50micrograms, and less, especially for powder free latex gloves (as estimated bythe Modified Lowry Test).
Table 2, which compares five brands of latex gloves,13demonstrates that powdered latex gloves produced using the older manufacturingtechnology contain significantly higher protein content 4-5 than the low-protein gloves manufactured by the improved processes.1-3
Cornstarch powder is used in the manufacture of latex glovesto prevent the sides from sticking together and to facilitate donning. Thepowder has been shown to absorb extractable proteins from gloves duringprocessing. When dry, the powder particles can become airborne, carrying latexproteins with them. Inhalation of these aeroallergens is thought to causesensitization among some individuals, as well as to elicit allergic reactions inthose who are already sensitized. Many reports of latex protein allergy havebeen associated with the use of heavily powdered gloves with high residualextractable protein content.
Advancement in manufacturing technologies has today led to thereduction of not only the residual extractable protein content of gloves, butalso to a decrease in their aeroallergenicity.
Research has shown the reduction of residual extractableprotein to have a significant impact on reducing the incidence of allergic reactions to latex. Recent hospital studies14-20 in the U.S.,Canada and Europe demonstrate that wearing low-protein, low-or non-powderedlatexgloves greatly diminishes the risk of allergic reactions and thelikelihood of HCWs developing latex sensitivity. In addition, studies have shownthat the use of low-protein, low-powder or non-powdered gloves allowedlatex-sensitive individuals donning synthetic gloves to work safely alongsidecolleagues wearing low-protein latex gloves. One of the studies found that evenlatex-allergic individuals could use natural rubber latex gloves with very lowallergenic protein content, although it is generally recommended that suchindividuals continue to wear synthetic substitutes.
The National Institute for Occupational Safety and Health(NIOSH) now recommends using non-powdered latex gloves that have low proteincontent.21 The Academy of Medical Surgical Nurses suggests the use ofpowder-free latex gloves with reduced protein content for handling infectiousmaterials,22 and the American Nurses Association recommends powder-free(< 2 mg particulate weight per glove) gloves with low protein content (consistently below 50Âµg/g).23
To help consumers identify low-protein, low-powder orpowder-free, high-quality latex gloves, Malaysia, a supplier of medical gloves(latex and synthetic) to the United States, has formulated the StandardMalaysian Glove (SMG) program in consultation with the Food and DrugAdministration (FDA). It ensures the manufacture of high-quality low-proteinlatex gloves with high barrier performance and low allergy risk. Latex glovesbearing the SMG seal must meet stringent barrier and tensile specifications aswell as rigorous standards for protein and powder content, which are in linewith the American Society for Testing and Materials (ASTM). These gloves are nowavailable in powder-free and lightly powder varieties.
ECRI, a non-profit health research company, and the worldslargest independent evaluator of biomedical equipment, also recommends the useof low-protein latex gloves that have protein levels printed on their labeling,or that bear the SMG seal, particularly the powder-free variety, because thesegloves are guaranteed to have low protein and powder limits.24
The advent of low-protein gloves like SMG allows the majorityof HCWs who are not latex-sensitive to continue using latex gloves, and to takeadvantage of their barrier performance properties without endangering latexsensitive co-workers. The use of these gloves, especially the powder-freevariety, can also serve to vastly reduce the risk of developing sensitivity tolatex.
As a matter of precaution, latex-sensitive individuals shouldavoid using latex gloves and select non-latex or synthetic gloves that provideadequate barrier protection.