A New Generation of Latex Gloves Greatly Reduces Protein Allergy Risk
By Esah S. Yip, DSc
Disposable medical gloves are often a healthcare worker (HCW)s only barrier against blood and other fluids that can spread infectious diseases such as AIDS and hepatitis B. That makes selecting the right gloves a critical decision.
Natural rubber latex gloves have long been considered the gold standard for barrier protection, comfort, fit and cost, but concern for colleagues and patients who are sensitive to latex protein can pose a dilemma for medical and healthcare facilities. Some healthcare institutions have responded by turning to facility-wide use of synthetic alternatives, even though some commonly used synthetics have inferior barrier protection and other properties.
However, new research shows that a better option is to use latex gloves with reduced protein and powder levels, which allows healthcare facilities to offer the highest quality barrier protection with a reduced risk of latex allergy at no additional cost.
Ensuring Barrier Protection
While specific tasks and procedures should dictate the type of glove that is used, the single most important criterion in glove selection is barrier protection against the spread of infection. Scientists have studied extensively the barrier protection qualities of some most commonly used gloveslatex, vinyl, nitrile and polychloroprene (see Table 1). Latex gloves have consistently demonstrated high levels of barrier protection, particularly when compared to vinyl. Although nitrile and polychloroprene gloves also provide high-quality barrier performance comparable to latex gloves, only latex combines that with the other important in-use characteristics of good fit, comfort, elasticity, tactile sensitivity, high tear resistance and ease of donning.
In addition, the natural rubber polymer gives latex gloves a unique resealing capability that makes them much less susceptible to viral penetration through tiny needle punctures. Synthetic gloves, such as vinyl or nitrile, tend to tear easily once punctured and do not reseal. 9-10
Latex Gloves and Protein
Latex gloves are made from the milky fluid from the trees of Hevea brasiliensis. Hevea latex is a plant material that contains rubber (about 30 percent, in the form of particles), as well as non-rubber substances such as carbohydrates, proteins and some minerals. Total proteins constitute about 1 percent of latex. When the latex is processed into gloves, many of the soluble proteins are lost, often leaving behind only a small amount of residual extractable protein. Not all of these residual extractable proteins cause allergic reactions.
Because they are water soluble, many of these remaining proteins 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 that were in use at the dawn of the AIDS epidemic, when the demand for latex gloves spiked 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 of residual extractable protein per gram of glove high enough to cause sensitization and trigger allergic reactions in latex-sensitive individuals. However, the current generation of latex gloves can have levels as low as 50 micrograms, and less, especially for powder free latex gloves (as estimated by the Modified Lowry Test).
Table 2, which compares five brands of latex gloves,13 demonstrates that powdered latex gloves produced using the older manufacturing technology contain significantly higher protein content 4-5 than the low-protein gloves manufactured by the improved processes. 1-3
Latex Gloves and Powder
Cornstarch powder is used in the manufacture of latex gloves to prevent the sides from sticking together and to facilitate donning. The powder has been shown to absorb extractable proteins from gloves during processing. When dry, the powder particles can become airborne, carrying latex proteins with them. Inhalation of these aeroallergens is thought to cause sensitization among some individuals, as well as to elicit allergic reactions in those who are already sensitized. Many reports of latex protein allergy have been associated with the use of heavily powdered gloves with high residual extractable protein content.
Advancement in manufacturing technologies has today led to the reduction of not only the residual extractable protein content of gloves, but also to a decrease in their aeroallergenicity.
Low Protein/ Low Powder Latex Gloves
Research has shown the reduction of residual extractable protein 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-powdered latex gloves greatly diminishes the risk of allergic reactions and the likelihood of HCWs developing latex sensitivity. In addition, studies have shown that the use of low-protein, low-powder or non-powdered gloves allowed latex-sensitive individuals donning synthetic gloves to work safely alongside colleagues wearing low-protein latex gloves. One of the studies found that even latex-allergic individuals could use natural rubber latex gloves with very low allergenic protein content, although it is generally recommended that such individuals continue to wear synthetic substitutes.
The National Institute for Occupational Safety and Health (NIOSH) now recommends using non-powdered latex gloves that have low protein content.21 The Academy of Medical Surgical Nurses suggests the use of powder-free latex gloves with reduced protein content for handling infectious materials,22 and the American Nurses Association recommends powder-free (< 2 mg particulate weight per glove) gloves with low protein content (consistently below 50 µg/g).23
Identifying Low-Protein/Low-Powder Gloves
To help consumers identify low-protein, low-powder or powder-free, high-quality latex gloves, Malaysia, a supplier of medical gloves (latex and synthetic) to the United States, has formulated the Standard Malaysian Glove (SMG) program in consultation with the Food and Drug Administration (FDA). It ensures the manufacture of high-quality low-protein latex gloves with high barrier performance and low allergy risk. Latex gloves bearing the SMG seal must meet stringent barrier and tensile specifications as well as rigorous standards for protein and powder content, which are in line with the American Society for Testing and Materials (ASTM). These gloves are now available in powder-free and lightly powder varieties.
ECRI, a non-profit health research company, and the worlds largest independent evaluator of biomedical equipment, also recommends the use of low-protein latex gloves that have protein levels printed on their labeling, or that bear the SMG seal, particularly the powder-free variety, because these gloves are guaranteed to have low protein and powder limits.24
The advent of low-protein gloves like SMG allows the majority of HCWs who are not latex-sensitive to continue using latex gloves, and to take advantage of their barrier performance properties without endangering latex sensitive co-workers. The use of these gloves, especially the powder-free variety, can also serve to vastly reduce the risk of developing sensitivity to latex.
As a matter of precaution, latex-sensitive individuals should avoid using latex gloves and select non-latex or synthetic gloves that provide adequate barrier protection.