A New Generation of Latex Gloves

Most proteins that can trigger latex allergies can be removed.

More than 40,000 types of commercial products are made from natural rubber latex (NRL), an extract of the Pará rubber tree. Valued for its desirable properties, NRL is used in numerous products in the medical industry and elsewhere, including latex gloves. However, out of more than 200 proteins contained within NRL, 13 are known to be allergens. The American Latex Allergy Association estimates that up to 1 percent of the general population and 17 percent of health care workers exhibit some form of latex allergy, thus hindering their use of gloves made from this material.

Fortunately, a solution to the protein content of NRL exists. It involves the patent-protected addition of aluminum hydroxide, Al(OH)₃, a well-known protein binding chemical, to latex while still in liquid form. This compound acts as a binding agent to the latex and produces protein complexes that can be removed using existing industry practices. The result is an ultra low-protein variant of NRL that retains the advantages of latex with most of the antigenic proteins removed. How is this patented aluminum hydroxide-modified NRL made, what advantages does it offer health care workers and others who wear latex gloves, and what makes it superior to standard NRL?

The treatment process for this type of modified NRL removes specific non-rubber impurities from NRL through the directed application of aluminum hydroxide. A commonly used absorbent, emulsifier, ion-exchanger, and antacid, aluminum hydroxide is commonly used in the process of water purification. It forms a jelly-like structure suspending unwanted materials in water, including bacteria.

Using traditional latex processing methods, a slurry of aluminum hydroxide can be strategically added to the harvested latex. The effective binding of protein and other non-rubber impurities from this latex emulsion to insoluble aluminum hydroxide occurs, with some of the non-rubber impurities adsorbed to the reactive surface of the aluminum hydroxide crystals.

With this patented processing step integrated into the manufacturing stage, there is no added expense of capital equipment. Reacted aluminum hydroxide complexes are removed by standard filtration and centrifugation. The remaining rubber particles retain the surrounding lipid layer, which, during subsequent maturation, improves the mechanical stability of the latex. Scientists have observed that this process yields products that exhibit greater clarity and significantly reduced odor, in addition to the removal of most of the antigenic proteins, without sacrificing the properties that give NRL advantages over synthetic alternatives. Prior industry efforts have produced reduced protein-source latex through the treatment of raw latex with enzymes, with little commercial success.

A New Latex Glove
The rise of the AIDS epidemic in the 1980s highlighted the widespread use of latex gloves to protect against infection. But for many health care professionals, the increased exposure to latex led to allergic reactions. Symptoms ranged from watery and itchy eyes to red and irritated skin, to breathing trouble and even life-threatening anaphylaxis. Some health care professionals developed dangerous latex allergies that, in some cases, limited or ended their care-providing careers. Latex gloves were also negatively perceived because of the powder associated with the gloves that left residue on users' hands and caused skin irritation.

It must be stressed that NRL gloves are known for their superior barrier properties and cost effectiveness. As such, they have been, and still are, widely used, particularly in health care settings where effective barrier protection is of great importance against viral transmission and infectious diseases. With the exception of vinyl or PVC gloves, which have been shown to provide lesser barrier protection, latex gloves are generally less expensive than many synthetic alternatives, such as polyisoprene, neoprene, and often nitrile.

There is thus an obvious market for this aluminum hydroxide-modified NRL in the surgical, examination, and industrial glove markets. Both surgical and examination gloves in manufacturer trials contained significantly fewer antigenic proteins than untreated control gloves. This indicates that glove manufacturers using the aluminum hydroxide-modified NRL as their raw material can adhere to ASTM glove protein compliance levels with only "pre-leaching" to remove residual compounding chemicals, thus conserving water and energy. While reducing the antigenic protein content, such gloves preserve the durability, comfort, fit, tactile sensitivity, and high resistance to puncture and tear for which NRL is known.

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Source: Occupational Health & Safety