Unigloves & Protein Control

Q1 What are the proteins present in latex gloves?

Proteins are naturally present in natural rubber latex extracted from the Hevea Brasiliensis tress. Among those proteins are enzymes involved in the biosynthesis of the rubber itself, while other proteins are important for maintaining the colloidal stability of the latex.

The total protein content of the latex is approximately 1-5% of the total weight. These proteins that originated from the latex are water-soluble and hence can be removed through proper leaching of the products.

Q2 What is the acceptable protein limit in latex gloves?

• No legal maximum for leachable proteins in European Standard.

• ASTM sets the upper limit of residual extractable protein at 200ug/dm2 (as measured by modified Lowry method) and allergenic proteins 10ug/dm2 (measured by ELISA method).

• The Standard Malaysian Glove scheme sets the upper limit of 200ug/dm2 for powdered gloves and 50ug/dm2 for powder free gloves.

• 50ug of water-extractable protein per gram of glove is the lowest limit of sensitivity of the modified Lowry test method, recognized by the FDA.

Q3 Is low protein level ensure low protein allergic reaction?

The threshold level for protein sensitization is not known, but study shows that the lower the extractable protein content present in gloves, the lower the allergic responses demonstrated by the latex sensitized individuals when clinically skin tested. This is further supported by the study that the modified Lowry method which determine the total extractable protein concentration correlate relatively well with the true allergen content, measured by skin prick testing or latex-specific human IgE-based methods.

Hence it could be said that the lower the extractable protein content in glove, the lower the allergen in glove that could possible activate the allergic reactions in sensitized person.

Q4 What are the standard test methods for extractable proteins?

• The ASTM D5712-95 Standard Test Method – The modified Lowry assay test method which proteins are extracted in distilled water and concentration determined against ovalbumin protein standards. The test results are expressed in ug/g, and its sensitivity limit is less than or equal to 50ug/g. However certain additives or surfactants can cause false high value fue to interference.

• The ASTM D5712-99 Standard Test Method – A revised modified Lowry assay test method which proteins are extracted in phosphate buffered saline solution. The test results are expressed in ug/dm2, and its sensitivity limit is less than or equal to 50ug/g.

• The European Standard Test Method, EN455:3:2000 – Modified Lowry Assay method which proteins are extracted by an extraction buffer, N-tris(hydroxymethyl)-methyl-2-aminomethane-sulphonic acid, also known as TES, and concentration determined against ovalbumin standards.

• The ELISA ASTM D6499-00 Standard Test Method – An ELISA-based protein test method that detects allergenic proteins.

Q5 How Unigloves ensure low protein content gloves?

Technical Aspects

• Unigloves monitor consistently the protein level at manufacturing processes for powdered gloves and up to the powder free treatment processes for powder free gloves.

• The manufacturing machines of Unigloves are designed to remove the extractable proteins through few leaching processes, with temperature enhancing and at the same time maintain the manufactured gloves’ strength and quality.

• The powder free processes are incorporated with sufficient washing cycles with continuous running of fresh water to remove the residual proteins to ensure the protein level of the powder free gloves are at the lowest level.

Testing & Verification

• Unigloves test in-housely both powdered and powder free gloves monthly in accordance to ASTM Standard Test Methods to ensure our gloves is in compliance to the acceptable limits.

• Unigloves confirm the compliance of the protein level of the gloves manufactured by sending the gloves for accredited independent laboratory’s verification quarterly.

Research & Development

• R&D activities are carried out actively at Unigloves to search for more advance and efficient protein reduction technologies, and yet maintain the high barrier quality of gloves.

• Example of on hand R&D activities are polymer coating and enzymatic deproteinization techniques which favorable results are shown in numerous studies or researches published.