Update:The American Society of Testing and Materials (ASTM), a non-governmental, not for profit agency, develops voluntary glov...
The American Society of Testing and Materials (ASTM), a non-governmental, not for profit agency, develops voluntary glove standards. Members of ASTM medical glove working groups include representatives from glove manufacturers, testing laboratories, government agencies and healthcare.
The physical performance standards they develop establish minimum acceptable strength, elongation, thickness, dimension and modulus requirements for natural rubber latex (NRL) and synthetic gloves. Test methodologies including viral penetration and chemical permeation have been developed to further characterize barrier performance; however, manufacturers are not required to perform these specific evaluations.
Relevant Test Methods
Some of the more relevant test methods include,
but are not limited to:
Water leak (ASTM D5151): This test is performed by placing an unused glove over the end of a vertical cylinder and filling it with 1,000 milliliters of water. After a two-minute period, the glove is observed for leaks.20 Values are stated as Acceptable Quality Levels (AQL), which is roughly the percent failure rate allowed.
Relevance: Holes, rips and/or very weak areas that rupture in the leak test indicate that barrier
protection is compromised.
Thickness (ASTM D3767): The thickness of a single layer of glove is measured in millimeters (mm) utilizing a micrometer at specified locations on the upper finger, palm and cuff.21
Relevance: Thickness is an important component of barrier protection consistency for both durability and chemical permeation.
Strength or Tensile Strength (ASTM D412): Strength is measured in megaPascals (MPa) to assess the amount of force applied to a glove until it breaks. The calculation is adjusted to
normalize for thickness.
Relevance: The lower the tensile strength, the more easily materials of the same thickness can break when snagged or pressure is applied. For example, fingernails exert a tremendous amount of concentrated pressure at glove fingertips.
Ultimate Elongation (ASTM D412): The ability to stretch is determined by extending a strip of glove until it breaks. The percentage the strip is stretched until the break is the ultimate elongation.
Relevance: This stretchability is very important at the microscopic level where the glove material must be able to give rather than break when stressed or snagged by instruments, fingernails, ridges on caps, twisting stop cocks on IV sets, snapping off enclosures or any tasks performed with gloved hands.
Modulus, resistance to movement or stress at 500% elongation (ASTM D412): This is determined by the amount of force (effort) required to stretch the glove. The lower the modulus, the less effort required for movement.
Relevance: This measurement enables one to predict the effort wearers will have to exert to perform tasks. This has an indirect impact on barrier performance as hand fatigue may lead to accidents (e.g., puncture, tearing and/or ripping glove material) during procedures.
Since the physical properties of synthetic materials differ from each other and from NRL, one standard cannot be applied to all gloves. Tables 2 and 3 specify the minimally acceptable ASTM physical performance standards of unused gloves made of different materials. It is important to emphasize that these are minimal standards. Manufacturers vary in the rigorousness of their internal requirements. For instance, some manufacturers have standards that are more stringent than those of ASTM requirements (e.g., an AQL of 1.5 instead of the more lenient 2.5 for exam glove leaks).
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