Hand in glove – are you doing it right?

With so many different gloves available for the laboratory market, how do you know which one would best suit your needs? Jaime Cassar and Roberto Greselin give us their guide to choosing the right glove

The selection of gloves for use in the laboratory is becoming increasingly important. There is a growing understanding among laboratory managers, laboratory personnel and health and safety managers of the different ways gloves can impact laboratory activity. Requirements for demonstrating compliance with both Health & Safety Legislation and Good Laboratory Practices (GLPs) also result in more stringent justification of the laboratory glove selection.

This has created a shift in the way people view laboratory gloves, from what were traditionally seen as a “laboratory commodity products” to what are now viewed by many as “tools used to perform the science safely and effectively”.

The key considerations of laboratory gloves selection can be categorised into three groups of requirements, which reflect the different ways in which gloves can impact laboratory activity: i) health and safety requirements, ii) application specific requirements, and iii) user specific requirements. A successful laboratory glove selection process will address all three groups of requirements.

Health & safety requirements

A glove for use in the laboratory should be certified in accordance with the EU Directive 89/686/EEC, as a PPE Category III product (for use where effects are irreversible or mortal risk is present). The packaging should show a CE mark followed by four digits which identify the notified body that approved its PPE Category III certification.  Packaging should also show pictograms for compliance with the following standards: EN374-1 protection from chemicals (low risk), EN374-2 protection from microorganisms, EN420 general requirements for protective gloves.

Gloves certified as a medical device according to Directive 93/42/EEC (for use in protecting the patient from infection) should not be used in a laboratory unless PPE Category III certification is also present on the packaging.

To comply with health and safety legislation, laboratories must assess the type and level of risk personnel may be exposed to, and according to this select a glove with the appropriate level of certification and performance with respect to test standards relevant to the risk.

Chemical splash hazards:

A chemical splash may permeate through the glove and cause harm to the user. Assess the level of risk by referring to the chemical’s hazard classification and evaluating the likely exposure time to that chemical for the particular application. Select a glove where the published EN374-3:2003 test data shows a breakthrough time for the particular chemical and concentration that is greater than the likely exposure time.

When the risk involves cytotoxic drugs, further test data such as ASTM 6978-05 (Standard Practice for Assessment of Resistance of Medical Gloves to Permeation by Chemotherapy Drugs) may be available, to demonstrate a glove’s appropriateness for use with chemotherapy drugs.

Microorganism hazards:

A microorganism may penetrate through a microscopic hole in the glove and cause harm to the user. Test standard EN374-2:2003 protection from microorganisms requires glove manufacturers to measure the Acceptable Quality Level (AQL) for pinhole defects using the air or water tightness test. As per ISO 2859, a lower AQL means a lower tolerance to defects in order to release the production lot. When dealing with viruses, consider a glove with EN374-2 Level 3 designation, signifying an AQL of 0.65.  EN374-2 Level 2 designation signifies an AQL of 1.5, more appropriate for protection against penetration by bacteria or fungi.

In the case of viruses, further test data such as ISO 16604:2004 and ASTM F1671-97b (Standard Test Method for Resistance of Materials Used in Protective Clothing to Penetration by Blood-borne Pathogens using Phi-X174 Bacteriophage Penetration as a Test System) may be available, to demonstrate a glove’s appropriateness for use with viruses.  Double donning gloves is an added precaution that can be used to mitigate penetration risks from viruses.

When selecting a glove, take into consideration that gloves made from the same material will not necessarily provide the same level of protection. Though Nitrile gloves typically provide more barrier protection to chemical permeation than Latex gloves, not all Nitrile gloves are the same. The thickness, density, elasticity and quality of the Nitrile material can affect the glove’s chemical splash and micro-organism protection properties. These attributes can be modified in the formulation and manufacturing process, which can differ across different brands of gloves. One must refer to the test data and certification for the specific glove being considered, and not simply rely on its material type to make a choice.

Application specific requirements

Different applications give rise to different needs for protection and functionality, which must be addressed in the glove selection process. The need for protection goes beyond health and safety, and considers protection from contamination.

A glove manufactured with low standards of cleanliness may contain surface residues that are a potential source of contamination. For example, the outcome of Electrophoresis and Polymerised Chain Reaction can be distorted by the presence of protein contamination. Though Latex gloves are typically associated with protein contamination, any glove with noticeable surface residue or a strong odour can be a potential source of protein, particulate and chemical contamination. Surface residue can be detected by simply rubbing the surface of a glove between two fingers and then rubbing those two fingers together. Mitigation of such contamination risks can be achieved by avoiding the use of Latex gloves and selecting a glove with no noticeable surface residue or odour.

The need for functionality considers the physical attributes of the glove that allow it to be used to perform procedures safely and effectively.  Here are examples of how these physical attributes can impact functionality:

• Dexterity and tactile sensitivity are required in procedures that involve high levels of precision and control to perform effectively, and will also help protect sensitive instruments from damage caused by improper handling.
• Grip is required when handling delicate pieces of equipment such as glass apparatus or precision instruments. When selecting a glove, try the glove on and test if the level of grip is acceptable for the specific activity. The grip of a glove is dependent on its surface finish and texture, which are controlled in the manufacturing process.
• Comfort is a key requirement for many applications in the laboratory. Gloves that are not comfortable may increase hand strain which can lead to accidents, impacting the procedure and user health and safety.
• Longer length gloves are required when the application presents a risk of chemical splashes to the wrist area. PPE Legislation for gloves (standard EN420) specifies the minimum length of gloves to be between 24cm-25cm (depending on the size). Some gloves are also available with a 30cm length, providing an extended cuff to give more complete protection to the wrist.
• Tear resistance and thickness are required in tasks that put more physical stress on the gloves. A glove that tears in use can be both a health and safety and contamination risk. Test standard EN455-2 measures the tensile strength and ultimate elongation of a glove.

Innovations in Nitrile technology are helping to deliver the high levels of comfort, dexterity and tactile sensitivity, typically associated with Latex, without compromising the barrier protection of Nitrile. Because the cleanliness and physical attributes of gloves can be manipulated in the formulation and manufacturing process, one must assess a glove’s performance with respect to contamination and functionality, and not simply rely on its material type to make a choice.

User specific requirements

Every person is different. This creates user specific requirements for gloves which must be addressed in the selection process. People have different sized hands, some may be allergic to specific substances and some people may have more sensitive skin than others.

Gloves need to fit properly to fulfil the health and safety and application specific requirements for which they were selected. Glove manufacturers use a common sizing system dictated by EN420, which regulates the minimum length of a glove. Despite this standard, the best way to determine if a glove fits properly is to try it on. The proportions of finger length and palm length of a person’s hands can differ by individual. There can also be variations in the dimensions and proportions of gloves from different manufacturers.

Gloves containing natural rubber Latex may induce an allergic reaction in some individuals, with varying degree of severity: Type I (anaphylactic shock) or Type IV (contact dermatitis) reactions. Though EN420 and EN455-3 require a maximum level of protein content of ?50?g/g, this will not eliminate the risk of Latex associated reactions. Choosing a Latex glove with a protein content ?30?g/g (guideline from German Occupation Health & Safety BGIA) can help to further mitigate the risk of Latex reactions. However, the best way to mitigate this risk is to avoid the use of Latex gloves.

When selecting a glove, take into consideration that gloves made from the same material will not necessarily provide the same level of protection

EN420 states that gloves should not cause harm to the user. Though EN420 dictates that gloves should be within a pH range of 3.5 to 9.5 and have Chromium VI content below 3ppm, this does not guarantee innocuousness. Accelerators and process chemicals from the glove manufacturing process may cause skin irritation, particularly in individuals with more sensitive skin. Selecting a glove where accelerators and process chemicals are reduced to non-detectable levels through effective cleaning can help to prevent skin irritation. Biocompatibility per ISO 10993-1 is another method some glove manufacturers use to demonstrate that gloves present a low risk of skin irritation.

In summary, a successful laboratory glove selection process will consider health and safety requirements, application specific requirements and user specific requirements. These requirements consist of five key considerations:

• A glove’s certification and performance with respect to test standards relevant to the risk,
• Identification and mitigation of contamination risks from gloves,
• The physical attributes of a glove required to perform procedures safely and effectively,
• Glove sizing, and
• User susceptibility to allergic reactions and skin irritation.

When selecting a glove, product quality should also be considered. Higher quality gloves guarantee a greater level of consistency in properties that impact the five basic considerations summarised above. Though gloves of a higher quality will conserve their integrity for longer, laboratory gloves should be used only once and disposed of immediately after use.

Further Reading

1. PPE Legislation directives 89/686/EEC and 889/656/EEC,
2. EC Guide to Good Laporatory Practices - Directives 2004/10/EC and 2004/09/EC.
3. Medical Devise directive 93/42/EEC
4. EN374-1:2003 “Protective gloves against chemicals and micro-organisms – Part 1: Terminology and performance requirements”
5. EN374-2:2003 “Protective gloves against chemicals and micro-organisms – Part 2: Determination of resistance to penetration”
6. EN374-3:2003 “Protective gloves against chemicals and micro-organisms – Part 3: Determination of resistance to permeation by chemicals”
7. ASTM 6978-05 “Standard practice for assessment of resistance of medical gloves to permeation by chemotherapy drugs”
8. EN420 “General Requirements for protective gloves”
9. ISO 2859 Sampling procedures for inspection by attributes
10. ISO 16604:2004 and ASTM F1671-97b “Standard Test Method for Resistance pf Materials Used in Protective Clothing to Penetration by Blood-borne Pathogens using Phi-X174 Bacteriophage Penetration as a Test System”
11. EN455-2:2009 “Medical gloves for single-use: Part 2: Requirement and testing for physical properties”
12. EN455-3:2006 “Medical gloves for single-use: Part 3: Requirements and testing for biological evaluation”
13. ISO 10993-1 Biological evaluation of medical devices -- Part 1: Evaluation and testing

Authors: Jaime Cassar, Category Manager and Roberto Greselin, Sales Manager from Clean room & Laboratory PPE, Kimberly-Clark Professional.