Assessing single-use medical gloves to EN 455

Are you familiar with the European requirements for examination and surgical gloves?

It is essential that medical gloves provide a barrier to prevent the transmission of harmful bacteria and infections from person to person. EN 455 parts 1, 2, 3 and 4 are the standards designed to assess single-use medical gloves to determine their ability to provide a protective barrier between a healthcare worker and the patient. The last thing either party wants is an issue with the gloves’ protective barrier. This would present a risk to both the healthcare worker and the patient, as the protective barrier would be compromised, thus leading to the risk of harmful bacteria and infections being transmitted.

Glove performance relating to the wearer’s personal protection aspects are assessed under the PPE Regulation (EU) 2016/425 and in the requirements standards EN ISO 21420 and EN ISO 374-1.

Before placing medical gloves onto the market within the European Union, it is necessary to ensure that they satisfy all the relevant regulations and that manufacturers can demonstrate ongoing conformity. The ‘European Medical Device Regulation’ (MDR) – (EU) 2017/745 – is the current regulation that governs the production and distribution It is important that economic operators (manufacturers, importers and distributors) know their legal obligations under the MDR. While these will not be discussed in this article, examination gloves are classified as ‘class I’ medical devices (intended for transient uses that are not invasive) whereas surgical gloves are ‘class IIa’ medical devices of medical devices in the European Union and has replaced the ‘Medical Devices Directive’ (MDD).

It is important that economic operators (manufacturers, importers and distributors) know their legal obligations under the MDR. While these will not be discussed in this article, examination gloves are classified as ‘class I’ medical devices (intended for transient uses that are not invasive) whereas surgical gloves are ‘class IIa’ medical devices (surgically invasive devices) and require technical documentation and ongoing conformity to be reviewed by a Notified Body.

EN 455-1 – freedom from holes

EN 455-1:2020+A1:2022 – ‘Freedom from holes’ tests the glove’s ability to provide a protective barrier. This test involves a glove being secured on a tube and suspended vertically. One litre of water is poured into the tube and the glove is immediately inspected visually for water leakage (figure 1). The inspection is repeated after two to three minutes.

Clause 6 of EN 455-1 requires statistical sampling in accordance with a standardised acceptance quality level (AQL). General inspection level 1 and code letter ‘L’ are specified and, using the sampling scheme in ISO 2859-1, 200 gloves are tested. The inclusion of an AQL level for surgical gloves was an addition in the 2020 version of the standard.

For the gloves to be compliant with the requirements, examination gloves must achieve an AQL of 1.5 and surgical gloves must achieve an AQL of 0.65. Based on this AQL, this equates to a maximum of seven permitted failures for examination gloves before the overall batch is considered to fail the requirements. For surgical gloves, a maximum of three failures are permitted before the batch is considered to fail the requirements of the standard based on this AQL.

EN 455-2 – physical properties

This standard has specific requirements and test methods for the assessment of single-use medical gloves for both examination and surgical applications. The standard has requirements for the length and width dimensions of the gloves, as well as tensile strength as the gloves were received and after they have been aged.

To measure the length and width of the gloves, a graduated rule with a rounded tip is used which replicates a fingertip (figure 2). Thirteen gloves of each size are assessed and the median result is calculated. This median value is then used to determine if the gloves meet the requirements for dimensions specified in the standard.

To measure the length, the rule is placed on the tip of the middle finger and a measurement is taken at the cuff. For the width measurement, the distance between the thumb crotch and the index finger crotch is measured, with the centre point being where the width to the base of the little finger is measured. Care should be taken and the gloves should be handled as gently as possible in order to not stretch the glove prior to measurements being taken. The requirements for the dimensions are split into ‘surgical’ or ‘examination’ gloves, and each glove type has different size tolerances for both the length and width.

For the tensile strength, (force at break) the test specimens are prepared from a flat and smooth section from the palm, back of hand or cuff areas of the gloves (figures 3 and 4). The thickness of the test specimen is measured and a second measurement is taken within 13 mm from the tip of the middle finger. This middle finger ‘wall thickness’ measurement is performed on each of the 13 gloves from which a test specimen is prepared, and the thicknesses at the different areas are compared to determine if a correction factor is required.

It is recognised that because of design or manufacturing processes, the fingers of gloves may be significantly thinner, and therefore weaker in terms of force at break than at the areas from which the test specimens were taken. If the difference in thickness is less than 10 per cent, no correction is required. However, if the difference is greater than 10 per cent, a correction factor based on the glove thickness is applied. The test is performed using a tensile testing machine with the jaws moving apart at a constant speed of 500 mm per minute until the test specimen breaks. The median value from the 13 individual results is compared to the requirements in table 1 to determine compliance with the standard.

The ‘force at break’ test is performed on the received gloves after accelerated ageing. The ageing process consists of placing the gloves in an air circulating oven at 70°C for one week before they are tested. The requirements for tensile strength before and after ageing are split into three categories: ‘Category a’ is for surgical gloves, ‘Category b’ is for all examination gloves except those made from thermoplastic materials and, finally, ‘Category c’ is applicable to examination gloves made from thermoplastic materials – for example, polyvinyl chloride (PVC) and polyethylene (PE).

EN 455-3 – biological evaluation

EN 455-3:2013 provides requirements and test methods for the evaluation of the biological safety of single-use medical gloves. The standard states that manufacturers must be able to provide details of any harmful chemicals used in the production of their gloves upon request, and that manufacturers take precautions to reduce the risk of exposure to the end user. As well as these general requirements, EN 455-3 also gives specific requirements for the labelling of gloves, depending on their potential hazards.

The first of these relates to the presence of endotoxins, which are derived from bacteria and may arise due to contamination of raw materials such as process water during manufacturing. While there is no specific requirement, the standard states if a manufacturer wishes to label its products as 'low endotoxin gloves', the amount of endotoxins present must not exceed 20 endotoxin units per pair of gloves when assessed according to clause 5.1.

The labelling requirement of this standard states that medical gloves must provide a prominent indication of whether the gloves are ‘powdered’ or ‘powder-free’. Gloves which contain less than 2 mg of powder per glove are classified as powder-free, while products which exceed this value are considered to be powdered gloves. The test method used to determine this is EN ISO 21171:2006, which lists several different procedures, depending upon the type of gloves being assessed.

The testing is slightly different for gloves which are believed to be powdered than for those which are claimed to be powder-free. There is also a procedure specifically for surgeons’ gloves, which involves testing a larger number of samples than would be used for examination gloves. For sterile powdered gloves, there are also additional requirements for labelling, as they must contain a warning that the powder should be aseptically removed prior to operating procedures. Furthermore, the use of magnesium silicate (talcum powder) as a powder in gloves is prohibited.

The final requirement for the biological safety of medical gloves relates to the presence of latex proteins. A significant portion of the population have an allergy to natural rubber latex, and this can lead to severe anaphylactic reactions. For this reason, manufacturers of latex gloves are required to monitor the amount of extractable proteins and to save records of this information.

The amount of extractable latex proteins in gloves is determined using the Modified Lowry Method specified within Annex A of EN 455-3. Regardless of the levels of extractable proteins, gloves which contain natural latex must bear a warning. This warning must be present – at a minimum – on the smallest packaging unit of the gloves. It must include the symbol for latex, as well as comment that it is present and can cause allergic reactions, including an anaphylactic response.

In addition, the labelling clause of EN 455-3 states that products containing latex must not include any indication of relative safety, such as claims of low allergenicity or low protein content. Other labelling requirements include using the symbol shown in figure 5 or an equivalent warning statement where there is a residual risks of causing Type IV allergies. Chemical ingredients such as accelerators, antioxidants and biocides could be added during manufacturing or be known to be present in the product and may cause Type IV allergies.

EN 455-4 – shelf life determination

EN 455-4:2009 evaluates the shelf life of single-use medical gloves and addresses certain essential requirements detailed in the MDR. Manufacturers of medical devices must have adequate data to support shelf life claims and ensure that they are available for review by regulatory authorities. Medical glove manufacturers need to test properties such as force at break, freedom from holes and – for sterile gloves – pack integrity.

The standard states that once the gloves are placed onto the market, the manufacturer should conduct a shelf life study. This could be by means of accelerated ageing but, at the same time, the manufacturer should enter into performing a real-time shelf life study. For accelerated ageing or real time studies, a sufficient number of gloves taken from at least three different lots should be selected and should remain in the packaging. The number of gloves selected should allow for the freedom from holes and force at break testing to be performed in accordance with EN 455-1 and EN 455-2.

In addition, within the standard there is a requirement to assess the pack integrity for sterile gloves. The guidance for accelerated ageing studies in Annex B recommends that a minimum of four elevated temperatures are selected with a minimum of five time points at each temperature. The preferred duration of the study is 180 days, although 120 days is the minimum. These requirements are assessed at various points throughout the ageing process. It is recommended that additional gloves are subjected to the study, as this will allow for any retesting which may be required.

If the gloves are found to have a real-time shelf life inferior to any claims prior to the conclusion of the shelf life accelerated ageing study, the manufacturer must inform the relevant regulatory authorities and change the shelf life claims. Shelf life claims which are based on accelerated ageing are not to exceed three years.

In summary

Single-use medical gloves are assessed as medical devices in accordance with the MDR, using the requirements and test methods specified in the EN 455 standards. These consider the glove performance – such as freedom from holes and force at break – from the perspective of protecting the patient. However, aspects from the perspective of protecting healthcare professionals are considered in protective glove standards.

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