www.cleanroom-technology.co.uk April 2011 CLEANROOM TECHNOLOGY 29

Validation of any glove used in acleanroom is typically a long anddemanding process. In the face of anincreasingly regulated industrial environ-ment, the needs for disposable gloves havechanged dramatically.

Two decades ago it was common practiceto accept standard gloves in PE packaging foruse in the cleanroom. Likewise vinyl gloveswere widespread, particularly in the micro-electronic industry, but a better under-standing of the contamination and barrierissues posed by these types of glove havecontributed to their disappearance.Meanwhile, in the pharmaceutical industry,the practice of using standard surgical gloves(i.e. those where the wallets and outer packingare both made of paper) continued even inaseptic environments.

The adoption of ISO 14644-1 at thebeginning of the decade introduced a singlestandard for cleanroom classification andmade it much easier to understand airborneparticulate cleanliness. A similar con-vergence was taking place in Europe for thepharmaceutical industry, with thepublication of the Guide to GoodManufacturing Practice for MedicinalProducts and its Annexes (EC GMP).

Specific areas, such as the manufacture ofsterile medicinal products, are covered in theannexes. While none of these developmentsfocuses specifically on disposables for use inthe cleanroom, the trend towards theadoption of cleaner practices in anincreasingly regulated environment is clear.

Possibly as a way of trying to fill potentialgaps, the VDI-Society Civil Engineering &Building Services in Germany beganpublishing a series of guidelines known asthe VDI manual of Cleanroom Technology.With reference to consumables to be used inthe cleanroom, this is covered in Annex H ofVDI 2083 Part 5.1 Cleanroom technology -Cleanroom operation.

Throughout the electronic, aerospace andsolar industries, evaluation procedures haveundergone a significant transformation. The

Choosing which type ofdisposable glove is bestfor a particular processis complex. NickGardner, ShieldScientific, reviews therange of choices, limitingfactors and documentsrequired to ensure theymeet cleanroom criteria

same pace of change does not appear to havebeen mirrored in the pharmaceuticalindustry, where in some sectors surgical andmedical examination gloves continue to beused in sterile and non-sterile areas,respectively. Some hospital pharmacies,where cytotoxic drugs and parenteralproducts are prepared, may view personalsafety as the main priority followed bycleanliness of the product. However, underthe influence of ISO 14644 and especially theEC GMP, these areas are undergoing change.

Why do cleanroom applications need aspecific glove? In many cases, the primarypurpose for wearing gloves is to avoidcontamination of the product. Apart fromthe costs associated with high batch failurerates, contamination by biological agents ofparenteral drugs can have seriousconsequences for patients. A similar concernis the need to maintain the cleanliness of thesurrounding cleanroom environment, as thiscan contribute to product contamination.

The first step in the evaluation is thechoice of glove material (see Table 1).

Where electrostatic discharge (ESD) is aconcern, the following points should beborne in mind: Natural Rubber Latex gloves are staticinsulative static insulative materials areconsidered as having a surface resistance ofhigher than 1 x 1012 ohms/sq. The dangerhere is that the charge is held to a certainpoint then released in an uncontrolledfashion. Even with high surface residues,

such as ionic contaminants, the glovesappear to remain static insulative. Nitrile gloves are, in terms of surfaceresistance, considered to be on the borderbetween the insulative and static dissipativeranges. Extensive cleaning, especially indeionised water, may reduce the glovesdissipative properties. Static dissipativemeans that the electric charge bleeds out in acontrolled manner and does not affect theproperties of an item. A glove that is staticdissipative has a surface resistance of morethan 1 x 105 but less than 1 x 1011 ohms/sq. Vinyl gloves (often referred to in the past asESD gloves) offer the best dissipativequalities, by virtue of the high level of surfacecontaminants. Neoprene may exhibit similar ESDbehaviour to nitrile. Furthermore, as manyneoprene gloves have an inner coating (oftenpolyurethane or silicone) to facilitatedonning, it is unlikely that they will haveundergone rinsing in deionised water toenhance cleanliness. Therefore anyfavourable static dissipative properties arelikely to be derived from high levels ofsurface contaminants.

Why is it important to consider thecleanroom classification? Based on ISO14644-1, the lower the ISO Class, the lowerthe permitted concentration of airborneparticles. While the electronic industry willtend to focus on particles and extractables,the pharmaceutical sector will give particularattention to bacterial contamination. For

glovesSelecting

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30 CLEANROOM TECHNOLOGY April 2011 www.cleanroom-technology.co.uk

extractable contamination. Additionally,compared with natural rubber latex, nitrileoffers superior abrasion resistance coupledwith more favourable ESD properties.

Availability of documented performance:A glove manufacturers ability to providecomprehensive and insightful document-ation will not only facilitate the validationprocess, but could ultimately lead to thereduction or even elimination of incominginspection. In this respect, lot-specific data isoften preferred to periodic tests, such asthose done annually or every quarter. Formany years, the electronic industry has beenusing such data as part of its StandardOperating Procedures (SOPs). Increasingly,the pharmaceutical sector has beenrequesting information of this nature tosupport at least the evaluation process.

Specific data that could be requestedincludes: Particle residues by lot for sterile and non-sterile gloves, tested in accordance with IEST RP CC005.3 Endotoxin testing by lot for sterile gloves toconfirm low endotoxin content claim.Testing to be based on the LimulusAmoebocyte Lysate kinetic tubidimetrictechnique (LAL) Sterilisation by lot confirming that gloveshave been sterilised to a Sterility AssuranceLevel (SAL) of 10-6 in accordance withANSI/AAMI/ EN ISO 11137:2006

Product data sheets that are frequentlyfound on manufacturers websites will oftengive a snapshot of the quality of the dataavailable. To assess the potential of themanufacturer to deliver documentedconsistency, requesting copies of certificatesof analysis or conformance for three or morerecent lots could be helpful.

Under Physical Test Data, the totalnumber of samples of final product is shown

those operating under sterile conditions, thepotential for endotoxin contamination willbe of special interest. However, for both non-sterile and sterile applications, the potentialof a glove to cause particle contaminationshould be a source of interest as theseparticles could support microbial life.

Glove manufacturers can ensure that thelowest contamination levels are maintained,by laundering gloves in deionised water,drying under HEPA filter driers and adoptingcleanroom protocol for packing and sortingthe gloves. The latter stage is often done in anISO 5 or even ISO 4 cleanroom.

Other criteria for selection of cleanroomgloves: While operators comfort whenwearing gloves along with their personalsafety are clearly significant factors, anyvalidation process will also want to considerthe supporting documentation.

Feeling and comfort: Feeling and comfortare important since an operator who

experiences discomfort and is unable toperform correctly various tasks may causeerrors. However, just because a glove iscomfortable does not automatically meanthat it is the right choice. Natural rubber latexis probably the most comfortable glovematerial, but brings with it the risk of naturalrubber latex allergy and poor abrasionresistance leading to potential shedding ofparticles in-use.

Gloves with an inner-coating may beviewed as desirable by users, as they offereffortless donning. However, these gloves areunlikely to have been subjected to theextensive laundering (particularly indeionised water) needed for cleanroomgloves to render them low in particles andextractable contaminants.

Nitrile gloves may not provide the samelevel of comfort and dexterity, but multiplerinses in deionised water can produce aglove with the lowest levels of particle and

Table 1: Summary of main features of glove materials

Material Material properties Cleanroom (CR) suitability

Vinyl/PVC Low strength and elongation. For use in CR with low sensitivity to Poor flexibility and ergonomics. particle contamination and where High non-volatile residues and there is minimal need for protection wet particle counts. from microbiological hazards.

Natural Rubber Latex High tensile strength, with For CR applications where there is a good elastic properties. need to avoid particulates and ionic Prone to shedding particles in use. contaminants. Excellent barrier properties Responds well to extra rinse cycles to to biohazards. Compatible with produce gloves low in particles and gamma-irradiation for sterile gloves.ionic extractables.

Synthetic Latex: Good to acceptable elongation and tear Ideal for CR seeking highest cleanlinessNitrile, Neoprene resistance. Good abrasion resistance. levels in terms of low particulate and ionic(Polychloroprene), Following additional laundering, contaminants. Excellent barrier protection toPolyisoprene and possible to produce glove with very biohazards. Suitable for gamma-irradiation Polyurethane low ionic and particle resid