Issues regarding Clothing for Sterile Cleanrooms
The following comments are meant to stimulate discussion and not to provide final answers. In many cases there are claims made which need to be more thoroughly debated. Links have been provided to hundreds of pages of analyses which are meant to support the claims. We will keep revising this overview to reflect the comments of those providing additional insights and counter views.
USER COMFORT AND HEALTH
Marcelo Milani, Medical & Pharmaceutical Protection Marketing Manager at DuPont,
said : “Tyvek® has a low specific weight, a high level of resistance to wear and
tear and abrasion, while also allowing air and moisture vapor permeability. The
material consists of extra-fine filaments made of 100 percent high-density polyethylene
(PE-HD), condensed into a nonwoven under heat and pressure.
Approximately 87 percent of cleanroom
operators would consider switching to a new garment if it was more comfortable
and offered less risk of contamination.
Donning by Design - Kimberly-Clark article in
MVTR (Moisture Vapor Transmission Rate) evaluates the ability to move moisture
through the fabric and translates to more comfort to the operator. Moisture
build-up causes the operator to feel hot due to the increase in humidity between
the fabric and the body.
Jan Eudy of Cintas makes the case in an InterWEBview that reusables are more comfortable due to the high quality fabrics Reusable Garments InerWEBview with Jan Eudy of Cintas, February 2011
Protection against liquid spills
observation that in Europe this is a bigger consideration than in the U.S.
This is also a bigger concern in healthcare such as surgical suites. So there needs to be discussion among hospital and industry specialists
Protection against toxic products
Cytostatics example: Any work with cytostatics requires the effective protection of workers from the dangers of drugs, which can have various carcinogenic, mutagenic and reprotoxic impact. At the same time, it is important to protect the product against contamination from people. Workers must therefore be required to wear suitable protective clothing.. Cytostatics are used as drugs in cancer therapy (chemotherapy) to inhibit the multiplication of tumor cells and are also used increasingly to treat other diseases. However, their toxicity affects not only tumor cells but also healthy cells.
To prevent hazards to staff while handling cytostatics, a range of suitable precautions must be taken. Both clean cleanroom clothing and chemical protective clothing need to meet the same basic criteria for use in a cleanroom: the material must be low-linting, the design must be sufficiently tight, and the danger of collecting particles on the surface of the garment must be minimized. To be suitable for dealing with cytostatics, such clothing must also be comfortable to wear, it must have good electrostatic discharge efficiency and sterilization must be possible. As well as providing product protection, Tyvek® and Tychem® protective clothing and accessories also meet the requirements on chemical protective clothing in Category III and thus personal protection.
Wicking properties for perspiration
Needs to be investigated
InterWEBview with Jan Eudy addresses this subject and her conclusion that reusables are better. Reusable Garments InerWEBview with Jan Eudy of Cintas, February 2011
voiced complaint about Tyvek.
On the other hand it is lighter and this may offset stiffness tendency.
Conclusions of Kimberly Clark survey
Comments about the survey
Thumb loop was developed a number of years ago.
Deterioration of Tyvek with gamma sterilization
It is a
function of intensity.
Deterioration is apparent by the second or third time the garment is sterilized.
Deterioration of reusable garments with processing
See KTH study under laundering below
For the first trial which utilized a permanent finish of propyldimethyloctadecyl ammonium, the treated and non-treated garments yielded similar CFU counts at the soil stage, but the treated garments had significantly lower CFU counts after the final wash cycle. For the second trial which utilized organ functional silanes, the data yielded little difference in CFU counts from the treated garments to un-treated control group for the third trial which utilized oxygenated bleach products, the data gathered yielded little difference in CFU counts from the treated garments to un-treated control group. The treated garments however, showed a very consistent and low, single digit CFU reading, which was very encouraging. The most intriguing result from all three trials was the performance of the control sets of garments. With a few exceptions during the second trial, they performed well, with counts well within an acceptable range, lending credence to the value of a stringent wash and handling process Protection or Hype
In sterile environments, Richard Bryant of Nitritex (Suffolk, UK) states that it’s recommended that cleanroom undergarments be used as an alternative to street clothes. These should be manufactured using nonlinting polyester barrier fabrics. The use of nonlinting polyester undergarments with a good coverall containment system will lower the number of particles carried into the cleanroom environment. Reusable Cleanroom Garments, Part 1, February 2006.
Knitted cuffs-concern of particulate
Seam techniques to avoid particle passage
Special kinds of seam techniques are used for sewing these garments in order to avoid the passage of particles inside or outside the apparel. There are particularly three kinds of seams: • Interlocked stitching: Two pieces of garments are joined together with an interlocking stitching technique. • Double needle stitching: Two pieces are interlocked and then sewed with a double needle. • Layer bound stitching: A third layer of garment is put over the seam and stitched to ensure extra protection Seam Technique for Disposable Apparel
A dispersal chamber at KTH has been used to determine that
relative to microbiological contamination no significant difference was seen
between disposable and reusable clothing washed and sterilized once. But there
was a big increase in particles escaping after 25 wash and sterilization cycles.
Aseptic Production, Gowning Systems and Airborne Contaminants
Most cleanroom garment laundries have validated their processes
for at least 100 launder cycles for the cleanroom garments they supply to the
cleanroom industry. However, Jan Eudy recommend an objective testing of the
cleanroom garment and fabric as well as establishing the efficacy of particle
entrapment, the lack of particle shedding, and ESD efficacy as the criteria for
When Should Cleanroom Garments Be Replaced?
InterWEBview with Jan Eudy of Cintas asserts that there is a big difference between a good laundry and a mediocre one in terms of garment deterioration per wash cycle. Reusable Garments InerWEBview with Jan Eudy of Cintas, February 2011
Q &A procedures: How reliable:
Reusable garments can maintain quality for five years if processed properly Reusable Garments InerWEBview with Jan Eudy of Cintas, February 2011
CCMG requirements more stringent now than before
Hospital pharmacies have special requirements
Garment sizing is highly subjective.. This causes a great deal of confusion and additional cost for anyone trying to maintain a garment program., the IEST committee has worked on developing a standard set of measurements and measurement values to ensure that anyone who is in the market for a cleanroom garment system will receive consistent sizing regardless of who the manufacturer is. Update on IEST WG-CC003 activities / A look at garment system considerations for cleanrooms and other controlled environments
Frocks, 2 piece suits and shoe covers are not recommended for ISO
Class 5 asceptic rooms. The protocol established in IEST-rp-CC03.3 should be
Ask Jan: Protocol for Gowning by Class
More than 50 percent of cleanroom operators reported garments ripping out or billowing due to poor fit.
SINGLE USE VS. REUSABLE FOR STERILE ENVIRONMENTS
The greater the number of changes the more greater the attractiveness of reusables
In sterile environments fabric that is resistant to multiple sterilization cycles must be used in the manufacture of the garments. Garment changes – cleanrooms that require 20 garment changes per week should be looking to use reusable launderable garments. Getting the Best Garment Service
Variation by cleanroom class
Disposable garments are a viable option for some users and applications. Horton says disposables make sense in many ISO Class 6 operations and those that are not conducive to garment cleaning, such as nuclear, some types of food processing, and some pharmaceutical applications. Disposable garments also might make sense for companies that have low gown usage requirements, and they are recommended in biohazardous critical environments (BSL-2, -3, and -4 cleanrooms) and heavy soil applications such as preventive or corrective maintenance of equipment in the cleanroom, according to Eudy The Well Dressed Cleanroom
Research shows that single use garments, which are more
comfortable, easier to don, and minimize contamination are highly valued in the
Cleanroom Clothing InterWEBview™ with Damon Larkin of Kimberly-Clark
Several interviewees contest this claim and say that SMS and Tyvek and similar garments are less comfortable due to heat. Reusable Garments InerWEBview with Jan Eudy of Cintas, February 2011
What is hot to a heavier person may seem comfortable to a thin
person. In an office setting with a constant temperature of 70 degrees F. Some
people will complain of heat and others of cold.
Two variables are the physical make up of the individual and secondly the conditions. The location in the cleanroom can make a difference. The amount of physical activity is another.
Sustainability and Greenhouse Gases
McIlvaine has developed a common metric to measure the water
pollution from reusable garments vs. the CO2 emissions from single use garment
manufacture and disposal.
As TYVEK® protective garments do not incorporate any additives (e.g. halogens), users will incur lower disposal costs. Contaminated protective garments should of course be disposed of after use in the same way as the corresponding hazardous substance (corresponding national/regional legislation and regulations apply accordingly). http://www.dpp-europe.com/Lorem-ipsum-for-heading,91.html?lang=en
Garment Particle Shedding (as opposed to the people inside the garment)
Helmke drum tests are unreliable. Place a garment one way in the drum and get
one result. Place it another way and get a different result (Moschner-Dastex).
More analysis needs to be done of garment particle shedding.
Fabric Choices Single Use
Meltblown Spunbond) material that provides a cloth-like feel and is 25 times
more breathable than TYVEK
For the past 40+ years, disposable cleanroom suits have been made from flash-spun polyethylene fabric. According to industry analysts, flash-spun polyethylene provides filtration efficiency for sub-micron sized particles and microorganisms and is suitable for light splash protection from non-hazardous liquids. Disposable suits also can be made from spunbond meltblown- spunbond (SMS) fabric, which has outer layers of spunbond polypropylene for strength and cloth-like comfort, with middle layers composed of a matrix of microfibers, which creates a torturous path for fine particles and liquids. the Human Element
Tyvek nonwoven material has been upgraded over the years and has
proven to be a good performer in Class 100 (ISO Class 5) to Class 100,000 (ISO
Class 8) environments, depending on garment processing and packaging. Free-fiber
generation at wear points, however, is a disadvantage of this material.. It’s a
breathable fabric that provides filtration efficiency for submicron-sized
particles and microorganisms, and it’s suitable for light splash protection from
non-hazardous liquids. Unlike film laminates, the protective properties of Tyvek
are an inherent feature of the material and cannot be abraded or scratched off.
Disposable Cleanroom Garment Use and Markets, December 2005.
The above claim relative to the free fiber generation at wear points was reported second hand and needs further analysis.
Material degradation becomes a factor for multiple wear garments. The desired Sterility Assurance Level( SAL) is 10(6) insuring a one in one million probability of a garment being nonsterile. This requires more radiation which reduces the life of multi wear garments. The supply chain for multiple use garments is complicated and generally requires contracts with processors of 1 to 5 years. Supply chain for single use garments is less complicated There are two general approaches that a pharmaceutical company can use to assure the quality of incoming garments. • Use internal personnel to monitor and periodically audit • Third party verification of supplier quality system Third part verification requires a certification system (e.g. two ISO standards and or EC Certification) Comfort is another factor . the non woven Tyvek used in single use garments is lighter than woven materials used in multiwear garments. Tyvek is comparable in air permeability but is stiffer. Comfort is typically quantified through air permeability water vapor transmission rates and material stiffness. Apparel System Selection for Pharmaceutical Cleanrooms
Fabric Choices - Reusable
According to John Smith of Precision Fabrics Group (PFG), in the
US market, most of the fabrics sold are plain weaves, whereas in Europe, a much
higher percentage of the fabrics are twill weaves. “Since the fabrics have to
perform the same function of particle filtration, it seems that both can do so
if they are properly constructed,” Smith continues, “. The advantage that the
twill weaves have is that the hand is more supple than a plain weave, although
the plain weaves become more supple after laundering. The disadvantage is the
higher fabric weight and, therefore, garment weight, and potential latent
release of particles if the laundering is not done properly.
Reusable Cleanroom Garments ,Part 2, March 2006.
Burlington C3® is engineered to meet a Class 10 cleanroom's rigid demands for the microelectronics industry. The fabric is designed to guard the product against airborne particles, static dissipative charges, bacteria, and lint. It is made from a dense plain weave 100 percent multifilament polyester yarn with a microengineered carbon fiber inter-woven into a grid pattern.
Stern & Sterns CHEMSTAT 909 and 909A are two antistatic fabrics with a patented
yarn that is an extruded copolymer of polyester and carbon that is impervious to
industrial laundering in excess of 300 washings. CHEMSTAT 909A is a tighter
version of the CHEMSTAT 909 material for use in Class-10 cleanrooms. Both are
100 percent DACRON polyester fabrics employing the patented raised grid conductive
fiber for static dissipation.
DuPont's 100% Dacron polyester yarn is woven into both taffeta and herringbone
weaves. Taffeta fabric is constructed in a plain weave while herringbone is a
heavier broken-twill weave that produces a balanced zigzag effect. Both serve in
many cleanroom and peripheral area applications as an effective barrier for
airborne particles and bacteria filtration. 100% Dacron polyester: Taffeta
2.58 oz/ sq. yd.- Herringbone 4.3 oz/sq yd Excellent resistance to acids and
alkalis Extremely limited tinting·
High resistance to sagging.
INTEGRITY 2000® Precision Fabrics INTEGRITY 2000"is a densely woven filament
DACRON polyester grid fabric designed to meet the quality and performance
standards demanded by the protective apparel industry. This product is highly
fluid repellent and also contains a durable antimicrobial compound.
Teijinselguard Selguard II® is a highly functional Class 100 cleanroom fabric which offers both excellent particulate control and antistatic performance without compromising employee comfort. This non-linting fabric is a continuous filament, 100 percent polyester twill with electrically conductive fibers sleeved in polyester and integrally woven into a grid design.