Clarifying statements about disposable cleanroom garments

04/01/2006

Observations concerning a recent column addressing disposable garment use and markets

By Chuck Berndt, principal of C.W. Berndt Associates

Editor’s note: The following comments and observations by Chuck Berndt were provided to CleanRooms in response to a December 2005 article examining the market for disposable cleanroom garments. After posting the response on the CleanRooms Web site, a number of visitors suggested that we should provide additional visibility to the material through publication in the magazine. Although such responses would normally be handled as a letter to the editor, because of the length and breadth of the discussion, we are providing it here as an “Unfiltered” column.

Some clarifying observations need to be made concerning the article published in the December 2005 issue of CleanRooms on disposable cleanroom garments (see Your Market Analysis column, page 16).

■ The opening remarks state that, “...those operating sterile facilities generally lean toward disposable garments because of contamination concerns (e.g., when reusable garments are returned from the processing facility).” This is not necessarily true. Operators of sterile facilities tend to use disposable garments (nonwovens like Tyvek®) because of their barrier characteristics relative to human sources microbial contamination. As a matter of fact, there are many sterile facilities that use gamma sterilized wovens that are serviced by cleanroom laundries with no more issues relevant to “contamination concerns” from these processing facilities than from use of disposable garments.

■ The article states that, “Suppliers point out that the cost of cleanroom disposable garments is simply a delivered price based on actual usage.” It goes on to state that “...there are many cost variables associated with reusable garments...weekly rental fee...laundering, sterilization, repair...replacement of ruined garments, hangers, totes...bar code charges, fuel surcharges and additional unplanned garment usage charges....”

First, it should be noted that rental fees are based on the cost of the reusable spread over the life of the garment, which is usually 36 months. Comparatively, the weekly rental cost is a very small fraction of a disposable garment. Laundering and sterilization is a cost built into disposable garments as well, since they obviously cannot be used unless they are delivered as cleaned to a standard, and sterilized (where applicable).

Comparing repair costs of reusables (wovens) to disposables is misleading, since a damaged disposable has to be replaced with a new disposable garment at full cost. As a matter of fact, it is standard practice to replace rental garments that no longer meet a standard due to normal wear and tear at no charge (end of garment life). Further, many minor repairs (other than those due to significant abuse) are also done at no charge.

Unplanned garment usage charges as related to reusables, i.e., increases, size exchanges, etc., are no different than the same unplanned circumstances that will also apply to disposables. Increases in personnel or size usage distribution will dictate the need to purchase additional disposables. Accordingly, the comparison to reusables as a savings is misleading. Charges for totes and hangers, if charged, are minimal and certainly no different from charges built into disposables for packaging and delivery. Fuel surcharges are equivalent to increases in shipping charges of disposables due to higher fuel costs. Bar code charges are part of the rental process charge for reusables and not charged separately. If they are, it is by far the exception. Those that make the charge should be called to task and such charges refused.

■ Treating (or coating) disposable garments to make them static dissipative (ESD) is usually ineffective. Such treatments are very sensitive to humidity and temperature, i.e., the controlled environments (cleanrooms) in which the garments are used, not to mention the possibility of added particulate and other unwanted contamination from the treatment itself. The fact of the matter is that for true ESD control, individuals should be using inherently static dissipative garment systems that are grounded (wovens with carbon suffused conductive fibers woven into the fabric). This means the entire garment system and the wearer are grounded, i.e., the skin to the garment system and the garment system to ground. Garment systems mean all parts of the system, i.e., hood, coverall and boots, must be electrically interconnected so that a charge may be fully dissipated to ground.

In less critical situations, conductive floors are used where ESD is achieved through contact with the floor. Sometimes, a user will depend on coronal discharge of the garment system to the surrounding environment (no grounding of personnel). This is very tenuous since ESD, as mentioned earlier, is dependent on humidity and temperature, all of which vary from environment to environment. This use of treated disposables for this purpose is usually ineffective and not better than reusables/wovens with conductive fibers. To achieve true ESD control, there is no substitute for grounding.

■ Mention is made that disposables (Tyvek® in this case) are “breathable” and provide “filtration efficiency for submicron-sized particles and microorganisms....” This is incorrect, since such nonwovens are barrier materials that do not filter or breath per se.

■ Suggesting that disposables are appropriate for paint-spray booths is misleading. Disposables such as Tyvek® are too warm to wear (barrier characteristics) in paint-spray booths, which operate under warmer conditions than standard “controlled” environments. Further, since it is important to reduce triboelectric attraction of particles across wetted surfaces (paint and paint defects), it is important that the garments worn are inherently static dissipative. This is best accomplished with reusables (wovens) with conductive fibers as part of the fabric. Treated disposables will not be effective in reducing the triboelectric phenomenon due to the higher humidity and temperatures found in paint-spray booths. Although some paint-spray operations will use disposables, the majority of such operations use reusables.

■ “Low particle shedding” has never been a general characteristic of disposables. Note that fiber contamination was never mentioned.

■ The article presents disposable garment costs from $1.20 ($30 per case of 25) to $3.20 ($80 per case of 25). There is no definition as to whether these costs represent garments that have been cleaned to a standard for cleanroom application, are sterilized, etc. If a realistic comparison to reusables is to be made in terms of these parameters, these facts must be known (apples-to-apples comparison). A cursory review of disposable coveralls on the Internet reveals garment costs ranging from $1.86 to $8.98 each and higher.

■ The issue of cross-contamination is probably best served with disposables; however, it should be noted that cleanroom laundries do a very good job of controlling cross-contamination at their facilities by employing strict and validated procedures along with relevant equipment and physical adjustments.

■ The article states that, “With disposable apparel, there are no hidden costs: Lost or damaged garments are not part of the incremental charges to the customer.” As was pointed out earlier, this statement is misleading because when disposables are lost or damaged, they must be replaced with new disposable apparel. Obviously, there is a cost to the customer.

■ Recycling of disposable apparel is a very tenuous thing to do. Disposables are not designed for repeated use and will increasingly contribute to contamination. One or two uses, depending on the conditions of use, are possible; however, to make a blanket statement viz., “These garments can be recycled to further reduce costs and encourage environmental conservation” is misleading.

■ On the issue of environmental conservation, disposables are just that-disposables. Once used, they are discarded, and they become part of a larger problem of waste management...this means cost...a hidden cost.

Tyvek® isn’t exactly biodegradable. Accordingly, filling land fills with this material becomes an issue. It is true that some of the disposable apparel may be reused for other applications such as asbestos work, but, eventually, the apparel must be discarded. It should be noted that not all disposable apparel may be reused. Where issues of toxic residues and the like are prevalent, these garments cannot be reused (antibiotics, heavy metals, oncogenic agents, etc.). It is true that some companies will purchase used disposable apparel for recycling; however, this is limited in terms of the number of disposable garments used and those that are recycled. Again, note that not all disposable apparel can be recycled.

■ The statement that air permeability and, hence, comfort of disposables and reusable garments are equal is misleading. One only has to look at air permeability and MVTR (Moisture Vapor Transmission Rate) data for Tyvek® (the most commonly used disposable) with any woven cleanroom fabric.

■ Finally, I do not agree with the statement that, “The most cost-effective choice will always be disposable garments in a medium- to high-risk cleanroom environment.” There are several reusable (woven) fabrics/garments specifically engineered to deal with medium- to high-risk cleanroom environments. These reusables do an excellent job in containing relevant contamination and at being cost-effective for such applications.

Chuck Berndt is the principal in C.W. Berndt Associates. He spent eight years as Group Manager of the Araclean Division of ARA/Aratex Services (now known as ARAMARK Cleanroom Services) and holds a bachelor’s degree in chemistry-biology from Roosevelt University in Chicago. He serves on the Editorial Advisory Board of CleanRooms magazine, is chairman of the Editorial Board of the Journal of the Institute of Environmental Sciences and Technology (IEST; www.iest.org), is both a senior member and Communications Vice President of the IEST, and serves on the IEST Executive Board. He is the recipient of IEST’s 2001 Willis J. Whitfield Award for “his numerous published papers on contamination control and for his support of IEST programs.”