Sheila Galatowitsch
BALTIMORE—As worker safety becomes a concern, is there a need for a cooperative effort between the cleanroom and safety industries to develop relevant guidelines and recommended practices? Charles Berndt—chairman of the Institute of Environmental Sciences and Technology (IEST) working group on garments,
WG-CC003:Garment system considerations for cleanrooms and other controlled environments—believes so.
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Until the two parties are at the table, cleanroom managers dealing with worker safety issues are left to cull the best advice wherever they can get it.
DuPont’s Protective Apparel division offers several barrier fabrics that protect workers against hazardous liquid chemicals, yet are compatible for cleanroom use. Photo courtesy of DuPont.
Numerous resources are available to help cleanroom users select garments to protect a product or process from human-sourced contamination. But in applications where the worker must also be protected from hazardous substances in the cleanroom—and minienvironments or isolators are not an option—the guidance is less clear.
In fact, the IEST, the industry's principal contamination control organization, keeps a good arm's-length distance from health and safety issues. According to Berndt, the WG-CC003 purposely avoids the topic. 'Safety is an entirely different animal from contamination control. Because of liability concerns, there's always been a tendency for the two issues to be kept separate,” says Berndt, a CleanRooms Editorial Advisory Board member and consultant with C.W. Berndt Associates (Highland Park, IL).
Much of what guidance is available in the U.S. comes from the government agencies responsible for worker safety. Yet these resources don't consider product contamination control in their protective clothing recommendations. Ultimately, responsibility for designing a garment scheme that protects both workers and products is up to the cleanroom manager and industrial hygienist. And it's not an easy task. The goal is to choose garment fabrics that will protect workers from accidental exposure to hazardous substances, but won't contaminate the cleanroom. These so-called 'barrier” garments must also be comfortable to wear and affordable for everyday use. It's a tall order, and sorting through competing vendor claims can further complicate the decision-making process.
Biosafety experts advise starting a selection process by considering the worker risk factor to the hazard in question, whether it is chemical, biological or physical. The risk factor will determine the level of protection and type of personal protective equipment required. This method of 'working backwards” ensures that human safety remains paramount, says Robert Powitz, Ph.D., a consultant and registered biosafety professional with R.W. Powitz & Associates (Old Saybrook, CT).
For example, Material Safety Data Sheets (MSDs), required by the Occupational Safety and Health Administration (OSHA) for all chemicals, specify exposure hazards and the level of protection needed to work with that chemical. The Centers for Disease Control (CDC) and the National Institutes of Health (NIH) set protection levels for biological agents, and the National Institute for Occupational Safety and Health (NIOSH), the industrial hygiene arm of OSHA, identifies protection levels for physical hazards such as ultraviolet light and heat exposure.
NIOSH also has a guide for evaluating the performance of chemical protective clothing, which is available on its Web site at www.cdc.gov/niosh/homepage.html. The 10-year-old document, Publication No. 90-109, describes a selection process that includes evaluating the workplace, obtaining samples of candidate clothing, testing the samples under the conditions in which they will be used, selecting the best candidate clothing, then monitoring its use in the workplace.
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Kappler Protective Apparel and Fabrics says its microporous composite fabrics, designed to protect workers against liquid hazards, are more comfortable than other fabrics.
For applications where workers are at risk of accidental chemical splashes, nonwoven Tyvek provides some measure of protection, but its primary purpose is to protect the workstation and worker against dry particle contamination, says Peter Gabele, cleanroom segment manager at DuPont Protective Apparel (Wilmington, DE). DuPont offers other barrier fabrics, such as Tyvek QC and Tychem SL, that provide a higher level of protection against many hazardous liquid chemicals. 'We have limited-use fabrics for most liquid and dry hazards in question, and we can address the cleanliness of the environments where the barrier fabric will be used,” Gabele says. In environments where sterility is not an issue, workers can layer a barrier garment, such as an apron with sleeves, over traditional cleanroom apparel. But for aseptic environments, the ability to sterilize barrier fabrics becomes an issue. If the fabric cannot be sterilized, workers can wear the protective apparel against the body with the sterile cleanroom garment on top.
Layering garments in this fashion makes it a challenge to keep workers cool, dry and comfortable. Kappler Protective Apparel and Fabrics (Guntersville, AL) claims its barrier garments made from microporous composite fabrics are inherently more comfortable when layered because they 'breathe” better than other barrier fabrics. The company also says the fabric is clean enough for use in ISO Class 5 (Class 100) cleanrooms, a claim DuPont has publicly disputed but one Kappler stands by.
Both DuPont and Kappler back up their product claims with multiple third-party tests to American Society for Testing and Materials (ASTM) test methods. Powitz says users can generally trust this test data, but in the case of conflicting claims users should do their own research. If in doubt about a fabric's protective capabilities against a specific hazard, users can query NIOSH or the National Safety Council. If in doubt about a fabric's suitability for cleanroom use, Powitz suggests testing the garment for its shedding characteristics to see if it conforms to cleanroom protocols. 'Research it until you are comfortable with it,” he says.
Users should also ensure that test methods correlate to their particular exposure scenario. 'Many people want to get their hands on a test result without fully knowing if the information replicates their exposure scenario,” says Philip Mann, Kappler's manager of technical services. Kappler has a software program that helps users assess hazards and identify appropriate test methods and the level of protective apparel necessary. Depending on the hazard assessment, the garment solution could range from an apron to a totally encapsulated suit. And although a barrier fabric may have many chemical barrier applications, it is the users' responsibility to determine the level of toxicity and the proper personal protective equipment needed, says Gabele. DuPont provides chemical permeation data for each of its fabrics on its Web site at www.dupont.com/tyvek/protective-apparel.
Later this month at CleanRooms East in Baltimore, instructor Brad Whitsel plans to address worker safety considerations as part of his tutorial on developing and validating a cleanroom apparel program. Whitsel, a cleanroom industry marketing, training and project management consultant based in Chambersburg, PA, says that worker safety is a complex issue, involving a huge number of components and variables. 'There may never be a formula or comprehensive 'recommended practice,' ” he says. 'It will always be essential to an effective worker safety program that every aspect of each application be critically evaluated and addressed, and every application will be unique. Documented evidence must be assembled and informed decisions made accordingly because the ultimate responsibility for success lies with management.”