Technique May Be the Culprit Behind Class II BSC Contamination
11/01/1999
HOUSTON, TX — Poor technique contributes more than anything else to Class II biological safety cabinet (BSC) contamination, a problem highlighted in a recent American Journal of Health-System Pharmacy report, according to Class II BSC vendors.
The vendors also say they were not aware of studies showing Class II BSC contamination in pharmacies where chemotherapy drugs are prepared [see "Contaminants found outside Class II BSCs," CleanRooms, October 1999, page 1]. The European and U.S. studies claim that pharmacists and nurses using Class II BSCs to handle cytotoxic agents are potentially at risk for cancer and other adverse effects because of the contamination problem.
Authors of the Journal report concluded that exposure to cytotoxics is "commonplace" despite precautions. Many of the vendors believe that workers are not properly following published guidelines on handling cytotoxics, which is the likely cause of most of the contamination. But authors of the report did not examine that factor, though it has come up in other studies.
Because the contamination was documented at every stage of an operation, when the cytotoxics go from one container to another, the problem is clearly attributable to worker technique, says Jim Hunter, a senior engineer and microbiologist at Labconco in Kansas City, MO.
 Vendors recommend rigorous adherence to published operational guidelines when using Class II BSCs to handle cytotoxics. Photo courtesy of Germfree Labs. |
Moreover, as an open system, the Class II BSC has always posed a contamination concern, says Jay Collier, sales manager at Germfree Laboratories, Inc. in Miami, FL. "The Class II BSC is not an absolute containment device and was never intended to be," says Phil Lang, director of sales and marketing at The Baker Company of Sanford, ME. "Release is to some extent inevitable," he adds.
Labconco recommends ducting the BSC to outside air whenever volatile materials are handled, and Germfree stresses good technique, such as gloving and handling methods, in its operator manual to prevent breaching the BSC's barrier. But the vendors concede that rigorous adherence to proper technique is difficult to maintain in busy hospitals and cancer centers, where nurses and pharmacists must perform multiple tasks in addition to preparing the chemotherapy drugs.
Apart from technique, users should regularly certify and maintain Class II BSCs to ensure airflows and filter integrity, says Mark Spence, product specialist at Forma Scientific Inc. in Marietta, OH. The vendor suggests field testing BSCs to the NSF standard 49, Annex F, and lists companies that perform this certification on its Web site at www.forma.com/ .
Any doubt about the ability of personnel to maintain technique and control contamination in a Class II BSC, means a Class III BSC "may be a better solution in terms of worker safety and protecting the product," Collier says. Although Class III BSCs cost approximately twice as much as Class II BSCs, the Class IIIs feature complete containment with double-door airlocks. These products can replace a cleanroom or dedicated clean area and save on gowning time and costs, he adds. But the Class III BSCs also require workers to master different handling techniques from those used with the Class II BSCs, Lang says.
A few Germfree customers are looking at Class III BSCs, but not because of the healthcare worker exposure issue. Collier says that several state pharmacy boards are pushing the higher classification to reduce the rate of IV contamination due to handling technique.
 A hospital pharmacy barrier isolator, such as this unit from Containment Technologies Group, offers a high level of personnel protection. Photo courtesy of Contain-Tech. |
No calls of concern from pharmacists or state pharmacy boards have come into the Park Ridge, IL-based National Association of Boards of Pharmacy (NABP), says executive director Carmen Catizone. Even though Section 9 of the NABP's Model State Pharmacy Act and Model Rules specifies Class II BSCs for cytotoxic drugs, the association will revise its rules if necessary, upgrading its recommendation to a Class III BSC and requiring more training, Catizone says. But until state pharmacy boards or individual pharmacies report problems, the NABP will take no action to revise the rules, Catizone adds. In the meantime, the association has placed the Journal report with the model rules.
"If most of the contamination is occurring because of poor technique, that's an issue our members can address quite quickly by looking at policies," Catizone says. If the contamination is occurring because of equipment problems, state boards can require appropriate equipment changes before a pharmacy is licensed.
Although state pharmacy boards license hospital pharmacies, they do not actually inspect them. Inspections are the job of the Joint Commission on Accreditation of Healthcare Organizations in Oakbrook Terrace, IL, which every three years inspects hospital, home care, and long-term care pharmacies seeking accreditation. The commission inspects pharmacies for both patient and worker safety, and evaluates sterile preparation techniques. It also has a standard calling for preparation of cytotoxics in a Class II BSC.
The Joint Commission was not aware of any studies demonstrating Class II BSC contamination, says Darryl Rich, associate director of accreditation operations. Rich says he is "highly suspect" of the Journal report because it was funded by Carmel Pharma in Goteborg, Sweden, which plans to test its closed, disposable syringe device in the second phase of the study. The Joint Commission will review the report internally, but take no action until more information is available or such organizations as the American Society of Health-System Pharmacists (ASHP) suggest guideline changes, he says.
Both vendors and the Joint Commission should have been aware of the Class II BSC contamination studies, says the Journal report's principal investigator, Dr. Thomas Connor, a genetic toxicologist and associate professor of Environmental Sciences and Occupational Health at the University of Texas (UT) School of Public Health at Houston, TX.
Numerous Studies
Numerous studies have been published on the topic since 1992, Connor says, specifically citing the work of another author of the Journal report, Dr. Paul Sessink, managing director at Exposure Control in Witchen, Netherlands. Sessink has examined Class II BSC contamination in various settings, including pharmacies, he adds. Although these studies were performed in Europe, they were published in international journals. In 1993, a study similar to the current report was published in the Journal of Occupational Medicine. That research was conducted in the U.S. and looked at air samples as well as surface samples.
 The Class II BSC has several design features that help compensate for its open front access. Photo courtesy of the Baker Company. |
Connor defends the integrity of the research and its sponsor, Carmel Pharma. "Are critics 'highly suspect' of the motive for the study or the actual data? Sessink had been demonstrating contamination in European studies before Carmel Pharma was in business," he says. According to Connor, Carmel Pharma contracted with Sessink and researchers in North America to determine if there was a similar contamination study in North America with the prospects of entering that market. "Is this situation any different from pharmaceutical companies, which might have a drug that is better than something already on the market, funding researchers?" Connor says.
"As far as the integrity of the samples is concerned, they were sent to Sessink [who performed the analysis] as coded samples. Only after the analysis was completed was the code broken and the concentrations calculated. All blank samples demonstrated no drug levels whatsoever," Connor says.
In addition, the report did not find that healthcare workers were not following the current guidelines. The researchers did not examine this factor, Connor says. "We believe that the majority of the workers in our study did adhere to most, if not all, current guidelines. However, studies by other researchers have documented less than total compliance to published guidelines by healthcare workers," he adds.
Class II BSCs, while not designed for high level use of toxic agents, are a significant improvement over horizontal flow hoods for preparing chemotherapy drugs, Connor says. When Class II BSCs replaced hoods 18 years ago, researchers documented an immediate reduction, and in some cases elimination, of exposure, including detection of mutagenicity in the urine of workers.
Even though improved analytical techniques now document exposure with the Class II BSCs, Connor and his fellow authors on the Journal report support the use of BSCs for handling toxic agents. "We believe they offer some level of protection, but would recommend that they be vented, preferably 100 percent. One of our biggest concerns is the misconception among healthcare workers that a BSC offers complete protection," Conner says. "Until better technology comes along, we feel it is imperative that all precautions and recommendations are adhered to, including proper handling, proper cleaning, limiting access to work areas, limiting the consumption of food in and around preparation areas, the proper use of protective equipment, proper disposal of waste materials, and all other means necessary to reduce worker exposure," he says.
Eventually, regulators will mandate tighter containment systems, so industries should take the lead to mitigate hazards, says Eliot Cook, current past president of the American Glovebox Society in Santa Rosa, CA and president of Absolute Control Systems, a Weatridge, CO-based custom design/build barrier isolator vendor. Cook says his company has seen an increase in inquiries for cytotoxic applications, but that while healthcare workers recognize the risk, they still prefer the freedom afforded by a more open lab environment.