August 7, 2000 - Occupational Exposure to Tuberculosis

The American Society for Microbiology (ASM) appreciates the opportunity to submit a statement to the Institute of Medicine (IOM) Committee on Regulating Occupational Exposure to Tuberculosis for consideration as it prepares its short-term study of occupational exposure to tuberculosis. The ASM is the largest single life science society in the world with more than 42,000 members representing a broad spectrum of subspecialties, including microbiologists who work in biomedical, clinical, public health, and industrial laboratories. The mission of ASM is to enhance the science of microbiology to better understand basic life processes and to promote the application of this knowledge for improved health and for economic and environmental well-being.

ASM members employed in clinical laboratories have the primary responsibility for detecting and diagnosing patients with tuberculosis. Mycobacterium tuberculosis research conducted by members of the ASM, is the world's best answer to permanently eradicating the dreadful scourge of tuberculosis. ASM, therefore, has great interest and concern for the safety of all clinical and research laboratory workers.

From the perspective of laboratory practices and worker safety in the clinical and research laboratory setting, the ASM will address its comments to some of the questions raised in the IOM Committee's "Guidelines for Written Testimony," including our concerns with the most recent version of the OSHA proposed rules for Occupational Exposure to Tuberculosis, and the strengths and limitations of the Centers for Disease Control and Prevention (CDC)/National Institutes of Health (NIH) Biosafety

in Microbiological and Biomedical Laboratories, (4th Edition, May 1999) guidelines (BMBL) for elaborating these rules. Because the laboratory is governed by different CDC guidelines (BMBL) than the balance of the hospital environment, ASM will not conform strictly with the specifications of the IOM request for written testimony. Attached to this statement are previous comments prepared and submitted by ASM in response to the 1997 OSHA proposed rule, which address the worker safety issues more specifically.

Laboratory Practices and Biosafety

The ASM is concerned about the most recent version of the OSHA proposed rules on Occupational Exposure to Tuberculosis, because the rules that pertain to laboratory practices omit provisions for many laboratory employees who are at risk. Laboratory employees at risk for tuberculosis infection include those who work in the pathology section, especially the frozen section room, the cytology procedure room, and the autopsy suite. They may also include employees who work in the general clinical laboratory, in the chemistry, hematology or bacteriology laboratory.

Provisions in the OSHA proposed rules refer to the BMBL guidelines, which apply only to the mycobacteriology laboratory and indirectly for phlebotomists. Safety provisions for specialized procedures such as work with the microtome cryostat are unfortunately absent in the document. Their inclusion would greatly enhance protection for laboratory employees and the surgical suite. Phlebotomy safety provisions are also not specifically provided in the rules, but would be those appropriate to protect nursing and other general hospital employees who have patient exposure. The OSHA proposed rules include provisions only for the phlebotomists and mycobacteriologists, omitting some 95 percent of laboratory employees.

The OSHA proposed rules are problematic for the mycobacteriology laboratory. The OSHA proposed rules are based upon a former edition of BMBL, and do not reflect the changed requirements in the latest edition of the guidelines. For example, the OSHA proposed rules allow the laboratory director to designate the biosafety level of the mycobacteriology laboratory and then specify that the appropriate safety precautions are provided in the most recent edition of the BMBL. However, the updated version of the BMBL no longer allows the laboratory director to designate biosafety levels; rather the guidelines provide specific guidance about the biosafety levels that should be used. Implementing the proposed rules that cite the BMBL, therefore, would create conflict and confusion for laboratories.

If we assume that the new BMBL guidelines are to be followed rather than the conflicting allowance for laboratory director discretion in the OSHA proposed rule, then Biosafety Level 3 would be applicable for all cultures of Mycobacterium tuberculosis and M. bovis. The proposed OSHA rule purports to apply to all worker settings from research, where it may be too lax, to clinical laboratories, where it may be too strict. The specification that Biosafety Level 3 be used for manipulation of cultures may be too lax for adequate containment of large volumes of cultures that are aggressively aerosolized, as may happen in a research or industrial environment.

The designation that Biosafety Level 3 be used for all culture work presumes that all such work is equally hazardous, when in fact, cultures on solid media are thought to be of less risk than those cultures in liquid media. Moreover, small volumes of liquids that are not actively aerosolized might be safely manipulated using Biosafety Level 3 practices in a Biosafety Level 2 facility. ASM recommends that the manipulation of cultures be perceived as a continuum of increasing risk, with increasing containment appropriate to the level of risk.

The ASM notes that the proposed rule references a former edition of the BMBL which is inconsistent with its latest, updated edition. Also, the ASM believes that the guidelines in the BMBL, which allow for flexibility, are not appropriately specific to be considered for a set of regulatory rules. For example, the BMBL does not specify that a specimen set up procedure, which actually ends with a "culture," does not need to concomitantly become Biosafety Level 3 as the set up of the culture is completed. Under a regulatory environment, however, the flexibility would be lost, necessitating the employment of Biosafety Level 3 throughout the entire set up procedure. In reality, a culture tube or bottle does not represent an increased hazard until the culture has been incubated and the organisms have multiplied.

In addition, the BMBL provision for the management of clinical specimens calls for Biosafety Level 2 for non-aerosol procedures and use of a biosafety cabinet for aerosol generating procedures. This might lead some to process and set up specimens outside the biosafety cabinet even though, by inference, this would be contraindicated. Highly trained people who read the guideline will understand the conflict but it is not these individuals who are at risk of misinterpretation, which could be potentially dangerous.

Education and Training

When there is tuberculosis transmission in the laboratory, there is a tendency to blame the physical facility when, it is often the practices in the laboratory that are at fault. Currently, there is inadequate conceptualization by laboratory staff members about the aerosol itself. The potential for the presence of a residual aerosol in a used pipette or flask may be unrecognized and the equipment removed from the biosafety cabinet before the aerosol is exhausted from the glassware. If left by the autoclave or sent to the trash, the aerosols become hazardous for other ancillary staff.

Training of staff is urgently needed. Innovative training programs should be developed that teach concepts of aerobiology. Increasingly, training will be urgently needed as less trained and experienced staff members are hired in the new medical care climate. Alternatively, new restrictions on laboratory employees' background and education should be considered. The "bells and whistles" of a Biosafety Level 3 facility may provide a false sense of security and the practices could deteriorate even more. People tend to believe that they are protected by the facility. However, the protection offered by a Biosafety Level 3 facility is primarily, if not exclusively, to individuals who are outside the boundaries of the facility who might otherwise get exposed by air interchanges with contiguous or connected spaces. ASM supports the concept that a medical technologist with a baccalaureate degree be considered the minimum qualification for individuals who work with tuberculosis cultures.

Respirator Requirements

There is no reference to respirator requirements in the OSHA proposed rule. ASM members directing clinical microbiology laboratories were surveyed several years ago and contributed data that, in aggregate, suggested that operation with good practices could sustain a safe environment without the complementary use of respirators. This provision may be applicable in the clinical setting but inapplicable in the more intense research or industrial setting. Specificity about respirator requirements would remove the confusion that exists.

With regard to the clinical laboratory setting, ASM suggests that the laboratory director have discretion in deciding whether to use respirators to complement the Biosafety Level 3 operations. In laboratories where respirators have historically been used, there is a tendency to consider them necessary. Among other laboratories, however, the perceived need to comply with a rule may be the only driving factor. There is no reason to believe that respirators should be necessary when operating only with specimens, using a good set of Biosafety Level 2 practices. In fact, such use would be contradictory. Wearing a respirator in a space where the air communicates freely with other spaces suggests that people in the other spaces are being placed at risk. Given this consideration, respirators would be contraindicated for use in Biosafety Level 2 laboratories and in those laboratories using Biosafetyly Level 3 practices in a Biosafety Level 2 lab.

The proposed OSHA rule also creates an impossible situation in the health care environment where an attenuated strain of M. bovis is used for therapeutic purposes. It is administered to patients who subsequently eliminate it in their urine. Neither the patient nor the pharmacist or nurse would, or could, be confined in a Biosafety Level 3 environment. Strictly applied, however, the proposed rule would make this necessary because of wording in the BMBL designating M. bovis subject to the same safety constraints without reference to strain.

Biosafety rules and/or guidelines with respect to tuberculosis exposure will have an enormous impact on laboratory workers and the visitors, patients and staff who breathe the air of the building in which they work. Although the same is true for those directly involved with patient care, the order of magnitude for a laboratory worker who works with organisms amplified by culture, is much greater. The ASM appreciates the IOM Committee's consideration of its concerns regarding laboratory practice and worker safety, and would be pleased to provide additional information as the Committee continues to study this important issue.