Re: Limited re-opening of the rulemaking record for Occupational Exposure to Tuberculosis, 67 Federal Register 3465, January 24, 2002

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Friday, May 24th 2002

Docket Office
Docket H-371, Room N-2625
Occupational Safety and Health Administration
U.S. Department of Labor
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Washington, DC 20201

Dear Secretary Chao:

On behalf of the American Hospital Association (AHA), we would like to express our appreciation for this additional opportunity to comment on the Occupational Safety and Health Administration's (OSHA) proposed rule to prevent occupational exposure to tuberculosis (TB). We are responding to your request for review of comments made by the peer reviewers regarding OSHA's draft final risk assessment and the Tuberculosis in the Workplace report issued by the Institute of Medicine (IOM).

The AHA represents nearly 5,000 hospitals, health care systems, networks and other health care providers, as well as more than 28,000 personal members, including many health care professionals who are covered by the scope of the TB regulation proposed by OSHA. We support efforts to reduce the risk of transmission of tuberculosis to workers, patients and visitors in the health care setting. The AHA has provided guidance to hospitals for over two decades regarding the risk of transmission of TB to patients and health care workers and measures to reduce risk. OSHA is aware of the AHA's efforts to ensure implementation of the Centers for Disease Control and Prevention (CDC) guidelines in our hospitals. This guidance has included resource guides, sample hospital-wide policies, teleconferences and briefings on new federal guidelines and requirements for TB control.

We believe that these efforts have helped reduce the prevalence of TB in the United States to the lowest level in recorded history. In fact, according to a recent report from the Advisory Committee for the Elimination of Tuberculosis (ACET), between 1992 and 2000, there has been an unprecedented 45 percent decrease in incidence of TB in the US.13 The AHA remains committed to supporting hospital compliance with CDC guidelines in order to sustain these important gains in public health for patients and health care workers.

The AHA has on numerous occasions expressed concern with proposed OSHA requirements that go beyond the provisions of the CDC guidelines. Hospitals have spent considerable time and resources since 1994 in developing TB control programs consistent with the 1994 CDC guidelines. Proposed OSHA requirements that go beyond these recommendations would place an additional and unneeded burden on all hospitals.

The following comments address only the specific areas OSHA has re-opened for comment, focusing primarily on the comments made by the peer reviewers on OSHA's draft final risk assessment and the IOM report.

Evidence that OSHA has Overestimated Occupational Risk from Exposure to TB

OSHA's quantitative risk assessment is intended to estimate the annual and lifetime risk of TB infection to workers occupationally exposed to M. tuberculosis. The AHA believes, based on the reviewers' commentary as well as the discussion in the IOM report, that OSHA has overestimated the occupational risk from exposure to TB.

The elements OSHA uses to estimate annual and lifetime risks involve: a) tuberculin skin testing (TST) and two-step baseline testing (e.g., booster effect); b) community sources of exposure and disease; and c) the basis for determining attributable risk. We will address each of these elements separately below.

a) Tuberculin skin testing: OSHA uses the results of TST to indicate infection. While TST is the best indicator available for infection (but not for disease), due to the many limitations of the test material and testing process, the rate of false positive results is high. OSHA did not sufficiently take these limitations into consideration in developing their risk estimates. These limitations include:

  • Placement (how applied)
  • Reading the test (size, induration,)
  • Interpretation (variation in readers)
  • Variation in tuberculin products (change in product use)
  • Boosting, sensitivity, specificity, and positive predictive value

The IOM report, Tuberculosis in the Workplace,3, 4 appropriately describes the variation and other problems with tuberculin products. Further, because two-step baseline testing (i.e., boosting phenomenon) was not performed in the studies OSHA used to estimate occupational risk, there is likely an overestimate of the true incidence of infection due to increased numbers of false positives, particularly in low risk populations.3 In his peer review report, Menzies also cites the tendency for difficulties related to TST and different methods of estimating risk to lead to overestimates.2

b) Community sources of exposures: The ability to distinguish community-acquired transmission of TB from nosocomial (hospital-based) transmission is critical for estimating risk. The OSHA

studies used to estimate risk did not adequately control for community sources of exposure. For instance, at Grady Memorial Hospital, where a comparison group was assessed, two-step testing was not done, sources of exposure were not determined and the study did not control for other confounding factors. The use of disease registries have a similar problem: they cannot differentiate occupational from community exposures.5 In his peer review report, Nicas references the problem of overestimates due to ignoring the age at which infection occurs, regardless of the source of exposure.1 We realize that OSHA has struggled with this issue; nonetheless, the end result is an overestimate of infection.

c) Basis for determining attributable risk: It is evident that OSHA compares data from different sources and from different time periods, and uses different methodologies to determine the attributable risk due to occupational exposure. While we understand that OSHA is limited in the data available for such assessments, the methodologies used have major problems. For instance, OSHA calculations for attributable risk due to occupational exposure are developed from health care workers' skin tests taken during outbreak periods (1989-91; 1994), and in facilities with high numbers of TB cases. These rates are applied to different populations at a much later time (1998), past the peak of TB incidence. Extrapolating these data to states not experiencing outbreaks and to a later time period results in an overestimate of the attributable risk due to occupational exposure2, 6 and underestimates community-based exposure.

In addition, OSHA used outbreak studies from Grady Memorial Hospital in Georgia, and Jackson Memorial Hospital in Florida, states with the highest rates of TB cases in 1994. OSHA extrapolated data obtained from these two facilities during outbreaks, and applied them to health care workers throughout the 13 highest TB incidence states. These facilities are not representative of health care facilities nationally since they serve the highest risk populations in their respective cities and states. This data should not have been used to extrapolate beyond these facilities for the specified periods of time.6 Once again, while these data may be fine when applied to limited populations and specific conditions, they are certainly not appropriate for use in the current OSHA risk assessment.

Further, when calculating rates for "moderate risk" states, OSHA also uses older data that has limited application for risk estimates in 2002. For example, OSHA uses nearly 20-year-old data from North Carolina (1984) to provide estimates of risk in moderate risk states. The peer reviewers refuted the validity of this study, noting that two-step testing was not performed and that people in North Carolina (not just the eastern section) are likely to have been exposed to atypical mycobacteria, resulting in increased levels of false positive results. Both sets of peer-reviews obtained by OSHA (published preliminary risk assessment and current draft final risk assessment) criticized the use of this data.1 In fact, in his current review Menzies states that the validity of this data is questionable and insufficient, and he notes that its use jeopardizes the entire analysis.2

Concerns About Equating a Positive TST with a Material Impairment of Health

OSHA's statutory requirements for promulgating a rule have previously been based on the likelihood of death due to occupational exposure over a 45-year working lifetime. In this risk assessment, OSHA has concluded that positive TST is a material impairment of health or functional capacity.

The AHA believes that this conclusion is based on a weak premise, since a positive TST is taken as the proxy for infection. The fact is that the great majority of individuals identified with latent tuberculosis infection never develop active disease, have no symptoms and do not infect others.3 Furthermore, the IOM report describes in detail the problems with TST such as: relatively crude material for the Purified Protein Derivative (PPD); the poor positive predictive value of TST whenever the probability of infection is less than 1 percent; variation in tests administered and reading of the induration even among experienced observers; reports of false-positive reactions in skin testing programs that switch skin testing products; a lack of an independent method to determine infection; false positive tests in uninfected persons due to cross-reactions in persons who have been vaccinated with BCG; environmental exposure to other mycobacteria, and many other problems.4

In summary, the TST is a poor indicator of actual TB infection, particularly in areas where the prevalence of TB is low. And, given the current rates of TB disease, the majority of the country would fall into the low prevalence category.4 It simply does not make sense to justify the issuance of an OSHA TB standard solely on the basis of studies utilizing this test. Instead, the AHA believes that, given the limitations of the TST, such a standard, if indeed it is needed, should be based on the incidence of TB disease or mortality due to TB in health care workers.

OSHA Overestimates Rate of Progression from Infection to Active TB

OSHA calculates that there is a 10 percent likelihood of an individual progressing to active TB if they are infected and left untreated. The AHA believes that OSHA's estimate is, at best, overstated by 50 percent. Other reviewers have published estimated rates as low as 3 or 5 percent.7 The current peer reviewers (Menzies and Nicas) indicate that the data to support the 10 percent rate is sparse.1, 2 After discussing the computational challenges, Menzies recommended a lower rate to represent lifetime disease -- 3.7 percent for the first 10 years following infection and 0.05 percent to 0.1 percent annually thereafter, for a cumulative lifetime risk that would vary according to one's age at time of infection. Another reviewer, Daniels, states that tuberculosis mortality risk in immunocompetent health care workers with tuberculosis not due to a multi-drug resistant organism is probably close to zero.7

The IOM report addresses this issue in detail,3, 6-8 and notes that OSHA's 10 percent figure overstates the risk for most workers since it was derived from studies of young children. The IOM report notes that the rate of progression from untreated infection to active disease varies by age, with lower rates for working age adults. Further, they note that treatment of latent TB infection substantially reduces the risk of progression to active disease and healthcare workers tend to be healthier, and are more likely to have access to care. All these factors decrease the risk of active disease and death in healthcare workers.

Questionable Basis for Promulgating a Final TB Standard

The Occupational Safety and Health Act requires that, prior to the issuance of a new standard, a determination must be made, based on substantial evidence in the record considered as a whole, that there is a significant health risk under existing conditions and that issuance of a new standard will significantly reduce or eliminate that risk. The AHA questions whether enough such evidence exists to support the promulgation of this TB standard.

As OSHA is aware, the AHA has supported efforts to reduce the risk of transmission of TB in the workplace, including enforcement of CDC's Guidelines and OSHA's compliance directives. We have focused our support on OSHA proposals that are in agreement with the CDC's recommendations. And these measures appear to be working -- since 1993, the incidence of tuberculosis in the United States has decreased to the lowest levels ever reported.

Furthermore, the IOM report also makes the following points, which we believe argue against a new regulatory approach from OSHA and instead support sustained implementation of CDC guidelines (particularly administrative and engineering controls) and the focus of resources on at-risk populations in the community.

  • The primary risk to health care, corrections and other workers now comes from patients, inmates, or clients with unsuspected, undiagnosed infectious tuberculosis.5, 9
  • Most of the workers, as well as patients or inmates, who died of TB suffered from poorly functioning immune systems related to medical conditions such as HIV infections or AIDS, or to medical treatments such as cancer chemotherapy.10
  • Many health care, correctional facility, and other workers are at increased risk of tuberculosis for reasons unrelated to their work.14
  • Hospitals and correctional facilities reported increased implementation of tuberculosis control measures by the mid-1990s.15
  • Overall, the measures recommended by CDC for prevention of the transmission of TB in health care facilities have contributed to the ending of outbreaks of tuberculosis and the prevention of new outbreaks.16

The AHA remains committed to the health of our health care workers and believes that these gains must be extended to the areas of greatest need. Hospitals have put many important processes and systems into place over the past 10 or more years to sustain these improvements. In recent testimony provided to the IOM committee,(12) we referenced the high percentage of employee health programs in place in our hospitals, the increased attention to the environment, and the current efforts of hospitals to incorporate American Institute of Architects (AIA) guidelines or state regulatory engineering controls. For example, we are heartened that new requirements for an infection control risk assessment are in place and that new construction or major renovation of health care facilities requires negative airflow in triage and waiting areas of emergency rooms and radiology suites -- protecting health care workers, patients and visitors from individuals with unidentified TB disease. JCAHO requires enforcement of these same standards and reinforced attention to ventilation and engineering controls in their revised standards.

The AHA has on numerous occasions expressed concern with proposed OSHA requirements that go beyond the provisions of the CDC guidelines -- including OSHA requirements that would adopt measures that the CDC recommends be considered, but for which little scientific evidence exists to support their efficacy in reducing the risk of transmission. Hospitals have spent considerable time and resources since 1994 in developing TB control programs consistent with the 1994 CDC guidelines. Proposed OSHA requirements that go beyond these recommendations would place an additional and unneeded burden on all hospitals, especially on small and rural hospitals already struggling to maintain financial viability. OSHA should not impose any requirements beyond those recommended by the CDC unless there is scientific evidence of their efficacy in reducing risks to workers. We have consistently identified the most troublesome requirements as those pertaining to the risk assessment and skin testing. Clearly the IOM report and the peer reviewers agree with our concerns on these fronts.

In light of the comprehensive IOM report, as well as the reviews submitted by Menzies and Nicas, we think serious concerns have been raised regarding the foundation of the proposed standard. Given the current declining rates of TB disease, the lack of transmission in health care facilities, the current extent to which TB guidelines have been implemented in hospitals, and the inability to totally prevent TB exposure, the AHA questions whether the issuance of a final OSHA TB standard is justified.


The AHA recognizes and appreciates the attention that OSHA has given to ensuring that our health care workers are provided as safe an environment as possible. This effort, in concert with efforts from other agencies and professional organizations, has resulted in 45 percent decrease in incidence of TB in the US -- an unprecedented landmark.13 The AHA recommends that OSHA partner with public health, hospitals and others to assure continued advocacy for elimination of TB and to sustain the significant gains achieved. The result will be a rectification of past neglect of the public health infrastructure and support for the continuing success of a non-regulatory approach to conquering this disease.

Thank you for the opportunity to submit these comments. If you have questions, please do not hesitate to contact Roslyne Schulman, senior associate director for policy development, at (202) 626-2273 or at


Richard J. Pollack
Executive Vice President




Nicas, M. Review of Federal OSHA Tuberculosis Quantitative Risk Assessment. November 28, 2000. OSHA H371, Exhibit 186.


Menzies, R. Critical Review of TB Quantitative Risk Assessment. November 2000. OSHA H 371, Exhibit 185.


Basics of Tuberculosis. Tuberculosis in the Workplace, Field MJ (ed). National Academy Press (Washington DC) 2001; Chapter 2: 4-9.


The Tuberculin Skin Test. Bass, JB. Tuberculosis in the Workplace, Field MJ (ed). National Academy Press (Washington DC) 2001; Appendix B.


Occupational Risk of Tuberculosis. Tuberculosis in the Workplace, Field MJ (ed). National Academy Press (Washington DC) 2001; Chapter 5.


Implementation and Effects of CDC Guidelines. Tuberculosis in the Workplace, Field MJ (ed). National Academy Press (Washington DC) 2001; Chapter 6.


Occupational Tuberculosis Risk of Health Care Workers. Daniel TM. Tuberculosis in the Workplace, Field MJ (ed). National Academy Press (Washington DC) 2001; Appendix C.


Regulation and Future of Tuberculosis in the Workplace. Tuberculosis in the Workplace, Field MJ (ed). National Academy Press (Washington DC) 2001; Chapter 7.


Summary. Tuberculosis in the Workplace, Field MJ (ed). National Academy Press (Washington DC) 2001.


Introduction. Tuberculosis in the Workplace, Field MJ (Ed). National Academy Press (Washington DC) 2001; Introduction.


Occupational Safety and Health Administration, Health Standards Programs Draft Final Risk Assessment, August 2000. OSHA H371 Exhibit 184.


Testimony of the American Hospital Association before the Institute of Medicine Committee on Regulating Occupational Exposure to Tuberculosis, August 2000.


Progressing Toward Tuberculosis Elimination in Low-Incidence Areas of the United States: Recommendations of the Advisory Council for the Elimination of Tuberculosis: Reported Tuberculosis in the United States, 2000. MMWR; Vol. 51, No. RR-5; May 3, 2002.


Occupational Risk of Tuberculosis. Tuberculosis in the Workplace, Field MJ (ed). National Academy Press (Washington DC) 2001; Chapter 5:107.


Implementation and Effects of CDC Guidelines. Tuberculosis in the Workplace, Field MJ (ed). National Academy Press (Washington DC) 2001; Chapter 6:133.


Implementation and Effects of CDC Guidelines. Tuberculosis in the Workplace, Field MJ (ed). National Academy Press (Washington DC) 2001; Chapter 6:134.


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