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Regulations (Preambles to Final Rules) - Table of Contents
• Record Type: Occupational Exposure to Bloodborne Pathogens
• Section: 6
• Title: Section 6 - VI. Significance of Risk

VI. Significance of Risk

Section 6(b)(5) of the OSH Act vests authority in the Secretary of Labor to issue health standards. This section provides, in part, that:

The Secretary, in promulgating standards dealing with toxic materials or harmful physical agents under this subsection, shall set the standard which most adequately assures, to the extent feasible, on the basis of the best available evidence, that no employee will suffer material impairment of health or functional capacity even if such employee has regular exposure to the hazard dealt with by such standard for the period of his working life.

OSHA's overall analytical approach to making a determination that workplace exposure to certain hazardous conditions presents a significant risk of material impairment of health is a four-step process consistent with recent court interpretations of the OSH Act and rational, objective policy formulation. In the first step, a quantitative risk assessment is performed where possible and considered with other relevant information to determine whether the substance to be regulated poses a significant risk to workers. In the second step, OSHA considers which, if any, of the regulatory alternatives being considered will substantially reduce the risk. In the third step, OSHA examines the body of "best available evidence" on the effects of the substance to be regulated to set the most protective requirements that are both technologically and economically feasible. In the fourth and final step, OSHA considers the most cost-effective way to achieve the objective.

In the Benzene decision, the Supreme Court indicated when a reasonable person might consider the risk significant and take steps to decrease it. The Court stated:

It is the Agency's responsibility to determine in the first instance what it considers to be a "significant" risk. Some risks are plainly acceptable and others are plainly unacceptable. If, for example, the odds are one in a billion that a person will die from cancer by taking a drink of chlorinated water, the risk clearly could not be considered significant. On the other hand, if the odds are one in a thousand that regular inhalation of gasoline vapors that are 2% benzene will be fatal, a reasonable person might well consider the risk significant and take the appropriate steps to decrease or eliminate it. (I.U.D. v. A.P.I.), 448 U.S. at 655).

The Supreme Court's language indicates that the examples given were of excess risk over a lifetime. It speaks of "regular inhalation" which implies that it takes place over a substantial period of time and refers to the "odds. . . that a person will die," obviously a once in a lifetime occurrence.

The Court indicated that "while the Agency must support its findings that a certain level of risk exists with substantial evidence, we recognize that its determination that a particular level of risk is 'significant' will be based largely on policy considerations." The Court added that the significant risk determination required by the OSH act is "not a mathematical straitjacket" and that "OSHA is not required to support its findings with anything approaching scientific certainty." The Court ruled that "a reviewing court (is) to give OSHA some leeway where its findings must be made on the frontiers of scientific knowledge and that the Agency is free to use conservative assumptions in interpreting the data with respect to carcinogens, risking error on the side of overprotection rather than underprotection" (448 U.S. at 655, 656).

OSHA has used these guidelines provided by the Supreme Court in setting health standards for known carcinogens such as benzene and ethylene oxide as well as other substances such as cotton dust whose adverse health effects is not carcinogenic but is, none the less, very serious. For example, exposure to cotton dust can cause byssinosis.

As part of the overall significant risk determination, OSHA considers a number of factors. These include the type of risk presented, the quality of the underlying data, the reasonableness of the risk assessments, and the statistical significance of the findings.

The hazards presented by the transmission of bloodborne pathogens such as infection, illness and death, are very serious, as detailed above in the section on health effects. Hepatitis B infections cause acute and chronic disease. When an individual is infectious, either because of acute infection or because the individual has become a carrier, his or her blood and certain body fluids can transmit the virus to others. The hepatitis B infection places other members of the infectious individual's family at risk. If the patient has an acute infection, there is a 30% chance that a sexual partner will become infected. If the patient is a carrier the probability of transmission is much higher. Blood and certain other body fluids from the infected individual pose a risk to workers who may have contact as the result of occupational exposure. Perinatal transmission from an infected employee to her infant is an efficient mode of transmission with a particularly serious outcome. Symptoms of the disease can range from a flu-like illness to a more severe clinical illness characterized by jaundice, dark urine, nausea, vomiting, extreme fatigue, anorexia, abdominal pain, diarrhea, and sometimes joint pain, rash and fever. About 20% of jaundiced cases require hospitalization. Cases that do not require hospitalization often cause several weeks to months of work loss due to the disease symptoms reviewed above. Chronic HBV infection may result in frequent periods of illness, and continual, usually life-long, infectious status. In the most extreme cases of infection, death can result from fulminent hapatitis, viral cirrhosis of the liver or liver cancer (See Section IV.) HIV, the other major bloodborne pathogen, attacks the immune system, causing disease and death. Within a month following infection, the individual may experience an acute retroviral syndrome characterized by a mononucleosis-like syndrome. Later signs and symptoms can include persistent, generalized lymphadenopathy, myalgias, arthralgias, diarrhea, fatigue, rash, fever, and constitutional illness characterized by wasting syndrome which may lead to death. HIV infected individuals who have developed AIDS may develop neurologic, oncogenic or neoplastic problems as well as opportunistic infections. Common conditions include encephalopathy, dementia, myelopathy or peripheral neuropathy, Pneumocystis carinii pneumonia; Kaposi's sarcoma: candidiasis of the esophagus, trachea, bronchi or lungs; cytomegalovirus disease of an organ other than the liver, spleen or lymph nodes; as well as bacterial infections. The blood and certain body fluids from an infected individual present a risk of infection to others.

In this standard, OSHA has presented quantitative estimates of the lifetime risk of infection, clinical illness, and death from occupational exposure to HBV infected blood or other potentially infectious materials. Qualitative evidence of occupational transmission of HIV is also included in OSHA's risk assessment.

In preparing its quantitative risk assessment, the Agency began by considering whether some of the approximately five million occupationally exposed healthcare workers would be immune to hepatitis B because they had received the vaccine or because they had previously been infected with the virus. OSHA estimated that approximately two million of these individuals had received the hepatitis B vaccine. OSHA assumed a vaccination efficacy rate of 96% and calculated the number of employees who would develop immunity as the result of the vaccination. Based on information from the CDC, OSHA assumed that between 15 and 30 percent of healthcare workers had already been infected with hepatitis B virus, the vast majority of whom had been infected on the job, since only 3 to 6 percent of the general population has evidence of a previous infection. OSHA then added 96% of the vaccinated workers to the 15 to 30 per cent immune because of prior infection and subtracted that total from the population of healthcare workers. It is appropriate to subtract these workers because they will not be infected or reinfected with hepatitis B virus; their risk of acquiring a HBV infection approaches zero. This left a population of between 2.0 and 2.5 million. It is this group that constitutes the population at risk for hepatitis B infection.

OSHA estimates the risk of material impairment of health or functional capacity, that is, the lifetime occupational risk of infection from HBV to be from 83 to 113 cases per thousand with 21 to 30 cases of clinical hepatitis per thousand exposed workers who lack immunity. The estimated lifetime risk of death from HBV is 2 to 3 per one thousand exposed workers who are not previously immune. These estimates are based on the assumption of occupational exposure to HBV present in blood or other potentially infectious materials for the period of a working lifetime of 45 years. Moreover, OSHA's risk assessment shows that even if every exposed worker at risk were to receive the hepatitis B vaccine there would still be a remaining lifetime risk of material impairment of health of 3 to 5 per one thousand exposed workers based on the 96% efficacy of the vaccine. OSHA believes these estimates understate the risk; the actual risks attributable to occupational exposure to bloodborne diseases may be much higher for the following reasons: First, the true risk of HBV infection among the majority of the general population of U.S. adults is probably much lower than OSHA's estimate of the background risk since the majority of adults do not engage in the high risk behaviors associated with a large proportion of HBV infections. Thus, by overestimating the background risk, OSHA has probably underestimated the risk attributable to occupational exposure. Second, OSHA has assumed a 96% vaccine efficacy rate instead of 92.7% which is Merck, Sharp & Dohme's (Merck) estimate of vaccine efficacy adjusted for the age distribution of those covered by this standard. The Agency was unable to duplicate Merck's results and determine the accuracy of these figures since Merck did not provide the basic data and underlying methodology upon which the 92.7% estimate was based. By assuming 96% efficacy rate, OSHA may be underestimating the remaining risk to workers with occupational exposure.

However, factors such as changing prevalence of hepatitis B in the U.S. population, lack of data on non-healthcare workers, lack of data on differential risk by occupation and geographic location and assuming a 45-year working lifetime could cause the annual and lifetime HBV risk estimates to vary. OSHA estimated a lifetime occupational risk based on current information on U.S. population prevalence rates. Those prevalence rates may increase on decrease and will affect the lifetime risk estimates accordingly. Having specific quantitative data for non-healthcare workers and for particular occupations and locations would add more precision to the quantitative risk assessment, but that level of detail is not possible, given the data available in the record, nor necessary to a finding of significant risk, especially when the risk of infection is based upon occupational exposure to blood or other potentially infectious materials. The fact that not everyone would be exposed for exactly 45 years may mean less or more exposure incidents for a given individual over his or her lifetime, but would not affect a pooled risk estimate based on full time equivalents.

In the "benzene" decision, the Court wrote of deaths from carcinogens, but the Act requires the Agency to assure that no employee will suffer "material impairment of health or functional capacity." Obviously, material impairment includes not only death from HBV infection, but also serious illnesses or the development of permanent infectious status (HBV carrier). Moreover, OSHA has concluded that due to the number of possible outcomes following infection, the material impairment occurs when infection takes place regardless of the ultimate course of the disease. As noted above, in the case of severe infection, death can result from fulminant hepatitis, viral cirrhosis of the liver or liver cancer. In the case of chronic infection, the individual may experience frequent periods of illness, and continual, usually life-long, infectious status. An individual may remain infectious either because of acute infection or because he or she has become a carrier. This individual represents a pool from which the disease may spread to other family members or to the patient's sexual partner. Perinatal transmission from an infected employee to her infant is an efficient mode of transmission with a particularly serious outcome. Individuals who are infected as newborns have a 25% chance of dying from cirrhosis or PHC. They also remain infectious to others and can perpetuate the cycle of perinatal transmission.

HBV infection can result in very serious and debilitating illnesses. In most cases of clinical illness, symptoms of the disease will prevent the employee, for a period of time, from carrying out his or her routine daily activities often resulting in missed work days. In cases where the infected employee is hospitalized, the employee would be unable to work during the time he or she is hospitalized, and undoubtedly the out-of-work time would be longer as additional recovery time is invariably required following hospital discharge. Since symptoms typically last from several weeks to several months and, in the case of chronic hepatitis, several years, there can be considerable lost work time. Becoming a carrier is a material impairment of health even though the carrier may have no symptoms. This is because the carrier will remain infectious, probably for the rest of his or her life, and any person who is not immune to HBV who comes in contact with the carrier's blood or certain other body fluids will be at risk of becoming infected. Given the health hazards associated with HBV infection, it is OSHA's opinion that the material impairment of health occurs when an individual becomes infected with HBV. Moreover, OSHA's interpretation of material impairment of health is consistent with NIOSH/CDC's pre-hearing and post-hearing comments on the standard, (Exs. 298, p. 4; 20-634).

OSHA's risk estimates for HBV infection are comparable to other risks which OSHA has concluded are significant, and are substantially higher than the example presented by the Supreme Court.

Public response to the bloodborne pathogen rulemaking hearings indicated general agreement that the risk of contracting hepatitis B to workers with occupational exposure to blood or other potentially infectious materials is unacceptably high. Indeed, it was the testimony of many employers that they had already instituted or upgraded their infection control programs and were vaccinating their employees, indicating an acceptance by employers that employees who are not provided the protections that would be mandated by this standard are at risk of contracting HBV.

After thoroughly considering the magnitude of the risk as shown by the quantitative and qualitative data, OSHA concludes that the risk of death and material impairment of health resulting from acute and chronic HBV infection is significant, that HBV presents a significant risk to both unvaccinated employees and employees who have been vaccinated but have not developed immunity. Moreover, because HBV is not the only bloodborne pathogen capable of causing disease, all employees who are exposed to blood and other potentially infectious materials, whether they are HB-vaccinated or not, may be at risk of infection.

At this time, OSHA believes that there are not sufficient data on HIV to quantify the occupational risk of infection. Nevertheless, the epidemiological data on HIV provide strong qualitative evidence that HIV can be transmitted in the workplace and serve to further illustrate risk remaining after the major protection measure of HBV vaccination is implemented. Individuals who have a needlestick exposure to blood from an HIV infected individual have a 3 to 4 per 1,000 risk of developing an HIV infection.

OSHA's determination that employees who work in virus research and production facilities are at risk is supported by the report of one employee out of a population of less than 100 who were working with concentrated HIV who seroconverted. These employees are at risk because the virus is concentrated and is present in much higher titers than in blood, thus increasing the likelihood of the employee becoming infected following an exposure incident.

OSHA also concludes that the final bloodborne pathogen standard will result in a substantial reduction of significant risk. The risk of HBV infection is most efficiently and dramatically reduced by vaccinating all workers exposed to blood and other potentially infectious materials. Based on OSHA's estimate of lifetime occupational risk, vaccination of all workers would result in 2 to 3 fewer deaths per 1,000 workers exposed over a working lifetime. Further, vaccination would result in 80 to 108 fewer cases of material impairment of health due to HBV infection, and 20 to 28 fewer cases of clinical illnesses per 1,000 workers exposed over a working lifetime. Assuming 15% of the population at risk is immune to HBV because of prior infection, OSHA estimates that vaccinating the remainder and all of their replacement in the labor force will prevent approximately 270,000 infections, over 68,000 of which will result in clinical illness, including, in addition to cases of acute and chronic symptomatic illness, 27,000 HBV carriers and 6,000 deaths over 45 years. If 30% of the population at risk is immune, the number of infections prevented following vaccination of all employees is estimate to be approximately 244,000 including 61,000 cases of clinical illness, over 12,000 HBV carriers and more than 5,400 deaths over 45 years.

Despite these dramatic decreases in infections, OSHA estimates that 3 to 5 HBV infections would occur with one case of clinical hepatitis per 1,000 exposed workers who lack immunity over 45 years even if all exposed employees were to receive the hepatitis B vaccine. This is because the vaccine is effective for only 96% of the people to whom it is given. Moreover, in constructing TABLE V-8 in Section V: Quantitative Risk Assessment, OSHA assumed that all workers at risk will agree to be vaccinated. However, the record indicates that this has not been the case in the past and, although education of employees on the benefit of vaccination should increase acceptance, it is unlikely all workers will be willing to be vaccinated. For example, OSHA witnesses testified that some vaccination programs yielded between 90-100 percent acceptance rate when the employee was required to be vaccinated to work at the facility (Joseph H. Coggin, Ph.D., Tr., 9/12/89, pp. 56-58; James A. Cottone, M.S., Tr., 9/19/89, p. 56; Dr. L. L. Campbell, Tr., 9/19/89, p. 72; Dr. W. L. Sutker, Tr., 9/27/89, p. 14; Dr. J. A. Barnett, Tr., 9/27/89, p. 221). Other witnesses from OSHA and the public noted that their vaccination programs ranged between 25-55 percent compliance rates (Kathleen F. Gordon, M.S., Tr., 9/19/89, p. 9; James A. Cottone, M.S., Tr., 9/19/89, p. 56; Jill Witter, Esq., Tr., 9/18/89, p. 163; T. Ryan, Tr., 9/27/89, p. 293). According to two OSHA witnesses still other programs yielded between 10-25 percent participation in the vaccination program in part due to the lack of mandatory education, advocacy and follow-up procedures (James A. Cottone, M.S., Tr., 9/19/89, p. 56; Joseph H. Coggin, Ph.D., Tr., 9/12/89, pp. 56-58).

In general, compliance rates of various Hepatitis B vaccination programs implemented throughout the country varied from over 95 percent to below 10 percent. This clearly demonstrates that even in the presence of a well organized and supported vaccination program, not everyone is willing to accept the vaccine. A descriptive analysis of the reported compliance rates based on evidence in the record indicated that three fourths of the vaccination programs in existance reported compliance rates less than 75 percent. In addition, based on survey results, OSHA estimated the average acceptance rate of a vacciation program to be approximately 50 percent. Using this information, OSHA constructed a scenario where 50 percent of those offered the hepatitis B vaccine would actually agree to be vaccinated, and estimated the remaining lifetime occupational risk assuming a 96% vaccine efficacy. These numbers are found in TABLE V-9 in Section V: Quantitative Risk Assessment. Under the assumption of 50 percent compliance to a vaccination program and 96 percent efficacy rate, the remaining lifetime occupational risk is significant. A range of 44 to 59 HBV infections are expected to occur per one thousand exposed workers per working lifetime. This will result in 11 to 15 clinical illnesses and approximately one death per thousand exposed workers. In addition, OSHA's estimate of remaining risk is probably an underestimate of the number of HBV infections that are likely to occur because of the overestimation of the background risk and the assumption of a 96% efficacy rate instead of Merck's estimate of 92.7%. Moreover, the hepatitis B vaccine will not protect employees from other bloodborne pathogens such as HIV. Based on these data, OSHA has concluded that widespread administration of the hepatitis B vaccine will not eliminate significant risks.

Congress passed the Occupational Safety and Health Act of 1970 because of a determination that occupational safety and health risks were too high. Based on this, Congress gave OSHA authority to reduce risks of average or above average magnitude when feasible. It is clear that the risks associated with HBV infection are not insignificant. Without the implementation of the present standard, OSHA estimates the lifetime risk of infection from HBV to be from 83 to 113 cases per thousand with 21 to 30 cases of clinical hepatitis per thousand exposed workers. The lifetime risk of death from HBV is 2 to 3 per one thousand workers who lack prior immunity. OSHA estimates that the standard for bloodborne pathogens will reduce the risk of death and material impairment of health from 83 to 113 cases per thousand to 3 to 5 per 1000. The risk of death from HBV will be reduced to one death per ten thousand. Even when a more realistic scenario is considered, where the compliance rate to a vaccination program is 50 percent and the efficacy of the vaccine is still 96 percent, the remaining lifetime occupational risk remains significant. This scenario will result in an estimate of 43 to 59 HBV infections per thousand employees with 11 to 15 cases of clinical hepatitis and approximately one death per one thousand exposed workers.

The above estimated figures are comparable to other risk estimates judged significant by OSHA in previous health and safety rulemakings. Typical occupational risk of death (from all causes including accidents and illness) in occupations of average risk are 2.7 per 1,000 for all manufacturing and 1.62 per 1,000 for all service employment derived from 1979 and 1980 Bureau of Labor Statistics data for employers with 11 or more employees adjusted to 45 years of employment for 46 weeks per year. The lifetime risk of death associated with HBV, 2 to 3 per one thousand non-immune exposed worker is comparable to those stated above; even the risk of material impairment of health due to HBV infection is sufficiently high to prompt OSHA to protect the health of healthcare workers by implementing this standard.

In summary, OSHA estimates this standard for bloodborne pathogens will result in 2 fewer deaths, 80 to 108 fewer cases of HBV infection, and 20 to 28 fewer cases of clinical illnesses per 1,000 workers exposed over a working lifetime. As OSHA believes the standard for bloodborne pathogens will reduce risk of HBV infection and material impairment of health from 83 to 113 per thousand to 3 to 5 per 1000, the Agency is carrying out the Congressional intent and is not attempting to reduce insignificant risks.

OSHA estimates that vaccination of exposed workers alone would leave a remaining significant risk of HBV infection (3 to 5 or 43 to 59 per thousand exposed workers, depending on acceptance rates of the hepatitis B vaccine), OSHA has concluded that compliance with the standard as a whole, that is, compliance with all of the final provisions, including vaccination, engineering controls, work practices, protective equipment, housekeeping, and training, would reduce that significant risk substantially. After adjusting for background risk, OSHA has estimated between 5,814 and 6,645 cases of occupational exposure to Hepatitis B virus. Compliance with the standard is estimated to prevent between 5,058 and 5,781 cases of occupationally induced HBV infection per year, of which 1,265 to 1,445 would have resulted in acute symptoms, and 113 to 129 in death. In addition, between 3,077 and 3,325 estimated non-occupational induced cases of hepatitis B infection will be prevented due to the substantial elimination of background risk (non-occupational risk) for vaccinated workers and due to the reduced transmission of infection to sex partners of employees. In total, the final standard is expected to prevent between 8,383 and 8,858 infections and between 187 and 197 deaths annually. As previously stated, there are no sufficient data on HIV to quantify the occupational risk of infection; however, the above listed protective provisions of the standard will also reduce exposure to HIV infected body fluids and other materials thus reducing the risk of infection to HIV. In light of all of the above, OSHA concludes the entire standard is needed. This is consistent with the congressional intent and the Supreme Court rationale that OSHA is to reduce significant risks, which, in this case, would include risks remaining after administration of the hepatitis B vaccine. OSHA has considered various regulatory alternatives in addressing the risks of occupational exposure to bloodborne pathogens. These include informing employers and employees of the risk through the Joint Advisory Notice published in the Federal Register by the Department of Labor and the Department of Health and Human Services (52 FR 4181) and the institution of an enforcement program. The enforcement program has consisted of citing employers for violating Section 5(a)(1) of the OSH Act, the general duty clause (29 U.S.C. 654(a)(1)), and certain general industry standards. (For a brief explanation of OSHA's enforcement program, see OSHA Instruction CPL 2-2.44B and Section III: Events Leading to the Standard, below).

Although the current OSHA enforcement program has reduced the risks of occupational exposure to bloodborne pathogens to some extent, significant risks remain and it is the Agency's opinion that an occupational health standard promulgated under section 6(b) of the Act will much more effectively reduce these risks for the following reasons. First of all, because of the standard's specificity employers and employees are given more guidance in reducing exposure to bloodborne pathogens. Second, it is well known that a standard is more protective of employee health than an enforcement program that is based upon a general provision because the standard requires more abatement methods than those required by the general duty clause and the general industry standards. Third, the general duty clause and the cited general industry standards impose heavy litigation burdens on OSHA because OSHA must prove that a recognized hazard exists at a particular workplace. Since this standard specifies both the conditions which trigger the application of the standard and the abatement obligations, thereby assuming the existance of the hazard, no independent proof of the hazard in the particular workplace need be presented. The reduction in litigation burdens will mean that the Labor Department, as well as the employer, will save time and money in litigation cases. Finally, the promulgation of this standard will result in increased protection for employees in state-plans states because these states, although not required to adopt general duty clauses, must adopt standards at least as effective as Federal OSHA standards.

In summary, the Joint Advisory Notice and the institution of the enforcement program have been fruitful, but they have not eliminated the significant risks. Therefore OSHA has concluded that a standard specifically addressing the risks of bloodborne pathogens is necessary to further substantially reduce significant risks. OSHA's current data indicate the alternative selected is both technological and economically feasible. OSHA's analysis of technological and economic feasibility of the standard is discussed in the following section of the preamble.

[56 FR 64004, Dec. 6, 1991; 57 FR 29206, July 1, 1992]

Regulations (Preambles to Final Rules) - Table of Contents

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