Safety Issues

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Safety Issues



Personnel working with hazardous materials need safety guidelines for their personal protection and guidelines to prevent exposing those not working directly with these hazardous materials. Strict adherence to these guidelines is of particular importance for those working with microorganisms in order to control contamination and infection. To achieve these goals, it is essential to develop and have in place simple and direct protocols that are routinely reviewed, updated, and practiced. The key words are “current,” “awareness,” and “knowledgeable.” Three organizations that illustrate efforts to facilitate acceptable, rational guidelines for safety are the Occupational Safety and Health Administration (OSHA), the Centers for Disease Control and Prevention (CDC), and the World Health Organization (WHO).

OSHA was established in 1971 as a result of the Occupational Safety and Health Act of 1970. Its objective is to provide a safe workplace. The CDC was created in 1946 as a major operating component of the U.S. Department of Health and Human Services (HHS). It is the lead agency of the federal government charged with protecting the health and safety of all Americans as well as providing essential human services for those in need. The WHO grew from the HO (Health Organization), an agency of the League of Nations, and was established by the United Nations (UN) in 1948. It functions as a coordinating authority on international public health.


Because of the implementation of OSHA regulations after its establishment in 1971, workplace fatalities have decreased by more than 60% and injuries and sickness incidences on the job have declined by 40% while the workforce has increased from about 56 million to 115 million. The CDC, although initially charged to control malaria, since 1946 has led public health efforts in the prevention and control of infectious and chronic diseases, injuries, workplace hazards, disabilities, and environmental health emergencies. Its efforts are action oriented toward improving the quality of people’s daily lives and alerting them in response to health emergencies. The WHO, in fulfilling its task of combating infectious disease while promoting the general health of the peoples of the world, coordinates and monitors outbreaks such as severe acute respiratory syndrome (SARS), malaria, and AIDS in addition to developing and distributing vaccines. In 1979, the WHO declared the viral disease smallpox to be eradicated, with polio the next disease expected to be eradicated.


OSHA will continue to monitor the workplace to identify hazards to the health and safety of the public in the workplace environment. The CDC will continue to study and develop contingencies against outbreaks of disease through vaccines, development of new drugs, and implementation programs, while monitoring possible epidemics and pandemics. Evaluation of pandemic flu resources, traveler’s health, outbreaks of Escherichia coli, environmental health in general, emergency preparedness, and response to health and disease threats will continue to be at the forefront of their efforts. Additional local, national, and international agencies may be formed to meet needs for safety guidelines. Furthermore, the WHO has reversed its previous policy on the spraying of dichlorodiphenyltrichloroethane (DDT) to prevent the spread of malaria. This reversal has restored a useful tool in the fight against malaria.

Laboratory Safety

Work in any type of laboratory involves a variety of possible hazards that are not found in most workplaces and therefore special precautions are necessary in that type of environment. Although this textbook focuses on microbiology issues, a medical or clinical laboratory is an environment involved in testing of biological specimens to obtain information about the health of patients. In general, clinical laboratories deal with the following:

Other laboratory environments require strict regulations for safety as well. Workers in laboratory environments are surrounded by physical, chemical, and biological hazards that present the potential for accidents and injury. The Occupational Safety and Health Administration (OSHA), a division of the U.S. Department of Labor, provides regulations, specific standards, and guidelines that, if followed, ensure the safety of workers in the laboratory environment.


Starting in the early days of microbiological research, people working in the laboratories recognized that acquiring infections from the agents they manipulated and worked with represented an occupational hazard. Biological agents include bacteria, viruses, fungi, other microorganisms, and their toxins. Biological agents have the capability to adversely affect human health, ranging from mild allergic reactions to serious medical conditions, and even death.

The most commonly acquired laboratory infections are caused by bacteria. As microbiologists learned how to culture animal viruses, it became evident that there is a potential for becoming infected by these agents also, as exemplified by the laboratory studies on yellow fever among others.


The Miracle Cure: Soap and Water!

Throughout the first half of the nineteenth century the death rate for women in childbirth was high. Almost 25% of the women delivering their babies in hospitals and clinics were dying from a disease called “childbed fever” (puerperal sepsis) that was subsequently found to be caused by the bacterium Streptococcus pyogenes. In 1843, Dr. Oliver Wendell Holmes introduced the simple practice of proper hand washing as a primary means of preventing childbed fever. He believed and tried to convince the medical establishment at the time that the disease was in fact being passed on to pregnant women by the hands of their doctors. For the most part his ideas were viewed with skepticism and were rejected by many physicians at the time. In the late 1840s, Dr. Ignaz Semmelweis observed while working in a maternity ward in Vienna that the mortality rate among delivering mothers was much greater in patients treated by medical students than those treated by midwives. Semmelweis observed that the medical students were going from classes in the autopsy room to the delivery ward without washing their hands. When the students were ordered to wash their hands with a chlorine solution before touching the patients in the delivery process the mortality rate eventually dropped to less than 1%! Even after these results, the medical community still did not widely accept the importance of this simple procedure. It wasn’t until the late 1800s and early 1900s that the support of people like Pasteur and Dr. Josephine Baker convinced the medical profession and the public as a whole that the simple act of hand washing was (and still is) one of the best tools available for preventing/controlling the spread of disease.

Guidelines and standards for the protection of personnel working in microbiological laboratories evolved on the basis of data and the understanding of the risks associated with various manipulations of virulent agents transmissible by different routes. These guidelines for protection include a combination of engineering controls, management policies, work practices and procedures, and medical interventions if necessary with records of compliance and updates noted. The simplest, yet most effective method of control to prevent the spread of infectious diseases is the proper washing of hands. Hand hygiene guidelines were developed by the CDC’s Healthcare Infection Control Practices Advisory Committee (HICPAC) together with the Society for Healthcare Epidemiology of America (SHEA), the Association of Professionals in Infection Control and Epidemiology (APIC), and the Infectious Disease Society of America (IDSA). In summary, the hand hygiene guidelines are a major part of the overall CDC strategy to reduce the spread of infections, especially in the healthcare settings.

In 1992, OSHA published a rule that deals with the occupational health risk caused by exposure to human blood and other potentially infectious materials. A Biosafety Program was developed as an information management system to provide a process and tools to assess the safety, needs, and precautions in the planning, initiation, and termination of activities involving biological materials. The program is intended to protect personnel from exposure to infectious agents and to comply with federal, state, and local requirements. At present the program includes four major components (Box 5.1):

Different biosafety levels were developed for microbiological and medical laboratories for personal and environmental protection. Specifically, four levels of containment have been defined and these are termed biosafety levels (BSL-1 to BSL-4), depending on the agent to be handled. The National Institutes of Health (NIH) has introduced the concept of “risk groups,” in which agents are classified into four risk groups (RGs) on the basis of their relative pathogenicity (Table 5.1). The description of biosafety levels and procedures are presented as introductions and are not intended to be an in-depth treatise. In addition, they are being continuously updated by the NIH, and the NIH websites should be consulted for the most recent information (


Summary of Recommended Biosafety Levels for Infectious Agents

Risk Group 1 (RG1) Agents not associated with disease in healthy adult humans
Risk Group 2 (RG2) Agents associated with human disease but generally not serious and for which preventive and therapeutic interventions are available
Risk Group 3 (RG3) Agents associated with serious or lethal human disease. Preventive or therapeutic interventions may be available
Risk Group 4 (RG4) Agents likely to cause serious or lethal human disease. Preventive or therapeutic interventions are not usually available

Biosafety Level 1 (BSL-1)

BSL-1 applies to working with microorganisms that are generally not disease causing in healthy humans and therefore are of minimal potential hazard to laboratory personnel and the environment (Box 5.2). This safety level is used in municipal water-testing laboratories, high school laboratories, and in some community colleges teaching introductory microbiology classes with organisms that are not considered to be pathogenic and/or hazardous. These laboratories typically include a sink for hand washing, benchtops, sturdy furniture, windows with fly screens if they can be opened, and readily available disinfectants and antiseptics. The laboratory should be easily cleaned, decontaminated, and have procedures posted for the safe disposal of materials being used.

The laboratory at this safety level does not have to be isolated from other parts of the building; however, a door that can be closed while work with agents is in progress is highly desirable. Hazard warning signs (Figure 5.1) should be posted on doors, indicating any hazards that may be present. A sink for hand washing needs to be available because hand washing is one of the simplest yet most important procedures used by laboratory personnel to remove unwanted microbial agents or chemicals used in the laboratory.

Standard microbiological practices at BSL-1 include the use of mechanical pipetting devices and prohibition of eating, drinking, and smoking. People working in the laboratory should be wearing laboratory coats and gloves when working with biological agents. Adequate, efficient methods and procedures for disposal of materials used are also established.

The laboratory supervisor of a BSL-1 laboratory needs to have general training in microbiology or a related science and is responsible for establishing the general laboratory safety procedures, for training laboratory personnel, and for the updating of these procedures.

Biosafety Level 2 (BSL-2)

BSL-2 is similar to BSL-1 regarding the agents that are being handled. However, for BSL-2 work, the facility, containment devices, administrative controls, practices and procedural standards, and guidelines are designed to maximize safe working conditions for laboratories working with agents of moderate risk to personnel and the environment. Agents manipulated at BSL-2 are considered a moderate risk. They often include pathogens to which personnel have previously been exposed and to which they have had an immune response (e.g., childhood diseases) or against which they have received immunization (Box 5.3). Immunization is recommended before working with certain agents, for example, immunization against the hepatitis B virus which is recommended by OSHA for people at high risk of exposure to blood and blood products. In addition to procedures established in the BSL-1 level laboratory, the BSL-2 laboratory requires that:

Biosafety Level 3 (BSL-3)

BSL-3 applies to clinical, diagnostic, teaching, research, or production laboratories using original or exotic agents (Box 5.4). Such agents can potentially cause serious disease or even lethality if exposure occurs. In addition to the laboratory procedures described in BSL-1 and BSL-2, laboratory personnel require specific training in handling pathogenic and potentially lethal agents with on-site supervision by scientists experienced and qualified in working with such agents. Many additional standards are necessary to qualify as a BSL-3 laboratory. Some of the additional procedures include but are not limited to: