6. Assessing the Risks
When discussing the risks associated with biological research, four main points must be considered:
- the hazards imposed by the microorganism or by the biological process on the people performing it - what risks are they taking in getting infected or contracting a disease?
- the risk imposed by the process on the environment, the possibility of an unwanted leak from any stage of the process, resulting in an uncontrolled release of a pathogen or a toxic product to the environment.
- the risk created by the biosystem or the product by the environment: what are the chances that the whole process will become contaminated, or will change its established course with the possibility of no end product or worse, with an unwanted product?
- the risks created for the environment by the deliberate release of biological agents, the impact of which is very difficult to foresee.
6.1 The Agent
Wedum and Kruse (Wedum, A.G. and Kruse, R.H. 1969. Assessment of risk of human infection in the microbiology laboratory. Misc Pub 30, Industrial Health and Safety Directorate, Fort Detrick, Frederick , Md.) developed an approach for estimating risk the of infection, as a working guide for laboratories. They considered certain variables dependent on the agent:
- the occurrence of recorded laboratory infections
- the minimal human infectious dose
- the recovery of microorganisms from the urine and feces of infected animals
- the frequency of cage-mate infection
Other considerations associated with the infectious agent are: the severity of the disease (mild, disabling, fatal), whether there is person-to-person transmission, and the geographical distribution of the agent. All these variables were considered by several institutions and international organizations, and etiologic agents were classified on the basis of hazard into four groups, with recommendations for the conditions under which each group (class) should be handled. (See tables).
Risk group (Biohazard class) definition:
- Risk group 1: Agents not known to cause disease in healthy adults.
- Risk group 2: Agents of moderate potentional hazard, associated with human disease hazard (auto-inoculation, ingestion, mucous membrane exposure).
- Risk group 3: Indigenous or exotic agents with potential for aerosol transmission; disease may have lethal serious consequences.
- Risk group 4: Dangerous/exotic agents which pose high risk of life-threatening disease; aerosol-transmitted lab infections; or related agents with unknown risk of transmission.
6.2 The Worker
The variables to be considered when assessing the risk of infection to the worker are those factors affecting susceptibility and resistance:
Other human factors to consider in assessing risk are the age and sex of the workers and their level of training and skill.
- the immunization of the worker to the agent
- the availability of a vaccine
- therapy including medication, antiserum, and interferon
- the worker's state of immunosupression as a result of disease, steroids, or cytotoxic medications
The hazard caused by certain microorganisms to the human fetus has been established in many cases (rubella, etc.), but is still unknown for others. Thus, it is advisable that pregnant women should not work with infections viruses or tissue cultures during the first trimester. For further information, contact the Consulting Center for Pregnant Women, at 02-675-8430 or 02-675-7453.
6.3 The Process
Usually, experiments that involve laboratory animals have higher hazard levels than those performed in vitro. Many variables beyond the control of the worker are present when working with animals, while with in-vitro work every step can be controlled and calculated.
Usually after the research and development stages, the biotechnological processes use large volumes of microorganisms in high concentrations. These two variables (volume and concentration), when taken into consideration in risk assessment, dictate a higher level of biosafety than the ones used for the same agents in small-scale research.
Freeze-drying (lyophilization) is a common process in biotechnology, and lyophilized cultures may be more hazardous than liquid ones because powder tends to disseminate freely for long distances by air movement. Any procedure that can generate aerosols must be assessed for risk, not only the obvious procedures like blending and centrifuging, but also the simple ones like pipetting, and pouring.