2. LABELING OF MICROBIAL RISKS

 

This case study is taken from an article I co-authored in the Journal of College Science Teaching. You can use this article as a pattern for the final paper. As you read through it, be prepared to discuss the following questions:

1. What are the four biosafety levels?

2. What are the advantages and disadvantages of the current system?

3. How well did the respondents perform?

4. Did the respondents show limited expertise?

5. Is there a cost to overestimating the risk?

6. What information should agencies provide on biosafety?

7. What are the competing interests in this case?

8. Using Chapter 8, how can we improve risk labeling in this case?

 

Introduction

The Centers for Disease Control (CDC) and National Institutes of Health (NIH) classify microorganisms into four biosafety levels based on their known hazards and recommended safety precautions (CDC 1988, NIH 1978). The World Health Organization (WHO) publishes a similar system based on the CDC-NIH guidelines (WHO 1979). These guidelines are recognized by public health agencies worldwide, and they have been available for more than 20 years (CDC 1988).

Despite these publications, the biosafety classification system is not readily available outside public health agencies. For example, these guidelines cannot be found in most microbiology textbooks. Even when available, the guidelines often lack the risk information needed to address many critical issues. In particular, increases in immune-compromised individuals over the last decade have been accompanied by increases in identified opportunistic pathogens (Rippon 1987). Most of the major studies on laboratory acquired infections were published before 1980 (Pike 1976, 1978, 1979) and therefore may be outdated (Vesley and Hartmann 1988). Also, exposures are probably rising due to increased microbial applications in the classroom as well as in industry (Liberman et al. 1991).

Within this context, how well do educators use the biosafety classification system? In an age of increased susceptibility, this information is vital to decision making. This question also has important policy implications for biological supply companies, professional organizations, government agencies, and health professionals.

 

METHODS

We designed a questionnaire to test the use of the CDC-NIH classification system. The questionnaire introduced the four biosafety levels and four levels of precaution (see Figure 1). Participants were then asked to use these guidelines to evaluate 15 commonly known microbial species (see Figure 2).

The questionnaires were mailed to 309 biology instructors at 49 California community colleges. Some of these instructors were directly involved in microbiology courses, while others were involved in biology survey courses. Given the use of microorganisms in non-microbiology courses, and given the broad application of these labels in educational settings, we decided that a range of biology instructors was appropriate for this questionnaire.

 

RESULTS

179 instructors completed the questionnaires (a response rate of 56%). The mean score of the respondents for identifying the correct biosafety levels was 30%. The corresponding mean score for proper precautions was 32%. A breakdown of scores by category is given in Table 1.

Closer examination shows a tendency to overestimate risks for each agent -- sign tests proved these differences statistically significant for all but two agents (see Table 2). While these results suggest safe practices by instructors, it also suggests limited understanding of the actual risk message. Moreover, it is alarming to see cases where many subjects underestimated the risks (the fungus C. immitis is a particularly dramatic example).

 

DISCUSSION

It is tempting to draw conclusions on the expertise of the responding instructors. However, we emphasize this was not a test of instructor qualifications. Moreover, the tendency to overestimate risks suggests a major concern for safety. However, the low scores do confirm our suspicions that most educators are not fully aware of this classification system. If the system were readily available, we would expect perfect scores. Furthermore, while we restricted our audience to California community college biology instructors, we have no evidence that such scores would be significantly better in other regions or other types of educational institutions.

While the results suggest that safety is preserved, there is a cost to overestimating risk. For example, higher levelprecautions for some microbial agents will require additional equipment (e.g., a safety cabinet). Fortunately, we doubt that most community colleges use the more hazardous microbes listed in our questionnaire. However, we also doubt that every laboratory exercises all the standard microbiological practices required for class 1 and class 2 microorganisms.

Consequently, we recommend the following actions to improve communication about microbial risks.

1) Immune-compromised individuals should seek out information on microbial risks before engaging in classroom laboratory work. This should include information on biosafety levels and proper precautions. If information is market driven, then this population should be the most concerned and active consumers. 2) Biological supply companies should provide complete and current information on microbial risks. If more instructors requested this information, perhaps more supply companies would routinely provide it. Ideally, supply companies should follow guidelines required for chemicals in material safety data sheets (MSDS). However, such actions may not come about voluntarily and may require legislation.

3) Professional organizations should act as advocacy groups for legislation that requires more widespread information on biosafety levels and microbial risks. Science teachers and health professionals should assist in educating the public on this classification system.

Finally, agencies should provide more complete information on biosafety levels. This should include the following items.

1) Risk assessment methods used to determine biosafety levels should be provided. This could be done through in-house agency research, or by requiring such information from biological suppliers.

2) Additional information should be available on individual microorganisms and their biosafety levels. For example, most microbial species are not listed in the CDC-NIH guidelines and, by definition, are assigned to biosafety level 1. However, there is significant variation among these organisms.

3) Morbidity and mortality information for opportunistic pathogens should be readily available. The classification of these microbial levels in biosafety level 1 ("agents of no or minimal potential hazards") can be misleading since some microbes, such as E._coli, cause countless infections while others show no evidence of inducing human disease. By providing more information on the history of these organisms, instructors and students can make more informed decisions.

4) Additional information should be provided on the use of microorganisms by special populations such asimmune-compromised individuals and students in educational laboratories.

5) The CDC-NIH should require reporting of laboratory acquired infections. While such records would be incomplete, they would be a significant improvement over the outdated information we now have.

Given the existing literature, it is reasonable to expect that a large population of students are increasingly susceptible to laboratory acquired infections. The first line of defense should be appropriate warnings to both students and teachers. This article shows there is much room for improvement.

 

REFERENCES

Centers for Disease Control. 1988. Biosafety in Microbiologicaland Biomedical Laboratories, 2nd edition, U.S. Department of Health and Human Services, Public Health Service.

Liberman, D.F., Israeli E. and R. Fine. 1991. Risk Assessment of biological hazards in the biotechnology industry. In: Occupational Medicine: State of the Art Reviews, vol. 6. Philadelphia. Hanley and Belfus, Inc.

National Institutes of Health (Office of Research Safety, National Cancer Institute, and the Special Committee of Safety and Health Experts). 1978. Laboratory Safety Monograph: A Supplement of the NIH Guidelines for Recombinant DNA Research. Bethesda, MD.

Pike,R.M. 1976. Laboratory Associated Infections: Summary and analysis of 3921 cases. Health Lab Sci 13:105-114.

Pike,R.M. 1978. Past and Present Hazards of working with infectious agents. Arch Pathol Lab Med 102:333-336.

Pike,R.M. 1979. Laboratory associated infections: incidence, fatalities, causes and prevention. Ann Rev Microbiol 33:41-66.

Rippon,J. 1987. The New Opportunistic Fungal Infection: diagnosis, isolation, identification, and impact on mycology, fear of fungi: Symposium of Medical Mycology. Mycopathologia 99:143-146.

Vesley,D. and H.M. Hartmann. 1988. Laboratory-Acquired Infections and Injuries in Clinical Laboratories: A 1986 Survey. American Journal of Public Health 78(9):1213-1215.

World Health Organization. 1979. Safety Measures in Microbiology: Minimum Standards of Laboratory Safety, WHO Weekly Epidemiological Record 44:340-342.

 

 

Figure 1. Biosafety Levels and Corresponding Precautions

Biosafety Levels	Precautions
I. Agent of no known or minimal potential hazard	A. No special precautions/ open bench
II. Agent of moderate potential hazard	B. Open bench / safety cabinet for aerosol creation
III. Agent which may cause serious or potentially lethal disease	C. Safety cabinet at all times
IV. Agent which poses a high individual risk of life threatening disease	D. Maximum containment laboratory with safety cabinets and personal protection

 

Figure 2. Microbes Included in Questionnaire

(Correct answers are given)

Bacteria	Biosafety Levels	Precautions
Bacillus subtilis	1	A
Escherichia coli	1	A
Staphylococcus aureus	2	B
Pseudomonas (GEM)	1	A
Mycobacterium tuberculosis	3	C

 

Viruses	Biosafety Levels	Precautions
T4 Bacteriophage	1	A
Epstein-Barr	1	A
Rabies	2	B
Hepatitis non-A,non-B	2	B
HIV	3	C

Fungi	Biosafety Levels	Precautions
Saccharomyces cerevisiae	1	A
Rhizopus stolonifer	1	A
Candida albicans	1	A
Coccidioides immitis	3	C
Cryptococcus neoformans	2	B

 

 

Table 1. Scoring of Questionnaires

(Correct Answers)

Category	# of questions	Mean	Standard deviation	% correct
Biosafety	15	4.9	2.3	33%
Precautions	15	4.7	2.8	31%
Bacteria	10	3.9	2.4	39%
Viruses	10	1.7	1.3	17%
Fungi	10	3.9	2.2	40%

 

 

Table 2. Sign tests For Instructor Responses 

(compared with correct levels)

biosafety levels:

precautions:

Bacteria:	low	high	p-value	low	high	p-value
B. subtilis	0	28	<.01	0	36	<.01
E. coli	0	87	<.01	0	61	<.01
S. aureus	4	70	<.01	27	41	.11
Pseudomonas (GEM)	0	61	<.01	0	63	<.01
M. tuberculosis	5	57	<.01	5	62	<.01

   

biosafety levels:

precautions:

Viruses:	low	high	p-value	low	high	p-value
T4 Bacteriophage	0	15	<.01	0	15	<.01
Epstein-Barr	0	117	<.01	0	117	<.01
Rabies	0	124	<.01	0	124	<.01
Hepatitis non-A,non-B	2	113	<.01	2	113	<.01
HIV	0	123	<.01	0	123	<.01

 

biosafety levels:

precautions:

Fungi	low	high	p-value	low	high	p-value
S. cerevisiae	0	12	<.01	0	12	<.01
R. stolonifer	0	16	<.01	0	16	<.01
C. albicans	0	108	<.01	0	108	<.01
C. immitis	15	24	.20	15	24	.20
C. neoformans	7	64	<.01	7	64	<.01