APPENDIX A 
14. CDC CLASSIFICATION OF ETIOLOGIC AGENTS ON THE BASIS 
OF HAZARD: A system for evaluating the hazards associated 
with various etiologic agents, and definition of minimal safety 
conditions for their management in microbiological investigations. 
The basis for Agent Classification is as follows: 
CLASS 1: Agents of no or minimal hazard under ordinary conditions 
of handling. 
CLASS 2: Agents of ordinary potential hazard. This class includes 
agents which may produce disease of varying degrees of severity 
from accidental inoculation or injection or other means of cuta- 
neous penetration but which are contained by ordinary laboratory 
techniques. 
CLASS 3: Agents involving special hazard or agents derived from 
outside the United States which require a federal permit for 
importation unless they are specified for higher classification. This 
class includes pathogens which require special conditions for contain- 
ment. 
CLASS 4: Agents that require the most stringent conditions for 
their containment because they are extremely hazardous to 
laboratory personnel or may cause serious epidemic disease. This 
class includes Class 3 agents from outside the United States when 
they are employed in entomological experiments or when other 
entomological experiments are conducted in the same laboratory 
area. 
CLASS 5: Foreign animal pathogens that are excluded from the United 
States by law or whose entry is restricted by USDA administrative 
policy. 
NOTE: Federally licensed vaccines containing live bacteria or 
viruses are not subject to these classifications. These classifica- 
tions are applicable, however, to cultures of the strains used for 
vaccine production, or further passages of the vaccine strains. 
15. CLASS I BIOLOGICAL SAFETY CABINET: A ventilated cabinet 
for personnel protection only, having ah open front with inward 
flow of air away from the operator. The cabinet exhaust air 
is filtered through a high -efficiency particulate air (HEPA) filter 
before being discharged to the outside atmosphere. This cabinet 
can be used for work with low- to moderate -hazard risk agents 
where no product protection is required. 
16. CLASS II BIOLOGICAL SAFETY CABINET: An open-front cabinet 
for personnel and product protection with mass recirculated airflow 
with HEPA-filtered exhaust and HEPA-filtered recirculated air. 
This cabinet can be used for work with low- to moderate-hazard 
Appendix A — 2 
