APPENDIX D— 33 
procedures found under special headings, 
such as decontamination, disposal, and ani- 
mal care, are, in reality, specific Instructions 
for safely accomplishing otherwise routine 
housekeeping chores. In these safety sug- 
gestions for research on recombinant DNA 
molecules, it has been elected to address 
specifically only tasks of a Janitorial nature 
under the subject of housekeeping. 
The objectives of housekeeping in the bio- 
logical laboratory arp to: 
1. Provide an orderly work area conducive 
to the accomplishment of the research pro- 
gram. 
2. Provide work areas devoid of physical 
hazards. 
3. Provide a clean work area with back- 
ground contamination ideally held to a zero 
level but more realistically to a level such 
that extraordinary measures in sterile tech- 
niques are not required to maintain Integrity 
of the biological systems being researched. 
4. Prevent the accumulation of materials 
from current and past experiments that con- 
stitute a hazard to laboratory personnel. 
5. Prevent the creation of aerosols of haz- 
ardous materials as a result of the house- 
keeping procedures used. 
Procedures developed In the area of house- 
keeping should be based on the highest level 
of risk to which the personnel and Integrity 
of the experiments will be subject. Such an 
approach avoids the confusion of multiple 
practices and retraining of personnel. The 
primary function, then, of routine house- 
keeping procedures Is to jjrevent the ac- 
cumulation of organic debris that (1) may 
harbor microorganisms that are a potential 
threat to the integrity of the biological sys- 
tems under Investigation, (11) may enhance 
the survival of microorganisms inadvert- 
ently released In experimental procedures, 
(ill) may retard penetration of decontamin- 
ants. (Iv) may be transferable from one 
area to another on clothing and shoes, (v) 
may, with sufflcent buildup, become a bio- 
hazard as a consequence of secondary aero- 
sollzatlon by personnel and air movement, 
and (vl) may cause allergenic sensitization 
of personnel, e.g., to animal danders. 
Housekeeping In animal care units has 
the same primary function as that stated 
for the laboratory and should. In addition, 
be as meticulously carried out in quarantine 
and conditioning areas as In areas used to 
house experimentally Infected animals. No 
other areas In the laboratory have the con- 
stant potential for creation of significant 
quantities of contaminated organl 9 _ debris 
than do animal care facilities. 
In all laboratories, efforts to achieve total 
decontamination and to conduct a major 
cleanup of the biological complex are nor- 
mally undertaken at relatively long time 
Intervals. Routine housekeeping must be 
relied on to provide a work area free of sig- 
nificant sources of background contamina- 
tion. The provision of such a work area is 
not simply a matter of Indicating In a gen- 
eral way what htis to be done, who will do 
It, and how often. The supervisor must view 
each task critically In terms of the poten- 
tial biohazard Involved, decide on a detailed 
procedure for Its accomplishment, and pro- 
vide Instructions to laboratory personnel In a 
manner that minimizes the opportunity for 
misunderstanding . 
The following checklist outlines a portion 
of the Items requiring critical review by the 
laboratory supervisor. It Is not Intended to 
be complete but Is presented as an example 
of the detailed manner In which housekeep- 
ing In the biological laboratory complex 
must be viewed. 
Administration Areas 
Aisles 
Animal Food Storage 
Animal Bedding Storage 
Biological Safety Cabinets 
Bench Tops and Other Work Surfaces 
Ceilings 
Change Rooms 
Cleaning Solution Disposal 
Cages and Cage Racks 
Dry Ice Chests 
Deep Freeze Chests 
Entry and Exit Ways 
Equipment Storage 
Floors 
Glassware 
General Laboratory Equipment Cleanup 
Hallways 
Incubators 
Instruments 
Insect and Rodent Control 
Light Fixtures 
Mechanical Equipment Areas 
Mops 
Pipes — Wall and Celling Hung 
Refrigerators 
Showers 
Supply Storage 
UV Lamps 
Vacuum Cleaners 
Waste Accumulations 
Waste Water Disposal 
Others 
Housekeeping In the laboratory Is one of 
the avenues that leads to accomplishing the 
research program safely. It Is Important that 
housekeeping tasks be assigned to personnel 
who are knowledgeable of the research pro- 
gram and special hazards of the research 
environment. The recommended approach 
to housekeeping Is the assignment of house- 
keeping tasks to the research teams on an 
individual basis for their Immediate work 
areas and on a cooperative basis for areas 
of common usage. Similarly, animal care- 
taker personnel should be responsible for 
housekeeping in animal care areas. The labo- 
ratory supervisor must determine the 
frequency with which the Individual and 
cooperative housekeeping chores need be ac- 
complished. He should provide schedules and 
perform frequent Inspection to assure com- 
pliance. This approach assures that research 
work flow patterns will not be Interrupted by 
an alien cleanup crew, delicate laboratory 
equipment will be handled only by those 
most knowledgeable of Its particular require- 
ments, and the location of concentrated bio- 
logical preparations and contaminated equip- 
ment used In their preparation and appllca 
tion will be known. 
B. Floor Care 
Avoidance of dry sweeping and dusting will 
reduce the formation of nonspecific environ- 
mental aerosols. Wet mopping or vacuum 
cleaning with a hlgh-efficlency particulate air 
(HEPA) filter on the exhaust Is recom- 
mended. 
Careful consideration must be given to de- 
sign and quality In the selection of cleaning 
equipment and materials and In their use 
to prevent the substitution of one hazard for 
another. 
In the absence of overt hazardous spills, 
the cleaning process commonly will consist 
of an Initial vacuuming to remove all gross 
particulate matter and a follow-up wet mop- 
ping with a solution of chemical decontami- 
nant containing a detergent. Depending on 
the nature of the surfaces to be cleaned and 
availability of floor drains, removal of resid- 
ual cleaning solutions can be accomplished 
by a number of methods. Among these are: 
pickup with a partially dry mop, pickup with 
a wet vacuum that has an adequately filtered 
exhaust, or removal to a convenient floor 
drain by use of a floor squeegee. 
After cleaning up a spill of Infected ma- 
terial, the residual solution should not be 
discharged to a sanitary sewer until it has 
been autoclaved or given further chemical 
treatment, such as by the addition of sodium 
hypochlorite sufficient to provide a final con- 
centration of 600 ppm chlorine. Most house- 
hold bleaches are marketed with a chlorine 
content of 5.25%. These In a final dilution 
of 1:100, yield 625 ppm of available chlorine. 
After allowing a contact time of 15 minutes, 
these solutions may be flushed down any 
available drain. Chlorine solutions In these 
high concentrations may be too corrosive for 
general application to floors and equipment. 
In any event. If solutions are used In this 
way, after the contact time the area should 
be rinsed with water. 
While it is recommended that dry sweeping 
be minimized, this may be the only method 
available or practicable under certain cir- 
cumstances. In such cases, sweeping com- 
pounds used with push brooms and dry-dust 
mop heads treated to suppress aerosolizatlon 
of dust should be used. 
Sweeping compounds available from the 
usual Janitorial supply firms fall in three 
categories : 
Wax-based compounds used on vinyl floors 
and waxed floor coverings. 
Oil-based compounds for concrete floors. 
Oil-based compounds with abrasives (such 
as sand) to achieve a dry scouring action 
where much soil Is present. 
Dry-dust mop heads can be purchased as 
treated disposable units or as reusable, 
washable heads that must be treated with 
appropriate sprays or by other means to Im- 
prove their dust-capturing property. 
D. Vacuum Cleaning 
In the absence of a HEPA filter on the 
exhaust, the usual wet and dry industrial- 
type vacuum cleaner Is a potent aerosol gen- 
erator. The HEPA-filtered exhaust used In 
conjunction with a well-sealed vacuum unit, 
however, can negate this factor because of Its 
ability to pass large volumes of exhaust air 
while retaining particles with a minimum 
efficiency of 99.97%. Wet and dry units In- 
corporating a HEPA filter on the exhaust 
are available from a number of manufac- 
turers. 
There are no particular requirements with 
respect to the manner In which the dry 
vacuuming Is accomplished other than to J 
emphasize that the objective Is to remove all 
debris and particulate matter. The manu- 
facturer’s directions adequately detail the 
frequency of bag changes, filter changes, 
and mechanical adjustments. 
Dry material vacuum-collected during 
these floor-cleaning activities Is potentially 
contaminated, but the nature of the risk 
Is probably greater to the experiment than ( 
to the experimenter. It Is wise to effect bag | 
and filter changes and to clean out collec- j 
tion tanks In a manner that will avoid or ' 
minimize aerosolizing the contents of the i 
vacuum cleaner. | 
A vacuum machine that collects debris In ; 
a disposable bag Is preferable to machines ^ 
that collect the major debris In a tank and 
on an exposed primary filter. Even though ? 
It may serve as a primary filter, the dlspos- E 
able bag must be removed with caution. A ^ 
bellows effect may pump dust out of the bag j 
If Its Intake opening Is not sealed before I 
moving It to a plastic bag for transfer out | 
of the area. In any event, the outer surface of 1 
the disp>osable bag will probably bear some 
dust contamination, which also may occur I 
on inner surfaces of the machine. ^ 
To avoid contaminating experimental ma- j 
terials, the emptying of vacuum collection , 
tanks and changing of bags and filters are ‘ 
best done away from the Immediate labora- 
tory area, for example. In a small area that 
can be easily cleaned afterwards. The use 
of heavy rubber gloves Is recommended when 
C. Dry Sweeping 
