APPENDIX D— 28 
have as high explosive in an autoclave (5). 
Large-scale zonal centrifugation requires 
special attention (11) . 
F. Blenders, Ultrasonic Disintegrators, Col- 
loid Mills, Ball Mills, Jet Mills, Grinders, 
Mortar and Pestle. 
All these devices release considerable aero- 
sols during their operation. For maximum 
protection to the operator during the blend- 
ing of infectious materials, the following 
practices should be observed: 
1. Operate blending and cell -disruption 
and grinding equipment in a Biological Safe- 
ty Cabinet (9) . 
2. Use safety blenders designed to prevent 
leakage from the rotor bearing at the bottom 
of the bowl (9) . 
3. In the absence of a leak-proof rotor, in- 
spect the rotor bearing at the bottom of the 
blender bowl for leakage prior to operation. 
Test It in a preliminary run with sterile 
saline or methylene blue solution prior to use 
with infected material (9) . 
4. Sterilize the device and residual in- 
fectious contents promptly after vise. Use a 
towel moistened with disinfectant over the 
top of the blender (9) . 
5. Glass blender bowls are undesirable for 
use with infectious material because of po- 
tential breakage. If used, they should be 
covered with a polypropylene jar to prevent 
dispersal of glass (8). 
6. A new machine, the Col worth Stomacker 
(England) , in which material is homogenized 
in a plastic bag in a closed container, would 
appear to be safer than some of the other 
blenders (8). 
7. A heat-sealed flexible plastic film en- 
closure for a grinder or blender can be used, 
but It must be opened in a Biological Safety 
Cabinet (7) . 
8. Blender bowls sometimes require supple- 
mental cooling to prevent destruction of the 
bearings and to minimize thermal efforts on 
the product (7) . 
9. Before opening the safety blender bowl, 
permit the blender to rest for at least one 
minute to allow settling of the aerosol cloud. 
10. Clinical or other laboratories handling 
human blood should be aware of the aerosols 
produced by the micrphaematocrit centri- 
fuge, the autoanalyzer stirrer, and the mi- 
crotonometer, inasmuch as it seems that 
airborne transmission of infectious hepatitis 
may occur in the laboratory (20) . 
G. Miscellaneous Precautions and Recom- 
mendations 
1. Water baths and Warburg baths used to 
inactive, incubate, or test infectious sub- 
stances should contain a disinfectant. For 
cold water baths, 70% propylene glycol is 
recommended (4, 10). 
2. Deepfreeze, liquid nitrogen, and dry ice 
chests and refrigerators should be checked 
and cleaned out periodically to remove any 
broken ampoules, tubes, etc., containing in- 
fectious material, and decontaminated. Use 
rubber gloves and respiratory protection dur- 
ing this cleaning. All infectious or toxic 
material stored in refrigerators or deepfreezes 
should be properly labelled. Security meas- 
ures should be commensurate with the haz- 
ards (4, 10, 21). 
3. Freeze-dried culture ampoules should 
always be opened in a Biological Safety Cabi- 
net. The ampoule should be wrapped in a 
disinfectant-soaked swab before breaking it 
open to minimize the risk of cutting the 
hands, and to a lesser extent of releasing 
aerosol of dried material. Whenever possible, 
ampoules should be filled with dry nitrogen 
after freeze -drying, thus avoiding implosion 
that may occur during the sealing as well 
as opening of evacuated ampoules. The whole 
process of freeze-drying Itself should be per- 
formed in a Biological Safety Cabinet. Filtra- 
tion of the effluent air from the vacvium 
pump is desirable either up (preferably), or 
down stream of the pump (5) . 
4. Ensure that all virulent fluid cultures 
or viable powdered infectious materials in 
glass vessels are transported, incubated, and 
stored in easily handled, nonbreakable leak- 
proof containers that are large enough to 
contain all the fluid or powder in case of 
leakage or breakage of the glass vessel (4, 10) . 
5. All inoculated pctri plates or other 
inoculated solid media should be transported 
and incubated in leak -proof pans or leak- 
proof containers (4, 10) . 
6. Care must be exercised in the use of 
membrane filters to obtain sterile filtrates 
of infectious materials. Because of the fragil- 
ity of the membrane and other factors, such 
filtrates cannot be handled as noninfectlous 
until culture or other tests have proved their 
sterility (4, 10) . 
7. Shaking machines should be examined 
carefully for potential breakage of flasks or 
other containers being shaken. Screw capped 
durable plastic or heavy walled glass flasks 
should be used. These should be securely 
fastened to the shaker platform. An addi- 
tional precaution would be to enclose the 
flask in a plastic bag with or without an 
absorbent material. 
8. No person should work alone on an 
extremely hazardous operation (4, 10). 
IV. PERSONAL HYGIENE, HABITS, AND PRACTICES 
Personal hygienic practices in the labora- 
tory are directed, in most part, toward the 
prevention of occupationally acquired phys- 
ical injury or disease. To a less obvious 
extent, they can raise the quality of the 
laboratory work by reducing the possibilities 
for contamination of experimental materials. 
The reasons for many of the recommended 
precautions and practices are obvious, but, 
in some instances, amplification will permit 
a better review of the applicability to any 
one specific laboratory. 
Consequently, what might be forbidden 
in one laboratory might be only discouraged 
in another, and be permissible in a third. 
Nevertheless, adherence to safe practices that 
become habitual, even when seemingly not 
essential, provides a margin of safety in sit- 
uations where the hazard Is unrecognized. 
The history of occupational Injury Is re- 
plete with examples of hazards unrecognized 
until too late. The following guidelines, rec- 
ommendations, and comments are presented 
with this in mind: 
1. Food, candy, gum, and beverages for 
human consumption will be stored and con- 
sumed only outside the laboratory (5, 10). 
2. Foot -operated drinking fountains 
should be the sole source of water for drink- 
ing by human occupants of the laboratory 
(27). 
3. Smoking is not permitted in the lab- 
oratory or animal quarters. Cigarettes, pipes, 
and tobabco will be kept only in clean areas 
(5, 10, 26) . 
4. Shaving and brushing of teeth are not 
permitted in the laboratory. Razors, tooth- 
brushes, toiletry supplies, and cosmetics are 
permissible only in clean change rooms or 
other clean areas, and should never be used 
until after showering or thorough washing 
of the face and hands (27). 
5. A beard may be undesirable in the lab- 
oratory in the presence of actual or potential 
airborne contamination, because it retains 
particulate contamination more persistently 
than clean-shaven skin. A clean-shaven face 
is essential to the adequate facial fit of a 
face mask or respirator when the work re- 
quires respiratory protection (10, 27, 31). 
6. Develop the habdt of keeping hands 
away from mouth, nose, eyes, face, and hair. 
This may prevent self-inoculation (10, 27) . 
7. For product protection, persons with 
long hair should wear a suitable hair net 
or head cover that can be decontaminated. 
This has long been a requirements in hos- 
pital operating ^ooIns and in the manufac- 
ture of biological pharmaceutical products. 
A head cover also will protect the hair from 
fluid splashes, from swinging into Bunsen 
flames and petrl dishes, and will reduce 
facial contamination caused by habitual re- 
petitive manual adjustment of the hair (5). 
8. Long-flowing hair and loose-flapping 
clothing are dangerous in the presence of 
open flame or moving machinery. Rings and 
wrist watches also are a mechanical hazard 
during operation of some types of machines 
(5. 10). 
9. Contact lenses do not provide eye pro- 
tection. The capillary space between the con- 
tact lenses and the'kornea may trap any ma- 
terial present on the surface of the eye. Caus- 
tic chemicals trapped in this space cannot 
be washed off the surface of the cornea. If 
the material in the eye is painful or the con- 
tact lens is displaced, muscle spasms will 
make it very difficult, if not Impossible, to 
remove the lens. For this reason, contact 
lense^ must not be worn by persons exposed 
to caustic chemicals unless safety glasses 
with side shields, goggles. Or plastic face 
masks are also worn to provide full protec- 
tion. It is the responsibility of supervisors to 
identifv employees who wear contact lenses 
(25, 26) . 
10. Personal items, such as coats, hats, 
storm rubbers or overshoes, umbrellas, purses, 
etc., do not belong in the laboratory. These 
articles .should be kept elsewhere (25). 
11. Plants, cut flowers, an aquarium, and 
pets of any kind are undesirable sources of 
yeast, molds, and other potential microbial 
contaminants of biological experimental ma- 
terials (25). 
12. Books and journals returnable to the 
institutional library should be jused only in 
the clean areas as much as possible (10, 27). 
13. When change rooms with showers are 
provided, the employer should furnish skin 
lotion (27) . 
14. When employees are subject to potential 
occupational Infection, the shower and/or 
face/hand-washlng facilities should be pro- 
vided with germicidal soap (8, 27) . 
15. Personal cloth handkerchiefs should not 
be used in the laboratory. Cleansing tissue 
should be available instead. 
16. Hand washing for personal protection: 
(i) This should be done promptly after re- 
moving protective gloves. Tests show It Is not 
unusual for microbial or chemical contami- 
nation to be present despite use of gloves, 
due to unrecognized small holes, abrasions, 
tears, or entry at the wrist. 
(il) Throughout the day, at intervals dic- 
tated by the nature of the work, the hands 
should be washed. Presence of a wrist watch 
discourages adequate washing of the wrist 
(10,25). 
(Hi) Hands should be washed after remov- 
ing soiled protective clothing, before leaving 
laboratory arpa, before eating, and before 
smoking. The provision of hand cream by the 
employer encourages these practices (5, 8, 
10 ). ' 
(iv) A disinfectant wash or dip may be de- 
Eir'able in some cases, but its use must not 
be carried to the point of causing roughen- 
ing, -desiccation or sensitization of the skin. 
17. Anyone wltlf a fresh pr healing cut. 
abrasion, or skin lesion should not work 
with infective material unless the injured 
area is completely protected (8, 25). 
18. Persons vaccinated for smallpox may be 
shedders of vaccinia virus during the phase 
of cutaneous reaction. Therefore, vaccination 
requires permission of the appropriate super- 
visor, because two weeks’ absence may be 
necessary before returning to work with 
