DISINFECTION AND FUMIGATION
DEFINITIONS
Disinfection
When an object is contaminated with so-called pathogenic germs it
is said to be infected. To disinfect an object it is necessary
to destroy the microörganisms. The destruction of all so-called
pathogenic germs, whether in the substance of the object or on its
surface, is called disinfection. All lower forms of animal and
vegetable life are destroyed in sterilization, while in disinfection
only the germs which, from the medical standpoint, are the cause of
dis-ease, are destroyed. The agent used in disinfection is known as a
disinfectant or germicide.
Sterilization
The destruction of all germ life in or on an object is known as
sterilization. From the standpoint of hygiene sterilization is
unnecessary except in dis-eases such as anthrax, tetanus, and
other spore-bearing dis-eases, the spore being highly resistive
and not so easily destroyed as the vegetative cells. Sterilization
will disinfect but disinfection will not necessarily sterilize.
Disinfection is thoroughly efficient in almost all cases.
Sterilization destroys all life.
=Antiseptic= (Anti, against, and septos, putrid)
An antiseptic prevents putrefaction but does not necessarily destroy
the microörganisms. A substance may act as an antiseptic by delaying
or preventing the processes of decay and decomposition, but still
not be a germicide. In other words, anything that will hinder the
development of germ life acts as an antiseptic. Thus cold has a
preservative action, although it will not destroy the microörganisms.
A disinfectant may be diluted and used as an antiseptic. A 10%
solution of formalin is a good disinfectant and will kill bacteria in
a relatively short space of time, but formalin in a solution of one
to fifty thousand will be a very good antiseptic. The germination of
anthrax spores may be prevented by the use of bichloride of mercury
in as weak a solution as one to three hundred thousand, but it will
require a solution of one to one thousand to destroy the spores.
A disinfectant is also an antiseptic but an antiseptic is not a
disinfectant.
Asepsis
Asepsis is an absence of putrefactive bacteria. This may be
accomplished without the use of germicidal agents by cleanliness
which excludes all so-called pathogenic germs.
Insecticide
An insecticide is an agent capable of destroying insect life. Many
of the germicidal agents are also insecticides. There is a great
difference in the resistance of different insects. Formaldehyde is
a good germicide but is not an insecticide. There are four ways of
using insecticides. In liquid form, powder, vapor form and those
placed in food to be eaten by the insects.
Germicide
A germicide and a disinfectant are the same for they both destroy
germ life. Many germicides are so powerful that they completely
sterilize or destroy all life.
Deodorant
A deodorant is not in any sense a disinfectant and has no power
to destroy germ life. It is an agent which neutralizes unpleasant
odors. A disinfectant destroys germs but does not necessarily
destroy odors. A deodorant must not be confused with a substance
having pungent odor which merely substitutes one odor for another. A
deodorant destroys the unpleasant odor.
Fumigation
Fumigation is a means of disinfection by use of fumes or gases, and
is used generally for the purpose of destroying germ life only on the
surface of objects. For this reason fumigation should not be used as
a substitute for disinfection. Formaldehyde and sulphur dioxide are
used largely for fumigating purposes.
Of these two gases formaldehyde is the better since it is not
poisonous, does not injure the surface of objects and will not damage
the most delicate fabrics nor destroy colors. Sulphur dioxide is very
destructive and therefore less desirable. However, all the gaseous
agents lack sufficient penetrative power to accomplish more than a
surface disinfection. Formaldehyde is a good germicide and this adds
to its efficiency.
To obtain the desired results in fumigating there must be special
attention given the preparation of the rooms or spaces to be
fumigated. All objects in the room should be so exposed that the gas
may readily get to all surfaces. All furniture and other objects
should be moved into the room away from the walls and all doors and
drawers of bureaus and boxes should be opened so the gas may find
free access to every nook and corner. Much of the gas may escape
through cracks and crevices, therefore special care must be exercised
that these openings are all properly closed before the fumigation is
started. In view of the fact that the gas is non-destructive there is
no harm done even to the most delicate materials.
The best results are obtained from the formaldehyde when the
temperature of the room is 65° F. or over, with a relative humidity
of at least 60%. While formaldehyde has the power to kill spores
it is not considered sufficient to disinfect in such dis-eases as
anthrax and tetanus.
Formaldehyde gas kills all forms of microörganisms almost instantly
but is not particularly destructive to higher form of life.
It produces a marked irritation in the mucous membrane of the
respiratory tract which may result in death to animals exposed to the
gas for any length of time. It is not considered an insecticide.
In fumigating a room with formaldehyde great care must be exercised
that the individual does not remain in the room after the gas begins
to be liberated. After the process of fumigation has been completed
the windows and doors should all be opened that the gas may escape.
It is always best to have the doors and windows open from the outside
so that it will not be necessary for any one to go into the room
until the gas has blown out.
AGENTS OF DISINFECTION
Physical Agents
The physical agents of disinfection are sunlight, electricity,
pressure, dry heat, burning, boiling, and steam.
Chemical Agents
Chemical agents of disinfection are divided into two
divisions—gaseous and liquid disinfectants. The gaseous disinfectants
are: formaldehyde gas, sulphur dioxide gas, hydrocyanic acid gas,
chlorin, oxygen, and oxone.
Some of the most important liquid disinfectants are metallic salts,
bichloride of mercury, silver and zinc salts, coal-tar creosote,
carbolic acid, phenol, lysol, creolin and formalin.
MEANS OF DISINFECTION
Natural Means
Nature’s means of disinfecting are by dilution, sunlight,
desiccation, time and antibiosis. The direct rays of the sun are
Nature’s greatest germicide. Few of the microörganisms will live in
the direct rays, but there are none that will withstand them for more
than a few hours. Germs can not withstand the effect of dryness.
Thus we see there is in Nature that which works as a most efficient
germicide. The combination of sunlight and dryness forms a most
desirable means of disinfection. When germs become attenuated through
the effects of these natural processes they do little harm when
introduced into the body.
One of the most important adjuncts to the work of disinfection is
personal cleanliness and sanitation of the environment.
Other Agents
=Fire= is not a practical disinfectant. It can be used only with
those articles that are of little or no value since the article
that is being disinfected is destroyed. The burning of all refuse
and garbage is by all means the best method. Burning is the most
satisfactory and cheapest method in disinfecting sputum and other
excreta from the body, and in disposing of articles of little value
saturated or contaminated with such.
The =dry heat= method of disinfecting requires specially built
apparatus such as dry air sterilizers. This form is not practicable
for use in disinfecting fabrics and other materials that are
destroyed or injured by extremely high temperature required to
destroy the germ life. Metals are easily injured by this method as
they are likely to be scorched. All forms of life are destroyed in an
hour’s time when exposed to a temperature of 150° C. Such articles
as glassware will withstand this heat or even higher and may be
thoroughly sterilized in from one to two hours. This insures proper
penetration and sufficient heat to completely destroy all life.
=Boiling= is one of the most satisfactory and easiest methods of
disinfecting. Continuous boiling for an hour in water at 100°
C. will result in the destruction of most germs of the so-called
infectious dis-eases. There are some of the spores, such as those of
anthrax and tetanus, that will survive the most strenuous processes
of boiling. However, most of the germs will be destroyed before the
boiling point is reached.
Boiling is the best method to be used in disinfecting bedding, body
linen, towels and other fabrics which will not be harmed by this
process. There is a great variety of articles that may be disinfected
in this way, such as utensils and bed pans. The surfaces of the
floors, walls, beds, and other objects may be cleansed with boiling
water. In this use it is advisable to add some disinfectant to the
water.
=Steam= is not only a disinfectant but it is also a sterilizing
agent. All forms of germ life, including spores, are completely
destroyed. It is therefore our best known disinfectant. There are
many objects that are injured and some ruined by steam, such as
silk, wool, furs, oilcloth and rubber goods, and articles containing
varnish or glue. There is danger from staining and running of colors.
Disinfection may be either with streaming steam or with steam under
pressure. For the use of streaming steam no particular device is
necessary. Some means of providing the steam and some place to hang
or place the objects and articles to be disinfected are the two
essentials for this method. It is not necessary to have an air-tight
place. To use steam under pressure there must be a specially
constructed apparatus. There are many such devices on the market
and they are used in institutions where it is found necessary to
disinfect with steam.
Sterilization may be accomplished in twenty minutes with steam at
about one atmosphere of pressure which will give a temperature of
about 120° C. A temperature of about 125° C. is obtained with the
pressure at about twenty pounds to the square inch. This reduces the
time for sterilization to about fifteen minutes.
Other Disinfectants
Carbolic acid which is a good antiseptic but a comparatively mild
germicide is another disinfectant. It has very little penetrating
power and is of most value in a 3% to 5% solution for washing floors,
walls and woodwork. The cresoles are more powerful and effective
disinfectant than carbolic acid. The most common of this group are:
creoline, lysol, and saprol. Their use is about the same as that of
carbolic acid. Bichloride of mercury may be used in a solution of
from one to two thousand, to one to five hundred and forms a very
good disinfectant. It kills germs but corrosive sublimate will kill
spore-bearing bacteria only in a solution of one to five hundred. In
weaker solutions it forms a very good antiseptic. Lime forms a very
good disinfectant, especially for excreta, cesspools and cellars.