SEE INTERESTING ARTICLE BELOW:
Q: I am finding that some of my water jobs quickly get a
musty odor, much like a moldy smell, even when I arrive the same day the loss
occurs. Why can I smell mold that quickly?
A: Actually, mold growth does not begin to become
microscopically detectable until eight to 10 days after the water incursion,
and is not visible until 18 to 20 days.
For more information on this, before we get into this
particular discussion about the cause of some of these odors you are
encountering, please see the article in the May issue of Cleanfax magazine for
the peer reviewed scientific documentation.
As a water damage technician, we show up at a water job and
there is that tell-tale musty, moldy odor. We may even start the drying process
when there is no odor, and the next day that musty odor has appeared.
What is causing this odor? If the odor is not caused by
mold, then what is causing it? The answer is probably bacteria.
It is true that the odor could be from old mold. Assuming a
normal response time to a water loss of 12 to 24 hours, then for the odor to be
coming from mold would mean that the mold was already there before the water
loss — thus a pre-existing condition. So if mold is not visible, the source of
the odor is probably bacteria.
Bacteria basics
Before getting into what to do about the bacteria that is
causing the odor at the water loss, we need to understand what bacteria are,
and if they pose a health hazard.
According to paleontologists, who are scientists that study
the history of life on Earth, bacteria were the first life form to develop on
Earth.
Bacteria have the largest numbers of any life form on earth.
It is estimated that there are 5 x 10 to the 30th power of bacteria on Earth
(this number is a 5 followed by 30 zeros).(1)
The microbiologists who study bacteria estimate that there
are 10,000,000 species on earth, with only about 9,000 having been identified.
In comparison, there are about 5,500 identified species of mammals on earth.
Bacteria live everywhere on Earth, and live on everything on
earth. Actually "cataloging" all bacterial life will probably never
be accomplished. If you went into your back yard and took a shovel of dirt, in
that shovel would be an estimated 2.2 million bacteria.(1)
Looking at bacteria from a different perspective, a weight
perspective, here are some interesting statistics:
There are about 6.8 billion humans on Earth, and if each
human weighs an estimated 160 pounds, then the total weight of the human
population on earth would be about 1.1 x 1012 pounds, this 1.1 x 10 to the 12th
pounds. As an example of how big this number is, if we stacked one dollar bills
on top of each other, this amount of 1.1 x 1012 of dollar bills would reach the
moon, which is about 240,000 miles from Earth.
The total weight of bacteria on Earth is estimated to weigh
1 x 10 to the 15th pounds.(1)
Thus the total weight of bacteria on Earth is much larger
than the weight of all the humans on Earth.
Bacteria have always been here and have always been very
abundant.
When most of us hear the word bacteria, we have an immediate
negative reaction. The word "bacteria" to most of us means sickness,
illness and disease, among others. Nothing could be further from the truth. If
it was not for bacteria, the human race would not exist. Bacteria are 100
percent essential for us, as humans, to live. A few examples:
Bacteria on your skin (2)
1,000 different species
Different species live on different regions of the human
body
Many act as defense mechanism against pathogenic bacteria
Bacteria in your mouth (3)
500 to 1,000 different species
Even after brushing and rising with mouthwash, thus killing
most bacteria, the bacteria regenerate in about two hours (which is a good
thing)
These bacteria are a major bodily defense mechanism
Bacteria in your large intestine (4)
700 different species of bacteria, weighing about 4 pounds
Produce vitamin K, vitamin B, thiamine, riboflavin
Digest fiber.
Bad bacteria
While there are thousands of bacteria which live on us, in
us, and protect us, there are some "bad" ones.
There are hundreds of species of bacteria that can, and do,
cause sickness and disease. These are called pathogenic. The ones we hear about
most often are the likes of Escherichia coli (E-coli), Salmonella, Shigella,
Streptococcus, pneumonia, tuberculosis, cholera, etc.
And, we have just seen an apparently new bacteria strain of
E-coli in Europe.
In most buildings, the common types of bacteria that are present
include micrococcus, staphylococcus and bacillus. All of these live on our
human skin and are mostly benign.
The reason these bacteria are found in buildings is that we,
as humans, shed our surface layer of skin and these bacteria are also shed with
the dead skin cells. So, while there can be pathogenic bacteria in buildings,
they are normally not present.
While pathogenic bacteria are cause for concern, they can be
destroyed by the proper use of biocides/antimicrobials, or by taking away one
of their requirements for life, either their food source or water.
Bacteria growth
Bacteria are single-celled forms of life that are very small
in size, about 0.2 to 1 micrometers in diameter. As a comparison, a human hair
is 40 micrometers to 120 micrometers in diameter and photo copy paper is about
100 micrometers.
Bacteria reproduce by a process that is called binary fission,
which means they split from one cell into two cells. Many species of bacteria
can reproduce almost continually.
The "splitting" can occur as fast as every 15
minutes, which is much quicker than mold reproduces. While this does not seem
very quick, watch the math: (5)
Start with one cell, 15 minutes = 2 cells, 30 minutes = 4
cells, 45 minutes = 8 cells, 60 minutes = 16 cells
Four hours after the start = 65,536 cells
Eight hours after the start = 4,294,967,296 cells, almost
4.3 billion cells.
With this reproduction rate, the quantity of bacteria
literally explodes. Even if we respond to the water loss eight hours after the
event, we are caught behind the curve.
The numbers go beyond imagination if you look at 24 hours,
since the quantity can keep doubling every 15 minutes.
With bacterial growth rates that are exploding at a water
loss, they have to obtain energy to survive, grow and continue their
reproduction.
Bacteria obtain energy from digestion. Bacteria's digestion
occurs outside of the organism and one of the by-products of this process is
off-gassing, which creates the musty odor that we probably smell at the routine
water loss.
The odor that becomes noticeable at a water loss can be very
similar to odor given by mold. These odors are known as microbiological
volatile organic compounds (MVOCs). It is this off-gassing that could be the
odor that is present when we arrive and/or could be the odor that appears on
day two of the water loss.
Many times, you will hear water damage technicians say something
like, "I am applying a biocide to stop the odor from showing up on day
two."
What the technician is, in effect, doing is applying a
biocide to kill the bacteria which eliminates the generation of MVOCs.
Fighting the bacteria
The ways to minimize, reduce or eliminate bacteria are by
proper cleaning, drying and the application of biocides.
There are many different formulations of effective biocides
that are routinely used to kill bacteria on a water loss. Many of these
solutions use, as their primary "killing" chemicals, the same
chemicals that we find in everyday life. Here are some examples:
Hydrogen peroxide used on cuts to kill bacteria
Phenols, which are used in biocides, are also the same used
in a popular mouth wash
The orange colored biocide that is used by phlebotomists on
your arm before taking blood is iodine, which is known as an iodophor in
chemical terms
Quaternary ammonium compounds are used in household
cleaners/disinfectants that are used in bathrooms and kitchens
Hypo-chlorites that are in solutions are also used in your
clothes washer to clean whites, commonly called bleach.
While there is justifiable concern about misuse of biocides,
most of the biocides used in our industry have been around for years and when
used properly can kill both bacteria and mold and do not pose a human health
risk.
"Killing" mold is not an acceptable method of mold
remediation, but that is for another article. Killing bacteria with biocides is
a very acceptable method of decontamination. It is routinely done in hospitals,
doctors/dentists offices, food process facilities, restaurants, etc.
Bacteria, like all forms of life on Earth, needs water to
live. Below is a table showing different levels of water activity and the type
of microbial life each level supports.
Water activity is the water that is available to support
microbial life at the very surface level of a material, which is the location
where we find microbial growth.
Water activity and moisture content are somewhat related,
but a full discussion is for another article.
Water Activity (wetness) - Minimum to support Life Form Supported
0.95 Bacteria
0.88 Most Fungi
0.66 to 0.70 Mold:
Penicillium, Aspergillus
As can be seen from this chart, bacteria need a lot of water
to live. In fact, bacteria needs more water to live than does mold. As a
comparison, the average human should consume 25 ounces of water per day. Less
than this amount may lead to health problems. With water activity, if the
amount of water is below the above values, then there is not enough water for
microbial life to live.
When water is taken away from bacteria, they die; some types
of bacteria will generate spores as the living bacteria die. This is different
from mold. When water is taken away from mold, mold goes into a state called
dormancy. Mold, in effect, goes into a waiting pattern for water to return — it
does not die.
Thus, drying can be an effective bacterial killing method.
Musty odors
Back to our tell-tale odor at the water loss. That musty
odor can be a sign of mold growth, which may not be visible. Mold can be living
and growing inside wall cavities, under cabinets, under carpet/pad and in other
"hidden" locations.
However, the odor you encounter is more likely caused by
bacteria that are ever-present in homes and grow very rapidly when exposed to
water.
If you find mold right after a water loss, it is most likely
pre-existing, and not from the immediate water loss.
The best method to reduce bacteria and their odors and
potential negative health impacts is by:
Properly cleaning the affected areas
Drying the structure
Appropriate use of biocides.
If a structure is clean and dry, then there cannot be any
microbial life.
References:
(1) Whitman,
W. B., Coleman, D. C., Wiebe, W. J. "Prokaryotes:
The unseen
majority." National academy of Sciences, pp 6578
– 6583. June
1998, University of Georgia, Athens, GA
(2) Todar K.
Normal Bacterial Flora of Humans Todar's Online
Textbook of
Bacteriology
(3) Zimmer,
Carl. "How Microbes Define and Defend Us." Science,
New York Times.
12 July 2010
(4) Maton,
Anthea; Jean Hopkins, Charles William McLaughlin, Susan
Johnsons,
Maryanna Quon Warner, David LaHart, Jill D. Wright
(1993). Human
Biology and Health. Englewood Cliffs, New Jersey,
USA: Prentice
Hall
(5) Zwietering
M H, Jongenburger I, Rombouts F M, van 'T Riet K
(1990).
"Modeling of the Bacterial Growth Curve". Applied and
Environmental
Microbiology 56 (6): 1875–1881
Richard Driscoll has a B.S. degree in mechanical engineering
from Clarkson College of Technology, an MBA from the University of Dayton and
is currently working on his doctorate. He is a professor at Webster University,
where he provides graduate and under-graduate level lectures on marketing,
international business management and business metrics. He is an Institute of
Inspection, Cleaning and Restoration Certification (IICRC) Certified Master
Restorer and an approved instructor. Driscoll has been consulted by state
governments on legislation related to the cleaning and restoration industry. He
also is the author and instructor for Restoration Sciences Academy's MR-110 and
MR-210 microbial remediation classes. He can be reached at Richard@mayhemmishaps.com.
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