Park Falls "Town Hall" brochure V.2
F.A., Feb. 2005
title Escherichia coli- friend or foe?
"Public health officials have closed Jones beach due to the high numbers of
Escherichia coli (E coli) detected in the water." "E. coli has been found in
increasing numbers in several wells near the community of Farmington. Residents
are upset and blaming the nearby cattle operations of Smith Farms."
"High numbers of E. coli and fecal coliform bacteria detected in Blackfly River
have been traced back to the biotreated wastewater released by the White
Company Pulp and Paper Mill"
Sound familiar? To public health officials, E. coli is a key indicator of
microbial health hazards, yet the body of every human (and other mammals) is
home to billions of E. coli cells throughout life. What does it mean to detect
E. coli in different locations? Does the presence of E. coli always indicate a
health hazard? This brochure was written to help you, the informed citizen,
understand what finding E. coli means.
What is E. coli?
The Earth's living skin, the biosphere, is filled with bacteria. Most do
essential things, such as turning dead plants and animals and their wastes into
soil, releasing nutrients to the environment, and putting atmospheric nitrogen
into forms usable by animals and plants (like trees). Other bacteria, called
commensals or symbionts, live with (in or on) plants and animals. E coli is a
commensal bacterium living in the large intestines of most mammals, including
humans.
E. coli the friend
When infants, we acquire E. coli, usually from our mothers. It's the start of a
life-long relationship. We supply our E co//with shelter, food, and water. In
turn, E coli increases our resistance to intestinal parasites (disease-causing
microbes), stimulates our immune systems to develop and perform better, and
supplies some B and K vitamins to us.
E. coli the "indicator"
Many of the worst diseases afflicting humans (such-.as cholera, dysentery,
salmonellosis, typhoid fever, polio, and hepatitis A) are transmitted by sewage
and fecal contamination of our food and water. Since it is very hard to test
directly for all the microbes causing these diseases, it was proposed about a
century ago that E coli, always present in feces in large numbers and easy to
test for, be used as an indicator of fecal contamination. At that time, it was
believed that E. coli couldn't cause disease itself, although fecal
contamination was easily shown by the presence of E coli.
Applying this logic to testing in places where fecal contamination was likely,
such as water supplies, hospitals, schools, meat, milk, and vegetable
processing, restaurants, etc. produced really big improvements in public health.
Using E coli as an indicator was (and is) a very successful strategy- but not
everywhere!
E. coli the pathogen
E. coli are not all the same! Within the species coli are hundreds of strains or
types, just like Maltese, Labradors and St. Bernards are all types of dogs in
the species C. familiaris. Most types of E. coli are harmless or "nonpathogens", but a few can cause disease. They are pathogens. Therefore, we
should be concerned if we find E. co// because: (a) it may indicate sewage
contamination; or (b) it may be harmful itself.
So what's different about E. coli in pulp and paper mill effluents?
Making paper from wood takes a lot of heat and water. Most pulp and paper mills
use river or lake water, further purified by reducing its sediment and bacterial
content. After use, the mill bio-treats the water to remove wood debris, oxygen
demand, and excess nutrients, then releases it back to the river or lake. In
most mills no sewage enters this system. Nevertheless, recent scientific
research has shown that virtually every pulp mill wastewater treatment system
contains E. coli, because E. coli live and grow continuously in the warm waters
of the mill and bio-treatment system, independently of any fecal source or
sewage. We also know now that some E. coli "environmental" types can be found
associated with bark, soil, and trees.
How does this affect the importance and meaning of finding E. coli in the
mill wastewater?
If E. coli actively grows in the mill water system in the complete absence of
sewage, then their numbers give no indication of whether there is a sewagelinked health hazard. In short, E. coli can't be used as a health hazard
indicator in such pulp and paper mills- or in the wastewater from them.
OK, but even if the E. co//from the mill are useless as health hazard
indicators, couldn't they still be pathogenic types?
Normally pathogenic E. coli come from sick people and animals, not wood and
water, but yes, they could. To see if they are, the mill water E. coli can be
collected and tested. Only if the E. coli types present carry certain genes for
toxins or "invasiveness" can they cause harm to humans and animals. So far, all
the E. coli strains found at several Canadian mills and tested have proven to be
harmless types.
So what can be done to ensure that there are no microbial hazards in a
certain mill's wastewater?
1. Be certain that there is no sewage entering the mill water system.
2. Test to be sure that the E. coy/types present are not pathogens (diseaseproducing types).
3. Test for any other pathogens likely to be present. This extra testing, almost
never done in other situations, will give us further assurance that the biotreated mill waters contain no microbial hazards.
Buzzwords
Technical and scientific words usually salt stories and discussions of E. coli
and health hazards. Knowing exactly what each means is necessary for the nonspecialist to really understand the issues.
Activated sludge-a speeded-up, intensified version of the natural microbial
process by which rivers and lakes purify themselves. It is used worldwide to
treat sewage and industrial wastes.
Coliforms A group of closely related bacteria that includes E. coli. Many are
found in nature and unrelated to fecal waste, so "coliform counts" are rarely
used any more to indicate sewage.
E. coli -a usually harmless bacterium typical of fecal material and found in the
intestines of nearly all mammals.
E. coli 0157-The most common and dangerous pathogenic strain of E. coli.
Fecal coliforms A sub-group of coliforms able to grow at 44.5°C (112.1°F). They
may be, but are not necessarily, from fecal material.
Indicator organism- An organism whose presence and numbers are used to
indicate the presence of another organism or substance.
Pathogen A type or strain of microbe capable of causing detectable disease in
humans, animals, or plants.
Salmonella, Shigella Bacterial groups that are close relatives of the coliforms,
but which are usually human pathogens.
Total counts Counting the total number of living bacteria in a certain volume of
water. Most are usually harmless "environmental" types.
Viable counts Tests which measure the number of living bacterial cells in a
certain volume of water. Many regulations are based on viable counts.
Wastewater bio-treatment The use of a microbial system (like activated sludge)
to remove toxicity, oxygen demand, and contaminants from water.
Written by Dr. Frederick Archibald, Ph.D.
Microbiologist
Adjunct Professor, McGill University,
Montreal
Subject Editor, Water Quality Research Journal of Canada