A Medical Doctors View of Sludge/biosolids and emerging diseases
"This leaves the patient base standing naked."
By Dr. Edward McGowan
Perhaps one of the areas currently neglected in the consideration of emerging diseases is the
transfer of pathogens or their genetic material through wastewater and wastewater treatment
products. In the case of SARS in Toronto, careful account of people was kept, but no attention to
their waste discharge was evidently considered.
Thus, an area that may be worth considering from a public health perspective---is the transfer of
mobile genetic elements and development and augmentation of antimicrobial resistance within
sewer plants. The discharge of wastewater products may assure wide spread dispersal within the
environment and transfer back to man and his animals. Thousands of tons of sewer sludge and
septage are spread across North America. In many cases, this material is top-dressed onto
irrigated pasture (see insert immediately below).
A free family celebration will take place from 2 to 4 p.m. today at the city of Los Angeles' sewage
sludge farm south of Bakersfield.
The Harvest Festival BBQ will be held at the Green Acres Farm conference center. The event
includes food, games for children, farm tours, giveaways and more.
Some 99 percent of the city of Los Angeles' human and industrial sewage is trucked to the Green
Acres farm, where it is used to grow crops fed to local dairy cows.
While cattle are to be excluded for 30 days before being returned, this says nothing of non-
domestic animals. Geese were recently implicated in the transfer of resistance. The question that
remains unanswered, where these birds on sludge applied lands? Considering the capacity of
genetic material move between the three kingdoms, Eukaryots, Archaens, and Prokaryotes and
then within viruses. Vast amounts of sludge may offer a fairly significant avenue for the spread of
disease and the intermixing of genetic information with different vectors. This is an area that is
essentially ignored and virtually uncontrolled under current standards.
I originally got into this area because of my interest in utilizing sewer sludge for agriculture and was
on a multi-jurisdictional panel that looked at the subject for Santa Barbara County. The panel was
composed mainly of wastewater engineers. I was the only person on the panel with a degree in
medicine. I also have a PhD in water quality and a primary degree in agriculture from UC Davis and
was the U.S. Department of State's environmental advisor to 22 African nations, thus am somewhat
familiar with the subject. In addition, I helped Uganda in setting up its set of national environmental
standards, including issues of biodiversity.
Following a fairly extensive review of land application of biosolids and the subject of resistance
while on the multi-jurisdictional panel, I found it worrisome as currently conducted. Thus my initial
infatuation with the subject took on an entirely different view.
I provide the following as furtherance of academic and practical interest. I would appreciate some
Preface. The document below, a work in progress, is written to the non-technical policy maker. It
was felt that this audience warranted a simplified and perhaps more comfortable review, yet one in
which the salient points might be grasp.
Abstract. This paper presents an argument that increased antimicrobial resistance, especially as
now found emerging in the community may be related to inadequate water quality standards. This
increasing level of community acquired resistance will see health care costs escalate and, until the
entire picture is within focus, efforts of control at the clinical level may be thwarted. Contrary to
popular contention, over use of antibiotics may play a diminishing role in the advancement of
resistance. The more profound but little discussed source may be found at the local sewer
treatment plant. The author contends that misplaced economics and political interference have
played a major role is this situation.
Based on industry dogma, land application of sewer sludge is a benign and beneficial activity. If
however, one reviews the current medical and scientific literature, a different picture emerges.
Thus, the issue takes on aspects of a political and not a scientific argument. In the interim, most
regulatory agencies have backed off. This leaves the patient base standing naked. Some portions
of the population are at higher risk when considering infection.
Diabetics are one such group. There is a rising level of diabetes and pre-diabetes within this
nation. Using the figures from Kaufman  and Peters , there are at least 18 million Americans
with diabetics and another 45 million that could be considered as prediabetic. These numbers
however may be on the conservative side. It is also known that about one half of the skin lesions
seen in the Los Angeles Basin are now methicillin resistant Staphylococcus areus (MRSA).
It is also common knowledge that diabetics, especially poorly controlled diabetics, have
compromised immune systems, poor vascular systems, are prone to lower limb ulcers that heal
poorly, if at all. The end result is often amputation of digits and then limbs. This, when combined
with resistant pathogens, drives up morbidity and mortality, saps and diverts already over extended
health care resources, and importantly drives up health care costs.
The contention of this paper is that while over-use of antibiotics may play an important role in the
advancement of resistance, other causes are overlooked. Some might even say--purposefully
A critical but less well understood mechanism for the transfer of multi-drug resistant pathogens is
found at the local sewer treatment plant . As bacteria, other pathogens, and common
background-organisms wind their way through these treatment processes, the selective pressures
against them increase. In consequence, there is a greater effort by these organisms to pass on
survival enhancing genetic information. Additionally, as the environmental stresses increase, these
organisms up-regulate numerous other survival mechanisms to assure that they and their genetic
material survive. These can include chlorine resistance.
Many antimicrobials or their metabolites pass through the body essentially unchanged. Thus feces
and urine do contain some impressive levels. As later noted, Kummerer has followed this and
noted levels that are able to induce or maintain resistance. Added to this are the other materials
dumped into the toilet or down the drain that confer resistance. This includes discarded antibiotics
and disinfectants. Triclosan, a ubiquitous biocide has been suspected of inducing resistance.
In one of the several major studies looking at sewer plants, the scientists followed bacteria through
a sewer treatment works . Fecal coliforms were the test organism. These bacteria were isolated
at various locations in the plant as the sewage was passing through the treatment process. They
were isolated from: a) the inlet, b) the primary sedimentation tank, c) the activated sludge digestion
tank, d) the final settling tank, e) the outlet and f) the return activated sludge drain. They were then
examined for multi-drug antibiotic resistance. The study looked for the presence of drug resistant
plasmids. The scientists were able to distinguish resistant bacteria from those still sensitive to
antibiotics. Several drugs were tested and included tetracycline, kanamycin, chloramphenicol and
streptomycin, ampicillin, nalidixic acid, rifampicin, and sulfisoxazole. A total of 900 separate tests
were conducted. Of these over half contained multi-drug resistant plasmids.
While this is interesting, there was a new finding that raised considerable concern. The further
along that the wastewater had progressed through the treatment process the greater the tendency
was development of multiresistant strains. Additionally, the study demonstrated that these multi-
resistant bacteria also simultaneously carried, and then passed around their multiple transferable
drug-resistance plasmids. Thus, the take-home message is that drug resistance and the transfer of
multi-drug resistant occurs in wastewater treatment plants . This information is now well over a
decade old. These data were a harbinger, yet little impact from such studies has been noted.
Sewer sludge, as produced under current standards, allows the survival of up to 2-million viable
coliform per gram. The use of low-level indicator bacteria, along with the apparent lack in
understanding of antibiotic resistance within EPA (see search results at bottom of this file) should
alert anyone that the issue is anything but closed. By its refusal to adequately present necessary
analyses in this area, EPA has not only manufactured uncertainty, but also potentially increased
the risk of human disease, disease from some serious pathogens that may not respond to current
All Class-B sewage sludge technologies that are normally used in the U.S. such as anaerobic
digestion and aerobic digestion and heating at these levels as well as composting and land
stabilization do not effectively destroy critical pathogens . Neither is their genetic material
destroyed and this and its lack of acknowledgement is a critical shortcoming within EPA. Thus if
there is antibiotic resistance, it may be passed through these processes to background organisms
including man . Actually several studies have documented passage of genetic information to
background environmental systems and such systems can act as lending libraries for this genetic
information. Man and animals are exposed daily to such backgrounds .
So, how fast can resistance progress and to what ends. Let me give an example.
The following is extracted from the recently published medical text by Christopher Walsh of the
Harvard Medical School—Antibiotics, Actions, Origins, Resistance, (March 2003) New York: ASM
Resistance to atibiotics is not a matter of IF but one of WHEN. Schentag, et al., as presented in the
Walsh text, looked at how rapidly resistance could be generated. They followed surgical patients
with the following results. Pre-op nasal cultures found Staphylococcus aureus 100% antibiotic
susceptible. Pre-op prophylatic antibiotics were administered. Following surgery, cephalosporin
was administedred. Ninety percent of the patients went home at post-op day 2 without infectious
complications. Nasal bacteria counts on these patients had dropped from 10 to the 5th down to 10
to the 3rd, but were now a mix of sensitive, borderline, and resistant Staph, where prior to surgery
all had been susceptible to antibiotics.
For the patients remaining in the hospital and who were switched on post-op day 5 to a second
generation cephalosporin (ceftazidine), when assayed on post-op day 7, now showed bacterial
counts up 1000 fold and most of these were methacillin resistant Staph aureus (MRSA).
Then these patients were switched to a 2-week course of vancomycin. For those still in the hospital
on day 21, cultures revealed vancomycin resistant enterococcus (VRE) and candida. Vancomycin
resistant enterococci infections produce mortality rates of between 42 and 81%.
Note in the above, that these patients harbored NO resistant bacteria in their nasal cavities upon
entry to the hospital. But what would be the result if there had been inadvertent acquisition of
resistance from environmental contamination such as through sewer sludge? Gerba and Rusin 
for example have written on the passage from finger to mouth of pathogens found on typical
Others have written on dust as a mechanical vector of pathogens. Thus what of the home down
wind from land application of sewer sludge or from a sewer sludge composting facility? Gerba and
others have written extensively on the survival of pathogens and their viable infectivity once they
are absorbed onto sediments . Anyone who lives in an agricultural area knows that tillage and
wind cause large movements of soil and dust. The USGS has written extensively on the movement
of dust arising from Africa, moving across the Atlantic and carrying with it viable pathogens thus
causing respiratory disease in the Caribbean 
The indicator organisms used for Class B biosolids commonly involve E.coli and sometimes
Salmonella; these are the organisms that are killed normally by low-level disinfection. They are
vegetative bacteria that are highly susceptible to both chemical disinfection and heat disinfection. If
one looks, however, at the composition of sewage sludge and the range or organisms that are
present, one notes a wide range from things on the low end like the vegetative bacteria (E. coli,
salmonella, and staphylococcus) that are in sewage and end up in the solids. Also in the group of
highly susceptible and easily killed organisms are the enveloped viruses such as Hepatitis B., HIV,
While these organisms are fairly easily destroyed, Class-B allows 2 million viable coliform per gram.
These bacteria are thus able to colonize animals, including humans, through ingestion. Once
ingested, the plasmids may be transferable to normal flora, thence later to pathogenic bacteria
found in humans or animals, making later treatment with particular antibiotics ineffective. Also one
must consider transfer of genetic information from these organisms to more robust organisms.
The CDC, through its publication Emerging Infectious Diseases (Vol. 11, # 9, Sept 2005 @ p. 1389
et seq), comments on this. In that issue of EID, Sjolund et al note that resistant strains may persist
for 4 years. That resistance in the normal flora might contribute to increased resistance in higher-
grade pathogens through interspecies transfer. These authors go on to note that since
populations of the normal biota are large, multiple and different resistant variants can develop.
This thus enhances the risk for spread to populations of pathogens. Further, there is crossed
resistance. For example, vancomycin resistance may be maintained by using macrolides.
This then brings into question the current paradigm on infection and its dose response to a certain
load of a particular pathogen. Lateral transfer of mobile genetic elements conferring resistance is
not considered in this old paradigm. With the prodigious capacity for the gut bacteria to multiply,
once the lateral transfer has taken place, very small original numbers---well below the old paradigm
can be multiplied into impressive numbers. Since viruses are also involved. Their capacity to
multiply, which dwarfs that of bacteria, must also be included. Thus there is a need for a new
paradigm; unfortunately, the regulatory community seems not to recognize this.
When one considers the multiplication within sewer plants and also within their byproducts,
disbursement into the environment, the transfer to background organisms, hence to man and his
animals, then the remultiplication within commensals, the emerging picture is worrisome.
Kummerer and others have written rather extensively on the levels of antimicrobial drugs in
wastewater and wastewater products. They conclude that the levels are high enough, especially
when hospitals are connected to sewage systems, to maintain resistance.
In one paper (Clinical Microbiology & Infection, Vol 9 # 12 @ p 1203 - December 2003), Kummerer
discussed the predicted environmental concentration (PEC) for hospital effluent and for municipal
sewage. When compared both with published minimum inhibitory concentrations (MIC50) for
sensitive pathogenic bacteria the levels in the effluent exceeded the MIC50 of susceptible
pathogenic bacteria. The ratios between PEC and predicted no-effect concentrations (PNECs)
were highest for hospital effluent (in some cases 1020 times the MIC50) and frequently > 1 for
municipal sewage. PECs were found to be high enough for some compounds to have a PEC/PNEC
ratio > 1 even in surface water.
Additionally, one finds that there is a remultiplication of bacterial numbers within standing sludge,
biosolids or compost. Hassen, et al  found that, gram-positive bacteria, especially micrococcus,
spores of bacilli, and fungal propagules survived, and reached high concentrations in compost. Not
only that, "the appearance of gram-negative rods (opportunistic pathogens) during the cooling
phase may represent a serious risk for the sanitary quality of the finished product intended for
Thus, the current Part 503 limits on biosolid marker organisms may have little bearing on the
ultimate numbers. For composted sludge and its presumed equivalent to Class-A, there is again a
serious gray area.
During composting, the mesophiles (these function at normal body temperatures) can transfer
genetic information to thermophiles (these operate above the lethal fever temperatures). The
archaea, which are extreme thermophiles (these can take temperatures above the boiling point of
water), are recognized as a separate third domain of life together with the bacteria and eukarya.
Transfer of plasmids to bacteria from archaea, has been demonstrated . Thus, in theory, it may
be possible to develop a MDRB that can survive temperatures found within composting. That such
has occurred may be inferred through current studies of the passage of other genetic information
during composting. The bugs do find ways to pass-on survival enhancing genetic information.
Moving up the ladder of organisms or groups of organisms that are commonly present in sewage
sludge, one also notes the fungi, including the yeast such as a Candida species that take low to
intermediate level disinfection to kill them; the candida are gaining considerable resistance. Also, at
the intermediate-level of disinfection one notes micobacterium (tuberculosis for example and this is
also gaining resistance), the protozoa (Cryptosporidium and Giardia), additionally, there are
helminth parasites (Ascaris and Toxocara) and some of the non-enveloped viruses. So we are
already moving into a range of organisms where it is questionable whether or not the processes
used to treat sludge will destroy these groups of organisms and their genetic material.
Then finally some of the most important pathogens that are commonly in sewage sludge, the
bacterial endospoes, such as members of the Bacillus species, and a lot of the non-enveloped
viruses, norovirus is a re-naming of the Norwalk-like viruses that most people are familiar with, the
rotoviruses which are significant public health problems for diarrhea in infants and the elderly, the
Coxsackie viruses, these organisms require high level disinfection. Such high-level disinfectants
are the types used on semi-critical medical devices, endoscopes, for example. These types of
devices are likely contaminated with these organisms and standard CDC recommendations would
require high-level disinfection.
This says nothing about prions which are essentially indestructable, certainly within the range used
in either Class-B or Class-A biosolids. It has been estimated that up to 13% of the Alzheimer's
patients are actually suffering from prion disease. Multiplying out the numbers gives an impressive
figure of potential risk. Embalming currently dumps the body contents to the sewer. Thus bodies
embalmed that have died with prion disease will contribute prions to sludge.
So, the point is that when NIOSH took a look at these issues they concluded that even the
vegetative bacteria, such as salmonella and E. coli, still present a risk associated with Class B
biosolids. In the National Research Council report that came out in July of 2002 on land application
of sewage sludge, the NRC noted that the risk it posses potentially to public health. NRC made a
point out of this, i.e., that we need to see if these treatment technologies actually work and how well
they work. It also admonished EPA to look at resistance and off-site movement. We are unable to
ascertain any work in these areas by EPA. Unfortunately, the industry under regulation is not
required to gather this critical efficacy data.
The up-shot is that these processes are not even reliably destroying E. coli and the other indicator
organisms that still remain within Class B biosolids. The EPA, as noted above, still allows certain
levels of the indicator organisms to be present in the sewage sludge. That fact alone tells you that
if these vegetative bacteria are still present then you can certainly assume that microbacterium
tuberculosis, the protozoa, the parasitic worms, all of the non-envelope viruses and bacterial
spores which are far more difficult to kill are also present there in even greater numbers by virtue
of the fact that they are more difficult to kill. Again this says nothing about prions.
As noted above and elsewhere, there is a major outbreak of MRSA within the community of the
Greater Los Angeles to San Diego Basin. At least 50% of the skin infections seen within the LA
area are now MRSA. Sludge thus generated from these centers will likely contain resistant
materials, including the necessary genetic material to contaminate environmental background
systems. As noted below, EPA seems to have not studied this area, yet continues to promote the
land application of sewer sludge.
Several hospitals dealing with very sick patients dump their untreated sewage into the common
systems that currently send sludge to farm lands.This material may be top-dressed on dairy
pastureland. The animals are allowed to return after 30 days. Hospitals are epicenters for
generating antibiotic resistance. These epicenters currently dwarf the levels of resistant pathogens
and their levels of resistance as compared to the community (see study be Chitnis inserted at the
end of this paper). Nonetheless, that gap is closing. Previous studies have shown that waste
effluents from hospitals contain higher levels of antibiotic-resistant enteric bacteria than waste
effluents derived from other sources [14,15.16,17,18,19]. Again, these were studies done long ago
and yet these data are consistently ignored.
Recently, in discussing mobile genetic elements (MGE), Nielsen, et. al. [20,21], demonstrated that
DNA was well protected in dead cells and that transforming activity remained. The survival of such
material was found to be up to two years . Other papers have noted survival of genetic
information is desiccated soils for centuries. Gerba, in several papers notes that for viruses, the
survival and infectivity is extended if the viral particle is adhered to sediment. In one case he
reports on a survival of slightly more that 13 years. Since these particles can be shifted with
sediments, they can travel miles form their original site of deposit . Additionally, other papers
have demonstrated that growing plants, via their roots, could up-take and then re-transfer MGEs to
bacteria. Thus, non-pathogens and non-bacteria can serve as reservoirs for maintaining
Pneumococci, for example, can take up naked DNA from the environment (natural transformation
from lysed bacteria). Thus merely finding "dead" bacteria may be no assurance that risk has
reached acceptable levels. Further, from the classical work of Griffith, we know that pathogens can
regain virulence from dead bacteria.
Harmless gut and soil bacteria have become reservoirs for multi resistance plasmids which may be
gained from pathogens or where there are other commensals that contained the shared genetic
For example, Levy found that the resistance in gut bacteria of cattle moved to gut bacteria of mice
having access to the same area, then from the mice to pigs, chickens, and flies. He notes a Dutch
study that followed bacteria from animals to the human food chain and entered the consumer’s
kitchen. In other cited examples, he noted the distinct relationship between MDRB in animals and
thence to humans attending them, even though the humans used no antibiotics or ate the animals.
Levy’s work is not new. (Levy SB, MD. The Antibiotic Paradox. New York, Plenum Press 1997).
Thus the current U.S. EPA Class-B biosolids with its allowed fecal coliform counts of 2 X10/6 per
gram may actually constitute a large aliquot when containing MDRB and applied to areas with
animal or vector access. These bacteria are thus able to colonize animals, including humans,
through ingestion. There are indications within the literature of E. coli O157:H7 being to travel up
the vascular system in lettuce . Since lettuce is eaten raw, the risk should be clear to most
readers. Once ingested, the shiga containing plasmids may be transferable to normal flora, thence
later to pathogenic bacteria found in humans or animals, making later treatment with particular
antibiotics ineffective. Additionally, one finds that there is a remultiplication of bacterial numbers
within standing sludge, biosolids or compost (see Hassen). Thus, the current Part 503 limits on
biosolid marker organisms may have little bearing on the ultimate numbers.
Further, assuming the movement of genetic information to gut bacteria, health standards set on
presumed infective doses may have little relevance. With the prodigious capacity of the gut
bacteria to multiply, the former paradigms are of little value.
With the apparent lack of information within EPA on antibiotic resistance, this also raises serious
doubts about Class-A and composted Class-B’s equivalent for Class-A. The risks are too great to
allow the continued application of Los Angeles area sewer sludge and its products within Kern
It was assumed for a long time that gene transfer between different species of microorganisms is a
very rare event at best; that view has changed. The available evidence suggests that interspecific
transfer of genes has occurred between the three major groups of organisms: archaebacteria,
eubacteria and eukaryotes. There is very strong evidence that gene transfer easily occurs
between distantly related bacteria. Marcinek, et al  estimated that under the natural conditions
of a sewer treatment works, between 10 to the 6th though 10 to the 9th gene transfer events
between different E. faecalis strains should take place per day. The maximum number of transfer
events for the sex pheromone plasmids between different strains of E. faecalis in the municipal
sewage water treatment plant was found to range from 10 to the 5th through 10 to the 8th events
per 4 hour period [since different computer programs seem to drop superscript, numerical
indicators are thus indicated] . This w!
ork also indicated that gene transfer should take place under natural conditions following release
of sewer effluent.
Iversen, et al,  isolated VRE in 21 of 35 untreated sewage samples (60%), from 5 of 14 hospital
sewage samples (36%), from 6 of 32 treated sewage samples (19%), and from 1 of 37 surface
water samples. It was speculated that antimicrobial drugs or chemicals released into the sewage
system sustained VRE in the system. Others  have demonstrated direct evidence that related
tetracycline resistance-encoding plasmids have disseminated between different Aeromonas spp.
and E. coli and between the human and aquaculture environments in distinct geographical
locations. Collectively, these findings provide evidence to support the hypothesis that the aquatic
and human compartments of the environment behave as a single interactive niche.
Ribeiro  and others  have found that as these organisms progress further through sewer
treatment, the level of resistance and number of transferred plasmids increases. Reinthaler et al
 found that the highest resistance rates were found in E. coli strains of a sewage treatment
plant which treats not only municipal sewage but also sewage from a hospital. Thus, these authors
concluded that sewage treatment processes contribute to the dissemination of resistant bacteria in
Cenci, et al  reviewed the incidence and the patterns of the antibiotic and metal resistance in
106 strains of Escherichia coli isolated from ground waters, used also as drinking water supply.
These organisms were studied in comparison with the resistance behavior in the 104 strains of the
same microorganism isolated from non hospitalized patients. When, however, these were
compared to hospitalized patients, the patterns of the antibiotic multiresistances and the strains
isolated from patients and from ground waters did not differ greatly. The authors concluded that
their findings strengthened the hypothesis that resistance to antibiotics had been acquired by
Escherichia coli strains before reaching the ground waters.
In Kern County, California, which is attempting to ban land application of sewer sludge, those
concerned over contamination of aquifers have adequate grounds for their concerns. The politics
and pressures involved are considerable. Kern is a politically under represented area compared to
the more populous
Los Angeles, and other southern counties of California. The majority of sewer sludge produced in
Southern California has been destined for Kern County as a dumping ground. One of the area’s
major aquifers underlies Kern County lands, lands currently receiving thousands of tons of sewage
sludge. Many of the industrial pollutants within the Southern California sewage are able to select
for resistance. Also, the pH can be driven down to levels that aluminum is released. Nonetheless, it
appears that public health issues are ignored or at least under played.
Others  have noted that the mere process of chlorinating effluent tends not only to increase
resistance, but also increase the competitive edge of these survivors. Thus, we are now seeing
developing resistance to chlorine, other antiseptics, and disinfectants. This then raises issues of
abstracting contaminated ground water and whether or not current water quality standards, which
now do not consider antibiotic resistance, are actually fully protective of human health. Certainly
return flows from irrigated pastures and irrigation do not consider off-site movement of resistance.
The topic is not even considered. Nor for that matter is antibiotic resistance considered by the
California Integrated Solid Waste Board for its rules on compost.
Chlorine resistance also raises a curious aside and academic question. If the bugs are resistant to
chlorine, how does this impact the immune system's use of hypochlorite bursts within leukocytes?
Thus, those agencies responsible for assuring public health have not considered these areas of
risk nor have the standards been brought up to date, yet the literature on the subject is not
obscure or new. All agencies mentioned above had been apprised of these risks earlier in the
decade, yet all such agencies refuse to seriously deal with this issue. The standards are seriously
out of date.
The workers at composting and sewer plants are also at risk. Several papers [34,35,36] have
reported on transfer of viral particles and bacteria in aerosols that are generated by and surround
many of these plants. In addition, there are studies on wind drift of these plumes into the
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 Linton, K. B., M. H. Richmond, R. Bevan, and W. A. Gillespie. 1974. Antibiotic resistance and R
factors in coliform bacilli isolated from hospital and domestic sewage. J. Med. Microbiol. 7:91-103.
 Walter, M. V., and J. W. Vennes. 1985. Occurrence of multiple-antibiotic-resistant enteric
bacteria in domestic sewage and oxidation lagoons. Appl. Environ. Microbiol. 50:930-933.
 Rhodes G, Huys G, Swings J, McGann P, Hiney M, Smith P, Pickup RW. Distribution of
oxytetracycline resistance plasmids between aeromonads in hospital and aquaculture
environments: implication of Tn1721 in dissemination of the tetracycline resistance determinant tet
A. Appl Environ Microbiol 2000 Sep;66(9):3883-90.
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purified city sewers in the spread of antibiotic-resistant bacteria of the Enterobacteriaceae family]
Med Dosw Mikrobiol 1989;41(2):100-5.
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BD413 with cell lysates of Acinrtobacter sp, Pseudomonas fluorescens, abd Burkholderia cepacai
in soil microcosoms. Sappl Environ Microbiol 2000 :66,206-12.
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gene transfer from transgenic plants to soil bacterium Acinetobacter calcoaceticus in soil
microcosms. Theor Appl Genet 1997:95, 815-21.
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DNA. Appl Environ Microbiol 1999 :4, 1550-54.
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sediments down stream from a sewage outfall in the Taieri River, Otago. New Zealand Journal of
Marine and Freshwater Research, 1986, Vol.20: 101-105
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Tobacco Plants to Bacteria. Applied and Environmental Microbiology, July 2002, p. 3345-3351, Vol.
68, No. 7
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Reviews in Medical Microbiology. 13(1):15-27, January 2002.
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Enterohemorrhagic Escherichia coli O157:H7 and Competition by Enterobacter asburiae Applied
and Environmental Microbiology, August 2003, p. 4915-4926, Vol. 69, No. 8.
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under natural conditions in municipal sewage water treatment plants. Appl Environ Microbiol 1998
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in Swedish sewage. Appl Environ Microbiol 2002 Jun;68(6):2838-42.
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Antibiotic resistance of E. coli in sewage and sludge. Water Res 2003 Apr;37(8):1685-90.
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My group, not the original panel, had requested via Freedom of Information Act, certain data from
the U.S. EPA on their progress dealing with biosolids and resistance. The EPA response was to
merely directed us to a section of the NERL’s website, which contained no usable information. This
site was (www.epa.gov/nerlesd1/chemistry/pharma/fq.htm#disposal), as evidenced by the following
search results. Similar results were found for other EPA web addresses.
Results of Searching the "Environmental Sciences" Area of EPA's Web Site
No matches found for transposon; 1402 files searched
No matches found for antibiotic resistance + biosolids; 1402 files searched.
No matches found for antimicrobial resistance + biosolids; 1402 files searched
No matches found for virulent pathogens + biosolids; 1402 files searched.
No matches found for plasmids + biosolids; 1402 files searched.
No matches found for mobile genetic elements; 1402 files searched.
No matches found for high level disinfection + biosolids; 1402 files searched.
Results of Searching EPA's Entire Web Site
We have searched the entire EPA site and found the following results. You may also return to
searching for the same terms within Environmental Sciences.
No matches found for high level disinfection + biosolids; 494732 files searched.
No matches found for plasmids + biosolids; 494732 files searched.
No matches found for transposons + biosolids; 494732 files searched.
No matches found for mobile genetic elements + biosolids; 494732 files searched.
No matches found for virulent pathogens + biosolids; 494732 files searched.
No matches found for antibiotic resistance + biosolids; 494732 files searched.
No matches found for antimicrobial resistance + biosolids; 494732 files searched.
Results of Searching the "Exposure Research" Area of EPA's Web Site
We have searched the area of EPA's site related to Exposure Research and found the following
results. You may also search for the same terms across EPA's entire site.
No matches found for prions + biosolids; 3352 files searched.
Results of Searching EPA's Entire Web Site
We have searched the entire EPA site and found the following results. You may also return to
searching for the same terms within Exposure Research.
No matches found for prions + biosolids; 530969 files searched.
Received 5 February 2000; revised accepted 28 July 2000
Hospital effluent: A source of multiple
V. Chitnis, D. Chitnis*,†, S. Patil** and Ravi Kant*
*Department of Pathology, Choithram Hospital and Research Centre,
Manik Bagh Road, Indore 452 001, India
**School of Life Sciences, Devi Ahiyla University, Indore 452 001,
The present work was carried out to study the spread
of multiple drug-resistant (MDR) bacteria from hospital
effluent to the municipal sewage system. The MDR
bacteria population in hospital effluents ranged from
0.58 to 40% for ten hospitals studied while it was less
than 0.00002 to 0.025% for 11 sewage samples from
the residential areas. Further, the MDR bacteria
carried simultaneous resistance for most of the commonly
used antibiotics and obviously the spread of
such MDR bacteria to the community is a matter of
Water Intelligence Online © IWA Publishing 2003
A Dynamic Model to Assess Microbial Health Risks Associated with Beneficial Uses of Biosolids -
John M. Colford*, Jr, Don M. Eisenberg**, Joseph N.S. Eisenberg*, James Scott* and Jeffrey A.
*School of Public Health, University of California, Berkeley, USA
**Eisenberg, Olivieri and Associates, Inc, USA
Maximum allowable levels for chemical contaminants in biosolids were developed for the Part 503
rule using risk-based methodologies. However, maximum allowable levels of microbiological
contaminants in the Part 503 rule were based on specific treatment methodologies rather than risk
levels, because it was determined at that time that risk assessment methodologies were not
sufficiently developed. Given the current interest in the beneficial uses of biosolids and the
projected rapid growth of biosolids reuse, there is increasing interest in the development of a
microbial risk assessment methodology for regulatory and operational decision making.
This document presents a methodology for assessing risks to human health from pathogens via
exposure to biosolids. The methodology integrates two fundamental components: an exposure
assessment component and a health risk component. The exposure assessment component is
used to quantify pathogen levels in the environment and serves as input to the health effects
component. The health effects component is used to quantify health risks using a model that
explicitly accounts for properties unique to an infectious disease process, specifically secondary
transmission and immunity.
To demonstrate the applicability of these risk-based methods developed for biosolids exposure,
numerical simulations were carried out for a case study example in which the route of exposure was
direct consumption of biosolids-amended soil. [McGowan's comment interjected---what about
respiratory?]The output from the case study yielded a decision tree that differentiates between
conditions in which the risk from biosolids exposure is high and those conditions in which the
relative risk from biosolids is low. This decision tree illustrates the interaction among the important
factors in quantifying risk. For the case study example, those factors include biosolids treatment
processes, the pathogen shedding rate of infectious individuals, secondary transmission and
immunity. Further work in determining biosolids exposures is required before this methodology can
be used in a comprehensive risk assessment.
McGowan's final comment---where is the potential for transfer of antibiotic resistance from a very
small number to the gut bacteria and then its (the gut bacteria's) prodigious capacity to multiply
that information? Thus their whole study---absent this aspect is badly flawed. Reliance on this
study would then vastly underestimate the real risks. ---See: Maria Sjölund's paper below indicating
a long-standing ability for these bacteria to remain in the gut .
"resistant strain may persist for 4 years, in the absence of further antimicrobial treatment."
Also, for example, Levy found that the resistance in gut bacteria of cattle moved to gut bacteria of
mice having access to the same area, then from the mice to pigs, chickens, and flies. He notes a
Dutch study that followed bacteria from animals to the human food chain and entered the
consumer’s kitchen. In other cited examples, he noted the distinct relationship between MDRB in
animals and thence to humans attending them, even though the humans used no antibiotics or ate
the animals. Levy’s work is not new. (Levy SB, MD. The Antibiotic Paradox. New York, Plenum
Press 1997). Rusin and Gerba have written on the transfer of pathogens from common household
surfaces via finger to mouth. Others have discussed dust as a carrier of viable pathogens. Gerba
has written extensively on the movement of pathogens in sediment, their protection for long periods
within sediments and the re-transport of viable pathogens. The NRC in its 2002 report admonished
EPA to look at off-site movement !
and resistance. There is no evidence that this re-analysis has taken place, yet the World Health
Organization has raised the subject of resistance to a Global crisis.
Water Intelligence Online © IWA Publishing 2002
A risk assessment of emerging pathogens of concern in the land application of biosolids
G. Gerba: [University of Arizona, Department of Soil, Water, and Environmental Science, Tucson,
AZ 85721, USA]
L. Whitehead III
ABSTRACTA RISK ANALYSIS WAS PERFORMED TO ASSESS WHICH EMERGING PATHOGENS
WOULD BE MOST LIKELY TO SURVIVE TREATMENT REQIRED FOR Class B biosolids before
land application. A risk model was used to assess the risk of infection and illness from enteric
viruses after application of Class B biosolids.
McGowan's comment--again, antimicrobial resistance is not considered and accordingly, this study
is badly flawed.
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