United States
Environmental Protection
Agency
Health Effects Research
Laboratory
Research Triangle Park NC 27711
Research and Development
EPA-600/S1-84-014 Nov. 1984
4>EPA Project Summary
Evaluation of Health Risks
Associated with Wastewater
Treatment and Sludge
Composting
C. S. Clark, H. S. Bjornson, C. C. Linnemann, Jr., and P. S. Gartside
The risks to human health from ex-
posures to biological and chemical
agents in waste materials are a primary
motivating factor for improving the
practices for storing, transporting, treat-
ing and ultimately disposing these
wastes. Four areas of research of poten-
tial health effects related to waste expo-
sures from wastewater treatment plant
sludge composting, municipal waste-
water treatment, and toxic waste dump
leachate, were undertaken under this
Cooperative Agreement. The specific
areas were: (1) a prospective health
study of workers engaged in the com-
posting of wastewater treatment plant
sludge, (2) serologic analyses of inex-
perienced and experienced wastewater-
exposed workers, (3) a mortality study
of former employees of a large waste-
water treatment system, and (4) select-
ed chemical analyses of biological spec-
imens from a population whose drinking
water had been contaminated with
leachate from a pesticide waste dump.
Each of these studies had its origins in
previous research efforts, the results of
which have been reported elsewhere.
The study involved compost workers
at compost sites in Camden, NJ,
Philadelphia, PA, Beltsville, MD, and
Washington, DC, and control groups.
Physical examinations of the workers
showed an excess of abnormal skin,
nose, and ear conditions. In addition,
several of the laboratory tests were
suggestive of low-grade inflammatory
response. Viable units of the fungus
Aspergillus fumigatus were frequently
detected in cultures of throat and nasal
swabs of compost workers and were
rarely detected in workers with little or
no compost exposure. The effects ob-
served in the compost worker study
may be due to the nature of the compost
process itself and therefore may not be
related specifically to the use of waste-
water sludge in the composting opera-
tions. However, they do justify a
continuation of health studies of
workers engaged in the composting of
waste materials. The fact that sludge
composting has been practiced for a
relatively short period of time adds to
the need for additional study.
Using a serum bank established in an
earlier study of wastewater workers
and controls in Cincinnati, OH, Chicago,
IL, and Memphis, TN, the present study
evaluated possible viral factors that may
be included in the previously detected
excess in gastrointestinal illness ob-
served among workers during their first
two years of wastewater employment.
Testing for antibody to Hepatitis A
(anti-HAV) virus was among the other
tests performed. Analysis of paired sera
from workers who reported gastroin-
testinal illness indicated that among
inexperienced workers, Norwalk agent
was associated temporally with 13% of
these illnesses. Inexperienced waste-
water-exposed workers had higher
levels of antibody to Norwalk agent
than did experienced and control
workers (p - 0.03). The presence of
anti-HAV was not different among the
inexperienced wastewater workers.
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experienced wastewater workers, and
controls, and was not associated with
length of wastewater exposure for the
exposed wastewater workers. H owever,
anti-HAV was found to be associated
with race (p < 0.0001) and age (p <
0.001).
An analysis of 815 death certificates
from former workers at the Metropol-
itan Sanitary District of Greater Chicago
revealed that for a relatively rare cause
of death, leukemia (1 in 134), the
proportion of workers with this cause of
death was about twice as many as
expected (11 observed, 6 expected: p =
.04). For another relatively rare cause of
death, cancer of the esophagus (1 in
215) there was also about twice as
many observed as expected deaths
which was almost significant using U.S.
Vital Statistics (p = 0.08) but not using
Illinois Vital Statistics (p = 0.13). A
more common cause of death, pneu-
monia (1 in 41), less than one-half as
many deaths as expected were observed
(p = 0.02). Recommendations for fur-
ther study are made.
A previous study of a population
whose drinking water had been heavily
contaminated with leachate from a
pesticide waste dump had revealed
higher levels of several liver function
tests and enlarged livers among the
exposed population. In the present
study, specimens available from the
earlier study were examined to deter-
mine if specific contaminants could be
detected in the serum or if an overall
indication of chemical exposure, urinary
thioether concentrations, was elevated.
Analysis for volatile organic chemicals
in serum from individuals whose drink-
ing water had previously been contami-
nated did not reveal higher levels when
compared with results from specimens
from non-exposed individuals. Concen-
trations of thioethers in urine specimens
were not found to be significantly higher
in specimens from workers at a wastewater
treatment plant receiving wastes from a
pesticide manufacturer, than in those
from a control plant and were also not
significantly higher in individuals prev-
iously exposed to chemically-contam-
inated drinking water than in controls.
This Project Summary was developed
by EPA's Health Effects Research Labo-
ratory, Research Triangle Park, NC. to
announce key findings of the research
project that is fully documented in a
separate report of the same title (see
Project Report ordering information at
back).
Introduction
The risks to human health from ex-
posures to biological and chemical agents
in waste materials are a primary motivat-
ing factor for the improvement in practices
for storing, transporting, treating, and
ultimately disposing of these wastes. Four
areas of research of potential health
effects related to waste exposures from
wastewater treatment plant sludge com-
posting, municipal wastewater treatment,
and toxic waste dump leachate were
undertaken under this Cooperative Agree-
ment. The specific areas were: (1) a
prospective health study of workers en-
gaged in the composting of wastewater
treatment plant sludge, (2) serologic
analyses of inexperienced and experi-
enced wastewater-exposed workers, (3) a
mortality study of former employees of a
large wastewater treatment system, and
(4) selected chemical analyses of bio-
logical specimens from a population
whose drinking water had been contam-
inated with leachate from a pesticide
waste dump. Each of these studies had its
origins in previous research undertak-
ings, the results of which have been
reported elsewhere. The compost workers
study and the mortality studies were a
continuation and an expansion, respec-
tively, of earlier studies. The other two
projects made use of serum and urine
available from previously-completed stud-
ies.
The ultimate disposition of the residuals
resulting from the treatment of municipal
wastewaters, i.e., sludges, has been a
major problem facing many municipal-
ities. Legislation which prohibited ocean
dumping of sludge after 1981 has forced
many municipalities to develop alterna-
tive disposal methods. One option which
has been considered is the application of
wastewater and sludge to the land for
crop irrigation or as an organic soil
amendment. The composting of sewage
sludge has been shown to yield a product
which appears to be biologically safe and
well suited for ultimate land disposal. The
composting of wastewater treatment
plant sludge has increased considerably
in the past several years in the U.S. and
elsewhere. As recently as ten years ago
sludge composting in the U.S. was prac-
ticed mainly by Los Angeles County,
using the windrow method. The develop-
ment of the aerated pile method by the
U.S. Department of Agriculture at Belts-
ville, MD, prohibitions against ocean
dumping, and the increased cost of
alternative sludge treatment methods
have led to a rapid expansion in systems
for composting sludge prior to its lane
application.
Successful year-round outdoor com
posting sites are operating in many area;
of the Northeast and Midwest. Currently
Philadelphia, PA, Camden, NJ, Washing
ton, DC, Columbus, OH, Windsor, Ontario
Bangor and Portland, ME, aswellasothe
smaller cities, have initiated composting
of municipal sludge by the aerated pill
method. Although the numbers of patho
genie bacteria and viruses are effective!'
reduced by the high temperatures
achieved in composting, conditions an
ideal for the growth of thermophilii
microorganisms, such as the fungui
Aspergillus fumigatus. Therefore, work
ers directly associated with the compost
ing process will be exposed to higl
concentrations of microorganisms; no
only those microorganisms present in thi
raw sludge, but also those which pro
liferate during the composting process
such as Aspergillus fumigatus. The dus
at composting sites has also been showi
to contain significant quantities of lipo
polysaccharide (LPS) derived from viabli
and non-viable gram-negative microorga
nisms which are present in sludge. Work
ers at composting sites are exposed t
potential human pathogens, bacterie
endotoxins, and other microbial toxins vi
inhalation of dust generated by manipula
tion of the compost piles and by inao
vertent ingestion of compost or sludge
through dirtying of the hands or face wit
compost or sludge and subsequent trans
port to the mouth. The compost worker
study included in the Cooperative Agree
ment has focussed on an evaluation c
the health effects of chronic, long-terr
exposure of workers at composting faci
ities to the combination of microbit
pathogens, microbial toxins, and LPi
present in the work environment £
composting sites.
The potential health effects of exposur
to municipal wastewater treatment proc
esses are not only important to th
workers at these plants and ultimately t
designers of these plants and other
involved in their construction, financin
and regulations, but also to communitie
that are neighbors to existing and futur
plants. An infectious disease study <
municipal wastewater treatment plant
in Cincinnati, OH, Chicago, IL, and Merr
phis, TN, concluded that although n
evidence was found to support the e>
istence of any significant health effects <
occupational exposure to viruses i
wastewater, an excess of reports i
gastrointestinal illnesses was detecte
among the inexperienced wastewate
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exposed workers. Also, several recom-
mendations for additional studies were
made to aid in the interpretation of the
results. These recommendations have
been carried out under this Cooperative
Agreement.
Another approach to determine health
effects of occupational exposu re to waste-
water treatment operations is a study of
the causes of death of former employees
in wastewater treatment systems. An
interim report on such a study was
presented by the authors at a 1 979 EPA
symposium. The interim report of former
employees of the Metropolitan Sanitary
District of Greater Chicago did not indi-
cate any excesses of any of the major
causes of death. This mortality study was
expanded under the present Cooperative
Agreement to include twice as many
decedents and to include more detail on
causes of death and to examine the
relationship between cause of death and
various aspects of employment history.
Human health risks from improper
disposal of toxic wastes has become an
increasingly important issue in recent
years. A study of the health effects on a
rural community in western Tennessee
from leachate from a pesticide waste
dump was conducted under a previous
U.S. EPA grant. In the Hardeman County
study we detected abnormalities in certain
liver function tests and in excess of people
with enlarged livers in the exposed popu-
lation when compared to controls. Ex-
posure was well-documented by means
of water analyses by various public
agencies and by limited air sampling that
we had conducted. However, only limited
biological monitoring was included in the
previous study and the emphasis was on
compounds we were investigating else-
where and not on the more abundant
compounds in the contaminated well
water. Under the present Cooperative
Agreement, additional biological monitor-
ing was undertaken on the Hardeman
County population and on a wastewater
worker population exposed to the same
wastes. Some of this research was per-
formed under a U.S. EPA Cooperative
Agreement at the University of Miami,
Florida.
Conclusions
1. Physical examinations of the work-
ers participating in this study re-
vealed an increased incidence of
the following abnormal findings in
compost and intermediate-exposed
workers: acute and/or chronic in-
flammation or infection of the skin.
evidence of acute and/or chronic
inflammation of the nasal mucosa
and eyes, and evidence of acute and
chronic infections of the ear. The
high prevalence of these findings in
compost and intermediate-exposed
workers and not in the controls
suggests that they may be related to
compost exposure.
2. The presence of an occupational
pulmonary disease was detected on
the chest X-ray in one worker with
four years exposure to composting.
Duetothesmall number of workers
with > 3 years work exposure in the
study, this may be very significant.
3. Compost workers had no evidence
of abnormalities of liver or renal
function during the study period.
4. Hemolytic complement (CH5o) liters
and white blood cell counts were
elevated in compost workers as
compared to controls; the elevations
were not observed during all sam-
pling periods and may have been
related to seasonal variations in
exposure conditions at the compost
sites. Concentrations of C3 and C-
reactive protein were similar among
all exposure groups.
5. There was no correlation of serum
concentrations of the immunoglob-
ulins G, M, A, and E by worker
exposure group.
6. Compost workers appear to have
higher levels of IgG antibody against
compost-derived lipopolysaccha-
ride.
7. Compost exposure does not seem
to have a consistent effect on levels
of IgG antibody against A. fumi-
gatus.
8. Extremely high numbers of A. fumi-
gatus and other thermophilic fungi
were detected in the environment
at the compost sites studied; both
total and respirable numbers were
significantly above expected back-
ground levels. Highest concentra-
tion of fungi were detected down-
wind from active compost sites.
9. Cultures of the throat and anterior
nares of workers at compost sites
were frequently positive for Asper-
gillus fumigatus; similar cultures
obtained from workers in the inter-
mediate-exposed and control groups
(exposure groups II and III) were
almost always negative for/4, fumi-
gatus. These results demonstrate
that exposure of workers to high
concentrations of fungal spores in
the work environment results in
viable colony forming units of the
fungi being routinely present in the
upper respiratory tract.
10. All workers screened lacked precip-
itating antibodies to the following
antigens: H and M antigens of
Histoplasma capsulatum; and a
pool of antigens prepared from A.
fumigatus, A. flavus, A. carneus,
and A. niger. These results suggest
that infection caused by these fungi
were uncommon among the work-
ers studied, despite exposure of
workers at compost facilities to
extremely high numbers of fungal
spores.
11. Seroconversionsto/.es7'o/7e//ap/7eiy-
mophila were more common in
study participants in the Camden-
Philadelphia areathan inthe Wash-
ington, DC metropolitan area. How-
ever, there was no evidence of
increased risk of infection in com-
post-exposed workers caused by
this organism suggesting that ex-
posure toLegionella species is not a
risk of sludge compost employment.
12. There appears to be a pattern of
increased numbers of symptoms of
skin irritation and burning eyes
among compost-exposed workers
compared to those non-exposed
during the fall and winter seasons.
13. Wastewater-exposed workers in
the study do not appear to be at
increased risk to infection with
hepatitis A. Antibody to hepatitis A
was found to be more prevalent in
black workers than in white workers
and was positively associated with
age.
14. In Cincinnati, an apparent infection
with Echovirus 3, which had prev-
iously been suspected on the basis
of isolation of the virus from throat
and rectal swabs, was serologically
detected in inexperienced sewage-
exposed workers. An infection with
Echovirus 6, detected by a previous
study through rising titer levels
from January-October 1977, was
apparently preceded by an infection
in 1976 as evidenced by higher
antibody prevalence but not by
statistically higher titer level rises.
15. About 13% of the gastroenteritis
reported by inexperienced sewage-
exposed workers appears to be
associated with Norwalk agent.
Infection with Norwalk agent ap-
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pears to be a risk of the first two
years of exposure to wastewater
and it may also be associated with
level of biological aerosol exposure.
16. Antibody to the alga prototheca
does not appear to be consistently
higher among wastewater-exposed
workers than control groups.
17. An analysis of 815 death certif-
icates from workers in a waste-
water treatment system revealed
that for a relatively rare cause of
death, leukemia (1 in 134), the
proportion of workers with this
cause of death was about twice as
many as expected (11 observed, 6
expected: p = .04). For another
relatively rare cause of death, can-
cer of the esophagus (1 in 215)
there was also about twice as many
observed as expected deaths which
was almost significant using U.S.
Vital Statistics (p = 0.08) but not
using Illinois Vital Statistics (p =
0.13). For a more common cause of
death, pneumonia (1 in 41), less
than one-half as many deaths as
expected were observed (p = 0.02).
18. Analysis for volatile organic chem-
icals in serum from individuals
whose drinking water had previous-
ly been contaminated by a pesticide
waste dump did not reveal higher
levels when compared with results
from specimens from non-exposed
individuals.
19. Concentrations of thioethers in
urine specimens were not found to
be significantly higher in specimens
from workers at a wastewater treat-
ment plant receiving wastes from a
pesticide manufacturer, than in
those from a control plant and were
also not significantly higher in
individuals previously exposed to
chemically-contaminated drinking
water than in controls.
Recommendations
1. Physical examinations should be
conducted on as many of the orig-
inal compost study participants as
possible and on additional compost
workers to determine if the abnor-
mal findings evident in this study
regarding skin, nose, ears, and eyes
can be confirmed. These examina-
tions should include: cultures of
anterior nares and oropharyngeal
swabs, complete blood count with
differential, serum gamma glutamic
transaminase, ELISA-determined
4
IgG antibody against compost-de-
rived LPS, CH50, and IgE.
2. Investigations should be conducted
of the long-term effects of exposure
to composting on the pulmonary
system; the testing should include
pulmonary function testing, chest
X-ray, and physical exam.
3. It is important to determine whether
individuals with chronic diseases
such as diabetes, chronic pulmon-
ary disease, allergic disorders, etc.
are at greater risk of developing
abnormalities during exposure to
composting.
Testing for these individuals:
pulmonary function testing
chest X-rays
physical examinations
history and illness monitoring
Optional tests
complete blood counts
erythrocyte sedimentation
rates: index of ongoing in-
flammatory response
liver and renal function tests
determination of antibody to
LPS and A. fumigatus anti-
gens.
4. In order to gain further insight into
the etiology of gastroenteritis
among wastewater workers, sera
collected before and after such
episodes, along with rectal swabs
and stool collected during the acute
phase of the illness, should be
analyzed to determine the agents
involved. Norwalk agent and related
viruses and toxigenic or invasive E.
coli should be included in the
serologic testing. Swabs and stool
should be examined for the pres-
ence of bacteria, viruses and para-
sites.
5. In ordertodetermine if the apparent
excess of leukemia deaths persists
in a larger population, the Mortality
Study of Chicago Metropolitan
Sanitary District Workers (MSD)
should be expanded by: (1) analysis
of 1960-76 decedents not included
in the present study, (2) extension
of the study to include 1977-1982
decedents, and (3) extension of the
study to include all MSD decedents
prior to 1960.
6. A mortality study of wastewater
workers in another metropolitan
area should be initiated to deter-
mine if an excess of deaths by
leukemia has occurred in othei
wastewater worker populations.
7. Sincethetestfor urinary thioethen
appears to be potentially useful as <
biological indicator of chemica
exposure, it should be utilized ir
studies of other populations ex
posed to chemical wastes.
U. S. GOVERNMENT PRINTING OFFICE: 1984/559-111/10735
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C. S. Clark, H. S. Bjornson, C. C. Linnemann, Jr., and P. S. Cart side are with
University of Cincinnati, Cincinnati, OH 45267.
Walter Jakubowski is the EPA Project Officer (see below).
The complete report, entitled "Evaluation of Health Risks Associated with
Wastewater Treatment and Sludge Composting," fOrder No. PB 85-115 889;
Cost: $23.50, subject to change) will be available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Health Effects Research Laboratory
U.S. Environmental Protection Agency
Research Triangle Park, NC 27711
United States
Environmental Protection
Agency
Center for Environmental Research
Information
Cincinnati OH 45268
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