MUNICIPAL WASTEWATER SLUDGE
HEALTH EFFECTS RESEARCH
PLANNING WORKSHOP
January 10-12, 1984
U.S. Environmental Protection Agency
Andrew Breidenbach Research Center
Cincinnati, Ohio
Prepared by:
Eastern Research Group, Inc.
185 Alewife Brook Parkway
Cambridge, MA 02138
617-661-3111
-------
27920
MUNICIPAL WASTEWATER SLUDGE
HEALTH EFFECTS RESEARCH
PLANNING WORKSHOP
January 10-12, 1984
U.S. Environmental Protection Agency
Andrew Breidenbach Research Center
Cincinnati, Ohio
Prepared by:
Eastern Research Group, Inc.
185 Alewife Brook Parkway
Cambridge, MA 02138
617-661-3111
-------
TABLE OF CONTENTS
Page
SECTION I INTRODUCTION 1-1
SECTION II MICROBIOLOGICAL HEALTH EFFECTS OF
MUNICIPAL WASTEWATER SLUDGE DISPOSAL
Session Summary 2-1
Quantity, Quality, and Mode of Current and
Projected Sludge Disposal. Robert K. Bastian,
OWPO/EPA 2-5
The Establishment of a Regulation for Control
of Pathogens in Sludge Applied to Land.
Joseph B. Farrell, HERL/WRD/EPA 2-14
Wastewater Sludge Microbiological Health
Effects and Risk Assessment. Sydney Munger,
Seattle Metro 2-19
Sludge Microbiological Health Effects; The
Epidemiological Approach. Bernard P. Sagik,
Drexel University 2-26
Alternative Approaches to Microbiological
Risk Assessment. Charles A. Sorber,
University of Texas at Austin 2-33
Microbiological Risk Assessment of Sludges;
Data Reguired by EPA. Sheila L. Rosenthal,
OH EA/EPA 2-40
Organization, Responsibilities, Viewpoints,
and Perspectives on Pathogen Controls.
Charles S. Spooner, OW/EPA 2-44
i
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TABLE OF CONTENTS (CONT.)
Page
Assessing Potential Health Effects of Land-
Applied Sewage Sludge. Rufus L. Chaney, USDA...2-47
Summary of the Discussion Session On the
Microbiological Health Effects of Sludge
Disposal. Walter Jakubowski, HERL/EPA 2-55
Recommendations for Municipal Wastewater
Sludge Health Effects Research: Microbiology.
Walter Jakubowski, HERL/EPA 2-58
SECTION III ORGANIC CHEMICAL HEALTH EFFECTS
OF MUNICIPAL WASTEWATER SLUDGE
DISPOSAL
Session Summary 3-1
Status Report on Toxic Organics of Concern
in Sewage Sludges. Charles S. Spooner, OW/EPA..3-4
Types and Concentrations of Organics in
Municipal Sludge. Lee W. Jacobs, Michigan
State University 3-12
Transfer of Synthetic Organics from Sludge
to Soil. Lewis M. Nay lor and Raymond C. Loehr,
Cornell University 3-22
Stability, Mobility, and Bioactivity of
Organics in Soil. Jerry B. Weber, Harry J. Strek,
and Michael R. Overcash, North Carolina State
Un ive rs ity 3-3 0
Toxicological Studies for the Assessment of
Risk Associated with Municipal Sludge.
John G. Babish, Cornell University 3-38
ii
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TABLE OF CONTENTS (CONT.)
Page
The Use of Mutagenicity Data for Assessing
Municipal Sludge. Michael J. Plewa and
Philip K. Hopke, University of Illinois 3-43
Approaches to the Fractionation and Identi-
fication of Mutagens in Municipal Sludge.
M. Wilson Tabor, University of Cincinnati 3-47
Health Effects of Organic Priority Pollutants
in Wastewater Sludge — A Risk Assessment.
Sydney Munger, Seattle Metro 3-54
Summary on the Discussion from the Workshop
on Organic Chemicals in Sludge. F. Bernard
Daniel, HERL/EPA 3-63
APPENDIX A WORKSHOP PARTICIPANTS AND
OBSERVERS A-l
APPENDIX B WORKSHOP AGENDA B-l
APPENDIX C LIST OF ACRONYMS AND ABBREVIATIONS... .C-l
i i i
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SECTION I
INTRODUCTION
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Workshop Background
Several major environmental laws and Federal regulations
directly relate to sludge management health concerns. One
set of these regulations was issued in 1979 as an interim
final criteria for sludge disposal, in response to Section
405 of the Clean Water Act and Subtitle D of the Resource
Conservation and Recovery Act. The U.S. Environmental
Protection Agency (EPA) has thus had an increasing involve-
ment in sludge management during the past several years.
This involvement was highlighted in Fiscal Year 1983 by the
activities and interim report of the Agency-wide Sludge Task
Force and a major Workshop on Utilization of Municipal
Wastewater and Sludge on Land, held in Denver, Colorado,
in February 1983.
One outgrowth of the Denver meeting was the development
of a 3-day workshop that would have a two-fold purpose:
1. To examine the status of research and risk
estimation related to the health effects of
municipal wastewater sludge diposal.
2. To clarify exactly what information the EPA
needs now and will need in the near future to
enable it to carry out its regulatory responsi-
bilities in sludge management.
That workshop was held on January 10 through 12, 1984
at the EPA's Andrew Breidenbach Research Center in Cincinnati,
Ohio. [jThe attendees focused their discussions on the research,
risk estimation, and regulatory data needs concerning the
microbiological and organic chemical contaminants of municipal
wastewater sludge as related to disposal ogitions and their
potential for causing human health etfectsVj Walter Jakubowski
of the EPA's Health Effects Research Laboratory (HERL) in
Cincinnati chaired the Microbiology Session, and F. Bernard
Daniel, also of HERL, chaired the Organic Chemical Session.
The attendees included staff from all EPA offices
involved with municipal sludge policy, regulation, and
research; representatives from other Federal agencies that
share responsibility in sludge disposal regulation, including
the U.S. Department of Agriculture and the Food and Drug
Administration; officials from municipal wastewater districts;
and researchers from the academic community. The intent of
bringing together this combination of people was:
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1. To provide the EPA Office of Water Program Opera-
tions (OWPO) and EPA Office of Water Regulations
and Standards (OWRS) with a clear understanding of
how the EPA Office of Research and Development
(ORD) can support regulation development.
2. To inform the staff at the EPA's Office of Health
Research/Health Effects Research Laboratory
(OHR/HERL) of the research needs and regulatory
plans of OWPO.
Because the aim of this workshop was to coordinate the
needs and capabilities of offices within the Agency, atten-
dance was limited to EPA personnel and to experts from
outside the EPA who were invited to make presentations.
A list of the names and addresses of the 28 participants and
20 observers is included as Appendix A of this report.
Workshop Agenda
The Cincinnati workshop consisted of two sessions --
1-1/2 days were devoted to the microbiological health
effects issues of municipal wastewater sludge use and
disposal, and 1-1/2 days to the organic chemical health
effects issues. The workshop agenda is provided as Appendix
B of this report. In each session welcoming remarks were
followed by a full day of presentations reviewing the status
of health-effects research and risk assessment and the data
requirements of regulators in those areas. The last half
day of each session was a round-table discussion to plan
how research capabilities could complement current and
projected regulatory needs and to identify the major data
gaps that need to be filled for accurate, cost-effective
risk assessment.
Workshop Report
This report provides a summary of each of the major
presentations listed in the agenda (Appendix B). A list of
the acronyms and abbreviations used within this report is
given in Appendix C. Section II (Microbiology) and Section
III (Organic Chemicals) each contain a summary of the
respective session, the presented papers, and a summary of
discussion items and research needs.
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SECTION II
MICROBIOLOGICAL HEALTH EFFECTS OF
MUNICIPAL WASTEWATER SLUDGE DISPOSAL
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MICROBIOLOGY SESSION SUMMARY
The Microbiology Session covered the following topics:
• The quantity, composition, and variability of the
microbiologcal constituents of municipal wastewater
sludge.
• The behavior and fate of microbiological pathogens
after sludge is applied to land.
• The potential human health risk for:
- infection
- disease
from these pathogens.
• Methods for realistically estimating the potential
risk from pathogens in land-applied sludge, based on:
- modeling
- epidemiologic methods
- direct measurement of indicator organisms.
• The organizational responsibilities, viewpoints,
and approaches of several Federal and municipal
ent it ies.
The first presentation was an overview of the "Quantity,
quality, and mode of current and projected sludge disposal".
Robert K. Bastian of the U.S. Environmental Protection
Agency (EPA) reviewed the wide variety of the physical,
chemical, and biological characteristics of municipal
sludges. Current sewage treatment practices result in nearly
7 million dry tons of raw sludge per year, and, by the year
2000, sludge production is expected to as much as double as
a result of upgrading existing facilities and bringing new
facilities on-line. Based on the current and projected
volumes of sludge production, Bastian indicated that the
major sludge management problems reside with large, urban,
publicly owned treatment works (POTWs).
However, data on the fate of sludge from POTWs is
poor. The major options for disposal currently available to
municipalities are incineration, landfilling, and land
application, but the future of sludge disposal is unclear.
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The remaining presentations of this session were
devoted specifically to microbiological concerns.
Joseph B. Farrell of the EPA reviewed "The establisment
of a regulation for control of pathogens in sludge applied
to land". According to Farrell, years of practical experience
in land application provided regulators with a body of
information for the establishment of three classes of
sludge, based on the microbiological risk to human health if
that sludge were applied to land. The regulators then
specified the nature of the treatment required to place a
sludge in a particular class. These are "processes to
significantly reduce pathogens" (PSRP) and "processes to
further reduce pathogens" (PFRP). Farrell examined alterna-
tive methods for achieving these standards, and suggested
that it may be possible to define the performance of a PSRP
process by simply observing the drop in fecal indicators
from the level in raw sludge solids to those in the sludge
leaving the treatment plant.
Information on the composition of a sludge and the
efficacy of sludge treatment is only a first step in estima-
ting the risk to human health if the treated sludge is
applied to land. This assessment can be approached in
several ways: modeling, epidemiologic studies, and alterna-
tive approaches.
Risk assessment for a local metropolitan area through
modeling was demonstrated by Sydney Munger of the Municipality
of Metropolitan Seattle (Metro). This assessment was
performed for pathogens, organics, and metals. Ms. Munger
reported the risk assessment for pathogens in her talk
"Wastewater sludge microbiological health effects and risk
assessment". She reported the risk assessment for organic
chemicals in the Organics Session (Section III).
Based on the known levels of representative pathogens
in Metro sludge, the efficacy of Metro operating practices,
and literature values for the probability of human exposure
or disease from land-applied sludge, she estimated the risk
from several land-based disposal options: silviculture,
composting, and land reclamation. Ms. Munger concluded
that, with the exception of direct consumption of the
sludge-soil mixture, the risk of human infection or disease
from these practices is low, but she feels that monitoring
programs are necessary to validate the risk assessment
predictions.
Models exist upon which to base the development of
a methodology for conducting risk analyses on a national
basis, but these will be considerably more difficult and
time-consuming than site-specific analyses because of the
difficulty in selecting assumptions to cover nation-wide
variabili ty.
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Bernard P. Sagik from Drexel University looked at risk
assessment from the epidemiologist's point of view. His
paper "Sludge microbiological health effects: the epidemio-
logical approach" used a recent outbreak of avian influenza
as a model for discussing the difficulties in examining
waterborne viral infections in humans. Sagik concludes that
the cost of conducting epidemiological studies in humans and
improving the data base on waterborne viral diseases would
be large. Yet, the risk of groundwater contamination from
the land application of sludge may be real, and the public
may not be wiling to accept that risk, no matter how small.
Thus, research in bacteriology, parasitology, and virology,
rather than epidemiology, may be the most cost-effective
ways of providing the type of data that regulators need. He
also emphasized that the current nutritional health of the
individual and his recent exposure to the same or related
pathogens is very important.
"Alternative approaches to microbiological risk assess-
ment" was the subject of Charles A. Sorber, of the University
of Texas at Austin. Like Sagik, he maintained that epidemio-
logic methods do not appear to be cost effective, and
suggested that well-designed monitoring programs and modeling
hold the most promise for risk assessment. Sorber advocated
the Metro approach, with research focused on improving data
inputs into models. He also suggested that groundwater and
surface water monitoring using "indicator systems" can be
useful in estimating the risk of sludge pathogens to humans.
In "Microbiological risk assessment of sludges: data
required by EPA", Sheila L. Rosenthal of the Office of
Health and Environmental Assessment (OHEA) outlined the type
of data that a regulatory agency needs. She discussed the
risk assessment process that OHEA performs for chemicals.
Such an approach may or may not be suitable for performing a
microbiological risk assessment for land application of
sewage sludge. The type of data required for an assessment
includes information on treatment methodologies and effective-
ness, types of pathogenic organisms, the fate of these
organisms in the environment, types of food crops, groundwater
and surface water contamination, and the relationship
between exposure and disease in humans. She suggested that
a relative risk approach may be useful for determining the
best option for sludge use or disposal.
Charles S. Spooner, Acting Director of the Sludge Task
Force, presented the Task Force's "Organization, responsi-
bilities, viewpoints, and perspectives of pathogen controls".
He outlined the Task Force's Policy on Municipal Sludge
Management, which states the role that EPA, the states, and
local governments should have in sludge management and what
values should guide management decisions. He called for the
examination of practical alternatives to existing regulations,
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and stated the need for increased understanding of current
or future regulations if a national sludge management
program is to be successful.
Rufus Chaney of the U.S. Department of Agriculture
(USDA) then summarized the results and concerns of USDA
scientists after 12 years of intensive sludge research and
evaluation. In his paper, "Assessing potential health
effects of land-applied sewage sludge", Dr. Chaney emphasized
that because the USDA has responsibilities towards soil,
crops, and farm workers, it has been interested in sewage
sludge disposal and regulation and has advised the EPA on
sludge-related issues.
The USDA's approach to land application of municipal
wastewater treatment sludges includes interests in: maintain-
ing the fertilizer value of sludge through appropriate
processes at the treatment works and through sludge injection;
regulation of the application of phytotoxic elements; regula-
tion of the distribution and marketing of composted sludge;
regulation of a broader spectrum of sludge constituents,
such as metals and organics; pretreatment as a mechanisms to
reduce contaminant levels; modification of research protocols
based on 12 years of research experience; and use of monitor-
ing and recordkeeping to increase public acceptance of crops
grown on sludge-treated fields.
Dr. Chaney also presented a PCB risk assessment model
that suggests the food chain may have some protection from
sludge-applied organics, but he emphasized that more research
is needed.
Walter Jakubowski of the EPA Health Effects Research
Laboratory (HERL) then presented a "Summary of the discussion
session on the microbiological health effects of sludge
disposal". The objective of this discussion session was to
coordinate HERL research planning in microbiology with the
regulatory and sludge management needs of other EPA offices.
There was general agreement that epidemiologic approaches
to measuring infection and disease rates are not cost
effective for silviculture and agriculture. However, that
approach may be applicable and desirable for distribution
and marketing (D&M) programs.
The Seattle Metro approach to risk assessment was ex-
amined for use on a national basis. Although data gaps still
exist, risk assessments can be performed now using available
data. Major research needs are in the area of quantitative
methods for pathogens and the effects of environmental
factors on pathogen fate and transport. Walter Jakubowski
then summarized the group's "Recommendations for municipal
wastewater sludge health effects research: microbiology".
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QUANTITY, QUALITY, AND MODE OF CURRENT
AND PROJECTED SLUDGE DISPOSAL
by: Robert K. Bastian
Office of Water, U.S. Environmental
Protection Agency
401 M Street, S.W.
Washington, D.C. 20460
An integral part of almost any wastewater treatment
plant is the sludge management system. Residual solids are
produced in nearly every unit process of conventional
wastewater treatment and a significant proportion of both
capital outlay and operations and maintenance (O&M) costs of
conventional wastewater treatment is associated with sludge
production, processing, and disposal or utilization facilities
and operation.
Over 25 billion gallons of domestic and industrial
wastes are currently discharged daily into the Nation's
municipal sewers by some 150 million Americans and at least
87,000 industrial contributors, the treatment of which
annually produces nearly 7 million dry tons of raw sludge
(resulting in more than 4.2 million tons of processed
sludge) as well as treated wastewater for disposal or reuse.
Nearly 20 percent of this sludge volume is produced by the
publicly owned treatment works (POTWs) located in the
country's 10 largest urban centers. In addition, it is
estimated that nealy 700,000 dry tons of septage are produced
annually from the septic tanks which treat wastes from about
25 percent of U.S. homes. The 1982 Needs Survey (see U.S.
EPA 1983) identified over 15,500 existing POTWs, but more
than 80 percent treat flows less than 1 million gallons per
day (MGD) while fewer than 400 treat flows more than 10 MGD.
Over 7,000 of the POTWs are wastewater treatment ponds that
generally have few or at least infrequent sludge management
problems.
A recent estimate of municipal sludge production rates
based on 1982 Needs Survey data is provided in Table 1. By
the year 2000, the volume of sewage sludge produced is
expected to about double to approximately 14 million dry
tons per year as a direct result of upgrading existing
treatment plants as well as building and operating new
facilities necessary to adequately treat increasing volumes
of municipal wastewater prior to discharge or reuse. For
both periods, about 70 percent of the total amount of sludge
is, or is expected to be, produced by POTWs treating over 10
MGD of wastewater.
Efforts to accurately estimate what is currently being
done with the municipal sludge being produced by the existing
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TABLE 1
ESTIMATED MUNICIPAL SLUDGE
PRODUCTIOK BY POTW SIZE
PCTW SI2E
( *GD)
KO. OF
POTWS
SLUDGE PRODUCED
'ar^ tons/^r)
PERCENT
CP TOT^L
0-2.S
14,168
I, 189,810
17
2.5-5
631
515 ,504
8
5-10
352
5 8 8,445
9
10-20
187
622,478
9
20-5 0
125
924,896
14
50-100
40
6"9 ,091
10
> 100
41
2,324.2^4
34
Totals
15 ,5 4 4
5,843 ,496
Source: Based on data from the 1982 Needs Survey.
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POTWs are greatly hampered by the type of data available and
the lack of data in the 1982 Needs Survey information (Table
2) which does not account for the eventual fate of sludge
from nearly half of the POTWs. However, data generated from
a random survey of 1,011 POTWs conducted for the U.S.
Environmental Protection Agency (EPA or Agency) in 1980,
which accounted for 6.5 percent of the POTWs nation-wide and
about 36 percent of the total municipal sludge generated,
did provide the results presented in Table 3.
Currently the sludge disposal and use alternatives
available to most municipalities for serious consideration
include various versions of incineration (thermal conversion),
landfill, and land application. Various techniques for
processing sludge into products (e.g., soil amendments,
organic fertilizers, dried bulking agents or fuel materials,
aggregate, and even bricks) are available, but most eventually
involve some form or combination of land disposal, land
application, thermal combustion, or other conversion of the
end products. Ocean disposal of sewage sludge (both ocean
dumping from vessels and ocean outfall discharges) has been
phased out by many municipalities over recent years, in part
due to the requirements of the secondary treatment provisions
of the Clean Water Act (CWA) and the ocean dumping require-
ments under the Marine Protection, Research, and Sanctuaries
Act (MPRSA) and their amendments. However, there has been
increasing interest in and pressure exerted to cause the
U.S. Environmental Protection Agency to reconsider the
potential for continuing many of the existing ocean disposal
projects as well as allowing the establishment of new
projec ts.
What will the municipalities do with their sludge in
future years? With the current uncertainty as to the future
of ocean disposal, serious concerns and increasing constraints
facing land application [including distribution and marketing
(D&M) programs], landfill and lagooning practices, strict
air emission standards, increasing capital costs, and O&M
concerns, as well as escalating fuel costs facing thermal
conversion alternatives, some individuals question whether
there will be any viable yet cost-effective sludge management
alternatives available in the future.
The characteristics of and constituents present in
municipal sewage sludges can vary widely from plant-to-plant,
depending upon their origins and the treatment processes
used to alter the characteristics and make-up of the sludge
itself, making it difficult to make generalized statements
about their physical, chemical, and biological properties.
In reality almost anything can be found in sludge. Some of
the physical, chemical, and biological characteristics and
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TABLE 2
MAJOR MUNICIPAL SLUDGE
DISPOSAL/UTILIZATION PRACTICES
PRACTICE
NO. OF
POTWS
ESTIMATED
SLUDGE PRODUCED
(dry tons/yr)
PERCENT OF
TOTAL
SLUDGE
PERCENT OF
TOTAL
FACILITIES
Landf il1
5 ,613
2,219,430
32
36
Inc i nera tion
30 6
1,207,734
18
2
Land Application
1,722
873 , 151
13
11
Ocean Disposal
41
483 ,488
7
1
Other
183
305 ,330
4
1
Missing Data
7 , 679
1,754,360
26
49
Total
15 ,544
6,843,493
Source: Based on data from the 1982 Needs Survey.
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TARLE 3
DISTRIBUTION OF SLUDGE DISPOSAL/UTILIZATION PRACTICES
FOR 1,011 SURVEYED POTWS (BY PERCENT OF SLUDGE VOLUME)
PRACTICE
SMALL POTWS
(<1 MGD)
MEDIUM POTWS
( > 1: < 10 MGD)
LARGE POTWS
(>10 MGD)
TOTAL
Landfill 31
Incineration 1
Land Application 39
Distribution and 11
Marketing
Ocean Disposal 1
Other 17
35
1
39
18
12
12
32
21
19
4
12
15
27
24
18
4
12
Source: EPA Office of Solid Waste.
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constituents of municipal sludge that are of potential
importance or concern regarding sludge management are listed
in Table 4. Ranges and typical values for a number of these
properties are shown in Table 5 for several sludge types,
and provide a general perspective on the composition of
sewage sludges. Note especially the wide ranges shown for
most chemical constituents.
REFERENCES
Farrel, J.B. 1974. Overview of sludge handling and disposal
In: Municipal sludge management. Proceedings of the
National Conference on Municipal Sludge Management, June
11-13, Pittsburgh, Pennsylvania. Information Transfer,
Inc., Rockville, Maryland. pp. 5-10.
Farrel, J.B., and B.U. Salotto. 1973. The effects of
incineration on metals, pesticides, and chlorinated
biphenyls in sewage sludge. Proceedings, National
Symposium on Ultimate Disposal of Wastewaters and Their
Residuals, Durham, North Carolina, April 26, 1973.
Water Resources Research Institute, North Carolina
State University, Raleigh, North Carolina. pp. 186-198.
Furr, A.K., A.W. Lawrence, S.S.C. Tong, M.C. Guandolfo, R.A.
Hofsader, C.A. Bache, W.H. Gutenmann, and D.J. Lisk.
1976. Multielemental and chlorinated hydrocarbon
analysis of municipal sewage sludges of American
cities. Environmental Science and Technology 10(7):
683-687.
Metcalf and Eddy, Inc. 1972. Wastewater engineering.
McGraw-Hill, New York, New York.
Palfi, A. 1973. Survival of enteroviruses during anaerobic
sludge digestion, ^n: S.H. Jenkins (ed.), Advances in
water pollution research. Proceedings of the Sixth
International Conference, Jerusalem, June 18-23, 1972.
Pergamon Press, New York. pp. 99-104.
U.S. EPA. 1983. The 1982 Needs Survey: Conveyance, treat-
ment, and control of municipal wastewater, combined
sewer overflows, and stormwater runoff -- summaries of
technical data. EPA 4 30/9-83-00 2. U.S. Environmental
Protection Agency, Office of Water Program Operations.
June 15, 1983. 192 pp.
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TABLE 4
SLUDGE CHARACTERISTICS AND CONSTITUENTS
OF IMPORTANCE OR POTENTIAL CONCERN
Physical Characteristics
Volume
Density
Particle size
Total Solids
Biological Constituents
Bacteria
Salmonella spp.
Escherichia coli
Pseudomonas spp.
Virus
Enteroviruses
Polioviruses
Coxsackie viruses
Echoviruses
Hepatitis viruses
Adenoviruses
Reovi ruses
Chemical Constituents
Dissolved solids
Volatile solids
Heat value (heat of combustion)
Fungi
Aspergillus spp.
Parasites & Protozoa
E. histolytica
Ascans spp.
Toxacara spp.
Trichluris spp.
Hymenolepis spp.
Organic Carbon
Total Nitrogen
Ammo n i a-N i t roge n
Ni trate-N1trogen
Total Phosphorus
Total Potassium
Total Sulfur
Sodium
Calcium
Aluminum
Arsenic
Be ry 11 i um
Boron
Cadmium
Chromium
Copper
Cyanide
Flourine
Gold
Iron
Lead
Magnes ium
Manganese
Mercury
Molybdenum
Nickel
Palladium
Platinum
Selenium
Silver
Tin
Vanadium
Zinc
DDT
DDD
DDE
Dieldrin
Aldrin
Chlordane
Heptachlor
Lindane
Toxophene
Endrin
Bis( 2-ethylhexyl)phthai ate
Di-n-butyl phthalate
Chloroethane (ethyl chloride)
Methyl chloride
Methyl bromide
Vinyl chloride
1.1-dichloroethylene
1.2-dichloropropane
1.3-dichloropropane
Pentachloroethane
Hexachloroethane
Carbon tetrachloride
Dichlorodifluoromethane
Dichlorobromomethane
Trichlorofluoromethane
Tetrachloroethylene
Trichloroethylene
Hexachlorobutadiene
Chloroform
Bromoform
1,1,2,2-tetrachloroethane
1.1.1-trichloroethane
1.1.2-trichloroethane
Benzene
Chlorobenzene
1,4-dichlorobenzene
1.2-dichlorobenzene
1.3-d i chlorobenzene
1.2.4-dichlorobenzene
1,2,3-trichlorobenzene
1.3.5-trichlorobenzene
Hexachlorobenzene
Benz idine
Phenol
Pentachlorophenol
2.4-dichlorophenol
4-chloro-m-cresol
(4-chloro-3-methylphenol)
Toluene
Naphthalene
2-chloronapthalene
Acenaphthylene
Anthracene
Benzo(a)anthracene
(1,2-benzanthracene)
Ideno (1,2,3-cd) pyrene
Benzo(a)fluoranthene
PCBs
(Polychlorinated biphenyls)
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TABLE 5
PROPERTIES OF VARIOUS SLUDGES*
RAW PRIMARY
SLUDGE
RAW ACTI-
VATED SLUDGE
TRICKLING
FILTER HUMUS
DIGESTED
SLUDGE
RANGE
MEDIAN
RANGE MEDIAN
RANGE MEDIAN
RANGE
MEDIAN
REFERENCE
Total solids (TS) (%)
3-7
5
1-2 1
2-7 4
6-12
10
(1)
Volatile solids (% TS)
60-80
70
60-80
50-80
30-60
40
(1)
Thermal content
(kj/kg) x 104
1.6-2.3
0.72-1.6
(1)
Nutrients (% dry wt)
Nitrogen
Phorphorus
Potass ium
1.5-8
0.8-2.7
0-1
3
1.6
0.4
4.8-6 5.6
3.1-7.4 5.7
0.3-0.6
1.5-5 3
1.4-4 3
0-1
1.6-6
0.9-6. 1
0.1-0.7
3.7
1.7
(1)
(1)
(1)
PH
5-8
6
6.5-7.5
7
(1)
Alkalinity
(ppm CaCOj)
500-1,500
600
2,500-3,500
3,000
(1)
Metals (ppm dry wt)
Arsenic
Cadmium
Chromium
Copper
Lead
Mercury
N icke 1
Sele n i um
Z inc
385-1,500 916
950-3,650 2,500
3-30
5-2,000
50-30,000
250-17,000
136-7,600
3.4-18
25-8,000
1.7-8.7
500-50,000
14
15
1,000
1,000
1,500
6.9
200
2 ,000
(2)
(3)
(3)
(3)
(2)
(2)
(2)
(2)
(2)
Persistent Organics
(ppm dry wt)
PCBs
Chlordane
Dieldr in
1. 2-10 5
3-30
0.3-2.2
3.2
0. 16
(3)
(3)
(3)
*
Raw primary sludge results from sedimentation of wastewater solids, activated sludge from biomass of sus-
pended microorganisms, and trickling filter humus from biomass of attached microorganisms. Stabilization of
organic matter in these sludges by aerobic or anaerobic biological processes produces digested sludge. Levels of
metals, persistent organics, and pathogens affect the reuse of sludges. Digestion reduces virus and bacteria
from levels found in raw sludges, but does not affect metals or persistent organics. Nutrient content of
digested sludge can be used by crops. Thermal content determines how easily sludge can be oxidized after
sufficient dewatering.
-------
TABLE 5 (CONT.)
RAW PRIMARY
SLUDGE
RAW ACTI-
VATED SLUDGE
TRICKLING
FILTER HUMUS
DIGESTED
SLUDGE
REFERENCE
RANGE
MEDIAN
RANGE MEDIAN
RANGE MEDIAN
RANGE
MEDIAN
Pathogens
Virus (PFU/100 ml)
7.9
0.85
(4)
Coliform ( 106/100 ml) 11.0-11.4
2-2.8
11.5
0.4
(5)
Salmonella (per 100 ml)
460
74-23,000
93
29
(5)
Pseudomonas (per 100 ml)
46,000
1,100-
11,000
34
(5)
24,000
(1) Metalf and Eddy, Inc. (1972).
(2) Furr et al. (1976).
(3) Farrell and Salotto (1973).
(4) Palfi (1973).
(5) Farrell (1974).
Adapted from: National Academy of Sciences. 1977. Analytical studies for the U.S. EPA. Volume IX.
Multimedia management of municipal sludge. 202 pp.
K>
I
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THE ESTABLISHMENT OF A REGULATION FOR CONTROL
OF PATHOGENS IN SLUDGE APPLIED TO LAND
by: Joseph B. Farrell
MERL, WRD
U.S. Environmental Protection Agency
26 West St. Clair Street
Cincinnati, Ohio 45268
THE INITIAL BACKGROUND
In preparing to regulate pathogen exposure from sludge
use on land, regulators were fortunate to find that much
practical information on the practice was available. Use of
nightsoil to fertilize crops had been going on since the
beginning of civilization. Agricultural use of sludge from
wastewater treatment is as old as wastewater treatment.
Consequently, a substantial body of experience already
existed. This common practice revealed some helpful
facts:
(1) Use of nightsoil directly on crops was a dangerous
pract ice.
(2) Use of wastewater containing sewage solids was a
dangerous practice.
(3) Use of sewage sludge from anaerobic digesters on
farmers' fields appeared to cause no traceable
clusters of illness.
(4) Use of raw sludge on soil contaminated drinking
water supplies (in at least one case that I know
of) and caused illnesses.
(5) Heat dried sludge was marketed all over the United
States and appeared to cause no traceable clusters
of illness.
(6) Sludges contained all the solids originally in the
wastewater. Thus pathogenic agents (including
viruses which adsorb to solids) were largely in
the solids. The conventional treatment processes
reduced the densities of these agents but did not
eliminate them.
The body of available- information also revealed that
sludge was used (a) to upgrade parkland and renovate damaged
land so that some kind of vegetation would grow, (b) to
fertilize farmers' fields and orchards, and (c) to fertilize
home vegetable gardens.
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REGULATORY CLASSES ACCORDING TO RISK
It is immediately apparent that the riskiest of the
uses of sludge is use on home vegetable gardens. Use on
farmers' fields and orchards seems less risky because access
is limited and, because single crops can be grown on large
acreage, exposure to sludge could be restricted to low
hazard crops like corn. Use on land growing vegetation in
parks or in the wild could be hazardous or nonhazardous
depending on the degree of public use.
The regulators chose to establish three regulatory
classes (CFR ^0_, Part 257), which seemed to protect against
all contingencies:
(1) Raw sludge could not be used on the land surface.
(2) Raw sludge that had gone through a reliable
stabilization treatment process at the sewage
treatment plant could be used on crops provided
access was restricted and crops for direct human
use that contacted the ground were not grown.
(3) With respect to pathogens, properly disinfected
sludge could be used anywhere.
Sludge used on home vegetable gardens required class
(3) treatment, that is, disinfection. Most used by farmers
or for renovation required class (2) treatment. Use on
parkland required class (3) treatment, unless access was
restricted and then class (2) would apply.
The regulators were obliged to specify the nature of
the treatment required for class (2) and class (3) treatment.
They defined class (2) treatment by indicating that the
sludge needed to be treated by a "process to significantly
reduce pathogens" (PSRP) and class (3) treatment is treatment
by a "process to further reduce pathogens" (PFRP)(CFR 40,
Appendix II).
BASIS FOR DEFINING PSRP AND PFRP
The regulatory framework has one more requirement.
PSRP and PFRP need definition. One approach to defining
these terms is to decide that these processes should reduce
pathogen densities to certain levels. For example, for
PSRP, pathogens should be below some reasonable levels and
for PFRP, it could be decided that all pathogens would be
below detection limits. A second approach is to require the
process to reduce pathogen densities by a certain extent.
2-15
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The first approach had decided drawbacks for PSRP. Our
experience shows two circumstances that make it impossible
to establish certain exiting density levels of pathogens as
performance requirements for PSRP. The first circumstance
is that wild fluctuations occur in the densities of pathogens
(viruses, bacteria, helminths, protozoa) in raw sewage
sludge. For example, the density (number of organisms/gram)
of Salmonella sp. can change by a factor of several thousand
from one week to the next. The second circumstance is the
nature of stabilization processes such as anaerobic digestion.
Anaerobic digestion at 35°C can reduce pathogenic bacteria
and viruses by one log relatively easily (Pedersen 1981),
but we are not at all sure how to substantially increase
this reduction. It may require doubling or tripling the
residence time to get two or three logs reduction, but we
are not certain of this. Besides, there is no operating
means to vary residence time from day to day, and there is
no way to have the excess capacity in the plant to, for
example, triple the residence time. It is only possible to
run these processes at fixed conditions and accept the
number of logs of reduction they produce. The only alterna-
tives are to scrap all existing stabilization technology and
search for new methods that produce constant downstream
pathogen densities, or accept the fact that a process
performance standard (e.g., require that a process reduce
viruses and pathogenic bacteria one log) is the only way to
define PSRP. The regulators chose the latter course.
Note that the PSRPs reduce pathogenic bacteria and
virus densities (protozoa are also fragile in PSRPs) but
they do little damage to helminth eggs. The other restric-
tions that accompany PSRPs (restricted access, time require-
ments before certain crops can be planted) were designed to
minimize risk from these pathogens.
With PFRPs, it is possible to either choose a process
performance standard or a pathogen density standard. The
FRP processes have great capacity for producing multilog
changes in pathogen density. They use either thermal
processes or ionizing radiation. With thermal processes,
density reductions are first order with respect to time
(delta log density/delta time is constant) so the increase
in process performance with time is predictable. Also,
performance is very sensitive to minor changes in tempera-
ture. Thermal processes can be designed to give as many log
reductions as can conceivably be needed to get pathogens to
safe levels or below detectable levels. Radiation processes
are also first order with respect to time. Once source size
is selected, dose is related inversely to throughput and
only to throughput. Thus they are not as flexible as
thermal processes. Still, they can produce multilog reductions
2-16
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in pathogens. It is possible to operate them to meet output
pathogen density criteria (by varying throughput rate) when
upstream densities vary, but it is simpler to design them
conservatively and operate them at fixed conditions. Since
radiation processes usually operate on the sludge output of
PSRPs, pathogen densities fluctuate much less wildly than in
raw sludge, so a conservative design is not prohibitive in
cost.
TANDEM PROCESSES
The regulation as written provides for alternative
processes for reducing pathogen densities that must be shown
to be the equivalent to standard PSRPs. The regulation
should remind users that two processes such as aerobic
digestion and sand bed drying can be combined "in tandem".
Thus when one process is inadequate, such as aerobic
digestion in the winter (e.g., 0.5 log reduction), sand-bed
drying (e.g., 0.6 log reduction) could be put together with
it to qualify as a PSRP.
PROCESSES WITHOUT A PRIMARY SLUDGE
PSRP requires that the final product of the stabilization
process be one log lower in pathogens than the mixture of
waste-activited sludge (WAS) and raw sludge drawn from the
primary clarifier. Many small secondary treatment plants
have no primary clarifier — all the sludge then is waste
biological sludge. This sludge may be lower in pathogens
than the mixture of WAS and primary sludge solids in a
conventional plant. Thus the requirement that sludge must
be reduced in pathogens by one log is perhaps unfair.
Research currently underway on density levels of these
sludges indicates that they may be slightly lower in pathogen
densities than a mixed sludge from a conventional plant.
More information is needed to establish the magnitude of
this effect.
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USE OF FECAL INDICATOR DENSITIES TO SHOW
THAT A SLUDGE HAS EXPERIENCED A PRSP
In our current investigations of pathogen and indicator
organism densities at a number of small treatment plants,
we have observed that, although densities of pathogenic
bacteria fluctuate wildly, the fecal indicators have been
nearly the same at a number of different plants. This
observation could point to a simpler definition of PSRP.
We have already come to the conclusion (not discussed
yet in this presentation) that it is possible to define the
performance of a potential PSRP by observing the drop in the
fecal indicators. If they average two log reductions, we
accept them as PSRPs. This conclusion is based on observa-
tions of the relative drop in the fecal indicators versus
viruses and Salmonella sp. in anaerobic digestion and sludge
storage investigations. Now we have obtained data that lead
us to believe that the fecal indicators in the entering
sludge solids are virtually constant. Thus, there is a good
likelihood that if a sludge is two logs lower in fecal
indicator densities than the usual level found in raw
sludge solids, the sludge has received pathogen reductions
equivalent to that achieved by a PSRP.
This simplification means that if there is a question
about the pathogen-reducing efficacy of a process train or
even if the quality of a sludge leaving a treatment plant is
questioned, all we need to do is run the fecal indicators on
it. We do not need to collect a lot of simultaneous in-and-
out data on the PSRP or series of processes that make up the
PSRP.
More data are needed to establish the fact that all raw
sludges entering digesters have about the same fecal indicator
counts. This work will start this fiscal year.
REFERENCES
Code of Federal Regulations £0_, Part 257 . Criteria for
classification of solid waste disposal facilities and
practices. Par. 257.3-6, Disease.
Code of Federal Regulations 40^, Appendix II. A., Processes
to Significantly Reduce Pathogens. B., Processes to
Further Reduce Pathogens.
Pedersen, D. 1981. Density levels of pathogenic organisms
in municipal wastewater sludge -- a literature review.
EPA Report No. 6 00/2-81-17 0. NTIS PB82102286 (Oct.
19 81) .
2-18
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WASTEWATER SLUDGE MICROBIOLOGICAL HEALTH EFFECTS
AND RISK ASSESSMENT
by: Sydney Munger
Senior Microbiologist
Water Resources Section
Water Quality Division
Municipality of Metroplitan
Seattle (Metro)
Exchange Building
621 Second Avenue
Seattle, Washington 98104
INTRODUCTION
Definition of Risk
Risk is defined in this presentation as a measurement
of the probability of harm occurring to human health as a
resut of pathogens in land-applied sludge. A risk assess-
ment should not attempt to make a judgment as to the absolute
safety of a given action but rather analyze data available
for the determination of risk. As discussed by Lowrance
(1976) in his book Of Acceptable Risk, nothing we do or have
imposed on us is absolutely free of risk. The concept of
safety should be viewed as a judgment concerning the accept-
ability of the risk involved. The scientific process can
measure the risks involved. The judgment as to the accept-
ability of these risks is a socio-political process in which
the scientist has no special role.
Purpose of Risk Assessment for Municipalities
Environmental health risk assessment is most commonly
applied to the derivation of specific pollutant criteria by
national regulatory agencies. The same process can also be
adapted for use by local municipalities to assess the risk
of sludge reuse. The products of a health risk assessment
on sludge land application can be used by municipalities
to:
(1) Define the risks based on local sludge constitutents
and the local sludge management program.
(2) Define gaps in the data base which would allow a
more precise estimate of risks.
(3) Define priorities for a sludge land application
demonstration site monitoring program.
2-19
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(4) Define levels of risks to citizens who can then
decide the level of acceptable risk and advise the
local policy makers.
(5) Define level of risks to local policy makers for
management decisions.
DETERMINATION OF RISK
Risk determination as described by Rowe (1977) in An
Anatomy of Risk includes five definition steps: causative
events, outcomes, exposure, consequences, and consequence
values. For the purpose of this risk estimation, the
causative events include the conditions of application and
levels of risk-causing factors present in the sludge. The
outcome of these applications is the presence of varying
levels of pathogens in the environment. To understand the
probability of exposure and resulting consequences, the
pathways of pathogen transport and mechanisms of their
transmission to humans must be defined. The value of, or
decision to accept, the resulting consequence can then be
discussed by concerned citizens and local policy makers.
Risk estimation for the reuse of sludge in silviculture,
compost, and land reclamation projects will be calculated in
this paper based on the known levels of representative
pathogens in Metro dewatered sludge and Metro operating
practices.
Causative Event
Sludge management options contained in Metro's Sludge
Management Plan (Metro 1983a) includes emphasis on silvi-
culture with land reclamation and composting. Management
guidelines are defined by the Washington State Department of
Ecology (WDOE 1982), and operating practices for Metro are
presented in the Sludge Management Plan (Metro 1983a).
The risk estimation was based on the numbers of
Salmonella, Enterovirus, Ascaris, and Giardia in digested,
dewatered sludge. Salmonella was chosen to be representative
of the bacterial pathogens because most serotypes of Salmonella,
in high enough numbers, are capable of causing human disease
thus providing a worst case situation. A total Enterovirus
count was used because enumeration of specific types of
virus was not practicable and in some cases not possible.
Again, it provides a worst case analysis.
Both Ascaris and Giardia were considered because of
the relative hardiness of the Ascaris ova and the several
2-20
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instances of waterborne giardiasis having occurred recently
in Washington state.
The compost risk assessment assumes a well controlled
and monitored process leading to a product in which pathogens,
with the exception of thermophilic fungi, are below the
limits of detection. Aspergillus fumiqatus will be con-
sidered representative of the opportunistic fungi which
proliferate in the composting process.
Outcomes
The application of sludge to land can potentially
result in the transfer of pathogens from the sludge to air,
soil, and surface or groundwater. Using data developed
during an intensive monitoring program of Metro sludge in
the summer of 1981, and an extensive literature review (Metro
1983b), the estimates for environmental concentrations have
been projected (Metro 1983c).
Exposure
To help understand the probability of exposure to
pathogens in the environment, the pathways for microbial
transport are diagrammed in Figure 1.
The outlined boxes can serve as routes of transmission
from the environment to humans by the following mechanisms:
(1) Aerosols —> inhalation —> alveolar deposition or
inges tion.
(2) Surface water —> accidental or planned ingestion
and physical contact.
(3) Groundwater —> planned ingestion.
(4) Animals (vectors) —> contaminated food —> inges-
tion; physical contacts —> abrasions; hand to mouth,
i.e., petting dog or cat.
(5) Trees, undergrowth, soil, litter layer —> physical
contact; ingestion of soil by children; ingestion
of mushrooms not thoroughly washed.
2-21
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Digested Sludge
Application (Spray) ~
Aerosols
Figure 1. Pathways of Microbial Transport from Sludge in Silviculture Application.
2-22
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Consequences
The consequence of exposure to one or more routes of
transmission is dependent on the minimal infectious dose for
a given organism. The minimal dose which will cause infec-
tion (MID) for each of the organisms considered in this
analysis is given in Table 1.
It is important to distinguish between infection and
disease for many enteric organisms. Infection occurs when
the pathogen multiplies in the host, which may result in
fecal shedding and/or specific antibody elevation, while
disease is a result of infection culminating in clinical
symptoms. The pertinent point is that infection often
occurs with no clinical signs of illness. The MID value
given in Table 1 can cause infection, but this infectious
state may not result in illness. Thus the consequence of
exposure to land-applied sludge, via any of the routes of
transmission described resulting in the ingestion of the MID
of any pathogen, is possible infection but not necessarily
disease.
TABLE 1
MINIMUM INFECTIOUS DOSE FOR EACH
ORGANISM CONSIDERED IN THIS ANALYSIS
ORGANISM MINIMAL INFECTIOUS DOSE
Salmonella 10 0
Enterovirus 4 TCID50*
Ascaris 1 egg
Giardia 10 to 25 cysts
*TCID5q = tissue culture infective dose (in 50
percent of cultures inoculated).
The probability that the infection or disease conse-
quence will actually occur can best be estimated by the
quantity of air, soil, and water from each environmental
compartment that must be ingested within a short period of
time to supply the minimal infectious dose. The quantities
are presented in the Metro Risk Assessment (Metro 1983c) and
are based on the MID and concentrations for each parameter in
a specific environmental compartment. It is shown that the
risk of salmonellosis via the water route is very low if one
agrees that the ingestion of 0.88 to greater than 8.8
gallons of stream water at one given time is remote. This
risk will become even less as the Salmonella die-off over
time. During the initial three-month period following
sludge application, the child with a tendency to consume
2-23
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dirt (pica) may be at risk prior to die-off of the Salmonella.
It is unlikely, but possible, that such a child could consume
0.07 pound of sludge-soil resulting in a case of salmonellosis.
The potential for viral infection is again very low,
especially via the water route. The opportunity for infection
is remote unless 400 gallons of surface water is consumed at
one given time shortly after sludge is applied. Again in
the case of the child with pica, the risk of infection is
higher during the first three months prior to the die-off of
the virus. It is conceivable that consumption of 0.1 pound
of sludge-soil could result in an Enterovirus infection. As
part of Metro's management plans for any sludge application
project, public access is controlled, making it difficult
for even the most persistent child to consume any measurable
quantity of sludge-soil.
The risk from parasites in Metro sludge is very low
due to very low initial concentrations in the dewatered
sludge.
The probability that infection or disease will occur
from the production or use of compost is limited to that
caused by A. fumigatus. The risk of exposure to aerosolized
spores would be limited to compost operators and potentially
the neighbors living within one kilometer of the site. Of
those exposed, only those predisposed by certain lung
diseases and immunosuppressant drugs are likely to become
infected. Other individuals may be hypersensitive to
Asperg illus spores and when exposed can develop allergic
bronchopulmonary aspergillosis, a type of asthma. This risk
is not unique to sludge compost but rather any compost
operation using cellulosic material.
CONCLUSIONS
It is possible to predict the risks of infection on
or near a sludge land application site utilizing available
.published research. With the exception of direct consump-
tion of the sludge-soil mixture that risk estimation is very
low for silviculture, land reclamation, and composting.
As a municipality facing continuous production of 200
tons per day of dewatered sludge, we feel that sufficient
research is available to justify proceeding with an opera-
tional program. We do remain committed, however, to
assuring the people of our region that what we do is
environmentally sound — that's what the organization was
built on and remains loyal to. It is with this in mind
2-24
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that we are proposing comprehensive monitoring programs on
operational demonstration sites to validate our risk assess-
ment predictions. Such a monitoring program would measure
the environmental fate of representative compounds and
organisms for each transport pathway. It is the position
of Metro that demonstration projects of this type should
receive high priority when federal funding decisions are
made.
REFERENCES
Lowrance, W.H. 1976. Of acceptable risk. William Kaufman,
Inc., Los Altos, California.
Metro. 1983a. Sludge management plan. Metro Report.
Municipality of Metropolitan Seattle, Washington.
Metro. 1983b. Metro sludge quality: monitoring report
and literature review. Metro Report. Municipality of
Metropolitan Seattle, Washington.
Metro. 1983c. Health effects of sludge land application:
a risk assessment. Metro Report. Municipality of
Metropolitan Seattle, Washington.
Rowe, W.D. 1977. An anatomy of risk. John Wiley and Sons,
New York, New York.
WDOE. 1982. Best management practices for use of municipal
sewage sludge. Washington State Department of Ecology,
Olympia, Washington.
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SLUDGE MICROBIOLOGICAL HEALTH EFFECTS:
THE EPIDEMIOLOGICAL APPROACH
by: Bernard P. Sagik
Drexel University, 1-203
32nd and Chestnut
Philadelphia, Pennsylvania 19104
In organizing my thinking on this topic my attention
focused on three groups of questions:
(1) What is an epidemic; an epizootic?
(2) Is the issue of sludge disposal in the U.S. one of
epidemics and epizootics, or is it one of aesthetic
and social judgement of acceptability; if the
latter, should it be evaluated by conventional
epidemiological approaches?
(3) Are there alternatives to the statistical, retro-
spective approach inherent in epidemiology, such
as rapid detection techniques and the modeling
of epizootics, which would enable us to make a
reasonable assessment of the microbial risks
associated with municipal sludges? (These possi-
bilities are posed on the not unreasonable
assumption that prospective planned epidemics are
not likely to get favorable environmental impact
review.)
I specifically have chosen to ignore the ample literature on
viral and bacterial causality in waterborne epidemics. You
have all seen those reviews before.
An epidemic, defined in layman's terms (Random House
Dictionary 1978), is: (1) an adjective meaning affecting at
the same time a large number of persons in a locality and
spreading from person to person as a contagious disease not
permanently prevalent there; (2) a noun meaning a rapid
spread or increase in the prevalence of something. An
epizootic is a descriptor (adjective) of diseases preva-
lent temporarily among animals. Thus, newspaper readers
in the Northeast in October, November, and December of 1983
learned that avian influenza was temporarily prevalent among
poultry (chickens, primarily, and turkeys) in the Lancaster
area of Pennsylvania initially and then had spread beyond
the federally-established quarantine area into New Jersey,
Delaware, and probably Maryland. The toll from this rela-
tively mild outbreak (it was focused in a 3,100-square-mile
area) was well over 6,000,000 birds; some 125 flocks had
2-26
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to be destroyed to contain the epizootic. Other measures
used, in addition to outright destruction of whole flocks,
included: protective clothing, head gear, and gloves for
workers and visitors that was removed before leaving
one farm and entering another; disinfecting shoes and farm
vehicles; spraying farms with insecticides to kill flies
which can carry the virus adventitiously.
Avian influenza is not a human pathogen, hence the
term epizootic rather and epidemic is used to describe the
incident. But the outbreak is of interest because it
"provides us with pieces of basic information that could
lead to an understanding of how ribonucleic acid (RNA) can
change the nature of a virus to produce such a virulent
disease" (R.G. Webster, quoted in the Philadelphia Inquirer
11 December 1983 IG, 4G). Webster thought the outbreak
important in that it could serve as a model of how an entire
human population could be afflicted, as in the 1918 swine
influenza catastrophe which took thousands of lives.
Of particular interest is the probable mode of spread:
although not infected by the virus, humans were carrying it
passively on their bodies, clothes, shoes, and work tools.
Avian influenza virus can replicate in migratory water fowl
without harmful effects. Webster theorized that the virus
was picked up by an area poultry flock through wild duck
excrement that contaminated chicken feed. Initially, in
April 1983, the effects of the disease were mild. In
mid-October the virus mutated into its present deadly
form. This incident is reported in detail so that one can
see the approach inherent in the epidemiologic approach: it
is essentially a retrospective analysis and one needs large
numbers to make that analysis convincing.
The distinguished virologist and epidemiologist
Joseph L. Melnick asked "Are conventional methods of
epidemiology appropriate for risk assessment of virus
contamination of water?" (Melnick 1977). He concluded that
there was no easy answer. The human enteric viruses which
can be present in water are numerous and the potential
routes of transmission back to man are many.
If, as Melnick argued, viruses occur plentifully
in water, why can't we readily measure the risk of disease
in the exposed populations? In short, why isn't the human
population as amenable to study as the avian population
described earlier? "Where", to quote Melnick:
a virus infection has a short and uniform incubation
period and produces a characteristic easily recognizable
disease, carriage of the virus by water routes can be
2-27
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traced with a fair degree of accuracy. In contrast . .
the characteristics of many viral diseases are such
that their transmission by water is very difficult to
recognize . . . [such] viruses include those . . .
which produce clinically observable illness in only a
small fraction of the persons who become infected,
those . . . which produce diseases with widely variable
incubation periods, and those viruses which are easily
spread by direct human contact [my emphasis].
As Melnick noted, the:
. . . standard criteria of a waterborne illness are
(1) a high attack rate among those who recently drank
the water and a low attack rate among those who were
not so exposed, and (2) no person-to-person nor other
common route of transmission among the cases.
Because much of the U.S. population has prior immunity
(due to vaccination or infection), most persons exposed would
not truly be at risk or would suffer at most inapparent and
transient infection. (Contrast this with the avian influenza
outbreak.) Further, it is known that the ratio of inapparent
infection to overt disease is quite high with enteroviruses.
Thus, even among truly susceptible persons, clinical illness
would be uncommon. Finally, the clinical responses among
those who did become ill would likely be so varied as to
make it improbable that we would recognize them as being due
to a single etiologic agent. The exception to all this
is (paraphrased from Goldfield 1976) hepatitis A.
Melnick has pointed out that climate is an important
factor in the prevalence of enteroviruses in the stools of
healthy children, the pre-school populations of southern
cities of the U.S. having a higher incidence of cytopathic
enteroviruses than those of northern cities; the lower
socioeconomic districts having three to six times the
incidence of higher groups. Given that these viruses spread
readily from child-to-child and within families, how is one
to assign a specific risk to contaminated water supplies?
Even granting, as Melnick did, that:
water containing low levels of virus might spread
infectious seed [and that] . . . these sporadic
seedings would then act as foci for person-to-
person contact in the community, . . . the effect
would not be noticeable because of the high ratio of
inapparent to clinical cases.
This led him to conclude that "... funds should be spent
on projects aimed at reducing or eliminating viruses from
. . . sources of drinking water itself" (Melnick 1976).
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The costs of making that statement a reality, "...
reducing or eliminating viruses from our sources of drinking
water as well as from drinking water itself . . . ", are
staggering to contemplate and unlikely to be provided on the
basis of the data presently available.
In his paper "A critique of microbiology research
needs", Sumner M. Morrison (1983) noted that the basic
purpose of sewage treatment hasn't changed in the last
hundred years; our acceptance or tolerance of residues
containing large populations of potentially disease-producing
organisms has diminished. However, this intolerance,
Morrison implied, may be more social or aesthetic than
health-related. Nevertheless, he expressed concern for the
better understanding of the emergence of new bacterial
agents of disease and of opportunistic organisms in order to
determine health risks.
At the same workshop, D.O. Cliver (1983) presented
"A critique of virology research needs" and concluded that
there was " . . . no aspect of on-site or soil treatment of
wastewater of which the virologic features are not in need
of further study . . . the growing trend to use soil in
treating urban wastewater presents similar risks; . . . the
potential for groundwater contamination ..." is present
and real in Cliver's view, nor are viruses the only contam-
inants of concern to him. In this, he echoes Dudley et al.
(1980), who reported a scheme to determine the types and
numbers of pathogenic and potentially pathogenic bacteria in
sludges as prelude to ascertaining the health risks that may
be posed by the land application of sewage sludges.
In the draft copy of the Proceedings of the 1983 Denver
Workshop on Utilization of Municipal Wastewater and Sludge
on Land (Page et al. 1983), the editors summarized Workshop
Highlights, including the following statements under "Research
needs and recommendations":
Major research needs include: risk assessment data
for pathogens and organic contaminants in wastewater
and sludges; land treatment system case studies and
follow-up studies . . . [however] epidemiological
studies no longer remain a high priority research
need.
For bacteriology, information needs include: survival
and growth of pathogens, improvement of detection
methodology and virulence assessment, effectiveness and
mechanisms of treatment processes, relevance of current
indicators and their movement through soils.
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For parasitology, the needs include: pathological
effects of repeated low-level ascarid infections;
virulence of swine v_s human Ascaris; potential patho-
logical significance of Naegleria and similar organisms
in waste-treated soils; and survival of Ascaris ova in
sludge-treated soils.
For virology, the needs include: site monitoring
of survival and movement of viruses under a wide range
of soils, climatic, hydrologic, and waste conditions;
effectiveness of conventional sewage treatment processes
alone and with land treatment; and methodology to
detect hepatitis A, Norwalk agent and rotaviruses.
Details for each of these subject areas can be found in
Norman E. Kowal's encylcopedic "Overview of public health
effects" in that same draft Proceedings. And a very good
summary of a panel discussion on "Public health and risk
assessment: pathogens" is within that same draft. In the
discussion following the presentation of that group's
conclusions, Akin, speaking to the comparative risk of viral
infection via land application of waste versus person-to-
person contact, said that the American people "... want
their drinking water to be 'risk free' or as close to it as
can be obtained within reasonable economic constraints . . .
that is the key word, 'reasonable'."
The question, therefore, is what constitutes reasonable
cost and reasonable risk? How do we assess each?
As I have before, I suggest considering William Lowrance's
1976 definition Of Acceptable Risk:
A thing is safe if its risks are judged to be accept-
able . . . nothing can be absolutely free of risk . . .
there are degrees of risk and, consequently, there are
degrees of safety . . This definition emphasizes the
relativity and judgemental nature of the concept of
safety. It also implies that two very different
activities are required for determining how safe things
are: measuring risk, an objective but probabilistic
pursuit, and judging the acceptability of that risk
(judging safety), a matter of personal and social value
judgment.
My professional competence is 1
and making some suggestions as
the context of epidemiology and
issue of acceptability of that
asked to address.)
imited to measuring risk
to how one would do this in
of modeling epidemics. (The
risk is not one I have been
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Twenty years ago, I wrote a little paper suggesting
that Newcastle disease virus (NDV) is an ideal model system
for studies of virus epidemiology as the virus can be used
in its natural host and the laboratory can closely simulate
field conditions (Sagik 1964). As it turned out, the same
thought had occurred to the distinguished virologist C.H.
Andrewes (Andrewes and Allison 1961). Some of those old
data may persuade you that this could indeed, with appro-
priate quantitation, represent a useful epidemiological
model enabling us to ascertain both the infective dose and
the probability of overt infection as a function of prior
host exposure. Selection of appropriate viral strains could
serve to refine this model even further.
As I review what I have written, I am bemused to
find that although I agree with Melnick's 1974 thought that
conventional epidemiology isn't worth pursuing any longer
and also with the 1983 Denver Workshop statement that
epidemiological studies no longer remain a high priority
research need, I would like to see someone carry out a
quantitative experimental epidemiological study to place
that last remaining viable virus particle in drinking water
or recreational water or sludge in its proper perspective as
a contributor to the public's health burden, i.e., to
measure risk.
REFERENCES
Andrewes, C.H. and A.C. Allison. 1961. Newcastle disease
as a model for studies of experimental epidemiology.
J. Hyg. London 59:285-293.
Cliver, D.O. 1983. A critique of virology research needs.
In; Proc. Workshop on Research Needs Relating to Soil
Absorption of Wastewater, June 1983, Colorado State
University, Fort Colllins, Colorado.
Dudley, D.J., M.N. Guentzel, M.J. Ibarra, B.E. Moore, and
B.P. Sagik. 1980. Enumeration of potentially pathogenic
bacteria from sewage sludge. Applied Environmental
Microbiology 39:118-126.
Goldfield, M. 1976. Epidemiological indicators for trans-
mission of viruses by water. I_n: G. Berg, H.L.
Bodily, E.H. Lennette, J.L. Melnick, and T.G. Metcalf
(eds.), Viruses in Water, APHA.
Lowrance, W. 1976. Of Acceptable Risk. William Freeman.
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Melnick, J.L. 1976. Social impact. In: G. Berg,
H.L. Bodily, E.H. Lennette, J.L. Melnick, and T.G.
Metcalf (eds.), Viruses in Water, APHA.
Melnick, J.L. 1977. Are conventional methods of epidemi-
ology appropriate for risk assessment of virus
contamination of water? I_n: B.P. Sagik and C.A.
Sorber (eds.), Proc. Conference on Risk Assessment
and Health Effects of Land Application of Municipal
Wastewater and Sludges, Center for Applied Research and
Technology, The University of Texas at San Antonio.
Morrison, S.M. 1983. A critique of microbiology research
needs. I_n: Proc. Workshop on Research Needs Relating
to Soil Absorption of Wastewater, June 1983, Colorado
State University, Fort Collins, Colorado.
Page, A.L., T.L. Gleason, III, J.E. Smith, Jr., I.K. Iskander,
and L.E. Sommers (eds.). 1983. Proceedings of the
1983 Denver Workshop on Utilization of Municipal
Wastewater and Sludge on Land.
Sagik, B.P. 1964. Synthesis and symptomology of Newcastle
disease virus under controlled conditions. Chemo-
therapia 9:104-110.
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ALTERNATIVE APPROACHES TO MICROBIOLOGICAL
RISK ASSESSMENT
by: Charles A. Sorber
Department of Civil Engineering
The University of Texas at Austin
Austin, Texas 78712
INTRODUCTION
Attempts to measure directly the microbiological health
effects related to the various uses and disposal methods of
municipal wastewater sludges have proved to be very expensive.
Further, these types of studies are complicated by a number
of factors including very low infection rates, highly mobile
populations, resistance of participants to cooperation in
long-term studies, and the lack of appropriate methodologies
for environmental sampling and assay of some important
pathogens. These kinds of problems suggest that alternative
approaches to estimating the risk from municipal wastewater
sludges may be more appropriate. Within this context it
appears that well-designed monitoring programs and modeling
hold the most promise.
The use of sentinel animals has been suggested as an
alternative, also. However, results of direct-feeding
studies have been less than encouraging for this approach.
Studies involving the direct feeding of municipal wastewater
sludge to swine, deer, cattle, and other animals have not
demonstrated any major microbiological problems. Recognizing
that the experimental designs used in these studies may be
improved upon and that these animal models may not be
appropriate for estimating microbiological risk to humans,
the fact remains that realistic exposures to humans normally
will be more subtle than direct ingestion of sludge. In
fact, use of the most appropriate animal models may not be
much less expensive (or rewarding) than epidemiological
investigations.
EXPOSURE PATHWAYS FOR NON-OCCUPATIONALLY EXPOSED INDIVIDUALS
In designing any alternate method of risk assessment,
the first step involves the definition of the potential
pathways of human exposure to microorganisms. This has been
done in a number of studies. One such straight-forward
approach has been used recently by the Municipality of
Metropolitan Seattle (Metro 1983). An example of such an
analysis is shown in Figure 1. Obviously, this example can
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Surface
Water
M
I
OJ
Digested Sludge
Sub-Surface Soil
Groundwater
FIGURE 1
Pathways of Microbial Transport From Sludge in
Silviculture Application 1
-------
be modified to accommodate agricultural use of municipal
sludge, composted sludge, landfill of sludge, or any other
use or disposal method.
In general, it appears that the most important pathways
to humans for microorganisms in sludge are through ground-
water or surface water used as either potable water sources
or for contact recreation. Another pathway which may be
important under some conditions involves the agricultural
use of sludge where unprocessed food crops are grown for
direct human consumption. This latter circumstance is both
unpalatable as well as a major potential health risk and,
as such, should be prohibited or at least vigorously
discouraged.
MONITORING
Monitoring of groundwater and surface water can be
useful in estimating both the impact of municipal sludges on
the waters and the potential risk from pathogens. This
approach has been used with limited success in a number of
studies. Clearly, improved methodologies are required to
provide reasonable estimates of the impact of specific
pathogens directly related to sludge.
Barring the availability of economical methodologies
for pathogens, indicator systems can be used. Conservative
indicator systems (nitrate-nitrogen) and, possibly, bacterio-
phage may be appropriate for a first-level effort. Should
these indicators increase significantly above background
(presludge application/use or upstream samples in the case
of surface water sources), monitoring for specific pathogens
can be intensified.
In any case, research is required into the validity
of this approach. Further, efforts should be made to
identify biological indicators appropriate for this type of
moni toring.
MODELING
Another alternative approach to estimating risks to
humans is modeling. This is a more sophisticated approach
than is direct monitoring; however, it may have significant
merit. A number of soil, watershed, and groundwater models
exist. In most cases, they must be modified for use with
pathogens. Unfortunately, the weakest link in any modeling
effort is the quality of data that is,used in the model.
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In modeling microbiological parameters, reliable data
must be developed for specific pathogens to include:
o Effects of a variety ot treatment processes.
o Survival in sludge or sludge/soil matrices.
o Transport in a variety of soils under different
climatic conditions.
o Decay as a function of time, temperature, and other
conditions in soils.
o Estimates of illness outcome due to exposure.
Even without these detailed data, the modeling approach
appears to be reasonable. Interesting ly, participants of
the panel on "Public Health and Risk Assessment: Pathogens"
at the recent workshop on utilization of Municipal Wastewater
Sludge on Land drew one major conclusion (Page et al. 1983):
Workshop participants believe that major resource
allocations should focus on work that would allow a
more accurate prediction of pathogen exposure and
illness outcome through modeling approaches. The
influence of specific actions, e.g., various levels of
pretreatment, on the level of risk could be evaluated
and may indicate more cost-effective treatment/disposal
opt ions.
CONCLUSIONS AND RECOMMENDATIONS
Both monitoring and modeling can be useful alternatives
in microbial risk assessment of the use and disposal of
municipal wastewater sludges. This topic has been discussed
extensively in a number of forums; however, the conclusion
remains the same.
At the recent Workshop referenced above, both the
author of the position paper on pathogens (Gerba 1983}
and the panel on "Public Health and Risk Assessment:
Pathogens" {Page et al. 1983) arrived at some very specific
recommendations for research that are applicable to this
topic. Although this author may have preferred some
rewording, selected recommendations are quoted below as
printed in the draft report in the interest of consistency:
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A. Position paper by Gerba (1983):
1. Development of models based upon virus and site
characteristics for predicting survival and transport
of viruses in the soil that will take into account as
much phenomena as is presently known including long-
range movement as evidenced by the findings of viruses
at considerable depths and distances from wastewater
land-application sites.
2. Studies of virus survival and movement in the soil
designed to test the validity of the above models.
3. Development of improved virus detection methodology
since only one-tenth to one-hundredth of the viruses in
wastewater can at present be detected.
4. Studies of the survival of viruses and protozoan
cysts in storage- and waste-stabilization ponds.
B. Report of the panel on "Public Health and Risk Assessment:
Pathogens" (Page et al. 1983):
Bacteriology
1. Determine survival and regrowth of established
human pathogens (e.g., Salmonella) and newly recognized
waterborne pathogens (e.g., Campylobacter, Yersinia) in
sludge and in soils amended with sludge and wastewater.
2. Improve methods for detection, enumeration, and
assessment of virulence of these pathogens in sludge
and wastewater.
3. Determine effectiveness and mechanism of action of
treatment processes in reducing pathogens in sludge and
wastewater.
4. Determine relevance of existing indicator organisms
as indicators of the presence of new pathogens.
5. Identify factors and determine survival and trans-
location of pathogens and indicator organisms in
sludge-amended soils under different infiltration rates
and in different soils . . .
Parasitology . . .
4. Determine important factors affecting survival
of Ascaris ova in sludge-treated soil and develop
die-off curves under various meteorological conditions.
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Virology
1. Conduct site monitoring studies of survival and
movement of viruses applied to land under wide ranges
of climatic, hydrologic, and waste conditions. Quality
assurance of field data should be given high priority.
2. Determine effectiveness of sewage treatment processes
before land application, especially disinfection, for
virus reduction to acceptable low levels . . .
4. Develop methods to detect those enteric viruses
that are known to cause human illness from fecally-
contaminated water and wastes but are presently
difficult to cultivate or as yet not cultivatable,
e.g., hepatitis A virus, Norwalk-type viruses, and
rotavi ruses.
5. Develop methods of high and defined efficiency
(quality assurance) for the more easily cultivated
enteric viruses in wastewater, sludges, soils, and
groundwater associated with land application systems.
Successful completion of these research tasks is
required for truly effective monitoring and modeling of
microbiological risk assessment related to municipal sludge
use or disposal. Nevertheless, the following research
should proceed even without these necessary refinements:
(1) The validity of monitoring with use of existing
indicator systems should be studied with regard to
the predictability of the presence of pathogens
from municipal sludges in groundwaters and surface
waters.
(2) Modeling of the transport, exposure, and infection
probabilities should be developed for a number of
high probability exposure pathways of pathogens
present in municipal sludge.
REFERENCES
Gerba, C.P. 1983 . Pathogens. I_n: A.L. Page et al.
(eds.), Proceedings of the 1983 Workshop on Utilization
of Municipal Wastewater Sludge on Land, University of
California, Riverside.
Metro. 1983. Health Effects of Sludge Land Application:
A Risk Assessment. Metro Report. Municipality of
Metropolitan Seattle.
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Page, A.L. et al. (eds.). 1983. Public health and risk assessment:
pathogens. Proceedings of the 1983 Workshop on Utili-
zation of Municipal Wastewater Sludge on Land, Univer-
sity of California, Riverside.
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MICROBIOLOGICAL RISK ASSESSMENT OF SLUDGES:
DATA REQUIRED BY EPA
by: Sheila L. Rosenthal
OHEA/U.S. Environmental Protection Agency
(RD-689)
401 M Street, S.W.
Washington, D.C. 20460
I am here as a representative from the Office of
Health and Environmental Assessment (OHEA) of the U.S.
Environmental Protection Agency (EPA). A major function of
this office is to write risk assessments for many of the
program offices in EPA. For example, we provide assessments
for the clean air, clean water, hazardous waste, and pesti-
cide offices of EPA at their request.
The purpose of my talk is to discuss the kinds of
information I believe OHEA will need in order to assess the
risk of adverse health effects due to the presence of
pathogenic microorganisms in sewage sludge after it is
applied to the land.
Risk assessment is a process that organizes information
to come up with solutions for various types of problems.
Examples of problems include health, the economy, insurance,
and the Alaska pipeline. When organized, the information
suggests how likely a certain outcome is and how bad it will
be.
For the most part, OHEA has been asked to perform
risk assessments for chemicals either in pure form or as
mixtures. Some of the health endpoints we are concerned
with include cancer, mutagenicity, teratogenicity, and male
and female infertility. For each chemical we are requested
to assess, we gather the available information pertaining to
the effect the chemical has on each health endpoint. Then,
based on the data available, we come up with a qualitative
or quantitative statement on how much of a problem the
chemical might be. For mutagenicity, the sort of informa-
tion we use includes the ability of a chemical to cause
mutagenic effects in animals, bacteria, and cells in culture.
We also use information on the ability of the chemical to
cause chromosomal effects in humans exposed by an accident
or in the workplace. For the cancer endpoint, epidemiologi-
cal evidence is used whenever available in addition to
results from testing in animals and cells in culture.
There are two major mechanisms by which a substance
can cause disease. In the first, the substance will be
effective (cause disease) only above a certain threshold
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concentration. Below that threshold is the so-called
no-effect level. The dose-response relationship for the
second case involves no threshold. In this case, any
exposure could lead to a toxicolog ical response. Information
at low doses is often not available and extrapolation to low
dose levels is frequently done to determine how much disease
will result from exposure at low doses. The problem is
which model to use. For mutagenicity, because we know the
target molecule and because we know that one event can cause
a mutation, we assume that a no-threshold relationship
exists. However, for cancer the situation is not so clear
because the mechanism(s) of cancer causation is not known.
For a particular chemical, will one event be sufficient to
result in cancer or will that chemical cause cancer only
after multiple events have occurred? Because there is some
evidence that, for certain chemicals, the initiative stage
of carcinogenesis may be the result of a mutagenic event,
the Carcinogen Assessment Group uses extrapolations based on
a no-threshold model to assess the risk of exposure to car-
cinogens that are probably also mutagens.
Another major piece of information necessary for
risk assessment is exposure. There are three major routes
of exposure - inhalation, ingestion, and dermal. Factors
taken into consideration in determining total exposure are
the duration of exposure and the concentration of the
substance in the air, water, or other media. By using
information on health hazards coupled with exposure data for
humans, it may be possible to estimate human risk.
I think a major issue that has to be considered before
EPA can do a microbiological risk assessment on the agri-
cultural use of sewage sludge is the variability in the
numbers and types of organisms found in sewage sludges.
This is a situation that is very different from assessing
risks due to exposure to a chemical.
I am not sure what approach EPA would ultimately use in
performing a microbiological risk assessment of sludge. The
data required for doing a risk assessment may depend on the
approach used. But as a first step, I will briefly mention
the kinds of data that would be useful in an approach to
risk assessment that is similar to that used by Sydney
Munger in her Metro assessment for the city of Seattle.
(1) How was the sludge treated before it was applied
to the land? Various treatment methodologies have
been developed and include aerobic-thermophilic
digestion, anaerobic-mesophilic digestion,
composting, irradiation, and so forth. How
effective are the treatment procedures in reducing
the numbers of pathogens in the sludge? How many
of each type of pathogen are left?
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(2) What types of microorganisms are present in
the sludge? Three major classes of pathogenic
microorganisms are of concern in sludge.
(a) Bacteria, such as Salmonella, Shigella,
Vibrio, Yersinia, and Campylobacter. These
organisms cause typhoid, dysentery, cholera,
gastroenteritis, and food poisoning.
(b) Viruses, such as poliovirus, coxsackievirus,
hepatitis type A, Norwalk virus, and rotavirus.
These viruses can cause meningitis, paralysis,
diarrhea, respiratory disease, hepatitis, and
gastroenterit is.
(c) Parasites, such as protozoa and worms. These
organisms cause amoebic dysentery, diarrhea,
colonic ulceration, and anemia.
Monitoring sludges for every type of organism is a
big job. In order to simplify this task, organisms
that are indicators of each class are often
monitored rather than every type of organism in
that class. For example, Salmonella and coliform
bacteria have been employed as indicators for
the presence of pathogenic bacteria. How valid is
this practice of using indicators for enumerating
the numbers of pathogens present in sludge and for
determining their survival and movement in the
environment after the sludge is applied to the
land?
Another concern in this area of identifying
pathogenic organisms in sludge is the potential
for new organisms from the biotechnology industry
to adversely affect human health. Industrial
biotechnology laboratories are not regulated and
the possibility exists that a "new" organism could
be dumped down the sink and end up in the sludge.
Such organisms could have altered survival char-
acteristics. This is considered to be a low
probability/high impact situation — i.e., it is
very unlikely to occur, but, if it did occur, the
impact could be large. This would be of concern
only in municipalities where biotechnology firms
exist -- Cambridge, Massachusetts, for example.
(3) What crops will be grown on sludge-treated
soil? Will they include food that is generally
eaten raw? How long after treatment will the food
crops be harvested?
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(4) What is the fate of human pathogens in the environ-
ment? How well do they survive after the sludge
is applied to the land? How deep into the soil
will they penetrate and what lateral movement
would be expected?
(5) To assess the probability of human disease from
enteric pathogens via exposure to surface or
groundwater after land application of sludges,
information is required concerning how well the
surface run-off is controlled. Also, what is the
depth of the groundwater in the area of the
application site? Information pertaining to the
nature of the soil to be treated with sludge would
also be useful — e.g., how pervious is the soil?
(6) To what extent are the various pathogens
aerosoli zed?
(7) How many people would be exposed, for how long,
to what number of microorganisms, and by what
route? Exposure can occur as a result of direct
contact with sludge-treated soil, aerosolization
from spray application of sludge, and ingestion of
contaminated surface and groundwaters.
(8) What is the frequency of disease in people exposed
to pathogenic microorganisms? One approach that
has been used for obtaining this type of informa-
tion is to determine the minimum infectious dose
for each pathogen present in the sludge. The
minimum infectious dose for some viruses and worms
(Ascaris) can be as low as one organism. For
Salmonella, the minimum infectious dose can be as
low as 100 bacteria, and for Giardia, as low as 10
cysts. The frequency of disease resulting from
infection depends in part on the immune state of
each infected individual. This information may be
difficult to quantitate. One approach would be to
do a worst-case estimate.
In order to perform an assessment of the microbiological
risk from exposure to sewage sludge, we need to obtain
information to fill many data gaps, some of which I have
mentioned above. Most of the data gaps have been identified
and were listed in the Proceedings of the 1983 Workshop on
Utilization of Municipal Wastewater and Sludge on Land. One
approach, which has already been done and was mentioned in
the 1983 Proceedings, is to determine the relative risk of
land application of sludge compared with the risk from some
other disposal method, such as discharge to a stream. It
was found that the risk to the public from exposure to
sludge is the same for these two disposal methods.
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ORGANIZATION, RESPONSIBILITIES, VIEWPOINTS,
AND PERSPECTIVES ON PATHOGEN CONTROLS
by: Charles S. Spooner
Acting Director, Sludge Task Force
U.S. Environmental Protection Agency (WH-556)
401 M Street, S.W.
Washington, D.C. 20460
Since the Spring of 1982 the Sludge Task Force has
worked to redefine and organize the U.S. Environmental
Protection Agency's (EPA) approach to sludge management.
Just prior to this, the regulatory efforts of the Office of
Solid Waste had been diverted from developing sludge regula-
tions to hazardous waste — leaving sludge regulations
incomplete amid uncertainty and controversy. The Task Force
is in the process of completing arrangements to resume an
active role in sludge management. It will do this by
issuing guidelines, planning a regulatory program, and by
issuing a Policy in the near future.
The Task Force has drafted, and most EPA offices have
reviewed, a Policy on Municipal Sludge Management that
clearly states what we believe should be the role of EPA,
the states, and local governments and what values we
believe should guide management decisions. The Policy
states:
(1) That EPA will actively promote those sludge
management practices that provide for the beneficial
use of the energy, nutrient, and soil conditioning
values in sludge consistent with adequate protection
of the public health and environment.
(2) That each level of government has specific roles
in sludge management:
• EPA will regulate and guide sludge management
and assist through research.
• State governments have a primary role in
regulating local sludge disposal and reuse and
in facilitating the planning and operation of
local systems.
• Local governments have the freedom to choose
from available management options, but also the
responsibility to do so, and the responsibility
to maintain adequate management capacity.
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The Task Force has concluded that regulatory programs
should be implemented through the States, even though the
legislative intent of section 405 is far from clear on their
role. This means that State opinions and State acceptance
of EPA's recommendations and background work will continue
to be important.
The Task Force has set forth some general criteria for
deciding when to issue Federal technical controls on
and disposal of sludge. Pathogen controls fall into
category of Federal concerns we have identified, and
clearly our opinion that Federal technical standards
pathogens are appropriate.
Pathogen controls exist in 40 CFR 257. They apply to
land-applied sludges. It is our conclusion that these
regulations must either be explicitly supported or altered.
We cannot just leave these requirements in place, because we
have announced our intention of filling the gap in our
regulatory structure caused by the absence of regulations
covering non-food-chain land spreading. Pathogen controls
needed for these new regulations will doubtless unmask the
poor justification for our existing regulations. Requirements
in 40 CFR 257 define technologies that provide what are
called "processes to significantly reduce pathogens" (PSRP)
and "processes to further reduce pathogens" (PFRP); each
allows what it calls "equivalent" technologies to be used.
Waiting periods before public access is allowed are also
defined.
the use
the
it is
on
The Task Force has examined the regulatory record for
these requirements, and talked to those who were involved in
the preparation of these regulations in the late seventies,
and, to its dismay, finds little in the record to justify
the requirements in place. It found only informal procedures
for determining the "equivalence" that will allow other
technologies to be substituted by localities willing to
comply. The Task Force suspects that this is due both to
poor recordkeeping in the past and to the fact that the
requirements are based on undocumented judgements that we
may want to reconsider.
It would be sad to find that as the Office of Water is
about to reassume regulatory preparation, it must ask that
we spend research time retracing the logic of the past in
order to defend the regulatory action we need for the future.
While we are disappointed that the cupboard of regulatory
justifications is bare, we think that we can use this period
to examine practical alternatives in the existing regulations,
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not just different numbers, or an expanded list of technolo-
gies. Other approaches might include performance standards
instead of technology-based requirements or specified
waiting periods. I think the idea of allowing local risk
assessments and risk management plans may be an alternative
approach worth further assessment.
Another -- and not surprising -- concern of the Task
Force is that it has also found that the pathogen controls
in existing regulations are widely misunderstood by the
regulated community, and even by the State regulatory
agencies. Dr. Lue-Hing can, I am sure, address the concerns
for these regulations that he and the Association of Metro-
politan Sewerage Agencies expressed to the Task Force last
March.
The Task Force has been concerned that the States have
only partially accepted the regulatory requirements of 40
CFR 257 even though they have had over 4 years. Our
recent analysis shows that 12 states have not adopted PSRP
or PFRP requirements and 9 states have adopted only a
portion of these regulations, even though 29 states have
adopted them.
We think that this partial acceptance is proof that our
regulations have not enjoyed the understanding that successful
regulations of the future must have before we can count on
the kind of national sludge management program we are now
preparing to implement.
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ASSESSING POTENTIAL HEALTH EFFECTS
OF LAND-APPLIED SEWAGE SLUDGE
by: Rufus L. Chaney
USDA-Agricultural Research Service
BWM&ORL, Bldg. 0 08, BARC-W
Beltsville, Maryland 20705
The agricultural community is one group that could be
affected if land application of municipal sludge comprised a
health risk. Thus, the U.S. Department of Agriculture
(USDA) (including Agricultural Research Service, Soil
Conservation Service, Extension Service, Forest Service,
etc.) has cooperated with the U.S. Environmental Protection
Agency (EPA) and the Food and Drug Administration (FDA) to
evaluate the potential for risk from land-applied sludge.
USDA wants to assure that sludge utilization on privately-
owned land will not negatively affect the health of farm
workers, the safety and quality of food and feed crops
produced, or long-term soil fertility. Although EPA has the
primary Federal responsibility for regulating sewage sludge
disposal and utilization, USDA's responsibilities toward
soil, crops, and farm workers require that we be interested
in, and advise EPA on, these practices. EPA has sought
advice from USDA and the State Experiment Stations at least
in part because the Agricultural Extension Service advises
farmers directly and could affect sludge acceptance by
farmers.
This review of USDA views is not to be taken as an
Agency Position. When formal Agency statements are prepared,
all parts of USDA are allowed to review the proposed text
before it is ready for official signature. The process
requires several months at a minimum, and it is reserved for
important documents. Rather, this is a summary of results
and concerns of USDA scientists after 12 years of intensive
sludge research and evaluation. It reflects the views of
researchers and of extension and other advisory groups in
USDA.
USDA has cooperated with EPA in developing guidance and
regulations regarding municipal sludge since 1972. USDA's
formal viewpoints, approved at the Secretary or Assistant
Secretary level, have been communicated to EPA on several
occasions. USDA provided soil metal cumulative applications,
and advised on waiting periods for pathogen inactivation for
the EPA "Municipal Sludge Management: Environmental Factors"
(1977). USDA participated during development of the "Criteria"
(1979) and provided formal review comments. USDA cooperated
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in development of the EPA-USDA-FDA 1981 Joint Policy State-
ment No. SW-905 "Land Application of Municipal Sewage
Sludge for the Production of Fruits and Vegetables. A
Statement of Federal Policy and Guidance". The Statement
includes longer waiting periods for pathogens, and recommends
sludge quality limits for cadmium (Cd), lead (Pb), and
polycholrinated biphenyls (PCBs). Our laboratory prepared
an EPA bulletin for composting sewage sludge which presents
appropriate management and monitoring to assure pathogen
inactivation, and specific sludge compost quality standards
for a marketable product (no site of application regulations).
USDA's approach to management/regulation of land
application of municipal wastewater treatment sludges
includes a number of points, not all of which are included
in EPA regulations or guidance:
(1) Where possible, publicly owned treatment works
(POTWs) should avoid excessive treatment costs, or processes
which reduce the fertilizer value of sludge. These include
CI2 treatment and Ca(OH)2 treatment of digested sludge
to pH above 10, which remove sludge nitrogen (N). Ca(OH)2
can mineralize sludge N, especially for digested sludge.
CaCC>3 applied to cropland can control soil pH at much
lower cost than excessive Ca(OH)2 added during sludge
dewatering.
(2) POTWs should inject sludge to conserve sludge N,
avoid malodor and unsightly deposits on crops, and to reduce
potential ingestion of pathogens, toxic elements, and toxic
organics by grazing livestock (consumption of sludge on the
soil surface or sludge-covered forages). Further, use of
sludge injection allows much better acceptance by the
general public than other application technology. Both
liquid and dewatered (up to 16 to 18 percent) sludges are
presently being injected in the U.S. Injection does conserve
NH4-N, which both reduces sludge annual application rates
and prolongs the useful life of an application site. I
believe the greater acceptance, prevention of direct sludge
exposure, and conservation of sludge fertilizer value
resulting from sludge injection fully justify strong support
of this technology over others even though the costs are
somewhat higher.
(3) USDA continues to want Federal regulations to
limit application of phytotoxic elements [zinc (Zn), copper
(Cu), nickel (Ni), etc.], not just Cd and Pb. EPA has
provided the USDA advice in their guidance, but not regula-
tions. Most states have adopted limits on phytotoxic
elements even though EPA has not acted. Although further
research may be required to achieve desired precision in the
regulation of phytotoxic elements, these rules are still
needed.
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(4) USDA has special concern about the highest human
risk route of sludge "disposal", Distribution and Marketing
(D&M). Farmers and gardeners are still allowed to obtain
sand bed dried sludges in many cities. Often these sludges
are high in one or several toxic elements, may be high in
organics, and have not received a Process to Further Reduce
Pathogens (PRFP). In 1977, the Government Accounting Office
(GAO) warned EPA about the need to act on this unregulated
practice. EPA Region 5 had to order Chicago to cease
distribution of Nu-Earth to home-owners and community
gardeners because this sludge contained 200 parts per
million (ppm) Cd. Although well-developed revised draft
regulations were nearly ready for publication by January
1981, sludge D&M remains unregulated.
Several states have had to proceed in the absence of
D&M Regulations from EPA. These states had new major sludge
composting facilities, and worked to accommodate the best
available advice and allow D&M of properly composted sludge.
Maryland and Ohio have formal D&M regulations, while Virginia
Pennsylvania, and other states are informally regulating
D&M. States have needed D&M regulations since 1973, the
beginning of modern work to create appropriate regulations
on municipal sludge.
(5) USDA now believes research has provided evidence
showing that not only cumulative metal application, but also
sludge quality (sludge metal concentration) influences the
potential for metal uptake by crops (Chaney et ai. 1982),
Stypersk et al. 1982, Logan and Chaney 1984). We have
always known that the potential for inadvertent excessive
metal application was greater for high metal sludges (small
loadings can exceed guidance). Further, it is clear that
potential sludge benefit is inversely proportional to sludge
metal concentration where cumulative metal guidelines are
followed. We are happy that research has now showed a
technical basis, rather than only having "common sense" on
our side. The firm evidence on Cd appears to be extended to
Zn, Cu, and Ni by already published research. More work is
needed to see if some low level of these metals in sludges
prevents excessive plant uptake or phytotoxicity, and would
thus allow higher cumulative applications for low metal
sludges.
The sludge quality evidence appears to extend to toxic
organics as well. PCB adsorption by soils is increased by
sludge application (Fairbanks and O'Connor 1980). With
normal low PCB sludges, one cannot detect PCB residues in
carrots, the best PCB-accumulator food crop (Lee et al.
1980). Sludge quality has not been studied regarding direct
ingestion of sludges, but should contribute at least somewhat
to lower toxic organic absorption by livestock ingesting
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equal amounts of a compound in different amounts of sludge
dry matter.
LJSDA has recommended sludge quality regulations for
many years. Certainly this approach is needed in any sludge
D&M regulations. It is also needed as a part of the "Criteria",
These should be extended to organics other than PCBs [other
persistent chlorinated hydrocarbons, polyaromatic hydrocarbon
(PAH) compounds, etc.] as soon as the need for regulations
is established.
(6) USDA believes scientists have learned much about
research methodology for sludges and soil in the last 12
years. New EPA research on toxic elements and organics
should take this into consideration. Excessive sludge
application to attain higher element or compound loading
rates can cause temporary false high plant uptake (see Logan
and Chaney 1984). Rapid biodegradation can cause anaerobic
conditions. Degradation byproducts and excessive chloride
and sulfate salts can increase soluble metals and toxic
organics, and thus facilitate diffusion from soil to plant
tissues. If rates higher than needed to supply crop require-
ments of N are used, a longer study or repeated plant growth
periods are required to realistically assess potential for
plant uptake. Errors due to pot studies, rather than field
studies, and appropriate methods for greenhouse studies have
been reported (see Logan and Chaney 1984). All this, plus
sludge quality effects, need to be considered in all future
research regulations.
(7) In the end, bioavailable element or compound
levels are what should be regulated. Interactions among
elements and with sludge sorption capacity can reduce net
absorption of elements and organics by animals. Further,
interactions can alter biologic responses (see Hansen and
Chaney 1984). Chronic exposure to practical diets containing
crops with levels of compounds or elements obtained by
predictable poor management and by recommended management
should be tested. For ingested sludge, oils, other adsorbing
constituents, and interactions among elements in ingested
sludge can sharply reduce bioavailability of sludge elements
and compounds. Similarly, organic matter in natural waters
sharply reduces bioavailability of added PAH (McCarthy
1983).
(8) USDA believes pretreatment has been successful in
reducing undesirable levels of elements and organics in
sludges, even for major metropolitan areas. Washington,
D.C., Philadelphia, Pennsylvania, and Baltimore, Maryland,
(and many small towns) have used pretreatment to obtain
public acceptance of sludge utilization in agriculture.
Modern countercurrent rinsing and electrolytic recovery
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have led to cost savings by platers. One Cd plater reports
he now purchases 10 percent as much Cd for the same level of
production because electrolytically recovered Cd is recycled
and replaces purchases. Pretreatment facilities quickly
repay their costs. EPA should be proud of their role in
developing these new technologies and advertise their
effectiveness, even though pretreatment is not always
politically acceptable.
(9) Research identified a very substantial error in
risk assessment when soluble salts of elements were used to
simulate sludge-borne elements (see Logan and Chaney 1984).
Further, addition of soluble metal salts to sludges also
overestimates potential for risk. Only sludges with incor-
porated metals, and leached and incubated to allow removal
of soluble salts and degradation of unstable organic matter
aerobically, appear to simulate long-term field trials. EPA
should expect similar errors with toxic organics, and
require experimental protocols to avoid these repeatedly
identified errors.
(10) After attending this sludge workshop, I wanted to
share my PCB risk assessment model. As for Cd, I believe
the garden scenario (sludge product used in garden, or
permitted field converted to building site with garden)
provides the greatest potential for risk. Fries and Marrow
(1981) found PCBs reach plant shoots by volatilization, not
by plant uptake and translocation. The higher the number of
chlorines, the stronger the adsorption and the lower the
vapor pressure. Thus, lower chlorinated PCBs were more
volatilized, but only equally adsorbed to soybean foliage.
Foliage reached about 10 percent of the soil PCB residue
level. (See Fries 1982 for forage-crop/livestock risk
assessment.)
One study looked at PCB uptake by carrots from a low
organic matter (0.6 percent) sandy loam soil (Iwata et al.
1974). Commercial Arochlor 1254 was applied at extremely
high levels, 100 ppm (in 0 to 15 centimeters soil), in the
field. 'Goldinhart' carrots were grown with normal field
culture practices. For the environmentally persistent 5-
and 6-chlorine isomers, unpeeled fresh carrots were about
4.9 percent of the soil level. Peeling removed 14 percent
of the fresh weight and 97 percent of the PCB. Peeled fresh
carrots were 0.16 percent of the soil PCB level.
One might apply these results to "sludge". The median
PCB level in the Michigan sludge survey was not-detectable
(less than 0.6 ppm dry sludge). Presuming one adds 10 Mg
sludge solids per hectare per year (solids/ha/yr) as fertilizer
for corn, one would apply less than 6 grams PCB/ha/yr (adds
less than 0.3 parts per billion (ppb) PCB per year to the
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soil). For a sandy, low-organic matter soil, unpeeled
carrots should contain less than 0.15 ppb PCB (fresh weight
basis) and peeled carrot less than 0.005 ppb PCB (fresh
weight). For higher soil organic matter, sludge-applied PCB
would achieve proportionally lower residues in carrot.
Commercially processed carrots are normally peeled to remove
soil and existing pesticide residues in carrot peels. Thus,
remarkably low potential human PCB exposures would be
predicted for recommended sludge utilization practices. The
study by Lee et al. (1980) used 112 Mg sludge/ha; the sludge
contained 0.93 ppm PCB. "No PCBs were detected in the
sludge grown carrots." Further, as noted above, sludge
should reduce potential PCB uptake by increasing the PCB
adsorption capacity of the soil. Other root crops are not
nearly as good PCB accumulators as carrot (Moza et al. 1979).
Although this realistic scenario suggests great pro-
tection of the food chain from sludge-applied persistent
toxic organic compounds, I believe more research is needed.
Other crops, and many other compounds (including non-
persistent biodegradable compounds) need to be studied to
learn whether present waiting periods developed for pathogens
should be extended to toxic organic compounds present in
some sludges. As for pathogens, the focus has to be on
waiting periods because sludges will always contain some
toxic organics.
The reports on PAH compounds in composted (refuse +
sludge) amended soils by Ellwardt (1977) and by Neudecker
(1978) indicate considerable protection from PAH as well.
Because persistent PAH compounds are strongly adsorbed,
uptake by gaseous diffusion to shoots or tubers is the
expected route of entry to foods. Peeled carrots are low in
PAH. Air pollution contamination of foliage crops is a much
more important source of food enrichment; of course, cooking
practices dominate in human exposure to PAH. Thus, sludges
incorporated into soils allow little potential for human PAH
exposure.
(11) One of the biggest problems with public acceptance
of sludge utilization on cropland is the lack of needed
monitoring and record keeping. The food processing industry
has advised EPA, FDA, and USDA that lack of needed regula-
tions and enforcement require them to not purchase food
crops grown on sludge-treated fields. The food industry
will never advertise "crops grown on sludge", but their
concern about meeting soil metal levels and pathogen
inactivation waiting period requirements is valid. Until a
company or potential land purchaser can check with a state
office and learn whether sludge has been applied to a field
(how much, when, and what quality), the system is not
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adequate. The USDA-ASCS field identification number may be
the best present public identifier for a field. No state
presently has full enforcement of even today's inadequate
regulations.
REFERENCES
Chaney, R.L., S.B. Sterrett, M.C. Morella, and C.A. Lloyd.
1982. Effect of sludge quality and rate, soil pH, and
time on heavy metal residues in leafy vegetables. In:
Proc. Fifth Annual Madison Conf. Appl. Res. Pract.
Munic. Ind. Waste. Univ. Wisconsin-Extension, Madison,
Wisconsin. pp. 444-458.
Davis, R.D., G. Hucker, and P. L'Hermite (eds.). 1983.
Environmental effects of organic and inorganic contami-
nants in sewage sludge. D. Reidel Publ. Co., Dordrecht,
Holland. 257 pp.
Ellwardt, P.-C. 1977. Variation in content of polycyclic
aromatic hydrocarbons in soil and plants by using
municipal waste composts in agriculture. In: Soil
Organic Matter Studies. Vol. II. Int. Atomic Energy
Agency, Vienna, Austria. pp. 291-298.
Fairbanks, B.C., and G.A. O'Connor. 1980. Adsorption of
polychlorinated biphenyls (PCBs) by sewage sludge
amended' soil. (Abstract.) In: G. Bitton et al.
(eds.), Sludge-Health Risks of Land Application. Ann
Arbor Science Publications, Inc., Ann Arbor, Michigan,
p. 346.
Fries, G.F. 1982. Potential polychlorinated biphenyl
residues in animal products from application of contami-
nated sewage sludge to land. J. Environ. Qual. 11:14-20.
Fries. G.F., and G.S. Marrow. 1981. Chlorobipheny1 movement
from soil to soybean plants. J. Agr. Food Chem. 29:757-759.
Hansen, L.G., and R.L. Chaney. 1984. Environmental and
food chain effects of the agricultural use of sewage
sludges. Rev. Environ. Toxicol, (in press).
Iwata, Y., F.A. Gunther, and W.E. Westlake. 1974. Uptake
of a PCB (Arochlor 1254) from soil by carrots under
field conditions. Bull. Environ. Contam. Toxicol.
11:523-529.
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Lee, C.Y., W.F. Shipe, Jr., L.W. Naylor, C.A. Bache, P.C.
Wszolek, W.H. Gutenmann, and D.J. Lisk. 1980. The
effect of a domestic sewage sludge amendment to soil on
heavy metals, vitamins, and flavor in vegetables.
Nutr. Rep. Int. 21:733-738.
Logan, T.J., and R.L. Chaney. 1984. Utilization of municipal
wastewater and sludge on land — metals. I_n: Page,
A.L., T.L. Gleason, J.E. Smith, I.K. Iskandar, and L.E.
Sommers (eds.), Proceedings of the 1983 Workshop on
Utilization of Municipal Wastewater and Sludge on Land.
University of California, Riverside. pp. 235-326.
McCarthy, J.F. 1983. Role of particulate organic matter in
decreasing accumulation of polynuclear aromatic hydro-
carbons by Daphnia magna. Arch. Environ. Contam.
Toxicol. 12:559-568.
Moza, P., I. Scheunert, W. Klein, and F. Korte. 1979.
Studies with 2,4',5-trichlorobiphenyl-14C and 2,2',4,4',
6-pentachlorobipheny1- C in carrots, sugar beets,
and soil. J. Agr. Food Chem. 27:1120-1124.
Neudecker, C. 1978. Toxicological long-term animal feeding
studies on carrots cultivated with composted garbage
and sewage sludge. (In German.) Qual. Plant. 28:119-134.
Stypersk, V.P., D. Sauerbeck, and F. Timmermann. 1982.
Cd-availability in differently treated soils depending
on its quantity and forms of binding. (In German.)
Landwirtsch. Forsch. Sonderh. 39:183-195.
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SUMMARY OF THE DISCUSSION SESSION ON THE
MICROBIOLOGICAL HEALTH EFFECTS OF SLUDGE DISPOSAL
by: Walter Jakubowski
HERL/U.S. Environmental Protection Agency
26 West St. Clair Street
Cincinnati, Ohio 45268
In this portion of the workshop, the objective was to
coordinate the U.S. Environmental Protection Agency Health
Effects Research Laboratory's research planning in Micro-
biology with the regulatory and sludge management needs and
activities of relevant Agency offices. The outcomes or
health effects of infection with pathogens were not issues
— the symptoms and diseases, generally of an acute nature,
produced by pathogenic agents are well known. When a
susceptible host is exposed to viable pathogens, infection
may or may not ensue, depending upon a variety of host
resistance and organism virulence factors. If an infection
does occur, it may be either with or without the production
of symptoms in the infected host.
The primary health effects issue concerning pathogens
in sludge is determining the level or probability of infection
or disease associated with the various disposal options.
The participants agreed that epidemiological measurement of
infection and disease rates associated with disposal of
sludge by land application through silviculture or agriculture
use would probably not be feasible. Sludge disposed of by
these options is subjected to Processes to Significantly
Reduce Pathogens (PSRP) and restrictions are placed on
public access to the sites, type of crop, and length of time
between application and unrestricted use. Under these
conditions, the identification of a suitable exposed population
for study and the characterization of their exposure would
be extremely difficult. In addition, such studies would be
very expensive, lengthy, and have a low probability of
producing interpretable data.
The epidemiological approach, however, may be applicable
to measuring the health effects of pathogens in sludge
utilized in distribution and marketing (D&M) (give-away and
sale) programs. This sludge must be subjected to Processes
to Further 1Reduce Pathogens (PFRP). Although these are
disinfection processes, the product is not sterile and data
are needed on the pathogen content of these sludges as used
by the consumer. Since the consumer has close contact with
the product, it may be possible to design a satisfactory
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epidemiological study if pathogens can be detected in these
sludges. The participants agreed that D&M programs, of all
the sludge disposal options, should be assigned the highest
priority as an area for study of pathogen health effects.
There was considerable discussion on how to obtain
pathogen health effects data on disposal of sludges
produced through PSRP and PFRP in the absence of an approach
that actually measures infection and disease. It was agreed
that risk assessments could be developed similar to that
performed by Seattle Metro for disposal of sludge by the
silviculture, compost, and land reclamation options. This
approach takes into consideration the particular disposal
option, the concentrations of pathogens in the sludge, fate
and transport, potential exposure, and infectious dose.
This approach apparently has been successful in the Seattle
area for obtaining resident, state, and local authority
approval for disposal of sludge by the silviculture option.
To apply this approach on a national basis, however, requires
resolution of a number of questions including:
(1) What model should be used in the risk assessment?
The model used in Seattle may be too simplistic or
incomplete for universal application. On the
other hand, the model developed by BDM Inc. under
the "Sewage Sluge Pathogen Transport Model Project"
(EPA Project Summary 600/S1-81-049) may be too
complex. If the model requires a number of factors
for which the precision is low or uncertain, the
resulting assessment could be meaningless. Whatever
model is chosen must be subject to verification.
(2) Must the risk assessment be site specific? One
region of the country may have a higher endemic
level of certain enteric pathogens than another
region. Within the same region, and even within
the same municipality, the pathogen content of
sludge may vary, e.g., if a particular treatment
plant receives abattoir wastes.
(3) Is is possible to designate "bad actor" pathogens
in sludge? Performing a risk assessment for every
known pathogen that might occur in sludge would be
costly and impractical because of the large number
of enteric pathogens and the unavailability of
adequate quantitatiave methods for many of them.
Some pathogens may be of greater concern than
others because of the severity of the disease they
produce, their concentrations in sludge, their
survivability in the environment, or their low
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infectious dose. Attempts should be made to
develop key pathogens or groups of pathogens that
may be measured, e.g., "total enteric animal
virus", "total enterobacteria", "total ova and
parasites". In addition, the use of indicator
groups, such as bacteriophages, should be investi-
gated .
(4) Can "worst case" situations be identified for
performing risk assessments? Additional information
is needed on the daily, seasonal, and geographic
variations in pathogen content of sludges. The
determination of the range of pathogen content in
various sludges may simplify preparation of the
technical standards and writing of the regulations
by delineating the risk associated with these
ranges. On the other hand, "worst case" evaluations
may be unnecessarily restrictive and might deter
public acceptance.
These questions were discussed at some length during
the workshop and they need to be taken into consideration
in the development of risk assessments for sludge disposal
options. There was general agreement that risk assessments
can be performed now using available data. Some areas are
known to need improvement, such as the development of
quantitative methods for protozoa and helminths in sludges,
and the fate and transport of pathogens. Much research
needs to be performed on the effects of environmental
factors, e.g., precipitation, temperature, and solar radiation,
on survival and movement of pathogens. This knowledge is
basic to the exposure modeling portion of risk assessment
since it allows site-specificity. The process of performing
the risk assessment should aid in identifying additional
data gaps and in resolving the above questions.
One additional approach to obtaining health effects
data on pathogens in sludge was briefly discussed — the use
of sentinel animals. The opinion was offered that this
would not be a fruitful approach because of the variety of
pathogens involved, the difficulty in selecting and maintaining
suitable hosts at appropriate sites, and the uncertainty in
extrapolating animal exposure and infection data to humans.
No contrary opinions were expressed.
Based in part upon the success of this meeting, addi-
tional meetings of experts were scheduled to determine
contaminants of concern for the various use and disposal
options.
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RECOMMENDATIONS FOR MUNICIPAL WASTEWATER
SLUDGE HEALTH EFFECTS RESEARCH: MICROBIOLOGY
by: Walter Jakubowski
HERL/U.S. Environmental Protection Agency
26 West St. Clair Street
Cincinnati, Ohio 45268
The workshop did achieve the objective of identifying
doable microbiological health effects research. Although it
did not develop a prioritized multi-year research plan, it
did provide the basis for developing a rational, cohesive
plan in the context of U.S. Environmental Protection Agency
regulatory needs. The sharing of viewpoints, responsibilities,
and needs of the various cognizant offices and authorities,
both inside and outside the Agency, was a necessary first
step that will be built upon as the planning process continues.
Specific research needs on the health effects of
pathogens in sludge concern providing data for risk assessment
and conducting an epidemiological study of distribution and
marketing (D&M) programs. Needs that can be addressed by
the Health Effects Research Laboratory (HERL) are in the
following areas.
(1) Development and evaluation of quantitative methods
for protozoa and helminths in sludge and sludge-soil
mixtures.
(2) Fate and transport of pathogens.
(3) Minimum infective dose.
(4) Epidemiological study of D&M programs.
Additional information needs to be developed by the
Municipal Environmental Research Laboratory (MERL) on the
efficacy of Processes to Significantly Reduce Pathogens
(PSRP) and Processes to Further Reduce Pathogens (PFRP)
treatment practices and on the daily, seasonal, and regional
variation in pathogen content of such sludges. An evaluation
of conservative indicators (e.g., nitrate, bacteriophages)
for pathogens in sludges is also needed.
Preparation of risk assessments is the responsibility
of the Office of Health and Environmental Assessment (OHEA)
and the Environmental Criteria and Assessment Office (ECAO).
HERL microbiologists should work with these offices in
selecting appropriate models and in providing data for risk
assessments. Validation of risk assessment models will be
requ ired.
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SECTION III
ORGANIC CHEMICALS HEALTH EFFECTS OF
MUNICIPAL WASTEWATER SLUDGE DISPOSAL
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ORGANIC CHEMICALS SESSION SUMMARY
The Organic Chemistry session covered the following
top ics :
• The quantity, composition, and variability of the
organic chemical constituents of municipal
wastewater sludge.
• The behavior and fate of the chemicals after sludge
is applied to land.
• The potential human health risks from chemical
exposure:
- biochemical changes
- histological changes
- physiologic responses
- genetic damage
• Methods for realistically estimating the potential
risk from organics in land-applied sludge, based
on:
- modeling
- epidemiologic methods
First, Charles S. Spooner, Acting Director of the EPA's
Sludge Task Force, presented an overview of the progress the
Task Force has made in documenting the importance of toxic
compounds in wastewater sludge.
Lee W. Jacobs, from Michigan State University, then
presented an overview of the "Types and concentrations of
organics in municipal sludge", based on an analysis of
sludges from 204 municipal wastewater treatment plants for
73 organic chemicals. The data indicate "th^t sludges can be
highly contaminated with organic chemicals, but that the
overall degree of organic chemical contamination of sludge
appears to be a manageable problem.
The fate of any of these synthetic organic chemicals is
of concern when municipal wastewater sludge is applied to land.
Lewis M. Naylor of Cornell University examined one initial
step in chemical transport in his paper "Transfer of synthetic
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organics from sludge to soil". He reviews an EPA interim
report on the occurrence and fate of the 129 priority pollu-
tants in the wastewater and sludge from 20 publically owned
treatment works that represented a cross-section of the
types of facilities and wastewater and sludge characteristics.
Then, based on a hypothetical rate of application of sludge
to land, and the reported concentration of organics, he
projected the resultant priority pollutant application rate.
Assuming that all the chemical is transferred to the soil,
even for the most concentrated pollutants the derived
application rates are not greater than the recommended
application rates for agricultural pesticides. A diet
scenario was developed to consider the health hazards due
to intake of organic priority pollutants and indicated that,
except possibly where sludge is consumed directly in large
amounts, consumption of contaminated crops will not normally
exceed the acceptable daily dose of organic priority pollut-
ants. A limitation of this work is that it was based on
acute toxicity data, rather than assuming carcinogenicity of
the compounds he discussed. However, he did use worse case
analysis on the acute toxicity data.
After Nay lor examined the initial input of organics
from land-applied sludge to soil, Michael R. Overcash of
North Carolina State University discussed the subsequent
"Stability, mobility, and bioactivity of organics in soil".
He examined the behavior of organics in the terrestrial
system that affect their eventual state and fate, specif-
ically: stability, inactivation through binding, mobility,
and bioavailability.
The next three presentations discussed various approaches
to investigating sludge organics: feeding studies; mutagen-
icity studies; and fractionation and identification of the
specific organic constituents.
John G. Babish of Cornell University summarized the
results of 30 research investigations into the movement
of toxic materials (heavy metals and organic chemicals) from
sludge to animals. Determining the magnitude of this
movement is a step in evaluating the potential for adverse
human exposure from land-applied sludge. His paper "Toxico-
logic studies for the assessment of risk associated with
municipal sludge", cites feeding studies that monitored the
health of animals over long periods of time. Twenty-six of
the 30 studies indicated some detrimental effect on the
animal from the sludge.
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"The use of mutagenicity data for assessing municipal
sludge" was explained by Michael J. Plewa of the University
of Illinois. His paper addressed one of the concerns
related to the presence of organic chemicals in sludge:
that a mutagenic or genotoxic agent, which can alter genetic
material or its proper functioning, will be released into
the environment.
The mutagenic properties of five municipal sludges
generated within Illinois were tested using several organisms.
The data indicate that sludges exhibit a wide range of
mutagenic potencies and that there is an apparent correlation
between the mutagenicity of a sludge sample and the relative
industrialization of the municipality. Plewa also noted
that treatment processes may affect mutagenicity, but that
information on this is still lacking. Other research areas
that also need to be investigated to improve risk assessments
are the incorporation of mutagens into the food chain and
their effect on mammals, including humans.
M. Wilson Tabor presented a third line of research in
"Approaches to the fractionation and identification of
mutagens in municipal sludge". According to Dr. Tabor,
chemical characterization of mutagens is necessary to assess
the importance of these compounds as potential human health
hazards and to develop methods to reduce their concentrations
in wastewater and sludge.
Tabor and his colleagues extract residue organics from
a sludge sample, then identify the compounds by fractionation
using a coupled bioassay/chemica1 procedure. This work will
assist in the definition of waste management procedures.
Sydney Munger of the Municipality of Metropolitan
Seattle (Metro) performed an assessment of human health risk
from the organic constituents of land-applied sludge. Using
the known levels of representative organic priority pollutants
in Metro sludge, she calculated the risk of reusing sludge
in silviculture, agriculture, and land reclamation projects.
In "Health effects of organic priority pollutants in
wastewater sludge — a risk assessment", Ms. Munger presented
the exercise for total PCBs and a PAH. She predicted that
levels of these compounds would be increased in soil, food,
and animals, but that any increased risk would be minimal
and controllable through proper site management.
3-3
-------
STATUS REPORT ON TOXIC ORGANICS
OF CONCERN IN SEWAGE SLUDGE
by: Charles S. Spooner
Acting Director, Sludge Task Force
U.S. Environmental Protection
Agency (WH-556)
401 M Street, S.W.
Washington, D.C. 20460
This report presents an overview of our progress
to date on documenting the importance of toxic organic
compounds in sewage sludge.
The report commissioned by the Sludge Task Force,
"Contaminants of Concern", identified 97 persistent organic
compounds which are of potential concern in municipal sewage
sludge. It was agreed that these would be examined further
in a background report similar to reports we have prepared
for cadmium and pathogens, but it was recognized that the
report would be limited by incomplete information on many,
if not most, of these compounds.
The first step was to determine which of the compounds
were sufficiently characterized to be addressed in the
analysis. The six properties thought necessary for this
characterization were:
1. Carcinogenicity 4. Mobility
2. Acute toxicity 5. Concentration
3. Persistence 6. Frequency of occurrence
The 20 toxic organic compounds for which data were
available in all six categories were classified as "Class A"
compounds. An additional 23 compounds for which data were
available in five categories were classified as "Class B".
It was decided to limit the assessment to these two classes.
Two systems of ranking compounds within each class were
tested. These involved assigning index values (from one to
four) to the data used to characterize each compound. These
index values were then composited using different averaging
systems to weight the levels of importance of each attribute,
It was found that, in most cases, these rankings were
insensitive to the averaging system used and the further
3-4
-------
analysis of their relative importance was suspended. Table
1 shows how the compounds in the two classes were ranked
to give an idea of those for which we found sufficient
information to include them in the analysis.
We then examined these traits in pairs, charting
them as shown in Figures 1 through 5 to expose important
combinations of traits.
3-5
-------
TABLE 1
RANKING TOXIC ORGANIC COMPOUNDS
FOUND IN SEWAGE SLUDGE
CLASS A
CLASS B
Benzo(a)pyrene
Vinyl chloride
Acryloni tr ile
1,2-Dichloroethane
Phenol
Tetrachloroethylene
1,1-Dichloroethylene
Carbon tetrachloride
Hexachlorobenzene
Benzene
Chloroform
DDT
2,4,6-Trichlorophenol
Hexachlorobutadiene
Naphthalene
p-Dichloromethane
Dichloromethane
1,1,2,2-Tetrachloroe thane
1,1,2-Trichloroethane
1,1,1-Trichloroethane
Heptachlor
Toxaphene
Dieldr in
Benz(a)anthracene
Chlordane
Lindane
Aldr in
Dibenzo(a,h)anthracene
Tr ichloroethylene
DDE
MethyIchloride
Pentachloropheno 1
1,2,4-Trichlorobenzene
Bromodichloromethane
Tr ichlorofluoromethane
Toluene
Benzylbutyl ester phthalic acid
Bromoform
Dimethylesterphthalic acid
Ethylbenzene
Diethylester phthalic acid
o-Dichlorobenzene
1,3-Dichlorobenzene
3-6
-------
IRE
DESPITE THEIR BENIGN BEHAVIOR, A NUMBER OF ALIPHATICS ARE HIGHLY TOXIC, CARCINOGENIC, OR BOTH
ALPIPHATIC COMPOUNDS
High
TOXICITY
(LD50)
Moderately"
High
U>
Moderately"
Low
Increasi ng
Risk
Low
«F$-Chloroe thane
^•Di-n-butylphthalate
HIV
Dichlorodi f1uoromethane
Methyl bromide
1,3-Dlchloropropylene
Dlchlorobrotnomethane
I ,2-Dtchloropropane
Dlbromochloromethane
Acrylamide
DlethyIphthalate
t, I-Dlchloroethene
I,2-Dichloroethylene
Tetrachloethylene*
Trlchlorofloromethane
Methyl chloride
Broooform
Dimethylphthalate
HI
I 1 ,1 ,2-Trlchloroethane2
A ~\ 1,1 ,2,2-Tetrachloroethane?
IMethy lenechlorlde^
1,1,1-Trlchloroethane?
Butylbenzyl Phthalate?
c/
Bls-2-ethylhe>yl
phthalate2
Hexachlorobutadlene'
— Vinyl Chloride2
I
I,2-Dlchloroethane2
.Chloroform1
-Trtchloroethylene'
•I,1-Dlchloroethylene
.Carbon Tetrachloride'
.1
Not Reported Animal Animal Human Human
as Carcinogenic Suspected Known Suspected Known
CARCINOGENICITY
KEY TO FREQUENCY OF
CONCENTRATION IN
SLUDGE:
o
o
o
o
High Frequency,
High Concentration
High Frequency,
Medium to Low
Concentration
or Vice Versa
Moderate and High/Low
Combi nations
Low Frequency,
Medium to Low
Concentration
or Vice Versa
Increasing Risk
^ Low Frequency,
{-) Low Concentration
A Incomplete Frequency/
Concentration Data
SHADED AREA INDICATES EPA
PRIORITY POLLUTANT
CARCINOGENICITY:
1. EPA-CAG
2. NIOSH
3. MITRE
-------
FIGURE 2.
MOST ALIPHATIC COMPOUNDS WERE FOUND TO BE LOW IN MOBILITY AND PERSISTENCE. AS WITH AROMATICS,
LACK OF DATA PRECLUDES ANALYSIS OF THE BEHAVIOR OF i\ LARGE PROPORTION OF ALIPHATICS. . .
ALIPHATIC COMPOUNDS
(^) Carbon Tetrachloride
High
Bromoform^
PERSISTENCE
BIV
BI
(HALF-LIFE)
Moderately-
High
-dichloroethane
u>
I
oo
Moderately
Low
Increasing
Risk
Low
Methylenechlorlde
I ,2-D1chloroethane
Hexachlorobutadlene
01 -n-butylphthalate
Dlfthylphthalate
1 ,1 J-trichloroethane
\,I-rtlchlorocthylene
Dlchl orubrumoine thane
Dlmethylphthaldte
letrachloroethyIene
BII
Methylchloride
KEY TO FREQUENCY OF
CONCENTRATION IN
SLUDGE:
A Acrylamide
Trichlorofluromethane
Low \ Moderately
Low
\
\
Moderately
\ Hi qh
\
High
Increasing Risk
Bill
MOBILITY IN SOIL
(WATER SOLUBILITY)
Chloroform
I
,1,2-trichloroethane
Vlnylchloride
5)—' ¦' i^.Z-tetrdchloroethane
o
o
o
o
O
A
High Frequency,
High Concentration
High Frequency,
Medium to Low
Concentrati on
or Vice Versa
Moderate and High/Low
Combi nations
Low Frequency,
Medium to Low
Concentration
or Vice Versa
Low Frequency,
Low Concentration
Incomplete Frequency/
Concentration Data
SHADED AREA INDICATES EPA
PRIORITY POLLUTANT
,dei
-------
FIGURE 3.
ALL OF THE INSECTICIDES EXAMINED WERE FOUND TO BE HIGHLY PERSISTENT BUT IMMOBILE. ALL BUT
ONE LACKED SUFFICIENT SLUDGE CONCENTRATION/FREQUENCY DATA, AND AN ADDITIONAL FOUR COMPOUNDS
COULD NOT BE PLOTTED AT ALL . . .
INSECTICIDES
High
PERSISTENCE
(HALF-LIFE)
Moderately"
High
U>
I
Moderately"
Low
Increasing
Risk
Low
¦*— DDT
iDieldrin
Chlordane
Heptachlor BIV
Toxaphene
Endrin
Aldrin
Lindane
DDE
B1
Bill
BII
KEY TO FREQUENCY OF
CONCENTRATION IN
SLUDGE:
Low
Moderately
Low
Moderately
High
High
Increasing Risk
-p—
MOBILITY IN SOIL
(WATER SOLUBILITY)
o
o
o
o
O
High Frequency,
High Concentration
High Frequency,
Medium to Low
Concentration
or Vice Versa
Moderate and High/Low
Combinations
Low Frequency,
Medium to Low
Concentration
or Vice Versa
Low Frequency,
Low Concentration
Incomplete Frequency/
Concentration Data
SHADED AREA INDICATES EPA
PRIORITY POLLUTANT
-------
FIGURE 4.
HALF OF THE AROMATIC COMPOUNDS EXAMINED WERE HIGHLY MOBILE OR PERSISTENT, BUT NOT BOTH.
A LARGE PROPORTION OF AROMATIC COMPOUNDS PREVIOUSLY IDENTIFIED IN SLUDGE LACKED SUFFICIENT
DATA FOR ANALYSIS . . .
AROMATIC COMPOUNDS
u>
I
High
PERSISTENCE
(HALF-LIFE)
Increasing
Risk
Moderately"
High
Moderately"
Low
Low
1,2,4-trlchloroberuene
P
/ Pentachlorophenol
i-Hexachlorobenzene
-Benzo(a Jpyrene
[ BIV
Acenaphthylene
r Naphthalene
(f%\
BI
rl,4-Dichlorobenzene
©
8111
— Ethyl benzene
vj^Kl,3-Dichlorobenzene
Woluene^-7^
2,4,6-Trichlorophenol-
BII
Phenol
W3^-Acrylonitri le
Low
Moderately
Low
Moderately High
High
Increasing Risk
MOBILITY IN SOIL
(WATER SOLUBILITY)
KEY TO FREQUENCY OF
CONCENTRATION IN
SLUDGE:
o
o
o
o
o
A
High Frequency,
High Concentration
High Frequency,
Medium to Low
Concentration
or Vice Versa
Moderate and High/Low
Combi nations
Low Frequency,
Medium to Low
Concentration
or Vice Versa
Low Frequency,
Low Concentration
Incomplete Frequency/
Concentration Data
SHADED AREA INDICATES EPA
PRIORITY POLLUTANT
-------
FIGURE 5.
MOST OF THE INSECTICIDES EXAMINED WERE FOUND TO BE HIGHLY TOXIC AND CARCINOGENIC. DATA WERE
AVAILABLE TO PLOT ALL OF THE INSECTICIDES OF INTEREST, ALTHOUGH SLUDGE CONCENTRATION/FREQUENCY
DATA WERE DEFICIENT . . .
INSECTICIDES
U>
I
High
TOXICITY
(LD50).
Moderately"
High
Moderately"
Low
Increasing
Risk
Low
^ Endrin?
HIV
A Dioxin1
HI
A Dieldrinl
A .Toxaphenel»2
AA Keponel»2
A Heptachlor*
AAldrin1
A Lindane*
A
HI 11
A Chlordanel
DDE2
Mi rex2.3^ HI I
ddd2A Addt1
Not Reported
Animal Animal Human
Human
as Carcinogenic Suspected Known Suspected Known
CARCINOGENICITY
KEY TO FREQUENCY OF
CONCENTRATION IN
SLUDGE:
o
o
o
Increasing Risk
O
o
A
High Frequency,
High Concentration
High Frequency,
Medium to Low
Concentration
or Vice Versa
Moderate and High/Low
Combinations
Low Frequency,
Medium to Low
Concentration
or Vice Versa
Low Frequency,
Low Concentration
incomplete Frequency/
Concentration Data
SHADED AREA INDICATES EPA
PRIORITY POLLUTANT
CARCINOGENICITY:
1. EPA-CAG
2. NIOSH
3. Mitre
-------
TYPES AND CONCENTRATIONS OF ORGANICS
IN MUNICIPAL SLUDGE
by: Lee W. Jacobs
Department of Crop and Soil Sciences
and
Matthew J. Zabik
Pesticide Research Center and
Department of Entomology
Michigan State University
East Lansing, Michigan 48824
ABSTRACT
Sewage sludges from 204 municipal sewage treatment
plants in Michigan were analyzed for 73 organic chemicals
to determine their prevalence and concentrations. Among
the organics tested, 20 compounds were not detected in any
of the sludge samples. The other 53 organics were found in
<1 percent to 95 percent of the sludges analyzed, depending
on the particular compound. Generally, those organic
chemicals which were the most prevalent in the sludges
tested were present at low concentrations. Only four
chemicals were present in 50 percent or more of the sludges
analyzed and at concentrations >10 parts per million (ppm)
-- naphthalene, butylbenzylphthalate, diethylphthalate, and
bis(2-ethylhexy1)phthalate. While the data indicated that
sludges can be highly contaminated with organic chemicals,
the data also suggest that the presence of organic chemicals
in sewage sludges is a manageable aspect of land application
programs. Municipalities should know their dischargers and
conduct limited sludge analyses for those organics that
could be present due to discharges. In this way, concen-
trations of organics, which may be high enough to be a
potential threat to crop production or environmental
quality, can be identified before sludge application to
land.
INTRODUCTION
The potential hazards of sludge application on crop
land include:
(1) Mineralization of excess nitrogen (N) additions
and transport of nitrate-N into groundwater.
3-12
-------
(2) Loss of nutrients and/or metals to surface
waters by run-off from and erosion of sludge-
treated soils.
(3) Contamination of soils or waters by pathogenic
organisms.
(4) Contamination of soils by hazardous organic
chemicals which may be transported to surface
and/or groundwater.
(5) Accumulation of toxic priority pollutants
(metals and organics) in soils, causing photo-
toxicity or plant uptake and transfer of
pollutants into the food chain.
Of the items listed, the fate of hazardous organic chemicals
in soils treated with sludge appears to be the least under-
stood with respect to both long- and short-term problems.
In order to determine the prevalence and levels of
organic chemicals in Michigan sewage sludges, the concentra-
tions of selected organics were measured in sludges collected
from municipal sewage treatment plants in Michigan. Methodology
used for the collection and organic analyses of sewage sludges
has been described by Jacobs and Zabik (1983). Data from
this survey have been used to assess the potential hazards of
sludge-borne organic chemicals when sewage sludges are
applied to agricultural land.
RESULTS
The analysis results for 73 organic chemicals are given
in Table 1. The total number of samples analyzed for each
chemical is shown, along with the number of those samples
that had concentrations above the detection limit for each
chemical. Therefore, one should note that the range, mean, and
median concentrations given pertain only to the samples with
detectable levels.
Using "
group), Tabl
(or 33 perce
limit. Cone
0.0437 parts
(mean) level
means that 3
ppm and 3 9 s
For survey d
biphenyl" as an example (Aromatic Hydrocarbons
e 1 shows that only 78 samples out of 236 tested
nt) had concentrations above the detection
entrations among the 78 samples ranged from
per million (ppm) to 1,730 ppm with an average
of 89.6 ppm. The median value of 8.61 ppm
9 samples had concentrations higher than 8.61
amples had concentrations lower than 8.61 ppm.
ata like these, the "median" level is more
3-13
-------
TARLE 1
CONCENTRATIONS OF SELECTED ORGANIC CHEMICALS IN MICHIGAN SEWAGE SLUDGES
NUMBER OF SAMPLES CONCENTRATION FOUND ABOVE DETECTION
LIMITS (mg/kg dry wt)2
Compound
COMPOUND Analyzed Detected^ Range Mean Median
Aromatic Amines
Benz id i ne
3,4-dichloroaniline
3 ,3'-dichlorobenzidine
p-n it roan i1i ne
238
238
238
238
1
0
0
0
12.7
Aromatic Hydrocarbons
B ipheny1
23 6
78
0.0437-1,730
89.6
8. 61
Hexachlorobenzene
237
102
0.188-26,200
468
18.0
Merc aptobenzoth i azole
238
0
Naphthalene
23 6
119
0.0554-6,610
306
30.3
PBB (polybrominated biphenyl)
210
0
PCR Arochlor 1254
107
42
0.0667-1,960
58.1
5.35
PCR Arochlor 1260
111
65
0.0468-433
19.6
4. 18
1,2,3,4-tetrachlorobenzene
238
0
1,2,3,5-tetrachlorobenzene
238
0
1,2,4,5-tetrachlorobenzene
238
0
Chlorinated Pesticides
A1 d r i n
223
0
Dieldr in
221
63
0.000377-64.7
5.61
1.06
Endr in
223
0
p , p'-HDD
221
10 6
0.00114-84.1
2.54
0.363
p,p1-DDE
219
20 2
0.00118-564
15 . 2
1. 14
p , p 1 -DDT
219
20 9
5 . 9 8{10-5)_135
3. 99
0. 211
L i nda ne
221
37
0 .0005 90-12 .5
0.528
0.0746
Methoxychlor
223
0
2,4-D
223
55
0.000554-7.34
0.633
0.122
-------
TABLE 1 (CONT.)
NUMBER OF SAMPLES
Compound
COMPOUND Analyzed Detected!
Nitrobenzenes
1 chloro-2,4-dinitrobenzene 238 0
1 chloro-2,6-dinitrobenzene 238 0
1 chloro-3,4-dinitrobenzene 238 0
1 chloro-2-nitrobenzene 238 0
1 chloro-4-nitrobenzene 238 0
2,4-dinitrotoluene 238 0
2,6-dinitrotoluene 238 0
Nitrobenzene 238 0
Pentachloronittobenzene 238 0
Phenols
o-chlorophenol 231 20
m-chlorophenol 231 16
p-chlorophenol 231 20
o-cresol 231 15
2,4-dichlorophenol 230 17
2 ,4-dimethylphenol 231 41
4,6-dintro-o-cresol 228 20
2,4-dinitrophenol 228 68
Hydroquinone 229 61
Pentachlorophenol 223 155
Phenol 229 179
2 , 4 ,6-trichlorophenol 223 66
CONCENTRATION FOUND ABOVE DETECTION
LIMITS (mg/kg dry wt)2
Median
Range
Mean
.0766-90.0
13
0.123-93.3
9
.0277-90.0
16
0. 177-183
24
0.209-203
25
.0899-86.7
6
0.202-187
12
0.153-500
23
0. 138-223
8
0. 172-8,490
81
.0166-288
9
0 .195-1 ,330
42
3.60
0.891
3. 28
2.05
4.76
2.19
2.34
4.62
2.55
5.00
2.00
4.81
1
22
9
7
2
52
7
6
23
1
17
3
-------
TABLE 1 (CONT.)
NUMBER OF SAMPLES CONCENTRATION FOUND ABOVE DETECTION
LIMITS (mg/kg dry wt)^
Compound
COMPOUND Analyzed Detected-'- Range Mean Median
Phthalates
Butylbenzylphthalate
234
141
0.0469-12,800
552
59. 1
Diethylphthaiate
234
147
0.0987-3,780
220
50.0
Dimethylphthaiate
236
55
0.106-941
74.6
11.7
Di-n-butylphthalate
237
106
0.0776-3,210
10 4
17.3
Di-n-octylphthalate
237
96
0.0222-2,610
60.7
4.87
Bis(2-ethylhexyl)phthalate
234
197
0.415-58,300
1,250
168
Triaryl
Phosphate
Esters
Cresyldiphenyl phosphate
238
8
0.607-179
46.0
18.9
Tricresyl phosphate
235
162
0.0690-1,650
39.9
6.85
Trixylyl phosphate
236
161
0.0273-2,420
45.3
7.11
Volatiles
and Semi-
Volatiles
Acrylonitrile
155
95
0.0363-82.3
4.78
1.04
Chlorobenzene
158
9
2.06-846
116
10.2
p-chlorotoluene
158
17
1.13-324
61.0
14.7
1,2-dichlorobenzene
215
101
0.0229-809
14.1
0.645
1,3-di chlorobenzene
215
117
0 .0245-1,650
45.2
1.76
1,4-dichlorobenzene
215
141
0.0402-633
12.0
2.02
1,2-di chloropropane
157
110
0.00243-66.0
1.58
0.464
1,3-di chloropropane
158
42
0 .209-309
17.2
3.08
1,3-dichloropropene
157
125
0.00203-1,230
23.0
3.42
-------
TABLE 1 (CONT.)
NUMBER OF SAMPLES CONCENTRATION FOUND ABOVE DETECTION
LIMITS (mg/kg dry wt)^
Compound
COMPOUND Analyzed Detected-*- Range Mean Median
Volatiles
and Semi-
-Volatiles (cont.)
Ethylbenzene
220
14
1.22-65.5
25.4
19.8
Hexachloro-1,3-butad iene
217
103
9.2 4(10~5)-3.74
0.224
0.0355
Hexachloroethane
216
132
0.000360-61.5
0.214
0.019 9
Pentachloroethane
199
56
0.000250-9.22
0.280
0.0300
Styrene
219
21
1.53-5,850
39 4
26.6
Te trachloroethylene
128
93
9.62(10-6)-0.122
0.00408
0.000520
1,2,3-trichlorobenzene
215
79
0.00278-152
2.38
0.0667
1,2,4-trichlorobenzene
217
123
0.00551-51.2
2.34
0.274
1,3,5-trichlorobenzene
217
71
0.00502-39.7
0.823
0.0632
1,2,3-trichloropropane
141
68
0.00459-19.5
1.07
0.352
1,2,3-trichloropropene
137
66
2.11(10~5)-167
7.94
1.14
^Number of samples, among those analyzed, containing organic compound concentrations
higher than the detection limit.
^mg/kg dry wt = milligrams per kilogram dry weight.
-------
meaningful than the "mean" level, which can be skewed
significantly by unusually high or low values in the
ra nge.
The data show that sewage sludges can be just as highly
contaminated with organic chemicals as with heavy metals.
Fourteen organic chemicals had concentrations which ranged up
to >1,000 ppm, six organics had levels >5,000 ppm, and three
had levels >10,000 ppm. Sludges that contain 58,300 ppm
bis(2-ethylhexyl)phthalate, or 26,200 ppm hexachlorobenzene,
or 12,800 ppm butylbenzylphthalate could have serious effects
on the soil-plant system, depending on the rate of sludge
applic at ion.
The concerns for organic chemical additions to soil
must be kept in perspective, however. Many organics could
not be detected in sewage sludge and among the 73 chemicals
listed in Table 1, no organic was detected in 100 percent
of the sludge samples analyzed. If one looks at the
percentage of samples analyzed that contained detectable
levels of any specific organic, the overall degree of
sludge contamination with organic chemicals appears to be a
manageable problem. For example, Table 2 gives the number
of organics which were detected in 30 percent or more of
the samples compared to the number of organics detected in
up to 90 percent or more of the samples. As Table 2 shows,
30 out of 73 chemicals were found in more than 30 percent
of the samples, while 18 organics were found in 50 percent
or more of the samples, and only two organics were found in
>90 percent of the sludges tested.
In addition to the fact that only 25 percent of the
organic chemicals analyzed (18 of 73) were found in 50
percent or more of the sludges, the median concentrations
for those compounds were generally low. Table 3 gives the
number of organics having median concentrations from non-
detectable levels up to >100 ppm. Sixty-one out of 73
chemicals had median concentrations <10 ppm and only one
compound, bis(2-ethylhexyl)phthalate, had a median concen-
tration >100 ppm (168 ppm). Among the compounds that were
found in 50 percent or more of the sludges analyzed, only
four had median concentrations greater than 10 ppm --
naphthalene, butylbenzylphthalate, diethylphthalate, and
bis(2-ethylhexyl)phthalate. In general, then, most of
the organics that were more prevalent in Michigan's sewage
sludges were at concentrations <10 ppm.
3-18
-------
TABLE 2
NUMBER OF ORGANIC CHEMICALS DETECTED IN 30 PERCENT
TO GREATER THAN 90 PERCENT OF THE SLUDGE SAMPLES ANALYZED
PERCENTAGE OF POSITIVE SAMPLES NUMBER OF ORGANIC CHEMICALS
AMONG THOSE ANALYZED DETECTED AT EACH PERCENTAGE
30%
30
>_
40%
26
50%
18
>_
60%
15
>_
70%
8
>_
80%
4
>_
90%
2
TABLE 3
NUMBER OF ORGANIC CHEMICALS HAVING A MEDIAN CONCENTRATION
FROM NON-DETECTABLE TO GREATER THAN 100 PPM
CONCENTRATION LEVEL OR RANGE NUMBER OF ORGANIC CHEMICALS
(mg/kg) AT EACH CONCENTRATION LEVEL
Non-detectable (ND) 21
ND - <10 40
10 - <100 11
> 100 1
3-19
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DISCUSSION
In order to determine at what concentration an organic
chemical in sewage sludge may potentially be a problem for
safe land application, one can make some comparisons with
pesticide application rates. Most pesticides used today are
organic chemicals. The amounts added to soil-plant systems,
in order to effect some type of biological control, normally
range from 1/4 pound (lb) up to 3 to 4 lbs per acre of active
ingredient. If a sludge contains 100 ppm of an organic
chemical, this is equivalent to 0.2 lb per dry ton of sludge.
If one assumes an agronomic rate for sludge application of 1
to 5 dry tons per acre, than 0.2 to 1.0 lb of an organic
chemical (present in the sludge at a concentration of 100
ppm) could be added to the soil. Therefore, concentrations
of an organic approaching 100 ppm must be viewed as potentially
having an impact on the soil-plant system, depending on the
nature of that organic chemical.
From an agronomic or environmental perspective, the
potential hazards of applying an organic chemical to the
soil-plant system in any significant amount were identified
above in the "Introduction". In general, many organics could
be expected to be "tied-up", or bound, by soil organic matter
and biologically "broken down", or decomposed, by soil
microorganisms. This is certainly true for naturally-occurring
organic compounds and many synthetic organic chemicals.
However, there are always exceptions to such a generalization.
Even though the soil-plant system has a great capacity
to assimilate small quantities of many organic chemicals,
temporary and/or long-term detrimental impacts can potentially
occur, depending on the amount and chemical nature of an
organic compound. Therefore, one can expect a wide range
among organics relative to their persistence, leachability,
phytotoxicity, and toxicity to animals, including humans.
While the persistence or leachability (i.e., water solubility)
of an organic chemical may not be serious at a sludge concen-
tration of 100 ppm, the potential for toxicity to plants or
other biological organisms, although temporary, seems real.
Therefore, care must be taken by municipalities and regulatory
agencies to guard against industrial discharges that might
result in unusually high concentrations of an organic chemical
being present in sewage sludge going to agricultural land.
The 100 ppm concentration was selected and used above
only as a means to help bring organic chemical additions by
sludge application into perspective with other organic
chemicals being added to agricultural soils. No "one" con-
centration level would be appropriate to use as a regula-
tion or guideline for land application due to the differences
3-20
-------
in the chemical nature of organics. Rather it should be used
as a "benchmark" concentration level at which the potential
for having a negative impact on the soil-plant system must be
considered real. Certainly, organic chemical concentrations
of 12,800 or 26,200 or 58,300 ppm as were found in some
Michigan sewage sludges (Table 1) cannot be viewed as accept-
able for land application programs.
Because of the wide array of organics present in our
society today, it is impossible to consider a complete sludge
analysis for total organic chemical content. A more logical
approach to guard against the application of sewage sludges,
highly contaminated with an organic(s), to agricultural soils
is for municipalities to know their dischargers. This will
allow one to identify organics that may be present in sewage
sludges and then to conduct limited sludge analyses to
determine whether those organics are present at levels high
enough to be a potential threat to crop production or environ-
mental quality.
Data presented in this paper suggest that sludges can be
highly contaminated with organic chemicals, the same as being
highly contaminated with some inorganic elements (most notably
heavy metals). Care must therefore be taken to guard against
the application of these sludges to agricultural land.
However, these same data also suggest that organic chemical
concentrations in sewage sludges are a manageable aspect of
land application programs, which should not automatically
eliminate this sludge management alternative as an option for
munic ipalit ies.
REFERENCE
Jacobs, L.W., and M.J. Zabik. 1983. Importance of sludge-borne
organic chemicals for land application programs. Proc.
Sixth Ann. Madison Conf. Applied Research & Practice
Municipal & Industrial Waste, September 14-15, 1983,
Madison, Wisconsin. pp. 418-426.
3-21
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TRANSFER OF SYNTHETIC ORGANICS FROM SLUDGE TO SOIL
by: Lewis M. Nay lor and Raymond Loehr
Department of Agricultural Engineering
Cornell University
Ithaca, New York 14853
Concern is frequently expressed over the fate of potentially
toxic synthetic organics when municipal sewage sludge is
applied to land. Data on the concentration of such organics,
especially the priority pollutants, in sludges have been
scarce due to the extensive and complicated sampling, extraction,
and analytical methods that must be employed and the analytical
costs that are involved. However, data related to such
pollutants are now becoming available and permit a better
understanding of the range of concentrations that do occur in
municipal sludges, and the amounts that could be applied to
the soil when such sludges are landspread. This paper:
(1) Summarizes the range of organic priority pollutants
in these municipal sludges.
(2) Indicates the amount of such chemicals that could
be applied to land under current sludge management
guidelines.
In 1980 the U.S. Environmental Protection Agency (EPA)
published an Interim Report (Feiler 1980) of the occurrence
and fate of the 129 priority pollutants in the wastewater
and sludge from 20 publicly owned treatment works across the
United States. The data presented in this paper are derived
from the EPA report. Secondary treatment was provided by
each sewage treatment plant included in the EPA report. The
plants provided a cross-section of the types of facilities,
and wastewater and sludge characteristics found in a broad
spectrum of communities. While the selected plants included
several small treatment plants with a flow less than 10
millions of gallons per day (MGD), most of the plants served
larger cities.
Sludge was sampled at one or more locations within each
treatment plant. Sludge types were designated as primary
sludge, secondary sludge, heat-treated sludge and decant,
combined sludge, digested sludge (anaerobic and aerobic
digestion), and others.
Because of non-uniformity of sludge processing, this
paper will consider, for the purpose of consistency, only
those samples drawn from sludge streams listed as "combined
sludge" in the EPA report. Combined sludges are of interest
because they consist of a mixture of sludges generated by two
3-22
-------
or more wastewater treatment processes, e.g., primary plus
secondary sludges, and represent the character of the sludges
just prior to stabilization or disposal. Use of data for
combined sludges represents a conservative (high) estimate of
the actual amounts of organic priority pollutants that may be
present in sludge since no losses during sludge stabilization
are assumed. Of the 20 sewage treatment plants included in
the EPA study, analyses were reported for combined sludges
from 13 plants. Of these, one plant treated wastewater by
both the activated sludge process and by the trickling filter
process. Combined sludge at this plant was sampled for each
process and analytical data for both sludges are considered
in this paper. Data for a second plant (No. 2) was not
included due to a questionable data value for ammonia. Thus,
data are summarized here for a total of 13 sludges. These
sludges are from plants numbered 1, 3, 4, 5, 7, 8, 10, 11,
14, 15, 16 (two sources), and 17 in the EPA report.
Concentrations of 24 of the more prevalent or more
concentrated of the organic priority pollutants are listed in
Table 1. These compounds were detected in combined sludges
from 10 or more sewage plants, or had a median concentration
of 200 milligrams per liter (mg/l)(wet weight) or greater.
Sludge application rates (dry solids basis) were projected
from concentrations of nitrogen or cadmium listed for each
sludge in order to provide either a hypothetical 100 kilograms
per hectare (kg/ha) of nitrogen available for crop use or an
application of 0.5 kg/ha cadmium. The lower application rate
became the limiting application rate.
Although the ammonia concentration was listed for each
sludge, no data were available on the organic nitrogen
concentration. Because nitrogen loading is a function of
the sludge content of both ammonia and organic nitrogen, an
organic nitrogen value typical of many sludges (3.5 percent)
was assumed in order to calculate the nitrogen loading for
each sludge and the sludge application rate based on nitrogen
limitations. All of the ammonia nitrogen and 20 percent of
the organic nitrogen in the sludge was considered to be
available for crop use within the year of application.
Sludge application rates (dry solids basis) calculated
for the 13 combined sludges varied from 5 to 13 tons/ha. The
median calculated application rate was 11 tons/ha.
Priority pollutant application rates were projected from
sludge application rates and the reported concentrations of
the organic priority pollutants in the combined sludges.
Table 2 summarizes the results for the 13 sludges used in
this evaluation. It is worth noting that these are potential
3-23
-------
TABLE I
ORGAN IC PRIOBITV POLLUTANTS — TOXICITY U- O
PRSSESC6 IH MWfCIPAt. COMBINED UNDIGESTED SEWAGE SLUfJGKS1
CHEMICAL
ACUTE OKMj
Ui5E (mq/kg)
RAT
TOXICITY
RATING3
MO. Tl»ES
cEiECrrea in
COMBINED
sludge
CQHCEMTHATtCW IH COMPILED SLCIDGEs4
jnq/1, wet mg/itg, dry
m-adi an
tarcie
median
range
4.1 -
273
14.5 -
2i
0,7* -
66 5
1.4 -
ras
bisS 2-etny lftesyi 31,000
chlotoc tiler,e volatile
1,2-trans-0 ichloroetfty len-e volat i le
toluene 5,000
11
2
J1
U
3,806
1.7 S9
7t4
722
157 - 11,257
en - 2,000
43 - 54,993
54 - 26,657
109
19
21
15
tjutylbenzy 1 phtS^lstfc
3,140
3
11
S77
J
-
17,725
15
0.52 -
210
2-chJoronaphthalsne
2,07a
3
1
4Q0
¦tsa
4.1
4+7
hexacti lorobutaa i. t na
9a
2
10
-
675.
4.3
0.52 -
8
p'le'Va^ttirene
"500
¦
12
273
34
-
i, ses
7,4
0, S3 -
i4
carb-orb tetrachloride
2,800
3
I
270
230
4.2
¦t.2
vinyl chloride
500
1
i
250
-
1,292
5.7
3 -
110
dibstnte (aitii anthracene
-—
\
250
is
13
13
1, i, 2-triehlor.ae-th.arie
1, no
3
i
222
3
-
441
3.5
D.D36 -
S.tf
anthracene
13
272
34
-
l.,565
1.6
0.B9 -
44
naphthalene
1,780
1
9
23a
23
-
3, 100
7.5
0.9
70
ethy ibenzene
3,5.00
3
12
2or>zeri&
1 ri00
3
11
16
2
-
401
0.32
0.053 -
11.3
tetrschloroethy ^ewa
s,voa
2
11
14
1
-
l,6Ui
0. 3fl
0.024 -
42
ttichloroethylene
4,92&
3
10
57
2
-
1,927
0.9H
0.046 -
44
JFeiler 1990.
^Lewis and Tatkln I960.
-'Relative toxicity with 4 greatest and 1 least (Gosseiift et al. 1976),
^See tent. Kediar ot values vtiere cfiemical was present at detectable levels.
-------
PRIORITY POLLUTANTS APPLIED TO SOIL —
POTENTIAL APPLICATION RATES AND CONCENTRATION
PROJECTED POTENTIAL CONCENTRATION
APPLICATION RATE1 IN TOP 15 cm SOIL
(kg/ha,dry) (mg/kg)
CHEMICAL
median^
range
median^
range
bis(2-ethylhexyl)phthalate
1.2
0.053
-
2.1
0.6
0 .027
-
1.0
chloroethane
0. 17
0.16
-
0. 17
0.085
0.08
-
0 .085
1,2-trans-dichloroethylene
0.24
0.009
-
8.4
0.12
0 .0045
-
4.2
toluene
0.16
0.018
-
1.3
0. 18
0.009
—
0.65
butylbenzyl phthalate
0.11
0 .0063
—
1.4
0.055
0.0032
—
0.7
2-chloronaphthalene
0.03
0.03
0.015
0.015
hexachlorobutad iene
0.03
0 .0063
-
0.054
0.015
0.0032
-
0.027
phenanthrene
0.05
0.009
—
0.53
0.0 25
0.0045
—
0.27
carbon tetrachloride
0.041
0.041
0.0 20
0.0 20
vinyl chloride
0.064
0.02
-
1.3
0.032
0.01
-
0.65
dibenzo (a,h) anthracene
0.16
0.16
0.08
0.08
1,1,2-trichloroethane
0.034
0 .0002
-
0.0 68
0.017
0.0001
—
0.034
anthracene
0.050
0.009
_
0.53
0 .0 25
0.0045
—
0. 27
naphthalene
0.070
0.01
-
0.59
0.035
0.005
-
0. 295
ethylbenzene
0.063
0.013
-
0.38
0.032
0.0065
-
0.19
d i-n-bu tylphthalate
0.047
0.003
-
0. 21
0.024
0.0015
—
0.10
phenol
0.032
0.0011
—
1.5
0.016
0.0055
—
0.75
methylene chloride
0.022
0 .0004
-
0.97
0.011
0.0002
-
0.48
pyrene
0.024
0.004
-
0.22
0.012
0.002
-
0.11
chrysene
0.022
0 .0024
—
0.16
0.011
0.0012
—
0.08
fluora nthene
0.016
0 .00 24
_
0.05
0 .0075
0.002
_
0.0 25
benzene
0.0027
0.0007
-
0.13
0 .0014
0.0004
-
0.0 65
tetrachloroethylene
0.0035
0.0002
-
0.54
0.0018
0.0001
-
0.27
trichloroethylene
0.0125
0.00036
—
0.52
0.006
0.00018
—
0.26
At sludge application rates calculated for individual sludges.
o
Median of values where chemical was present at detectable levels.
-------
application rates. The calculations assume that all of the
chemical is transferred to the soil. This assumption is
conservative because some loss of volatile chemicals is
possible and no losses are assumed during sludge stabilization
processes generally practiced prior to land application.
The sludge was considered to be uniformly injected or
plowed into the soil and the sludge constituents were considered
to be completely mixed into the top 15 centimeters (cm) of
the soil taken to be 2 x 106 kg/ha. No losses of the
chemicals are assumed. The resulting potential concentrations
of the priority pollutants in soil are listed in Table 2.
Even for the most concentrated organic priority pollutants,
application rates listed in Table 2 are not greater than, and
are typically one or two orders of magnitude less than,
recommended application rates for agricultural pesticides
(0.2 to 2.0 kg/ha). For example, the median application rate
of bis(2-ethylhexyl)phthalate is about 1.0 kg/ha when the
sludge is applied at the limiting nitrogen or cadmium rates.
While the application rate for this chemical is similar to
that recommended for pesticides, its toxicity is much lower.
The other priority pollutants listed in Table 1 having
similar toxicities to common pesticides would be applied to
soil at median rates of 0.24 to 0.0046 kg/ha or less.
Polycyclic aromatic hydrocarbons (PAHs) were present
in nearly all of the sludges evaluated. Median concentra-
tions of PAHs in the sludges were 7.6 mg/kg or lower. If
these sludges were applied to soil, at the limiting nitrogen
or cadmium application rates, the PAH concentration in the
soil was calculated to increase by about 0.03 mg/kg or less
for the individual compounds. PAHs are known to be present
in soil as a result of natural causes such as fires and
degradation of plant materials over time (Overcash and Pal
1979). Soil has been found to contain natural PAH concentra-
tions of 0.05 to 0.14 mg/kg (Borneff et al. 1973, Wagner and
Siddiqi 1971). Manure can contain 0.15 to 1.21 mg/kg of
PAHs (Borneff et al. 1973).
A diet scenario was developed to consider health hazards
due to intake of organic priority pollutants through direct
ingestion of sludge, or contaminated soil or crops. This
scenario was based on intake of amounts of a chemical equal
to its acceptable daily dose (E>p) (Dacre et al. 1980 ). For
example, what amounts of the organics might be present on
such crops as leaf lettuce that are commonly consumed raw,
that have a relatively large surface area in proportion to
weight, and that could retain sludge particles or contaminants?
3-26
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If sludge were applied to a garden at nitrogen fertilizer
rates just prior to harvesting, lettuce leaves could retain a
substantial amount of sludge. For example, if a leaf having
an area of 0.0075 square meters (m2) were to retain an
amount of sludge equivalent to the maximum application rate
(1.3 kg/it»2) f each leaf under extraordinary circumstances
might retain as much as 0.01 kg or 10 g of dry sludge (about
2 to 3 teaspoonsful) or about 5 to 10 times the weight of the
leaf. The quantity of hexachlorobutadiene (HCBD), the most
toxic of the chemicals listed, in this quantity of sludge
could be as great as 0.08 mg at the maximum concentration
reported (Table 1). The acceptable daily dose (DT) of
HCBD can be shown to be 0.063 mg. Thus, only one leaf of
lettuce completely coated with sludge could be consumed
daily and be within the safe DT level (Table 3).
TABLE 3
POTENTIAL INTAKE HEXACHLOROBUTADIENE FROM A
SLUDGE-CONTAMINATED CROP (LETTUCE LEAVES)
SLUDGE
APPLICATION
CROP
WASHED
SLUDGE
OR SOIL
RETAINED
ON LEAF
HCBDl RE-
TAINED ON
LEAF (mg)
NO. OF
LEAVES
RETAINING
Dt DOSE2
Just prior
to harvest3
No
10 g sludge
8 x 10"2
1
Fall
application3,4
No
10 g soil
3 x 10-4
200
Fall
application3,4
Yes
0.005 g soil
1 x 10-7
>500,000
IhCBD = hexachlorobutadiene.
2dt = acceptable daily dose (Dacre et al. 1980).
For HCBD, D^. = 0.063 mg.
^Sludge application rate = 13 dry ton/ha.
^Sludge incorporated to a depth of 15 cm. No losses
of HCBD are assumed.
It is unrealistic, however, to expect that an individual
would apply sludge just prior to harvest and knowingly
consume lettuce coated with sludge. During rainfall or
irrigation, sludge-amended soil could splash onto the leaves
of the crop. Such soil might contain up to 0.027 mg/kg of
hexachlorobutadiene as shown in Table 2. If such soil were
3-27
-------
to splash onto the leaves of the crop and be retained in the
amount of 10 g (0.01 kg) per leaf, the amount of hexachloro-
butadiene present would be 0.0003 mg. About 200 such lettuce
leaves (Table 3) would have to be eaten daily to consume an
amount of this chemical equivalent to its Dp. Washing raw
vegetable crops prior to eating would remove nearly all
visible particles of soil and hence sludge that is adhering
to the crops. Residual soil on such a lettuce leaf might be
equivalent to a particle 2 millimeters in diameter. Such a
particle may weigh about 5 mg (5 x 10~6 kg) and could
contain about 1 x 10~7 mg Qf hexachlorobutadiene. Over
500,000 such leaves (>200 kg) would need to be consumed
before the acceptable daily dose would be reached (Table 3).
This scenario indicates that, except possibly where
sludge is consumed directly in large amounts, consumption of
contaminated crops will not normally result in the ingestion
of amounts of organic priority pollutants exceeding the
acceptable daily dose.
REFERENCES
Rorneff, J.G., H.G. Farksadi, H. Glathe, and H. Kunte.
1973 . The fate of polycyclic aromatic hydrocarbons in
experiments using sewage sludge-garbage composts as
fertilizers. Zbl. Bakt. Hyg. , IB, 157: 151-164.
Dacre, J.C., D.H. Rosenblatt, and D.R. Cogley. 1980.
Preliminary pollutant limit values for human health
effects. Environ. Sci. Tech. 14:778-784.
Feiler, H. 1980. Fate of Priority Pollutants in Publicly
Owned Treatment Works — Interim Report. EPA-440/1-80-301 .
U.S. Environmental Protection Agency, Washington,
D.C.
Gosselin, R.E., H.C. Hodge, R.P. Smith, and M.N. Gleason.
1976. Clinical Toxicology of Commercial Products.
Williams and Wilkins Co., Baltimore, Maryland.
Lewis, R.J., and R.L. Tatkin (eds.). 1980. Registry of
Toxic Effects of Chemical Substances. 1979 Edition.
U.S. Department of Health and Human Services, Washington,
D.C.
Naylor, L.M., and R.C. Loehr. 1982. Priority pollutants in
municipal sewage sludge. Biocycle 23 (Jul-Aug 1982):
18-22.
3-28
-------
Naylor, L.M., and R.C. Loehr. 1982. Priority pollutants in
municipal sewage sludge -- II. Biocycle 23(Nov-Dec
1982) s37-41.
Overcash, M.R., and D. Pal. 1979. Design of Land Treatment
Systems for Industrial Wastes -- Theory and Practice.
Ann Arbor Science Publishers, Inc., Ann Arbor, Michigan.
Wagner, K.H., and I. Siddiqi. 1971. The metabolism of
3,4-benzopyrene and benzo(e)acephenanthrylene in summer
wheat. Z. Pflanzenern, Bodenkd. 127:211-218.
3-29
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STABILITY, MOBILITY, AND BIOACTIVITY
OF ORGANICS IN SOIL
by: Jerry B. Weber and Harry J. Strek
Crop Science Department
and
Michael R. Overcash
Chemical Engineering Department
North Carolina State University
Raleigh, North Carolina 27650
INTRODUCTION
The behavior of organic chemicals in the terrestrial
system has been developed through numerous agricultural and
environmental research programs over about 80 years. Adapta-
tion of this information to municipal sludge land treatment
requires specification of the inputs to the system as well as
a thorough understanding of the behavioral pathways occurring
with organics in a terrestrial system. This paper focuses on
the latter subject as an introduction and interpretation of
the broad field of land application. The pathways covered
are stability, adsorption and binding, mobility, and biological
activity, which is related to microbial and plant processes.
Much of the material referenced evolved from a substantive
research grant on the behavior of organic priority pollutants
in municipal sludge land treatment systems. The grant is
from the U.S. Environmental Protection Agency Municipal
Environmental Research Laboratory (MERL), Cincinnati (Dr. J.
Ryan, Project Officer). Detailed results and conclusions
will be a part of that final report (expected 1984) and are
not repeated in this paper.
STABILITY
The stability or longevity of an organic chemical in
soil or water is dependent upon the:
(1) Molecular structure of the chemical (Hill 1978,
Weber 1966 ) .
(2) Chemical properties of the chemical and soil
(Hartley and Graham-Bryce 1980, Weber 1972).
(3) Accessibility to degradation processes (Kearney and
Kaufman 1976, Weber and Coble 1968, Weber and Scott
1966, Weber et al. 1969).
3-30
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Organic chemicals such as simple aliphatic acids (e.g.,
acetic acid) and aromatic acids (e.g., benzoic acid) are
readily degraded by soil microorganisms (Hill 1978); chemicals
such as the phenols (e.g., 2,4-dinitrophenol) are intermediate
in susceptibility to degradation (Shea et al. 1983); while
those such as the highly chlorinated hydrocarbons (e.g.,
polychlorinated biphenyls) are very resistant to degradation
(Strek and Weber 1982) primarily because the molecular
configurations of the chemicals affect the ability of
microorganisms to attack the structures. Cationic organic
chemicals such as the herbicides diquat and paraquat may be
biologically available and hence degradeable if bound to
organic soil colloids or to nonexpanding clays such as
kaolinite, but the compounds are very nondegradeable if
bound on the internal surfaces of expanding clays such as
montmorillonite (Weber and Coble 1968, Weber and Scott 1966,
Weber et al. 1969). Because the organic cations are
trapped in an inaccessible position between the silicate
sheets of the clay crystals, microorganisms cannot reach
them, resulting in lack of degradation (Philen et al. 1971,
Weber et al. 1965, Weed and Weber 1968).
INACTIVATION THROUGH BINDING
Binding of organic chemicals to soil particulate matter
or to lake sediments is dependent upon the:
(1) Type of soil constituent present.
(2) Properties of the organic chemical.
(3) Edaphic factors such as pH and nutrient levels.
(4) Climatic factors such as temperature and moisture
content (Weber 1972, 1976a and b, 1978, Weber et
al. 1969a and b).
Clay minerals in soils strongly adsorb not only cationic
organic chemicals but also protonated species of basic
organic chemicals, and they weakly adsorb polar nonionic
chemicals; they do not adsorb nonpolar, nonionic chemicals
or anionic organic chemicals to any extent (Grimm 1968,
Weber 1972). Hydrous oxides in soils readily adsorb anionic
organic chemicals and, to a much lesser extent, nonionic
organic chemicals, but this is also strongly pH dependent
(Bear 1965). Organic soil colloids such as humic acids
readily adsorb cationic organic chemicals, basic organic
chemicals, and both polar and nonpolar nonionic organic
chemicals (Kononova 1966, Schnitzer and Khan 1978, Weber
1972, Weber et al. 1969a and b, Weed and Weber 1974).
3-31
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Binding of cationic compounds depends on the valence
charge, with stronger binding at higher valence, while that
of basic molecules depends on the strength of the ionization
constant. Binding of nonionic organic chemicals to soil
colloids is largely dependent on the water solubility and
molecular size of the chemical in question. Adsorption
tends to increase with decreased water solubility and
increased molecular size (Carringer et al. 1975, Weber
1970 ) .
For organic chemicals with basic properties, adsorption
in soils increases with a decrease in pH because the proto-
nated species are preferentially adsorbed by the negatively
charged surfaces (Best et al. 1975, Weber 1966, 1972, 1980).
For organics with acid properties, adsorption in soils
also increases with a decrease in pH because molecular
species adsorb to soil surfaces whereas anionic species are
repelled by the negatively charged surfaces. An exception
to this is the binding of anionic species to positively
charged oxides which are present in high amounts in tropical
soils. These oxides take on positive charge at lower pH
levels and may actually outweigh the total negative charge
in the soil. Solution pH level also affects the water
solubility of ionizable organic chemicals and this in turn
affects binding of the chemicals to soil colloids.
Temperature exerts an effect on the binding of organic
chemicals to soil colloids by two fundamental mechanisms:
(1) temperature affects the energy level at which the
molecules are held to colloidal surfaces (generally adsorp-
tion decreases with increased temperature), and (2) tempera-
ture affects the solubility of the chemical in water (gener-
ally most chemicals are more soluble at higher temperatures
[Weber et al. 1965]). The presence of nutrients in the soil
solution affects organic chemical binding to soil colloids
if the nutrients compete for binding sites (Best et al.
1972, Weber et al. 1968).
MOBILITY
Mobility of organic chemicals in soils occurs through
mass flow in the solution phase for nonvolatile chemicals,
and occurs through diffusion in the air phase along with
diffusion and mass flow in solution phase for volatile
chemicals. The mobility of organic chemicals in soils
behaves in a manner that is generally the inverse of
adsorption by soil colloids. Immobile chemicals are tightly
bound to soil colloids and highly mobile chemicals are only
weakly bound or not bound at all (Weber 1977, Weber and
Whitacre 1982). Chemical mobility is dependent upon the
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same properties that control adsorption to soil particulate
matter. Highly water soluble anionic species are generally
the most mobile, while cationic species or nonionic chemicals
of very low water solubility are the least mobile.
Movement of organic chemicals off of land by way of
runoff or washoff is governed by the same principles which
regulate adsorption and leachability in soils (Weber et al.
1980, Wiese et al. 1980).
BIOAVAILABILITY
Adsorption of organic chemicals by soil colloids and
the amount and type of soil amendments control the rate at
which the chemicals move in soils and the rate at which the
chemicals are utilized by soil organisms (Weber 1974, Weber
and Best 1972). Soil organic matter, soil clay minerals,
exchange resins, and activated carbon have all been shown to
effectively decrease, and in some cases completely inhibit,
the movement and/or utilization of organic chemicals by soil
microorganisms, plants, and fish (Peeper and Weber 1976,
Scott and Weber 1967, Shea and Weber 1980, Shea et al. 1980,
Strek and Weber 1982, Weber 1976a and b, Weber et al. 1969,
Weber et al. 1981).
Decomposition of soil-bound organic chemicals is
generally lower than for free organic chemicals (in the soil
solution proper) and is dependent on the type of adsorption
bond involved, physical accessibility to the chemical, and
the durability of the adsorbent involved. Weakly-bound
organics which are readily accessible to soil organisms may
be nearly as degradeable as they would be in the "free"
form. Strongly-bound and/or inaccessible organics bound to
very durable adsorbents such as clay minerals or charcoal
are likely to be very long-lived in soils. However, their
effects on organisms are severly curtailed by being bound.
The rate of degradeability and/or biological availability of
most organic chemicals falls somewhere between these two
extremes.
REFERENCES
Bear, F.E. 1965. Chemistry of the Soil. Reinhold Publishing
Corp., New York. 515 pp.
Best, J.A., J.B. Weber, and S.B. Weed. 1972. Competitive
adsorption of diquat2+, paraquat2"4", and Ca2+ on
organic matter and exchange resin. Soil Sci. 114:444-450,
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Best, J.A, J.B. Weber, and T.J Monaco. 1975. Influence of
soil pH on s-trizine availability to plants. Weed Sci.
23:378-382.
Carringer, R.D., J.B. Weber, and T.J. Monaco. 1975. Adsorp-
tion-desorption of selected pesticides by organic matter
and montmorillonite. J. Agr. Food Chem. 23:568-572.
Grimm, R.E. 1968. Clay Mineralogy. McGraw-Hill Book Co.,
New York. 596 pp.
Harrison, G.W., J.B. Weber, and J.V. Baird. 1976. Herbicide
phytotoxicity as affected by selected properties of
North Carolina soils. Weed Sci. 24:120-126.
Hartley, G.S., and I.J. Graham-Bryce. 1980. Physical Princi-
pals of Pesticide Behavior. Vol. 1. Academic Press,
New York. 518 pp.
Hill, I.R. 1978. Microbial transformation of pesticides.
In: I.R. Hill and S.J.L. Wright (eds.), Pesticide
Microbiology. Academic Press, New York. pp. 137-183.
Kearney, P.C., and D.D. Kaufman. 1976. Herbicides -- Chemist
Degradation, and Mode of Action. Marcel Dekker, Inc.,
New York. 1036 pp.
Kononova, M.M. 1966. Soil Organic Matter. Pergamon Press,
Inc., Elmsford, New York. 544 pp.
Peeper, T.F., and J.B. Weber. 1976. Activity and persistence
of atrazine, procyazine, and VEL-S026 as influenced by
soil organic matter and clay. Proc. South. Weed Sci.
Soc. 29:387-398.
Philen, O.D., Jr., S.B. Weed, and J.B. Weber. 1971. Surface
charge characterization of layer silicates by competitive
adsorption of two organic divalent cations. Clays and
Clay Minerals 19:295-302.
Schnitzer, M., and S.U. Khan. 1978. Soil Organic Matter.
Elsevier Scientific Publishing Company, New York. 319 pp
Scott, D.C., and J.B. Weber. 1967. Herbicide phytotoxicity
as influenced by adsorption. Soil Sci. 104:151-158.
Shea, P.J., and J.B. Weber. 1980. Effect of pH and soil
constituents on the persistence and availability of
fluridone. Proc. South. Weed Sci. Soc. 33:240-246.
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Shea, P.J., H.J. Strek, and J.B. Weber. 1980. Polychlorinated
biphenyls: absorption and bioaccurnulation by goldfish
(Carassius auratus) and inactivation by activated
carbon. Chemosphere 9:157-164.
Shea, P.J., J.B. Weber, and M.R. Overcash. 1983. Biological
activities of 2,4-dinitrophenol in plant-soil systems.
Res. Rev. 87:1-41.
Strek, H.J., and J.B. Weber. 1982. Adsorption and reduction
in bioactivity of polychlorinated biphenyl (Aroclor
1254) to redroot pigweed by soil organic matter and
montmorillonite clay. Soil Sci. Soc. Amer. J. 46:318-322.
Strek, H.J., and J.B. Weber. 1982. Behavior of polychlorinated
biphenyls (PCBs) in soils and plants. Environ. Pollution
28A:291-312.
Weber, J.B. 1966. Molecular structural and pH effects on
the adsorption of 13 ^-triazine compounds on montmorillonite
clay. Amer. Mineralog. 51:1657-1670.
Weber, J.B. 1970. Adsorption of _s-triazines by montmorillonite
as a function of pH and molecular structure. Soil Sci.
Soc. Amer. Proc. 34:401-404.
Weber, J.B. 1972. Interaction of organic pesticides with
particulate matter in aquatic and soil systems. Adv.
Chem. Series 111:55-120.
Weber, J.B. 1974. Effects of soil on biological activity of
pesticides. I_n: W.D. Guenzi (ed.), Pesticides in Soil
and Water. Soil Science Society of America, Inc.,
Madison, Wisconsin. pp. 223-256.
Weber, J.B. 1976a. Fixed and biologically available soil-
bound pesticides. In: D.D. Kaufman, G.D. Paulson, and
S.K. Bandel (eds.), Bound and Conjugated Pesticide
Residues. Symposium Series No. 29. American Chemical
Society, Washington, D.C. pp. 354-355.
Weber, J.B. 1976b. Geochemistry of sediment/water interactions
of nutrients, pesticides and metals, including observations
on availability. In: Proc. Fluvial Transport of Sediment-
Associated Nutrients and Contaminants. International
Joint Commission, Kitchener, Ontario, Canada. pp. 245-253.
Weber, J.B. 1977. Herbicide mobility in soils. I_n: B.
Truelove (ed.), Research Methods in Weed Science.
Southern Weed Science Society, Auburn Printing, Auburn,
Alabama. pp. 73-78.
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Weber, J.B. 1978. Fate of organics in sludges applied to
the land. I_n: Fifth Nat. Conf. on Acceptable Sludge
Disposal Techniques. Information Transfer, Inc.,
Rockville, Maryland. pp. 117-124.
Weber, J.B. 1980. Adsorption of buthidazole, VEL 3510,
tebuthiuron, and fluridone by organic matter, montmoril-
lonite clay, exchange resins, and a sandy loam soil.
Weed Sci. 28:478-483.
Weber, J.B., and J.A. Best. 1972. Activity and movement of
13 soil-applied herbicides as influenced by soil reaction.
Proc. South. Weed Sci. Soc. 25:403-413.
Weber, J.B., and H.D. Coble. 1968. Microbial decomposition
of diquat adsorbed on montmorillonite and kaolinite
clays. J. Agr. Food Chem. 16:475-478.
Weber, J.B., and D.C. Scott. 1966. Availability of a cationic
herbicide adsorbed on clay minerals to cucumber seedlings.
Science 152:1400-1402.
Weber, J.B., and D.M. Whitacre. 1982. Mobility of herbicides
in soil columns under saturated- and unsaturated-flow
conditions. Weed Sci. 30:579-584.
Weber, J.B., R.C. Meek, and S.B. Weed. 1969a. The effect of
cation-exchange capacity on the retention of diquat^+
and paraquat^ by three-layer type clay minerals: II.
Plant availability of paraquat. Soil Sci. Soc. Amer.
Proc. 33:382-385.
Weber, J.B., P.W. Perry, and R.P. Upchurch. 1965. The
influence of temperature and time on the adsorption of
paraquat, diquat, 2,4-D, and prometone by clays, charcoal,
and an anion-exchange resin. Soil Sci. Soc. Amer. Proc.
29:678-688.
Weber, J.B., P.J. Shea, and H.J. Strek. 1980. An evaluation
of nonpoint sources of pesticide pollution in runoff.
In: M.R. Overcash and J.M. Davidson (eds.), Environmental
Impact of Nonpoint Source Pollution. Ann Arbor Science
Publishers, Inc., Ann Arbor, Michigan. pp. 69-98.
Weber, J.B., H.J. Strek, P.J Shea, and M.R. Overcash. 1981.
Nonpoint source pollution from PCBs: bioavailability
and inactivation with activated carbon. In: M.A.Q.
Khan and R.H. Stanton (eds.), Toxicology of Halogenated
Hydrocarbons. Pergamon Press, Inc., Elmsford, New York,
pp. 364-374.
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Weber, J.B., T.M. Ward, and S.B. Weed. 1968. Adsorption and
desorption of diquat, paraquat, prometone by montmorillonite
and kaolinite clay minerals. Soil Sci. Soc. Amer. Proc.
32:485-487.
Weber, J.B., S.B. Weed, and T.M. Ward. 1969b. Adsorption of
£-triazines by soil organic matter. Weed Sci. 17:417-421.
Weed, S.B., and J.B. Weber. 1968. The effect of adsorbent
charge on the competitive adsorption of divalent organic
cations by layer-silicate minerals. Amer. Mineralog.
53:478-490.
Weed, S.B., and J.B. Weber. 1974. Pesticide-organic matter
interactions. Ijn: W.D. Guenzi (ed.), Pesticides in Soil
and Water. Soil Science Society of America, Inc.,
Madison, Wisconsin. pp. 39-66.
Wiese, A.F., K.E. Savage, J.M. Chandler, L.C. Liu, L.S.
Jeffery, J.B. Weber, and K.S. LaFleur. 1980. Loss of
fluometuron in runoff water. J. Environ. Qual. 9:1-5.
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TOXICOLOGIC STUDIES FOR THE ASSESSMENT OF
RISK ASSOCIATED WITH MUNICIPAL SLUDGE
by: John G. Babish
Department of Preventive Medicine
New York State College of
Veterinary Medicine
Cornell University
Ithaca, New York 14853
Adequate toxicologic studies are a prerequisite for
assessing the adverse health impact of sludge application to
agricultural lands. To date, very few well-designed toxico-
logic studies have been performed that can be used for
human risk assessment. Studies done directly on the sludges
themselves, such as mutagenicity studies, are best used to
characterize the sludge as high or low risk. Only feeding
studies that monitor the health of the animal over a chronic
period are useful for determining toxicologic effects from
sludge treatment of fields.
Of 30 studies on the movement of toxic materials from
sludge to animals, 26 were positive in that some detrimental
effect of sludge was observed. Fourteen of these studies
(Anderson et al. 1982, Chaney et al. 1978b, Damron et al.
1981, Furr et al. 1976, Gutenmann et al. 1982, Hansen and
Hinesley 1979, Helmke et al. 1979, Lisk et al. 1982, Miller
and Boswell 1976, 1979, 1981, Stoewsand et al. in press,
Wade et al. 1982, Williams et al. 1978) looked only at the
heavy metal composition of various tissues. Cadmium was the
heavy metal most frequently reported elevated; kidney and
liver were the organs most frequently found to differ from
controls.
A total of five studies (Babish et al. 1979, Baker et al,
1980, Chaney et al. 1978a, Telford et al. in press c, 1982)
reported enhanced mixed-function oxidase activity in addition
to increased heavy metal content of tissues. This increase
in mixed-function oxidase activity was generally associated
with those P-450 enzymes induced via the Ah-receptor (Aryl-
hydrocarbon receptor). As such, the compounds would be
expected to induce mixed-function oxidase activity in a
variety of tissues and possibly be immunosuppressive.
Two studies found a relationship between sludge and
polychlorinated biphenyl (PCB) content of certain tissues
(Hansen et al. 1981, Haschek et al. 1979). In the study by
Haschek et al. , elevated PCB content of the liver was found
in sheep consuming cabbage grown on 100 percent sludge.
Additionally, animals exhibited proliferation of the smooth
endoplasmic reticulum and various degenerative liver changes.
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An epidemiologic study (Gutenmann et al. 1982) showed that
serum PCB levels were proportional to percent performance of
gardening with sludge-treated home garden plots (p = 0.035)
and a negative association existed with the subjects customar-
ily wearing gloves while gardening (p = 0.021).
Several studies also reported abnormal physiologic and
biochemical responses in animals consuming crops grown on
sludge-amended soil. Sheep fed grass-legume pasture grown
on sludge-treated soil exhibited larger testes and had
higher uric acid in blood (Hogue et al. in press). On a
diet consisting of corn silage grown on sludge-treated land,
sheep showed enlarged mitochondria and hepatocellular
necrosis; additionally, all animals were reluctant to
consume the sludge-grown silage (Heffron et al. 1980).
Goats consuming grass-legume silage from sludge-treated
fields produced far too little milk for their kids (Telford
et al. in press b). Chickens receiving corn grain from
sludge-treated fields showed a decrease in feed efficiency
(Hinesley et al. 1976).
Finally, several studies have traced mutagenic activity
from the sludge to the soil to the animal consuming the crop
grown on the soil. In a study with rats, promutagenic
activity was found in the urine of rats consuming beets
grown on sludge-treated fields (Boyd et al. 1982). Sheep
consuming sugar beets grown on sludge-amended plots had
direct-acting mutagens in their blood and urine (Telford et
al. in press a). An additional finding in this study was a
lower hemoglobin content in the red blood cells of the test
animals.
REFERENCES
Anderson, T.J., J.W. Barette, C.S. Clark, V.J. Elia, and
V.A. Majeti. 1982. Metal concentrations in tissues of
meadow voles from sewage sludge treated fields. J.
Environ. Qual. 11:272-277.
Babish, J.G., G.S. Stoewsand, A.K. Furr, T.F. Parkinson,
C.A. Bache, W.H. Gutenmann, P.C. Wszolek, and D.J. Lisk.
1979. Elemental and polychlorinated biphenyl content
of tissues and intestinal aryl hydrocarbon hydroxylase
activity of guinea pigs fed cabbage grown on municipal
sewage sludge. J. Agr. Food Chem. 27:399-402.
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Baker, E.L., P.L. Landrigan, C.J. Glueck, M.M. Zack, Jr.,
J.A. Liddle, V.W. Burse, W.J. Housworth, and
L.L. Needham. 1980. Metabolic consequences of
exposure of PCBs in sewage sludge. Am. J. Epidera.
112:553-563.
Boyd, J.N., G.S. Stoewsand, J.G. Babish, J.N. Telford, and
D.J. Lisk. 1982. Safety evaluation of vegetables
cultured on municipal sewage sludge-amended soil.
Arch. Environ. Contam. Toxicol. 11:399-405.
Chaney, R.L., G.S. Stoewsand, C.A. Bache, and D.J. Lisk.
1978a. Cadmium deposition and hepatic microsomal
induction in mice fed lettuce grown on municipal
sludge-amended soil. J. Agr. Food Chem. 26:992-994.
Chaney, R.L., G.S. Stoewsand, A.K. Furr, C.A. Bache,
and D.J. Lisk. 1978b. Elemental content of tissues of
guinea pigs fed Swiss chard grown on municipal sewage
sludge-amended soil. J. Agr. Food Chem. 26:994-997.
Damron, B.L., M.F. Hall, D.M. Janky, H.R. Wilson, D. Osuna,
R.L. Suber, and M.C. Lutrick. 1981. Corn fertilized
with municipal sludge in the diet of chicks and hens.
Poultry Sci. 60:1491-1496.
Furr, A.K., G.S. Stoewsand, C.A. Bache, and D.J. Lisk.
1976. Study of guinea pigs fed Swiss chard grown on
municipal sludge-amended soil. Arch. Environ. Health
31:87-91.
Gutenmann, W.H., C.A. Bache, D.J. Lisk, D. Hoffman,
J.D. Adams, and D.C. Elfving. 1982. Cd and Ni in
smoke of cigarettes prepared from tobacco cultured on
municipal sludge-amended soil. J. Tox. Environ. Health
10:423-431.
Hansen, L.G., and T.D. Hinesley. 1979. Cadmium from soil
amended with sewage sludge: effects and residues in
swine. Environ. Health Perspect. 28:51-57.
Hansen, L.G., P.W. Washko, L.G.M.T. Tuinstra, S.B. Dorn, and
T.D. Hinesley. 1981. Polychlorinated biphenyl pesti-
cide and heavy metal residues in swine foraging on
sewage sludge-amended soils. J. Ag. Food Chem.
29:1012-1017.
Haschek, W.M., A.K. Furr, T.F. Parkinson, C.L. Heffron,
J.T. Reid, C.A. Bache, P.C. Wszolek, W.H. Gutenmann,
and D.J. Lisk. 1979. Element and polychlorinated
biphenyl disposition and effects in sheep fed cabbage
grown on municipal sewage sludge. Cornell Vet. 69:302-3
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Heffron, C.L., J.T. Reid, D.C. Elfving, G.S. Stoewsand,
W.M. Haschek, J.N. Telford, A.K. Furr, T.F. Parkinson,
C.A. Bache, W.H. Gutenmann, P.C. Wszolek, and D.J.
Lisk. 1980. Cadmium and zinc in growing sheep fed
silage corn grown on municipal sludge-amended soil. J.
Agr. Food Chem. 28:58-61.
Helmke, P.A., W.P. Robarge, R.L. Corotave, and P.J. Schumberg.
1979. Effects of soil-applied sewage sludge on concen-
tration of elements in earthworms. J. Environ. Quality
8:322-327.
Hinesley, T.D., E.L. Ziegler, and J.J. Tyler. 1976.
Selected chemical elements in tissue of pheasants fed
corn grain from sewage sludge-amended soil. Agro-
Ecosystems 3:11-26.
Hogue, D., J.J. Parish, R.H. Foote, J.R. Stouffer,
J. Anderson, G.S. Stoewsand, J.N. Telford, C.A. Bache,
W. Goodman, and D.J. Lisk. Toxicologic studies with
male sheep grazing on municipal sludge-amended soil.
J. Tox. Environ. Health (in press).
Lisk, D.J., R.D. Boyd, J.N. Telford, J.G. Babish,
G.S. Stoewsand, C.A. Bache, and W.H. Gutenmann. 1982.
Toxicologic studies with swine fed corn grown on
municipal sludge-amended soil. J. Animal Sci.
55:613-619.
Miller, J., and F.C. Boswell. 1976. Mineral composition of
liver and kidney of rats fed corn, sorgum, and soybean
grain grown with sewage sludges and NPK fertilizer. J.
Agr. Food Chem. 24:935-938.
Miller, J., and F.C. Boswell. 1979. Mineral content of
selected tissues and feces of rats fed turnip greens
grown on soil treated with sewage sludge. J. Agr. Food
Chem. 27:1361-1365.
Miller, J., and F.C. Boswell. 1981. Cd, Pb and Zn in growing
rats fed corn leaf tissue grown on soil amended with
sewage sludge or heavy metal salts. Environ. Health
Perspect. 42:197-202.
Stoewsand, G.S., J.N. Telford, J.L. Anderson, C.A. Bache,
and W.H. Gutenmann. Toxicologic studies with Japanese
quail fed winter wheat grown on municipal sludge-
amended soil. Arch. Environ. Contam. Toxicol, (in
press).
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Telford, J.N., J.G. Babish, P.B. Dunham, D.E. Hogue,
K.W. Miller, G.S. Stoewsand, B.H. Magee, J.R. Stouffer,
C.A. Bache, and D.J. Lisk. Toxicologic studies with
lambs fed sugar beets grown on municipal sludge-amended
soil: lowered relative hemoglobin in red blood cells
and mutagens in blood and excreta. Cornell Vet. (in
press a).
Telford, J.N., J.G. Babish, B.E. Johnson, M.L. Thonney,
W.B. Currie, C.A. Bache, W.H. Gutenmann, and D.J. Lisk.
Toxicologic studies with pregnant goats fed grass-legume
silage grown on municipal sludge-amended subsoil.
Arch. Environ. Contam. Toxicol, (in press b).
Telford, J.N., D.E. Hogue, K.W. Miller, G.S. Stoewsand,
J.R. Stouffer, C.A. Bache, B.H. Magee, and D.J. Lisk.
Toxicologic studies with growing sheep fed grass-legume
hay grown on municipal sludge-amended subsoil. J.
Animal. Sci. (in press c).
Telford, J.N., M.L. Thonney, D.E. Hogue, J.R. Stouffer,
C.A. Bache, W.H. Gutenmann, D.J. Lisk, J.G. Babish, and
G.S. Stoewsand. 1982. Toxicologic studies in growing
sheep fed silage corn cultured on municipal sludge-
amended acid subsoil. J. Tox. Environ. Health 10:73-85.
Wade, S.E., C.A. Bache, and D.J. Lisk. Cd accumulation by
earthworms inhabiting municipal sludge-amended soil.
Bull. Environ. Contam. Toxicol. 28:557-560.
Williams, P.H., J.S. Shenk, and D.E. Baker. 1978. Cadmium
accumulation by meadow voles (Microtus pennsylvanicus)
from crops grown on sludge-treated soil. J. Environ.
Qual. 7:450-454.
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THE USE OF MUTAGENICITY DATA FOR
ASSESSING MUNICIPAL SLUDGE
by: Michael J. Plewa and Philip K. Hopke
Institute for Environmental Studies
University of Illinois
Urbana, Illinois 61801
INTRODUCTION
A serious problem facing the United States is the
disposal of the sludge resulting from the treatment of
municipal sewage. There has been a substantial increase
in the number and efficiency of sewage treatment plants in
the past decade, particularly in suburban and rural areas,
resulting in an increased amount of sludge requiring disposal.
Approximately 9.0 x 10^ kilograms (kg) of sewage sludge
are produced annually in the U.S. (Harrington 1978). An
attractive disposal method for sludge is its application to
agricultural lands or its use in the reclamation of stripped-
mined land. There are problems associated with sludge
disposal by land application. Analysis of sludges indicated
that concentrations of several heavy metals were substantially
higher than in typical soil compositions. Additional con-
taminants that are present in municipal sewage sludge may
be naturally occurring organic compounds and compounds from
industrial processes or other anthropogenic activities.
A particular concern related to the organic compounds
in sludge is the possibility of mutagenic, or genotoxic,
agents being released into the environment (Plewa and Hopke
1983). An environmental mutagen or genotoxin is an agent
that can alter the genetic material or alter the proper
functioning of the genetic material and is released into the
environment. Environmental mutagens are a serious threat to
the public health.
Recently, we analyzed several municipal sludges
(Champaign, Chicago, Hinsdale, Kankakee, and Sauget,
Illinois) using a variety of genetic indicator organisms
to determine their mutagenic properties (Hopke and Plewa,
1982). The Chicago municipal sewage sludge sample had
components that induced a variety of mutagenic responses.
After appropriate concentration, the supernatant liquid was
mutagenic using the Salmonella/microsome assay. Acetone,
hexane, and chloroform:methanol extracts of the pellet
contained promutagens that could be activated by mammalian
microsomes. The data indicate that a moderately potent
agent can be extracted from the sludge since the material
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extracted from only 155 microliters of whole Chicago sludge
induced a doubling in the number of revertant colonies per
plate of strain TA98 following S-9 activation (Hopke et
al. 1982). Samples obtained by further chemical frac-
tionation of the chloroformimethanol extracts from the
Champaign, Hinsdale, and Kankakee sludges showed weak
responses following activation. Only the Sauget sample
demonstrated direct-acting mutagenic activity as well as
very substantial mutagenicity after activation.
We analyzed various sludges for their ability to
induce chromosome damage in Tradescantia. The Tradescantia
data indicated that whole or diluted Chicago sludge induced
chromosome aberrations, measured as micronuclei, in meiotic
cells. The major portion of the mutagens were found to
reside in the sludge solids and not in the aqueous phase.
When whole sludge samples from each municipality were evalu-
ated, a ranking in order of decreasing mutagenic response
was: Sauget, Chicago, Kankakee, Hinsdale, and Champaign.
Thus, there is an apparent correlation of the cytogenetic
potency of the sludge sample and the relative industriali-
zation of the municipality.
Two sludges were analyzed for their ability to induce
point mutations in Zea mays using the maize wx locus pollen
assay. The _in situ tests of sludge-amended soil using
Chicago sludge demonstrated that mutagens were available
to the plant. Toxic as well as mutagenic responses were
observed'. Laboratory studies indicated that Chicago
sludge induced forward mutations in maize pollen grains
but Champaign sludge did not. These studies did not
evaluate the sequestering of mutagens in grain produced
by plants grown on sludge-amended soil.
Another aspect of mutagenic activity in sewage
sludges that requires inquiry is the relationship between
the treatment process and the observed mutagenicity. There
has not been any reported, systematic effort to examine if
different wastewater treatment processes increase or decrease
mutagenicity for the same input stream. It has been observed
that anaerobic incubation of some human feces substantially
increased their mutagenicity to Salmonella and that the
mutagen appeared to be a single compound possibly produced
by anaerobic bacteria. Aerobic incubation did not produce
increased mutagenicity in the same samples (Lederman et
al. 1980). Therefore, the questions arise as to whether
treatment based on anaerobic digestion produces greater
mutagenicity than aerobic digestion and, if so, can the
process be easily modified to lower the mutagenicity of the
resulting sludges? There is a need for a systematic study
of these questions.
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Since most sludges and soils contain extractable
mutagens, the determination of the impact of environmental
mutagens applied to the soil via sludge amendment is diffi-
cult. How much mutagenicity should a sludge possess before
it is deemed to be a hazardous waste? One approach is to
compare the "background level" of mutagenic potency of the
soil upon which sludge is to be added. In a cursory review
of some of our data, we calculated the mutagenic responses
of crude acetone extracts of soil and various whole
sludges when assayed with Salmonella strain TA98 with
mammalian S-9 activation. The comparison is presented
below.
INCREASE OVER
SAMPLE REVERTANTS/mg SOIL RESPONSE
Agricultural soil 12
(Elwood, Illinois)
Champaign sludge 6 0.5
Chicago sludge 173 14
Sauget sludge 780 65
With this rough comparison, the mutagenic potency of a
sludge can at least be compared with the existing environ-
ment. The information from the genetic assays is most
meaningful when they are compared with an appropriate soil
sample.
In summary, work conducted by us and others (Babish et
al. 1983) indicates that municipal sludges demonstrate a wide
range of mutagenic potencies. For sludges to be disposed in
an environmentally safe and economical manner, the mutagenic
component of sludges should be as low as possible. Sewage
treatment methodologies may affect the mutagenic potential
of the resulting sludge, but this relationship has not yet
been studied.
Finally, we must be able to identify rational toxico-
logical limits for sludges. How mutagenic must a sludge be
before it is unsafe to apply to soil? We know that mutagens
from sludge can translocate to crop plants grown on the
amended soil. We are beginning to obtain information on the
rates of degradation of specific compounds in soils and the
degradation of the mutagenicity of sludges in well aerated
3-45
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soils (Brown et al. 1982). However, in order to assess
the risk to humans, we need to know the potential for the
incorporation of mutagens in the food chain. We need to
know if mutagens can be sequestered in the edible parts of
sludge-grown plants such as corn, and if a genotoxic effect
can occur in the cells of mammals that consume such grain.
Thus, there are several areas where we need additional
information to permit us to make competent risk assessment.
These areas include the uptake and sequestering of mutagens
by crop plants, the degradation or percolation of mutagens
in the soil possibly affecting ground water quality, and
erosion of sludge-amended soils into surface waters with
subsequent degradation of water quality. Greater under-
standing in these areas would permit the more accurate
assessment of the risks associated with land disposal of
mutagenic municipal sludges.
REFERENCES
Babish, J.G., B.E. Johnson, and D.J. Lisk. 1983.
Mutagenicity of municipal sewage sludges of American
cities. Environ. Sci. Technol. 17:272-277.
Brown, K.W., K.C. Donnelly, and B. Scott. 1982. The fate
of mutagenic compounds when hazardous wastes are land
treated. In,: Eighth Ann. Res. Symp. Land Disp. Haz.
Waste. EPA-600/9-82-002. pp. 383-397.
Harrington, W.M., Jr. 1978. Hazardous solid waste from
domestic wastewater treatment plants. Environ. Health
Perspect. 27:231-247.
Hopke, P.K., and M.J. Plewa. 1983. The evaluation of the
mutagenicity of municipal sewage sludge. EPA Final
Report. Grant No. R807009. EPA-600/1-83-016. 85 pp.
Hopke, P.K., M.J. Plewa, J.B. Johnston, D. Weaver, S.G. Wood,
and R.A. Larson. 1982. Multitechnique screening of
Chicago municipal sewage sludge for mutagenic activity.
Environ. Sci. Technol. 16:140-147.
Lederman, M., R. Van Tassell, S.E.H. West, M.F. Ehrich, and
T.D. Wilkins. 1980.- In vitro production of human
fecal mutagen. Mutation Res. 79:115-124.
Plewa, M.J., and P.K. Hopke. 1983. Mutagenicity of municipal
sewage sludge. I_n: H.F. Stich (ed.), Carcinogens and
Mutagens in the Environment. CRC Press, Boca Raton,
Florida. pp. 155-175.
3-46
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APPROACHES TO THE FRACTIONATION AND IDENTIFICATION
OF MUTAGENS IN MUNICIPAL SLUDGE
by: M. Wilson Tabor
Departments of Environmental
Health and Microbiology and
Molecular Genetics
and
John C. Loper
Department of Microbiology
and Molecular Genetics
University of Cincinnati
Cincinnati, Ohio 45267
INTRODUCTION
During the past few years, extracts of sludges and
effluent wastewaters from municipal sewage treatment plants
have been shown to be complex mixtures of organic chemicals.
Many of these residue organics have been characterized as
mutagenic in a variety of test systems including bacterial
and plant. Further, the wastewater and sludge residue
organics were shown to include multiple toxic and mutagenic
substances. The major mutagens appeared to be in the
nonvolatile residue organic materials from sewages that
included industrial sources. Although many volatile com-
pounds, including priority pollutants, have been identified
and quantified, the chemical identity and source of the vast
majority of the mutagens is unknown. Chemical characteriza-
tion of these mutagens is necessary to assess the importance
of the compounds as potential hazards to human health and
to develop methods to reduce their concentrations in waste-
waters/sludges.
Progress has been slow toward the identification of the
mutagens. This is due to many factors, including a major
gap in the lack of reliable and reproducible methods for the
isolation of the compounds from wastewaters/sludges for
chemical and biological characterization. Our current
research program is focused to provide the information and
methodologies to fill the gaps in our knowledge of the major
mutagens in wastewaters and sludges.
3-47
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APPROACH
Our approach involves the isolation/concentration of
the residue organics from sludges and waters followed by
fractionation of these complex mixtures using a coupled
bioassay/chemical fractionation method based upon Salmonella
mutagenesis and high performance liquid chromatography
(HPLC) (Loper and Tabor 1983, Loper et al. 1978, Tabor and
Loper 1980). Mutagenic subfractions then are separated
further, as necessary, to permit isolation and identifica-
tion of the bioactive constituents. Structural elucidation
of isolated mutagens is via high resolution techniques
including mass spectrometry and nuclear magnetic resonance
(Tabor 1983). The rationale of this procedure is based upon
our experience with drinking water mutagens (e.g./Loper and
Tabor 1983, Loper et al. 1978, Tabor 1983, Tabor and Loper
1980, 1982, Tabor et al. 1980, 1982).
A biological approach to chemical fractionation of
water residue organics was proposed by Tardiff (Tardiff et
al. 1975). Based largely upon mutagenicity and carcino-
genicity studies of residue organics isolated from drinking
water by Kopfler et al. (1977), Loper and Lang (1978) pro-
posed a coupled bioassay/chemical fractionation procedure
for the pursuit of such biohazardous compounds. Since that
time we and others have investigated:
(1) Alternative methods for the isolation of residue
organics from environmental sources.
(2) The applicability and use of different short term
bioassays of these residue organic mixtures.
(3) Various approaches to chemical fractionation of
the mixtures to characterize the biohazardous
components.
METHODS FOR ISOLATION
Any proposed method for the isolation of mutagens from
sludge or wastewater samples for chemical and biological
characterization should address two specific steps in the
procedure: the isolation of residue organics and the
fractionation of the residue organics for compound identi-
f ication.
3-48
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Isolation of Residue Organics
For the isolation of residue organics, the procedures
employed should be quantitative, reproducible, and should not
chemically interfere with the mutagens, i.e., destroy them
or create artifacts. The most commonly used procedure for
isolating residue organics from sludges has been solvent
extraction (e.g., Babish et al. 1982, Clevenger et al. 1983,
Hopke et al. 1982). Application techniques have included
direct sludge/solvent extraction (Hopke et al. 1982), column
chromatography procedure using lyophilized sludge as a
stationary phase and the extracting solvent as a mobile
phase (Clevenger et al. 1983), and Soxhlet extraction of the
sludge (Babish et al. 1982).
We are investigating three different methods for the
extraction of residue organics from sludges. The first is a
modification of the Soxhlet extraction procedure of Hites
(Elder et al. 1981, Jungclaus et al. 1978) in which the
sludge is first extracted by a polar solvent followed by a
nonpolar solvent. This procedure, originally designed for
the extraction of sediments (Games and Hites 1977, Jungclaus
et al. 1978), extracts a wide range of chemical classes of
compounds. The second method is a modification of the
proposed EPA 624S/625S procedure, originally designed for
the quantitation of priority pollutants (Billets and
Lichtenberg 1983). This procedure utilizes a liquid/solid
extraction method employing sample homogenization with the
extracting solvent following pH adjustments. The third
method for preparing residue organics is our ball mill
procedure in which the sludge is milled with anhydrous
sodium sulfate to a homogeneous powder, of the consistency
of flour, followed by sequential solvent extractions
(nonpolar to polar) of the sample.
These studies have utilized both primary and secondary
sludges from the Cincinnati Mill Creek sewage treatment
facility which is heavily impacted by industrial effluents.
Results to date indicate that all three methods yield
Salmonella-sensitive mutagens in the extracted residue
organics. These data indicate the Hites and ball mill
procedures to be suitable for sludge extraction whereas the
EPA procedure appears to be introducing mutagenic artifacts
to the sample, possibly a result of the extremes of pH
employed in this latter method.
The most commonly used method for the isolation of
residue organics from sewage treatment plant wastewaters has
been XAD (a type of polydivinylbenzene polymer) chromatography
(e.g., Baird et al. 1981, Hopke et al. 1982, Rappaport et
al. 1979). An alternative method that has been successfully
3-49
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used is a liquid/liquid extraction method (Meier and Bishop
1984). We are investigating both methods, utilizing both
influent and secondary wastewaters from the aforementioned
treatment facility. Our results indicate that the XAD
procedure requires the use of a Celite prefiltration column
for the particulate-laden influent wastewater, whereas the
XAD procedure, as we originally employed for studies of
drinking water mutagens (Loper and Tabor 1983, Tabor and
Loper 1982, Tabor et al. 1982), appears to be satisfactory
for secondary effluent wastewaters. The residue organics
obtained to date indicate specific activities for Salmonella
TA98 in the presence of S9 activation in excess of 10,000
net revertants per liter-equivalent for influent wastewater,
and >3,000 (absence of S9) and >3,700 (presence of S9) TA98
net revertants per liter-equivalent for the secondary
effluent wastewater. These results are consistent with
those found by Meier et al. (1984) in studies of residue
organics isolated from the same source by liquid/liquid
ext rac t ion.
Mutagen Isolation
As described above, a biological approach to the
chemical fractionation of residue organics is the method of
choice for the isolation of biohazardous compounds from
complex mixtures. The method we have developed (Loper and
Tabor 1983, Tabor and Loper 1980) has been successful for
the isolation of a previously unidentified mutagen from
drinking water residue organics (Tabor 1983). In this
method, residue organics are separated via high performance
liquid chromatography (HPLC) and fractions are collected for
bioassay and further separation. Subsequent HPLC separations
of the bioactive fractions leads to the isolation of sub-
fractions containing a few or individual components. These
subfractions are further analyzed via high resolution
techniques for compound identification (Tabor 1983). Our
current HPLC investigations of residue organics from sludges
and wastewaters for mutagen isolation indicate that this
procedure is applicable to the separation of such complex
mixtures.
SUMMARY
The overall objective of our work is the isolation
of nonvolatile organic mutagens of municipal sludges and
influent/effluent wastewaters to characterize the mutagens
both chemically and biologically. It is evident from our
work and that of others that more research is needed to
investigate currently existing methods for the extraction of
residue organics from these samples. However, our analytical
3-50
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bioassay/chemical fractionation method for mutagen isolation
from residue organics appears to be well suited to provide
subfractions for mutagen characterization. By providing
more information as to the identity of mutagenic compounds,
their frequency of occurrence, their possible source, and
their levels in treatment plant products, i.e., sludges and
effluent waters, the result of the work will assist in the
definition of waste management procedures.
ACKNOWLEDGEMENT
Supported by U.S. Environmental Protection Agency (EPA)
CR810792-01. This extended abstract does not reflect EPA
policy.
REFERENCES
Babish, J.G., B. Johnson, B.D. Brooks, and D.J. Lisk. 1982.
Acute toxicity of organic extracts of municipal sewage
slude in mice. Bull. Environ. Contam. Toxicol. 29:379-384,
Baird, R.B., C.A. Jacks, R.L. Jenkins, J.P. Gute, L. Neisess,
and B. Scheybeler. 1981. A high-performance macroporous
resin concentration system for trace organic residues
in water, j^n: W.J. Cooper (ed.), Chemistry in Water
Reuse, Vol. 2. Ann Arbor Science Publishers, Inc., Ann
Arbor, Michigan. Chapter 8, pp. 149-169.
Billets, S., and J.J. Lichtenberg. 1983. Interim Methods
for the Measurement of Organic Priority Pollutants in
Sludges, USEPA/EMSL-CIN, Method 624S and Method 625S.
Clevenger, T.E., D.D. Hemphill, K. Roberts, and W.A. Mullins.
1983. Chemical composition and possible mutagenicity
of municipal sludge. WPCF 55:1470-1475.
Elder, V.A., B.L. Proctor, and R.A. Hites. 1981. Organic com-
pounds near dumpsites in Niagara Falls, New York.
Biomed. Mass Spec. 8:409-415.
Hopke, P.K., M.J. Plewa, J.B. Johnston, D. Weaver, S.G. Wood,
R.A. Larson, and T. Hinesly. 1982. Multitechnique
screening of Chicago municipal sewage sludge for
mutagenic activity. Environ. Sci. Technol. 16:140-147.
Jungclaus, G.A., V. Lopez-Avila, and R.A. Hites. 1978.
Organic compounds in an industrial wastewater: a case
study of their environmental impact. Environ. Sci.
Technol. 12:88-96.
3-51
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Kopfler, F.C. , W.E. Coleman, R.G. Melton, R.G. Tardiff,
S.C. Lynch, and J.K. Smith. 1977. Extraction and
identification of organic micropollutants: reverse
osmosis method. Ann. N.Y. Acad. Sci. 298:20-30.
Loper, J.C., and D.R. Lang. 1978. Residue organic mixtures
from drinking water show _in vitro mutagenic and transfor-
ming activity. _ln: M.D. Waters et al. (eds.), Applica-
tion of Short-term Bioassays in the Fractionation and
Analysis of Complex Environmental Mixtures, Vol. 1.
Plenum Press. pp. 513-528.
Loper, J.C., D.R. Lang, R.S. Schoeny, B.B. Richmond,
P.M. Gallagher, and C.C. Smith. 1978. Mutagenic,
carcinogenic, and toxic effects of residual organics in
drinking water. J. Toxicol. Environ. Health 4:919-938.
Loper, J.C., and M.W. Tabor. 1983. Isolation of mutagens
from drinking water: something old, something new.
In: M.D. Waters et al. (eds.), Application of Short-
term Bioassays in the Fractionation and Analysis of
Complex Environmental Mixtures, Vol. 3. Plenum Press,
pp. 165-181.
Meier, J.R., and D.F. Bishop. 1984. Effectiveness of
conventional treatment processes for removal of muta-
genic activity from municipal wastewaters. I_n: 15th
Annual Environmental Mutagen Society Abstracts of
Papers.
Rappaport, S.M., M.G. Richard, M.C. Hollstein, and R.E.
Talcott. 1979. Mutagenic activity in organic wastewater
concentrates. Environ. Sci. Technol. 13:957-961.
Tabor, M.W. 1983. Structure elucidation of 3-(2-chloroethoxy)-
1,2-dichloropropene. A new promutagen from an old
drinking water residue. Environ. Sci. Techol. 17:324-329.
Tabor, M.W., and J.C. Loper. 1980. Separation of mutagens
from drinking water using coupled bioassay/analytical
fractionation. Intern. J. Environ. Anal. Chem. 8:197-215.
Tabor, M.W., and J.C. Loper. 1982. Mutagenic assessment
of a drinking water aquifer recharged by an industrial
river. _Xn: Third Symposium on Application of Short-
term Bioassays in the Fractionation and Analysis of
Complex Mixtures, Chapel Hill, North Carolina, January
1982 .
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Tabor, M.W. , J.C. Loper, and L. Barone. 1980. Analytical
procedures for fractionating non-volatile mutagenic
components from drinking water concentrates. In;
R.L. Jolley et al. (eds.), Water Chlorination:
Environmental Impact and Health Effects, Vol. 3.
Ann Arbor Science Publishers, Inc., Ann Arbor, Michigan.
Chapter 78, pp. 899-911.
Tabor, M.W., J.C. Loper, S.K. Miles, and J. Meier. 1982.
Analytical isolation, separation and identification of
mutagens from non-volatile organics of drinking water.
In: Xllth Annual International Symposium on the
Analytical Chemistry of Pollutants, Amsterdam,
Netherlands, April 1982.
Tardiff, R.G., G.P. Carlson, and V. Simmon. 1975. Halogen-
ated organics in tap water: a toxicological evaluation.
In; R.L. Jolley et al. (eds.), Water Chlorination,
Environment Impact and Health Effects, Vol. 1. pp. 213-227.
3-53
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HEALTH EFFECTS OF ORGANIC PRIORITY POLLUTANTS
IN WASTEWATER SLUDGE — A RISK ASSESSMENT
by: Sydney Munger
Senior Microbiologist
Water Resources Section
Water Quality Division
Municipality of Metropolitan
Seattle (Metro)
Exchange Building
621 Second Avenue
Seattle, Washington 98104
INTRODUCTION
Risk is defined in this presentation as the
of harm occurring to human health as a result of
priority pollutants in land-applied sludge. The
referred to the microbiology paper given earlier
workshop for a discussion on the concept of risk
and the framework used to determine risk.
In the case of priority pollutants, a risk assessment
can be used to define priorities for an industrial pretreat-
ment and source control program in addition to the four
purposes listed in the microbiology paper.
Risk estimation for the reuse of sludge in silviculture,
agriculture, and land reclamation projects will be calculated
in this paper based on the known levels of representative
organic priority pollutants in Metro dewatered sludge.
Predictions on environmental fate were provided by
Michael Overcash based on published literature.
Causative Event
Sludge management options available to Seattle Metro
include silviculture, land reclamation, and composting.
Agriculture is currently not part of the Sludge Management
Plan (Metro 1983a) but will be considered in this analysis
for comparative purposes. Information on priority pollutants
in Metro compost is not available. However, risks involved
in its use should be no greater than those defined for
agricultural use of dewatered sludge. A separate assessment
of risks of compost use cannot be done at this time. Manage-
ment guidelines are defined in Washington state by the
Department of Ecology, and operating practices for Metro are
presented in the Sludge Management Plan (Metro 1983). The
following application rates were used in this assessment:
probability
the organic
reader is
in this
assessme nt
3-54
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• Silviculture — 20 dry tons per acre.
• Land reclamation — 100 dry tons per acre. Sludge
is injected or tilled into the soil at a rate not to
exceed 100 dry tons per acre.
• Agriculture — Up to 20 dry tons per acre. (Metro
does not apply sludge to food chain crops.)
Organic Priority Pollutants in Metro Sludge
The organic priority pollutants, as defined by the U.S.
Environmental Protection Agency (EPA) will be considered to
represent the organic toxicants of greatest concern in this
analysis. For the purpose of this risk assessment it was
necessary to select a few chemicals that could serve as
representatives of larger groups of compounds with similar
physical and chemical characteristics. The criteria considered
when selecting these representative chemicals related to
transport through environmental compartments and toxicity of
the compound. Specifically, these criteria were:
(1) Prevalence in Metro sludge.
(2) Vapor pressure to indicate volatilization loss.
(3) Aqueous solubility to indicate soil-water migration.
(4) Octanol/water partition coefficient to indicate
sorption to soil.
(5) Rate of decomposition.
(6) Toxic dose and availability of dose-response studies.
Based on these criteria, Dr. Michael Overcash recommended
to Metro that the following compounds would serve as good
representatives of the priority pollutants in Metro sludge
to be monitored in a silviculture demonstration site:
(1) Polynuclear aromatic hydrocarbons (PAHs) [phenan-
threne, benz(a)anthracene, benzo(a)pyrene].
(2) Polychlorinated biphenyl (PCB) mixtures.
(3) Phthalates [di-n-butyl pthalate, bis(2-ethylhexyl)
phthalate].
(4) Halogenated short-chain aliphatics (methylene
chloride, chloroform, tetrachloroethylene).
3-55
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From this list I selected four compounds with which to
assess the risk of toxic effects due to organic priority
pollutants in land-applied sludge:
(1) Benzo(a)pyrene [B(a)P]
(2) PCBs
(3) Bis(2-ethylhexyl)phthalate
(4) Chloroform
These selections were based primarily on the toxicity
of the compounds and availability of adequate animal or
human studies demonstrating a dose response.
This paper will be limited to B(a)P, the most toxic of
the PAHs in Metro sludge, and total PCBs. The assumption is
that these compounds or groups of compounds will serve as a
worst case model for other toxic compounds.
Outcomes
The land application of sludge can potentially result
in the transfer of organic toxicants from the sludge to air,
soil, surface water and groundwater, and edible animals and
plants. The Metro organics laboratory has recently quanti-
fied the priority pollutants in Seattle dewatered sludge.
The environmental fate of these compounds, however, has not
yet been studied by this agency.
Using the known concentrations of representative
compounds in Metro sludge, the published literature on
environmental fate and physical and chemical characteristics
of the compounds, Michael Overcash estimated their fate in
sludge land projects. Tables 1 and 2 give these estimated
concentrations for benzo(a)pyrene [B(a)P] and polychlorinated
biphenyls (PCBs) in environmental compartments as a result
of silviculture, land reclamation, and agricultural applica-
tions of sludge (Overcash 1983).
Background Levels of PCBs and B(a)P
The levels of PCBs and B(a)P contributed to the environ-
ment by the land application of sludge should be compared to
background levels of these compounds to gain perspective of
any increased risk. PCBs have been observed in water, food,
soils, sediments, and animal and human tissue sampled
throughout the world. PCB levels in food are gradually
declining as a result of restrictions on their use, but as
of 1975 were commonly in the part per million range. The
teenage male in 1975 was estimated to consume 8.7 micrograms
of PCBs per day (Jelinek and Corneliussen 1976, as reported
in U.S. EPA 1980).
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TABLE 1
ESTIMATED CONCENTRATIONS OF PCBs IN SELECTED ENVIRONMENTAL
COMPARTMENTS RESULTING FROM SLUDGE LAND APPLICATION (Overcash 1983)
CONCENTRATION (parts ber billion)
ENVIRONMENTAL
COMPARTMENT
SILVICULTURE
LAND RECLAMATION
AGRICULTURE
Sludge-soi1
26-18 (12 months)
130-90
(12 months)
22 (6-9 months)
Control soil
<10
<10
<10
Groundwater
<0.01
<0.01
<0.01
Surface water
<0.01
<0.01
<0.01
Blackberry
0.2-1
1-5
0.2-1
Crops (fruits and
NAa
NA
0.2-1
vegetables)
Control blackberry'3
0.02-0.2
0.02-0.
2
0.02-0.2
Control cropsc
NA
NA
<50
Deer tissue
<0.05
<0.05
NA
Control deer tissue
<0.05
<0.05
NA
Deer fat
10-12
50-60
10-12
Control deer fat
<0.05
<0.05
<0.05
Cattle (beef fat)
NA
NA
10-12
Control cattle (beef fat)
NA
NA
<0.05
Milk fat
NA
NA
Unknown
Control milk fat
NA
NA
Up to 1,900
aNA = Not applicable.
^Based on values measured in grapes (Pucknat 1981).
cBased on values measured in commercial fruits and vegetables (Pucknat 1981).
-------
TABLE 2
ESTIMATED CONCENTRATIONS OF B(a)P IN SELECTED ENVIRONMENTAL
COMPARTMENTS RESULTING FROM SLUDGE LAND APPLICATION (Overcash 1983)
CONCENTRATION (parts ber billion)
ENVIRONMENTAL
COMPARTMENT SILVICULTURE LAND RECLAMATION AGRICULTURE
Sludge-soil
2-60 (12 months)
10-300 (12 months)
10
Control soil
1-10
Groundwa ter
<0.01
<0.01
<0.01
Surface water
<0.01
<0.01
<0.01
Blackberry
0.2-6 (12 months)
1-30
0.3-3
Crops (fruits and
NAa
NA
0 . 1-1
vegetables)
Control blackberry*3
0.0 2-0 . 2
0.0 2-0 . 2
0.0 2-0.2
Control crops0
0.01-30
NA
0.01-30
Deer tissue
Unknown
Unknown
Unknown
Control deer tissue
Unknown
Unknown
Unknown
Beef cattle
NA
NA
Unknown
Control beef cattle
Raw beef
NA
NA
<0.05
Cooked beef
NA
NA
3 .5-50 .4
Milk fat
NA
NA
Unknown
Control milk fat
NA
NA
Unk nown
aNA = Not applicable.
^Based on values measured in grapes (Pucknat 1981).
cBased on values measured in commercial fruits and vegetables (Pucknat 1981).
-------
B(a)P is a natural as well as anthropogenic component
of the environment. The major sources are related to
combustion products created during power generation, refuse
burning, coke production, and motor vehicle travel. The
levels of B(a)P found in food and water are directly related
to their proximity to sources of B(a)P. In 1980, the U.S.
EPA estimated the average human consumption of B(a)P per day
to be 160 to 1,600 nanograms (ng) (U.S. EPA 1980b).
Exposure
To help understand the probability of exposure to B(a)P
or PCBs in the environment, the pathways for organic toxicant
transport are diagrammed in the Metro Risk Assessment (Metro
1983b). The potential routes of transmission can be found
in "Wastewater Sludge Microbiological Health Effects and
Risk Assessment" presented earlier in these proceedings.
Consequences
PCBs
The International Agency for Research on Cancer (IARC)
and the U.S. EPA have concluded that PCBs are animal carcin-
ogens and potentially human carcinogens. A study by
Kimbrough et al. (1975) was used by the U.S. EPA (1980a)
to calculate the level of risk associated with the ingestion
of PCBs. Using the linearized multistage model developed by
Crump (Fed. Reg. 4j5 ( 230), 1980), it was concluded that
ingestion of 204 ng PCBs per day by a 70 kilogram (kg)
person was equivalent to a lifetime cancer risk of 10"^.
In 1975 the average daily consumption was 8,700 ng.
The risk estimation combined with predicted amounts of
PCBs in selected environmental compartments as a result of
sludge land application can be used to calculate quantities
of food, soil, and water which can be consumed without
exceeding an excess lifetime cancer risk of 10"^. Surface
water and groundwater consumption will not be limited by
PCBs from a sludge application. Blackberries and other food
crops can take up PCBs but 200 to 1,000 grams (g) per day
can still be ingested if the plants are growing in a sludge-
amended forest or farm. Consumption of edible berries from
a land reclamation site should be limited to 40 to 200 g per
day.
Deer can accumulate PCBs in fat tissue, leading to
elevated levels. Intake of deer fat should be limited
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to 20 g per day for silviculture and 4 g for land reclama-
tion to keep the excess lifetime cancer risk at or below
10~5. The palatability of deer fat makes it unlikely to
be a significant contribution to PCB body burden.
PCB levels in the soil will be elevated as a result of
sludge application and, after an initial decline, remain
elevated for many years. Children with a tendency to eat
dirt may be at increased risk if they were to play daily in
a sludge-amended area. However, in a silviculture or
agriculture site, they would have to eat 8 to 10 g of soil
per day to increase the level of risk above 10~5. in a
land reclamation site 1 to 2 g of soil ingested daily would
yield the same risk. In all cases it is unlikely that a
child would be exposed to sludge-amended areas on a daily
basis.
B ( a ) P
Short term mutagen assays and long term animal testing
support the conclusion that B(a)P is a potent mammalian
carcinogen. Epidemiological studies of coke oven and
coal tar industry employees implicate B(a)P as a human
carc inogen.
A study by Neal and Rigdon (1967) was used by the U.S.
EPA (1980b) to estimate the risk associated with ingestion
of B(a)P. As with PCBs, the Crump model was used to
extrapolate the observed risk to low dose human exposure
levels. It was concluded that consumption of 61 ng per
day was equivalent to a lifetime cancer risk of 10"^.
The average daily consumption of B(a)P is estimated at
160 to 1,600 ng.
The probability that B(a)P in a sludge land application
project could cause an excess cancer risk greater than
10~5 can be estimated by the quantities of environmental
compartments which can be ingested without exceeding
61 ng/day B(a)P. In all types of sludge application dis-
cussed in this paper, neither surface water nor groundwater
will be impacted by a detectable increase in B(a)P concen-
trat ions.
The addition of sludge to forest or rural soils will
cause an initial increase in the concentration of B(a)P
in the surface soil. During the initial 6 to 12 months
following a silviculture or agriculture sludge application,
children with a tendency to eat dirt are at an increased
risk of exceeding 61 ng/day of B(a)P if they eat from 1 to
30 grams of soil per day. After one year the levels of B(a)P
contributed by the sludge are estimated to have returned
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to background concentrations. Background levels and thus
background risk will not be reached in land reclamation for
12 to 24 months.
Silviculture and land reclamation applications can
impact the human food chain and increase risks if wild
berries and game animals bioconcentrate B(a)P in edible
tissues. If the growing season started within a few months
of sludge application, the blackberries could contain
elevated B(a)P levels. Limiting consumption of sludge-grown
blackberries on a silviculture site to 10 to 100 g per day,
compared to 300 to 1,200 g per day of control blackberries,
would be required to remain at or below a lifetime cancer
risk of 10" . On a land reclamation site consumption
would be limited to 2 to 20 g per day for the same level of
risk.
Estimation of risk due to consumption of deer or cattle
tissue is not possible due to a lack of information on
uptake of animals. However, the B(a)P in the raw meat would
be significantly less than in the cooked meat. In other
words, the cooking process will determine the B(a)P content
of the meat to a greater extent than the quantity of B(a)P
ingested by the deer or cow.
In an agricultural project, where crops are not planted
until 6 to 9 months following sludge application, the B(a)P
concentration in the sludge-soil mix will have been degraded
to approximate that of control soils and should not lead to
excess risk.
CONCLUSIONS
Prediction of risk resulting from priority pollutants
in wastewater sludge is possible utilizing available published
research if several assumptions are accepted. In this paper
PCBs and B(a)P were used as representatives of the priority
pollutants and should reflect a worse case analysis. It was
predicted that levels of these compounds would be increased
in soil, food, and animals. However, any increased risk
identified would be minimal and can be controlled by proper
site management.
As a municipality facing continuous production of 200
tons per day of dewatered sludge, we feel that sufficient
research is available to justify proceeding with an opera-
tional program. We do remain committed, however, to assuring
the people of our region that what we do is environmentally
sound — that's want the organization was built on and remains
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loyal to. It is with this in mind that we are proposing
comprehensive monitoring programs on operational demonstra-
tion sites to validate our risk assessment predictions.
Such a monitoring program would measure the environmental
fate of representative compounds and organisms for each
transport pathway. It is the position of Metro that demon-
stration projects of this type should receive high priority
when federal funding decisions are made.
REFERENCES
Federal Register. 1980 . Vol. 4_5_ ( 230 ): 79347.
Jelinek, C.E., and P.E. Corneliussen. 1976. Levels of PCBs
in the U.S. food supply. I_n: Natl. Conf. Polychlor.
Biphenyls, Chicago, Illinois. EPA 5 60/6-75-004.
Office of Toxic Substances, U.S. Environmental Protec-
tion Agency, Washington, D.C.
Kimbrough, R.D., et al. 1975. Induction of liver tumors in
Sherman Strain female rates by polychlorinated bipheynl
Aroclor 1260. Jour. Natl. Cancer Inst. 25:553.
Metro. 1983. Sludge Management Plan. Metro Report.
Municipality of Metropolitan Seattle.
Metro. 1983. Metro Risk Assessment. Metro Report.
Municipality of Metroplitan Seattle.
Neal, J., and R.H. Rigdon. 1967. Gastric tumors in mice fed
benzo(a)pyrene: a quantitative study. Texas Rpts.
Biol. Med. 25 :553 .
Overcash, M. 1983. Identification and selection of organic
priority pollutants at Pilchuck Demonstration Site.
Report to Metro. Municipality of Metropolitan Seattle.
10 pp.
Pucknat, A.W. 1981. Health Impacts of Polynuclear Aromatic
Hydrocarbons. NDC, Park Ridge, New Jersey.
U.S. EPA. 1980a. Ambient Water Quality Criteria for
Polychlorinated Biphenyls (PCBs). U.S. Environmental
Protection Agency, Washington, D.C.
U.S. EPA. 1980b. Ambient Water Quality Criteria for
Polychlorinated Aromatic Hydrocarbons (PAHs). U.S.
Environmental Protection Agency, Washington, D.C.
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SUMMARY ON THE DISCUSSION FROM THE WORKSHOP ON
ORGANIC CHEMICALS IN SLUDGE
by: F. Bernard Daniel
Bioassay Branch
Toxicology and Microbiology Division
Health Effects Research Laboratory
U.S. Environmental Protection Agency
26 West St.Clair Street
Cincinnati, Ohio 45268
In contrast to the general conclusions presented in the
Denver Workshop (March 1983), there was a consensus at this
workshop that organic chemicals in municipal sludge may,
under some conditions, represent a human health risk.
Actual estimates of those risks, however, are complicated by
the wide ranges in the concentrations and the types of
organics present in sludge and by the numerous potential
routes of human exposure that ensue from the many disposal
options (Table 1). The followng paragraphs summarize the
discussions of the workshop panel that followed the formal
presentat ions.
What Is the Best Type of Risk Assessment For Municipal
Sludge?
A considerable portion of the discussion focused on
what methodology is the most appropriate to use in asses-
sing the health risks associated with sludge. Several types
of risk assessment procedures might be applicable:
(1) A target chemical (criteria pollutant) methodology.
(2) A bioassay (complex mixture) methodology.
(3) Some combination of these two methodologies.
Each approach has inherent advantages and limitations
with respect to the assessment of health hazards associated
with a particular sludge usage. For example, a criteria
pollutant approach presupposes that it is possible to
construct a list of chemicals for which scientifically
defensible action levels could be constructed and from which
a realistic assessment of risk presented by the whole sludge
could be calculated from a direct summation of the individual
risks associated with each criteria chemical. Further, the
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TABLE 1
FACTORS WHICH COMPLICATE THE ASSESSMENT OF RISKS
ASSOCIATED WITH ORGANIC CHEMICALS IN MUNICIPAL SLUDGE
I. SLUDGE COMPOSITION (array of organics present)
A. Source of influent wastewater — domestic vs.
industr ial
B. Type of treatment process at POTW
II. SLUDGE USAGE (exposure parameters)
A. Distribution and marketing
B. Composting
C. Agricultural land application
D. Silviculture
E. Incineration
F. Ocean dumping
G. Landfill
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criteria pollutant method assumes that such an approach
would be valid even though the chemical composition of the
sludges from different municipalities could be expected to
vary considerably. It would not be easy to develop such a
list, and, in fact, it is not clear how it might be done.
The advantage of the bioassay approach is that it
evaluates the selected toxicological parameter directly on
the specific sludge (i.e., does not "miss" a noncritical
toxicant). In addition, bioassays may also detect synergistic
interactions among toxicants. On the other hand, it would
be difficult to select a bioassay battery that would generate
data directly useful in an actual risk assessment. In
addition, neither risk assessment methodology (criteria
pollutant or bioassay) would be useful until £ reliable
exposure assessment for the particular disposal option in
question is developed. This latter point reinforces the
idea that the risk assessment must take into account the
disposal methodology. A highly developed risk assessment
scheme for sludges, presented by Sydney Munger of Seattle
Metro, represents these points very well. The Seattle
approach is a criteria pollutant method (for two chemicals,
benzo(a)pyrene and total PCBs), based on one toxicological
endpoint (cancer), and developed for specific disposal
scenarios (silviculture and land reclamation) for which an
exposure estimate is predicted.
The Office of Water Regulations and Standards (OWRS) is
developing a list of criteria chemicals for sludge because
they believe that, at this time, enforceable regulation will
not result from bioassay data. This point received consider-
able debate but was not convincingly refuted even with
respect to the area of genetic toxicology — a discipline
with a relatively simple mechanistic basis and relatively
extensive test development. On the other hand, a cursory
examination of the data on the frequency of detection of
just the 129 priority pollutants shows that there is great
variance in the occurrence and concentrations of organic
chemicals in sludge. Thus, the possibility of developing a
single list of criteria chemicals that might be used to
meaningfuly assess the potential health risks of all municipal
sludges is dubious.
What Uses of Sludge Are Most Likely to Result in Significant
Human Exposure?
A general consensus among workshop participants was
that the distribution and marketing (D&M, or giveaway)
programs presented the most uncontrolled use situation and,
perhaps, the most likely occasion for direct human exposure.
The data presented by Robert Bastian, from the Office of
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Water Program Operations (OWPO), indicated that D&M programs
still constitute a significant sludge disposal option for
some publically owned treatment works (POTWs). On the
other hand, Lewis Nay lor of Cornell University presented an
exposure assessment in which he concluded, using some
conservative assumptions, that the likelihood for human
exposure to organics from sludge would be small even in D&M
programs that include gardening uses.
Are There Sufficient Data on the Range of Types of Organic
Chemicals Present in Sludge?
Considerable detailed information on the frequency of
occurrence and concentrations of the priority pollutants is
available from several recent studies by the EPA's Effluents
Guidelines Division and the Municipal Environmental Research
Laboratory (MERL). Other recent studies, by the city of
Seattle, Washington, and Muskegon County, Michigan, for
example, have expanded the list of organics detected in
municipal sludge.
The Muskegon study in particular points out the short-
comings of the priority pollutant list in that the average
concentration of a number of non-priority pollutant organics,
selected on the basis of the known industrial discharge, was
much higher. The Muskegon study (Table 2) also points out
the importance of industrial discharge on the organic
profile since 3,3-dichlorobenzidine, a carcinogenic aromatic
amine, was present at very high concentrations (44 parts per
million) in the Muskegon sludge. This compound, which
appeared at only very low levels and in only a few percent
of the samples from the Effluent Guidelines 49-city study,
was probably result of the discharge from a dye factory into
the Muskegon County POTW.
The more general point illustrated by this example is
that the organic (and probably the inorganic) profile of
chemicals that might be found in a particular sludge is
likely influenced by the type of and extent of industrial
discharge into the influent wastewater. This site-specific
nature of the organic chemical profile is a major impediment
to the rational development of a criteria pollutant-by-
pollutant approach to municipal sludge risk assessment.
Another clear example of the inadequacy of a chemical-
specific approach is the very high level of mutagenic
activity associated with the sludge from Sauget, Illinois.
The extreme genotoxic nature of this sludge cannot be
accounted for by routine chemical analysis. The list of
criteria chemicals would have to take into account the
intensive diversity of the types of organics that might be
discharged by the various industries present.
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TABLE 2
ORGANIC CHEMICALS DETECTED IN MUNICIPAL
SLUDGE AFTER EXTENDED AERATION
AVERAGE
(micrograms/
PRIORITY POLLUTANTS
kilogram)
Butylbenzylphthalate
280
Benzo(a)anthrac ene
60
Bis(ethylhexyl)phthalate
4,200
1,4-dichlorobenzene
20 0
1,2-dichlorobenzene
320
Di-n-butylphthaiate
340
3,3'-dichlorobenzidine*
44 ,000
Fluoranthene
230
Fluorene
140
Naphthalene
580
Phenanthrene
810
Phenol
240
Pyrene
200
Toluene
730
ADDITIONAL ORGANIC COMPOUNDS
2-chloroaniline*
26,600
Cresol
1,100
2 , 21-dichloroazobenzene*
1,400
Diethoxychlorobenzene
4 ,000
Dimethyl naphthalenes
9,400
2,4'-diamino-3,3'-dichlorobiphenyl 35,000
Methyl naphthalenes
2,600
Substituted alkyl benzenes
40,000
Trimethyl naphthalenes
7,300
Tributyl phosphate
800
Source: Demirjian et al. 1983.
*Suspect carcinogen. Not observed in
Effluent Guidelines Division Study.
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Another factor that could affect the organic chemical
profile of a sludge would be the type of treatment process
employed at the particular POTW. There is probably consider-
ably less information on the specific efforts of this
variable. This point was clearly illlustrated by the
Effluent Guidelines Study.
What Is Known About the Stability of Toxic Organics in
Various Media, e.g., Sludge, Soil, Water?
The consensus of the workshop was that the stability of
the toxic organics in the sludge and soil is a critical area
in which we presently have relatively little usable data.
For example, a chemical that is a relatively weak toxicant
yet is stable in soil would tend to accumulate with repeated
applications; such a compound would be of greater concern
than a more toxic compound that rapidly decomposes upon
exposure to air, bacteria, or light. Likewise, it is
important to know the relative propensity of these chemicals
to bioaccumulate in either plants or animals. Michael
Overcash from North Carolina State University presented some
preliminary findings that suggest that some of these fate
and transport questions might be addressed by considering
chemical classes rather than individual compounds. If this
were to be found a generally valid approach, it might
greatly simplify the problems of fate, transport, and
exposure assessment. This is clearly one of the areas most
needing additional study.
How Can Bioassays Be Used in the Risk Assessment Process
for Sludge?
This broad question was discussed implicitly in almost
all aspects of the workshop deliberations. This question is
particularly critical given the limitations of the criteria
pollutant approach to risk assessment mentioned earlier. As
mentioned, there was a general consensus of the workshop
group that bioassay information could not be used to develop
enforceable regulations. There is some justification
for this view since the majority of the discussion concerning
bioassays on municipal sludge was focused on the lower
tiered short-term genotoxicity assays such as the Ames test.
Unfortunately, the discussion was somewhat misdirected
because, in the philosophy of the conventional tiered
testing scheme, tier 1 and 2 tests are not used for quantita-
tive risk assessment but rather for exploratory and confirma-
tory purposes respectively (Figure 1). Quantitative risk
assessment is conducted on the results of tier 3 testing.
For cancer the accepted tier 3 test is the NTP chronic
3-68
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FIGURE 1.
TIER 1 AND TIER 2 TESTS.
3-69
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lifetime tumor assay in rats and mice. This is the only
test from which acceptable risk assessments for cancer can
be made. Estimates of risk cannot be made from tier 1 and
tier 2 test data. Thus, the appropriate question to ask is:
"Can tier 3 tests be conducted on sludge or sludge samples?"
Using cancer as an example of a toxic endpoint, the answer
would probably be no. The reason is that, although one
might secure a sufficient sample of a given sludge for a
long-term cancer bioassay, it is not realistic to conduct
such an expensive test on a sample with a composition that
is very site-specific (i.e., dependent on industrial input)
and subject to temporal variations. Thus, if it is accepted
that only tier 3 assay data can be used for risk assessment
and that tier 3 tests cannot be conducted on these environ-
mental samples, then it is unlikely that risk assessments
for genetic toxicology can be made solely on the basis of
bioassays.
Bioassays do, however, have certain important advantages
over criteria pollutant approach. The most important
advantage is that the actual toxic potential of the sample
per se is assessed and the possibility of missing a toxic
non-criteria chemical is eliminated. Thus, although the
tier 1 and 2 assays cannot be used for risk assessment, they
can be extremely useful for risk identification. They can
be used to flag potentially hazardous sludges. Once a
sludge has been indicated on the basis of bioassay analysis
as being of special concern , other operations, such as
chemical analysis or control over the input (industrial
discharge), could be initiated. An example of how bioassays
mght be used in conjunction with chemical analysis and
control technology in sludge management is shown in Figure 2.
With respect to classical toxicological endpoints,
however, the issue is simplified since there are no generally
accepted in vitro or short-term tests which might be predic-
tive of chronic toxicity. Consequently for toxic endpoints
other than cancer we have, in reality, only one test (i.e.,
90-day-subchronic test) which is applied in lieu of a tier 1
test and from which a risk assessment can be made.
SUMMARY
There is considerable uncertainty as to exactly how
serious of a health hazard the organic chemicals in sludge
are. It is clear that the level of risk depends on the
quantitative and qualitative aspects of the chemical types
present and on the methodology used. The first factor
(i.e., the chemical types in the sludge) is a function of
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the industrial discharge entering the POTW. Several critical
questions must still be addressed through more research
efforts:
(1) What approach should be taken in developing risk
assessment methods for the organic chemicals in
sludge? Can a meaningful chemical-specific approach
be developed for a complex mixture like municipal
sludge? Does the complex mixture aspect of the
problem indicate a need for using a toxicologica1
(or bioassay) methodology in at least a screening
mode? These issues must be carefully considered if
the research effort is to make meaningful improvements
in the estimates made for the various sludge disposal
options. Further, if a bioassay approach to risk
assessment is to be developed, we must give consider-
ation to the attendant fate and transport (exposure)
issues.
(2) What is the human health hazard with respect to
carcinogenicity, heritable mutations, and reproduc-
tive effects from a mixture that is mutagenic?
How can these relative hazards be compared among
different mixtures using mutagenic activity as the
only available data?
(3) What chemical types in sludge are likely to be of
most concern? What is the major route of exposure
for the various chemical types? How stable are
these compounds in the soil, in water, or in the
sludge itself? Do they tend to accumulate in plant
or animal life — especially those organisms that
are in the human food chain? Can we develop
generalizations about the fate and stability of
these chemicals of concern by studying the proper-
ties of chemical classes?
(4) Next to D&M disposal methods, what other disposal
and usage options represent the most likely oppor-
tunities for human exposure?
The workshop concluded with a general consensus that
there are many questions left to be answered about both the
types of organics that might appear in sludge and in what
situation they might present a significant human health
risk. It is clear that efforts must be made in the immediate
future, based on the best available scientific data, to
begin to develop sludge regulations. On the other hand,
if a more efficient sludge management policy is to be
developed, a more complete scientific data base will be
needed. In the long term a directed research effort will be
necessary to answer some of the questions raised in the
discussion and thereby permit the construction of defensible
and enforceable sludge management.
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APPENDIX A
MUNICIPAL WASTEWATER SLUDGE HEALTH
EFFECTS RESEARCH PLANNING WORSHOP
PARTICIPANTS AND OBSERVERS
-------
PARTICIPANTS
Dr. John G. Babish
Dept. of Preventive Medicine
New York State College of
Veterinary Medicine
Cornell University
Ithaca, NY 14853
607-256-5454
Mr. Jim Rasilico
OEET/U.S. EPA (RD-681)
401 M Street, S.W.
Washington, DC 20460
Mr. Robert K. Bastian
U.S. EPA (WH -556)
401 M Street, S.W.
Washington, DC 20460
202-382-7378
Dr. Kirk Riddle
CANTEB, HSS15 9
Division of Toxicology
Bureau of Foods, FDA
200 C Street, S.W.
Washington, DC 20204
20 2-472-5705
Dr. Randy Bruins
ECAO/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
Dr. Richard Bull
HERL/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
Dr. Rufus Chaney
US DA
Building 008
Bare-West
Beltsville, MD 20705
202-344-3324
Dr. Ben Chen
U.S. EPA/Region IV
345 Courtland Street, N.E.
Atlanta, GA 30365
Dr. F. Bernard Daniel
HERL/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
513-684-7482
Dr. Joseph Farrell
MERL, WRD/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
513-684-7645
Dr. Lee Jacobs
Department of Crop and
Soil Sciences
Michigan State University
East Lansing, MI 48824
517-353-7273
Mr. Walter Jakubowski
HERL/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
513-684-7385
Mr. Elliot Lomnitz
OWRS/U.S. EPA (WH-5 85)
401 M Street, S.W.
Washington, DC 20460
Dr. Cecil Lue-Hing
Director
Research and Development
Metropolitan Sanitary District
of Greater Chicago
100 East Erie Street
Chicago, IL 60611
312-751-5734
Dr. Bob McGaughy
ORD/U.S. EPA (RD-68 9)
Washington, DC 20460
20 2-382-7341
Ms. Sydney F. Munger
Water Resources Section
Water Ouality Division
Municipality of Metropolitan
Seattle
Exchange Building
621 Second Avenue
Seattle, WA 98104
20 6-223-4860
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Dr. Lewis M. Naylor
Dept. of Agricultural Engineering
Cornell University
Ithaca, NY 14851
607-256-2173
Mr. Tom O'Farrell
OWRS/U.S. EPA (WH-551)
401 M Street, S.W.
Washington, DC 20460
Dr. Michael Overcash
Dept. of Chemical Engineering
North Carolina State University
Raleigh, NC 27695-7905
919-737-2325
Dr. Michael J. Plewa
Environmental Research Laboratory
University of Illinois
1005 West Western Avenue
Urbana, IL 61801
217-333-3614
Dr. Sheila Rosenthal
OHEA/U.S. EPA (RD-689)
401 M Street, S.W.
Dr. Charles A. Sorber
Office of the Dean
College of Engineering
University of Texas at Austin
Austin, TX 78712-1080
512-471-4397
Mr. Charles Spooner
U.S. EPA (WH-556)
401 M Street, S.W.
Washington, DC 20460
202-382-5684
Mr. Wade Talbot
OHR/U.S. EPA (RD-683)
401 M Street, S.W.
Washington, DC 20460
Dr. M. Wilson Tabor
Institute of Environmental
Health
Location 56
University of Cincinnati
Medical Center
Cincinnati, OH 45267
513-872-4830
Washington, DC 20460 Dr. John Walker
202-382-7334 U.S. EPA (WH-556)
Washington, DC 20460
Dr. Jim Ryan 202-382-7371
MERL/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
Dr. Bernard Sagik
Vice President for Academic Affairs
Drexel University, 1-203
32nd and Chestnut
Philadelphia, PA 19104
215-895-2200
A-2
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OBSERVERS
Dr. Scott Clark
Dept. of Environmental Health
University of Cincinnati
Medical Center
Cincinnati, OH 45267
Dr. Lyman Condie
HERL/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
Mr. Mike Conti
OPA/IEMD/U.S. EPA
401 M Street, S.W.
Washington, DC 20460
Mr. John Convery
MERL/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
Mr. Thomas L. Gleason, III
OEET/U.S. EPA (RD-681)
401 M Street, S.W.
Washington, D.C. 20460
Dr. Walter Grube
MERL/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
Dr. Philip Hopke
Environmental Research Laboratory
University of Illinois
305 West Western Avenue
Urbana, IL 61801
Mr. Dave Kleffman
OHR/U.S. EPA (RD-68 3)
401 M Street, S.W.
Washington, DC 20460
Dr. Fred Kopfler
HERL/U.S.EPA
26 West St. Clair Street
Cincinnati, OH 45268
Dr. Norm Kowal
HERL/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
Dr. Bala Krishnan
OEET/U.S. EPA (RD-681)
401 M Street, S.W.
Washington, DC 20460
Dr. John Loper
Dept. of Microbiology
University of Cincinnati
Medical Center
Cincinnati, OH 45267
Mr. Lee McCabe
HERL/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
Mr. Bruce Mintz
OWPO/U.S. EPA (WH 5 47)
401 M Street, S.W.
Room 1133 East Tower
Washington, DC 20460
Dr. Michael Pereira
HERL/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
Dr. Frank Schaefer
MERL/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
Dr. Jerry Stern
MERL/U.S. EPA
26 West St. Clair Street
Cincinnati,OH 45268
Dr. Al Venosa
MERL/U.S. EPA
26 West St. Clair Street
Cincinnati,OH 45268
Ms. Brenda Washington
ORPM/U.S. EPA (RD-67 4)
401 M Street, S.W.
Washington, D.C. 20460
Dr. Doug Williams
CERI/U.S. EPA
26 West St. Clair Street
Cincinnati, OH 45268
A-3
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Dr. Annan F. Yanders
Director, Environmental Trace
Substances Research Center
University of Missouri
Route #3
Columbia, MO 6 5 201
A-4
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APPENDIX B
MUNICIPAL WASTEWATER SLUDGE HEALTH
EFFECTS RESEARCH PLANNING WORKSHOP
AGENDA
-------
MUNICIPAL WASTEWATER SLUDGE HEALTH EFFECTS
RESEARCH PLANNING WORKSHOP
MICROBIOLOGY SESSION
January 10-11, 1984
AGENDA
Tuesday, January 10th:
8:30 - 8:45 Welcome; Introductions Dr. Richard Bull
HERL/EPA
8:50 - 9:05 HERL Perspective on Microbiology Health
Effects — Definition of the Problem Mr. Walter Jakubowski
HERL/EPA
9:05 - 9:20 Sludge: Regulatory, Research, and Working
Definitions Mr. Robert K. Bastian
OWPO/EPA
9:20 - 9:45 Qjantity, Quality, and Mode of Current and
Projected Sludge Disposal Mr. Robert K. Bastian
OWPO/EPA
9:45 - 10:15 Philosophy and Efficacy of PSRP and PFRP —
Numerical versus Process Standards Mr. Joseph B. Farrell
HERL/WRD/EPA
10:15 - 10:30 Break
10:30 - 11:00 Sludge Microbiological Health Effects
and Risk Assessment — the Seattle Metro
Approach Ms. Sydney Munger
Seattle Metro
11:00 - 11:30 Sludge Microbiological Health Effects Issues
and the Epidemiological Approach Dr. Bernard P. Sagik
Drexel University
11:30 - 12:00 Alternate Approaches (Sentinel Animals,
Monitoring, and Modeling) to
Microbiological Risk Assessment Dr. Charles A. Sorber
University of Texas
at Austin
12:00 - 1:00 Lunch
1:00 - 1:30 Microbiological Risk Assessment of Sludges:
Data Required by EPA Dr. Sheila L. Rosenthal
OHEA/EPA
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1:30 - 4:30 Organizational Responsibilities, Viewpoints,
and Approaches:
Mr. Charles S. Spoone
EPA
Dr. Rufus L.
USC&
Chaney
Dr. Kirk Biddle
FEA
Wednesday, January 11th:
8:30 - 9:00
Identification of Significant Data Gaps and
Coable Research Tasks
Dr. Cecil Lue-Hing
Metropolitan Sanitary
District of Greater
Chicago
Dr. John Walker and
Mr. Walter Jakubowski
EPA (discussion
leaders)
9:00 - 11:30
Develop and Prioritize Multi-Year Research
Plan (HERL and OWPO)
11:30 - 1:00
Lunch
R-2
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MUNICIPAL WASTEWATER SLUDGE HEALTH EFFECTS
RESEARCH PLANNING WORKSHOP
ORGANIC CHEMICALS SESSION
January 11-12, 1984
AGENDA
Wednesday, January 11th
1:00 - 1:20 Organics in Municipal Sludge: Definition of
the Problem Dr. F. Bernard Daniel
HERL/EPA
1:20 - 1:50 Status Report on Toxic Organics of Concern
in Sewage Sludge Mr. Charles S. Spooner,
OW/EPA
1:50 - 2:20 Types and Concentration of Organics in
Municipal Sludge Dr. Lee W. Jacobs
Michigan State
University
2:20 - 2:50 Transfer of Organics frcm Municipal Sludge
to Soil Dr. Lewis M. Nay lor
Cornell University
2:50 - 3:00 Break
3:00 - 3:30 The Stability and Mobility of Organics
in Soil Dr. Michael R. Overcash
North Carolina
State University
3:30 - 4:00 Toxicological Studies for the Assessment
of Risk Associated with Municipal Sludge .. Dr. John G. Babish
Cornell University
4:00 - 4:30 The Use of Mutagenicity Data for Assessing
Municipal Sludge Dr. Michael J. Plewa
University of
Illinois
4:30 - 5:00 Approaches to the Fractionation and
Identification of Mutagens in Municipal
Sludge Dr. M. Wilson Tabor
University of
Cincinnati
B—3
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Thursday, January 12th;
8:30 - 9:00
9:00 - 10:20
10:20 - 10:30
10:30 - 11:30
11:30 - 1:00
1:00 - 1:30
1:30 - 2:30
2:30 - 2:40
2:40 - 3:30
Health Effects of Municipal Sludge: A Risk
Assessment
Discussion of the Scientific Data Base,
Identification of the Issues
Break
Discussion of Specific Issues Previously
Identified
Lunch
Further Discussion of Specific Issues
Discussion of Research Needs and Information
Needed for Making Quantitative Risk
Assessments
Break
Final Discussions: Rank Research Needs,
Determine Areas of Consensus and
Controversy
Ms. Sydney Munger
Seattle Metro
Dr. F. Bernard Danj
HERL/EPA
(discussion leader)
B-4
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APPENDIX C
LIST OF ACRONYMS AND ABBREVIATIONS
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APPENDIX C
LIST OF ACRONYMS AND ABBREVIATIONS
Ah Aryl hydrocarbon
CANTEB Contaminants and Natural Toxicants Evaluation
Branch
CDM Camp Dresser & McKee
CERI Center for Environmental Research Information
CWA Clean Water Act
DDD Dichlorodiphenyldichloroethane
DDE Dichlorodiphenylethane
DDT Dichlorodiphenyltrichloroethane
D&M Distribution and marketing
Dt Acceptable daily dose
ECAO Environmental Criteria and Assessment Office
EPA U.S. Environmental Protection Agency
FDA U.S. Food and Drug Administration
HERL Health Effects Research Laboratory
HPLC High Performance Liquid Chromatography
IEMD Integrated Environmental Management Division
MERL Municipal Environmental Research Laboratory
Metro Municipality of Metropolitan Seattle
MGD Million Gallons per Day
MID Minimal Infectious Dose
MPRSA Marine Protection, Research, and Sanctuaries Act
N Nitrogen
NDV Newcastle Disease Virus
OEET Office of Environmental Engineering and Technology
OHEA Office of Health and Environmental Assessment
OHR Office of Health Research
O&M Operations and Maintenance
OPA Office of Policy Analysis
C-l
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LIST OF ACRONYMS AND ABBREVIATIONS (cont.)
ORD Office of Research and Development
ORPM Office of Research Program Management
OW Office of Water
OWPO Office of Water Program Operations
OWRS Office of Water Regulations and Standards
PAH Polycyclic Aromatic Hydrocarbon
PCB Polychlorinated Biphenyl
PFRP Processes to Further Reduce Pathogens
POTW Publically Owned Treatment Plant
ppb Parts per billion
ppm Parts per million
PSRP Processes to Significantly Reduce Pathogens
RNA Ribonucleic Acid
TCID50 Tissue Culture Infective Dose (in 50 per-
cent of cultures inoculated)
USDA U.S. Department of Agriculture
WAS Waste-Activated Sludge
WRD Wastewater Research Division
XAD A type of polydivinylbenzene polymer
C-2
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