NORTH CAROLINA --
Human Health Risk Evaluation of Land Application of Sewage Sludge/Biosolids
NC DHHS --Occupational and Environmental Epidemiology Branch
November 2005
Table 2 - Carcinogens (suspected and confirmed animal and human) that have been found in Land
Applied Sludges (2,32,34,35)
Aldrin, Arsenic, Benzene, Benzo(a)pyrene, Beryllium, Asbestos, Bis(2-ethylhexyl)phthalate, Benzo(a)anthracene,
Benzidine, Benzo(b)fluoranthene, Benzo(k)fluoranthene, Cadmium, Chlordane, Chloroform, Chrysene, Chromium VI,
Creosote, Chrysene, Dimethyl nitrosamine, Dioxin, DDD, DDE, DDT, Dibenzo(a,h)anthracene, Dieldrin, Dimethyl
nitrosamine, 1,2 Dichloroethane, 1,2,Dibromoethane, Heptachlor, Indeno(1,2,3-c,d)pyrene, Lead, Lindane, Methylene,
chloride, Nickel, PCBs, Toxaphene, Trichloroethylene, Tetrachloroethene, 1,1,2,2,Tetrachloroethane.
D. Concerns of adverse health effects in humans and animals from exposure to contaminants in land
applied biosolids
Tables 1-4 list the various contaminants that may be found in biosolids. These contaminants can impact humans
and animals through several routes of exposure (Table 5) and can have both acute and chronic effects based on
the type of exposure. Further, there are different interactions among these contaminants that may increase their
pathogenicity. While the DENR rules limit exposure of humans and animals to application sites it may still be
possible that humans and animals may be exposed to these various toxicants and pathogens. For example, Gibbs
et al (1997) have shown that conditions may exist for pathogen growth after application of Class B Biosolids. As a
result grazing animals may ingest and become infected by viable pathogens (11). There are anecdotal reports and
some published data that suggest that persons residing near application sites and workers exposed to biosolids
may experience adverse health effects such as respiratory and gastrointestinal symptoms as well as studies that did
not report adverse health effects. Symptoms reported in some of the residential studies include burning eyes,
cough, headaches, difficulty breathing, chest tightness, neurotoxicity, gastrointestinal effects, nausea and fatigue
(12-17). Studies of workers exposed to biosolids and sewage sludge have reported nasal irritation, gastrointestinal
complaints, diarrhea, headaches, sore throats, dizziness, respiratory problems, skin irritation and eye irritation (2,
18-31)
Occupational and Environmental Epidemiology Branch
November 2005
I. Introduction
The Occupational and Environmental Epidemiology Branch (OEEB) has received a number of complaints from
residents living adjacent to sites where treated sewage sludge (biosolids) has been applied to land. These
complaints are about odors as well as adverse health effects in persons living in close proximity to a land
application site. A recent source of complaints in North Carolina is from persons living near a land application site
along the Orange/Alamance County line. Residents living in this area have reported past health effects from land
applications of biosolids within 400 feet of their homes as well as nitrate contamination of private wells at a site in
Raleigh (1). In addition, the OEEB is aware of nitrate contaminated groundwater at sites where there has been
land application of biosolids as close as 400 feet from adjacent residences. As a result of these reports and health
complaints about land application of biosolids in general, OEEB has reviewed the scientific literature on land
application of biosolids, contacted experts involved in studying the potential health effects of land applied biosolids,
and has met with staff in the Division of Water Quality, in the North Carolina Department of Environment and Natural
Resources (DENR), about permit requirements for biosolids land application. This paper is a review of the
production and chemical and microbial composition of biosolids, rules governing land application of biosolids, and
some health effects that might result from land application of biosolids. This report will make some
recommendations about land application of biosolids based on the information in this report.
II. Background
A. Definition of terms
Biosolids and sewage sludge: Sewage sludge is defined in Chapter 40 Part 503 of the Code of Federal Regulations
(40 CFR Part 503) as “the solid, semi-solid, or liquid residue generated during the treatment of domestic sewage in
a treatment works. Biosolids are defined as sewage sludge that has been treated to meet standards for land
application under the Environmental Protection Agency’s Clean Water Act Part 503 or any other equivalent land
application standards (2).Residuals is the general term used in North Carolina for the waste material that is
obtained from the wastewater. The primary treatment of residual sludge is through the use of aerobic and
anaerobic processes. Biosolids are divided into two groups based on pathogen content and degree of treatment:
Class A biosolids: more vigorously treated; fewer living pathogens. There are no land use restrictions for applying
Class A biosolids.
Class B biosolids: less vigorously treated, but still with reduced level of pathogens compared to untreated sewage
sludge.. Many restrictions govern application of Class B biosolids (2). These will be detailed below.
Land application is a general term for spraying or spreading of residuals onto the surface of the land or injection or
incorporation below the top surface of the soil. The types of sub-surface land application include:
Incorporation- mixing of residuals with topsoil to a minimum depth of four inches by methods such as disking,
plowing, or rototilling Injection- subsurface application of liquid residuals to a depth of four to twelve inches
Agronomic rates are the rates at which waste can be applied to growing plants that
will meet the nutrient needs of the plants but does not overload the soil with nutrients or other constituents that will
adversely impact plant growth, soil quality or water quality.
B. Description of production and composition of biosolids
The primary end products of the wastewater treatment process are liquid effluent and sewage sludge. The
effluent can be disposed of by using one of several methods. These include discharge into surface waters.
Injection of untreated liquid effluent into groundwater is not allowed under North Carolina rules. Sewage sludge, or
biosolids, can be disposed of by incineration or placement in solid waste landfills, but the expense of these methods
limits their utility. Treated sewage sludge can also be applied to land. Land application has been desirable to some
landowners because the nutrient content of the sludge is seen as a substitute for the use of commercial fertilizers
and the organic matter in the sludge is good for the soil. As a result, land application of biosolids is the preferred
method of waste disposal for many North Carolina municipalities. However, biosolids contain many waste products
such as living pathogens (including bacteria and viruses), and organic and inorganic chemicals. These waste
products may be potential hazards when they are land applied. Further, depending on the method of treatment of
the residuals, there can be an objectionable odor of these land-applied biosolids. Therefore, the land application of
biosolids, while often the preferred method of disposal, has often been a controversial method due to the potential
for contamination of soil, crops, and water sources (2) and for the potential for objectionable odors.
The EPA sewage sludge rules, described below, were developed based on risk assessments done in the late 1980’
s and early 1990’s. These risk assessments evaluated the risk from chemicals and pathogens found in sewage
sludge. It was felt that the guidelines based on these risk assessments would be protective of public health. Based
on these risk assessments, EPA set guidelines for pathogen treatment procedures and methods to reduce the
amount of vector attraction. For land application, the EPA rules regulated nine inorganic metals (chemicals).
Levels of these regulated metals in biosolids were required to be below established, specific maximal concentrations
and for some uses, under monthly average concentrations. The regulated metals include arsenic, cadmium,
copper, lead, mercury, molybdenum, nickel, selenium, and zinc. Initially the EPA recommended that dioxins be
added to the list of regulated chemicals (3) but the EPA more recently determined that dioxins did not need to be on
the regulated list.
EPA determined that the following pathogen reduction processes could be used to generate Class A biosolids:
composting, heat drying, heat treatment, beta or gamma ray irradiation pasteurization, in addition to other
procedures. In comparison, while EPA rules for Class B biosolids require that levels of pathogens be reduced after
biosolids production and before land application, these reductions are not to the degree of reduction required for
Class A biosolids (2).
In North Carolina, the majority of biosolids that are land applied are Class B biosolids because the expense for the
treatment requirements for Class B is lower than that for Class A.
C. Description of pertinent rules and regulations governing biosolids disposal
1. Federal rules: Part 503 in Chapter 40 of the Code of Federal Regulations (CFR) by the Environmental
Protection Agency (EPA): This rule (termed “Part 503” in this paper) was published on March 22, 1993. It
established land application and other practices for sewage sludge in order to facilitate removal of waste products
from wastewater treatment facilities. Biosolids produced from sewage sludge must meet the standards of Part 503.
The Part 503 rules require this treatment be at a level that ensures protection of public health upon release of the
biosolids to the environment 2.
2. Current and proposed North Carolina Rules for Land Application of Sludge (4):
The Division of Water Quality in the North Carolina Department of Environment and Natural Resources (DENR) is
the state agency responsible for evaluating and permitting the land application of biosolids and other wastewater
residuals. This includes the establishment of relevant rules which govern the evaluation and permitting of land
application of biosolids. DENR is also responsible for investigating citizen complaints involving land application of
biosolids. DENR utilizes the Part 503 rules as the basis for establishing North Carolina rules. The North Carolina
rules include required “setbacks” for land application sites. These setbacks regulate the minimum distance land
application is allowed from various natural and man-made features such as residences and water sources. North
Carolina rules that have been established by DENR are stricter than the Part 503 rules (4). For example, the North
Carolina rules require larger setbacks than required by the federal rules. The federal rules (503.14 c) require a 10
meter (32.8 feet) setback from surface waters while the state rules (15A NCAC 02T.1109) require a100 foot setback
from surface waters.
DENR has established a permitting process to approve the land application of sewage sludge. The rules require a
“site assessment” which includes the following:
Soil scientist evaluation including an evaluation of water table depth
Topography map
Watershed determination
Buffer map which is often “field verified” by DENR
The permit includes allowed “setbacks,” control of pathogens/vector attraction and the nine inorganic chemicals
regulated by federal rules. In addition, the permit requires an additional level of control of hazardous materials.
This is accomplished by the use of processes such as chemical leaching tests, reactivity tests, corrosivity tests, and
ignitability tests.
In general, DENR rules will not allow surface land application of bulk liquid residuals if the proposed site has a slope
greater than 10%, and will not allow injection or incorporation of bulk liquid residuals if the slope of the land is
greater than 18%. Variance requests can be made and approved in some cases. Under North Carolina rules, site-
specific agronomic rate calculations by DENR are not required for a site to be permitted. Instead, agronomic rates
are calculated based on geographic specific rates that are specific for a region or type of soil in an area, but are
not based on the specific site on which residuals are proposed to be applied. The proposed rules provide more
specific calculations for a particular site than do the existing rules but still will not require site specific agronomic rate
calculations at all proposed sites.
As noted in the Background Section, there are no restrictions in Part 503 for the land application of Class A
biosolids. In contrast, the following proposed North Carolina rules govern the land application of Class B biosolids:
a. Public access to land-applied sites “with a high potential for public exposure” is prohibited for one year following
application. This does not apply to farm workers. Although agricultural land is private property and is not
considered to have a high likelihood of public access, these restrictions still apply.
b. Restrictions on growing and harvesting of crops vary by the type of crop.
Grazing by animals on crops in fields where land application has occurred is prohibited for 30 days following
application.
Application is allowed on agricultural and forest land, but is prohibited on public lawns or gardens.
The following setback rules have been established or are being proposed by DENR:
a. Residences, churches and schools: Land application of biosolids must be at a minimum of 400 feet if biosolids
are “surface applied.” If biosolids are applied by injection/incorporation then it must be at a minimum of 200 feet
from the structure.
b. Property lines: Minimum distance from a property line is 50 feet for surface application by vehicle, 150 feet for
surface application by irrigation, and 50 feet by injection/incorporation methods of application.
Drinking water sources: Minimum distance from wells used for drinking water is 100 feet for both surface and
subsurface land application.
It is not known how these setback distances were determined. Discussions with DENR staff indicate that the basis
for these setback distances is not generally known as they were established some time in the past. It is important
that these distances be determined using appropriate research design and data in order to ensure that
contaminants will not leach into water supplies or adversely impact the health of surrounding residents. OEEB feels
that this data should be developed to determine if the allowed setback distances are appropriate.
The permitting process may require monitoring wells at dedicated sites but not at nondedicated sites. The use of
monitoring wells would indicate whether contaminants are leaching into groundwater and are a quality control
method to ensure that contaminants are not threatening the public health.
There are no specific restrictions in the state permit rules on frequency of land application at a site. In some rare
cases, there may be seasonal restrictions on frequency of application. However, in most instances, the frequency
of application will be based on the needs of the biosolids producer to remove sewage sludge from their facility and
the needs of the landowner to use the sewage sludge as fertilizer for their crops. The use of agronomic rates and
frequency of application limits which allow agronomic rate calculations for sites to be achieved may not parallel the
needs to land apply discussed above for the sewage sludge producer and land applicator. As a result, protection
of public health may not be achieved under the current EPA and state rules.
3. Permitting procedures: A water treatment facility desiring to apply biosolids first sends an application to the
central DENR office with a copy to the regional DENR office. DENR reviews the application, and may send
comments back to the applicant. DENR may choose to issue or deny a permit as a whole, or may permit or deny
portions of the permit.
Issues needing review and OEEB recommendations
Staff in OEEB feel the following issues should be addressed in the permitting of land application of biosolids due
to its concerns that the current EPA and state rules regarding land application of biosolids may be posing increased
health risks to residents adjacent to these sites in North Carolina.
Siting of biosolids application sites, including setbacks and proximity issues
Amounts of biosolids that can be applied. This includes the issue of “agronomic rates.”
Concerns of odor from biosolids
Concerns of exposure and adverse health effects from biosolids contaminants in humans and animals
A. Siting of biosolids application sites
As noted above, DENR evaluates proposed land application sites from a number of standpoints. DENR does a
site evaluation of each proposed application site and considers many features of the site in it’s assessment, but
there are few specified topographical features that will lead to a disqualification of a site. For example, while slope
is considered in the evaluation of a site for application of liquid residuals (see above) there are no restrictions on
slope for the application of more solid materials. The proposed rules do not specify what topographical features,
such as surface water distance from the proposed site that would lead to disqualification of a site because of the
potential for contamination of these topographical features. OEEB feels that it is important to specify how
topographical features would be considered in the site assessment and develop criteria for acceptable and
unacceptable topographical features.
The proposed state rules include siting criteria that include many allowable “setbacks” from various topographical
features such as property lines and drinking water wells. As mentioned earlier, the setbacks required by state rules
are greater than those required by federal rules. It is not known how these distances were determined, and
discussions with DENR staff indicate that this is not well known. These distances seem to be minimal, and it is not
known whether there are any data to support these setback distances. However, there is some published
epidemiologic evidence that suggests that these setback distances may not be adequate to eliminate the risk to
public health (1,5-8) OEEB feels that there should be research to determine if these setback distances are
adequate to protect both water supplies and public health. This research should include monitoring well data for
land application sites.
There is evidence that nitrate contamination at levels that might pose an increased health risk has occurred in
drinking water wells near land application sites. In one instance nitrate contamination of 18 wells located as far as
800 feet from the City of Raleigh Water Treatment Plant application site has been documented by DENR (1) at
levels that exceed the EPA nitrate standard of ten parts per million (ppm). Hydrogeological investigations by DENR
(1) have determined that the frequency of land application of biosolids that caused an exceedance of the
agronomic rates for this site occurred causing residential private well and groundwater contamination. Nearby
private well contamination may have been associated with this application. In another case, groundwater near a
biosolids application site in Rutherford County was contaminated with nitrates at levels greater than the EPA
standard of ten ppm. The existence of this contamination suggests that land application of biosolids may have been
responsible for contaminating groundwater and residential private wells. DENR has documented nitrate
groundwater contamination from a spray field in Robeson County that caused nitrate contamination of residential
wells in exceedance of the 10 ppm EPA limit as far as 1400 feet from the edge of the land application site (8). This
data indicates that land application of biosolids under the current EPA and state rules can result in groundwater
and private well contamination of nitrates that has the potential to travel as far as 1400 feet from the edge of a land
application site. The extent of groundwater contamination at biosolids land application sites may never be known
because there are no current requirements for monitoring wells in the state rules and no frequency requirements
that would assure the achievement of agronomic rates for all specific biosolids land application sites.
Because of these instances of groundwater contamination and the public health risks that might occur from
contamination of drinking water wells, OEEB feels that a monitoring program should be in place to determine if land
application sites are causing nitrate contamination of water sources. This program should include monitoring wells
around the perimeter of dedicated and selected non-dedicated land application sites in order to detect possible
groundwater contamination. The monitoring wells should be located at one-half of the required setback distance
away from the boundary of the dedicated land application site and between the land application site and the
location of drinking water wells. Until more data are available to scientifically determine appropriate setbacks, the
currently proposed allowable setbacks should be doubled. This will take into consideration the OEEB’s concern
that nitrate groundwater contamination may extend beyond the current setbacks and will decrease the likelihood of
groundwater contamination and adverse effects on public health.
B. Amounts of biosolids that can be applied, including the issue of “agronomic rates”
The proposed DENR rules specify criteria to limit the concentration of the nine “regulated” inorganic chemicals, and
set forth criteria to require “pathogen reduction.” However, there are no specific limitations on amount of biosolids
that can be applied to a particular site. There is some evidence in the literature (9) that suggests that applied
contaminants may accumulate and increase in concentration over time. This is not universally accepted, as the
Division of Solid and Hazardous Materials within the New York State Department of Environmental Conservation has
argued against the findings of Harrison (10). Gibbs et al (1997) showed that pathogens are able to grow and
accumulate under favorable conditions in soil and that soils could become pathogen-rich over time. They also
showed that this was true for chemicals that can bind to soil and then slowly leach into groundwater (11).
Agronomic rates are an important consideration in determining the allowable amount and frequency of biosolids
application (1,2, 4-8). During the 1990’s agronomic rates were used by the hog industry to justify safe levels of
waste disposal, but the discovery of nitrate contamination of groundwater near several hog waste spray fields
raised questions about the usefulness of agronomic rates to protect groundwater quality in these circumstances,
especially as they related to the lack of control over the frequency of land application (5-8). However, it is logical
that plants would have a maximal rate for uptake of nutrients and agronomic rates are a means to account for this.
OEEB feels that it is important to carefully determine standardized site specific agronomic rate calculations for all
biosolids application sites that have a frequency requirement as an added safeguard to protect against water
contamination. A requirement for monitoring wells at all land application sites would be a means of assuring that
groundwater is protected from contamination.
As discussed above, an additional consideration in whether land application at a particular site is not in excess of its
capacity to absorb the waste materials is the frequency of biosolids application. OEEB feels that this should be
evaluated for each site as an added safeguard to protect against water contamination. An allowable application
frequency should be based on measurements of contaminants in the soil and by the system of monitoring wells
discussed above.
C. Concerns of odor
Objectionable odors can be associated with application of biosolids (2). In fact, OEEB has received complaints
about odors from residents near land application sites. Odors are logically a part of these residuals. The nature
and severity of the odors can be the result of the type of treatment of residuals. Aerobic treatment is usually
associated with the least objectionable odors, while anaerobic treatment of residuals that are allowed to be treated
for an extended length of time, can be associated with a more disagreeable odor (2).
Since application of biosolids can occur in relatively close proximity to residents, OEEB feels that it is important to
take whatever steps are necessary to minimize or eliminate odors from land applied biosolids. These should follow
established “best practices.” These could include measures such as requiring aerobic treatment of residuals if
these are to be applied within a pre-determined distance from a residence. These measures could also include
establishing greater setbacks than currently exist to provide an additional buffer against the odors. OEEB
encourages more research into the odor issue so that appropriate measures can be taken to minimize or eliminate
odor from land applied biosolids. OEEB encourages the use of any developed guidelines be included in any
established rules so that odors experienced by residents near these application sites are minimized or eliminated.
D. Concerns of adverse health effects in humans and animals from exposure to contaminants in land
applied biosolids
Tables 1-4 list the various contaminants that may be found in biosolids. These contaminants can impact humans
and animals through several routes of exposure (Table 5) and can have both acute and chronic effects based on
the type of exposure. Further, there are different interactions among these contaminants that may increase their
pathogenicity. While the DENR rules limit exposure of humans and animals to application sites it may still be
possible that humans and animals may be exposed to these various toxicants and pathogens. For example, Gibbs
et al (1997) have shown that conditions may exist for pathogen growth after application of Class B Biosolids. As a
result grazing animals may ingest and become infected by viable pathogens (11). There are anecdotal reports and
some published data that suggest that persons residing near application sites and workers exposed to biosolids
may experience adverse health effects such as respiratory and gastrointestinal symptoms as well as studies that did
not report adverse health effects. Symptoms reported in some of the residential studies include burning eyes,
cough, headaches, difficulty breathing, chest tightness, neurotoxicity, gastrointestinal effects, nausea and fatigue
(12-17). Studies of workers exposed to biosolids and sewage sludge have reported nasal irritation, gastrointestinal
complaints, diarrhea, headaches, sore throats, dizziness, respiratory problems, skin irritation and eye irritation (2,
18-31).
Based on these studies, OEEB feels that a surveillance program of humans living near application sites should be
developed to determine if there are adverse health effects in humans and animals as a result of biosolids
application. This surveillance program should be combined with a well-monitoring program that will determine if
contaminants are leaching into groundwater as well as amended setback distances that account for the distances of
concern for nitrate groundwater contamination. OEEB will work with DENR in developing a health surveillance plan
and looking for funds for supporting the surveillance program.
Table 1 - Compounds Detected in Biosolids 2, 32,33)
SUBSTANCE
Halogenated volatiles
1,4-Dichlorobenzene
cis-1,2-Dichloroethylene
Dichloromethane
Tetrachloroethylene
Non-halogenated volatiles
Toluene
Meta- and para-xylene
Ortho-xylene
Total xylenes (calculated)
Volatile petroleum hydrocarbons
Base-neutral extractables
Benzyl butyl phthalate
Bis(2-ethylhexyl) phthalate
Di-n-butyl phthalate
Diethyl phthalate
Dimethyl phthalate
Polycyclic aromatic hydrocarbons
Acenaphthene
Acenaphthylene
Anthracene
Benz(a)anthracene
Benzo(a)pyrene
Benzo(b)fluoranthene
Benzo(g,h,i)perylene
Benzo(k)fluoranthene
Fluoranthene
Fluorene
Indeno(1,2,3-c,d)pyrene
Naphthalene
Phenanthrene
Pyrene
Chlorinated and nonchlorinated phenolics
4-Chloro-3-methylphenol
2,4 and 2,5 Dichlorophenol
3,4,5-Trichlorophenol
2,3,4,5-Tetrachlorophenol
2,3,4,6-Tetrachlorophenol
Pentachlorophenol
m-Cresol
o-Cresol
p-Cresol
2,4-Dimethylphenol
2-Nitrophenol
4-Nitrophenol
Phenol
Extractables
Light extractable petroleum
Hydrocarbons (LEPHs)
Heavy extractable petroleum
Hydrocarbons (HEPHs)
Dioxins
2,3,7,8-TCDD
TCDD - Total
1,2,3,7,8-PCDD
PCDD - Total
1,2,3,4,7,8-HexCDD
1,2,3,6,7,8-HexCDD
1,2,3,7,8,9-HexCDD
HexCDD - Total
1,2,3,4,6,7,8-HCDD
HCDD - Total
OCDD - Total
Furans
2,3,7,8-TCDF
TCDF - Total
1,2,3,7,8-PCDF
2,3,4,7,8-PCDF
PCDF - Total
1,2,3,4,7,8-HexCDF
1,2,3,6,7,8-HexCDF
2,3,4,6,7,8-HexCDF
1,2,3,4,7,8,9-HexCDF
HexCDF - Total
1,2,3,4,6,7,8-HCDF
1,2,3,4,7,8,9-HCDF
HCDF - Total
OCDF - Total
PCDDF’s TEQs
2,3,7,8-TCDD TEQs
2,3,7,8-TCDD TEQs
Metals/Inorganic Chemicals
Arsenic
Barium
Cadmium
Chromium
Cobalt
Copper
Lead
Molybdenum
Nickel
Selenium
Silver
Tin
Zinc
Table 2 - Carcinogens (suspected and confirmed animal and human) that have been found in Land
Applied Sludges (2,32,34,35)
Aldrin
Arsenic
Benzene
Benzo(a)pyrene
Beryllium
Asbestos
Bis(2-ethylhexyl)phthalate
Benzo(a)anthracene
Benzidine
Benzo(b)fluoranthene
Benzo(k)fluoranthene
Cadmium
Chlordane
Chloroform
Chrysene
Chromium VI
Creosote
Chrysene
Dimethyl nitrosamine
Dioxin
DDD
DDE
DDT
Dibenzo(a,h)anthracene
Dieldrin
Dimethyl nitrosamine
1,2 Dichloroethane
1,2,Dibromoethane
Heptachlor
Indeno(1,2,3-c,d)pyrene
Lead
Lindane
Methylene chloride
Nickel
PCBs
Toxaphene
Trichloroethylene
Tetrachloroethene
1,1,2,2,Tetrachloroethane
Table 3 - Odorants Found in Biosolids (2,34,36,37)
Class Compounda Formulaa Charactera
Sulfurous Hydrogen sulfide H2S Rotten eggs
Dimethyl sulfide (CH3)2S Decayed vegetables, garlic
Diphenyl sulfide (C6H5)2S Unpleasant, burnt rubber
Carbon disulfide CS2 Decayed vegetables
Dimethyl disulfide (CH3)2S2 Putrification
Methyl mercaptan CH3SH Decayed cabbage, garlic
Ethyl mercaptan C2H5SH Decayed cabbage
Propyl mercaptan C3H7SH Unpleasant
Allyl mercaptan CH2CHCH2SH Garlic
Benzyl mercaptan C6H5CH2SH Garlic
Thiocresol CH3C6H4SH Skunk, rancid
Nitrogenous Ammonia NH3 Sharp, pungent
Methylamine CH3NH2 Fishy
Dimethylamine (CH3)2NH Fishy
Trimethylamine (CH3)3N Fishy, ammoniacal
Ethylamine C2H5NH2 Ammoniacal
Triethylamine (C2H5)3N
Pyridine C6H5N Disagreeable, irritating
Indole C8H6NH Fecal, nauseating
Scatole or Skatole C9H8NH Fecal, nauseating
Acids Acetic (ethanoic) CH3COOH Disagreeable, irritating
Butyric (butanoic) C3H7COOH Rancid, sweaty
Aldehydes
& ketones Acetaldehyde CH3CHO Fruit, apple
Table 4 - Principle Pathogens of Concern in Biosolids (2,38-48)
Organism Disease/Symptoms
Bacteria
Salmonella sp. Salmonellosis (food poisoning), typhoid fever
Shigella sp. Bacillary dysentery
Yersinia sp. Acute gastroenteritis (including diarrhea, abdominal pain)
Vibrio cholerae Cholera
Campylobacter jejuni Gastroenteritis
Escherichia coli Gastroenteritis (pathogenic strains)
Enteric Viruses
Hepatitis A virus & E Infectious hepatitis
Norwalk & Norwalk-like
Viruses Epidemic gastroenteritis with severe diarrhea
Rotaviruses Acute gastroenteritis with severe diarrhea
Enteroviruses
Polioviruses Poliomyelitis
Coxsackieviruses Meningitis, pneumonia, hepatitis, fever, cold-like symptoms, etc.
Echoviruses Meningitis, encephalitis, fever, cold-like symptoms,
diarrhea, etc.
Reovirus Respiratory infections, gastroenteritis
Astroviruses Epidemic gastroenteritis
Caliciviruses Epidemic gastroenteritis
Protozoa
Cryptosporidium Gastroenteritis
Entamoeba histolytica Acute enteritis
Giardia lamblia Giardiasis (including diarrhea, abdominal cramps, weight loss)
Balantidium coli Diarrhea and dysentery
Toxoplasma gondii Toxoplasmosis
Helminth Worms
Ascaris lumbricoides Digestive and nutritional disturbances, abdominal pain, vomiting, restlessness
Ascaris suum May produce symptoms such as coughing, chest pain, and fever
Trichuris trichiura Abdominal pain, diarrhea, anemia, weight loss
Toxocara canis Fever, abdominal discomfort, muscle aches, neurological symptoms
Taenia saginata Nervousness, insomnia, anorexia, abdominal pain, digestive disturbances
Taenia solium Nervousness, insomnia, anorexia, abdominal pain, digestive disturbances
Necator americanus Hookworm disease
Hymenolepis nana Taeniasis
Table 5 - Pathways of Exposure for Class B Biosolids and associated regulatory controls(2)
Pathways Part 503 Required Site Restriction
Skin exposure from handling soil
from fields where No public access* to application sites until
sewage sludge has been applied at least 1 year after Class B biosolids
application.
Skin exposure from handling soil
or food from home Class B biosolids may not be applied on
gardens where sewage sludge has home gardens.
been applied
Inhaling dust** No public access to application sites until at
least 1 year after Class B biosolids
application.
Skin or respiratory exposure from
walking through fields where No public access to fields until at least 1
sewage sludge has been year after Class B biosolids application.
applied**
Consumption of crops from fields Site restrictions which prevent the
on which sewage sludge has been harvesting of crops until environmental
applied attenuation has taken place.
Consumption of milk or animal No animal grazing for 30 days after Class
products from animals grazed on B biosolids have been applied.
fields where sewage sludge has
been applied.
Ingestion of water contaminated Class B biosolids may not be applied
by runoff from fields where sewage within 10 meters of any waters in order to
sludge has been applied prevent runoff from biosolids amended land
from affecting surface water.
Ingestion of inadequately cooked Class B biosolids may not be applied with
fish from water contaminated by 10 meters of any waters in order to prevent
runoff from fields where sewage runoff from biosolids amended land from
sludge has been applied affecting surface water.
Contact with vectors which have All land applied biosolids must meet one of
been in contact with sewage the Vector Attraction Reduction options (see
sludge Chapter 8).
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