EPA/600/R-07/055
September 2007
Proceedings of the Biosolids Exposure
Measurement Workshop
National Exposure Research Laboratory
Office of Research and Development
U. S. Environmental Protection Agency
26 W. Martin Luther King Drive
Cincinnati, OH 45268
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Proceedings of the Biosolids Exposure
Measurement Workshop
Edited by
Michael W. Ware, National Exposure Research Laboratory
Ann C. Grimm, National Exposure Research Laboratory
Workshop Steering Committee
G. Shay Fout, National Exposure Research Laboratory
Ann C. Grimm, National Exposure Research Laboratory
Bruce Mintz, National Exposure Research Laboratory
James E. Smith, National Risk Management Research Laboratory
Laurel J. Staley, National Risk Management Research Laboratory
Michael W. Ware, National Exposure Research Laboratory
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Abstract
Sludges are generated during the processing of wastewater. These sludges are
further treated, primarily to reduce the concentration of pathogens, to produce
biosolids which are then beneficially used on land. In the United States, the
Environmental Protection Agency regulates biosolids through the 1993 40 CFR
Part 503 regulations. A 2002 National Academy of Sciences-National Research
Council report, "Biosolids Applied to Land: Advancing Standards and Practices,"
concluded that additional scientific work was needed to reduce uncertainty about
human health effects from exposure to biosolids. The final Agency response to
this report was published in the Federal Register in 2003. The response included
an action plan with 14 projects related to the treatment and disposal of biosolids.
One of these projects was to conduct a Biosolids Exposure Measurement
Workshop. This workshop was held March 16-17, 2006, at the Andrew W.
Breidenbach Environmental Research Center, Cincinnati, OH.
This document is a summary of the workshop. It describes presentations given
by 16 experts on issues relevant to measuring human exposure to biosolids
contaminants and outlines the topics covered during a panel discussion session.
It concludes with a list of research needs that, if met, will enable the
environmental community to better evaluate human exposure to biosolids
contaminants. In the long-run, the goal of this workshop is to help enable the
Agency to better assess the risk associated with the land application of biosolids.
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Notices
The views expressed in this Summary Report are those of the individual authors
and may not necessarily reflect the views and policies of the United States
Environmental Protection Agency (USEPA). Sections prepared by Agency
scientists have been reviewed in accordance with USEPA's peer and
administrative review policies and approved for presentation and publication.
Mention of trade names or commercial products does not constitute endorsement
or recommendation by USEPA for use.
in
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Contents
Abstract ii
Notices iii
Acronyms and Abbreviations vi
Introduction 1
Workshop Background and Objectives
Bruce Mintz 1
Land Application and Sludge Treatment
James E. Smith 2
Protocols for the Timely Investigation of Potential Health Incidents Associated with Biosolids Land Application
Alfred P. Dufour 2
Community Perspective of Biosolids Land Application
Maureen Reilly 2
Current Exposure Measurement Methods and Risk Assessment 4
Multi-media Sampling at a Biosolids Land Application Test Site
Eric A. Foote 4
Pathogen Risk Assessment for Biosolids: Recent Developments
Jeffrey A. Seller 5
Sludge Fate and Transport 6
Analyzing Biosolids for Microorganisms to Achieve Regulatory Compliance
MarkC. Meckes 6
Fate and Transport Models
Charles P. Gerba 6
Dermal Exposure 7
Non-invasive Assessment of Dermal Exposure
Karla D. Thrall 7
Odors and Irritants 8
Odor, Irritation and Health Symptoms from Biosolids
Pamela H. Dalton 8
Odor Measurements and Impacts from an Experimental Biosolids Land Application Site
Robert H. Forbes, Jr 8
Particulates 9
Airborne Particulates: Technologies and Measurement Issues
Patricia D. Millner 9
Pathogens and Endotoxins 10
Biomarkers of Viral Exposure
G. Shay Fout 10
Community and Occupational Risk from Bioaerosols During Land Application of Biosolids
Ian L. Pepper 10
Improving the Efficiency of an Impinger for Collecting Bacteria During a Biosolids Application Field Study
Edwin F. Barth 11
Endotoxins
Nancy C. Burton 11
Occupational Exposure Assessments at WWTPs
Nancy C. Burton 11
IV
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Contents (continued)
Panel Discussion Session 13
Bibliography 15
Appendices
A Biosolids Exposure Measurement Workshop Agenda 16
B Participant List 18
C Update on Incident Response Project 24
D Technical Papers 25
D-1 Non-Invasive Assessment of Dermal Exposure 26
D-2 Odor, Irritation, and Health Symptoms from Biosolids Land Applications 30
D-3 Detection and Measurement of Odor, Ammonia, and Hydrogen Sulfide Emissions as part of USEPA
Biosolids Land Application Research Project 34
D-4 Community and Occupational Risk from Bioaerosols during Land Application of Biosolids 37
D-5 Lessons Learned Regarding the Use of an Impinger for Collecting Airborne Bacteria during a
Biosolids Application Field Study 40
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Acronyms and Abbreviations
AGI All glass impinger
CDC Centers for Disease Control and Prevention
CFR Code of Federal Regulation
D/T Dilution/threshold
ELISA Enzyme-Linked Immunosorbent Assay
FT Foot
FTIR Fourier Transform Infrared Spectroscopy
HPC Heterotrophic plate counts
M Meter
MIN Minute
MRA Microbial risk assessment
MAS National Academy of Sciences
NCEA National Center for Environmental Assessment (USEPA)
NOT National Decontamination Team (USEPA)
NERL National Exposure Research Laboratory (USEPA)
NHEERL National Health and Environmental Effects Research Laboratory (USEPA)
NIOSH National Institute for Occupational Safety and Health
NRC National Research Council
NRMRL National Risk Management Research Laboratory (USEPA)
OW Office of Water (USEPA)
OW-OWM Office of Water Office of Wastewater Management (USEPA)
OW-OST Office of Water Office of Science and Technology (USEPA)
PBPK Physiologically based pharmacokinetic
PCR Polymerase chain reaction
PI Principal Investigator
PM2.5 Particulate matter 2.5 urn or smaller
PPM Parts per million
PPMV Parts per million by volume
QA Quality assurance
QAPP Quality assurance project plan
QC Quality control
RFP Request for proposal
SEC Second
USDA United States Department of Agriculture
USEPA United States Environmental Protection Agency
UV Ultraviolet
VOC Volatile organic compound
VIC Volatile inorganic compound
WERF Water Environment Research Foundation
WWTP Wastewater treatment plant
VI
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Introduction
The pathogen and vector attraction reduction of treated
sludge is regulated by the U.S. Environmental Protection
Agency (USEPA) through the Subpart D requirements of
the 40 CFR Part 503 Rule (USEPA, 1993). This
regulation was promulgated in 1993 under the authority
of the Clean Water Act. A National Academy of
Sciences (NAS)-National Research Council (NRC) 2002
report entitled, "Biosolids Applied to Land: Advancing
Standards and Practices," noted that there is a limited
amount of information on the effect of biosolids land
application on individuals living or working near such
sites. Although the report states that there is no
documented scientific evidence that Part 503 regulations
have failed to protect public health, it concluded that
additional scientific work is needed to reduce uncertainty
about the potential for adverse human health effects
from exposure to biosolids. The research needed
includes gathering epidemiological data, investigating
allegations of health incidents and conducting additional
exposure and risk studies in community populations.
The report suggested conducting preplanned exposure
assessment studies to characterize the effect of biosolid
exposure on the community, to identify chemicals and
microorganisms in collected field samples, and to
measure endotoxin exposure (bacterial cell wall
constituents).
These research priorities were further delineated by
participants in the USEPA-Water Environment Research
Foundation (WERF) Biosolids Research Summit in 2003
(WERF, 2004). Several high-priority research needs
were identified, including: (a) the development and
deployment of a rapid incident response process to
evaluate possible health effects associated with a
biosolids land application; (b) the characterization of
bioaerosols associated with the land application of
biosolids; and (c) the identification of the odor
compounds emitted by sludge in the various stages from
generation to end use, and the specification of their
sensory potencies and mechanisms of generation and
release.
The Agency described its action plan for responding to
the NRC report in the Federal Register notice entitled
"Final Agency Response to the National Research
Council Report on Biosolids Applied to Land and the
Results of EPA's Review of Existing Sewage Sludge
Regulations" (USEPA, 2003). The plan included a list of
14 projects, with the goal being the strengthening of the
technical basis for sewage sludge use and disposal
regulations. One of these projects was to conduct a
workshop that would examine issues relating to the
measurement of exposures associated with biosolids.
To address this need, the USEPA hosted a Biosolids
Exposure Measurement Workshop on March 16-17,
2006 at the Andrew W. Breidenbach Environmental
Research Center in Cincinnati, OH. Seventy-seven
people, including researchers from government and
academia, regional sludge coordinators, state sludge
coordinators, and other stakeholders, participated in the
event. This report provides a summary of the workshop,
which included presentations by 16 experts, followed by
a panel discussion session. The primary focus of the
workshop was to identify current measurement tools and
to prioritize research on human health effects related to
land application of biosolids. The workshop agenda and
list of participants are provided in Appendices A and B,
respectively. Appendix C is an update on the status of
the WERF incident response project. Five technical
proceedings papers are found in Appendix D.
Workshop Background and Objectives
Bruce Mintz
Mr. Mintz, an Assistant Laboratory Director for USEPA's
National Exposure Research Laboratory (NERL),
opened the workshop by discussing its background and
objectives. Public concern about this issue is of major
importance, particularly when it is unclear whether
reported incidences of adverse human health effects are
attributable to the land application of biosolids. The
NRC Report (2002) found that "there is a lack of
exposure and health information on populations exposed
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to biosolids," and recommended that "EPA promote and
support response investigations, targeted exposure
surveillance studies, and a few well-designed
epidemiological investigations of exposed populations."
Measuring exposure to biosolids is very complex
because of the number of possible contaminants and
exposure pathways. The Section 503 Rules identified
14 exposure pathways related to land application of
biosolids. This workshop focused primarily on the
inhalation and dermal absorption pathways because
most of the published complaints describe symptoms
that would be associated with these pathways. The
objectives of the group panel discussion were to identify
protocols for exposure measurement and modeling and
to recommend research priorities. The group tried to
reach a consensus on priority contaminants, sampling
procedures and frequency, methods of analysis, and
fate and transport measurement and modeling.
Land Application and Sludge Treatment
James E. Smith
Dr. Smith, with USEPA's National Risk Management
Research Laboratory (NRMRL), discussed biosolids and
issues associated with land application. Wastewater
treatment plants (WWTP) are designed to remove
sewage contaminants, resulting in a clean effluent which
is discharged into the environment. These contaminants
are concentrated in sludge which can be treated to form
biosolids that are then beneficially used on land.
Approximately 60% of WWTPs treat and land apply
biosolids. This accounts for 40% of the total amount of
sludge produced in the U.S. Collectively, this provides
more than four million dry tons of material per year for
land application. [Note: additional data, not available at
the time of the workshop, can be found at:
www.nebiosolids.org] Biosolids applied to land must
meet federal and state disinfection, vector attraction
reduction, and chemical concentration requirements
(primarily metals) for protecting the public health. The
minimal metal concentrations are largely achieved by
pretreating industrial wastes. The Section 503 Rule
approach for public health protection uses multiple
barriers, including disinfection and stabilization (vector
attraction control) to reduce pathogens below the
detection limit (Class A). If indicator organisms are
present in sufficient densities, the biosolids are
considered Class B and land use restrictions are then
imposed. These restrictions are designed to allow for
natural decay of the pathogens.
More information would aid in determining the best way
to use biosolids. Some issues to address include
studying the aerosols and dusts generated as the
material dries, identifying the fate of pathogens, and
verifying the effectiveness of Class B disinfection
processes in inactivating pathogens. In addition, some
biosolid treatment and application processes tend to
emit odors and aerosols and so it would be helpful to
determine if the public concerns about land applied
biosolids are due more to aesthetic issues or to human
health effects.
Protocols for the Timely Investigation of
Potential Health Incidents Associated with
Biosolids Land Application
Alfred P. Dufour
Dr. Dufour, with USEPA's NERL, discussed a
December, 2004 WERF workshop on rapid incident
response to health complaints from land application of
biosolids. Participants in the meeting developed a
request for proposal (RFP), based on input about
previous cases of reported health effects from the
perspective of those affected.
The objectives of the RFP will be addressed in three
phases. Phase 1 will involve the development of a
protocol for rapid incident response. This will be
achieved by: reviewing previous incidents, collecting
information on all adverse environmental outcomes,
developing a data collection/investigative instrument,
consulting with states about conducting investigations,
providing investigation guidance, and communicating
with health practitioners. In Phase 2, the protocol will be
refined after pilot testing at three localities. After the
protocol is optimized, recommendations will be made to
WERF on how to roll out the protocol nationwide. In
Phase 3, a database of biosolids-related investigations
will be developed. In addition, guidance will be provided
on the communication of the protocol to the public
through community dialogs and other mechanisms.
An update on the Rapid Incident Response Project is
provided in Appendix C.
Community Perspective of Biosolids Land
Application
Maureen Reilly
Ms. Maureen Reilly, with Sludgewatch, outlined her
concerns about biosolids policies and practices from her
perspective as a member of a community in which
biosolids have been land applied. In her view:
• The health, water supplies, quality of life, and
property values of rural communities have been
compromised by land application of biosolids.
• There is not an effective mechanism for the
public to express their concerns about adverse
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health effects that they believe to be caused by
biosolids applications.
The WERF rapid incident response project,
which will formulate a mechanism to respond to
complaints, has been delayed too long.
The oversight of land application is complicated
by the multiple regulations and governmental
authorities (federal, state, county, and
municipal).
The 40 CFR Part 503 regulations need rigorous
review.
Since the 40 CFR Part 503 regulations were
promulgated they have been made more lenient
and are enforced less aggressively.
There has not been adequate research on
pathogens or on the synergistic effects of
contaminants that may be in sewage sludge.
There is the perception that the USEPA is both
the regulator and the chief promoter of land
application.
Ms. Reilly made several suggestions that would help
address her concerns. First, she suggested that a
permitting process would allow for better compliance
monitoring and should be implemented. Currently, the
40 CFR Part 503 regulations are self-implementing and
no written permit is required. Second, Ms. Reilly
suggested the risks from land application can be
reduced by separating medical and industrial wastes
from the general waste stream, and by monitoring
application sites for contaminants. Finally, she
suggested that complaints should be systematically
recorded, responded to, and if required, investigated. In
conclusion, in her view, the small amount of money
saved by land application is offset by increased illness,
hospital costs, and contamination of soil and water.
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Current Exposure Measurement Methods and Risk Assessment
Multi-media Sampling at a Biosolids Land
Application Test Site
Eric A. Foote
Mr. Foote, with Battelle, reported on an approach utilized
for onsite sampling at a biosolids land application site.
The research was a collaboration of the USEPA, the US
Department of Agriculture (USDA), the North Carolina
Department of Agriculture, Battelle, and other supporting
groups, agencies, and organizations. This field study,
which is one of the projects described in the December
2003 USEPA action plan, was conducted in 2004 on a
two-acre plot of grass pasture in Salisbury, North
Carolina. This site was selected because it had not
received previous biosolids applications. Air and soil
sampling were conducted prior to and during the surface
application of anaerobically digested and dewatered
biosolids, and some sampling continued for several
months.
The goals of this research study were to develop a multi-
media sampling approach for airborne and soil-bound
contaminants resulting from the land application of
biosolids, and to optimize this sampling approach for use
in future studies. The study measured air emissions and
their short-range transport, and soil microbial
concentrations at and around the test site, with a focus
on selected constituents including particulates
(endotoxins), microorganisms (bacteria, fungi, and
viruses), and volatile compounds (including
malodorants). Prior to application, the biosolids were
analyzed for these compounds. Biomass loadings,
microbial population dynamics, endocrine disrupter
concentrations, and agronomic characteristics also were
determined.
The objectives of the bioaerosol and particulate matter
sampling plan developed by the USEPA were to
characterize the type and concentrations of select
biological agents and particulates at several exposure
points within 50 meters of the applied biosolids. The
analyses used included ones to detect and measure:
heterotrophic bacteria, fecal conforms, Escherichia coli,
Salmonella, Staphylococcus aureus, Enterococcus sp.,
Clostridium perfringens, total bacterial bioburden,
fungus, enteric virus, coliphage (MS2), and particulate
size fractions. The sampling process utilized both
mobile and stationary bioaerosol sampling units which
included SKC BioSamplers® (impingers) and Andersen 6
stage samplers (impactors).
The objectives of the volatile organic compounds (VOC),
volatile inorganic compounds (VIC), and odor monitoring
measurements were to determine the presence and
concentration of select compounds, both upwind and
downwind of the application area. A gas-
chromatography method was used to measure sulfur
and nitrogen compounds. A Fourier Transform Infrared
Spectroscopy (FTIR) unit was used to take real-time
measurements of VOCs in the field. Flux chambers
were used in the field to measure VOCs. Flux samples
were taken directly from the ground prior to application,
from the biosolids pile, and from the ground one and two
days after application. A portion of the flux samples
were analyzed by an odor panel; odor measurements
were also made in the field with the Nasal Ranger™
Olfactometer.
The objectives of the soil monitoring were to measure:
the amount and distribution of biosolids applied to the
field; the concentration of various microbial
contaminants over time; the concentration of endocrine
disruptive chemicals as a function of depth and time; the
microbial community as a function of depth and time;
and ecotoxicity before and after biosolids application.
Measurements were taken to detect the presence of
fecal conforms, some pathogenic bacteria, enteric
viruses, coliphage (MS2), and viable helminth ova.
This study required a considerable level of coordination
and communication among the research collaborators
because of the large study site. Quality
assurance/quality control (QA/QC) was complicated and
involved different agencies and offices. Data from this
project are a landmark for multi-media information
gathered from one site and may serve as a baseline for
future studies. A report on this study is in preparation.
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Pathogen Risk Assessment for Biosolids:
Recent Developments
Jeffrey A. Seller
Mr. Seller, with Seller Environmental, discussed a two-
phase WERF-funded project to develop a methodology
for assessing the risk of pathogen exposures from
biosolids. Microbiological contaminants of concern
include viruses, bacteria, protozoan parasites, and
helminths from a number of potential human exposure
pathways. The following exposure pathways were
investigated in the study: direct ingestion of biosolids-
amended soil, ingestion of groundwater containing
microbes leached through soil from land applied
biosolids; and exposure to wind transported microbes
from land applied biosolids. Potential important issues
in determining appropriate microbial risk assessment
(MRA) methods include both exposure-specific
parameters, such as magnitude and frequency of
exposure, and pathogen-specific factors, such as
infectious dose, disease, and infectivity. The study
results indicate that it is both feasible and reasonable to
apply a dynamic population-based MRA method to
estimate human health risk from pathogens in land
applied biosolids. The framework was completed in
2002 and published in a WERF report (2003) and in
Eisenberg et al., 2004. A demonstration of the
methodology has recently been completed.
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Sludge Fate and Transport
Analyzing Biosolids for Microorganisms to
Achieve Regulatory Compliance
Mark C. Meckes
Mr. Meckes, with USEPA's NRMRL, discussed an
evaluation of analytical methods for microbial monitoring
in biosolids materials. Current federal regulations
require monitoring for indicator microorganisms under
some conditions for Class B biosolids and under all
conditions for Class A biosolids. Standard protocols for
quantifying these organisms were specified in the
regulations; however, these protocols were not designed
for biosolids. Two alternatives for meeting Class A
requirements include monitoring for enteroviruses and
viable helminth ova. A guidance document, "Control of
Pathogens and Vector Attraction in Sewage Sludge"
(USEPA, 1992), includes a plaque assay for detection of
total culturable viruses and a protocol for enumeration of
viable helminth ova in biosolids.
Recently, methods used for analysis of fecal conforms
and Salmonella were reviewed and a standard protocol
was developed for biosolids applications. These
protocols were evaluated by testing various types of
biosolids at twelve laboratories throughout the U.S. Two
multiple fermentation tube methods were evaluated for
fecal conforms in biosolids, the lauryl tryptose broth
(LTB) - EC broth method and the A-1 method. A single
method for Salmonella was evaluated, the modified
semi-solid Rapaport-Vasiliadis procedure. Results
showed considerable variation between laboratories
depending upon the biosolids evaluated. The fecal
conforms and Salmonella methods have been included
as USEPA methods under 40 CFR 136. A similar study
evaluating methods for the detection and enumeration of
viruses has been initiated with the University of
Cincinnati.
Fate and Transport Models
Charles P. Gerba
Dr. Gerba, with the University of Arizona, discussed the
major factors to be considered in modeling fate and
transport of biosolids pathogens. The purpose of
developing these models is to provide a better
characterization of the exposure component of a risk
assessment. Some of the challenges in modeling
microbial transport are that: there are many different
species of microbes, some microbes may multiply in the
environment, and organisms are not evenly distributed in
the environment because they are particulate.
Furthermore, their survival and transport rates are
affected by weather and climate. Factors that need to be
included when modeling pathogen survival in soil or
water include temperature, soil moisture, and rate of
moisture loss. A major factor influencing virus survival in
the subsurface is temperature, which can be easily
measured and modeled. A more challenging factor is
that viral migration rates vary and are influenced by soil
type and saturation.
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Dermal Exposure
Non-invasive
Exposure
Karla D. Thrall
Assessment of Dermal
Dr. Thrall, with Pacific Northwest National Laboratory,
discussed the use of physiologically based
pharmacokinetic (PBPK) modeling to non-invasively
measure dermal adsorption. Volatile chemicals in
biosolids may be absorbed through the skin from the
soil. This compound can then pass into the bloodstream
and other tissues. The absorbed compound either
remains in the tissue or blood, or returns in the venous
blood and is exhaled. With each breath, some of the
compound is volatilized and exhaled, and by measuring
the exhaled air the amount of chemical absorbed can be
predicted. Breath analysis is conducted using a mass
spectrometer that takes real-time measurements. The
sample collection device is very simple, and has been
used on rats, mice, primates, and human volunteers.
Real-time breath analysis and PBPK modeling are
ideally suited to track the kinetics of dermal exposure.
The methodology is sensitive; therefore, human studies
can be conducted at low exposure concentrations.
Deployment of the technology with PBPK modeling
could improve industrial hygiene practices by enabling
onsite measurement of human exposure.
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Odors and Irritants
Odor, Irritation and Health Symptoms from
Biosolids
Pamela H. Dalton
Dr. Dalton, with the Monell Chemical Senses Center,
discussed airborne chemicals and odor and their effects
on humans. Volatile chemicals associated with
bioaerosols and particulates in biosolids may produce
ocular/airway irritation as well as emit objectionable
odors. These chemicals can therefore cause
annoyance, stress, and perception of health risks.
Irritation response ranges from mucosal burning to
upper respiratory irritation. However, the odor detection
threshold is at much lower concentration than the
irritation threshold.
Dynamic determinants affecting sensitivity to odor
include frequency, intensity, duration, and offensiveness.
Women in particular may become more sensitive with
intermittent, infrequent exposures. The way people are
exposed to odor affects the response to odors. Duration
of exposure can dramatically increase the sensory
impact and temporal factors play a huge role. One brief
exposure does not predict the results from longer
exposure.
An important unresolved issue is whether odors
associated with land application of biosolids elicit health
symptoms through direct action on target organs or from
annoyance. Key data gaps in evaluating the effects of
biosolids odors include: documenting actual exposure
and effects in communities, identifying key odors and
irritants in biosolids, and evaluating the response
variation due to temporal factors, individual sensitivity,
and attitudes and expectations.
Odor Measurements and Impacts from an
Experimental Biosolids Land Application
Site
Robert H. Forbes, Jr.
Mr. Forbes, with CH2M Hill, discussed a study involving
onsite and laboratory analysis of odor samples taken at
a North Carolina biosolids land application site before,
during, and after application. A certified offsite panel
was used for odor analysis of three flux-chamber
samples taken on the day before (-1), the day of (0), and
the day after (1) land application. Hand-held Nasal
Ranger™ olfactometers were used for field assessment
of odors. Chemical sensory tubes were used for field
measurements of ammonia and a Jerome gold-film
analyzer was used for field measurements of hydrogen
sulfide. The offsite panel and Nasal Ranger™ test
results indicated odor increased on day 0 and 1 when
compared to day -1. Odors were not detected more
than 200 feet from the application site. Odors began
subsiding on day 2, and were not detected by day 4.
Ammonia and hydrogen sulfide disperse rapidly in air
and were detected only directly above the applied
biosolids immediately after application. Most lingering
odors appear to be due to organic sulfur compounds
such as methyl mercaptan, dimethyl sulfide, and
dimethyl disulfide, or nitrogen-based compounds such
as trimethyl amine, indole, and skatole. Odors can be
reactivated by changes in temperature or rain events.
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Particulates
Airborne Particulates:
Measurement Issues
Patricia D. Millner
Technologies and
Dr. Millner, with USDA, discussed airborne participates
and exposure assessment issues. Airborne particles of
concern are those that are breathable and could cause
adverse health effects. Whether health effects occur
after exposure to particulate matter is dependent on
several factors, including: particle size, exposure
intensity and duration, the chemical/biological nature of
the particles, the length of time that a particle remains in
the air, and the presence of pre-existing conditions (e.g.,
asthma). A number of different air samplers are
available such as impingers, cyclones, particle counters,
impactors, filters, and dustfall deposit gauges. Each
sampler samples at a different rate, ranging from 1.2
L/min to 400 L/min, and has different sample volumes.
Several factors need to be considered when sampling
land applied biosolids for aerosols. The application site
needs to be sampled before biosolids application with
mock conditions and during the application. An upwind
reference site also needs to be sampled. Biosolids are
applied by a mobile source which typically applies the
material in a directional manner; therefore, sampling
location and mobility are critical factors in determining
exposure. In addition, meteorological data such as wind
speed and direction, the analytical method, background
levels of particulates, and the effects of sample
collection conditions upon the analyte (desiccation or
shearing forces) need to be considered in the analytical
and sampling plans.
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Pathogens and Endotoxins
Biomarkers of Viral Exposure
G. Shay Fout
Dr. Fout, with NERL, discussed a USEPA Office of
Research and Development (ORD) study entitled
"Salivary Antibody Responses as an Indicator of
Waterborne Infections: Pilot Community Study Before
and After Installation of UV Treatment." The study is
novel both because of its design and because the use of
new approaches to determine pathogen exposure.
Although this study is aimed at detecting exposure to
pathogens in water, it could serve as a model for future
studies aimed at determining the health risks associated
with the application of biosolids.
This intervention study has been designed to correlate
pathogen occurrence in water with exposure and health
effects. Specifically, individuals will be surveyed before
and after a new drinking water treatment plant with
ultraviolet disinfection goes online. Volunteer families
will provide health data by completing questionnaires
and by providing monthly saliva samples. These
samples will be tested for antibodies to Cryptosporidium,
norovirus, and rotavirus. In addition, water samples will
be taken to determine the occurrence of these
waterborne pathogens.
In addition to the unique overall design, this study takes
advantage of a new approach to detect exposure by
testing for the presence of specific biomarkers
(antibodies) found in saliva samples. Traditional indices
for estimating pathogen exposure in a community
include: individual symptom surveys, school illness
records, and pharmaceutical sales. Unfortunately, these
indices are not effective for estimating the risk from
biosolids exposure because of the lack of a proper
control population. In addition, these indices are
generally not pathogen specific. In contrast, biomarkers
for measuring exposure, such as direct pathogen assays
and antibody responses in serum or oral fluids, can
more directly target individuals that are likely to be
exposed as well as control individuals who are not
affected. In addition, antibody assays are pathogen
specific and can be used to approximate the time of
exposure.
The specific saliva-based assay used in this study,
which takes advantage of a novel fluorescent bead array
LiquiChip™ technology to determine antibody levels,
has several advantages. Unlike a serum-based assay
for biomarkers, a saliva-based antibody assay is not
invasive. This feature allows individuals at a range of
ages to participate, enhances participation of the entire
community, and provides significantly reduced specimen
collection costs. In addition, the LiquiChip™ assay is
more sensitive and reproducible than the standard
ELISA with lower costs and analysis time.
Community and Occupational Risk from
Bioaerosols during Land Application of
Biosolids
Ian L. Pepper
Dr. Pepper, with the University of Arizona, discussed two
studies evaluating occupational and community risk from
bioaerosols during land applications of biosolids.
Bioaerosol samples were collected with SKC
BioSampler® impingers from land application sites
located across the U.S., using different application
practices, such as liquid spray and "cake" application.
Samples were collected from downwind and background
sites. The concentrations of several microbes were
measured, including: heterotrophic plate count bacteria
(HPC), total conforms, coliphage, Clostridium
perfringens, Escherichia coli, endotoxin
(lipopolysaccharide), enterovirus, norovirus, and
hepatitis A virus (HAV). Overall, in 500 samples
analyzed, the levels of bacteria and phage were at or
below detection limits by culture methods, and only three
samples were positive for norovirus by reverse
transcription PCR. Calculated risk of infection in the
community was determined to be at or below a 1:10,000
risk of annual infection. Endotoxin concentrations
observed during land application were similar to those
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observed from tractor operations without biosolids,
implying that the endotoxins are from the soil.
Occupational risk studies included three experiments to
characterize the concentration of aerosolized
microorganisms from biosolid applications, the plume
created during land application, and the occupational
risk of infection from land application of biosolids. More
than 300 air samples were collected downwind of
biosolids application sites using liquid impingers, and
over 100 samples were collected downwind of
microbially seeded, land applied water samples. The
seeded water served as a model system for tracking the
plume. The aerosolization rates from land application of
biosolids were calculated to be less than 33 plaque
forming units (PFU) of coliphage and 10 colony forming
units (CPU) of conforms per meter traveled, while the
water aerosolization rates were much higher. Exposure
duration was brief and limited to the time when the
biosolids were in the air. Samples also were taken from
air and biosolids at 10 land application sites from across
the U.S. and analyzed for conforms, coliphages, and
HPC. The application method strongly influenced
aerosolization rates, while relative humidity, temperature
and wind speed showed limited effects. Occupational
risks of infection from land application are greatest
during the loading of biosolids. Both studies indicate
that occupational or community exposure to viruses and
bacterial indicators is low during and after land
application of biosolids, at least for the meteorological
conditions evaluated.
Improving the Efficiency of an Impinger for
Collecting Bacteria during a Biosolids
Application Field Study
Edwin F. Barth
Dr. Barth, with USEPA's NRMRL, discussed the use of
impingers for bioaerosol sample collection. Measuring
individual airborne exposure accurately is challenging
because of the difficulty of matching air sampling
devices to different respiratory mechanisms, deposition
sizes, and personal breathing heights. In addition, the
survival of microorganisms is dependent upon their size,
the relative humidity, time, temperature, and UV and
ozone exposure. Traditional bioaerosol collection
methods include filtration, impaction, and impingement.
Advantages of impingement include: longer sampling
times (up to 8 hours), the ability to split aliquots for
multiple analyses, suitability for molecular methods, and
sample direction flexibility. Disadvantages of
impingement include the delicate, relatively expensive
equipment, and the stress-induced effects on the
microorganisms during collection. Research conducted
in the field and at the NRMRL Bioaerosol Wind Tunnel
evaluated the performance of SKC BioSampler®
impingers. The results suggest that modifications to the
standard practices involving impinger use will improve
recoveries. These modifications include covering of the
impinger apparatus to block UV radiation, washing of the
inlet neck to prevent drying of the accrued material
during sampling, and rinsing the inlet neck and jets after
collection to liberate organisms captured in the neck.
Endotoxins
Nancy C. Burton
Ms. Burton, with the Center for Disease Control and
Prevention's National Institute for Occupational Safety
and Health (CDC-NIOSH), discussed endotoxin
sampling techniques and analytical methods.
Endotoxins are a lipopolysaccharide complex formed in
gram negative bacteria that are chemically and thermally
stable. Endotoxins can cause powerful inflammatory
reactions in humans with symptoms including fever, flu-
like symptoms, cough, headache, asthma, and/or
respiratory distress. Other associated health effects
include organic dust syndrome and respiratory disease
such as asthma. Occupational groups with highly
documented exposures include farmers, cotton workers,
wastewater treatment workers, trash haulers, and
poultry and swine handlers. One method for sampling
endotoxins uses 0.4 urn pore size endotoxin-free
polycarbonate filters in cassettes, and filter/cassette
vacuum collectors. The analytical methods used include
the Limulus amebocyte kinetic assay, the kinetic
chromogenic method, and the gas chromatography-
mass spectrometry method.
Occupational Exposure Assessments at
WWTPs
Nancy C. Burton
Ms. Burton discussed exposure routes, contaminants,
and sampling techniques used for occupational
exposure assessments of workers at WWTPs. These
assessments are a conservative estimate of community
exposure to biosolids since the contaminant loads are
thought to be the highest at the WWTP. In addition,
these assessments are site specific because the
exposure risks are dependent upon the incoming
wastes, treatment process, and job tasks. When
identifying potential hazards, it is necessary to relate the
environmental evaluation to any reported health
symptoms. Assessments at WWTPs should include a
consideration of chemical, biological, and onsite physical
hazards. The chemical and biological contaminants are
primarily concentrated in the sludge.
Exposure routes for chemical and biological
contaminants are inhalation, ingestion, and dermal
adsorption. Chemicals in the waste stream include
11
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gaseous by-products (carbon monoxide, methane, of approaches, including cultural techniques,
ammonia, and hydrogen sulfide), dewatering agents, microscopic analysis (spore traps and surface), and
and trace metals. Human pathogens that may be found polymerase chain reaction (PCR) techniques. Some
in sludge include bacteria, viruses, protozoa, and considerations for field monitoring of biological agents
helminths. There are no specific occupational exposure include sample storage, transport, aerosol range, and
criteria to infectious agents in wastewater or sewage. sampling and analytical methods.
Biological contaminants are identified through a variety
12
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Panel Discussion Session
Bruce Mintz charged the workshop participants to
recommend an exposure measurement protocol, and to
identify research needs for measuring exposure. In
addition, several other topics related to incident
response and biosolids practices were discussed.
Because of the complexity of biosolids and the multiple
exposure pathways, an exposure measurement protocol
framework could not be recommended at the present
time. However, it was agreed that the protocol should
include multiple exposure routes and contaminants,
much like the approach used in the North Carolina field
study. The following is a summary of the panel
discussion.
The development of an exposure measurement
framework is hindered by a lack of knowledge about the
nature of complaints and health effects associated with
biosolids land application. The lack of an incident
response protocol prevents health complaints
associated with land applications from being
systematically recorded by local and state authorities. It
also prevents the classification of complaints by
symptom (such as respiratory effects, gastroenteritis,
skin irritation, odor/nuisance, and headaches) or by
exposure pathway (air, soil, or water). Epidemiological
studies of the effects of biosolids land application are
needed, with better analyses of baseline and post-
application exposure and health information. In most
situations there are only a few complaints; how well this
correlates with the total number of people who may be
affected is unknown. It is also unclear if there is a
relationship between complaints and such factors as
educational level or health insurance coverage. To
better evaluate community exposure, complaints and
health effects should be mapped around the application
site with the prevailing weather conditions indicated.
Real time measurements are needed. This information
would make it possible to define the relationship
between the number and severity of complaints and the
distance from application site.
The next theme discussed was biosolids treatment
practices. The panel felt many complaints are likely due
to the odor of the applied biosolids. The 503 regulations
were designed to reduce pathogens and vector
attraction but not control odor. The relationship between
vector control, odor generation, treatment practices, and
digestion level needs refinement. In addition, the effects
of various storage and curing practices need to be
evaluated when sludges are composted. Many biosolids
products do not generate complaints but some products
and operations are problematic. As such, treatment
practices should be optimized when necessary. Some
alternatives to improving treatment would include
applying biosolids in remote areas or injecting them into
the soil. The panel felt that exposure and complaints
could be greatly reduced by changing the recommended
best practices for sludge treatment and biosolids
application processes so that odors were reduced.
The third theme discussed was the use of biosolids
indicators. A biosolids indicator could be used to trace
movement of contaminants after application, to study
decay rates, and to plot source curves. Caffeine, fibers,
steroidal aerosols, specific microbes, fugitive dust or
other substances that occur in biosolids are possible
targets. A true indicator would need to distinguish
biosolids from manure or septage. Since indicators do
not provide specific information about the cause of a
complaint and do not necessarily correlate with the
transport properties of a specific contaminant, they may
be only useful as a screening or research tool.
The final themes discussed were exposure
measurement, analytical methods, and research
priorities. To answer basic exposure questions, the
broad and indicator-based exposure measurement
approach taken in the North Carolina field study is
appropriate. Indicators would not be appropriate for
incident response because the sampling and analytic
approach needs to be specific to the complaint and site.
This means that the compounds or organisms
associated with complaints need to be identified. In
general, analytical methods may need to be developed,
and more real-time monitoring is needed before, during,
and after the application of biosolids both onsite and in
the surrounding community.
During the panel discussion, several research needs
became apparent, especially in the area of pathogen
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and odor exposure. The evaluation of exposure to
microorganisms associated with biosolids application,
particularly aerosolized pathogens, needs further
research. The health effects of fungi may need to be
evaluated because soil has a higher fungal burden after
biosolids application. Adding to the complexity of
monitoring is the interpretation of results due to the fact
that microorganisms are present without biosolids
application; therefore, ambient background levels need
to be determined. The sample planning process should
carefully consider the number of samples needed so that
the amount of exposure can be accurately estimated.
Sampling methods, such as impactors and impingers,
should be evaluated to define both their recovery rate
and effects upon the stress-sensitive microorganisms
that are trapped.
Measurement of exposure to odors also has many
research gaps, in part because irritation and health
effects from chemical aerosols are dependent upon
dose, duration of exposure, and concentration. Other
undefined volatile chemicals, not just hydrogen sulfide
and ammonia, cause odor in biosolids. These
compounds are likely to be found at extremely low
concentrations, vary among sites, and have different
migration rates and detection thresholds than hydrogen
sulfide or ammonia. The time of day also affects odor
sample results with the odors being strongest overnight.
In addition, the health effects caused by tasteless,
odorless materials found in biosolids (PM2.5 or
chemicals) need to be determined.
Priority Research Needs
1. Characterize the sites, biosolid products, and
biosolids application processes that generate
complaints, and change either the sludge
treatment or biosolids land application
processes.
2. Identify the source of complaints and health
effects; specifically, the microorganisms or
chemicals that cause complaints. If possible
correlate field measurements to health effects.
3. Improve data collection and analysis of
complaint incidents.
4. Measure microbial exposure levels before and
after land application in controlled long-term
research projects.
5. Characterize VOC and odor emissions from land
application sites, and other agricultural sites.
6. Evaluate and improve bioaerosols exposure
methods, including the direct comparison of
microbial sample collection systems.
7. Measure real-time endotoxin concentrations at
application sites and other agricultural sites.
8. Measure odor at land application sites before,
during, and after application. Compare the odor
levels to upwind and downwind sites.
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Bibliography
Eisenberg, J., Seller, J., Scott, J., Eisenberg, D., and
Colford, J. (2003). A dynamic model to assess microbial
health risks associated with the beneficial uses of
biosolids. WERF: Alexandria, VA.
Eisenberg, J., Seller, J., Scott, J., Eisenberg, D., and
Colford, J. (2004). A dynamic model to assess microbial
health risks associated with the beneficial uses of
biosolids. Risk Analysis 24: 221-236.
NRC. (2002). Biosolids applied to land: advancing
standards and practices. National Academy Press:
Washington DC.
USEPA. (1989). National primary drinking water
regulations; filtration and disinfection; turbidity; Giardia
lamblia; and heterotrophic bacteria. Federal Register.
54: 27486-27541.
USEPA (1992) Control of pathogens and
attraction in sewage sludge. EPA/625/R-92/013.
vector
USEPA. (1993). Standards for the use or disposal of
sewage sludge. 40 Code of Federal Regulations Part
503 (40CFR503).
USEPA. (2003). Final Agency response to the National
Research Council Report on biosolids applied to land
and the results of EPA's review of existing sewage
sludge regulations. Federal Register. 68: 75531-75552.
WERF. (2004). Biosolids Research Summit Report.
WERF: Alexandria, VA.
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Appendix A
Biosolids Exposure Measurement Workshop Agenda
Andrew W. Breidenbach Environmental Research Center
Cincinnati, OH
Thursday, March 16, 2006
Introduction Session
8:30-9:45 Workshop Background and Objectives
Bruce Mintz, USEPA
Land Application and Sludge Treatment
James E. Smith, USEPA
Protocols for the Timely Investigation of Potential Health Incidents Associated with Biosolids Land
Application
Alfred P. Dufour, USEPA
Community Perspective of Land Application
Maureen Reilly, Sludgewatch
9:45-10:00 Break
Current Exposure Measurement Methods and Risk Assessment
10:00-11:00 Multi-Media Sampling at a Biosolids Land Application Test Site
Eric A. Foote, Battelle
11:00-11:30 Pathogen Risk Assessment for Biosolids: Recent Developments
Jeffrey A. Seller, Seller Environmental
11:30-12:45 Lunch
Sludge and Fate and Transport
12:45-1:15 Analyzing Biosolids for Fecal Conforms and Salmonellae
Mark C. Meckes, USEPA
1:15-1:45 Fate and Transport Models
Charles P. Gerba, University of Arizona
Dermal Exposure
1:45-2:15 Non-invasive Assessment of Dermal Exposure
Karla D. Thrall, Pacific Northwest National Laboratory
Odors and Irritants
2:15-2:45 Odor, Irritation and Health Symptoms from Biosolids
Pamela H. Dalton, Monell Chemical Senses Center
2:45-3:00 Break
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3:00-3:30 Odor Measurements and Impacts from an Experimental Biosolids Land Application Site
Robert H. Forbes, Jr., CH2M Hill
Particulates
3:30-4:00 Airborne Particulates: Technologies and Measurement Issues
Patricia D. Millner, USDA
Pathogens and Endotoxins
4:00-4:30 Biomarkers of Viral Exposure
G. Shay Fout, USEPA
Friday, March 17,2006
8:40-9:10 Community and Occupational Risk from Bioaerosols during Land Application of Biosolids
Ian L. Pepper, University of Arizona
9:10-9:40 Improving the Efficiency of an Impinger for Collecting Bacteria during a Biosolids Application Field
Study
Edwin F. Barth, USEPA
9:40-10:10 Endotoxins
Nancy C. Burton, CDC-NIOSH
10:10-10:30 Break
10:30-11:00 Occupational Exposure Assessments at WWTPs
Nancy C. Burton, CDC-NIOSH
11:00-2:00 Panel Discussion Session
(Lunch during session)
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Appendix B
Participant List
Carolyn Acheson
Chemical Engineer
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7190
Email: acheson.carolyn@epa.gov
Bethany Acquisto
Environmental Engineer
USEPA-NRMRL
26 West Martin Luther King Drive, MS-G75
Cincinnati, OH 45268
Phone:513-569-7690
Email: acquisto.bethany@epa.gov
Adam Balz
Chemist
Pegasus Technical Services, Inc.
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7107
Email: balz.adam@epa.gov
Ed Earth
Environmental Engineer
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7669
Email: barth.ed@epa.gov
Robert Bastian
Senior Environmental Scientist
USEPA-OW-OWM
1200 Pennsylvania Avenue, NW, 4204M
Washington, DC 20460
Phone: 202-564-0653
Email: bastian.robert@epa.gov
Benjamin Blaney
Assistant Laboratory Director
USEPA-NRMRL
26 West Martin Luther King Drive MS-235
Cincinnati, OH 45268
Phone:513-569-7852
Email: blaney.ben@epa.gov
Bryan Boulanger
Environmental Engineer
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7018
Email: boulanger.bryan@epa.gov
Richard Brenner
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7657
Email: brenner.richard@epa.gov
Nichole Brinkman
Microbiolgist
USEPA-NERL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7315
Email: brinkman.nichole@epa.gov
Nancy Burton
Industrial Hygienist
CDC/NIOSH
4676 Columbia Parkway, MS R-11
Cincinnati, OH 45226
Phone:513-841-4323
Email: nburton@cdc.gov
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Mark Chappell
ORISE Postdoctoral Fellow
USEPA
809 Heavenly Lane
Cincinnati, OH 45238
Phone:513-922-2442
Email: chappell.mark@epa.gov
Patrick Clark
Physical Scientist
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7561
Email: clark.patrick@epa.gov
Kawana Cohen
Biosolids Permitting Coordinator
USEPA-OW-OWM
1200 Pennsylvania Avenue, 4203M
Washington, DC 20460
Phone: 202-564-2435
Email: cohen.kawana@epa.gov
Tracy Dahling
Physical Science Technician
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7429
Email: dahling.tracy@epa.gov
Pamela Dalton
Member
Monell Chemical Senses Center
3500 Market Street
Philadelphia, PA 19104
Phone:215-898-5595
Email: pdalton@pobox.upenn.edu
Armah de la Cruz
Scientist
USEPA-NERL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7224
Email: delacruz.armah@epa.gov
Maura Donohue
Research Chemist
USEPA-NERL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7634
Email: donohue.maura@epa.gov
Alfred Dufour
USEPA-NERL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7330
Email: dufour.alfred@epa.gov
Eric Foote
Principal Research Scientist
Battelle
505 King Avenue
Columbus, OH 43201
Phone:614-424-7939
Email: foote@battelle.org
Robert Forbes
Senior Technologist
CH2M HILL, Inc.
4824 Parkway Plaza Boulevard, Suite 200
Charlotte, NC 28217
Phone: 704-329-0073 ext. 213
Email: bob.forbes@ch2m.com
Shay Fout
Microbiologist
USEPA-NERL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7387
Email: fout.shay@epa.gov
Charles Gerba
The University of Arizona
2601 East Airport Drive
Tucson, AZ 85706
Phone:520-621-6906
Email: gerba@ag.arizona.edu
Ann Grimm
Branch Chief
USEPA-NERL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7397
Email: grimm.ann@epa.gov
Alan Hais
Senior Program Director
WERF
635 Slaters Lane
Alexandria, VA 22314
Phone: 703-684-2470 x7146
Email: ahais@werf.org
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Margaret Hardebeck
Research Associate, M.L.T.
Pegasus Technical Services, Inc.
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
Phone:513-569-7611
Email: hardebeck.margaret@epa.gov
Evelyn Hartzell
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7728
Email: hartzell.evelyn@epa.gov
Fred Hauchman
Division Director
USEPA-NERL
26 West Martin Luther King Drive
MD-593
Cincinnati, OH 45268
Phone:513-569-7007
Email: hauchman.fred@epa.gov
Richard Haugland
Microbiologist
USEPA-NERL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Email: haugland.richard@epa.gov
Gina Hayes
Contractor
USEPA
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7953
Email: hayes.gina@epa.gov
Christopher Heaney
Doctoral Student
Department of Epidemology CB# 7435
School of Public Health
University of North Carolina at Chapel Hill
Chapel Hill, NC
Phone:919-423-6441
Email: cheaney@email.unc.edu
Michelle Henderson
QA Manager
Shaw Environmental, Inc.
5050 Section Avenue
Cincinnati, Ohio 45212
Phone:513-782-4763
Email: michelle.henderson@shawgrp.com
Gerard Henderson
EHS Monitor
Pegasus Technical Services, Inc.
Center Hill Facility
5995 Center Hill Avenue
Cincinnati, OH 45224
Phone:513-569-7868
Email: henderson.gerard@epa.gov
Ronald Herrmann
Microbiologist
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45468
Phone:513-569-7741
Email: herrmann.ronald@epa.gov
Edith Holder
Research Associate
Pegasus Technical Services, Inc.
46 East Hollister Street
Cincinnati, OH 45219
Phone:513-569-7178
Email: holder.edith@epa.gov
Pyoungchung Kim
Doctoral Student
University of Tennessee
1611 Laurel Avenue, #1115
Knoxville, TN 37916
Phone: 865-924-5892
Email: pkim1@utk.edu
Karen Koran
Onsite Manager
Pegasus Technical Services, Inc.
26 West Martin Luther King Drive
ML 421
Cincinnati, OH 45268
Phone:513-569-7304
Email: koran.karen@epa.gov
Drew Luellen
Research Scientist
Virginia Institute of Marine Science
1208 Create Road, Box 1346
Gloucester Point, VA 23062
Phone: 804-684-7749
Email: luellen@vims.edu
Ruth Marfil-Vega
Research Associate
UC/Pegasus Technical Services, Inc
26 West Martin Luther King Drive
Cincinnati, Ohio 45220
Phone:513-807-5332
Email: marfil-vega.ruth@epa.gov
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Jonathan May
Graduate Student
Medical University of Ohio/NOCPH
Phone: 785-545-5821
Email: jmay@medohio.edu
Paul McCauley
Chemist
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45468
Phone:513-861-3348
Email: Paul82346@yahoo.com
Deborah McKean
Toxicologist
USEPA-NDT
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-487-2435
Email: mckean.deborah@epa.gov
Mark Meckes
Microbiologist
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, Ohio 45268
Phone:513-569-7348
Email: meckes.mark@epa.gov
Patricia Millner
Research Microbiologist
USDA-ARS-BARC
10300 Baltimore Avenue, Building 001, Room 140
Beltsville, MD 20705-2350
Phone:301-504-7199
Email: millnerp@ba.ars.usda.gov
Bruce Mintz
Assistant Lab Director
USEPA-NERL
109 TW Alexander Drive
RTP, NC 27709
Phone:919-541-0272
Email: mintz.bruce@epa.gov
Felipe Alatriste Mondragon
Environmental Engineering and Natural
Resource Management
Camino a la Presa San Jose
2055 Lomas 4a
Seccion, C.P. 78216
San Luis Potosi, S.L.P., Mexico
Phone: +52 444-834-20-00
Email: falatriste@ipicyt.edu.mx
Michael Moore
Manager
Orange County Sanitation District
10844 Ellis Avenue
Fountain Valley, CA 92708
Phone:714-962-2411
Email: mmoore@ocsd.com
Regan Murray
USEPA-NHSRC
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7031
Email: murray.regan@epa.gov
Tonya Nichols
USEPA-NHSRC
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7805
Email: nichols.tonya@epa.gov
Xuejun Pan
Research Associate
University of Cincinnati
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7354
Email: pan.xuejun@epa.gov
Sandhya Parshionikar
Microbiologist
USEPA-OW
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7123
Email: parshionikar.sandhya@epa.gov
Bruce Peirano
Toxicologist
USEPA-NRMRL
26 West Martin Luther King Drive
MD690
Cincinnati, Ohio 45268
Phone:513-569-7540
Email: peirano.bruce@epa.gov
Ian Pepper
Director
The University of Arizona
2601 East Airport Drive
Tucson, AZ 85706
Phone: 520-626-3328
Email: ipepper@ag.arizona.edu
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Amit Pramanik
WERF
635 Slaters Lane, Suite 300
Alexandria, VA 22314-1177
Phone: 703-684-2470
Email: apramanik@werf.org
Shuang Qi
Senior Environmental Engineer
Pegasus Technical Services Inc.
26 West Martin Luther King Drive
ML 421
Cincinnati, OH 45268
Phone:513-5697819
Email: qi.shuang@epa.gov
Maureen Reilly (presentation via phone)
Executive Director
Sludgewatch
103 Avenue Road, #601
Toronto, Ontario, Canada
Phone:416-801-4099
Email: maureen.reilly@sympatico.ca
Mark Rodgers
Microbiologist
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7225
Email: rodgers.mark@epa.gov
Alan Rubin
Principal
Envirostrategies, LLC.
3304 Mill Cross Court
Oakton, VA
Phone: 703-385-8203
Email: rubinhial@cox.net
James Ryan
Soil Scientist
USEPA-NRMRL
5995 Center Hill Avenue
Cincinnati, OH 45268
Phone:513-569-7653
Email: ryan.jim@epa.gov
Yonggui Shan
Senior Research Associate
University of Cincinnati
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7606
Email: shan.yonggui@epa.gov
Marietta Sharp
Environmental Scientist
Washington Department of Ecology
3190 160th Avenue, S.E.
Bellevue, WA 98008
Phone: 425-649-7258
Email: mars461@ecy.wa.gov
Mano Sivaganesan
Statistician
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7118
Email: sivaganesan.mano@epa.gov
James Smith
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7355
Email: smith.james@epa.gov
Curtis Snook
Medical Officer
USEPA, NOT
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-487-2434
Email: snook.curtis@epa.gov
Jeff Seller
Principal Scientist
Seller Environmental
3022 King Street
Berkeley, CA 94703
Phone:510-847-0474
Email: jsoller@sollerenvironmental.com
Laurel Staley
Branch Chief
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7863
Email: staley.laurel@epa.gov
Gerard Stelma
Senior Science Advisor
USEPA-NERL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7384
Email: stelma.gerard@epa.gov
22
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Rick Stevens
Biologist
USEPA-OW-OST
1200 Pennsylvania Avenue, 4304T
Washington, DC 20460
Phone:202-566-1135
Email: stevens.rick@epa.gov
Karla Thrall
Staff Scientist
Pacific Northwest National Laboratory
902 Battelle Boulevard, Mail Stop P7-59
Richland, WA 99352
Phone:509-376-6115
Email: karla.thrall@pnl.gov
Eunice Varughese
Microbiologist
USEPA-NERL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7628
Email: varughese.eunice@epa.gov
Michael Ware
Microbiologist
USEPA-NERL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7731
Email: ware.michael@epa.gov
Alan Weinrich
USEPA-NHSRC
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7860
Email: weinrich.alan@epa.gov
Karen White
Bio Science Technician
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7248
Email: white.karenm@epa.gov
Steve Wing
Associate Professor
UNC Department of Epidemiology
CB# 7435, School of Public Health
Chapel Hill, NC
Phone:919-966-7416
Email: steve_wing@unc.edu
Stephen Wright
Environmental Scientist
USEPA-NRMRL
26 West Martin Luther King Drive
Cincinnati, OH 45268
Phone:513-569-7610
Email: wright.stephen@epa.gov
Eric (Xueqing) Zhu
Senior Environmental Engineer
Pegasus Technical Services, Inc.
26 West Martin Luther King Drive
ML 421
Cincinnati, OH 45268
Phone:513-569-7571
Email: zhu.xueqing@epa.gov
23
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Appendix C
Update on Incident Response Project
Project Signed, Work Begun on Timely Incident
Response
A new WERF research effort, Methodology for
Implementing a Timely Incident Response Mechanism
(03-HHE-5PP), was started under the lead of Principal
Investigator Steve Wing with the University of North
Carolina. The first phase of the project will develop a
protocol to be used in conjunction with established
public health investigation procedures and
implemented through the existing network of public
health organizations. The protocol will be designed to
help determine if, among all potential causes, reports
of illness in a community could be associated with
biosolids land application or possibly other soil
amendment practices.
Proper implementation of the protocol by local, state,
and federal agencies could provide information about
the occurrence of reported symptoms in proximity to
biosolids land applications sites and the times and
places where reports are more common.
Implementation of the protocol could also help provide
the basis for conducting more definitive studies of
causal links between human exposures from all
potential sources and health effects. The current
project does not include implementation.
This project was the highest ranked priority at the
2003 Biosolids Research Summit, during which a
group of nearly 75 individuals representing agencies,
conservation groups, wastewater facilities, academia,
and citizens identified their most pressing research
needs regarding land application of biosolids. This
research responds to a July 2002 report from the
National Research Council (NRC) of the National
Academy of Sciences regarding potential health risks
related biosolids.
Oct. 5, 2006
http://www.werf.org/press/News Events.cfm
24
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Appendix D
Technical Reports
Appendix D contains five technical reports that expand
upon the information presented at the workshop. The
titles and authors of the technical papers are:
• Non-Invasive Assessment of Dermal
Exposure by Karla Thrall
• Odor, Irritation, and Health Symptoms from
Biosolids Land Applications by Pamela Dalton
• Detection and Measurement of Odor,
Ammonia, and Hydrogen Sulfide Emissions as
Part of USEPA Biosolids Land Application
Research Project by Robert Forbes
• Community and Occupational Risk from
Bioaerosols during Land Application of
Biosolids by Ian Pepper
• Lessons Learned Regarding the Use of an
Impinger for Collecting Airborne Bacteria
during a Biosolids Application Field Study by
Edwin Barth
The first four papers were submitted by scientists not
employed by the USEPA. As such, these papers were
not reviewed by the Agency prior to inclusion in these
proceedings. The last paper by Edwin Barth, an
Agency scientist, was reviewed before publication in
accordance with USEPA policy.
25
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Appendix D-1
Non-Invasive Assessment of Dermal Exposure
Karla D. Thrall
Pacific Northwest National Laboratory
Abstract
Realistic estimates of dermal bioavailability following
exposures to volatile solvents in the workplace, or
through contaminated soil and water, are critical to
understanding human health risk. Compared to
dermal exposures with neat or aqueous compound,
little is understood about the dermal bioavailability of
solvents in soil, dust, sludge, or sediment matrices. A
method has been developed to determine dermal
uptake of solvents under non-steady state conditions
using real-time breath analysis. The exhaled breath
data is subsequently analyzed using physiologically
based pharmacokinetic (PBPK) models to estimate the
dermal permeability coefficient (Kp). This approach
has been utilized in both experimental animal and
controlled human exposures, with studies conducted
to compare the impact of exposure matrix, occlusion
versus non-occlusion exposure techniques, and
species-differences. To date, studies have clearly
illustrated that the methodology is sufficiently sensitive
to enable the conduct of animal and human dermal
studies at low exposure concentrations over small
body surface areas, for short periods of time. Further,
the portability of the system allows the methodology to
be used to conduct occupational and environmental
exposure assessments to volatile compounds.
Introduction
Traditional exhaled breath analysis techniques have
involved collection of breath samples in Tedlar bags or
stainless steel canisters, followed by laboratory
analysis - generally by gas chromatography.
Disadvantages of these techniques include the
possibility that the collection device may alter the
integrity of the sample, the time-consuming and costly
analysis of the sample, and the delay between sample
collection and analysis. To overcome these
disadvantages, a breath-inlet device for a mass
spectrometer was developed to allow for the
continuous real-time analysis of undiluted exhaled air
from experimental animals and humans (Thrall and
Kenny, 1996; Thrall et al. 2001). The applications of
this system in studies ranging from occupational
exposure assessment to applied research are
described here.
Exhaled Breath Analysis System
The breath monitoring system utilized in all the
described studies consisted of an inlet device
connecting a human volunteer directly with a mass
spectrometer. The subjects' exhaled breath is passed
through a heated large-diameter transfer line into a
heated glass-mixing chamber (1.3-L volume). A
breath sample enters the mixing chamber via a tube
that bends off to one side, and exits the chamber via a
tube bending in the opposite direction, thus
maximizing turbulence and mixing. A mass
spectrometer continually withdraws air samples from
the center of the mixing chamber at a calibrated rate.
Excess exhaled air is vented from the mixing chamber
via a large diameter bore-hole exit tube with negligible
flow restriction.
For rodent studies, animals are individually placed in
small off-gassing chambers. The animals are awake
and unrestrained while in the chamber. Hospital grade
(grade D) breathing air is supplied to the animal
through the lid of the chamber at a calibrated rate of
approximately 200 ml/min. The mass spectrometer
continually withdraws air samples from the mixing
chamber through a port in the chamber lid at the same
rate of approximately 200 ml/min. The concentration
of compound in the chamber is used to represent
exhalation from the animal.
26
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Inhalation
Exposure
Intravenous-
Infusion
, /
/}
Alveolar Air
Lung Blood
Richly Perfused
Tissue
Slowly Perfused
Tissue
Skin *
Fat
Kidney
Liver
t
Gl Tract
— i" Exhaled Air
Dermal
Exposure
Exposure
Figure 1: General structure of a PBPK model used to describe pharmacokinetics, tracking uptake from an oral, intravenous
injection, inhalation, or dermal exposure, distribution into tissues of concern, metabolism, and elimination of the parent compound
and/or metabolites in exhaled breath, blood, urine, and feces
Exhaled breath data can be related to total exposure
and internal target tissue dose through the use of
physiologically based pharmacokinetic (PBPK)
modeling. These physiologically relevant models are
powerful tools that can be used to simulate a chemical
exposure, regardless of route, and estimate the
amount of the compound or its metabolite at a
particular internal target. A PBPK model is based on
physiology (tissue or organ volumes, blood flow rates,
breathing rates, gender-specific physiology, etc.),
chemical characteristics (partition coefficients, density,
binding characteristics, etc.), and biochemical factors
(enzyme-specific metabolic rates, etc.). These factors
are either available in the literature, or can be
determined in focused in vitro or in vivo studies.
A PBPK model, such as illustrated in Figure 1,
describes the body as a series of tissue compartments
representing the probable route(s) of exposure, the
metabolically active tissues, target organs, and
excretion pathways. These models are typically
developed and experimentally validated using
common laboratory animals, then extrapolated to
represent man. A series of differential equations are
used to mathematically describe the absorption, tissue
distribution, metabolism and elimination of a
compound in the body. Once experimentally
validated, a PBPK model will facilitate extrapolation
across different routes of exposure, from high-to-low
doses, and among animal species (Andersen et al.
1993). Thus, by monitoring exhaled breath for a
particular compound, the estimated exposure and
target tissue dose can be determined.
Application in Dermal Bioavailability Studies
The combination of real-time breath analysis and
PBPK modeling provides an opportunity to follow the
changing kinetics of the uptake, distribution, and
elimination phases of a compound throughout a
dermal exposure. The sensitivity of the mass
spectrometer for exhaled-breath analysis has been
pivotal in enabling studies wherein human volunteers
are exposed to low levels of compounds for short
periods of time. For example, a method was
developed to determine dermal absorption of solvents
under non-steady-state conditions by monitoring
exhaled air using real-time breath analysis in rats,
monkeys, and humans. Dermal patch systems were
developed to expose experimental animals and human
volunteers to volatile chemicals in soil and water
matrices under occluded and non-occluded conditions.
The occluded system consisted of a hand-blown glass
cell with a needle-hole opening in the top to allow
addition of the dosing solution. The needle hole was
sealed using silicone following addition of the test
27
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Rat Kp = 0.25 cm/hr
1.5 2.0 2.5 3.0 3.5 4.0 4.5 5.0
Human Kp = 0.0063 cm/hr
Figure 2. Comparison of PBKB model predictions (lines) and exhaled breath (human) or chamber concentration (rat) following
dermal exposure to aqueous methyl chloroform. The human subject was a 29-year old Caucasian man, 95.3-kg body weight,
195.6-cm height, and 22.2-% body fat. Data are averaged after every 1-minute interval (Poet et al. 2000).
material. For non-occluded exposures, glass cells
were constructed with an upper chamber separated
from the matrix by a semi-permeable frit. The upper
chamber was packed with activated charcoal to trap
volatilized test materials. Regardless of exposure
system, the cells were attached to the forearms of
human volunteers (two per arm) or a clipper-shaved
area on the lower back of the rat using a
cyanoacrylate adhesive.
A number of comparisons of dermal absorption have
been conducted, including occlusion versus non-
occlusion, soil versus water matrices, and species
differences. For example, Figure 2 compares rat and
human dermal exposures to aqueous methyl
chloroform under occluded conditions. Despite the
similarity between the rat and human exposure
concentrations (0.1% and 0.12%, respectively) and
exposure surface areas (1.7% rat and 3% human),
there were clear differences in both the time to peak
exhalation and the amount of compound exhaled (area
under the curve) between rats and humans. The
permeability constant (Kp) calculated from these
exhaled-breath data using the PBPK model was
roughly 40 times higher in the rat than that calculated
for the human (Kp = 0.25 cm/hr versus 0.0063 cm/hr).
Discussion
Exposure assessment is a critical component of
industrial hygiene and worker health protection
programs. Given today's diverse work environments,
new and innovative methodologies for exposure
assessment are needed in order to fully understand
the potential health risks of the individual worker.
Routine analysis of exhaled breath may be ideal for
tracking occupational exposures, particularly with the
advent of field-deployable standardized
methodologies. Exhaled breath analysis offers a
number of advantages, including being non-invasive,
is applicable to a number of compounds, avoids the
handling of potentially infectious biological samples,
and can be analyzed easily and quickly using the
methodology described here. Furthermore, the
system described here goes well beyond traditional
industrial hygiene exposure assessment
methodologies by employing PBPK models to
understand the relationship between exposure and
internal, target tissue dose.
The studies described here have focused on the
utilization of exhaled breath analysis following
controlled dermal exposures to understand the
contribution of the dermal pathway on total exposure.
These studies have illustrated that the methodology is
sufficiently sensitive to successfully measure low-level
exposures, or exposures to poorly absorbed
compounds in humans. The field portability of the
system has the potential to place the exposure
assessment methodology in situations where it can be
used to conduct occupational and environmental
exposure assessments to volatile compounds.
References
Andersen, M.E., Krewski, D., and Withey, J.R. (1993).
Physiological pharmacokinetics and cancer risk
assessment. Cancer Letters. 69: 1-14.
Poet, T.S., Thrall, K.D., Corley, R.A., Hui, X., Maibach,
H.I., and Wester, R.C. (2000). Utility of real time
breath analysis and physiologically based
pharmacokinetic modeling to determine the
percutaneous absorption of methyl chloroform in rats
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and humans. Toxicological Sciences. 54:42-51. and evaluation of a breath-analysis system for
biological monitoring of volatile compounds. American
Thrall, K.D., and Kenny, D.V. (1996). Evaluation of a Industrial Hygiene Association Journal. 62(1): 28-35.
carbon tetrachloride physiologically based
pharmacokinetic model using real-time breath-analysis The work described in this paper was not funded by the
monitoring in the rat. Inhalation Toxicology. 8(3): 251- United States Environmental Protection Agency and,
261 therefore, the contents do not necessarily reflect the views of
the Agency and no official endorsement should be inferred.
Thrall, K.D., Callahan, P.J., Weitz, K.K., Edwards,
J.A., Brinkman, M.C., and Kenny, D.V. (2001). Design
29
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Appendix D-2
Odor, Irritation, and Health Symptoms from Biosolids Land Applications
Pamela Dalton, PhD, MPH
Monell Chemical Senses Center
Malodors from biosolids comprise one of the chief
complaints that are regularly lodged against land
applications, particularly those occurring in close
proximity to residential communities. In addition to
generating annoyance complaints, however, malodor
perception often triggers reports of health symptoms
among exposed individuals. Distinguishing between
exposures to the volatiles from land applications that
elicit ocular or upper respiratory sensory irritation or
health symptoms from those that elicit only odor-
mediated annoyance is a key component in establishing
and enforcing exposure guidelines that are protective of
residents in nearby communities. Laboratory studies
documenting exposure concentrations and multiple
levels of response can help to establish thresholds for
annoyance, irritation and health symptoms. Such
studies can also help differentiate between the degree to
which complaints and symptoms are mediated by
psychological rather than physiological factors.
However, the successful application of these findings to
practice requires a better understanding of the
relationship between actual community exposures and
response thresholds for each level. This approach
necessitates an increased focus on measuring the
association between the dynamic profile (i.e. intensity,
frequency and duration) for key odorants and irritants in
biosolids emissions and the perception and response of
exposed community residents.
This paper is divided into two broad sections. The first
section addresses the factors which promote adverse
responses to the volatile organic compounds associated
with biosolids land applications while the second section
outlines some key components which should be
included in a monitoring plan to evaluate exposure and
impact of land applications on humans.
A workshop held at Duke University in 1998 (Schiffman
et al., 2001) led to a consensus among attendees that
there were three paradigms or mechanisms by which
volatile organic compounds (VOCs) could generate
health symptoms and adverse responses: (1) The VOCs
emitted from land applications could individually or in
combination produce ocular and/or upper airway
irritation, (2) the VOCs could produce objectionable
odors which themselves could elicit annoyance, stress
and perception of health risks and (3) the VOCs may
simply co-occur with bioaerosols and/or particulates,
which themselves are eliciting the symptoms. This
paper will focus solely on the first two mechanisms for
VOC-induced complaints and examine the evidence for
each one in turn.
VOCs, Odor and Sensory Irritation
As odorant concentration increases, the sensory effects
experienced typically occur in a predictable sequence.
At low concentrations, the presence of an odor can be
detected against a clean air background, although its
quality may not be apparent. The recognition threshold
for an odorant is typically three times the detection
threshold. With increasing concentrations, an
undesirable odor will often bring about annoyance
and/or intolerance. For most volatile organic
compounds, direct physical effects from an odorant do
not occur until the concentration increases to the point
beyond trigeminal or sensory irritant activation.
Nevertheless, people often report physical symptoms
and irritation at concentrations much lower than the
irritant threshold.
Sensations of odor and upper airway irritation are often
experienced as a unitary phenomenon, principally
because most volatile chemicals have the potential to
activate two separate, yet interrelated, sensory
pathways in the upper respiratory airways: the olfactory
nerve, which gives rise to sensations of odor, and the
trigeminal, glossopharyngeal or vagal nerves which give
rise to temporary burning, stinging, tingling or painful
30
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sensations in the eyes and upper airways (Doty et al.,
2004). Chemical stimulation of the trigeminal nerve
(known as chemesthesis) often combines with
stimulation of the olfactory nerve to produce sensations
that form an overall perception of a chemical. For
example, low concentrations of ammonia produce a
distinct odor; however, higher concentrations may also
elicit a mucosal burning or tingling, which is the
chemesthetic or irritant component of perception. Most
chemicals at sufficiently high concentrations are capable
of eliciting upper respiratory tract irritation in addition to
odor sensations. Because these two sensory pathways
(olfaction and chemesthesis) can be activated by a
single chemical stimulus, people often experience and
report odor and irritation as a unitary perception. For
purposes of evaluating the irritant potential of a
chemical, this confusion can invalidate self-report
methods, such as symptom questionnaires or even
ratings of a chemical's irritancy.
The sensory detectability, irritant potential and quality of
land application emissions can be determined in a
variety of ways both in the laboratory and the field. For
example, in the laboratory, bagged samples of air taken
from various onsite and offsite locations can be fed into
air-dilution olfactometers and presented to panelists for
forced-choice detection of the presence or absence of
odor. To measure irritation thresholds that are not
confounded by simple odor detection, a method known
as nasal or ocular lateralization is used. This technique
exploits the fact that the presence of a pure odorant
cannot be localized to the left or right nostril or the left or
right eye, but a chemical capable of stimulating
trigeminal receptors will clearly provide a sensation in
the nasal or ocular mucosa which can be localized
(Wysocki et al., 1997; Doty et al., 2004).
For evaluation in the field, an instrument known as the
Nasal Ranger™ can be utilized to actively dilute ambient
air samples in a series of known dilution ratios which are
then compared with clean filtered air (McGinley and
McGinely, 2004). The dilution ratio at which the
individual can reliably discriminate the 'stimulus' air from
the clean filtered air is the odor threshold. In both cases,
this is reported as the dilutions to threshold ratio for the
emission. Although not explicitly designed for this
purpose, it is possible that a device like the Nasal
Ranger™ could be adapted to do field evaluations of the
lateralization potential (which nostril or eye is being
stimulated) of real-time emissions. Such an adaptation
combines the advantage of onsite testing with the
sophistication of the lateralization technique for
determining whether emissions reach the concentration
necessary to elicit sensory irritation.
Monitoring VOCs and Annoyance
Often the odors associated with land application of
biosolids, become significant community issues.
Exposed residents may claim that the odors are making
them ill. Research has shown that for some period of
time following land application, malodors are typically
present at concentrations greater than those capable of
generating odor perception, but at offsite locations,
frequently fall well below those concentrations capable
of generating sensory irritation or other acute health
effects. The challenge then is to identify the reasons
behind community reactions to odors and to understand
whether the volatile odor chemicals (i.e. odorants) elicit
health symptoms through direct physiological mediation
or through psychological or stress mechanisms.
One way to think about the sensory determinants of
what makes an odor annoying is the acronym FIDO -
the Frequency of an odor, the Intensity at which it
occurs, its Duration and its Offensiveness. The first three
characteristics can be measured analytically with
instruments. However, to understand Offensiveness, it is
necessary to measure people's reactions. This requires
understanding not only the primary sensory attributes of
an odor, but non-sensory attributes, or the cognitive and
emotional factors that can produce heightened odor
awareness and annoyance.
Frequency. Frequency of exposure can by itself alter
sensitivity. While it is well acknowledged that
continuous exposure to a chemical at a fairly steady
concentration leads to a decreased intensity or
adaptation, most of the odors from land applications are
likely to be intermittent in nature and varying in
concentration. In studies that evaluated the impact of
intermittent exposure to low-level odors via threshold
testing, it was found that females of reproductive age
exhibited dramatically increased sensitivity to the odor to
which they were exposed, while males, pre-pubescent
females and post-menopausal females did not change
sensitivity (Diamond et al., 2005; Dalton et al., 2002). In
the real world, intermittent exposure to VOCs from land
emissions, especially at very low levels, may serve to
increase their detectability, even when emissions wane.
Intensity. Measuring the number of dilutions to odorant
threshold is important to establish the concentration at
which an odorant will become detectable, but provides
little information about how increasing concentration will
affect stimulus intensity. Although many odorous
compounds become detectable at approximately the
same physical concentration, increases in physical
concentration for one odorant may result in much larger
changes in perceived intensity than do the same
increases in physical concentration for another odorant.
Thus, the shape of the psychophysical function and the
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slope are important indicators of how intensity (and
perhaps how annoyance) will change with concentration,
and are not the same for all odorant chemicals that may
be found in land applications.
Duration. The duration of exposure is also critically
important when evaluating the irritant potential of a
volatile chemical. Increased duration of nasal exposure
to ammonia, for example, has been shown to also
increase the perceived irritant intensity, due to a
phenomenon known as temporal integration (Wise et al,
2005). It is likely that many other irritants exhibit similar
patterns of integration, thereby placing important limits
on the ability to extrapolate from evaluation of irritants
for very brief durations (i.e., seconds) to real-world
exposures that may last minutes or hours.
Which Odorous Components to Monitor?
It is also important to recognize that emissions from land
applications comprise a complex mixture of many
different volatiles, some of which have the potential to
contribute to odor or irritant impact more than others.
For this reason, the choice of which volatiles to monitor
is critical in order to understand the sensory impact of
any emissions which migrate offsite. The most typical
compounds measured from biosolids emissions are
hydrogen sulfide (H2S) and ammonia; H2S has a readily
detectable and objectionable odor at very low
concentrations and is often present at a high volume
while ammonia can contribute to the irritation impact of
emissions. However, due to the highly heterogeneous
nature of biosolids, there are many other malodorous
compounds which may be emitted during and after land
applications and which may contribute substantially to
the odor or irritant impact. Both H2S and ammonia have
fairly high vapor pressure and while they readily diffuse
into air and may well comprise the majority of the early
sensory impact, they are also likely to dissipate more
rapidly than other compounds and thus, prolonged
sensory impact may well be the result of other
compounds (such as amines, indoles) which volatilize
more slowly from the application site.
In the laboratory, characterizing the sensory impact from
biosolids via methods such as gas chromatography/
olfactometry (Preti et al., 1993; Bazemore et al., 2000),
in which human reports of odor qualities in a complex
mixture are linked to the output of a gas chromatograph
column separation and the subsequent identification, is
important for understanding the sensory potency of any
biosolids mixture. In the field, real-time measurements
of other compounds with high odor potential should be
considered. However, if emissions measurements are
confined to sentinel compounds, such as H2S and
ammonia, then continuous monitoring should be
augmented by regular and frequent evaluation by human
detectors using Nasal Ranger™ technology, to ensure
that compounds other than those being monitored are
not eliciting malodor perception offsite.
To summarize, the choice of when, where and how
frequently to measure and the selection of which key
components to measure are important features of any
comprehensive monitoring plan for assessing the
annoyance impact of biosolids land applications on
nearby residents.
Cognitive Factors and Perception of Health Risk
Unfortunately, measuring and finding ways to reduce the
sensory impact of any volatile compounds from land
applications may not always resolve the complaints from
people living or working near the land application site.
The perception of even weak or transient malodors can
also elicit adverse responses via psychogenically-
mediated mechanisms, such as annoyance and stress.
Although the presence of an odor is a signal of chemical
presence, the potency or hedonic nature of an odor
sensation does not correlate with its toxic potential.
Because many malodors can be smelled in minute
concentrations, simply being able to smell the malodor
does not signify that it is present in a harmful
concentration.
Research in our laboratory has shown that people's
reaction to odor and their beliefs about the effects from
odor are influenced by a diverse set of factors, including
personality traits, personal experience and information
or social cues from the community and media. These
factors can increase, or in some cases decrease, a
person's sensitivity and awareness of environmental
odors. In a series of studies, we have demonstrated how
the misperception of the risk from odors actually
changes a person's sensory perception of odor levels
and their perception of well-being (Dalton et al., 1997;
Dalton, 1999).
The results from these studies indicate to us that the
reaction that people have to odors is not simply due to
their sensory impact but is also shaped by the attitudes
and expectations that an individual brings to an odor
experience. In no way do we wish to minimize the
importance of remediating the sensory impact of
emissions as the first step in reducing the level of
community annoyance and complaints. However,
because even small amounts of odorous molecules can
generate odors, reductions of 70-80 percent in odor
concentration can still result in complaints if neighbors
can detect even weak and transient odors and are
concerned about the health impact of the emissions.
Thus, working with communities and neighbors to
provide them with information and to help them
understand the nature of the odors, what they represent
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and their known effects can be a powerful tool to modify
the cognitive factors that often guide and influence
community reaction to odor emissions.
Conclusions
Monitoring programs for evaluating the effect of biosolids
land applications on human health should focus on
closing the data gaps in the following three areas. First,
simultaneous documentation of actual exposure
concentrations and effects at the observer level in
residential communities is a priority. At the present time,
much is known about the emissions at the land
application site and at the fence line, but few studies
have undertaken comprehensive monitoring at the
community level. Second, any such program should
strive to identify the appropriate odorants and potential
irritants for monitoring, which may well be more than just
H2S and ammonia. Finally, response variation within
and across communities should be evaluated in light of
the composition of the biosolids, the temporal factors
(duration and frequency) of exposure and the attitudes
and expectations of the exposed community. These
factors, taken together, can do much to identify and
illuminate the actual and perceived sensory and health
concerns from biosolids land applications.
References
Bazemore, R., Wysocki, C.J., Murray, S., Lawley, H.J.,
and Preti, G. (2000). Amelioration of odorous
components in spent mushroom compost. Journal of
Agricultural and Food Chemistry. 48: 3694-3697.
Dalton, P. (1999). Cognitive influences on health
symptoms from acute chemical exposure. Health
Psychology. 18: 579-590.
Dalton, P., Doolittle, N., and Breslin, P.A.S. (2002).
Gender-specific induction of ultra-sensitivity to odors.
Nature Neuroscience. 5: 199-200.
Dalton, P., Wysocki, C.J., Brody, M.J., and Lawley, H.J.
(1997). The influence of cognitive bias on the perceived
odor, irritation and health symptoms from chemical
exposure. International Archives of Occupational and
Environmental Health. 69: 407-417.
Diamond, J., Dalton, P., Doolittle, N., and Breslin, P.A.
(2005). Gender-specific Olfactory Sensitization:
Hormonal and Cognitive Influences. Chemical Senses.
SOSuppI 1:1224-1225.
Doty, R.L., Cometto-Muniz, J.E., Jalowayski, A.A.,
Dalton, P., Kendal-Reed, M., and Hodgson, M. (2004).
Assessment of upper respiratory tract and ocular
irritative effects of volatile chemicals in humans. Critical
Reviews in Toxicology. 34: 85-142.
McGinley, M.A. and McGinley, C.M. (2004). Comparison
of field olfactometers in a controlled chamber using
hydrogen sulfide as the test odorant. Water Science and
Technology. 50: 75-82.
Preti, G., Gittelman, T.S., Staudte, P.B., and Luitweiler,
P. (1993). Letting the nose lead the way. Malodorous
components in drinking water. Analytical Chemistry. 65:
699A-702A.
Schiffman, S.S., Walker, J.M., Dalton, P., Lorig, T.S.,
Raymer, J.H., and Shusterman, D. (2001). Potential
health effects of odor from animal operations,
wastewater treatment, and recycling of byproducts.
Journal ofAgromedicine. 7: 7-81.
Wise, P.M., Canty, T.M., and Wysocki, C.J. (2005).
Temporal integration of nasal irritation from ammonia at
threshold and supra-threshold levels. Toxicological
Sciences. 87: 223-231.
Wysocki, C.J., Dalton, P., Brody, M.J., and Lawley, H.J.
(1997). Acetone odor and irritation thresholds obtained
from acetone-exposed factory workers and from control
(occupationally non-exposed) subjects. American
Industrial Hygiene Association Journal. 58: 704-712.
The work described in this paper was not funded by the United
States Environmental Protection Agency and, therefore, the
contents do not necessarily reflect the views of the Agency and
no official endorsement should be inferred.
33
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Appendix D-3
Detection and Measurement of Odor, Ammonia, and Hydrogen Sulfide
Emissions as part of USEPA Biosolids Land Application Research Project
Robert H. Forbes, Jr., P.E.
CH2M HILL, Inc.
Abstract
CH2M HILL participated in a research project entitled
"Multimedia Sampling at Biosolids Land Application
Sites" as a consultant to Battelle Memorial Institute in
the fall of 2004. The overall goal of the research was to
advance the science of air, soil, and water quality
measurements associated with land application of
biosolids to agricultural sites. CH2M HILL's role was to
detect and characterize odors from the site, and to
measure the concentrations of two volatile gases
commonly associated with biosolids land application,
ammonia and hydrogen sulfide.
Background odor levels prior to biosolids application
(Day -1) were measured as "trace" by the onsite field
receptors, while the more sensitive, offsite odor panel
measured the odor levels at 60-90 dilutions-to-threshold
(D/T). This is indicative of the sensitivity differences
between onsite and offsite odor measurements. Odors
from ground-level flux chambers onsite increased
substantially after biosolids application (Day 0) and the
following day (Day 1) as measured by the offsite odor
panel. Odors measured in the field increased on Day 0
after application as expected, but did not increase
significantly above Day 0 levels on Day 1. Odors
measured by the field crew began subsiding on Day 2
and returned to background levels at all sampling
locations by Day 4.
Both ammonia and hydrogen sulfide were detected at
fairly significant concentrations (15 ppmv and 0.17
ppmv, respectively) from the flux chamber exhaust soon
after biosolids application on Day 0, but their
concentrations at five feet above ground level (where
most field measurements were taken) were much lower.
Their concentrations had subsided further at all locations
by Day 1 and Day 2, returning to background levels by
Day 4.
It was concluded that most odors associated with
biosolids land application are not from ammonia and
hydrogen sulfide, but more likely are from reduced
organic sulfur compounds such as methyl mercaptan
and dimethyl sulfide, along with nitrogen-based organic
compounds such as trimethyl amine, indole, and skatole.
Chemical measurements made by others during the field
study support these conclusions.
Introduction
CH2M HILL participated in a research project entitled
"Multimedia Sampling at Biosolids Land Application
Sites" as a consultant to Battelle Memorial Institute in
the fall of 2004. The overall goal of the research was to
advance the science of air, soil, and water quality
measurements associated with land application of
biosolids to agricultural sites. CH2M HILL's role was to
detect and characterize odors from the site, and to
measure the concentrations of two volatile gases
commonly associated biosolids land application,
ammonia and hydrogen sulfide. Field work began on
the day before the biosolids application event (Sept. 29,
2004 = Day -1) and continued through the day of
application (Sept. 30, 2004 = Day 0), followed by Days
1,2, and 4.
Materials and Methods
Odor measurements onsite were made on all five field-
sampling days using three hand-held olfactometers
called Nasal Rangers™, and the field odor levels were
compared with odor measurements made by an offsite
odor panel on three of the sampling days (Day -1, Day 0,
and Day 1). Field measurements of ammonia were
performed using chemical sensory tubes manufactured
by Drager™ coupled with a calibrated hand-held
34
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vacuum pump, also by Drager™. Field measurements
of hydrogen sulfide were made using a Jerome™ type
gold-film analyzer as manufactured by Arizona
Instruments, with an internal sample pump and a
detection limit of 0.001 parts per million by volume
(ppmv).
Three air samples were taken from onsite flux chambers
installed by other researchers (McConnell, 2005),
pumped into Tedlar air-sample bags, and shipped
overnight to St. Croix Sensory Laboratories in St. Croix,
MN, where a certified odor panel was used to conduct
offsite odor analyses according to a standard and
accepted procedure for measuring the intensity of odors.
In this procedure, each odor panelist tries to distinguish
a diluted odor sample from two other samples that are
odor-free blanks. The sample air is mixed with pure,
odor-free air at pre-set dilutions. The sample's dilution
level at which an odor is barely detected by the panelist
is called the "detection threshold" (DT) of that odor
sample. The intensity of the odor sample itself is
measured in terms of the number of dilutions that were
combined in the sample at which the DT was measured,
in units expressed as dilutions-to-threshold (D/T). A
seven person panel is used in certified, offsite odor
testing, and the measurements by different panelists are
averaged to arrive at the reported odor DT in odor units
of D/T.
Onsite odor measurements taken with the Nasal
Ranger™ olfactometer are intended to mimic
measurements made by an offsite odor panel, with
results of both methods reported in similar odor units
(D/T). The offsite odor-panel measurements are usually
much more sensitive than onsite measurements, but the
relative differences among odor samples should show
similar trends with either onsite or offsite odor
measurements.
Results
Results of daily odor measurements were compared and
trended. Background levels prior to biosolids application
(Day -1) were measured as "trace" by the onsite field
receptors, while the more sensitive, offsite odor panel
measured the odor levels at 60-90 dilutions-to-threshold
(D/T). This is indicative of the sensitivity differences
between onsite and offsite odor measurements.
Odors from ground-level flux chambers increased
substantially after biosolids application (Day 0) and the
following day (Day 1) as measured by the offsite odor
panel. On the flux-chamber sample that was taken on
Day 0 immediately after the land-application event, the
offsite odor panel measured odor intensities in the range
of 500 to 1,000 dilutions-to-threshold (D/T). The offsite
odor panel reported even higher odor levels from flux-
chamber samples taken on Day 1 approximately 24
hours after land application, with their results ranging
from 2500 to 6100 D/T.
Offsite odor analyses by a certified odor panel are quite
expensive, however, so the three flux-chamber samples
taken on Day -1, Day 0, and Day 1 were the only
samples to be shipped to St. Croix Sensory Laboratories
and analyzed there.
The onsite odor panel measured odor levels exceeding
30 D/T from the flux chamber exhaust sample on Day 0
(about an odor of magnitude less than the 500 D/T odor
measurements by the offsite odor panel). The onsite
odor panel also measured odor levels in the range of 15-
30 D/T from ambient air onsite and immediately
downwind. At locations immediately upwind of the site
on Day 0, the onsite odor panelists measured odors in
the range of 2-7 D/T.
On the day after biosolids application (Day 1) the onsite
odor panelists once again measured odors from the flux
chamber exceeding 30 D/T, while the offsite panel
reported even higher odor levels. These results indicate
that there may be some acclimation and decreased
sensitivities to odor levels by onsite odor panels, as
compared with the more sensitive offsite odor panels.
Ambient odor levels measured by the onsite field panel
were in the range of 15 D/T onsite and immediately
downwind on Day 1, while the onsite panelists could not
detect any odors above background upwind of the site
on Day 1.
Ambient odor levels as measured by the onsite panel
began subsiding on Day 2 to a level of 15 D/T from the
flux chamber exhaust. Odors were barely detected at
locations downwind of the site on Day 2, and were
undetected at all locations upwind of the site. Odor
levels as measured by the onsite panelists had returned
to background concentrations at all sampling locations
by Day 4.
Ammonia was not detected in any of the background
measurements taken on Day -1. Hydrogen sulfide was
detected in the Day -1 background measurements at
concentrations of 0.002 to 0.005 ppmv. The hydrogen
sulfide measurements are at least partially attributed to
the exhaust gases of the biosolids-applicator and
sampling vehicles, which were running without biosolids
on the day prior to biosolids application (Day -1).
Both ammonia and hydrogen sulfide were detected at
fairly significant concentrations (15 ppmv and 0.17
ppmv, respectively) from the flux chamber exhaust
samples soon after biosolids application on Day 0. The
concentrations of ammonia and hydrogen sulfide at five
feet above ground level (where most field
35
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measurements were taken) were much lower, however.
Their concentrations had subsided further at all locations
by Day 1 and Day 2, and concentrations of both
ammonia and hydrogen sulfide had returned to
background levels by Day 4.
At least one other researcher at the experimental site
detected ammonia using the open-path integrated,
optical remote sensing techniques (Harris, 2005), which
utilizes absorption infrared spectroscopy. In that
research, an ammonia plume was measured during and
immediately after biosolids application, but it dropped
rapidly to non-detect levels within three hours after
application. The results of those ammonia
measurements were in the same ranges as results
obtained in this study using Drager™ chemical sensory
tubes.
Conclusions
It was concluded that ammonia is a source of odors only
during and immediately after biosolids application, to
receptors that are either onsite or in close proximity to
the application site. Ammonia is generally not detected
at any appreciable distance from the site because it has
a high detection threshold and it disperses very rapidly
upon volatilization.
Hydrogen sulfide may be detected in background
samples due to its presence in vehicle exhaust, and it
also has sources in livestock operations (chickens, cattle
and hogs, for example) that are often found in rural
areas. Generally, the increase in hydrogen sulfide over
background levels due to biosolids application is very
slight, and hydrogen sulfide is not generally a significant
contributor to odors from most biosolids application
activities.
It was concluded, based on the results of this study, that
most odors associated with biosolids land application
are not from ammonia and hydrogen sulfide, but more
likely are from reduced organic sulfur compounds such
as methyl mercaptan and dimethyl sulfide, along with
nitrogen-based organic compounds such as trimethyl
amine, indole, and skatole. Chemical measurements
made by others during the field study (McConnell, 2005)
tend to support these conclusions.
References
McConnell, L.L. Preliminary summary of odorant
chemical analysis in headspace and flux chamber
samples and Polybrominated Diphenyl Ether analysis.
USDA presentation to Biosolids Information Sharing
Group, December 2005.
Harris, D.B. Open-path FTIR measurement of gaseous
emissions from biosolids application to an agricultural
field. USEPA NRMRL presentation to Biosolids
Information Sharing Group, December 2005.
Although the work described in this paper was funded by the
United States Environmental Protection Agency under contract
number 68-C-00-159 to Battelle, the contents do not
necessarily reflect the views of the Agency and no official
endorsement should be inferred.
Mention of trade names or commercial products does not
constitute endorsement or recommendation by EPA for use.
36
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Appendix D-4
Community and Occupational Risk from Bioaerosols during Land Application
of Biosolids
Ian L. Pepper
The University of Arizona
During land application of Class B biosolids there is the
potential for aerosolization of human pathogenic
microorganisms that could adversely impact human
health and welfare. Recently the University of Arizona
conducted a major study evaluating the community and
occupational risk from bioaerosols during land
application of biosolids. In addition, the incidence of
aerosolized endotoxin was also evaluated. For
community risk, aerosol samples were collected for two
years from land application sites located at various
locations throughout the U.S., representing different
climatic conditions and different application practices.
Land application practices involved the use of liquid
biosolids spray and "cake" biosolids applicators
depending on location. Bioaerosols were collected via
the use of six SKC BioSamplers®, impinging air at a rate
of 12.5 L/min for a total of 20 minutes. Samples were
collected from both downwind of land application and
background sites from distances ranging between 2 m
and 70 m downwind. Microbial concentrations were
measured within these aerosols, including:
heterotrophic plate count bacteria (HPC), coliphage,
Clostridium perfringens, total conforms, Escherichia coli,
endotoxin (lipopolysaccharide), enteroviruses, norovirus,
and Hepatitis A virus (HAV). In addition a model was
developed to predict viral transport. Overall, the levels of
aerosolized indicator bacteria and phage were at or
below detection limits. Three samples were positive for
the presence of norovirus viral RNA via reverse
transcriptase polymerase chain reaction, although their
viability was unable to be determined based on current
available techniques.
and
the
Community risk assessments were conducted using an
empirically derived transport model. (Brooks et al.,
2005). The assumptions used in the risk assessment
were:
• 105 phage/g biosolid
• 0.1 virus/g biosolid (assume Coxsackie)
• virus:phage = 1:1000000
• using the seeded water model for phage
adjusting for biosolid phage concentration,
estimated phage number at 100 ft is 7.16 x 10~1
phage/m3
• therefore estimated virus concentration from land
application of biosolids at 1 00 ft = 7.1 6 x 1 0"7/m3
• assume 0.1 coxsackie virus/g biosolid
• distance from site = 1 00 ft
• exposure = 1 hr
• dose = 5.94 E-07 virus
• using one-hit exponential model (P = 1-erN)
Risk = 1 .50 E-08
Similar Risk for 8-hr exposure = 1 .2
E-07
For a more conservative approach
• assume 100 viruses/g biosolid
• estimated virus concentration
from
land
application of biosolids at 100 ft = 7.16 x io~4/m3
• assume 100 virus/g biosolid
One-hour Risk = 1.5 E-05
8-hour Risk = 1.2E-04
Figure 1 shows risks determined assuming different viral
concentrations within biosolids at different distances
from the land application site. Exposure times are also
varied.
37
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One Time Risk as per
Distance from. Point Source
,„ •-•)«*<
_§ I.ME-OI ^
~ I.ME-02
*^ i f^C fl^S
***• i y JC "¥*/
H 1C3E-W
u IOE-C5 JS.
g s ODE-OS i ^^^
29 40 « 89 100 120 140 ISO
201
0:of!tKfal till;
scoE-ii -
O.I «u$l;fir«ip«i«
1 i atus es l!if«i|»Mie
ID aus es ttreip-Mwe
O.I nus 1hr«iposur«
Ksanct from point jmj
Figure 1. Risk assessments generated at set distances from the land application site assuming different viral inputs and
exposures times
For occupational risk, three experiments were conducted
to characterize the concentration of microorganisms in
biosolids, the plume of aerosols created during land
application of biosolids and the occupational risk of
infection due to pathogens aerosolized during land
application of biosolids in the United States. In all, more
than 300 air samples were collected immediately
downwind of biosolids applications throughout the
United States using liquid impingers, and more than 100
air-samplers were collected downwind of microbially
seeded, land applied water, which served as a
conservative model system of aerosol generation. The
novel model system made it possible to calculate the
flux of microorganisms through a virtual plane defined by
air samplers in vertical and horizontal arrays, located
immediately downwind of a passing spray applicator.
The rate of aerosolization during land application of
biosolids near Tucson, Arizona, was calculated to be
less than 33 plaque forming units (PFU) of coliphage
and 10 colony forming units (CPU) of coliform bacteria
per meter traveled by the spray applicator (Tanner et al.,
2005). Rates of aerosolization from the model system
were shown to be much greater. Exposure duration was
shown to be brief and limited to the time when biosolids
were actually in the air. To assess the risk to
occupational health from bioaerosols generated during
land application of biosolids, coliform bacteria,
coliphages, and heterotrophic plate count (HPC)
bacteria were enumerated from air and biosolids at 10
land application sites throughout the nation. The method
of land application strongly influenced aerosolization,
while relative humidity, temperature and wind speed
showed limited correlation to concentrations of fecal
indicator microorganisms in air. Occupational risks of
infection and illness from aerosolized Salmonella and
enteroviruses were calculated for a variety of land
application scenarios.
The assumptions used in the risk assessment were:
• Worker on land application site 8 hours/work day
• 251 work days/year
• Tractor cab air filter 50% efficient in removing
aerosolized microorganisms
• Operator downwind of biosolids 50% of the time
• No inactivation of aerosolized microbe
• Concentration of pathogens and indicators in air
will be a reflection of pathogens and indicators in
biosolids
• Therefore concentrations of conforms in air can be
used to estimate concentration of Salmonella in
air, and
• Concentration of phage in air can be used to
estimate human virus concentrations in air
• Breathing rate = 10 m3/8 hours (light activity)
• 100 to 1000- Salmonella and 0.1 to 10 human
virus/g of biosolids
• 10% of Salmonella that are inhaled are
subsequently ingested (no dose response
available for inhalation of Salmonella)
• Human virus is Coxsackievirus A21 (dose
response for inhalation available)
38
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Where:
The probability of infection from ingestion of pathogenic
bacteria was calculated using the Beta-Poisson
Distribution model.
Here Pday = 1 - [1 + (d / N50) (21/a -1)]'°
Pday is the probability of infection per workday
d is the number of pathogens ingested per day
(10% of pathogens inhaled)
N50 is the dose at which half of subjects are
infected with a particular pathogen
a is a parameter which describes the
distribution of infection
Summary
The probability of infection from the inhalation of virus
was calculated using the Single-hit Exponential
Distribution Model
-rd
Here, Pday = 1-e
Where,
r is a parameter defining the probability of a
single organism initiating infection
d is the number of pathogens inhaled per day
The annual risk of infection was calculated from the daily
risk of infection, assuming 251 days per year of
occupational exposure, using the following formula:
Here: Pyear=1-(1-Pday)251
Calculated occupational risks are shown in Tables 1 and
2 assuming different viral and bacterial concentrations
within biosolids.
Overall risk of infection from bioaerosols resulting
from land application is low.
Duration of exposure during land application is
very discrete.
Occupational risk is greater than community risk
due to enhanced exposure, but still low.
Community risk is insignificant.
The greatest risk to occupational workers occurs
during loading of biosolids.
For community and occupational risk, there is less
risk due to bacteria than virus.
Application method influences aerosolization
rates.
Environmental factors do not influence
aerosolization rates
References
Brooks, J.P., Tanner, B.D., Gerba, C.P., Haas, D.N., and
Pepper, I.L. (2005). Estimation of bioaerosol risk of
infection to residents adjacent to a land applied biosolids
site using an empirically derived transport model.
Journal of Applied Microbiology. 98: 397-405.
Tanner, B.D., Brooks, J.P., Haas, C.N., Gerba, C.P., and
Pepper, I.L. (2005). Bioaerosol emission rate and plume
characteristics during land application of liquid Class B
biosolids. Environmental Science and Technology. 39:
1584-1590.
The work described in this paper was not funded by the United
States Environmental Protection Agency and, therefore, the
contents do not necessarily reflect the views of the Agency and
no official endorsement should be inferred.
Table 1: Occupational risk: annual risk of infection due to inhalation of coxsackievirus A-21
Enterovirus/g biosolids
10
1
0.1
Loading
Land Application
1.9 x 10"
2.1 x 10
-2
7.5x 10
-2
7.8 x 10
-3
2.1 x 10
-3
7.8x 10
-4
Table 2: Occupational risk: annual risk of infection from non-typhi Salmonella assuming 10% of inhaled Salmonella are ingested
Salmonella/ g biosolids
1000
100
Loading
Spreader
1.3x 10
-3
1.3 x 10
-4
9.8 x 10
-5
9.8x 10
,-6
39
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Appendix D-5
Lessons Learned Regarding the Use of an Impinger for Collecting Airborne
Bacteria during a Biosolids Application Field Study
Edwin F. Earth, PhD, P.E., C.I.H.
USEPA-NRMRL
Abstract
The National Risk Management Research Laboratory
(NRMRL) of the USEPA performed laboratory wind
tunnel studies as well as large field studies to evaluate
specific bioaerosol components (bacteria, fungi,
endotoxin, p-d glucan) that may be associated with
various practices for managing semi-solids such as
biosolids or sediments (contaminated by combined
sewer overflows). The wind tunnel studies indicated
limitations involving the impingement collection method.
Modifications to common practices for impingement
collection procedures, gained from the wind tunnel
studies, were implemented into the design of the
bioaerosol sampling collection plan for a large field study
involving the land application of biosolids to increase the
likelihood that stress-sensitive bacteria (Gram-negative)
could be collected and detected. These modified
procedures included: covering the impinger with
aluminum foil to block ultra-violet radiation transmission
during collection; periodic washing of the inlet neck
during collection to prevent drying of the biological mass
that may collect on the inlet neck during collection; and a
final rinse step of the inlet neck and jet nozzles after
collection.
Introduction
Various sampling methods are available to collect
airborne bacteria. Interpreting data from any of these
methods for use in a human exposure assessment is
difficult since the flow rate and mechanisms for particle
collection of a biological sampling device may be
different from the physiology and particle deposition of
the human pulmonary system. Furthermore, some of
these sampling devices are relatively large, making it
impractical to collect air samples within the personal
breathing zone of an individual.
The survival of bacteria in air depends upon physical
and chemical factors of the particle such as the particle
size and membrane components. Environmental factors
also play a role in survival in air such as relative
humidity, evaporation rate, temperature, transport time,
and ultra-violet radiation. In addition, an "open air factor"
also reduces viability (Cox et al., 1973). In contradiction,
bacteria have been known to travel long distances,
across oceans, if ultra-violet radiation is blocked by
particulate matter (Griffin et al., 2002).
Traditional bioaerosol sampling methods include
filtration, impingement, and impaction. The advantages
of the impingement method for collecting viable
microorganisms may include the possibility of longer
sampling times (depending upon the collection fluid) to
more accurately assess the personal exposure to
bioaerosols when a person spends a significant period
of time in a specific environment (Lin et al., 1999), less
susceptibility to collection medium overload, and an inlet
parallel to the air stream. In addition, the collection of
the bacteria into a fluid allows the flexibility to split the
collection fluid into several aliquots for various types of
analysis other than bacteria including endotoxin
(Duchaine et al., 2001), viral (Agranovski et al., 2004),
and molecular methods (Angenent et al., 2005).
Disadvantages of this collection method include delicate
sampler device handling procedures, and more difficulty
in setting-up and utilizing in the field relative to other
bioaerosol sampling equipment devices.
Bacterial enumeration techniques included filtration/
plating of the impinger fluid or a spread plate method
used in other bioaerosol impinger studies (Lin et al.,
1999). Even with high collection efficiencies of airborne
40
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bacteria, assays for individual microorganisms may
result in low recovery. Microbial ecology studies have
shown the culturability of microorganisms is low
compared to actual counts in many environmental
settings (Fabbian et al., 2004). For example, the
recovery efficiency for S. aureus seeded in a biosolids
sample was 8.7% (Rusin et al., 2003). In another
bioaerosol study, less than 10% of the aerosolized
bacteria were capable of forming visible colonies with
culture techniques (Heidelberg et al., 1997).
Materials and Methods
Laboratory Wind Tunnel Studies
The evaluation of the impingement collection procedure
consisted of several laboratory trials that were
completed prior to a large field trial involving biosolids
application. For the laboratory trials, a 0.3 m x 0.3 m x
3.6 m (1.0 ft x 1.0 ft x 12.0 ft) wind tunnel was used to
evaluate various bioaerosol sampling methods. Three
BioSampler® impingers (SKC Inc., Eighty Four, PA) were
located 0.9 m (3.0 ft) downwind of the source area in the
wind tunnel. The source area contained various solution
concentrations of a stress-sensitive organism, E. coli, in
a 1000 ml beaker. The bacteria were aerosolized from
the beaker by bubble aeration and mechanical mixing.
The velocity of the filtered air in the wind tunnel
approximated 0.75 m (2.5 ft)/ sec.
Three sets of trials (initial, continuation, threshold) using
E. coli (ATCC 25922), a fecal coliform bacterium of
interest for biologically contaminated sediment, were
performed to develop an efficient collection procedure
for the impingers for collecting stress-sensitive bacteria
in the field.
Two types of impingers were considered for the studies.
The design and specifications of the BioSampler®
impinger include an inlet neck, collection body, and
collection vial. This more recent design is similar to the
All-Glass Impinger (AGI-30), which has been available
for several years. A major difference between these two
impinger types is that particles impinge into the
collection fluid at 90 degrees with the AGI-30, while the
combination of impaction and centrifugal motion may
result in less re-aerosolization of particles from the
BioSampler® (Lin et al., 2000). Other studies with the
BioSampler® have shown nearly 100% collection
efficiency for a wide particle (non-biological) range,
decreasing to approximately 90% for 0.5 urn particles
and to 70% for 0.3 urn particles (SKC, 2004; Lin et al.,
2000). The collection body has a critical orifice in each
of the three jet nozzles that result in a flow rate of
approximately 12.5 Lpm through the nozzle jets (at sonic
flow) at a pressure drop of 0.5 atmospheres (15 in Hg)
or more across the sampler (SKC, 2004). From this
literature, a decision was made to only use the
BioSampler® impinger design in both the wind tunnel
and field studies.
The curved inlet neck of a similar impinger design, the
AGI-30, collects particles larger than 8 urn that can be
recovered with a wash rinse (ACGIH, 1995). Non-
isokinetic collection conditions involving the AGI-30
sampler theoretically result in decreased collection
efficiency of particles larger than 1.0 urn (Grinshpun et
al., 1994). A final rinse procedure, which consisted of
five separate 1.0 ml rinses of a phosphate buffered
solution (PBS) after collection was used to wash down
any organisms that may have aggregated and been in
contact with the inlet neck or nozzles during collection.
Field Study
To prevent dry-out of organisms that might be collected
in the inlet neck, as well as replace impinger fluid that
may be lost to evaporation during outdoor collection
activities, periodic rinses of distilled/de-ionized water
were introduced into the sampler inlet neck during field
collection activities to increase the likelihood that stress-
sensitive organisms could be collected. In addition, the
impingers were covered with aluminum foil to reduce the
chance of any collected bacteria being exposed to ultra-
violet light radiation during the collection and sample
handling period, which might have a detrimental effect
on bacteria.
For the field study, a sampling station layout for the 100
m diameter circular study area (Figure 1) was designed
for flexibility in sampler orientation. Multiple sampling
zones containing multiple sampling stations were spread
apart to increase the size of the collection area of the
sampling field, as opposed to clustering the samplers
within a narrow region of the field. The sampling station
layout included three upwind stations (center station
located 16 m upwind from the top edge of the application
area), three stations in the first downwind zone (center
station located 16 m downwind of the bottom of the
application area), and three stations in the second
downwind zone (center station located 50 m from the
first downwind zone center station). The stations in the
upwind zone and first downwind zone were 75 m apart
within each zone. The stations within the second
downwind zone were approximately 90 m apart. This
station layout would allow physical movement of each
station (following an arc pattern) because the samplers
were secured upon pull carts so that they could be re-
positioned with varying wind patterns.
The operational schedule involved periodic operation of
the samplers for the period of time when the spreader
passed through the application area, with an allowance
time for reasonable particulate transport (two minutes) to
41
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r
5C
UWA
^feHK.U' -Mid
,72T
*
/
/
J^^-
^X'
^r /
/
60m
DWA
Upwind
JUWO
Downwind
(DW)
50m
OWB
Key
A Sampling station containing two Biosamplers
-A- Mobile station containing twq Biosamplers
r = v ^ 0-25m (distance varies per ambient conditions)
A. B and C indicate sampling zone identification
WOT TO SCALE
Figure 1. Plan View of Sampling Station Layout
downwind stations, as opposed to continuous operation
of the samplers. During the time the samplers were off,
distilled water was introduced into the inlet neck. This
intermittent operation and rinsing were intended to
reduce evaporative loss of impinger fluid associated with
outdoor sampling activities.
Results and Discussion
Laboratory Wind Tunnel Studies
Initial Trial Set (trials 1-4)
The initial two trials indicated that the initial sampling
procedure using white mineral oil as a collection fluid in
the BioSamplers®, for a long time period (120 minutes),
42
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was not effective for capturing the stress-sensitive
bacteria (£. coli) introduced into the tunnel, as no growth
was detected. Various reasons for not being able to
culture stress sensitive organisms from the impinger
were considered. One reason may be that "clumping" of
the bacterial cells may be too large for the bend in the
impinger, collecting in the inlet bend, possibly by charge
attraction, and remain sensitive to air drying (if collected
in the sampler inlet). Another reason could be that the
cell viability is reduced due to the agitation in the
impinger being too severe. Another reason is the cell
viability may be reduced during subsequent filtration,
prior to plating. A third trial employed a final inlet and jet
wash after collection, and (PBS) instead of oil as the
collection medium in an attempt to recover any bacteria.
However, to limit air drying, the trial was only performed
for 10 minutes, raising the detection limit for this trial,
which did not result in detection. A fourth trial using
Bacillus spores indicated that the impingers could collect
less stress-sensitive organisms over a thirty minute
collection period.
Continuation Trials (trials 5-7)
The continuation trials ultimately indicated that the
impinger operational practice of using PBS, operated for
30 minutes, employing a final inlet/nozzle wash was
satisfactory for collecting and culturing stress-sensitive
organisms, depending upon the analytical method used
for culturing the bacteria.
Threshold Trials (trials 8-11)
The last set of trials (trials 8, 9, 10 and 11) were used to
determine if a concentration threshold (initial culture)
was necessary to detect organisms in this experimental
set-up. These trials indicated that the culturable counts
from the impingers were dependent upon the initial
solution concentration counts, once above a threshold
(greater than 105 CFU/ml) for this particular wind tunnel
design.
Field Study
The impingers were operated during both a control trial
and biosolids application trial following the sampling and
analytical plan. The re-positioning of the sampling
stations due to changing wind patterns was difficult to
implement because it was difficult to communicate and
coordinate sampling station movement among all
sampling personnel. The intermittent operation of the
samplers and associated rinsing steps was able to be
implemented during the biosolids application period,
using pre-sterilized packets of water. Detectable
bacteria concentrations were observed for the impingers
at each of the sampling stations. Complete statistical
review of this data will be performed in the future.
Conclusions
Impingers may offer some advantages for collecting and
analyzing a large variety of bioaerosol components as
compared to other bioaerosol collection methods which
typically collect only a single biological agent.
Operational strategies are available to potentially
increase the likelihood that stress-sensitive bacteria,
such as Gram-negative bacteria, can be collected and
cultured from air samples. A collection procedure
involving periodic operation and rinsing of the foil
covered impingers, followed by a final rinse step,
resulted in the collection of viable bacteria during a field
application study.
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This paper has been reviewed in accordance with the United
States Environmental Protection Agency's peer and
administrative review policies and approved for presentation
and publication.
Mention of trade name or commercial products does not
constitute endorsement or recommendation by EPA for use.
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